Charge state mapping of mixed valent iron and manganese mineral particles using Scanning Transmission X-ray Microscopy (STXM)

International Nuclear Information System (INIS)

Pecher, K.; Nealson, K.; Kneedler, E.; Rothe, J.; Meigs, G.; Warwick, T.; Tonner, B.

2000-01-01

The interfaces between solid mineral particles and water play a crucial role in partitioning and chemical transformation of many inorganic as well as organic pollutants in environmental systems. Among environmentally significant minerals, mixed-valent oxides and hydroxides of iron (e.g. magnetite, green rusts) and manganese (hausmanite, birnessite) have been recognized as particularly strong sorbents for metal ions. In addition, minerals containing Fe(II) have recently been proven to be powerful reductants for a wide range of pollutants. Chemical properties of these minerals strongly depend on the distribution and availability of reactive sites and little is known quantitatively about the nature of these sites. We have investigated the bulk distribution of charge states of manganese (Mn (II, III, IV)) and iron (Fe(II, III)) in single particles of natural manganese nodules and synthetic green rusts using Scanning Transmission X-ray SpectroMicroscopy (STXM). Pixel resolved spectra (XANES) extracted from stacks of images taken at different wave lengths across the metal absorption edge were fitted to total electron yield (TEY) spectra of single valent reference compounds. Two dimensional maps of bulk charge state distributions clearly reveal domains of different oxidation states within single particles of Mn-nodules and green rust precipitates. Changes of oxidation states of iron were followed as a result of reductive transformation of an environmental contaminant (CCl 4 ) using green rust as the only reductant

Reduction and Immobilization of Radionuclides and Toxic Metal Ions Using Combined Zero Valent Iron and Anaerobic Bacteria; FINAL

International Nuclear Information System (INIS)

Lenly J. Weathers; Lynn E. Katz

2002-01-01

The use of zero valent iron, permeable reactive barriers (PRBs) for groundwater remediation continues to increase. AN exciting variation of this technology involves introducing anaerobic bacteria into these barriers so that both biological and abiotic pollutant removal processes are functional. This work evaluated the hypothesis that a system combining a mixed culture of sulfate reducing bacteria (SRB) with zero valent iron would have a greater cr(VI) removal efficiency and a greater total Cr(VI) removal capacity than a zero valent iron system without the microorganisms. Hence, the overall goal of this research was to compare the performance of these types of systems with regard to their Cr(VI) removal efficiency and total Cr(VI) removal capacity. Both batch and continuous flow reactor systems were evaluated

Reactivity of monoolefin ligand in transition metal complexes

International Nuclear Information System (INIS)

Rybinskaya, M.I.

1978-01-01

The main tendencies in the coordinated olefin ligand property changes are discussed in the transition metal complexes in comparison with free olefins. The review includes the papers published from 1951 up to 1976. It has been shown that in complexes with transition metal cations olefin π-base acquires the ability to react with nucleophylic reagents. Olefin π-acids in complexes with zero valent metals are easily subjected to electrophylic reagent action. At coordination with transition metal cations the olefin properties are generally preserved, while in the zero-valent metal complexes the nonsaturated ligand acquires the properties of a saturated compounds. The ability of transition metal cations in complexes to intensify reactions of nucleophylic bimolecular substitution of vinyl halogen is clearly detected in contrast to the zero valent metal complexes. It has been shown that investigations of the coordinated olefin ligand reactivity give large possibilities in the further development of the organic synthesis. Some reactions are taken as the basis of important industrial processes

Zero-Valent Iron Permeable Reactive Barriers: A Review of Performance

International Nuclear Information System (INIS)

Korte, NE

2001-01-01

This report briefly reviews issues regarding the implementation of the zero-valent iron permeable reactive barrier (PRB) technology at sites managed by the U.S. Department of Energy (DOE). Initially, the PRB technology, using zero-valent iron for the reactive media, was received with great enthusiasm, and DOE invested millions of dollars testing and implementing PRBs. Recently, a negative perception of the technology has been building. This perception is based on the failure of some deployments to satisfy goals for treatment and operating expenses. The purpose of this report, therefore, is to suggest reasons for the problems that have been encountered and to recommend whether DOE should invest in additional research and deployments. The principal conclusion of this review is that the most significant problems have been the result of insufficient characterization, which resulted in poor engineering implementation. Although there are legitimate concerns regarding the longevity of the reactive media, the ability of zero-valent iron to reduce certain chlorinated hydrocarbons and to immobilize certain metals and radionuclides is well documented. The primary problem encountered at some DOE full-scale deployments has been an inadequate assessment of site hydrology, which resulted in misapplication of the technology. The result is PRBs with higher than expected flow velocities and/or incomplete plume capture

Quantum-chemical consideration of extermal valent forms of actinides

International Nuclear Information System (INIS)

Ionova, G.V.; Pershina, V.G.; Spitsyn, V.I.

1982-01-01

Stability of valent forms of actinides that has not yet studied experimentally, is considered within the framework of quantum-chemical considerations. Oxidizing potentials E 0 for actinide elements are determined theoretically. A dependence of the definite valent state stability on relativistic effect is shown. A conclusion is made that oxidizing potential E 0 (4-5) for americium should be higher than E 0 (4-5) for plutonium. A relatively small oxidizing potential E 0 (4-5) for curium speaks about principle possibility of production of five-valent curium in solution, though it is less stable than the six-valent one. Oxidizing potential corresponding to transition of three-valent californium into the four-valent state should be less than the value adopted in literature. A relatively small oxidizing potential of californium E 0 (4-5) speaks about possible existence of five-valent californium in solution

Cryptic Role of Zero-Valent Sulfur in Metal and Metalloid Geochemistry in Euxinic Waters

Science.gov (United States)

Helz, G. R.

2014-12-01

Natural waters that are isolated from the atmosphere in confined aquifers, euxinic basins and sediment pore waters often become sulfidic. These waters are conventionally described simply as reducing environments. But because nature does not constrain their exposure to reducing equivalents (e.g. from organic matter) and oxidizing equivalents (e.g. from Fe,Mn oxides), these reducing environments in fact vary cryptically in their redox characteristics. The implications for trace metal and metalloid cycles are only beginning to be explored. The activity of zero-valent sulfur (aS0), a virtual thermodynamic property, is a potentially useful index for describing this variation. At a particular temperature and ionic strength, aS0 can be quantified from knowledge of pH and the total S(0) to total S(-II) ratio. Although data are incomplete, the deep waters of the Black Sea (aS0 ca. 0.3) appear to be more reducing than the deep waters of the Cariaco Basin (aS0 ca. 0.5) even though both are perennially sulfidic. An apparent manifestation is a greater preponderance of greigite relative to mackinawite in the Cariaco Basin. Interestingly, greigite is stable relative to mackinawite in both basins but predominates only at the higher aS0. Values of aS0 in sulfidic natural waters span the range over which Hg-polysulfide complexes gain predominance over Hg sulfide complexes. Competition between these ligands is thought to influence biological methylation, mercury's route into aquatic and human food chains. In sulfidic deep ground waters, the redox state and consequent mobility of As, a global human hazard, will depend on aS0. At intermediate sulfide concentrations, higher aS0 favors more highly charged and thus less mobile As(V) species relative to As(III) species despite the overall reducing characteristics of such waters. Helz, G.R. (2014) Activity of zero-valent sulfur in sulfidic natural waters. Geochem. Trans. In press.

Design and reactivity of mono- and polymetallic complexes of low valent f-elements

International Nuclear Information System (INIS)

Camp, Clement

2013-01-01

Beyond its importance in nuclear industry the redox chemistry uranium is attracting increasing interest because complexes of low-valent uranium can promote unusual reductive chemistry through unusual reaction pathways, including attractive examples of CO, CO 2 , N 2 , arenes and azides activation in mild condition. Due to the unique coordination and bonding properties of uranium, its compounds could provide an attractive alternative to transition metals for the catalytic transformation of small molecules. However, metal-based multi-electron processes remain uncommon in uranium chemistry especially in comparison with the d-block metals, the chemistry of low-valent uranium being dominated by single-electron transfers. In this context, the first aim of this project was to investigate the association of low-valent uranium to a non-innocent ligand acting as an independent electron reservoir at a same molecule. Accordingly, we interrogated the use of highly p-delocalized Schiff bases ligands for supporting low-valent uranium chemistry. This led to the isolation of electron-rich complexes which are stabilized by storing electrons on the ligands through the formation of C-C bonds. Interestingly, these C-C bonds can be cleaved by oxidizing agents and the electrons released to participate in multi-electron redox reactions. This process was observed within different Schiff-base ligand scaffolds, allowing a tuning of the properties of the compounds. The second part of this work was dedicated to the synthesis of novel trivalent uranium complexes supported by siloxy ligands and the study of their redox reactivity and coordination properties. Novel dinuclear highly-reactive low-valent uranium assemblies were developed. The study of their limited stability revealed that these compounds are spontaneously decomposing through the cleavage of tBu groups from the supporting ligands resulting in the formation of U(IV) species. In parallel, a mononuclear trivalent uranium complex was

Treatment of acid rock drainage using a sulfate-reducing bioreactor with zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, James A., E-mail: jimfield@email.arizona.edu

2016-05-05

Highlights: • Electron donor from zero-valent iron (ZVI) drives sulfate reduction to sulfide. • Sulfide converts soluble heavy metals into sulfide minerals. • Excess sulfide is sequestered by iron preventing discharge. • Corrosion of ZVI consumes acidity in acid rock drainage. • ZVI as reactive material outlasted limestone in removing heavy metals. - Abstract: This study assessed the bioremediation of acid rock drainage (ARD) in flow-through columns testing zero-valent iron (ZVI) for the first time as the sole exogenous electron donor to drive sulfate-reducing bacteria in permeable reactive barriers. Columns containing ZVI, limestone or a mixture of both materials were inoculated with an anaerobic mixed culture and fed a synthetic ARD containing sulfuric acid and heavy metals (initially copper, and later also cadmium and lead). ZVI significantly enhanced sulfate reduction and the heavy metals were extensively removed (>99.7%). Solid-phase analyses showed that heavy metals were precipitated with biogenic sulfide in the columns packed with ZVI. Excess sulfide was sequestered by iron, preventing the discharge of dissolved sulfide. In the absence of ZVI, heavy metals were also significantly removed (>99.8%) due to precipitation with hydroxide and carbonate ions released from the limestone. Vertical-profiles of heavy metals in the columns packing, at the end of the experiment, demonstrated that the ZVI columns still had excess capacity to remove heavy metals, while the capacity of the limestone control column was approaching saturation. The ZVI provided conditions that enhanced sulfate reduction and generated alkalinity. Collectively, the results demonstrate an innovative passive ARD remediation process using ZVI as sole electron-donor.

Treatment of acid rock drainage using a sulfate-reducing bioreactor with zero-valent iron

International Nuclear Information System (INIS)

Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, James A.

2016-01-01

Highlights: • Electron donor from zero-valent iron (ZVI) drives sulfate reduction to sulfide. • Sulfide converts soluble heavy metals into sulfide minerals. • Excess sulfide is sequestered by iron preventing discharge. • Corrosion of ZVI consumes acidity in acid rock drainage. • ZVI as reactive material outlasted limestone in removing heavy metals. - Abstract: This study assessed the bioremediation of acid rock drainage (ARD) in flow-through columns testing zero-valent iron (ZVI) for the first time as the sole exogenous electron donor to drive sulfate-reducing bacteria in permeable reactive barriers. Columns containing ZVI, limestone or a mixture of both materials were inoculated with an anaerobic mixed culture and fed a synthetic ARD containing sulfuric acid and heavy metals (initially copper, and later also cadmium and lead). ZVI significantly enhanced sulfate reduction and the heavy metals were extensively removed (>99.7%). Solid-phase analyses showed that heavy metals were precipitated with biogenic sulfide in the columns packed with ZVI. Excess sulfide was sequestered by iron, preventing the discharge of dissolved sulfide. In the absence of ZVI, heavy metals were also significantly removed (>99.8%) due to precipitation with hydroxide and carbonate ions released from the limestone. Vertical-profiles of heavy metals in the columns packing, at the end of the experiment, demonstrated that the ZVI columns still had excess capacity to remove heavy metals, while the capacity of the limestone control column was approaching saturation. The ZVI provided conditions that enhanced sulfate reduction and generated alkalinity. Collectively, the results demonstrate an innovative passive ARD remediation process using ZVI as sole electron-donor.

Brillouin spectroscopy with surface acoustic waves on intermediate valent, doped SmS

International Nuclear Information System (INIS)

Schaerer, U.; Jung, A.; Wachter, P.

1998-01-01

Brillouin scattering on surface acoustic waves is a very powerful tool to determine the elastic constants of intermediate valent crystals, since the method is non-destructive and no mechanical contact is needed. A strong evidence for intermediate valence is a negative value of Poisson's ratio, which describes the behavior of the volume under uniaxial pressure. SmS by itself makes a semiconductor-metal transition at a pressure of more than 6.5 kbar. When substituting the divalent Sm by a trivalent cation, like Y, La or Tm, SmS can become - depending on the doping concentration - intermediate valent without any applied, external pressure. In this work, we will present measurements of the velocities of the surface acoustic waves and the calculation of the elastic constants of La- and Tm-doped SmS compounds. We found a clear dependence of Poisson's ratio on the doping concentration and on the valence of the materials. Furthermore, we will discuss the mechanism leading to intermediate valence when substituting Sm. Besides the internal, chemical pressure, which is produced by the built in trivalent cations with their smaller ionic radii, we have clear evidence, that the free electrons in the 5d band, induced by the substituting atoms, also play an important role in making doped SmS intermediate valent. (orig.)

Zero-valent iron nanoparticles preparation

International Nuclear Information System (INIS)

Oropeza, S.; Corea, M.; Gómez-Yáñez, C.; Cruz-Rivera, J.J.; Navarro-Clemente, M.E.

2012-01-01

Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH 3 ) 3 ) 2 ] 2 ] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ► Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH 3 ) 3 ) 2 ] 2 ]. ► The conditions of reaction were at room temperature and a pressure of 3 atm. ► The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH 3 ) 3 ) 2 ] 2 ] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

X-ray spectroscopic characterization of Co(IV) and metal–metal interactions in Co₄O₄: Electronic structure contributions to the formation of high-valent states relevant to the oxygen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Hadt, Ryan G.; Hayes, Dugan; Brodsky, Casey N.; Ullman, Andrew M.; Casa, Diego M.; Upton, Mary H.; Nocera, Daniel G; Chen, Lin X.

2016-08-12

In this paper, the formation of high-valent states is a key factor in making highly active transition metal-based catalysts of the oxygen-evolving reaction (OER). These high oxidation states will be strongly influenced by the local geometric and electronic structures of the metal ion, which is difficult to study due to spectroscopically active and complex backgrounds, short lifetimes, and limited concentrations. Here, we use a wide range of complementary X-ray spectroscopies coupled to DFT calculations to study Co₄O₄ cubanes, which provide insight into the high-valent Co(IV) centers responsible for the activity of molecular and heterogeneous OER catalysts. The combination of X-ray absorption and 1s3p resonant inelastic X-ray scattering (Kβ RIXS) allow Co(IV) to be isolated and studied against a spectroscopically active Co(III) background. Co K- and L-edge X-ray absorption data allow for a detailed characterization of the 3d-manifold of effectively localized Co(IV) centers and provide a direct handle on the ligand field environment and covalency of the t_2g-based redox active molecular orbital. Kβ RIXS is also shown to provide a powerful probe of Co(IV), and specific spectral features are sensitive to the degree of oxo-mediated metal-metal coupling across Co₄O₄. Guided by the data, calculations show electron-hole delocalization can actually oppose Co(IV) formation. Computational extension of Co₄O₄ to CoM₃O₄ structures (M = redox-inactive metal) defines electronic structure contri-butions to Co(IV) formation. Redox activity is shown to be linearly related to covalency, and M(III) oxo inductive effects on Co(IV) oxo bonding can tune the covalency of high-valent sites over a large range and thereby tune E⁰ over hundreds of mVs.

Design and reactivity of mono- and polymetallic complexes of low valent f-elements

OpenAIRE

Camp , Clément

2013-01-01

Beyond its importance in nuclear industry the redox chemistry uranium is attracting increasinginterest because complexes of low-valent uranium can promote unusual reductive chemistrythrough unusual reaction pathways, including attractive examples of CO, CO2, N2, arenes andazides activation in mild condition. Due to the unique coordination and bonding properties ofuranium, its compounds could provide an attractive alternative to transition metals for thecatalytic transformation of small molecu...

Amine promoted, metal enhanced degradation of Mirex under high temperature conditions

Energy Technology Data Exchange (ETDEWEB)

Jallad, Karim N. [American University of Sharjah, Department of Chemistry, P.O. Box 26666, Sharjah (United Arab Emirates)]. E-mail: kjallad@runbox.com; Lynn, Bert C. [University of Kentucky, Department of Chemistry, Lexington, KY 40506-055 (United States); Alley, Earl G. [Mississippi State University, Department of Chemistry, MS State, MS 39762 (United States)

2006-07-31

In this study, zero-valent metal dehalogenation of mirex was conducted with amine solvents at high temperatures. Mirex was treated with excess amine in sealed glass tube reactors under nitrogen. The amines used were n-butyl amine (l), ethyl amine (l), dimethyl amine (g), diethyl amine (l), triethyl amine (l), trimethyl amine (g) and ammonia (g). The metals used were copper, zinc, magnesium, aluminum and calcium. The most suitable amine solvent and metal were selected by running a series of reactions with different amines and different zero-valent metals, in order to optimize the conditions under which complete degradation of mirex takes place. These dehalogenation reactions illustrated the role of zero-valent metals as reductants, whereas the amine solvents acted as proton donors. In this study, we report that mirex was completely degraded with diethyl amine (l) in the presence of copper at 100 deg. C and the hydrogenated products accounted for more than 94 of the degraded mirex.

Nanoscale zero-valent iron impregnation of covalent organic polymer grafted activated carbon for water treatment

DEFF Research Database (Denmark)

Mines, Paul D.; Uthuppu, Basil; Thirion, Damien

2016-01-01

The use of nanoscale zero valent iron (nZVI) has quickly become a leading research material for the treatment of typically hard to degrade contaminants found in groundwater. These contaminants include antibiotics, pesticides, halogenated organics, heavy metals, among others. However, the effectiv......The use of nanoscale zero valent iron (nZVI) has quickly become a leading research material for the treatment of typically hard to degrade contaminants found in groundwater. These contaminants include antibiotics, pesticides, halogenated organics, heavy metals, among others. However...... polymeric network already previously proven to stabilize nZVI and a long-standing water treatment material,1 activated carbon; we have developed an advanced material that allows for the not only the stabilization of nZVI, but also the improved degradation of various water contaminants. This was done...... by performing a series of surface modification techniques to the surface of the activated carbon, then physically grafting the covalent organic polymer to the carbon in a shell-like manner, and ultimately synthesizing nZVI in situ within the pores of both the activated carbon and the polymeric network. Not only...

Zero-valent iron nanoparticles preparation

Energy Technology Data Exchange (ETDEWEB)

Oropeza, S. [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Corea, M., E-mail: mcoreat@yahoo.com.mx [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Gómez-Yáñez, C. [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Cruz-Rivera, J.J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra Leona 550, San Luis Potosí, C.P. 78210 (Mexico); Navarro-Clemente, M.E., E-mail: mnavarroc@ipn.mx [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico)

2012-06-15

Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ► Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}]. ► The conditions of reaction were at room temperature and a pressure of 3 atm. ► The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

Sustainable Zero-Valent Metal (ZVM Water Treatment Associated with Diffusion, Infiltration, Abstraction, and Recirculation

Directory of Open Access Journals (Sweden)

David D.J. Antia

2010-09-01

Full Text Available Socio-economic, climate and agricultural stress on water resources have resulted in increased global demand for water while at the same time the proportion of potential water resources which are adversely affected by sodification/salinisation, metals, nitrates, and organic chemicals has increased. Nano-zero-valent metal (n-ZVM injection or placement in aquifers offers a potential partial solution. However, n-ZVM application results in a substantial reduction in aquifer permeability, which in turn can reduce the amount of water that can be abstracted from the aquifer. This study using static diffusion and continuous flow reactors containing n-ZVM and m-ZVM (ZVM filaments, filings and punchings has established that the use of m-ZVM does not result in a reduction in aquifer permeability. The experimental results are used to design and model m-ZVM treatment programs for an aquifer (using recirculation or static diffusion. They also provide a predictive model for water quality associated with specific abstraction rates and infiltration/injection into an aquifer. The study demonstrates that m-ZVM treatment requires 1% of the weight required for n-ZVM treatment for a specific flow rate. It is observed that 1 t Fe0 will process 23,500 m3 of abstracted or infiltrating water. m-ZVM is able to remove >80% of nitrates from flowing water and adjust the water composition (by reduction in an aquifer to optimize removal of nitrates, metals and organic compounds. The experiments demonstrate that ZVM treatment of an aquifer can be used to reduce groundwater salinity by 20 –> 45% and that an aquifer remediation program can be designed to desalinate an aquifer. Modeling indicates that widespread application of m-ZVM water treatment may reduce global socio-economic, climate and agricultural stress on water resources. The rate of oxygen formation during water reduction [by ZVM (Fe0, Al0 and Cu0] controls aquifer permeability, the associated aquifer pH, aquifer Eh

Photoemission studies of mixed valent systems

International Nuclear Information System (INIS)

Parks, R.D.; Raaen, S.; denBoer, M.L.; Williams, G.P.

1984-01-01

Photoemission spectroscopy has been used to study a number of aspects of the mixed valent state (corresponding to non-integral 4f occupation) in rare earth systems. Deep core photoemission (e.g., from 3d or 4d levels) allows the measurement of the 4f occupancy and surface valence shifts, and, as well, the indirect measurement of the effect of solid state environment on the energy of hybridization between 4f electrons and conduction electrons. 4f-Derived photoemission has been used to study surface valance and chemical shifts and to infer the nature of the mixed valent ground state. A combination of 4f-derived photoemission and add-electron spectroscopy provides a measurement of the rf Coulomb correlation energy, an important parameter in the mixed valent problem. A review of these approaches will be presented, with emphasis on Ce-based systems, whose behavior falls outside the usual description of 4f-unstable systems

Nanoscale zero-valent iron for metal/metalloid removal from model hydraulic fracturing wastewater.

Science.gov (United States)

Sun, Yuqing; Lei, Cheng; Khan, Eakalak; Chen, Season S; Tsang, Daniel C W; Ok, Yong Sik; Lin, Daohui; Feng, Yujie; Li, Xiang-Dong

2017-06-01

Nanoscale zero-valent iron (nZVI) was tested for the removal of Cu(II), Zn(II), Cr(VI), and As(V) in model saline wastewaters from hydraulic fracturing. Increasing ionic strength (I) from 0.35 to 4.10 M (Day-1 to Day-90 wastewaters) increased Cu(II) removal (25.4-80.0%), inhibited Zn(II) removal (58.7-42.9%), slightly increased and then reduced Cr(VI) removal (65.7-44.1%), and almost unaffected As(V) removal (66.7-75.1%) by 8-h reaction with nZVI at 1-2 g L -1 . The removal kinetics conformed to pseudo-second-order model, and increasing I decreased the surface area-normalized rate coefficient (k sa ) of Cu(II) and Cr(VI), probably because agglomeration of nZVI in saline wastewaters restricted diffusion of metal(loid)s to active surface sites. Increasing I induced severe Fe dissolution from 0.37 to 0.77% in DIW to 4.87-13.0% in Day-90 wastewater; and Fe dissolution showed a significant positive correlation with Cu(II) removal. With surface stabilization by alginate and polyvinyl alcohol, the performance of entrapped nZVI in Day-90 wastewater was improved for Zn(II) and Cr(VI), and Fe dissolution was restrained (3.20-7.36%). The X-ray spectroscopic analysis and chemical speciation modelling demonstrated that the difference in removal trends from Day-1 to Day-90 wastewaters was attributed to: (i) distinctive removal mechanisms of Cu(II) and Cr(VI) (adsorption, (co-)precipitation, and reduction), compared to Zn(II) (adsorption) and As(V) (bidentate inner-sphere complexation); and (ii) changes in solution speciation (e.g., from Zn 2+ to ZnCl 3 - and ZnCl 4 2- ; from CrO 4 2- to CaCrO 4 complex). Bare nZVI was susceptible to variations in wastewater chemistry while entrapped nZVI was more stable and environmentally benign, which could be used to remove metals/metalloids before subsequent treatment for reuse/disposal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sulfur-Modified Zero-Valent Iron for Remediation Applications at DOE Sites - 13600

Energy Technology Data Exchange (ETDEWEB)

Fogwell, Thomas W. [Fogwell Consulting, P.O. Box 20221, Piedmont, CA 94620 (United States); Santina, Pete [SMI-PS, Inc., 2073 Prado Vista, Lincoln, CA 95648 (United States)

2013-07-01

Many DOE remediation sites have chemicals of concern that are compounds in higher oxidation states, which make them both more mobile and more toxic. The chemical reduction of these compounds both prevents the migration of these chemicals and in some cases reduces the toxicity. It has also been shown that zero-valent iron is a very effective substance to use in reducing oxygenated compounds in various treatment processes. These have included the treatment of halogenated hydrocarbons in the form volatile organic compounds used as solvents and pesticides. Zero-valent iron has also been used to reduce various oxidized metals such as chromium, arsenic, and mercury in order to immobilize them, decrease their toxicity, and prevent further transport. In addition, it has been used to immobilize or break down other non-metallic species such as selenium compounds and nitrates. Of particular interest at several DOE remediation sites is the fact that zero-valent iron is very effective in immobilizing several radioactive metals which are mobile in their oxidized states. These include both technetium and uranium. The main difficulty in using zero-valent iron has been its tendency to become inactive after relatively short periods of time. While it is advantageous to have the zero-valent iron particles as porous as possible in order to provide maximum surface area for reactions to take place, these pores can become clogged when the iron is oxidized. This is due to the fact that ferric oxide has a greater volume for a given mass than metallic iron. When the surfaces of the iron particles oxidize to ferric oxide, the pores become narrower and will eventually shut. In order to minimize the degradation of the chemical activity of the iron due to this process, a modification of zero-valent iron has been developed which prevents or slows this process, which decreases its effectiveness. It is called sulfur-modified iron, and it has been produced in high purity for applications in

Crystallochemistry of rhenium compounds with metal-metal bonds

International Nuclear Information System (INIS)

Koz'min, P.A.; Surazhskaya, M.D.

1980-01-01

A review is presented including a brief description of atomic structure of 59 coordination rhenium compounds with metal-metal bond. The most important bond lengths and valent angles are presented for each compound. The dependence of rhenium-rhenium bond length on its multiplicity is discussed and possible causes of deviations from this dependence (namely, axial ligand presence, steric repulsion of ligands) are considered. On the basis of qualitative comparison of electronegativity of ligands in dimer compounds with quarternary bond of rhenium-rhenium a supposition is made on the influence of formal charge of atomic group and summary electro-negativity of ligands on the possibility of the metal-metal bond formation

Invasive pneumococcal infection despite 7-valent conjugated vaccine

Directory of Open Access Journals (Sweden)

Sebastien Joye

2013-03-01

Full Text Available Despite good cover with 7-valent vaccination, invasive pneumococcal infections may still be misdiagnosed and may lead to lifethreatening situations or death in young children. New serotypes are emerging and, therefore, clinicians must keep a high level of suspicion in young children regardless of their vaccination status. We report three cases of invasive pneumococcal infection due to new serotypes not covered by the 7-valent conjugated vaccine, two of which led children to death.

Reference-free ground truth metric for metal artifact evaluation in CT images

International Nuclear Information System (INIS)

Kratz, Baerbel; Ens, Svitlana; Mueller, Jan; Buzug, Thorsten M.

2011-01-01

Purpose: In computed tomography (CT), metal objects in the region of interest introduce data inconsistencies during acquisition. Reconstructing these data results in an image with star shaped artifacts induced by the metal inconsistencies. To enhance image quality, the influence of the metal objects can be reduced by different metal artifact reduction (MAR) strategies. For an adequate evaluation of new MAR approaches a ground truth reference data set is needed. In technical evaluations, where phantoms can be measured with and without metal inserts, ground truth data can easily be obtained by a second reference data acquisition. Obviously, this is not possible for clinical data. Here, an alternative evaluation method is presented without the need of an additionally acquired reference data set. Methods: The proposed metric is based on an inherent ground truth for metal artifacts as well as MAR methods comparison, where no reference information in terms of a second acquisition is needed. The method is based on the forward projection of a reconstructed image, which is compared to the actually measured projection data. Results: The new evaluation technique is performed on phantom and on clinical CT data with and without MAR. The metric results are then compared with methods using a reference data set as well as an expert-based classification. It is shown that the new approach is an adequate quantification technique for artifact strength in reconstructed metal or MAR CT images. Conclusions: The presented method works solely on the original projection data itself, which yields some advantages compared to distance measures in image domain using two data sets. Beside this, no parameters have to be manually chosen. The new metric is a useful evaluation alternative when no reference data are available.

High-Density Chemical Intercalation of Zero-Valent Copper into Bi 2 Se 3 Nanoribbons

KAUST Repository

Koski, Kristie J.; Cha, Judy J.; Reed, Bryan W.; Wessells, Colin D.; Kong, Desheng; Cui, Yi

2012-01-01

A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi 2Se 3 nanoribbons. Up to 60 atom % copper (Cu 7.5Bi 2Se 3) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction. © 2012 American Chemical Society.

High-Density Chemical Intercalation of Zero-Valent Copper into Bi 2 Se 3 Nanoribbons

KAUST Repository

Koski, Kristie J.

2012-05-09

A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi 2Se 3 nanoribbons. Up to 60 atom % copper (Cu 7.5Bi 2Se 3) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction. © 2012 American Chemical Society.

Effect of humic acid and transition metal ions on the debromination of decabromodiphenyl by nano zero-valent iron: kinetics and mechanisms

Energy Technology Data Exchange (ETDEWEB)

Tan, Lei; Liang, Bin; Fang, Zhanqiang, E-mail: sunmoon124@163.com; Xie, Yingying [South China Normal University, School of Chemistry and Environment (China); Tsang, Eric Pokeung [Guangdong Technology Research Centre for Ecological Management and Remediation of Water System (China)

2014-12-15

E-waste sites are one of the main sources of the pollutant decabromodiphenyl ether (BDE209); contaminated farmland and water bodies urgently need to be remediated. As a potential in situ remediation technology, nano zero-valent iron (nZVI) technology effectively removes PBDEs. However, the humic acid (HA) and heavy metals in the contaminated sites affect the remediation effects. In this study, we explored the influence of HA and transition metals on the removal of PBDEs by nZVI. The specific surface area and average size of the nZVI particles we prepared were 35 m{sup 2}/g and 50–80 nm, respectively. The results showed that HA inhibited the removal of PBDEs; as the concentration of HA increased, its inhibitory effect intensified and the k{sub obs} decreased. However, the three metal ions (Cu{sup 2+}, Co{sup 2+}, and Ni{sup 2+}) enhanced the removal of PBDEs. The enhancement effect was followed the order Ni{sup 2+} > Cu{sup 2+} > Co{sup 2+}. As the concentration of metal ions increased, the promotion effect improved. The synergistic effect of HA and the metal ions was manifested in the combination of the inhibitory effect and the enhancement effect. The values of the first-order kinetic constants (k{sub obs}) under the combined effect were between the values of the rate constants under the individual components. The inhibitory mechanism was the chemisorption of HA, i.e., the benzene carboxylic and phenolic hydroxyl groups in HA occupied the surfactant reactive sites of nZVI, thus inhibiting the removal of BDE209. The promotion mechanism of Cu{sup 2+}, Co{sup 2+}, and Ni{sup 2+} can be explained by their reduction to zero valence on the nZVI surface; furthermore, Ni{sup 2+} strongly affects the debromination and dehydrogenation of BDE209, leading to a stronger promotability than Cu{sup 2+}or Co{sup 2+}.

Phase stabilisation of hexagonal barium titanate doped with transition metals: A computational study

International Nuclear Information System (INIS)

Dawson, J.A.; Freeman, C.L.; Harding, J.H.; Sinclair, D.C.

2013-01-01

Interatomic potentials recently developed for the modelling of BaTiO 3 have been used to explore the stabilisation of the hexagonal polymorph of BaTiO 3 by doping with transition metals (namely Mn, Co, Fe and Ni) at the Ti-site. Classical simulations have been completed on both the cubic and hexagonal polymorphs to investigate the energetic consequences of transition metal doping on each polymorph. Ti-site charge compensation mechanisms have been used for the multi-valent transition metal ions and cluster binding energies have been considered. Simulations show a significant energetic gain when doping occurs at Ti sites in the face sharing dimers (Ti 2 sites) of the hexagonal polymorph compared with the doping of the cubic polymorph. This energetic difference between the two polymorphs is true for all transition metals tested and all charge states and in the case of tri- and tetra-valent dopants negative solution energies are found for the hexagonal polymorph suggesting actual polymorph stabilisation occurs with the incorporation of these ions as observed experimentally. Oxidation during incorporation of Ni 2+ and Fe 3+ ions has also been considered. - Graphical abstract: The representation of the strongest binding energy clusters for tri-valent dopants—(a) Ti 2 /O 1 cluster and (b) Ti 2 /O 2 cluster. Highlights: ► Classical simulations show a significant energetic gain when doping occurs at Ti sites in the face sharing dimers (Ti2 sites) of the hexagonal polymorph compared with the doping of the cubic polymorph. ► This energetic difference between the two polymorphs is true for all transition metals tested and all charge states. ► In the case of tri- and tetra- valent dopants negative solution energies are found for the hexagonal polymorph suggesting actual polymorph stabilisation occurs with the incorporation of these ions

Direct synthesis of metal complexes starting from zero-valent metals

Energy Technology Data Exchange (ETDEWEB)

Gojon-Zorrilla, Gabriel; Kharisov, Boris I. [Universidad Autonoma de Nuevo Leon, Monterrey, Nuevo Leon (Mexico); Garnovskii, Alexander D. [Institute of Physical and Organic Chemistry (Russian Federation)

1996-06-01

The recent (1980-1994) literature on metal-vapor synthesis of coordination and organometallic compounds is reviewed. An account is given of the high-and low-temperature reactions between free metal atoms and a large variety of substrates, mainly alkenes, alkynes, dienes, arenes, funtionalized arenes, alkyl halides {beta}-diketones and simple inorganic molecules. The main experimental methods are described, as well as the results obtained thereby. It is shown that in many instances these methods present significant advantages over conventional synthetic procedures, offering unique access to some metal complexes. [Spanish] Se reviso la literatura reciente (1980-1994) sobre la sintesis de compuestos de coordinacion y compuestos organometalicos a partir de vapores metalicos. Se examinan las reacciones de los atomos metalicos libres con una gran variedad de substratos, principalmente alquenos, alquinos, dienos, hidrocarburos aromaticos y sus derivados, haluros de alquilo y arilo, {beta}-dicetonas y moleculas inorganicas simples. Se presentan los principales metodos experimentales, asi como los resultados obtenidos; se concluye que la crisintesis presenta en muchos casos ventajas significativas sobre los procedimientos sinteticos tradicionales, constituyendo frecuentemente la unica opcion disponible.

On New p-Valent Meromorphic Function Involving Certain Differential and Integral Operators

Directory of Open Access Journals (Sweden)

Aabed Mohammed

2014-01-01

Full Text Available We define new subclasses of meromorphic p-valent functions by using certain differential operator. Combining the differential operator and certain integral operator, we introduce a general p-valent meromorphic function. Then we prove the sufficient conditions for the function in order to be in the new subclasses.

Nanomaterials application for heavy metals recovery from polluted water: The combination of nano zero-valent iron and carbon nanotubes. Competitive adsorption non-linear modeling.

Science.gov (United States)

Vilardi, Giorgio; Mpouras, Thanasis; Dermatas, Dimitris; Verdone, Nicola; Polydera, Angeliki; Di Palma, Luca

2018-06-01

Carbon Nanotubes (CNTs) and nano Zero-Valent Iron (nZVI) particles, as well as two nanocomposites based on these novel nanomaterials, were employed as nano-adsorbents for the removal of hexavalent chromium, selenium and cobalt, from aqueous solutions. Nanomaterials characterization included the determination of their point of zero charge and particle size distribution. CNTs were further analyzed using scanning electron microscopy, thermogravimetric analysis and Raman spectroscopy to determine their morphology and structural properties. Batch experiments were carried out to investigate the removal efficiency and the possible competitive interactions among metal ions. Adsorption was found to be the main removal mechanism, except for Cr(VI) treatment by nZVI, where reduction was the predominant mechanism. The removal efficiency was estimated in decreasing order as CNTs-nZVI > nZVI > CNTs > CNTs-nZVI* independently upon the tested heavy metal. In the case of competitive adsorption, Cr(VI) exhibited the highest affinity for every adsorbent. The preferable Cr(VI) removal was also observed using binary systems of the tested metals by means of the CNTs-nZVI nanocomposite. Single species adsorption was better described by the non-linear Sips model, whilst competitive adsorption followed the modified Langmuir model. The CNTs-nZVI nanocomposite was tested for its reusability, and showed high adsorption efficiency (the q max values decreased less than 50% with respect to the first use) even after three cycles of use. Copyright © 2018 Elsevier Ltd. All rights reserved.

Polyelectrolyte Properties in Mono and Multi-Valent Ionic Media: Brushes and Complex Coacervates

Science.gov (United States)

Farina, Robert M.

Materials composed of polyelectrolytes have unique and interesting physical properties resulting primarily from their charged monomer segments. Polyelectrolytes, which exist in many different biological and industrial forms, have also been shown to be highly responsive to external environmental changes. Here, two specific polyelectrolyte systems, brushes and complex coacervates, are discussed in regards to how their properties can be tailored by adjusting the surrounding ionic environment with mono and multi-valent ions. End-tethered polyelectrolyte brushes, which constitute an interesting and substantial portion of polyelectrolyte applications, are well known for their ability to provide excellent lubrication and low friction when coated onto surfaces (e.g. articular cartilage and medical devices), as well as for their ability to stabilize colloidal particles in solution (e.g. paint and cosmetic materials). These properties have been extensively studied with brushes in pure mono-valent ionic media. However, polyelectrolyte brush interactions with multi-valent ions in solution are much less understood, although highly relevant considering mono and multi-valent counterions are present in most applications. Even at very low concentrations of multi-valent ions in solution, dramatic polyelectrolyte brush physical property changes can occur, resulting in collapsed chains which also adhere to one another via multi-valent bridging. Here, the strong polyelectrolyte poly(sodium styrene sulfonate) was studied using the Surface Forces Apparatus (SFA) and electrochemistry in order to investigate brush height and intermolecular interactions between two brushes as a function of multi-valent counterion population inside a brush. Complex coacervates are formed when polyanions and polycations are mixed together in proper conditions of an aqueous solution. This mixing results in a phase separation of a polymer-rich, coacervate phase composed of a chain network held together via

Synthesis of mixed-valent {alpha}- and {beta}-NaFe{sub 2}O{sub 3} polymorphs under controlled partial oxygen pressure

Energy Technology Data Exchange (ETDEWEB)

Bruno, Shaun R.; Blakely, Colin K. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Poltavets, Viktor V., E-mail: poltavets@chemistry.msu.edu [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)

2012-08-15

Synthesis of mixed valent compounds, especially when multiple polymorphs exist, requires careful control of the preparation conditions. {alpha}- and {beta}-NaFe{sub 2}O{sub 3} polymorphs were synthesized under controlled partial oxygen pressure (pO{sub 2}). pO{sub 2} regions of stability at 850 Degree-Sign C were determined for both phases for the first time. A modified oxygen buffer method was developed for the facile preparation of mixed valent oxides under controlled pO{sub 2}. {beta}-NaFe{sub 2}O{sub 3} is the only known n=2 member of the AM{sub n}O{sub n+1} (A=alkali metal, M=3d metal) rock-salt related homolog series with layered cation ordering. The possibility of new members of the homolog series with other 3d metals is considered. - Graphical abstract: Schematic section of phase composition vs. partial O{sub 2} pressure diagram at 850 Degree-Sign C for Na/Fe=1/2 and structure models of {alpha}- and {beta}-NaFe{sub 2}O{sub 3}. Highlights: Black-Right-Pointing-Pointer {alpha}- and {beta}-NaFe{sub 2}O{sub 3} polymorphs were synthesized under controlled oxygen pressure. Black-Right-Pointing-Pointer {beta}-NaFe{sub 2}O{sub 3} has rock-salt related structure with layered cation ordering. Black-Right-Pointing-Pointer Existence of the rock-salt related homolog series AM{sub n}O{sub n+1} is discussed.

Updated reference design of a liquid metal cooled tandem mirror fusion breeder

International Nuclear Information System (INIS)

Berwald, D.H.; Whitley, R.H.; Garner, J.K.

1985-09-01

Detailed studies of key techinical issues for liquid metal cooled fusion breeder (fusion-fission hybrid blankets) have been performed during the period 1983-4. Based upon the results of these studies, the 1982 reference liquid metal cooled tandem mirror fusion breeder blanket design was updated and is described. The updated reference blankets provides increased breeding and lower technological risk in comparison with the original reference blanket. In addition to the blanket design revisions, a plant concept, cost, and fuel cycle economics assessment is provided. The fusion breeder continues to promise an economical source of fissile fuel for the indefinite future

Updated reference design of a liquid metal cooled tandem mirror fusion breeder

Energy Technology Data Exchange (ETDEWEB)

Berwald, D.H.; Whitley, R.H.; Garner, J.K.; Gromada, R.J.; McCarville, T.J.; Moir, R.W.; Lee, J.D.; Bandini, B.R.; Fulton, F.J.; Wong, C.P.C.; Maya, I.; Hoot, C.G.; Schultz, K.R.; Miller, L.G.; Beeston, J.M.; Harris, B.L.; Westman, R.A.; Ghoniem, N.M.; Orient, G.; Wolfer, M.; DeVan, J.H.; Torterelli, P.

1985-09-01

Detailed studies of key techinical issues for liquid metal cooled fusion breeder (fusion-fission hybrid blankets) have been performed during the period 1983-4. Based upon the results of these studies, the 1982 reference liquid metal cooled tandem mirror fusion breeder blanket design was updated and is described. The updated reference blankets provides increased breeding and lower technological risk in comparison with the original reference blanket. In addition to the blanket design revisions, a plant concept, cost, and fuel cycle economics assessment is provided. The fusion breeder continues to promise an economical source of fissile fuel for the indefinite future.

Modeling σ-Bond Activations by Nickel(0) Beyond Common Approximations: How Accurately Can We Describe Closed-Shell Oxidative Addition Reactions Mediated by Low-Valent Late 3d Transition Metal?

Science.gov (United States)

Hu, Lianrui; Chen, Kejuan; Chen, Hui

2017-10-10

Accurate modelings of reactions involving 3d transition metals (TMs) are very challenging to both ab initio and DFT approaches. To gain more knowledge in this field, we herein explored typical σ-bond activations of H-H, C-H, C-Cl, and C-C bonds promoted by nickel(0), a low-valent late 3d TM. For the key parameters of activation energy (ΔE ‡ ) and reaction energy (ΔE R ) for these reactions, various issues related to the computational accuracy were systematically investigated. From the scrutiny of convergence issue with one-electron basis set, augmented (A) basis functions are found to be important, and the CCSD(T)/CBS level with complete basis set (CBS) limit extrapolation based on augmented double-ζ and triple-ζ basis pair (ADZ and ATZ), which produces deviations below 1 kcal/mol from the reference, is recommended for larger systems. As an alternative, the explicitly correlated F12 method can accelerate the basis set convergence further, especially after its CBS extrapolations. Thus, the CCSD(T)-F12/CBS(ADZ-ATZ) level with computational cost comparable to the conventional CCSD(T)/CBS(ADZ-ATZ) level, is found to reach the accuracy of the conventional CCSD(T)/A5Z level, which produces deviations below 0.5 kcal/mol from the reference, and is also highly recommendable. Scalar relativistic effects and 3s3p core-valence correlation are non-negligible for achieving chemical accuracy of around 1 kcal/mol. From the scrutiny of convergence issue with the N-electron basis set, in comparison with the reference CCSDTQ result, CCSD(T) is found to be able to calculate ΔE ‡ quite accurately, which is not true for the ΔE R calculations. Using highest-level CCSD(T) results of ΔE ‡ in this work as references, we tested 18 DFT methods and found that PBE0 and CAM-B3LYP are among the three best performing functionals, irrespective of DFT empirical dispersion correction. With empirical dispersion correction included, ωB97XD is also recommendable due to its improved

Metal(loid)s behaviour in soils amended with nano zero-valent iron as a function of pH and time.

Science.gov (United States)

Vítková, Martina; Rákosová, Simona; Michálková, Zuzana; Komárek, Michael

2017-01-15

Nano zero-valent iron (nZVI) is currently investigated as a stabilising amendment for contaminated soils. The effect of pH (4-8) and time (48 and 192 h) on the behaviour of nZVI-treated Pb-Zn and As-contaminated soil samples was assessed. Additionally, soil leachates were subsequently used to study the direct interaction between soil solution components and nZVI particles in terms of mineralogical changes and contaminant retention. A typical U-shaped leaching trend as a function of pH was observed for Cd, Pb and Zn, while As was released predominantly under alkaline conditions. Oxidising conditions prevailed, so pH was the key controlling parameter rather than redox conditions. Generally, longer contact time resulted in increased soluble concentrations of metal(loid)s. However, the stabilisation effect of nZVI was only observed after the direct soil leachate-nZVI interactions, showing enhanced redox and sorption processes for the studied metals. A significant decrease of dissolved As concentrations was observed for both experimental soils, but with different efficiencies depending on neutralisation capacity, organic matter content or solid fractionation of As related to the origin of the soils. Scorodite (FeAsO 4 ·2H 2 O) was predicted as a potential solubility-controlling mineral phase for As. Sorption of metal(loid)s onto secondary Fe- and Al-(oxyhydr)oxides (predicted to precipitate at pH > 5) represents an important scavenger mechanism. Moreover, transmission electron microscopy confirmed the retention of Zn and Pb under near-neutral and alkaline conditions by newly formed Fe oxides or aluminosilicates. This study shows that the efficiency of nZVI application strongly depends not only on soil pH-Eh conditions and contaminant type, but also on the presence of organic matter and other compounds such as Al/Fe/Mn oxyhydroxides and clay minerals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanoscale zero-valent iron particles supported on reduced graphene oxides by using a plasma technique and their application for removal of heavy-metal ions.

Science.gov (United States)

Li, Jie; Chen, Changlun; Zhang, Rui; Wang, Xiangke

2015-06-01

Nanoscale zero-valent iron particles supported on reduced graphene oxides (NZVI/rGOs) from spent graphene oxide (GO)-bound iron ions were developed by using a hydrogen/argon plasma reduction method to improve the reactivity and stability of NZVI. The NZVI/rGOs exhibited excellent water treatment performance with excellent removal capacities of 187.16 and 396.37 mg g(-1) for chromium and lead, respectively. Moreover, the NZVI/rGOs could be regenerated by plasma treatment and maintained high removal ability after four cycles. X-ray photoelectron spectroscopy analysis results implied that the removal mechanisms could be attributed to adsorption/precipitation, reduction, or both. Such multiple removal mechanisms by the NZVI/rGOs were attributed to the reduction ability of the NZVI particles and the role of dispersing and stabilizing abilities of the rGOs. The results indicated that the NZVI/rGOs prepared by a hydrogen/argon plasma reduction method might be an effective composite for heavy-metal-ion removal. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effectiveness and ecotoxicity of zero-valent iron nanoparticles during rhizoremediation of soil contaminated with Zn, Cu, Cd and diesel

Directory of Open Access Journals (Sweden)

Rafael G. Lacalle

2018-04-01

Full Text Available The remediation of soils simultaneously contaminated with organic and inorganic compounds is still a challenging task. The application of metallic nanoparticles, such as zero-valent iron nanoparticles (nZVI, for soil remediation is highly promising, but their effectiveness and potential ecotoxicity must be further investigated. In addition, the performance of nZVI when combined with other remediation strategies is a topic of great interest. Here, we present data on soil chemical (pseudo-total and CaCl2-extractable metal concentrations; petroleum hydrocarbon concentrations and biological properties (microbial properties and phytotoxicity after the application of nZVI to soil simultaneously contaminated with Zn, Cu, Cd and diesel, in the absence and presence of other remediation treatments such as the application of an organic amendment and the growth of Brassica napus plants. Soils were artificially contaminated with the abovementioned contaminants. Then, after an aging period of one month, nZVI were applied to the soil and, subsequently, B. napus seeds were sown. Plants were left to grow for one month. Soil samples were collected immediately after artificially contaminating the soil (T1, at sowing (T2 and at harvesting (T3. Overall, the application of nZVI had no effect on contaminant removal, nor on soil microbial parameters. In contrast, it did cause an indirect toxic effect on plant root elongation due to the interaction of nZVI with soil organic matter. These data are useful for researchers and companies interested in the effectiveness and ecotoxicity of zero-valent iron nanoparticles during the remediation of soil contaminated with metals and hydrocarbons, especially when combined with Gentle Remediation Options.

Role of d and f orbitals in the geometries of low-valent actinide compounds. Ab initio studies of U(CH3)3, Np(CH3)3, and Pu(CH3)3

International Nuclear Information System (INIS)

Ortiz, J.V.; Hay, P.J.; Martin, R.L.

1992-01-01

While organoactinide compounds are traditionally characterized by high oxidation states and coordination numbers, the synthesis, chemistry, and electronic properties of low-valent actinide complexes have been receiving greater attention in recent years. Specific examples of complexes in the AnL family are represented by U[N(SiMe 3 ) 2 ] 3 , U[CH(SiMe 3 ) 2 ] 3 , and Np and Pu analogues, for which cases the ligands adopt a pyramidal arrangement around the actinide. In this communication, the authors report the results of one of the first studies of such low-valent complexes to be carried out using ab initio electronic structure techniques. Related molecules include lanthanide species of the form LnX 3 , which also adopt pyramidal geometries and which have been the subject of semi-empirical theoretical investigations. Transition metal MX 3 species, by contrast, can exhibit either planar or pyramidal forms, depending on the nature of the metal and the ligand. 12 refs., 1 fig., 1 tab

Fundamental Studies of The Removal of Contaminants from Ground and Waste Waters Via Reduction By Zero-Valent metals

International Nuclear Information System (INIS)

Yarmoff, Jory A.; Amrhein, Christopher

2002-01-01

Oxyanions of uranium, selenium, chromium, arsenic, technetium, and chlorine (as perchlorate) are frequently found as contaminants on many DOE sites, and in other areas of the U.S.. A potential remediation method is to react the contaminated water with zero-valent iron (ZVI). We are performing fundamental investigations of the interactions of the relevant compounds with Fe filings and single- and poly-crystalline surfaces. The aim of this work is to develop the physical and chemical understanding that is necessary for the development of cleanup techniques and procedures

Bioinspired catalytic generation of high-valent cobalt-oxo species by the axially coordinated CoPc on pyridine-functionalized MWCNTs for the elimination of organic contaminants

Science.gov (United States)

Li, Nan; Wang, Ying; Wu, Chenren; Lu, Wangyang; Pei, Kemei; Chen, Wenxing

2018-03-01

Enzymes have always been a source of inspiration for the design and improvement of catalysts. Many examples are occurring in heme/non-heme metalloenzymes with the generation of active high-valent metal-oxo intermediates that are controlled by the surrounding amino acids/protein and axial residue ligands, facilitating the efficient oxidation of substrates in biochemical processes. Here, the high-valent cobalt-oxo species have been formed during the heterolysis of H2O2 activated by the bioinspired catalyst, axially coordinated cobalt phthalocyanine (CoPc) on pyridine-functionalized multi-walled carbon nanotubes (MWCNTs-Py), characterized by ultraviolet-visible and X-ray photoelectron spectroscopy. Formation process of the active cobalt-oxo species has been further confirmed by electrospray ionization mass spectrometry analysis and the results from the density functional theory (B3LYP/6-311G) calculations. Such high-valent cobalt-oxo species exhibit high reactivity and enough persistence for the oxidation of the target substrate, C.I. Acid Red 1. The oxidation products are nearly biodegradable small molecules identified by ultra-performance liquid chromatography/high-definition mass spectrometry. This strategy provides a foundation on developing efficient and persistent catalytic system, in particular oxidation processes based on the complex catalysts with N4 macrocycle structures.

Costs and cost-effectiveness of 9-valent human papillomavirus (HPV) vaccination in two East African countries.

Science.gov (United States)

Kiatpongsan, Sorapop; Kim, Jane J

2014-01-01

Current prophylactic vaccines against human papillomavirus (HPV) target two of the most oncogenic types, HPV-16 and -18, which contribute to roughly 70% of cervical cancers worldwide. Second-generation HPV vaccines include a 9-valent vaccine, which targets five additional oncogenic HPV types (i.e., 31, 33, 45, 52, and 58) that contribute to another 15-30% of cervical cancer cases. The objective of this study was to determine a range of vaccine costs for which the 9-valent vaccine would be cost-effective in comparison to the current vaccines in two less developed countries (i.e., Kenya and Uganda). The analysis was performed using a natural history disease simulation model of HPV and cervical cancer. The mathematical model simulates individual women from an early age and tracks health events and resource use as they transition through clinically-relevant health states over their lifetime. Epidemiological data on HPV prevalence and cancer incidence were used to adapt the model to Kenya and Uganda. Health benefit, or effectiveness, from HPV vaccination was measured in terms of life expectancy, and costs were measured in international dollars (I$). The incremental cost of the 9-valent vaccine included the added cost of the vaccine counterbalanced by costs averted from additional cancer cases prevented. All future costs and health benefits were discounted at an annual rate of 3% in the base case analysis. We conducted sensitivity analyses to investigate how infection with multiple HPV types, unidentifiable HPV types in cancer cases, and cross-protection against non-vaccine types could affect the potential cost range of the 9-valent vaccine. In the base case analysis in Kenya, we found that vaccination with the 9-valent vaccine was very cost-effective (i.e., had an incremental cost-effectiveness ratio below per-capita GDP), compared to the current vaccines provided the added cost of the 9-valent vaccine did not exceed I$9.7 per vaccinated girl. To be considered very cost

Enhanced decolorization of methyl orange using zero-valent copper nanoparticles under assistance of hydrodynamic cavitation.

Science.gov (United States)

Li, Pan; Song, Yuan; Wang, Shuai; Tao, Zheng; Yu, Shuili; Liu, Yanan

2015-01-01

The rate of reduction reactions of zero-valent metal nanoparticles is restricted by their agglomeration. Hydrodynamic cavitation was used to overcome the disadvantage in this study. Experiments for decolorization of methyl orange azo dye by zero-valent copper nanoparticles were carried out in aqueous solution with and without hydrodynamic cavitation. The results showed that hydrodynamic cavitation greatly accelerated the decolorization rate of methyl orange. The size of nanoparticles was decreased after hydrodynamic cavitation treatment. The effects of important operating parameters such as discharge pressure, initial solution pH, and copper nanoparticle concentration on the degradation rates were studied. It was observed that there was an optimum discharge pressure to get best decolorization performance. Lower solution pH were favorable for the decolorization. The pseudo-first-order kinetic constant for the degradation of methyl orange increased linearly with the copper dose. UV-vis spectroscopic and Fourier transform infrared (FT-IR) analyses confirmed that many degradation intermediates were formed. The results indicated hydroxyl radicals played a key role in the decolorization process. Therefore, the enhancement of decolorization by hydrodynamic cavitation could due to the deagglomeration of nanoparticles as well as the oxidation by the in situ generated hydroxyl radicals. These findings greatly increase the potential of the Cu(0)/hydrodynamic cavitation technique for use in the field of treatment of wastewater containing hazardous materials. Copyright © 2014 Elsevier B.V. All rights reserved.

Cost-effectiveness of 2 + 1 dosing of 13-valent and 10-valent pneumococcal conjugate vaccines in Canada

Directory of Open Access Journals (Sweden)

Earnshaw Stephanie R

2012-04-01

Full Text Available Abstract Background Thirteen-valent pneumococcal conjugate vaccine (PCV13 and 10-valent pneumococcal conjugate vaccine (PCV10 are two recently approved vaccines for the active immunization against Streptococcus pneumoniae causing invasive pneumococcal disease in infants and children. PCV13 offers broader protection against Streptococcus pneumoniae; however, PCV10 offers potential protection against non-typeable Haemophilus influenza (NTHi. We examined public health and economic impacts of a PCV10 and PCV13 pediatric national immunization programs (NIPs in Canada. Methods A decision-analytic model was developed to examine the costs and outcomes associated with PCV10 and PCV13 pediatric NIPs. The model followed individuals over the remainder of their lifetime. Recent disease incidence, serotype coverage, population data, percent vaccinated, costs, and utilities were obtained from the published literature. Direct and indirect effects were derived from 7-valent pneumococcal vaccine. Additional direct effect of 4% was attributed to PCV10 for moderate to severe acute otitis media to account for potential NTHi benefit. Annual number of disease cases and costs (2010 Canadian dollars were presented. Results In Canada, PCV13 was estimated to prevent more cases of disease (49,340 when considering both direct and indirect effects and 7,466 when considering direct effects only than PCV10. This translated to population gains of 258 to 13,828 more quality-adjusted life-years when vaccinating with PCV13 versus PCV10. Annual direct medical costs (including the cost of vaccination were estimated to be reduced by $5.7 million to $132.8 million when vaccinating with PCV13. Thus, PCV13 dominated PCV10, and sensitivity analyses showed PCV13 to always be dominant or cost-effective versus PCV10. Conclusions Considering the epidemiology of pneumococcal disease in Canada, PCV13 is shown to be a cost-saving immunization program because it provides substantial public

Contribution of nuclear analysis methods to the certification of BCR reference materials for non-metals in non-ferrous metals

International Nuclear Information System (INIS)

Pauwels, J.

1979-01-01

A number of reference materials for oxygen in different non-ferrous metals have been certified by BCR in the frame of a multidisciplinary Community project. The contribution of nuclear analysis methods is illustrated by several examples concerning the optimization of sample preparation techniques, the analysis of low and high oxygen non-ferrous metals and the extension of the program to other non-metals, especially nitrogen and carbon. (author)

Zero-valent iron for the removal of soluble uranium in simulated DOE site groundwater

International Nuclear Information System (INIS)

Bostick, W.D.; Jarabek, R.J.; Fiedor, J.N.

1997-01-01

Groundwater at the Bear Creek Valley Characterization Area, located at the Oak Ridge Y-12 Plant, is contaminated with regulated metals and volatile organic compounds (VOCs) due to former site activities and disposal practices. The contaminant of principle concern, from the perspective of protecting human health, is soluble uranium, which is present in some waters at concentrations up to a few parts-per-million. We present product speciation and relative reaction kinetics; for removal of soluble uranium under oxic and anoxic conditions with use of zero-valent iron. Under oxic conditions, U(VI) is rapidly and strongly sorbed to hydrous ferric oxide particulate (open-quotes rustclose quotes), whereas uranium is slowly and incompletely reduced to U(IV) under anoxic conditions

Applications of surface analysis in the environmental sciences: dehalogenation of chlorocarbons with zero-valent iron and iron-containing mineral surfaces

Energy Technology Data Exchange (ETDEWEB)

McGuire, Molly M.; Carlson, Daniel L.; Vikesland, Peter J.; Kohn, Tamar; Grenier, Adam C.; Langley, Laura A.; Roberts, A. Lynn; Fairbrother, D. Howard

2003-10-31

Halogenated organic compounds are common pollutants in groundwater. Consequently, there is widespread interest in understanding the reactions of these compounds in the environment and developing remediation strategies. One area of ongoing research involves the reductive dechlorination of organohalides with zero-valent metals or metal sulfide minerals. These processes have been studied almost exclusively from the perspective of the aqueous phase. In this paper we illustrate the utility of surface analysis techniques, including electron spectroscopies, vibrational spectroscopies, and atomic force microscopy in elucidating the roles played by the surface. A dual analysis approach to the study of reductive dechlorination, combining traditional solution phase analysis with surface analytical techniques, also is demonstrated using a liquid cell coupled to an ultrahigh vacuum surface analysis chamber.

Removal of uranium from uranium plant wastewater using zero-valent iron in an ultrasonic field

Energy Technology Data Exchange (ETDEWEB)

Li, Jing; Zhang, Libo; Peng, Jinhui; Ma, Aiyuan; Xia, Hong Ying; Guo, Wen Qian; Yu, Xia [Yunnan Provincial Key Laboratory of Intensification Metallurgy, Kunming (China); Hu, Jinming; Yang, Lifeng [Nuclear Group Two Seven Two Uranium Industry Limited Liability Company, Hengyang (China)

2016-06-15

Uranium removal from uranium plant wastewater using zero-valent iron in an ultrasonic field was investigated. Batch experiments designed by the response surface methodology (RSM) were conducted to study the effects of pH, ultrasonic reaction time, and dosage of zero-valent iron on uranium removal efficiency. From the experimental data obtained in this work, it was found that the ultrasonic method employing zero-valent iron powder effectively removes uranium from uranium plant wastewater with a uranium concentration of 2,772.23 μg/L. The pH ranges widely from 3 to 7 in the ultrasonic field, and the prediction model obtained by the RSM has good agreement with the experimental results.

Hybrid composites of nano-sized zero valent iron and covalent organic polymers for groundwater contaminant degradation

DEFF Research Database (Denmark)

Mines, Paul D.; Byun, J.; Hwang, Yuhoon

Zero valent iron is commonly used in a variety of treatment technologies (e.g. permeable reactive barriers), though recently a heavier focus has been placed on nano-sized zero valent iron (nZVI). Having superior reductive properties and large surface areas, nZVI is ideal for the degradation of ch...

Mono- and binuclear complexes of low-valent zirconium

NARCIS (Netherlands)

Wielstra, IJtsen

1990-01-01

This thesis is a study on the synthesis and reactivity of low-valent zirconium. The investigation can be divided in two parts: the first describes the chemistry of mono-cyclopentadienyl Zr (II) complexes (Chapter II, III and IV), and the second describes some synthetic pathways successfully used for

DDT, DDD, AND DDE DECHLORINATION BY ZERO-VALENT IRON

Science.gov (United States)

Traditionally, destruction of DDT [1,1,1-trichIoro-2,2-bis(p-chlorophenyl)ethane] for environmental remediation required high-energy processes such as incineration. Here, the capability of powdered zero-valent iron to dechlorinate DDT and related compounds at room tempera...

Effect of accelerated carbonation and zero valent iron on metal leaching from bottom ash.

Science.gov (United States)

Nilsson, M; Andreas, L; Lagerkvist, A

2016-05-01

About 85% of the ashes produced in Sweden originated from the incineration of municipal solid waste and biofuel. The rest comes from the thermal treatment of recycled wood, peat, charcoal and others. About 68% of all ashes annually produced in Sweden are used for constructions on landfills, mainly slopes, roads and embankments, and only 3% for construction of roads and working surfaces outside the landfills (SCB, 2013). Since waste bottom ash (BA) often has similar properties to crushed bedrock or gravel, it could be used for road constructions to a larger extent. However, the leaching of e.g. Cr, Cu, Mo, Pb and Zn can cause a threat to the surrounding environment if the material is used as it is. Carbonation is a commonly used pre-treatment method, yet it is not always sufficient. As leaching from aged ash is often controlled by adsorption to iron oxides, increasing the number of Fe oxide sorption sites can be a way to control the leaching of several critical elements. The importance of iron oxides as sorption sites for metals is known from both mineralogical studies of bottom ash and from the remediation of contaminated soil, where iron is used as an amendment. In this study, zero valent iron (Fe(0)) was added prior to accelerated carbonation in order to increase the number of adsorption sites for metals and thereby reduce leaching. Batch, column and pHstat leaching tests were performed and the leaching behaviour was evaluated with multivariate data analysis. It showed that leaching changed distinctly after the tested treatments, in particular after the combined treatment. Especially, the leaching of Cr and Cu clearly decreased as a result of accelerated carbonation. The combination of accelerated carbonation with Fe(0) addition reduced the leaching of Cr and Cu even further and reduced also the leaching of Mo, Zn, Pb and Cd compared to untreated BA. Compared with only accelerated carbonation, the Fe(0) addition significantly reduced the leaching of Cr, Cu and Mo

Space and Matter in the Poetic and Artistic Perception of José Ángel Valente

Directory of Open Access Journals (Sweden)

Ching Yu Lin

2015-04-01

Full Text Available The poetry of José Ángel Valente brings up fundamental issues of space and matter, combining the poetic voice with the artistic and philosophical thought. It reveals the sense of forms of arc and circle that correspond to the wisdom of Taoism and Zen. Valente composed some poems that responded to the concept of matter represented by Spanish artists, such as Eduardo Chillida, Luis Fernández and Antoni Tàpies. Furthermore, from an ethical perspective, in the poem “Hibakusha”, Valente´s matter offers audio experiences which indicate a space of historical memory and representation of human beings. We are invited to listen to the material and corporal space ruined by atomic bombs.          

The improvement of boron-doped diamond anode system in electrochemical degradation of p-nitrophenol by zero-valent iron

International Nuclear Information System (INIS)

Zhu Xiuping; Ni Jinren

2011-01-01

Boron-doped diamond (BDD) electrodes are promising anode materials in electrochemical treatment of wastewaters containing bio-refractory organic compounds due to their strong oxidation capability and remarkable corrosion stability. In order to further improve the performance of BDD anode system, electrochemical degradation of p-nitrophenol were initially investigated at the BDD anode in the presence of zero-valent iron (ZVI). The results showed that under acidic condition, the performance of BDD anode system containing zero-valent iron (BDD-ZVI system) could be improved with the joint actions of electrochemical oxidation at the BDD anode (39.1%), Fenton's reaction (28.5%), oxidation–reduction at zero-valent iron (17.8%) and coagulation of iron hydroxides (14.6%). Moreover, it was found that under alkaline condition the performance of BDD-ZVI system was significantly enhanced, mainly due to the accelerated release of Fe(II) ions from ZVI and the enhanced oxidation of Fe(II) ions. The dissolved oxygen concentration was significantly reduced by reduction at the cathode, and consequently zero-valent iron corroded to Fe(II) ions in anaerobic highly alkaline environments. Furthermore, the oxidation of released Fe(II) ions to Fe(III) ions and high-valent iron species (e.g., FeO 2+ , FeO 4 2− ) was enhanced by direct electrochemical oxidation at BDD anode.

EXPERIENCE OF USE OF PNEUMOCOCCAL CONJUGATED 7-VALENT VACCINE IN SOME REGIONS OF RUSSIA

Directory of Open Access Journals (Sweden)

A.A. Ruleva

2010-01-01

Full Text Available An experience of immunization with pneumococcal conjugated 7-valent vaccine Prevenar in 234 children under 5 years old with different state of health was analyzed. There were no any severe reactions, postvaccinal complications or local reactions to the vaccine injection. Mild and moderate postvaccinal reactions were detected in 3,4% (n = 8 of children. The vaccine can be used in children under 5 years old.Key words: children, vaccination, pneumococcal conjugated 7-valent vaccine, safety.(Voprosy sovremennoi pediatrii — Current Pediatrics. 2010;9(2:119-123

Synthesis of Zero Valent Iron Nanoparticles (nZVI and its Efficiency in Arsenic Removal from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Ali Reza Rahmani

2011-03-01

Full Text Available The aim of this study to synthesize nanoparticle zero valent iron and to determine its efficiency in arsenic removal from aqueous solutions. Nanoparticles were synthesized by reduction of ferric chloride using sodium borohydrid. The experiments were conducted in a batch system and the effects of pH, contact time, and the concentrations of arsenit, arsenat, and nano zero valent iron were investigated. SEM and XRD were applied for the determination of particle size and characterization of the nanoparticles synthesized. SEM results revealed that synthesized particles were of nano size (1-100 nanometers. At pH=7.0, 99% of arsenit and arsenat was removed when nano zero valent iron concentration was 1 (g L-1  over a retention time of  10 min. Based on the results obtained, the removal efficiency was enhanced with increasing nano zero valent iron dosage and reaction time, but decreased with increasing initial concentration and initial solution pH. The significant removal efficiency, high rate of process and short reaction time showed that iron nano particles are of a significant potential for the removal of arsenic from aqueous solutions.

EXPERIENCE OF APPLICATION AND SAFETY ASSESSMENT OF THE 13-VALENT PNEUMOCOCCAL CONJUGATE VACCINE IN UNDER-5 CHILDREN

Directory of Open Access Journals (Sweden)

M. V. Fedoseenko

2014-01-01

Full Text Available Compulsory use of the 7-valent pneumococcal conjugate vaccine in the framework of national pediatric immunization schedules of the developed countries resulted in significant decrease in the prevalence of the pneumococcal infections induced by the vaccinal serotypes. However, a growth in prevalence of the pneumonia and acute otitis media caused by non-vaccinal strains has also been observed. This required introduction of a new 13-valent pneumococcal conjugate vaccine with a wider range of pneumococcal population coverage. The experience of application accumulated in various countries (2010 onwards and results of the authors’ observations indicate high safety of the 13-valent pneumococcal conjugate vaccine for both healthy under-5 children and patients with various medical issues. The article presents results of the 13-valent pneumococcal conjugate vaccination tolerance assessment. The study involved 110 children from 2 months to 5 years of age. In most cases immunization concurred with other pediatric vaccines. The incidence of local reactions in vaccinated children did not exceed 33%, of generalized reactions – 11%. The authors observed a comparable incidence of side reactions in both virtually healthy children and children with various medical issues.

Certification of a niobium metal reference material for neutron dosimetry (EC nuclear reference material 526)

International Nuclear Information System (INIS)

Ingelbrecht, C.; Pauwels, J.

1990-01-01

Niobium metal, of 99.999% nominal purity, in the form of 0.02 and 0.1 mm thick foil and of 0.5 mm diameter wire, has been certified for its tantalum mass fraction. The certified value of the tantalum mass fraction is 0.3 ± 0.09 mg. Kg -1 , and is based on 70 results obtained by six independent laboratories by neutron activation analysis or inductively coupled plasma mass spectrometry. The material is intended to be used as a reference material in neutron metrology

Methods of preparation and modification of advanced zero-valent iron nanoparticles, their properties and application in water treatment technologies

Science.gov (United States)

Filip, Jan; Kašlík, Josef; Medřík, Ivo; Petala, Eleni; Zbořil, Radek; Slunský, Jan; Černík, Miroslav; Stavělová, Monika

2014-05-01

Zero-valent iron nanoparticles are commonly used in modern water treatment technologies. Compared to conventionally-used macroscopic iron or iron microparticles, the using of nanoparticles has the advantages given mainly by their generally large specific surface area (it drives their high reactivity and/or sorption capacity), small dimensions (it allows their migration e.g. in ground water), and particular physical and chemical properties. Following the applications of zero-valent iron particles in various pilot tests, there arose several critical suggestions for improvements of used nanomaterials and for development of new generation of reactive nanomaterials. In the presentation, the methods of zero-valent iron nanoparticles synthesis will be summarized with a special attention paid to the thermally-induced solid-state reaction allowing preparation of zero-valent iron nanoparticles in an industrial scale. Moreover, the method of thermal reduction of iron-oxide precursors enables to finely tune the critical parameters (mainly particle size and morphology, specific surface area, surface chemistry of nanoparticles etc.) of resulting zero-valet iron nanoparticles. The most important trends of advanced nanoparticles development will be discussed: (i) surface modification of nanomaterilas, (ii) development of nanocomposites and (iii) development of materials for combined reductive-sorption technologies. Laboratory testing of zero-valent iron nanoparticles reactivity and migration will be presented and compared with the field observations: the advanced zero-valent iron nanoparticles were used for groundwater treatment at the locality contaminated by chlorinated hydrocarbons (VC, DCE, TCE and PCE) and reacted nanoparticles were extracted from the sediments for their fate assessment. The authors gratefully acknowledge the support by the Technology Agency of the Czech Republic "Competence Centres" (project No. TE01020218) and the EU FP7 (project NANOREM).

Reversible formation of high-valent-iron-oxo-porphyrin intermediate in heme-based catalysis: revisiting the kinetic model for horseradish peroxidase.

NARCIS (Netherlands)

Haandel, van M.J.H.; Primus, J.L.; Teunis, C.; Boersma, M.G.; Osman, A.M.; Veeger, C.; Rietjens, I.M.C.M.

1998-01-01

Many heme-containing biocatalysts exert their catalytic action through the initial formation of so-called high-valent-iron-oxo porphyrin intermediates. For horseradish peroxidase the initial intermediate formed has been identified as a high-valent-iron-oxo porphyrin π-radical cation, called compound

Remediation of U(VI)-contaminated water using zero-valent iron

International Nuclear Information System (INIS)

Abdelouas, A.; Gong, W.; Lutze, W.; Nuttall, E.

1999-01-01

We investigated the possibility of U(VI) reduction by zero-valent iron (Fe 0 ). We conducted batch experiments with granular iron and solutions containing 0.25 and 9.3 mg L -1 U(VI) at 24 deg C. The solution pH ranges between 2 and 9. In all experiments uranium removal was complete within several hours to several days regardless of the pH value. The reduced uranium precipitated as poorly crystallized hydrated uraninite, UO 2 .nH 2 O. The reduction of U(VI) to U(IV) by Fe 0 was found to be the principal mechanism of U removal from the solution. Other mechanisms such as U(VI) sorption on the newly formed Fe(III) hydroxides are insignificant. These results show that zero-valent iron can be used to remedy U-contaminated waters from uranium mines and mill tailings sites, the pH of which usually ranges between 2 and 9. (authors)

Certification of a nickel metal reference material for neutron dosimetry (EC Nuclear Reference Material 521)

International Nuclear Information System (INIS)

Pauwels, J.

1988-01-01

Nickel metal, of 99.99 % nominal purity and natural isotopic composition, in the form of 0.1 mm thick foil and 0.5 mm diameter wire has been certified for its cobalt mass fraction. The certified value of cobalt (<0.1μg.g-1) is based on 38 results obtained by neutron activation analysis, emission spectrometry with inductively coupled plasma excitation and atomic absorption spectrometry, whereas the isotopic composition of the nickel was verified by thermal ionization mass spectrometry. The material is intended to be used as a reference material in neutron metrology

Certification of an aluminium metal reference material for neutron dosimetry (EC nuclear reference material 523)

International Nuclear Information System (INIS)

Pauwels, J.; Ingelbrecht, C.

1990-01-01

Aluminium metal of > 99.999% nominal purity in the form of 0.1 mm and 1 mm thick foil and of 1 mm diameter wire has been certified for its sodium mass fraction. The certified value of the sodium mass fraction ( -1 ) is based on 21 results from three laboratories using two different methods, which are neutron activation analysis and atomic absorption spectrometry. The overall purity was estimated using spark source mass spectrometry and neutron activation analysis. The material is intended to be used as a reference material in neutron metrology

Certification of a copper metal reference material for neutron dosimetry. (EC nuclear reference material 522)

International Nuclear Information System (INIS)

Ingelbrecht, C.; Pauwels, J.; Lievens, F.

1993-01-01

Copper metal of ≥ 99.995% nominal purity in the form of 0.1 and 1.0 mm thick foil and 0.5 and 1.0 mm diameter wire has been certified for its cobalt and silver mass fractions. The certified values are -1 and 0.95 ± 0.04 mg.kg -1 respectively, based on 66 results for cobalt and 88 results for silver obtained by nine laboratories using three methods. This reference material, EC-NRM 522, is intended for reactor neutron dosimetry. (authors). 14 refs., 1 annexe, 10 tabs., 2 figs

Removal of Technetium, Carbon Tetrachloride, and Metals from DOE Properties - Final Report

International Nuclear Information System (INIS)

Mallouk, Thomas E.; Ponder, S.M.

2000-01-01

This research is a three year project involving close collaboration between chemists at Pennsylvania State University and materials scientists at Pacific Northwest National Laboratory (PNNL). The goal of the project is the development and characterization of supported reducing agents, and solid waste forms derived from them, which will be effective in remediation of aqueous wastes. The work follows the recent discovery that zero-valent metals, such as iron, are effective decontaminants for waste streams containing chlorinated hydrocarbons. Preliminary data, obtained at Penn State and elsewhere, have shown that the same strategy will be effective in reducing soluble compounds containing toxic metals (technetium, lead, mercury, and chromium) to insoluble forms. The Penn State group has prepared a new class of powerful reducing agents, called Ferragels, which consist of finely divided zero-valent metals on high surface area supports. Because the rate of the surface oxidation-reduction reaction depends on available surface area, Ferragels are more effective in every case tested to date than unsupported metals. The project will further develop and investigate the application of these composite materials to problems relevant to the DOE-EM mission, namely the detoxification of waste streams containing technetium, carbon tetrachloride, and toxic metal ions. The Penn State group will work closely with the PNNL group to prepare materials that are compatible with the highly corrosive liquid fraction of Hanford site tank waste, to conduct tests with waste simulants containing technetium, and to formulate and characterize vitrified waste forms derived from these materials

Impacto y efectividad de la vacunación infantil con la vacuna neumocócica conjugada 13-valente en Navarra

OpenAIRE

Guevara Eslava, Marcela

2015-01-01

La vacuna neumocócica conjugada 7 valente (VNC7) comenzó a estar disponibles en España en 2001, la 10-valente (VNC10) en 2009 y la 13-valente (VNC13) en 2010. En Navarra, sin estar incluidas en el calendario oficial de vacunaciones, se ha extendido su uso en los niños. Los objetivos de este estudio han sido evaluar el impacto de la vacunación infantil con la VNC13 sobre la epidemiología de la enfermedad neumocócica invasiva (ENI) en la población de Navarra de todas las edade...

Removal of halogenated organic compounds in landfill gas by top covers containing zero-valent iron

DEFF Research Database (Denmark)

Scheutz, Charlotte; Winther, K.; Kjeldsen, Peter

2000-01-01

Transformation of gaseous CCl3F and CCl4 by zero-valent iron was studied in systems unsaturated with water under anaerobic conditionssin an N2 gas and in a landfill gas atmosphere. The transformation was studied in batch as well as flow-through column tests. In both systems, the transformation....... During continuous aerobic conditions, the transformation of CCl3F decreased toward zero. Model calculations show that use of zero-valent iron in landfill top covers is a potential treatment technology for emission reduction of halogenated trace compounds from landfills....

Synthesis and nature of heterogeneous catalysts of low-valent tungsten supported on alumina

Energy Technology Data Exchange (ETDEWEB)

Brenner, A.; Hucul, D.A.

1980-01-01

Temperature-programed decomposition of catalysts prepared from zero-valent W(CO)/sub 6/ and alumina under rigorously air-free conditions showed a low-temperature carbon monoxide desorption peak at 110/sup 0/-172/sup 0/C, depending on alumina pretreatment, in which a relatively stable surface W(CO)/sub 3/ complex was formed; and a high-temperature carbon monoxide desorption peak at 257/sup 0/ to > 400/sup 0/C, which gave zero-valent tungsten if the ratio of hydroxyl groups of alumina to tungsten surface complexes was low, and hexavalent tungsten if the ratio was high. Up to about half the W(CO)/sub 6/ sublimated from the alumina during activation.

Nitrogen Atom Transfer From High Valent Iron Nitrides

Energy Technology Data Exchange (ETDEWEB)

Johnson, Michael D. [New Mexico State Univ., Las Cruces, NM (United States); Smith, Jeremy M. [Indiana Univ., Bloomington, IN (United States)

2015-10-14

This report describes the synthesis and reactions of high valent iron nitrides. Organonitrogen compounds such as aziridines are useful species for organic synthesis, but there are few efficient methods for their synthesis. Using iron nitrides to catalytically access these species may allow for their synthesis in an energy-and atom-efficient manner. We have developed a new ligand framework to achieve these goals as well as providing a method for inducing previously unknown reactivity.

DEVELOPMENT OF THE REFERENCE MATERIALS PRODUCTION BRANCH IN THE JOINT STOCK COMPANY "THE GULIDOV KRASNOYARSK NON-FERROUS METALS PLANT"

Directory of Open Access Journals (Sweden)

K. A. Shatnykh

2015-01-01

Full Text Available The article deals with the development of the branch for the reference materials production in the Joint Stock Company "The Gulidov Krasnoyarsk Non-Ferrous Metals Plant" (JSC "Krastsvetmet". Here the most important workings for reference materials including the work for the London precious metal exchange, current and future works are stated.

A new large-volume metal reference standard for radioactive waste management.

Science.gov (United States)

Tzika, F; Hult, M; Stroh, H; Marissens, G; Arnold, D; Burda, O; Kovář, P; Suran, J; Listkowska, A; Tyminski, Z

2016-03-01

A new large-volume metal reference standard has been developed. The intended use is for calibration of free-release radioactivity measurement systems and is made up of cast iron tubes placed inside a box of the size of a Euro-pallet (80 × 120 cm). The tubes contain certified activity concentrations of (60)Co (0.290 ± 0.006 Bq g(-1)) and (110m)Ag (3.05 ± 0.09 Bq g(-1)) (reference date: 30 September 2013). They were produced using centrifugal casting from a smelt into which (60)Co was first added and then one piece of neutron irradiated silver wire was progressively diluted. The iron castings were machined to the desirable dimensions. The final material consists of 12 iron tubes of 20 cm outer diameter, 17.6 cm inner diameter, 40 cm length/height and 245.9 kg total mass. This paper describes the reference standard and the process of determining the reference activity values. © The Author 2015. Published by Oxford University Press.

Certification of an iron metal reference material for neutron dosimetry (EC nuclear reference material 524)

International Nuclear Information System (INIS)

Ingelbrecht, C.; Pauwels, J.; Lievens, F.

1993-01-01

Iron metal, of > 99.996% nominal purity, in the form of 0.1 mm thick foil and of 0.5 mm diameter wire has been certified for its manganese and cobalt mass fractions. The certified value of the cobalt mass fraction ( -1 ) is based on 39 accepted results from five laboratories using two different methods. The certified value of the manganese mass fraction ( -1 ) is based on 41 accepted results from five laboratories using three different methods. The overall purity was also verified. The material is intended to be used as a reference material in neutron dosimetry. (authors). 8 refs., 9 tabs., 2 figs

Nucleation and growth of oxides on metals with special reference to mild steel and zirconium

Energy Technology Data Exchange (ETDEWEB)

Gadiyar, H S [Bhabha Atomic Research Centre, Bombay (India). Metallurgy Div.

1977-01-01

The oxidation of metals is a complex phenomenon of metal-gas interface for the understanding of which a multidisciplinary approach is necessary. Some aspects of this phenomena are discussed with reference to oxygen or steam as the oxidant. As a case study, the nucleation of oxide through microstructural characterisation, the kinetics and mechanism involved in the case of oxidation of Zr and its alloys have been examined.

A magnetic route to measure the average oxidation state of mixed-valent manganese in manganese oxide octahedral molecular sieves (OMS).

Science.gov (United States)

Shen, Xiong-Fei; Ding, Yun-Shuang; Liu, Jia; Han, Zhao-Hui; Budnick, Joseph I; Hines, William A; Suib, Steven L

2005-05-04

A magnetic route has been applied for measurement of the average oxidation state (AOS) of mixed-valent manganese in manganese oxide octahedral molecular sieves (OMS). The method gives AOS measurement results in good agreement with titration methods. A maximum analysis deviation error of +/-7% is obtained from 10 sample measurements. The magnetic method is able to (1) confirm the presence of mixed-valent manganese and (2) evaluate AOS and the spin states of d electrons of both single oxidation state and mixed-valent state Mn in manganese oxides. In addition, the magnetic method may be extended to (1) determine AOS of Mn in manganese oxide OMS with dopant "diamagnetic" ions, such as reducible V5+ (3d0) ions, which is inappropriate for the titration method due to interference of redox reactions between these dopant ions and titration reagents, such as KMnO4, (2) evaluate the dopant "paramagnetic" ions that are present as clusters or in the OMS framework, and (3) determine AOS of other mixed-valent/single oxidation state ion systems, such as Mo3+(3d3)-Mo4+(3d2) systems and Fe3+ in FeCl3.

Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhiming [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Zheng, Shuilin [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Ayoko, Godwin A.; Frost, Ray L. [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Xi, Yunfei, E-mail: y.xi@qut.edu.au [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia)

2013-12-15

Graphical abstract: Nanosized zero-valent iron (nZVI) particles were deposited onto acid-leached diatomite through centrifugation or rotary evaporation. The synthesis schematic diagram and morphology of the prepared nZVI/diatomite composites are shown in the illustration. The removal efficiency for herbicide simazine by nZVI/diatomite composites was compared with that of the pristine nZVI and the commercial iron powder. -- Highlights: • Diatomite-supported nanosized zero-valent iron composite was synthesised. • The obtained composites were characterised by XRD, SEM–EDS, TEM and XPS. • The removal efficiency for simazine in water were studied. • The prepared composite showed potential prospects in environmental remediation. -- Abstract: A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent

Antimony Adsorption from Zarshouran Gold Mineral Processing Plant Wastewater by Nano Zero Valent Iron Coated on Bentonite

Directory of Open Access Journals (Sweden)

nader nosrati

2015-03-01

Full Text Available The effluent from Zarshouran gold mineral processing plant contains high quantities of arsenic, antimony, mercury, and bismuth. These metals and metalloids are soluble in water and very toxic when they enter the environment. Their solubility in water causes the polluted area to extend beyond their point of origin. In this article, different methods of antimony removal from water and wastewater were reviewed and the zero-valent iron nanoparticles coated on Bentonite were selected as an effective and low cost material for removing antimony from wastewater. For the purposes of this study, zero-valent iron nanoparticles of 40-100 nanometers in size were synthesized by dropwise addition of sodium borohydride solution to an Iron (III aqueous solution at  ambient temperature and mixed with nitrogen gas. To avoid particle agglomeration and to enhance the product’s environmentally safe application, the  nanoparticles were coated on Bentonite and characterized by SEM/EDAX and BET. The experiments were carried out by intense mixing of the adsorbent with 10ml of real/synthtic wastewater samples in 20ml bottles.  The effects of pH, contact time, temperature, and adsorbent dosage on antimony removal efficiency were investigated under intense mixing using a magnetic mixer. Finally, the effluents were filtered upon completion of the experiments and used for atomic adsorption analysis. The results of the experiments showed that the adsorption isotherms of the synthesized nanoparticles obeyed the Langmuir and Freundlich models. The experiments carried out on real samples showed that antimony adsorption capacity for B-nZVI was 2.6 mg/g of the adsorbent and that the highest antimony removal efficiency was 99.56%.

Mise à jour sur le nouveau vaccin 9-valent pour la prévention du virus du papillome humain

Science.gov (United States)

Yang, David Yi; Bracken, Keyna

2016-01-01

Résumé Objectif Informer les médecins de famille quant à l’efficacité, à l’innocuité, aux effets sur la santé publique et à la rentabilité du vaccin 9-valent contre le virus du papillome humain (VPH). Qualité des données Des articles pertinents publiés dans PubMed jusqu’en mai 2015 ont été examinés et analysés. La plupart des données citées sont de niveau I (essais randomisés et contrôlés et méta-analyses) ou de niveau II (études transversales, cas-témoins et épidémiologiques). Des rapports et recommandations du gouvernement sont aussi cités en référence. Message principal Le vaccin 9-valent contre le VPH, qui offre une protection contre les types 6, 11, 16, 18, 31, 33, 45, 52 et 58 du VPH, est sûr et efficace et réduira encore plus l’incidence des infections à VPH, de même que les cas de cancer lié au VPH. Il peut également protéger indirectement les personnes non immunisées par l’entremise du phénomène d’immunité collective. Un programme d’immunisation efficace peut prévenir la plupart des cancers du col de l’utérus. Les analyses montrent que la rentabilité du vaccin 9-valent chez les femmes est comparable à celle du vaccin quadrivalent original contre le VPH (qui protège contre les types 6, 11, 16 et 18 du VPH) en usage à l’heure actuelle. Toutefois, il faut investiguer plus en profondeur l’utilité d’immuniser les garçons avec le vaccin 9-valent contre le VPH. Conclusion en plus d’être sûr, le vaccin 9-valent protège mieux contre le VPH que le vaccin quadrivalent. Une analyse coûtefficacité en favorise l’emploi, du moins chez les adolescentes. Ainsi, les médecins devraient recommander le vaccin 9-valent à leurs patients plutôt que le vaccin quadrivalent contre le VPH.

Oxidant production from corrosion of nano- and microparticulate zero-valent iron in the presence of oxygen: A comparative study

International Nuclear Information System (INIS)

Lee, Hongshin; Lee, Hye-jin; Kim, Hyung-Eun; Kweon, Jihyang; Lee, Byeong-Dae; Lee, Changha

2014-01-01

Highlights: • Oxidants from zero-valent iron were quantified in the presence of oxygen and EDTA. • The oxidant yields of nano- and microparticulate zero-valent iron were compared. • Microparticulate zero-valent iron produced higher oxidant yields. • The factors affecting the oxidant production from zero-valent iron were discussed. -- Abstract: In aqueous solution, zero-valent iron (ZVI, Fe 0 ) is known to activate oxygen (O 2 ) into reactive oxidants such as hydroxyl radical and ferryl ion capable of oxidizing contaminants. However, little is known about the effect of the particle size of ZVI on the yield of reactive oxidants. In this study, the production of reactive oxidants from nanoparticulate and microparticulate ZVIs (denoted as nZVI and mZVI, respectively) was comparatively investigated in the presence of O 2 and EDTA. To quantify the oxidant yield, excess amount of methanol was employed, and the formation of its oxidation product, formaldehyde (HCHO), was monitored. The concentration of HCHO in the nZVI/O 2 system rapidly reached the saturation value, whereas that in the mZVI/O 2 system gradually increased throughout the entire reaction time. The mZVI/O 2 system exhibited higher yields of HCHO than the nZVI/O 2 system under both acidic and neutral pH conditions. The higher oxidant yields in the mZVI/O 2 system are mainly attributed to the less reactivity of the mZVI surface with hydrogen peroxide (H 2 O 2 ) relative to the surface of nZVI, which minimize the loss of H 2 O 2 by ZVI (i.e., the two-electron reduction of H 2 O 2 into water). In addition, the slow dissolution of Fe(II) from mZVI was found to be partially responsible for the higher oxidant yields at neutral pH

I. Hole-transporting dendrimers and their use in organic light-emitting devices (OLEDs) and II. Novel layered catalysts containing bipyridinium and zero-valent metal species

Science.gov (United States)

Koene, Shannon Carol

A series of polyaromatic ether/ester dendrimers containing a hole transporting naphthylphenylbenzyl amine at the periphery and a variety of fluorescent dyes at the core has been studied in an effort to observe energy transfer in these species. The dyes incorporated in these dendrimers include 1,4-dihydroxyanthraquinone (quinizarin), Coumarin 343, and a benzopentathiophene. These dendrimers have been incorporated into both single layer and heterostructure organic light emitting devices (OLEDs). In the case of first generation dendrimer OLEDs, excimer/exciplex formation was predominant. In third generation dendrimers, complete energy transfer from the periphery to the dye at the core was observed both in photoluminescence spectra and electroluminescence in OLEDs. Dendrimers containing different dye cores can be combined to achieve color mixing/tuning. In addition, layered catalysts were prepared via both covalent and electrostatic means to achieve the catalytic production of hydrogen peroxide from hydrogen and oxygen. Covalent catalysts were prepared by first growing layers of zirconium and a bipyridinium containing bisphosphonate onto silica particles. Palladium and/or platinum was ion-exchanged into the structure and reduced to the zero valent metal by hydrogen gas. A second set of catalysts was prepared by electrostatically depositing polycations/polyanions onto carboxylate or amine functionalized polystyrene microspheres. Anionic colloidal particles were adsorbed to the polycationic surface. An octacationic viologen oligomer was used in an attempt to increase the affinity of adsorption of the Pd particles to the surface of the microspheres. Catalytic studies of both types of catalysts are herein reported.

Thermodynamics and structure of liquid alkali metals from the charged-hard-sphere reference fluid

International Nuclear Information System (INIS)

Lai, S.K.; Akinlade, O.; Tosi, M.P.

1989-12-01

The evaluation of thermodynamic properties of liquid alkali metals is re-examined in the approach based on the Gibbs-Bogoliubov inequality and using the fluid of charged hard spheres in the mean spherical approximation as reference system, with a view to achieving consistency with the liquid structure factor. The perturbative variational calculation of the Helmholtz free energy is based on an ab initio and highly reliable nonlocal pseudopotential. Only limited improvement is found in the calculated thermodynamic functions, even when full advantage is taken of the two variational parameters inherent in this approach. The role of thermodynamic self-consistency between the equations of state of the reference fluid derived from the routes of the internal energy and of the virial theorem is then discussed, using previous results by Hoye and Stell. An approximate evaluation of the corresponding contribution to the free energy of liquid alkali metals yields appreciable improvements in both the thermodynamic functions and the liquid structure factor. It thus appears that an accurate treatment of thermodynamic self-consistency in the charged-hard-sphere system may help to resolve some of the difficulties that are commonly met in the evaluation of thermodynamic and structural properties of liquid metals. (author). 55 refs, 4 figs, 4 tabs

Toxicity of zero-valent iron nanoparticles to a trichloroethylene-degrading groundwater microbial community.

Science.gov (United States)

Zabetakis, Kara M; Niño de Guzmán, Gabriela T; Torrents, Alba; Yarwood, Stephanie

2015-01-01

The microbiological impact of zero-valent iron used in the remediation of groundwater was investigated by exposing a trichloroethylene-degrading anaerobic microbial community to two types of iron nanoparticles. Changes in total bacterial and archaeal population numbers were analyzed using qPCR and were compared to results from a blank and negative control to assess for microbial toxicity. Additionally, the results were compared to those of samples exposed to silver nanoparticles and iron filings in an attempt to discern the source of toxicity. Statistical analysis revealed that the three different iron treatments were equally toxic to the total bacteria and archaea populations, as compared with the controls. Conversely, the silver nanoparticles had a limited statistical impact when compared to the controls and increased the microbial populations in some instances. Therefore, the findings suggest that zero-valent iron toxicity does not result from a unique nanoparticle-based effect.

Estimating the Clinical and Economic Impact of Maintaining use of 13-valent Pneumococcal Conjugate Vaccine (PCV13) in Mexico

OpenAIRE

Wasserman, Matt; Wilson, Michele; McDade, Cheryl; Grajales, Ana Gabriela; Palacios, Maria Gabriela; Baez- Revueltas, Fabiola Berenice; Farkouh, Raymond

2017-01-01

Abstract Background PCV13 replaced 7-valent pneumococcal conjugate vaccine in the routine infant immunization schedule in Mexico since 2011. The use of PCV13 has reduced pneumococcal disease incidence for vaccine serotypes, particularly 19A, which emerged following PCV7 use. The 10-valent vaccine (PCV10) contains the same serotypes as PCV13 with the exception of serotypes 3, 19A and 6A but also has different conjugated proteins for the common serotypes. This study evaluated the potential heal...

Structure factor of liquid alkali metals using a classical-plasma reference system

Science.gov (United States)

Pastore, G.; Tosi, M. P.

1984-06-01

This paper presents calculations of the liquid structure factor of the alkali metals near freezing, starting from the classical plasma of bare ions as reference liquid. The indirect ion-ion interaction arising from electronic screening is treated by an optimized random phase approximation (ORPA), imposing physical requirements as in the original ORPA scheme developed by Weeks, Chandler and Andersen for liquids with strongly repulsive core potentials. A comparison of the results with computer simulation data for a model of liquid rubidium shows that the present approach overcomes the well-known difficulties met in applying to these metals the standard ORPA based on a reference liquid of neutral hard spheres. The optimization scheme is also shown to be equivalent to a reduction of the range of the indirect interaction in momentum space, as proposed empirically in an earlier work. Comparison with experiment for the other alkalis shows that a good overall representation of the data can be obtained for sodium, potassium and cesium, but not for lithium, when one uses a very simple form of the electron-ion potential adjusted to the liquid compressibility. The small-angle scattering region is finally examined more carefully in the light of recent data of Waseda, with a view to possible refinements of the pseudopotential model.

Dehalogenation of aromatic halides by polyaniline/zero-valent iron composite nanofiber: Kinetics and mechanisms

CSIR Research Space (South Africa)

Giri, S

2016-03-01

Full Text Available Dehalogenation of aryl halides was demonstrated using polyaniline/zero valent iron composite nanofiber (termed as PANI/Fe0) as a cheap, efficient and environmentally friendly heterogeneous catalyst. The catalyst was prepared via rapid mixing...

Long-term Performance of Permeable Reactive Barriers Using Zero-valent Iron: An Evaluation at Two Sites

National Research Council Canada - National Science Library

Wilkin, Richard T; Puls, Robert W; Sewell, Guy W

2002-01-01

Research described in this research brief explores the geochemical and microbiological processes occurring within zero-valent iron treatment zones in permeable reactive barriers that may contribute...

Tailoring the properties of a zero-valent iron-based composite by mechanochemistry for nitrophenols degradation in wastewaters.

Science.gov (United States)

Cagnetta, Giovanni; Huang, Jun; Lomovskiy, Igor O; Yu, Gang

2017-11-01

Zero-valent iron (ZVI) is a valuable material for environmental remediation, because of its safeness, large availability, and inexpensiveness. Moreover, its reactivity can be improved by addition of (nano-) particles of other elements such as noble metals. However, common preparation methods for this kind of iron-based composites involve wet precipitation of noble metal salt precursors, so they are often expensive and not green. Mechanochemical procedures can provide a solvent-free alternative, even at a large scale. The present study demonstrates that it is possible to tailor functional properties of ZVI-based materials, utilizing high-energy ball milling. All main preparation parameters are investigated and discussed. Specifically, a copper-carbon-iron ternary composite was prepared for fast degradation of 4-nitrophenol (utilized as model pollutant) to 4-aminophenol and other phenolic compounds. Copper and carbon are purposely chosen to insert specific properties to the composite: Copper acts as efficient nano-cathode that enhances electron transfer from iron to 4-nitrophenol, while carbon protects the iron surface from fast oxidation in open air. In this way, the reactive material can rapidly reduce high concentration of nitrophenols in water, it does not require acid washing to be activated, and can be stored in open air for one week without any significant activity loss.

Microbial community analysis of perchlorate-reducing cultures growing on zero-valent iron

International Nuclear Information System (INIS)

Son, Ahjeong; Schmidt, Carl J.; Shin, Hyejin; Cha, Daniel K.

2011-01-01

Anaerobic microbial mixed cultures demonstrated its ability to completely remove perchlorate in the presence of zero-valent iron. In order to understand the major microbial reaction in the iron-supported culture, community analysis comprising of microbial fatty acids and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) techniques was performed for perchlorate reducing cultures. Analysis of fatty acid methyl esters (FAMEs) and subsequent principal component analysis (PCA) showed clear distinctions not only between iron-supported perchlorate reducing culture and seed bacteria, but also among perchlorate-reducing cultures receiving different electron donors. The DGGE pattern targeting the chlorite dismutase (cld) gene showed that iron-supported perchlorate reducing culture is similar to hydrogen-fed cultures as compared to acetate-fed culture. The phylogenetic tree suggested that the dominant microbial reaction may be a combination of the autotrophic and heterotrophic reduction of perchlorate. Both molecular and chemotaxonomic experimental results support further understanding in the function of zero-valent iron as an adequate electron source for enhancing the microbial perchlorate reduction in natural and engineered systems.

Microbial community analysis of perchlorate-reducing cultures growing on zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Son, Ahjeong, E-mail: ason@auburn.edu [Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Schmidt, Carl J. [Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716 (United States); Shin, Hyejin [Department of Mathematics and Statistics, Auburn University, Auburn, AL 36849 (United States); Cha, Daniel K. [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States)

2011-01-30

Anaerobic microbial mixed cultures demonstrated its ability to completely remove perchlorate in the presence of zero-valent iron. In order to understand the major microbial reaction in the iron-supported culture, community analysis comprising of microbial fatty acids and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) techniques was performed for perchlorate reducing cultures. Analysis of fatty acid methyl esters (FAMEs) and subsequent principal component analysis (PCA) showed clear distinctions not only between iron-supported perchlorate reducing culture and seed bacteria, but also among perchlorate-reducing cultures receiving different electron donors. The DGGE pattern targeting the chlorite dismutase (cld) gene showed that iron-supported perchlorate reducing culture is similar to hydrogen-fed cultures as compared to acetate-fed culture. The phylogenetic tree suggested that the dominant microbial reaction may be a combination of the autotrophic and heterotrophic reduction of perchlorate. Both molecular and chemotaxonomic experimental results support further understanding in the function of zero-valent iron as an adequate electron source for enhancing the microbial perchlorate reduction in natural and engineered systems.

Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

Science.gov (United States)

Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

2015-11-16

Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

GROUND WATER REMEDIATION OF CHROMIUM USING ZERO-VALENT IRON IN A PERMEABLE REACTIVE BARRIER

Science.gov (United States)

A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of ...

Total aerobic destruction of azo contaminants with nanoscale zero-valent copper at neutral pH: promotion effect of in-situ generated carbon center radicals.

Science.gov (United States)

Dong, Guohui; Ai, Zhihui; Zhang, Lizhi

2014-12-01

In this study, nanoscale zero-valent copper (nZVC) was synthesized with a facile solvothermal method and used for the aerobic removal of azo contaminants at neutral pH for the first time. We found that both Cu(I) and OH generated during the nZVC induced molecular oxygen activation process accounted for the rapid total destruction of azo contaminants in the nZVC/Air system, where nZVC could activate molecular oxygen to produce H2O2, and also release Cu(I) to break the -NN- bond of azo contaminants via the sandmeyer reaction for the generation of carbon center radicals. The in-situ generated carbon center radicals would then react with OH produced by the Cu(I) catalyzed decomposition of H2O2, resulting in the generation of low molecular weight organic acids and their subsequent mineralization. The indispensible role of Cu(I) catalyzed sandmeyer reaction and the promotion effect of in-situ generated carbon center radicals on the rapid total destruction of azo contaminants in the nZVC/Air system were confirmed by gas chromatography-mass spectrometry analysis. This study can deepen our understanding on the degradation of organic pollutant with molecular oxygen activated by zero valent metal, and also provide a new method to remove azo contaminants at neutral pH. Copyright © 2014 Elsevier Ltd. All rights reserved.

“El cántaro” o la creatividad de lo vacuo en la poesía de José Ángel Valente

Directory of Open Access Journals (Sweden)

Calvo Rodríguez, José Andrés

2007-08-01

Full Text Available Through the commentary of “the pitcher”, one of the most important poems of Poemas a Lázaro (1960, studies the importance of androginia in Valente’s poetry and poetic. Taking the symbol from pitcher-song, Valente develops a sustained poetic theory in two fundamental concepts: negation and inmanencia. Both concepts lead to a poetry characterized by the fusion of semantic opposites like necessary step in the search of the poetic center. By all this, the impact in the Valente’s poetry of the opposition between essence/existence, realism/nominalism and relevance of the musical canon within the poetry of the orensano is analyzed. In this philosophical context, poetic and mystical, the poetry of Valente with the Taoism and the theory of the relativity of Einstein through a text of Ortega and Gasset is compared.A través del comentario de “El cántaro”, uno de los poemas más importantes del Valente de Poemas a Lázaro (1960, se estudia la importancia de la androginia en la poesía y en la poética valentianas. Tomando el símbolo del cántaro-canto, Valente desarrolla una teoría poética sustentada en dos conceptos fundamentales: negación e inmanencia. Ambos conceptos conducen a una poesía caracterizada por la fusión de contrarios semánticos como paso necesario en la búsqueda del centro poético. Por todo esto, se analiza el impacto en la poesía de Valente de la oposición esencialismo/existencialismo, realismo/nominalismo y la relevancia de los cánones musicales dentro de la poesía del orensano. En este contexto filosófico, poético y místico, se compara la poesía de Valente con el taoísmo y con la teoría de la relatividad de Einstein a través de un ensayo de Ortega y Gasset.

Removal of Cr(VI) by nanoscale zero-valent iron (nZVI) from soil contaminated with tannery wastes.

Science.gov (United States)

Singh, Ritu; Misra, Virendra; Singh, Rana Pratap

2012-02-01

The illegal disposal of tannery wastes at Rania, Kanpur has resulted in accumulation of hexavalent chromium [Cr(VI)], a toxic heavy metal in soil posing risk to human health and environment. 27 soil samples were collected at various depths from Rania for the assessment of Cr(VI) level in soil. Out of 27 samples, five samples had shown significant level of Cr(VI) with an average concentration of 15.84 mg Kg(-1). Varied doses of nanoscale zero-valent iron (nZVI) were applied on Cr(VI) containing soil samples for remediation of Cr(VI). Results showed that 0.10 g L(-1) nZVI completely reduces Cr(VI) within 120 min following pseudo first order kinetics. Further, to test the efficacy of nZVI in field, soil windrow experiments were performed at the contaminated site. nZVI showed significant Cr(VI) reduction at field also, indicating it an effective tool for managing sites contaminated with Cr(VI).

Competitive Adsorption and Oxidation Behavior of Heavy Metals on nZVI Coated with TEOS.

Science.gov (United States)

Eglal, Mahmoud M; Ramamurthy, Amruthur S

2015-11-01

Zero valent iron nanoparticle (nanofer ZVI) is a powerful substance due to its coating with tetraethyl orthosilicate (TEOS). Tetraethyl orthosilicate imparts higher reactivity and decreases particle agglomeration. The competitive removal and displacement of multi-metals are influenced by time, pH, and initial concentration, the presence and properties of competing metals ion in the solution. For both the isotherm and kinetic studies performed for multi-metal removal experiments, compared to Pb II and Cd II, Cu II experienced a higher removal rate during the initial 5 minutes. After 120 minutes, all metals achieved removal efficiency in the range of 95 to 99%. The results of single and competitive kinetic tests for all three metals during the initial 5 minutes indicated that the presence of other metals generally reduce removal efficiency of metals. Both kinetic test and electron dispersive spectroscope (EDS) studies found that Cu II gets removed faster than the other metals. Pseudo-second order behavior was noted for the multi-metal removal systems.

Comparison of 2-Dose and 3-Dose 9-Valent Human Papillomavirus Vaccine Schedules in the United States: A Cost-effectiveness Analysis.

Science.gov (United States)

Laprise, Jean-François; Markowitz, Lauri E; Chesson, Harrell W; Drolet, Mélanie; Brisson, Marc

2016-09-01

A recent clinical trial using the 9-valent human papillomavirus virus (HPV) vaccine has shown that antibody responses after 2 doses are noninferior to those after 3 doses, suggesting that 2 and 3 doses may have comparable vaccine efficacy. We used an individual-based transmission-dynamic model to compare the population-level effectiveness and cost-effectiveness of 2- and 3-dose schedules of 9-valent HPV vaccine in the United States. Our model predicts that if 2 doses of 9-valent vaccine protect for ≥20 years, the additional benefits of a 3-dose schedule are small as compared to those of 2-dose schedules, and 2-dose schedules are likely much more cost-efficient than 3-dose schedules. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

A novel conditioning process for enhancing dewaterability of waste activated sludge by combination of zero-valent iron and persulfate.

Science.gov (United States)

Zhou, Xu; Wang, Qilin; Jiang, Guangming; Liu, Peng; Yuan, Zhiguo

2015-06-01

Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel conditioning method for improving waste activated sludge dewaterability by combination of persulfate and zero-valent iron. The combination of zero-valent iron (0-30g/L) and persulfate (0-6g/L) under neutral pH substantially enhanced the sludge dewaterability due to the advanced oxidization reactions. The highest enhancement of sludge dewaterability was achieved at 4g persulfate/L and 15g zero-valent iron/L, with which the capillary suction time was reduced by over 50%. The release of soluble chemical oxygen demand during the conditioning process implied the decomposition of sludge structure and microorganisms, which facilitated the improvement of dewaterability due to the release of bound water that was included in sludge structure and microorganism. Economic analysis showed that the proposed conditioning process with persulfate and ZVI is more economically favorable for improving WAS dewaterability than classical Fenton reagent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation of bis- p -nitrophenyl phosphate using zero-valent iron nanoparticles

International Nuclear Information System (INIS)

Valle-Orta, Maiby; Guerrero, Rubén Saldivar; Díaz, David; Dubé, Inti Zumeta; Quiñonez, José Luis Ortiz

2017-01-01

Phosphate esters are employed in some agrochemical formulations and have long life time in the Environment. They are neurotoxic to mammals and it is very difficult to hydrolyze them. It is easy to find papers in the literature dealing with transition metal complexes used in the hydrolysis processes of organophosphorous compounds. However, there are few reports related with degradation of phosphate esters with inorganic nanoparticles. In this work bis-4-nitrophenyl phosphate (BNPP) was used as an agrochemical agent model. The BNPP interaction with zero-valent iron nanoparticles (ZVI NPs), in aqueous media, was searched. The concentration of BNPP was 1000 times higher than the ZVI NPs concentration. The average size of the used iron nanoparticles was 10.2 ± 3.2 nm. The BNPP degradation process was monitored by means of UV-visible method. Initially, the BNPP hydrolysis happens through the P-O bonds breaking-off under the action of the ZVI NPs. Subsequently, the nitro groups were reduced to amine groups. The overall process takes place in 10 minutes. The reaction products were identified employing standard substances in adequate concentrations. The iron by-products were isolated and characterized by X-RD. These iron derivatives were identified as magnetite (Fe 3 O 4 ) and/or maghemite (γ-Fe 2 O 3 ) and lepidocrocite (γ-FeOOH). A suggested BNPP degradation mechanism will be discussed. (paper)

Impact of 13-Valent Pneumococcal Conjugate Vaccination in Invasive Pneumococcal Disease Incidence and Mortality

DEFF Research Database (Denmark)

Harboe, Zitta Barrella; Dalby, Tine; Weinberger, Daniel M

2014-01-01

BACKGROUND: The impact of the 13-valent pneumococcal conjugate vaccine (PCV13) at the population level is unclear. We explored PCV13's effect in reducing invasive pneumococcal disease (IPD)-related morbidity and mortality, and whether serotype-specific changes were attributable to vaccination or ...

Simple colorimetric assay for dehalogenation reactivity of nanoscale zero-valent iron using 4-chlorophenol

DEFF Research Database (Denmark)

Hwang, Yuhoon; Mines, Paul D.; Jakobsen, Mogens Havsteen

2015-01-01

Despite the wide application of nanoscale zero valent iron (nZVI) for the treatment of a plethora of pollutants through reductive reactions, reactivity evaluation of nZVI towards dehalogenation has not been standardized. In this light, it was desired to develop a simple colorimetric assay...

Background concentrations and reference values for heavy metals in soils of Cuba.

Science.gov (United States)

Alfaro, Mirelys Rodríguez; Montero, Alfredo; Ugarte, Olegario Muñiz; do Nascimento, Clístenes Williams Araújo; de Aguiar Accioly, Adriana Maria; Biondi, Caroline Miranda; da Silva, Ygor Jacques Agra Bezerra

2015-01-01

The potential threat of heavy metals to human health has led to many studies on permissible levels of these elements in soils. The objective of this study was to establish quality reference values (QRVs) for Cd, Pb, Zn, Cu, Ni, Cr, Fe, Mn, As, Hg, V, Ba, Sb, Ag, Co, and Mo in soils of Cuba. Geochemical associations between trace elements and Fe were also studied, aiming to provide an index for establishing background concentrations of metals in soils. Surface samples of 33 soil profiles from areas of native forest or minimal anthropic influence were collected. Samples were digested (USEPA method 3051A), and the metals were determined by ICP-OES. The natural concentrations of metals in soils of Cuba followed the order Fe > Mn > Ni > Cr > Ba > V > Zn > Cu > Pb > Co > As > Sb > Ag > Cd > Mo > Hg. The QRVs found for Cuban soils were as follows (mg kg(-1)): Ag (1), Ba (111), Cd (0.6), Co (25), Cr (153), Cu (83), Fe (54,055), Mn (1947), Ni (170), Pb (50), Sb (6), V (137), Zn (86), Mo (0.1), As (19), and Hg (0.1). The average natural levels of heavy metals are above the global average, especially for Ni and Cr. The chemical fractionation of soil samples presenting anomalous concentrations of metals showed that Cu, Ni, Cr, Sb, and As have low bioavailability. This suggests that the risk of contamination of agricultural products via plant uptake is low. However, the final decision on the establishment of soil QRVs in Cuba depends on political, economic, and social issues and in-depth risk analyses considering all routes of exposure to these elements.

Development of biomimetic catalytic oxidation methods and non-salt methods using transition metal-based acid and base ambiphilic catalysts

Science.gov (United States)

MURAHASHI, Shun-Ichi

2011-01-01

This review focuses on the development of ruthenium and flavin catalysts for environmentally benign oxidation reactions based on mimicking the functions of cytochrome P-450 and flavoenzymes, and low valent transition-metal catalysts that replace conventional acids and bases. Several new concepts and new types of catalytic reactions based on these concepts are described. PMID:21558760

Effects of ferrous ions on the reductive dechlorination of trichloroethylene by zero-valent iron

International Nuclear Information System (INIS)

Liu, C.-C.; Tseng, D.-H.; Wang, C.-Y.

2006-01-01

The surface characteristics of zero-valent iron (ZVI) and the efficiency of reductive dechlorination of trichloroethylene (TCE) in the presence of ferrous ions were studied. The experimental results indicated that the acid-washing of a metallic iron sample enhanced the efficiency of TCE degradation by ZVI. This occurred because acid-washing changed the conformation of oxides on the surface of iron from maghemite (γ-Fe 2 O 3 ) to the more hydrated goethite (α-FeOOH), as was confirmed by XPS analysis. However, when ferrous ions were simultaneous with TCE in water, the TCE degradation rate decreased as the concentration of ferrous ion increased. This was due to the formation of passive precipitates of ferrous hydroxide, including maghemite and magnetite (Fe 3 O 4 ), that coated on the surface of acid-washed ZVI, which as a result inhibited the electron transfer and catalytic hydrogenation mechanisms. On the other hand, in an Fe 0 -TCE system without the acid-washing pretreatment of ZVI, ferrous ions were adsorbed into the maghemite lattice which was then converted to semiconductive magnetite. Thus, the electrons were transferred from the iron surface and passed through the precipitates, allowing for the reductive dechlorination of TCE

Enhancement of aerobic granulation by zero-valent iron in sequencing batch airlift reactor

Energy Technology Data Exchange (ETDEWEB)

Kong, Qiang, E-mail: kongqiang0531@hotmail.com [College of Life Science, Shandong Normal University, 88 Wenhua Donglu, Jinan 250014, Shandong (China); Ngo, Huu Hao [School of Civil and Environmental Engineering, University of Technology Sydney, Broadway, NSW 2007 (Australia); Shu, Li [School of Engineering, Faculty of Science, Engineering and Built Environment, Deakin University, Geelong, Victoria 3216 (Australia); Fu, Rong-shu; Jiang, Chun-hui [College of Life Science, Shandong Normal University, 88 Wenhua Donglu, Jinan 250014, Shandong (China); Miao, Ming-sheng, E-mail: mingshengmiao@163.com [College of Life Science, Shandong Normal University, 88 Wenhua Donglu, Jinan 250014, Shandong (China)

2014-08-30

Highlights: • Zero-valent iron (ZVI) was used firstly to enhance the aerobic granulation. • ZVI significantly decreased the start-up time of the aerobic granulation. • ZVI had the function of enhancing organic material diversity identified by 3-D EEM. • ZVI could enhance the diversity of microbial community. - Abstract: This study elucidates the enhancement of aerobic granulation by zero-valent iron (ZVI). A reactor augmented with ZVI had a start-up time of aerobic granulation (43 days) that was notably less than that for a reactor without augmentation (64 days). The former reactor also had better removal efficiencies for chemical oxygen demand and ammonium. Moreover, the mature granules augmented with ZVI had better physical characteristics and produced more extracellular polymeric substances (especially of protein). Three-dimensional-excitation emission matrix fluorescence showed that ZVI enhanced organic material diversity. Additionally, ZVI enhanced the diversity of the microbial community. Fe{sup 2+} dissolution from ZVI helped reduce the start-up time of aerobic granulation and increased the extracellular polymeric substance content. Conclusively, the use of ZVI effectively enhanced aerobic granulation.

Enhancement of aerobic granulation by zero-valent iron in sequencing batch airlift reactor

International Nuclear Information System (INIS)

Kong, Qiang; Ngo, Huu Hao; Shu, Li; Fu, Rong-shu; Jiang, Chun-hui; Miao, Ming-sheng

2014-01-01

Highlights: • Zero-valent iron (ZVI) was used firstly to enhance the aerobic granulation. • ZVI significantly decreased the start-up time of the aerobic granulation. • ZVI had the function of enhancing organic material diversity identified by 3-D EEM. • ZVI could enhance the diversity of microbial community. - Abstract: This study elucidates the enhancement of aerobic granulation by zero-valent iron (ZVI). A reactor augmented with ZVI had a start-up time of aerobic granulation (43 days) that was notably less than that for a reactor without augmentation (64 days). The former reactor also had better removal efficiencies for chemical oxygen demand and ammonium. Moreover, the mature granules augmented with ZVI had better physical characteristics and produced more extracellular polymeric substances (especially of protein). Three-dimensional-excitation emission matrix fluorescence showed that ZVI enhanced organic material diversity. Additionally, ZVI enhanced the diversity of the microbial community. Fe 2+ dissolution from ZVI helped reduce the start-up time of aerobic granulation and increased the extracellular polymeric substance content. Conclusively, the use of ZVI effectively enhanced aerobic granulation

Reference Determinant Dependence of the Random Phase Approximation in 3d Transition Metal Chemistry.

Science.gov (United States)

Bates, J E; Mezei, P D; Csonka, G I; Sun, J; Ruzsinszky, A

2017-01-10

Without extensive fitting, accurate prediction of transition metal chemistry is a challenge for semilocal and hybrid density funcitonals. The Random Phase Approximation (RPA) has been shown to yield superior results to semilocal functionals for main group thermochemistry, but much less is known about its performance for transition metals. We have therefore analyzed the behavior of reaction energies, barrier heights, and ligand dissociation energies obtained with RPA and compare our results to several semilocal and hybrid functionals. Particular attention is paid to the reference determinant dependence of RPA. We find that typically the results do not vary much between semilocal or hybrid functionals as a reference, as long as the fraction of exact exchange (EXX) mixing in the hybrid functional is small. For large fractions of EXX mixing, however, the Hartree-Fock-like nature of the determinant can severely degrade the performance. Overall, RPA systematically reduces the errors of semilocal functionals and delivers excellent performance from a single reference determinant for inherently multireference reactions. The behavior of dual hybrids that combine RPA correlation with a hybrid exchange energy was also explored, but ultimately did not lead to a systematic improvement compared to traditional RPA for these systems. We rationalize this conclusion by decomposing the contributions to the reaction energies, and briefly discuss the possible implications for double-hybrid functionals based on RPA. The correlation between EXX mixing and spin-symmetry breaking is also discussed.

EFFICACY AND SAFETY OF 23-VALENT PNEUMOCOCCAL POLYSACCHARIDE VACCINE IN PATIENTS WITH RHEUMATOID ARTHRITIS

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M. S. Naumtseva

2015-01-01

Full Text Available Objective: to study the clinical efficacy, immunogenicity, and safety of a 23-valent pneumococcal vaccine in patients with rheumatoid arthritis (RA. Subjects and methods. The investigation enrolled 70 patients (55 women and 15 men aged 23–70 years, including 40 patients with RA and 30 people without systemic inflammatory rheumatic diseases (a control group who had a recent history of 2 and more cases of lower respiratory tract infections (bronchitis, pneumonia. When included, all the patients received anti-inflammatory therapy with methotrexate (MT (n = 24, leflunomide (LEF (n = 6, or MT + tumor necrosis factor-α (TNF-α inhibitors (n = 10. A single 0.5-ml dose of the 23-valent pneumococcal vaccine Pneumo-23 (Sanofi Pasteur was administered subcutaneously or intramuscularly during continuous MT or LEF therapy for the underlying disease or 3–4 weeks before the use of a TNF-α inhibitor. During control visits (1 and 3 months and 1 year after administration of the vaccine, the patients underwent physical examination and routine clinical and laboratory studies. Results. No clinical and radiological symptoms of pneumonia were recorded in any case during a 12-month follow-up. The RA and control groups showed a more than 2-fold increase in anti-pneumococcal antibody levels 1 year after vaccination. The vaccine was well tolerated by 50 patients. Sixteen patients were observed to have pain, cutaneous swelling and hyperemia and 4 had subfebrility. There were neither episodes of RA exacerbation nor new autoimmune disorders during the follow-up. Conclusion. The findings suggest that 23-valent pneumococcal vaccine shows a good clinical efficacy, adequate immunogenicity, and good tolerability in the patients with RA. 

Nanoporous networks as effective stabilisation matrices for nanoscale zero-valent iron and groundwater pollutant removal

DEFF Research Database (Denmark)

Mines, Paul D.; Byun, J.; Hwang, Yuhoon

2015-01-01

Nanoscale zero-valent iron (nZVI), with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants. Rapid aggregation and deactivation hinder its application in real-life conditions. Here, we show that by caging nZVI into the micropores of porous ...

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)/(III) composite

International Nuclear Information System (INIS)

Zboril, Radek; Andrle, Marek; Oplustil, Frantisek; Machala, Libor; Tucek, Jiri; Filip, Jan; Marusak, Zdenek; Sharma, Virender K.

2012-01-01

Highlights: ► Ferrate(VI) has been found to be highly efficient to decontaminate chemical warfare agents. ► Fast degradation of sulfur mustard, soman and compound VX by ferrate(VI). ► Nanoscale zero-valent iron particles are considerably less efficient in degradation of studied warfare agents compared to ferrate(VI). - Abstract: Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3′-imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants (∼10 −2 s −1 ) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10 −8 –10 −6 s −1 ). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs.

Development of biomimetic catalytic oxidation methods and non-salt methods using transition metal-based acid and base ambiphilic catalysts.

Science.gov (United States)

Murahashi, Shun-Ichi

2011-01-01

This review focuses on the development of ruthenium and flavin catalysts for environmentally benign oxidation reactions based on mimicking the functions of cytochrome P-450 and flavoenzymes, and low valent transition-metal catalysts that replace conventional acids and bases. Several new concepts and new types of catalytic reactions based on these concepts are described. (Communicated by Ryoji Noyori, M.J.A.).

Preparation and crystal structures of low-valent zirconocene complexes containing tetramethyl(phenyl) cyclopentadienyl ligands

Czech Academy of Sciences Publication Activity Database

Horáček, Michal; Pinkas, Jiří; Kubišta, Jiří; Císařová, I.; Gyepes, R.; Štěpnička, P.

2007-01-01

Roč. 72, 5-6 (2007), s. 679-696 ISSN 0010-0765 R&D Projects: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : metallocenes * zirconocenes * bis(trimethylsilyl)acetylene * low-valent zirconium complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.879, year: 2007

Synthesis and (spectro)electrochemistry of mixed-valent diferrocenyl-dihydrothiopyran derivatives.

Science.gov (United States)

Kowalski, Konrad; Karpowicz, Rafał; Mlostoń, Grzegorz; Miesel, Dominique; Hildebrandt, Alexander; Lang, Heinrich; Czerwieniec, Rafał; Therrien, Bruno

2015-04-07

Three novel diferrocenyl complexes were prepared and characterised. 2,2-Diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran (1, sulphide) was accessible by the hetero-Diels-Alder reaction of diferrocenyl thioketone with 2,3-dimethyl-1,3-butadiene. Stepwise oxidation of 1 gave the respective oxides 2,2-diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1-oxide (2, sulfoxide) and 2,2-diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1,1-dioxide (3, sulfone), respectively. The molecular structures of 1 and 3 in the solid state were determined by single crystal X-ray crystallography. The oxidation of sulphide 1 to sulfone 3, plays only a minor role on the overall structure of the two compounds. Electrochemical (cyclic voltammetry (= CV), square wave voltammetry (= SWV)) and spectroelectrochemical (in situ UV-Vis/NIR spectroscopy) studies were carried out. The CV and SWV measurements showed that an increase of the sulphur atom oxidation from -2 in 1 to +2 in 3 causes an anodic shift of the ferrocenyl-based oxidation potentials of about 100 mV. The electrochemical oxidation of 1-3 generates mixed-valent cations 1(+)-3(+). These monooxidised species display low-energy electronic absorption bands between 1000 and 3000 nm assigned to IVCT (= Inter-Valence Charge Transfer) electronic transitions. Accordingly, the mixed-valent cations 1(+)-3(+) are classified as weakly coupled class II systems according to Robin and Day.

Otitis media in children vaccinated during consecutive 7-valent or 10-valent pneumococcal conjugate vaccination schedules.

Science.gov (United States)

Leach, Amanda Jane; Wigger, Christine; Andrews, Ross; Chatfield, Mark; Smith-Vaughan, Heidi; Morris, Peter Stanley

2014-08-11

In 2001 when 7-valent pneumococcal conjugate vaccine (PCV7) was introduced, almost all (90%) young Australian Indigenous children living in remote communities had some form of otitis media (OM), including 24% with tympanic membrane perforation (TMP). In late 2009, the Northern Territory childhood vaccination schedule replaced PCV7 with 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10). We conducted regular surveillance of all forms of OM in children in remote Indigenous communities between September 2008 and December 2012. This analysis compares children less than 36 months of age who received a primary course of at least two doses of PCV7 or PHiD-CV10, and not more than one dose of another pneumococcal vaccine. Mean ages of 444 PCV7- and 451 PHiD-CV10-vaccinated children were 20 and 18 months, respectively. Bilaterally normal middle ears were detected in 7% and 9% respectively. OM with effusion was diagnosed in 41% and 51% (Risk Difference 10% [95% Confidence Interval 3 to 17] p = 0.002), any suppurative OM (acute OM or any TMP) in 51% versus 39% (RD -12% [95% CI -19 to -5] p = 0.0004], and TMP in 17% versus 14% (RD -3% [95% CI -8 to 2] p = 0.2), respectively. Multivariate analyses described a similar independent negative association between suppurative OM and PHiD-CV10 compared to PCV7 (Odds Ratio = 0.6 [95% CI 0.4 to 0.8] p = 0.001). Additional children in the household were a risk factor for OM (OR = 2.4 [95% CI 2 to 4] p = 0.001 for the third additional child), and older age and male gender were associated with less disease. Other measured risk factors were non-significant. Similar clinical results were found for children who had received non-mixed PCV schedules. Otitis media remains a significant health and social issue for Australian Indigenous children despite PCV vaccination. Around 90% of young children have some form of OM. Children vaccinated in with PHiD-CV10 had less suppurative OM than

Bioassessment of heavy metal toxicity and enhancement of heavy metal removal by sulfate-reducing bacteria in the presence of zero valent iron.

Science.gov (United States)

Guo, Jing; Kang, Yong; Feng, Ying

2017-12-01

A simple and valid toxicity evaluation of Zn 2+ , Mn 2+ and Cr 6+ on sulfate-reducing bacteria (SRB) and heavy metal removal were investigated using the SRB system and SRB+Fe 0 system. The heavy metal toxicity coefficient (β) and the heavy metal concentration resulting in 50% inhibition of sulfate reduction (I) from a modeling process were proposed to evaluate the heavy metal toxicity and nonlinear regression was applied to search for evaluation indices β and I. The heavy metal toxicity order was Cr 6+  > Mn 2+  > Zn 2+ . Compared with the SRB system, the SRB+Fe 0 system exhibited a better capability for sulfate reduction and heavy metal removal. The heavy metal removal was above 99% in the SRB+Fe 0 system, except for Mn 2+ . The energy-dispersive spectroscopy (EDS) analysis showed that the precipitates were removed primarily as sulfide for Zn 2+ and hydroxide for Mn 2+ and Cr 6+ .The method of evaluating the heavy metal toxicity on SRB was of great significance to understand the fundamentals of the heavy metal toxicity and inhibition effects on the microorganism and regulate the process of microbial sulfate reduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uranium Removal from Groundwater by Permeable Reactive Barrier with Zero-Valent Iron and Organic Carbon Mixtures: Laboratory and Field Studies

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Borys Kornilovych

2018-06-01

Full Text Available Zhovty Vody city, located in south-central Ukraine, has long been an important center for the Ukrainian uranium and iron industries. Uranium and iron mining and processing activities during the Cold War resulted in poorly managed sources of radionuclides and heavy metals. Widespread groundwater and surface water contamination has occurred, which creates a significant risk to drinking water supplies. Hydrogeologic and geochemical conditions near large uranium mine tailings storage facility (TSF were characterized to provide data to locate, design and install a permeable reactive barrier (PRB to treat groundwater contaminated by leachate infiltrating from the TSF. The effectiveness of three different permeable reactive materials was investigated: zero-valent iron (ZVI for reduction, sorption, and precipitation of redox-sensitive oxyanions; phosphate material to transform dissolved metals to less soluble phases; and organic carbon substrates to promote bioremediation processes. Batch and column experiments with Zhovty Vody site groundwater were conducted to evaluate reactivity of the materials. Reaction rates, residence time and comparison with site-specific clean-up standards were determined. Results of the study demonstrate the effectiveness of the use of the PRB for ground water protection near uranium mine TSF. The greatest decrease was obtained using ZVI-based reactive media and the combined media of ZVI/phosphate/organic carbon combinations.

Certification of a niobium metal reference material for neutron dosimetry (EC-NRM 525)

International Nuclear Information System (INIS)

Lievens, F.; Ingelbrecht, C.; Pauwels, J.

1990-01-01

Niobium metal, of 99.98% nominal purity, in the form of 0.02 and 0.1 mm thick foils and of 0.5 mm diameter wire, has been certified for its tantalum mass fraction. The certified value of the tantalum mass fraction is 19.6 ± 1.8 mg.kg -1 and is based on 71 results obtained by six laboratories by neutron activation analysis or inductively coupled plasma source mass spectrometry. The material is intended to be used as a reference material in neutron metrology

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)/(III) composite

Energy Technology Data Exchange (ETDEWEB)

Zboril, Radek, E-mail: zboril@prfnw.upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Andrle, Marek; Oplustil, Frantisek [Military Institute VOP-026 Sternberk, Division in Brno, Rybkova 8, 602 00 Brno (Czech Republic); Machala, Libor; Tucek, Jiri; Filip, Jan; Marusak, Zdenek [Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Sharma, Virender K., E-mail: vsharma@fit.edu [Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States); Center of Ferrate Excellence, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States)

2012-04-15

Highlights: Black-Right-Pointing-Pointer Ferrate(VI) has been found to be highly efficient to decontaminate chemical warfare agents. Black-Right-Pointing-Pointer Fast degradation of sulfur mustard, soman and compound VX by ferrate(VI). Black-Right-Pointing-Pointer Nanoscale zero-valent iron particles are considerably less efficient in degradation of studied warfare agents compared to ferrate(VI). - Abstract: Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Moessbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3 Prime -imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants ({approx}10{sup -2} s{sup -1}) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10{sup -8}-10{sup -6} s{sup -1}). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs.

Reference values for heavy metals in soils of the Brazilian agricultural frontier in Southwestern Amazônia.

Science.gov (United States)

dos Santos, Sabrina Novaes; Alleoni, Luís Reynaldo Ferracciú

2013-07-01

Guideline values are used to identify polluted or contaminated areas based on background values. Brazilian law establishes three guideline values for pollutants: a quality reference value (QRV), a prevention value, and an intervention value. Reference values refer to the natural concentration of an element or a substance in soils that have not been modified by anthropogenic impacts. These values inform assessments of soil quality and are used to establish maximum permissible limits. The objective of this study was to determine the natural levels and reference values for Cd, Co, Cr, Cu, Ni, Pb, and Zn in samples from the surface layer (0-20 cm) of 19 representative soils of the states of Mato Grosso and Rondônia, on Brazil's agricultural frontier. Pseudo-total metal concentrations were obtained following microwave-assisted digestion using the aqua regia and EPA3051 methods. QRVs were calculated for each element as the 75th and 90th percentiles of the frequency distribution of the data. Natural levels of heavy metals in the soil samples followed the order: Cr > Zn > Cu > Co > Pb > Ni > and Cd (aqua regia) and Cr > Co > Cu > Pb > Zn > Ni > Cd (EPA3051). These values are generally lower than those reported in the Brazilian and international literature, which highlights the importance of establishing reference values for each state or for each soil type, taking into account the geomorphological, pedological, and geological diversity of the region under study.

Effects of ferrous ions on the reductive dechlorination of trichloroethylene by zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Liu, C.-C. [Graduate Institute of Environmental Engineering, National Central University, Chungli, Taiwan 32001 (China); Tseng, D.-H. [Graduate Institute of Environmental Engineering, National Central University, Chungli, Taiwan 32001 (China)]. E-mail: dhtseng@ncuen.ncu.edu.tw; Wang, C.-Y. [Graduate Institute of Environmental Engineering, National Central University, Chungli, Taiwan 32001 (China)

2006-08-25

The surface characteristics of zero-valent iron (ZVI) and the efficiency of reductive dechlorination of trichloroethylene (TCE) in the presence of ferrous ions were studied. The experimental results indicated that the acid-washing of a metallic iron sample enhanced the efficiency of TCE degradation by ZVI. This occurred because acid-washing changed the conformation of oxides on the surface of iron from maghemite ({gamma}-Fe{sub 2}O{sub 3}) to the more hydrated goethite ({alpha}-FeOOH), as was confirmed by XPS analysis. However, when ferrous ions were simultaneous with TCE in water, the TCE degradation rate decreased as the concentration of ferrous ion increased. This was due to the formation of passive precipitates of ferrous hydroxide, including maghemite and magnetite (Fe{sub 3}O{sub 4}), that coated on the surface of acid-washed ZVI, which as a result inhibited the electron transfer and catalytic hydrogenation mechanisms. On the other hand, in an Fe{sup 0}-TCE system without the acid-washing pretreatment of ZVI, ferrous ions were adsorbed into the maghemite lattice which was then converted to semiconductive magnetite. Thus, the electrons were transferred from the iron surface and passed through the precipitates, allowing for the reductive dechlorination of TCE.

Removal of chromate in a permeable reactive barrier using zero-valent iron

DEFF Research Database (Denmark)

Kjeldsen, Peter; Locht, T

2002-01-01

Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces by the pre......). Mixing in sand had no significant enhancing effect on the removal capacity, in contrast to a pH adjustment of the groundwater to pH 4, which significantly increased the removal capacity....

Cadmium removal from aqueous solution by green synthesis zero valent silver nanoparticles with Benjamina leaves extract

Directory of Open Access Journals (Sweden)

Khairia M. Al-Qahtani

2017-12-01

Full Text Available Cadmium (II is an important element used in various industries, however, it is a poisonous element that affects the health of plants, animals and humans alike. It’s very important to remove this element from contaminated waters. This study aims at synthesizing zero valent silver nanoparticles by environmentally ecofriendly method without using hazardous compounds (via green approach. In this work, silver nanoparticles were prepared using hot water for the Ficus tree (Ficus Benjamina leaf extract (FBLE. The size of crystalline for AgNPs was measured by UV–vis spectroscopy and flourier transform infrared (FTIR. The properties of nano-silver particles (AgNPs have been studied using scanning electron microscope (SEM. The capability of nanoparticles to remove Cd2+ from contaminated solution was then studied. Parameter like adsorbent dose, heavy metal concentration, pH, agitation speed and contact time were studied. Cadmium removal increased when the dosage of biosorbent increases, pH increased from 1 to 6, contact time from 5 to 40 and initial concentration of Cd decrease. Isotherm adsorption was also described by the Freundleich model with a constant correlation (R2 higher than 0.973.

Granular activated carbon with grafted nanoporous polymer enhances nanoscale zero-valent iron impregnation and water contaminant removal

DEFF Research Database (Denmark)

Mines, Paul D.; Uthuppu, Basil; Thirion, Damien

2018-01-01

Granular activated carbon was customized with a chemical grafting procedure of a nanoporous polymeric network for the purpose of nanoscale zero-valent iron impregnation and subsequent water contaminant remediation. Characterization of the prepared composite material revealed that not only was the...

Inhibiting excessive acidification using zero-valent iron in anaerobic digestion of food waste at high organic load rates.

Science.gov (United States)

Kong, Xin; Wei, Yonghong; Xu, Shuang; Liu, Jianguo; Li, Huan; Liu, Yili; Yu, Shuyao

2016-07-01

Excessive acidification occurs frequently in food waste (FW) anaerobic digestion (AD) due to the high carbon-to-nitrogen ratio of FW. In this study, zero-valent iron (ZVI) was applied to prevent the excessive acidification. All of the control groups, without ZVI addition (pH∼5.3), produced little methane (CH4) and had high volatile fatty acids/bicarbonate alkalinity (VFA/ALK). By contrast, at OLR of 42.32gVS/Lreactor, the pH of effluent from the reactors with 0.4g/gVSFWadded of ZVI increased to 7.8-8.2, VFA/ALK decreased to <0.1, and the final CH4 yield was ∼380mL/gVSFWadded, suggesting inhibition of excessive acidification. After adding powdered or scrap metal ZVI to the acidogenic reactors, the fractional content of butyric acid changed from 30-40% to 0%, while, that of acetic acid increased. These results indicate that adding ZVI to FW digestion at high OLRs could eliminate excessive acidification by promoting butyric acid conversion and enhancing methanogen activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of Cr(VI from Water Using a New Reactive Material: Magnesium Oxide Supported Nanoscale Zero-Valent Iron

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Alessio Siciliano

2016-08-01

Full Text Available The chromium pollution of water is an important environmental and health issue. Cr(VI removal by means of metallic iron is an attractive method. Specifically, nanoscopic zero valent iron (NZVI shows great reactivity, however, its applicability needs to be further investigated. In the present paper, NZVI was supported on MgO grains to facilitate the treatments for remediation of chromium-contaminated waters. The performances and mechanisms of the developed composite, in the removal of hexavalent chromium, were investigated by means of batch and continuous tests. Kinetic studies, under different operating conditions, showed that reduction of Cr(VI could be expressed by a pseudo second-order reaction kinetic. The reaction rate increased with the square of Fe(0 amount, while it was inversely proportional to the initial chromium concentration. The process performance was satisfactory also under uncontrolled pH, and a limited influence of temperature was observed. The reactive material was efficiently reusable for many cycles without any regeneration treatment. The performances in continuous tests were close to 97% for about 80 pore volume of reactive material.

Pneumococcal meningitis: epidemiological profile pre‐ and post‐introduction of the pneumococcal 10‐valent conjugate vaccine

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Tatiane E. Hirose

2015-03-01

Conclusion: Even after a short time of use, the 10‐valent pneumococcal conjugate vaccine has already had a significant impact in reducing the incidence and mortality of meningitis cases among infants, as well as the reduction of cases whose serotypes are included in the vaccine.

Microwave-assisted McMurry polymerization utilizing low-valent titanium for the synthesis of poly 2,6-[1,5-bis(dodecyloxy)naphthylene vinylene] (PNV)

DEFF Research Database (Denmark)

Thomas, Henrik; Stuhr-Hansen, Nicolai; Westerlund, Fredrik

2009-01-01

Poly 2,6-[1,5-bis(dodecyloxy)naphthylene vinylene] is synthesized by microwave-assisted McMurry polymerization utilizing low-valent titanium generated from titanium tetrachloride and zinc. The obtained polymer is fluorescent with an average molecular weight of approximately 65,000 g/mol and a pol......Poly 2,6-[1,5-bis(dodecyloxy)naphthylene vinylene] is synthesized by microwave-assisted McMurry polymerization utilizing low-valent titanium generated from titanium tetrachloride and zinc. The obtained polymer is fluorescent with an average molecular weight of approximately 65,000 g...

The recent development of efficient Earth-abundant transition-metal nanocatalysts.

Science.gov (United States)

Wang, Dong; Astruc, Didier

2017-02-06

Whereas noble metal compounds have long been central in catalysis, Earth-abundant metal-based catalysts have in the same time remained undeveloped. Yet the efficacy of Earth-abundant metal catalysts was already shown at the very beginning of the 20th century with the Fe-catalyzed Haber-Bosch process of ammonia synthesis and later in the Fischer-Tropsch reaction. Nanoscience has revolutionized the world of catalysis since it was observed that very small Au nanoparticles (NPs) and other noble metal NPs are extraordinarily efficient. Therefore the development of Earth-abundant metals NPs is more recent, but it has appeared necessary due to their "greenness". This review highlights catalysis by NPs of Earth-abundant transition metals that include Mn, Fe, Co, Ni, Cu, early transition metals (Ti, V, Cr, Zr, Nb and W) and their nanocomposites with emphasis on basic principles and literature reported during the last 5 years. A very large spectrum of catalytic reactions has been successfully disclosed, and catalysis has been examined for each metal starting with zero-valent metal NPs followed by oxides and other nanocomposites. The last section highlights the catalytic activities of bi- and trimetallic NPs. Indeed this later family is very promising and simultaneously benefits from increased stability, efficiency and selectivity, compared to monometallic NPs, due to synergistic substrate activation.

Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

Science.gov (United States)

Quinn, Jacqueline; Geiger, Cherie; Clausen, Christian

2013-01-01

Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. The mechanical milling technique is

Source zone remediation by zero valent iron technologies

DEFF Research Database (Denmark)

Fjordbøge, Annika Sidelmann

at a fifth of these contaminated sites. These source zones pose a serious threat to soil and groundwater quality. Remediation of the heterogeneous source zones is challenging due to irregular downwards migration patterns in the subsurface, low aqueous solubility and matrix diffusion. To protect the soil...... and groundwater resources from long-term deterioration, the development of in situ technologies suitable for remediation of DNAPL is warranted. Currently, an array of aggressive in situ remediation technologies remediation exists. These technologies may be suitable under various site specific conditions; however......, most of them are limited by subsurface heterogeneities and/or the risk of inadvertent DNAPL displacement during field application. This thesis presents the results of an investigation of the potential for remediation of chlorinated solvent source zones by emerging zero valent iron (ZVI) based...

In field arsenic removal from natural water by zero-valent iron assisted by solar radiation

International Nuclear Information System (INIS)

Cornejo, Lorena; Lienqueo, Hugo; Arenas, Maria; Acarapi, Jorge; Contreras, David; Yanez, Jorge; Mansilla, Hector D.

2008-01-01

An in situ arsenic removal method applicable to highly contaminated water is presented. The method is based in the use of steel wool, lemon juice and solar radiation. The method was evaluated using water from the Camarones River, Atacama Desert in northern Chile, in which the arsenic concentration ranges between 1000 and 1300 μg L -1 . Response surface method analysis was used to optimize the amount of zero-valent iron (steel wool) and the citrate concentration (lemon juice) to be used. The optimal conditions when using solar radiation to remove arsenic from natural water from the Camarones river are: 1.3 g L -1 of steel wool and one drop (ca. 0.04 mL) of lemon juice. Under these conditions, removal percentages are higher than 99.5% and the final arsenic concentration is below 10 μg L -1 . This highly effective arsenic removal method is easy to use and inexpensive to implement. - An in situ arsenic removal method applicable to highly contaminated waters by using zero-valent iron, citrate and solar radiation was developed

In field arsenic removal from natural water by zero-valent iron assisted by solar radiation

Energy Technology Data Exchange (ETDEWEB)

Cornejo, Lorena [Departamento de Quimica, Facultad de Ciencias, Universidad de Tarapaca, Casilla 7-D, Arica (Chile); Laboratorio de Investigaciones Medioambientales de Zonas Aridas, LIMZA, Centro de Investigaciones del Hombre en el Desierto, CIHDE, Arica (Chile)], E-mail: lorenacp@uta.cl; Lienqueo, Hugo; Arenas, Maria [Departamento de Quimica, Facultad de Ciencias, Universidad de Tarapaca, Casilla 7-D, Arica (Chile); Acarapi, Jorge [Departamento de Quimica, Facultad de Ciencias, Universidad de Tarapaca, Casilla 7-D, Arica (Chile); Laboratorio de Investigaciones Medioambientales de Zonas Aridas, LIMZA, Centro de Investigaciones del Hombre en el Desierto, CIHDE, Arica (Chile); Contreras, David; Yanez, Jorge; Mansilla, Hector D. [Facultad de Ciencias Quimicas, Universidad de Concepcion, Casilla 160C, Concepcion (Chile)

2008-12-15

An in situ arsenic removal method applicable to highly contaminated water is presented. The method is based in the use of steel wool, lemon juice and solar radiation. The method was evaluated using water from the Camarones River, Atacama Desert in northern Chile, in which the arsenic concentration ranges between 1000 and 1300 {mu}g L{sup -1}. Response surface method analysis was used to optimize the amount of zero-valent iron (steel wool) and the citrate concentration (lemon juice) to be used. The optimal conditions when using solar radiation to remove arsenic from natural water from the Camarones river are: 1.3 g L{sup -1} of steel wool and one drop (ca. 0.04 mL) of lemon juice. Under these conditions, removal percentages are higher than 99.5% and the final arsenic concentration is below 10 {mu}g L{sup -1}. This highly effective arsenic removal method is easy to use and inexpensive to implement. - An in situ arsenic removal method applicable to highly contaminated waters by using zero-valent iron, citrate and solar radiation was developed.

Data of furfural adsorption on nano zero valent iron (NZVI synthesized from Nettle extract

Directory of Open Access Journals (Sweden)

Mehdi Fazlzadeh

2018-02-01

Full Text Available Among various water and wastewater treatment methods, adsorption techniques are widely used to remove certain classes of pollutants due to its unique features. Thus, the aim of this data article is to synthesize zero valent iron nanoparticles (NZVI from Nettle leaf extract by green synthesis method as an environmentally friendly technique, and to evaluate it's efficiency in the removal of furfural from aqueous solutions. The data of possible adsorption mechanism and isotherm of furfural on the synthesized adsorbent are depicted in this data article. The data acquired showed that the adsorption trend follows the pseudo-second order kinetic model and that the Langmuir isotherm was suitable for correlation of equilibrium data with the maximum adsorption capacity of 454.4 mg/g. The information of initial furfural concentration, pH, adsorbent dosage and contact time effects on the removal efficiency are presented. Considering the findings data, the developed nanoparticle from Nettle leaf extract, as a low cost adsorbent, could be considered as promising adsorbent for furfural and probably similar organic pollutants removal from aqueous solutions. Keywords: Green synthesis method, Furfural, Nettle zero valent iron nanoparticles (NNZVI, Low cost adsorbents

Is 13-Valent Pneumococcal Conjugate Vaccine (PCV13 Combined With 23-Valent Pneumococcal Polysaccharide Vaccine (PPSV23 Superior to PPSV23 Alone for Reducing Incidence or Severity of Pneumonia in Older Adults? A Clin-IQ

Directory of Open Access Journals (Sweden)

Starla Hayward

2016-04-01

Full Text Available Pneumonia infection is a significant cause of morbidity and mortality worldwide. In addition to the public health concerns, pneumonia also accounts for a significant cost to the health care system. Currently there are two leading vaccines targeted against Streptococcus pneumoniae: 23-valent pneumococcal polysaccharide vaccine (PPSV23 and 13-valent pneumococcal conjugate vaccine (PCV13. Until recently, the recommendation for adult pneumonia vaccination has been a single dose of PPSV23 for all adults aged 65 years or older. However, concerns were raised regarding the vaccine’s efficacy due to the persistent burden of pneumococcal disease in the elderly population. This paper focuses on two trials that evaluated the safety and efficacy of PCV13 in the adult population. The first study reveals improved immune response with the addition of PCV13 to PPSV23, while the second shows PCV13 was effective in the prevention of vaccine-type community-acquired pneumonia. Both studies observed adequate safety profiles for PCV13 in series with PPSV23 and with PCV13 compared to placebo.

Antigen-specific IgA titres after 23-valent pneumococcal vaccine indicate transient antibody deficiency disease in children

NARCIS (Netherlands)

Janssen, Willemijn J M; Nierkens, Stefan; Sanders, Elisabeth A; Boes, Marianne; van Montfrans, Joris M

2015-01-01

Paediatric patients with antibody deficiency may either be delayed in development of humoral immunity or may be persistently deficient in antibody production. To differentiate between these entities, we examined the 23-valent pneumococcal polysaccharide (PnPS) vaccine-induced IgM-, IgG- and IgA

Zero-valent iron particles embedded on the mesoporous silica–carbon for chromium (VI) removal from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Xiong, Kun, E-mail: kunxiong312@gmail.com; Gao, Yuan [Chongqing Technology and Business University, Engineering Research Center for Waste Oil Recovery Technology and Equipment of Ministry of Education, Chongqing Key Laboratory of Catalysis & Environmental New Materials (China); Zhou, Lin [Chengdu Radio and TV University (China); Zhang, Xianming [Chongqing Technology and Business University, Engineering Research Center for Waste Oil Recovery Technology and Equipment of Ministry of Education, Chongqing Key Laboratory of Catalysis & Environmental New Materials (China)

2016-09-15

Nanoscale zero-valent iron (nZVI) particles were embedded on the walls of mesoporous silica–carbon (MSC) under the conditions of high-temperature carbonization and reduction and used to remove chromium (VI) from aqueous solution. The structure and textural properties of nZVI–MSC were characterized by the powder X-ray diffraction, transmission electron microscopy and N{sub 2} adsorption and desorption. The results show that nZVI–MSC has highly ordered mesoporous structure and large surface area, indistinguishable with that of MSC. Compared with the support MSC and iron particles supported on the activated carbon (nZVI/AC), nZVI–MSC exhibited much higher Cr(VI) removal efficiency with about 98 %. The removal process obeys a pseudo first-order model. Such excellent performance of nZVI–MSC could be ascribed to the large surface and iron particles embedded on the walls of the MSC, forming an intimate contact with the MSC. It is proposed that this feature might create certain micro-electrode on the interface of iron particles and MSC, which prevented the formation of metal oxide on the surface and provided fresh Fe surface for Cr(VI) removal.

Merging Visible Light Photoredox Catalysis with Metal Catalyzed C–H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants

KAUST Repository

Fabry, David C.; Rueping, Magnus

2016-01-01

ConspectusThe development of efficient catalytic systems for direct aromatic C-H bond functionalization is a long-desired goal of chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies for C-C and C-heteroatom bond formation. A key challenge for these transformations is the reoxidation of the in situ generated metal hydride or low-valent metal complexes of the primary catalytic bond forming cycle. To complete the catalytic cycle and to regenerate the C-H activation catalyst, (super)stoichiometric amounts of Cu(II) or Ag(I) salts have often been applied. Recently,

Merging Visible Light Photoredox Catalysis with Metal Catalyzed C–H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants

KAUST Repository

Fabry, David C.

2016-08-24

ConspectusThe development of efficient catalytic systems for direct aromatic C-H bond functionalization is a long-desired goal of chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies for C-C and C-heteroatom bond formation. A key challenge for these transformations is the reoxidation of the in situ generated metal hydride or low-valent metal complexes of the primary catalytic bond forming cycle. To complete the catalytic cycle and to regenerate the C-H activation catalyst, (super)stoichiometric amounts of Cu(II) or Ag(I) salts have often been applied. Recently,

Immunogenicity and Immunological Memory Induced by the 13-Valent Pneumococcal Conjugate Followed by the 23-Valent Polysaccharide Vaccine in HIV-Infected Adults.

Science.gov (United States)

Farmaki, Paraskevi F; Chini, Maria C; Mangafas, Nikolaos M; Tzanoudaki, Marianna T; Piperi, Christina P; Lazanas, Marios Z; Spoulou, Vana S

2018-05-02

Vaccine-induced memory B-cell (MBC) subsets have distinct roles in the establishment of protective immunity; MBCs expressing nonswitched immunoglobulin M (IgM+ MBCs) replenish the MBC pool, whereas MBCs expressing isotype-switched immunoglobulin (sIg+ MBCs) differentiate into plasma cells upon antigen reencounter. We investigated immunogenicity and MBCs induced by combined 13-valent pneumococcal conjugate vaccine (PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPV23) in human immunodeficiency virus (HIV)-infected adults. Forty HIV-seropositive adults receiving ART with undetectable viral loads were enrolled. Seventeen had a CD4+ T-cell count of ≥400 cells/μL (group A), and 23 had a CD4+ T-cell count of 200-399 cells/μL (group B). All adults received PCV13 and, 1 year later, PPV23. Levels of IgM+ MBCs (defined as polysaccharide [PS]-specific CD19+CD10-CD27+CD21++IgM+ MBCs) and sIg+ MBCs (defined as PS-specific CD19+CD10-CD27+CD21++IgM- MBCs) and antibodies against PS14 and PS3 were measured prior and 1 month after each vaccination. Immunization caused a significant increase in PS antibodies, compared with levels at baseline (P < .001). Group B achieved significantly lower titers than group A (P < .05 for both PS14 and PS3). After receipt of PCV13, levels of IgM+ MBCs were unchanged, whereas levels of sIg+ MBCs increased significantly (P < .05 for PS14 and P < .001 for PS3). In contrast, following PPV23 receipt, levels of IgM+ MBCs were significantly reduced, and levels of sIg+ MBCs remained stable. A positive correlation was observed between baseline IgM+ and sIg+ MBC counts 1 month after PCV13 receipt but not after PPV23 receipt. PPV23 receipt 12 months after PCV13 receipt improved PCV13 immunogenicity. The reduction in the IgM+ MBC count observed after PPV23 receipt suggests that PPV23 has a depleting effect on PCV13-associated immunological memory. NCT03041051.

The effect of ascorbic acid-stabilized zero valent iron nanoparticles on the distribution of different forms of cadmium in three spiked soils

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Mohaddese Savasari

2017-01-01

Full Text Available Introduction: Increases in pollution of water resources due to the contaminants have made researchers to develop the various methods in the remediation and the reuses of polluted resources contamination of soils with heavy metals is one of great environmental concerns for the human beings. Cadmium (Cd as a toxic heavy metal is of significant environmental and occupational concern. Contamination of soils with heavy metals is one of great environmental concerns for the human beings. The numbers of sorbents that have been used for Cd (II reductive removal are biopolymers, fly ash, activated carbon, metal oxides, clays, zeolites, dried plant parts, microorganisms, and sewage sludge. However, most of the mentioned sorbents had limitations of cost and durability that call a needed approach by cost effective remediation technique with high efficiency. Application of zero valent iron nanoparticles (ZVINs as a promising technique for remediation of heavy metals are being increasingly considered by researchers. This study was conducted to synthesis and characterize the ZVINs stabilized with ascorbic acid (AAS - ZVIN in aerobic conditions and to assess their ability for removal efficiency of cadmium (Cd from the soils and changes in different fraction of Cd in three spiked soils including sandy, acidity and calcareous soils were also studied. Materials and Methods: The stabilized ZVINs were prepared in cold distilled water by reducing Fe (III to Fe0 using sodium borohydride in the presence of ascorbic acid as stabilizer and reducing agent. The freshly synthesized AAS-ZVIN washed three times and then used for the subsequent analysis. Characterization of the synthesized AAS-ZVIN was carried out by scanning electron microscope (SEM. X-ray diffraction (XRD was performed using a Philips D500 diffract meter with Ni-filtered Cu ka radiation. To determine the availability of Cd, the DTPA-extractable amounts of Cd in the spiked soils so sandy, acid and calcareous

Immunogenicity and safety of a booster dose of the 13-valent pneumococcal conjugate vaccine in children primed with the 10-valent or 13-valent pneumococcal conjugate vaccine in the Czech Republic and Slovakia.

Science.gov (United States)

Urbancikova, Ingrid; Prymula, Roman; Goldblatt, David; Roalfe, Lucy; Prymulova, Karolina; Kosina, Pavel

2017-09-12

Although both the 13-valent pneumococcal conjugate vaccine (PCV13) and the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) are widely used, it is unclear how interchangeable they are in terms of immunogenicity. Two phase 3, open-label, multicenter studies were conducted to assess the immunogenicity and safety of a booster dose of PCV13 in children primed with PHiD-CV or PCV13. In the Czech Republic, 12-15-month-old children received a PCV13 booster after 3-dose priming with either PHiD-CV or PCV13. In Slovakia, 11-12-month-old children received PCV13 following 2-dose priming with either PHiD-CV or PCV13. Serum IgG concentrations were assessed by enzyme-linked immunosorbent assay and functional antibodies were assessed by opsonophagocytic assay (OPA) before the booster and at 1 and 12months afterward. The primary objective of these studies was to assess non-inferiority of OPA titers for serotype 19A in PHiD-CV-primed subjects compared to those in PCV13-primed children 1month post-booster. A total of 98 subjects in the Czech Republic and 89 subjects in Slovakia were included. One month after the PCV13 booster dose, the IgG and OPA immune responses to serotype 19A in subjects primed with 2 or 3 doses of PHiD-CV were non-inferior to those in subjects primed with PCV13. Non-inferior and persistent immune responses to most other vaccine serotypes were also observed after the PCV13 booster in PHiD-CV-primed subjects. No safety issues were raised in either study. Overall, robust IgG and OPA immunological responses were observed after booster vaccination with PCV13 in children primed with 2 or 3 doses of PHiD-CV or PCV13, including for serotypes not included in PHiD-CV. These results suggest that these vaccines are interchangeable in terms of safety and immunogenicity and that PCV13 can be used as a booster in the context of mixed schedules. (EudraCT numbers: 2012-005366-35 and 2012-005367-27). Copyright © 2017 Elsevier Ltd

Cost-effectiveness analysis of a universal vaccination programme with the 7-valent pneumococcal conjugate vaccine (PCV-7) in Sweden

DEFF Research Database (Denmark)

Bergman, Annika; Hjelmgren, Jonas; Ortqvist, Ake

2008-01-01

The 7-valent pneumococcal conjugate vaccine (PCV-7) has proved to be highly effective against invasive pneumococcal disease and has also provided some protection against all-cause pneumonia and acute otitis media. The objective of this study was to evaluate the projected health benefits, costs...... of pneumococcal septicaemia among adults. The incremental cost per QALY and LY gained was estimated to Euro 29,200 and Euro 51,400, respectively. When herd immunity was accounted for, the cost per QALYand LY gained was estimated to Euro 5500 and Euro 6600, respectively. Thus, the health benefits of a national...... and cost-effectiveness of vaccination with the 7-valent conjugated pneumococcal vaccine compared with no vaccination, in all infants in Sweden, taking herd immunity into account. A Markov model was used and a hypothetical birth cohort was simulated for a lifelong perspective. The results show...

El vacío como fenómeno estético-religioso en la obra de José Ángel Valente

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Guillermo Aguirre-Martínez

2015-09-01

Full Text Available Un espacio carente de dimensiones y de contenido podrá observarse a modo de límite primero y último en la poesía de José Ángel Valente. De este modo, a un vacío inicial del que surgirá la creación poética, le corresponderá, en su otro extremo, un margen igualmente carente de medida y de sustancia al que se arrojará la palabra poética en su búsqueda de un orden trascendental. El vacío –la nada, lo indefinido–, se constituirá como polo de atracción de una poesía cuyas formalizaciones participan de una serie de metamorfosis que, a modo de escala, permiten el desplazamiento de las imágenes entre los dos límites que componen el espacio creativo del autor. Las siguientes páginas estudiarán la función y el valor de este espacio libre de formas en la obra lírica de José Ángel Valente. This study focuses on the role and value of void and silence in José Ángel Valente’s poetry. In this light, the void can be seen as the origin and end of Valente’s work. On the one hand, the void signals the source from which the poetic word grows. On the other, it refers to the kind of emptiness characteristic of a sacred space in a transcendental order. In this way, the notion of void, silence, or nothingness can be viewed as a double pole of attraction whose boundaries reflect the movement of the poetic word. Considering its spiritual nature, this word undergoes a series of metamorphoses between these two poles.

Impact of Subsurface Heterogeneities on nano-Scale Zero Valent Iron Transport

Science.gov (United States)

Krol, M. M.; Sleep, B. E.; O'Carroll, D. M.

2011-12-01

Nano-scale zero valent iron (nZVI) has been applied as a remediation technology at sites contaminated with chlorinated compounds and heavy metals. Although laboratory studies have demonstrated high reactivity for the degradation of target contaminants, the success of nZVI in the field has been limited due to poor subsurface mobility. When injected into the subsurface, nZVI tends to aggregate and be retained by subsurface soils. As such nZVI suspensions need to be stabilized for increased mobility. However, even with stabilization, soil heterogeneities can still lead to non-uniform nZVI transport, resulting in poor distribution and consequently decreased degradation of target compounds. Understanding how nZVI transport can be affected by subsurface heterogeneities can aid in improving the technology. This can be done with the use of a numerical model which can simulate nZVI transport. In this study CompSim, a finite difference groundwater model, is used to simulate the movement of nZVI in a two-dimensional domain. CompSim has been shown in previous studies to accurately predict nZVI movement in the subsurface, and is used in this study to examine the impact of soil heterogeneity on nZVI transport. This work also explores the impact of different viscosities of the injected nZVI suspensions (corresponding to different stabilizing polymers) and injection rates on nZVI mobility. Analysis metrics include travel time, travel distance, and average nZVI concentrations. Improving our understanding of the influence of soil heterogeneity on nZVI transport will lead to improved field scale implementation and, potentially, to more effective remediation of contaminated sites.

Fekete-Szegö inequalities for p-valent starlike and convex functions of complex order

Directory of Open Access Journals (Sweden)

M.K. Aouf

2014-07-01

Full Text Available In this paper, we obtain Fekete-Szegö inequalities for certain class of analytic p-valent functions f(z for which 1+1b1pz(f∗g′(z+λz2(f∗g″(z(1-λ(f∗g(z+λz(f∗g′(z-1≺φ(z(b∈C∗=C⧹{0}. Sharp bounds for the Fekete-Szegö functional |ap+2-μap+12| are obtained.

Biosorbents for Removing Hazardous Metals and Metalloids

Directory of Open Access Journals (Sweden)

Katsutoshi Inoue

2017-07-01

Full Text Available Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II, Cr(VI, Sb(III and V, and As(III and V were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II. Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide into biosorbents that effectively removed Pb(II. These materials also effectively removed Sb(III and V and As(III and V when these were preloaded with multi-valent metal ions such as Zr(IV and Fe(III. Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI, were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid.

Data of furfural adsorption on nano zero valent iron (NZVI) synthesized from Nettle extract

OpenAIRE

Fazlzadeh, Mehdi; Ansarizadeh, Mohammad; Leili, Mostafa

2017-01-01

Among various water and wastewater treatment methods, adsorption techniques are widely used to remove certain classes of pollutants due to its unique features. Thus, the aim of this data article is to synthesize zero valent iron nanoparticles (NZVI) from Nettle leaf extract by green synthesis method as an environmentally friendly technique, and to evaluate it's efficiency in the removal of furfural from aqueous solutions. The data of possible adsorption mechanism and isotherm of furfural on t...

Immunogenicity and Safety of the 13-Valent Pneumococcal Conjugate Vaccine versus the 23-Valent Polysaccharide Vaccine in Unvaccinated HIV-Infected Adults: A Pilot, Prospective Controlled Study.

Directory of Open Access Journals (Sweden)

Francesca Lombardi

Full Text Available Definition of the optimal pneumococcal vaccine strategy in HIV-infected adults is still under evaluation. We aimed to compare immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine (PCV13 versus the 23-valent polysaccharide vaccine (PPSV23 in HIV-infected adults.We performed a pilot, prospective controlled study enrolling HIV-infected pneumococcal vaccine-naïve outpatients, aged 18-65 years with CD4 counts ≥200 cells/μL. Eligible subjects were recruited into two parallel groups: group 1 (n = 50 received two doses of PCV13 eight weeks apart, and group 2 (n = 50 received one dose of PPSV23, as part of their standard of care. Anti-pneumococcal capsular polysaccharide immunoglobulin G concentrations were quantified by ELISA at baseline, 8, 24 and 48 weeks. Clinical and viro-immunological follow-up was performed at the same time points. Unvaccinated, age-matched HIV-negative adults (n = 100 were also enrolled as baseline controls.Pre-vaccination specific IgG titers for each pneumococcal antigen did not differ between study groups but they were constantly lower than those from the HIV-negative controls. After immunization, significant increases in IgG titers were observed in both study groups at each time point compared to baseline, but response to serotype 3 was blunted in group 1. Antibody titers for each antigen did not differ between study groups at week 48. Overall, the proportion of subjects achieving seroprotection and seroconversion to all serotypes was comparable between groups. A marked decrease in IgG levels over time was observed with both vaccines. No relevant adverse reactions were reported in either group.In this population with favorable immune profile, no relevant differences were observed in immunogenicity between PCV13 and PPSV23. Both vaccines were safe and well tolerated.ClinicalTrials.gov NCT02123433.

Evaluation of reference genes for RT-qPCR study in abalone Haliotis discus hannai during heavy metal overload stress

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Sang Yoon Lee

2016-06-01

Full Text Available Abstract Background The evaluation of suitable reference genes as normalization controls is a prerequisite requirement for launching quantitative reverse transcription-PCR (RT-qPCR-based expression study. In order to select the stable reference genes in abalone Haliotis discus hannai tissues (gill and hepatopancreas under heavy metal exposure conditions (Cu, Zn, and Cd, 12 potential candidate housekeeping genes were subjected to expression stability based on the comprehensive ranking while integrating four different statistical algorithms (geNorm, NormFinder, BestKeeper, and ΔCT method. Results Expression stability in the gill subset was determined as RPL7 > RPL8 > ACTB > RPL3 > PPIB > RPL7A > EF1A > RPL4 > GAPDH > RPL5 > UBE2 > B-TU. On the other hand, the ranking in the subset for hepatopancreas was RPL7 > RPL3 > RPL8 > ACTB > RPL4 > EF1A > RPL5 > RPL7A > B-TU > UBE2 > PPIB > GAPDH. The pairwise variation assessed by the geNorm program indicates that two reference genes could be sufficient for accurate normalization in both gill and hepatopancreas subsets. Overall, both gill and hepatopancreas subsets recommended ribosomal protein genes (particularly RPL7 as stable references, whereas traditional housekeepers such as β-tubulin (B-TU and glyceraldehyde-3-phosphate dehydrogenase (GAPDH genes were ranked as unstable genes. The validation of reference gene selection was confirmed with the quantitative assay of MT transcripts. Conclusions The present analysis showed the importance of validating reference genes with multiple algorithmic approaches to select genes that are truly stable. Our results indicate that expression stability of a given reference gene could not always have consensus across tissue types. The data from this study could be a good guide for the future design of RT-qPCR studies with respect to metal regulation/detoxification and other related

Nationwide Trends in Bacterial Meningitis before the Introduction of 13-Valent Pneumococcal Conjugate Vaccine—Burkina Faso, 2011–2013

Science.gov (United States)

Ouédraogo-Traoré, Rasmata; Medah, Isaïe; Sangare, Lassana; Yaméogo, Issaka; Sawadogo, Guetawendé; Ouédraogo, Abdoul-Salam; Hema-Ouangraoua, Soumeya; McGee, Lesley; Srinivasan, Velusamy; Aké, Flavien; Congo-Ouédraogo, Malika; Sanou, Soufian; Ba, Absatou Ky; Novak, Ryan T.; Van Beneden, Chris

2016-01-01

Background Following introduction of Haemophilus influenzae type b vaccine in 2006 and serogroup A meningococcal conjugate vaccine in 2010, Streptococcus pneumoniae (Sp) became the leading cause of bacterial meningitis in Burkina Faso. We describe bacterial meningitis epidemiology, focusing on pneumococcal meningitis, before 13-valent pneumococcal conjugate vaccine (PCV13) introduction in the pediatric routine immunization program in October 2013. Methods Nationwide population-based meningitis surveillance collects case-level demographic and clinical information and cerebrospinal fluid (CSF) laboratory results. Sp infections are confirmed by culture, real-time polymerase chain reaction (rt-PCR), or latex agglutination, and CSF serotyped using real-time and conventional PCR. We calculated incidence rates in cases per 100,000 persons, adjusting for age and proportion of cases with CSF tested at national reference laboratories, and case fatality ratios (CFR). Results During 2011–2013, 1,528 pneumococcal meningitis cases were reported. Average annual adjusted incidence rates were 26.9 (meningitis occurred among children aged <1 year. The majority of cases were due to PCV13-associated serotypes; introduction of PCV13 should substantially decrease this burden. PMID:27832151

Impurity model for mixed-valent Mn3+/Mn4+ ions

International Nuclear Information System (INIS)

Schlottmann, P.; Lee, K.

1997-01-01

Intermediate valent tri- and tetravalent manganese ions play an important role in LaMnO 3 -based systems. We consider a Mn impurity with five orbitals in cubic symmetry which hybridize with conduction electrons. The exchange interaction in the d shell maximizes the impurity spin. We study the valence of the Mn impurity as a function of the splitting of the e g to t 2g orbitals in zero magnetic field and for the totally spin-polarized state. The lifting of the degeneracy of the e g levels due to a small quadrupolar field, related to the Mn-O bond length or a Jahn-Teller effect, is also investigated. Possible implications on the magnetoresistance are discussed. copyright 1997 The American Physical Society

Quasi-reference electrodes in confined electrochemical cells can result in in situ production of metallic nanoparticles.

Science.gov (United States)

Perera, Rukshan T; Rosenstein, Jacob K

2018-01-31

Nanoscale working electrodes and miniaturized electroanalytical devices are valuable platforms to probe molecular phenomena and perform chemical analyses. However, the inherent close distance of metallic electrodes integrated into a small volume of electrolyte can complicate classical electroanalytical techniques. In this study, we use a scanning nanopipette contact probe as a model miniaturized electrochemical cell to demonstrate measurable side effects of the reaction occurring at a quasi-reference electrode. We provide evidence for in situ generation of nanoparticles in the absence of any electroactive species and we critically analyze the origin, nucleation, dissolution and dynamic behavior of these nanoparticles as they appear at the working electrode. It is crucial to recognize the implications of using quasi-reference electrodes in confined electrochemical cells, in order to accurately interpret the results of nanoscale electrochemical experiments.

Safety profile of the 9-valent HPV vaccine

DEFF Research Database (Denmark)

Moreira, Edson D; Block, Stan L; Ferris, Daron G

2016-01-01

OBJECTIVES: The overall safety profile of the 9-valent human papillomavirus (9vHPV) vaccine was evaluated across 7 Phase III studies, conducted in males and females (nonpregnant at entry), 9 to 26 years of age. METHODS: Vaccination was administered as a 3-dose regimen at day 1, and months 2 and 6....... More than 15 000 subjects received ≥1 dose of 9vHPV vaccine. In 2 of the studies, >7000 control subjects received ≥1 dose of quadrivalent HPV (qHPV) vaccine. Serious and nonserious adverse events (AEs) and new medical conditions were recorded throughout the study. Subjects testing positive...... for pregnancy at day 1 were not vaccinated; those who became pregnant after day 1 were discontinued from further vaccination until resolution of the pregnancy. Pregnancies detected after study start (n = 2950) were followed to outcome. RESULTS: The most common AEs (≥5%) experienced by 9vHPV vaccine recipients...

Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials.

Science.gov (United States)

Sun, Zhiming; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L; Xi, Yunfei

2013-12-15

A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent iron composite materials have potential applications in environmental remediation. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparing different commercial zero valent iron nanoparticles to immobilize As and Hg in brownfield soil.

Science.gov (United States)

Gil-Díaz, M; Alonso, J; Rodríguez-Valdés, E; Gallego, J R; Lobo, M C

2017-04-15

Nanoscale zero valent iron (nZVI) particles obtained by different methods differ in their structure, which lead to different reactivity, and therefore a likely difference in the remediation efficiency. The present study compares the effectiveness of three commercial ZVI nanoparticles to immobilize As and Hg in two soils (A and B) collected from a brownfield highly contaminated by mining and metallurgy activities. Scarce data are available on the effectiveness of nZVI for Hg immobilization in soil. Two commercial nZVI slurries from Toda (RNIP and RNIP-D) and one from Nano Iron (25S) were used at different doses (1, 5 and 10%). The metal(loid) availability and mobility was evaluated with the TCLP test and Tessier extraction procedure. The influence of nZVI application on As and Hg speciation was also evaluated as well as its impact on soil pH, electrical conductivity and soil phytotoxicity to vetch germination. The three commercial nZVI particles significantly reduced As and Hg availability in the two soils studied, which led to a decrease in soil phytotoxicity. At the dose of 5% of nZVI a decrease of exchangeable-As higher than 70% was observed for both soils, whereas in the case of Hg, a higher dose of nZVI (10%) was necessary to achieve reductions of exchangeable-Hg between 63 and 90% depending on the type of nZVI and soil. No impact on soil pH and electrical conductivity was observed. The effectiveness of metal(loid) immobilization depended on type of nZVI, soil properties and metal(loid) characteristics. Nanoparticles from Nano Iron showed better results for As immobilization whereas RNIP nanoparticles were more effective for Hg. Overall, 25S at the dose of 5% resulted more effective than RNIP nanoparticles for the reduction of exchangeable-As (in the range of 6-14%), whereas RNIP and RNIP-D were 10 and 13% more effective, respectively, for the reduction of exchangeable-Hg at the dose of 10% in soil B. Thus, nZVI can be used for the remediation of highly As and

Biosorbents for Removing Hazardous Metals and Metalloids †

Science.gov (United States)

Inoue, Katsutoshi; Parajuli, Durga; Ghimire, Kedar Nath; Biswas, Biplob Kumar; Kawakita, Hidetaka; Oshima, Tatsuya; Ohto, Keisuke

2017-01-01

Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II), Cr(VI), Sb(III and V), and As(III and V) were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II). Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide) into biosorbents that effectively removed Pb(II). These materials also effectively removed Sb(III and V) and As(III and V) when these were preloaded with multi-valent metal ions such as Zr(IV) and Fe(III). Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI), were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid. PMID:28773217

Remediation of Chlorpyrifos-Contaminated Soils by Laboratory-Synthesized Zero-Valent Nano Iron Particles: Effect of pH and Aluminium Salts

Directory of Open Access Journals (Sweden)

A. Vijaya Bhaskar Reddy

2013-01-01

Full Text Available Degradation of the insecticide chlorpyrifos in contaminated soils was investigated using laboratory synthesized zero-valent nano iron (ZVNI particles. The synthesized ZVNI particles were characterized as nanoscale sized by scanning electron microscopy (SEM and transmission electron microscopy (TEM. The zero-valent state (Fe0 of iron was confirmed by EDAX analysis and the morphology of the ZVNI particles was studied by XRD. Batch experiments were conducted by treating the chlorpyrifos contaminated soil with ZVNI, our results indicate that 90% of chlorpyrifos was degraded after 10 days of incubation. Only 32% degradation was observed with micro zero-valent iron (mZVI and no considerable degradation was attained without ZVNI. The degradation of chlorpyrifos followed the first-order kinetics with a rate constant and a half-life of 0.245 day−1 and 2.82 days, respectively. Degradation was monitored at two different pH values, that is, pH 10 and pH 4. Chlorpyrifos degradation rate constant increased as the pH decreases from 10 to 4. The corresponding rate constant and half-lives were 0.43 day−1 and 1.57days for pH 4, 0.18 day−1 and 3.65 days for pH 10. In addition, an attempt was made by augmenting Al2(SO43 with ZVNI and it was found that the degradation rate of chlorpyrifos was greatly enhanced and the rate constant was rapidly increased from 0.245 day−1 to 0.60 day−1. Hydrolysis and stepwise dechlorination pathway of chlorpyrifos with ZVNI was the dominant reaction.

Treatment with belimumab in systemic lupus erythematosus does not impair antibody response to 13-valent pneumococcal conjugate vaccine.

Science.gov (United States)

Nagel, J; Saxne, T; Geborek, P; Bengtsson, A A; Jacobsen, S; Svaerke Joergensen, C; Nilsson, J-Å; Skattum, L; Jönsen, A; Kapetanovic, M C

2017-09-01

Background/purpose The objective of this study was to explore the impact of systemic lupus erythematosus and belimumab given in addition to standard of care therapy on 13-valent conjugated pneumococcal vaccine (PCV13) response. Methods Forty-seven systemic lupus erythematosus patients and 21 healthy controls were immunized with a single dose of 13-valent conjugated pneumococcal vaccine. Forty systemic lupus erythematosus patients were treated with traditional disease-modifying anti rheumatic drugs, 11 of those received belimumab in addition, and 32 patients were treated with concomitant prednisolone. Quantification of serotype specific IgG levels to 12 pneumococcal capsular polysaccharides was performed in serum taken before and four to six weeks after vaccination using multiplex fluorescent microsphere immunoassay. IgG levels against serotypes 23F and 6B were also analyzed using standard enzyme-linked immunosorbent assays. Opsonophagocytic assay was performed on serotype 23F to evaluate the functionality of the antibodies. Pre- and post-vaccination log transformed antibody levels were compared to determine the impact of systemic lupus erythematosus diagnosis and different treatments on antibody response. Results Systemic lupus erythematosus patients as a group showed lower post-vaccination antibody levels and lower fold increase of antibody levels after vaccination compared to controls ( p = 0.02 and p = 0.009, respectively). Systemic lupus erythematosus patients treated with belimumab in addition to standard of care therapy or with only hydroxychloroquine did not differ compared to controls, whereas the other treatment groups had significantly lower fold increase of post-vaccination antibody levels. Higher age was associated with lower post-vaccination antibody levels among systemic lupus erythematosus patients. Conclusion Belimumab given in addition to traditional disease-modifying anti rheumatic drugs or prednisolone did not further impair antibody

Expanding Thorium Hydride Chemistry Through Th²⁺, Including the Synthesis of a Mixed-Valent Th⁴⁺/Th³⁺ Hydride Complex.

Science.gov (United States)

Langeslay, Ryan R; Fieser, Megan E; Ziller, Joseph W; Furche, Filipp; Evans, William J

2016-03-30

The reactivity of the recently discovered Th(2+) complex [K(18-crown-6)(THF)2][Cp″3Th], 1 [Cp'' = C5H3(SiMe3)2-1,3], with hydrogen reagents has been investigated and found to provide syntheses of new classes of thorium hydride compounds. Complex 1 reacts with [Et3NH][BPh4] to form the terminal Th(4+) hydride complex Cp″3ThH, 2, a reaction that formally involves a net two-electron reduction. Complex 1 also reacts in the solid state and in solution with H2 to form a mixed-valent bimetallic product, [K(18-crown-6)(Et2O)][Cp″2ThH2]2, 3, which was analyzed by X-ray crystallography, electron paramagnetic resonance and optical spectroscopy, and density functional theory. The existence of 3, which formally contains Th(3+) and Th(4+), suggested that KC8 could reduce [(C5Me5)2ThH2]2. In the presence of 18-crown-6, this reaction forms an analogous mixed-valent product formulated as [K(18-crown-6)(THF)][(C5Me5)2ThH2]2, 4. A similar complex with (C5Me4H)(1-) ligands was not obtained, but reaction of (C5Me4H)3Th with H2 in the presence of KC8 and 2.2.2-cryptand at -45 °C produced two monometallic hydride products, namely, (C5Me4H)3ThH, 5, and [K(2.2.2-cryptand)]{(C5Me4H)2[η(1):η(5)-C5Me3H(CH2)]ThH]}, 6. Complex 6 contains a metalated tetramethylcyclopentadienyl dianion, [C5Me3H(CH2)](2-), that binds in a tuck-in mode.

Oprensning af forureningen på depotet ved Høfde 42 ved hjælp af nul-valent jern

DEFF Research Database (Denmark)

Fjordbøge, Annika Sidelmann; Kjeldsen, Peter; Petersen, Peter Alfred

Rapporten beskriver forsøg med nul-valent jern på forurenet vand og sediment fra depotet ved Høfde 42 på Harboøre Tange. Resultaterner viser, at parathion og malathion hurtigt og fuldstændigt bliver omdannet til langt mindre toksiske forbindelser, og endvidere nedbrydes mange af de tilstedeværende...

Ecoturismo y desarrollo comunitario: el caso de “Valentín Natural” en el sureste de México

Directory of Open Access Journals (Sweden)

Ricardo Isaac Márquez

2016-06-01

Full Text Available Se presenta el estudio de caso de “Valentín Natural”, promocionado por el Gobierno mexicano como un proyecto exitoso de ecoturismo comunitario en el sureste de México. Desde la perspectiva de los pobladores locales, se describe la manera como el ecoturismo ha modificado sus condiciones de vida, particularmente como fuente de empleo y de ingresos para la población. Los resultados indican que más allá de la retórica oficial, “Valentín Natural” no puede considerarse como un caso de éxito. La actividad ecoturística no ha sido fuente de empleos ni de ingresos para la población, su participación ha sido limitada y sectores importantes han sido excluidos del proceso de toma de decisiones. Se concluye que se requieren políticas públicas coherentes de largo plazo que fortalezcan las capacidades locales y faciliten los recursos necesarios para consolidar los proyectos ecoturísticos de las comunidades rurales en un marco de sustentabilidad.

Effect of magnetic field on the zero valent iron induced oxidation reaction

International Nuclear Information System (INIS)

Kim, Dong-hyo; Kim, Jungwon; Choi, Wonyong

2011-01-01

Highlights: → We investigate the zero valent iron induced oxidation in the presence of magnetic field. → The oxidative degradation of 4-chlorophenol is enhanced by the magnetic field. → ESR measurement confirms that more OH radicals are generated in the presence of magnetic field. → The magnetic field affects the mass transfer of O 2 and the recombination of radicals. - Abstract: The magnetic field (MF) effect on the zero valent iron (ZVI) induced oxidative reaction was investigated for the first time. The degradation of 4-chlorophenol (4-CP) in the ZVI system was employed as the test oxidative reaction. MF markedly enhanced the degradation of 4-CP with the concurrent production of chlorides. The consumption of dissolved O 2 by ZVI reaction was also enhanced in the presence of MF whereas the competing reaction of H 2 production from proton reduction was retarded. Since the ZVI-induced oxidation is mainly driven by the in situ generated hydroxyl radicals, the production of OH radicals was monitored by the spin trap method using electron spin resonance (ESR) spectroscopy. It was confirmed that the concentration of trapped OH radicals was enhanced in the presence of MF. Since both O 2 and Fe 0 are paramagnetic, the diffusion of O 2 onto the iron surface might be accelerated under MF. The magnetized iron can attract oxygen on itself, which makes the mass transfer process faster. As a result, the surface electrochemical reaction between Fe 0 and O 2 can be accelerated with the enhanced production of OH radicals. MF might retard the recombination of OH radicals as well.

A Study of Efficiency of Zero-valent Iron Nanoparticles in Degradation of Trichlorethylene from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Samaneh Dehghan

2016-12-01

mg/l, and contact time= 86 min. The results of kinetic studies revealed that TCE degradation by nZVI follows first-order kinetic model. Conclusion: It is conclude that zero-valent iron nanoparticles have a good efficiency in the degradation of TCE. On the other hand, separation of these nanoparticles is simple due to its magnetism properties, which can improve the use of these nanoparticles. 

Kinetic and mechanistic studies of reactive intermediates in photochemical and transition metal-assisted oxidation, decarboxylation and alkyl transfer reactions

Energy Technology Data Exchange (ETDEWEB)

Carraher, Jack McCaslin [Iowa State Univ., Ames, IA (United States)

2014-01-01

Reactive species like high-valent metal-oxo complexes and carbon and oxygen centered radicals are important intermediates in enzymatic systems, atmospheric chemistry, and industrial processes. Understanding the pathways by which these intermediates form, their relative reactivity, and their fate after reactions is of the utmost importance. Herein are described the mechanistic detail for the generation of several reactive intermediates, synthesis of precursors, characterization of precursors, and methods to direct the chemistry to more desirable outcomes yielding ‘greener’ sources of commodity chemicals and fuels.

Differential B-cell memory around the 11-month booster in children vaccinated with a 10- or 13-valent pneumococcal conjugate vaccine

NARCIS (Netherlands)

van Westen, Els; Wijmenga-Monsuur, Alienke J; van Dijken, Harry H; van Gaans-van den Brink, Jacqueline A M; Kuipers, Betsy; Knol, Mirjam J; Berbers, Guy A M; Sanders, Elisabeth A M; Rots, Nynke Y; van Els, Cécile A C M

2015-01-01

BACKGROUND: Both the 10- and 13-valent pneumococcal conjugate vaccines (PCV10 and PCV13) induce immunological memory against Streptococcus pneumoniae infections caused by vaccine serotypes. In addition to comparing serum antibody levels, we investigated frequencies of serotype-specific plasma cells

Kondo resonance in the neutron spectra of intermediate-valent YbAl3

International Nuclear Information System (INIS)

Walter, U.; Holland-Moritz, E.; Fisk, Z.

1991-01-01

We have measured the dynamic susceptibility of intermediate-valent YbAl 3 by means of cold-neutron scattering. We find two intense magnetic excitations below 40 meV. One of these, with location around 18 meV at helium temperatures, shifts steadily toward 0 meV with increasing temperatures. While crystal field interactions are unable to account for such a behavior, this excitation is in good agreement with a transition from the f ground state to a Kondo resonance as described by the Anderson model. In particular, it definitely excludes a gaplike magnetic response with gap width Δ=30 meV as asserted earlier

Poetry and Community in the Work of José Ángel Valente

Directory of Open Access Journals (Sweden)

Manus O'Dwyer

2017-06-01

Full Text Available This article examines the work of Spanish poet José Ángel Valente (1929-2000 in terms of his exploration of the relation between the poet, poetic language, and community. In it I discuss the tension in Valente’s work between a desire to create a language that would be foundational of community and the ethical commitment to alterity. I argue that the poetry of the second half of Valente’s career, which has been considered hermetic, or even solipsistic, can be read in terms of a contemporary philosophical discourse that seeks to think community in terms that are not exclusive of alterity.

Ultrasound-assisted activation of zero-valent magnesium for nitrate denitrification: identification of reaction by-products and pathways.

Science.gov (United States)

Ileri, Burcu; Ayyildiz, Onder; Apaydin, Omer

2015-07-15

Zero-valent magnesium (Mg(0)) was activated by ultrasound (US) in an aim to promote its potential use in water treatment without pH control. In this context, nitrate reduction was studied at batch conditions using various doses of magnesium powder and ultrasound power. While neither ultrasound nor zero-valent magnesium alone was effective for reducing nitrate in water, their combination removed up to 90% of 50 mg/L NO3-N within 60 min. The rate of nitrate reduction by US/Mg(0) enhanced with increasing ultrasonic power and magnesium dose. Nitrogen gas (N2) and nitrite (NO2(-)) were detected as the major reduction by-products, while magnesium hydroxide Mg(OH)2 and hydroxide ions (OH(-)) were identified as the main oxidation products. The results from SEM-EDS measurements revealed that the surface oxide level decreased significantly when the samples of Mg(0) particles were exposed to ultrasonic treatment. The surface passivation of magnesium particles was successfully minimized by mechanical forces of ultrasound, which in turn paved the way to sustain the catalyst activity toward nitrate reduction. Copyright © 2015 Elsevier B.V. All rights reserved.

High-valent iron (Fe(VI), Fe(V), and Fe(IV)) species in water: characterization and oxidative transformation of estrogenic hormones

Czech Academy of Sciences Publication Activity Database

Machalová-Šišková, K.; Jančula, Daniel; Drahoš, B.; Machala, L.; Babica, Pavel; Godoy Alonso, Paula; Trávníček, Z.; Tuček, J.; Maršálek, Blahoslav; Sharma, V. K.; Zbořil, R.

2016-01-01

Roč. 18, č. 28 (2016), s. 18802-18810 ISSN 1463-9076 R&D Projects: GA MPO FR-TI3/196 Institutional support: RVO:67985939 Keywords : high-valent iron species * estrogenic hormones * oxidative transformation Subject RIV: DJ - Water Pollution ; Quality Impact factor: 4.123, year: 2016

Monothioarsenate Occurrence in Bangladesh Groundwater and Its Removal by Ferrous and Zero-Valent Iron Technologies.

Science.gov (United States)

Planer-Friedrich, Britta; Schaller, Jörg; Wismeth, Fabian; Mehlhorn, Judith; Hug, Stephan J

2018-05-15

In most natural groundwaters, sulfide concentrations are low, and little attention has been paid to potential occurrence of thioarsenates (As V S n -II O 4- n 3- with n = 1-4). Thioarsenate occurrence in groundwater could be critical with regard to the efficiency of iron (Fe)-based treatment technologies because previous studies reported less sorption of thioarsenates to preformed Fe-minerals compared to arsenite and arsenate. We analyzed 273 groundwater samples taken from different wells in Bangladesh over 1 year and detected monothioarsenate (MTA), likely formed via solid-phase zero-valent sulfur, in almost 50% of all samples. Concentrations ranged up to >30 μg L -1 (21% of total As). MTA removal by locally used technologies in which zero-valent or ferrous Fe is oxidized by aeration and As sorbs or coprecipitates with the forming Fe(III)hydroxides was indeed lower than for arsenate. The presence of phosphate required up to three times as much Fe(II) for comparable MTA removal. However, in contrast to previous sorption studies on preformed Fe minerals, MTA removal, even in the presence of phosphate, was still higher than that of arsenite. The more efficient MTA removal is likely caused by a combination of coprecipitation and adsorption rendering the tested Fe-based treatment technologies suitable for As removal also in the presence of MTA.

M-edge x-ray absorption spectroscopy: A new tool for dilute mixed-valent materials

International Nuclear Information System (INIS)

Kaindl, G.; Brewer, W.D.; Kalkowski, G.; Holtzberg, F.

1983-01-01

The valence of Tm compounds is derived from M/sub V/ x-ray absorption spectra recorded by total electron yield under ultra-high-vacuum conditions. For mixed-valent systems the spectra are superpositions of Tm 3+ (three lines) and Tm 2+ (one line) components, providing accurate mean valence values even in highly dilute systems, such as Tm/sub x/Y/sub 1-x/Se, which agree well with those from lattice constant systematics. A surface valence change on TmS(100) is identified as an initial-state effect

Reductive Degradation of Perfluorinated Compounds in Water using Mg-aminoclay coated Nanoscale Zero Valent Iron

OpenAIRE

Arvaniti, Olga S.; Hwang, Yuhoon; Andersen, Henrik Rasmus; Stasinakis, Athanasios S.; Thomaidis , Nikolaos S.; Aloupi, Maria

2015-01-01

Perfluorinated Compounds (PFCs) are extremely persistent micropollutants that are detected worldwide. We studied the removal of PFCs (perfluorooctanoic acid; PFOA, perfluorononanoic acid; PFNA, perfluorodecanoic acid; PFDA and perfluorooctane sulfonate; PFOS) from water by different types of nanoscale zero-valent iron (nZVI). Batch experiments showed that an iron dose of 1 g•L-1 in the form of Mg-aminoclay (MgAC) coated nZVI, at an initial pH of 3.0 effectively removed 38 % to 96 % of individ...

Progress and prospect of adsorptive removal of heavy metal ions from aqueous solution using metal-organic frameworks: A review of studies from the last decade.

Science.gov (United States)

Wen, Jia; Fang, Ying; Zeng, Guangming

2018-06-01

The efficient removal of heavy metals (HMs) from the environment has become an important issue from both biological and environmental perspectives. Recently, porous metal-organic frameworks (MOFs), combining central metals and organic ligands, have been proposed as promising materials in the capture of various toxic substances, including HMs, due to their unique characteristics. Here we review recent progress in the field of water remediation from the perspective of primary HMs (including divalent metals and variable-valent metals) in water pollution and the corresponding MOFs (including virgin and modified MOFs, magnetic MOFs composites and so on) that can remove these metals from water. The reported values of various MOFs for adsorption of heavy metal ions were 8.40-313 mg Pb(II) g -1 , 0.65-2173 mg Hg(II) g -1 , 3.63-145 mg Cd(II) g -1 , 14.0-127 mg Cr(III) g -1 , 15.4-145 mg Cr(VI) g -1 , 49.5-123 mg As(III) g -1 , and 12.3-303 mg As(V) g -1 . The main adsorption mechanisms associated with these processes are chemical (including coordination interaction, chemical bonding and acid-base interactions) and physical (including electrostatic interaction, diffusion and van der Waals force) adsorption, which were discussed in detailed. Further efforts should be made towards expanding the repertoire of MOFs that effectively remove multiple targeted HMs, as well as exploring possible applications of MOFs in the removal of HMs from non-aqueous environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biological reference materials and analysis of toxic elements

Energy Technology Data Exchange (ETDEWEB)

Subramanian, R; Sukumar, A

1988-12-01

Biological monitoring of toxic metal pollution in the environment requires quality control analysis with use of standard reference materials. A variety of biological tissues are increasingly used for analysis of element bioaccumulation, but the available Certified Reference Materials (CRMs) are insufficient. An attempt is made to review the studies made using biological reference materials for animal and human tissues. The need to have inter-laboratory studies and CRM in the field of biological monitoring of toxic metals is also discussed.

Kinetics of nitrate adsorption and reduction by nano-scale zero valent iron (NZVI): Effect of ionic strength and initial pH

DEFF Research Database (Denmark)

Kim, Do-Gun; Hwang, Yuhoon; Shin, Hang-Sik

2016-01-01

Kinetic models for pollutants reduction by Nano-scale Zero Valent Iron (NZVI) were tested in this study to gain a better understanding and description of the reaction. Adsorption kinetic models and a heterogeneous catalytic reaction kinetic equation were proposed for nitrate removal and for ammon...

Fundamental Studies of the Removal of Contaminants from Ground and Waste Waters via Reduction by Zero-Valent Metals

International Nuclear Information System (INIS)

Yarmoff, Jory A.; Amrhein, Christopher

1999-01-01

Contaminated groundwater and surface waters are a problem throughout the United States and the world. In many instances, the types of contamination can be directly attributed to man's actions. For instance, the burial of chemical wastes, casual disposal of solvents in unlined pits, and the development of irrigated agriculture have all contributed to groundwater and surface water contamination. The kinds of contaminants include chlorinated solvents and toxic trace elements (including radioisotopes) that are soluble and mobile in soils and aquifers. Oxyanions of uranium, selenium, chromium, arsenic, technetium, and chlorine (as perchlorate) are frequently found as contaminants on many DOE sites. Uranium is a particularly widespread contaminant at most DOE sites including Oak Ridge, Rocky Flats, Hanford, Idaho (INEEL), and Fernald. The uranium contamination is associated with mining and milling of uranium ore (UMTRA sites), isotope separation and enrichment, and mixed waste and TRU waste burial. In addition, the careless disposal of halogenated solvents, such as carbon tetrachloride and trichloroethylene, has further contaminated many groundwaters at these sites. A potential remediation method for many of these oxyanions and chlorinated-solvents is to react the contaminated water with zero-valent iron. In this reaction, the iron serves as both an electron source and as a catalyst. Elemental iron is already being used on an experimental basis at many DOE sites. Both in situ reactive barriers and above-ground reactors are being developed for this purpose. However, the design and operation of these treatment systems requires a detailed process-level understanding of the interactions between the contaminants and the iron surfaces. We are performing fundamental investigations of the interactions of the relevant chlorinated solvents and trace element-containing compounds with single- and poly-crystalline Fe surfaces. The aim of this work is to develop th e fundamental

Acute toxicity of metals and reference toxicants to a freshwater ostracod, Cypris subglobosa Sowerby, 1840 and correlation to EC50 values of other test models

International Nuclear Information System (INIS)

Khangarot, B.S.; Das, Sangita

2009-01-01

The ostracod Cypris subglobosa Sowerby, 1840 static bioassay test on the basis of a 48 h of 50% of immobilization (EC 50 ) has been used to measure the toxicity of 36 metals and metalloids and 12 reference toxicants. Among the 36 metals and metalloids, osmium (Os) was found to be the most toxic in the test while boron (B), the least toxic. The EC 50 values of this study revealed positive linear relationship with the established test models of cladoceran (Daphnia magna), sludge worm (Tubifex tubifex), chironomid larvae (Chironomus tentans), protozoan (Tetrahymena pyriformis), fathead minnow (Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and aquatic macrophyte duckweed (Lemna minor). Correlation coefficients (r 2 ) for 17 physicochemical properties of metals or metal ions and EC 50 s (as pM) were examined by linear regression analysis. The electronegativity, ionization potential, melting point, solubility product of metal sulfides (pK sp ), softness parameter and some other physicochemical characteristics were significantly correlated with EC 50 s of metals to C. subglobosa. The reproducibility of toxicity test was determined using 12 reference toxicants. The coefficient of variability of the EC 50 s ranged from 6.95% to 55.37% and variability was comparable to that noticed for D. magna and other aquatic test models. The study demonstrated the need to include crustacean ostracods in a battery of biotests to detect the presence of hazardous chemicals in soils, sewage sludges, sediments and aquatic systems.

Baseline reference range for trace metal concentrations in whole blood of wild and managed West Indian Manatees (Trichechus manatus) in Florida and Belize

Science.gov (United States)

Takeuchi, Noel Y.; Walsh, Michael T; Bonde, Robert K.; Powell, James A.; Bass, Dean A.; Gaspard, Joseph C.; Barber, David S.

2016-01-01

The West Indian manatee (Trichechus manatus) is exposed to a number of anthropogenic influences, including metals, as they inhabit shallow waters with close proximity to shore. While maintaining homeostasis of many metals is crucial for health, there is currently no baseline reference range that can be used to make clinical and environmental decisions for this endangered species. In this study, whole blood samples from 151 manatees were collected during health assessments performed in Florida and Belize from 2008 through 2011. Whole blood samples (n = 37) from managed care facilities in Florida and Belize from 2009 through 2011 were also used in this study. The concentrations of 17 metals in whole blood were determined, and the data were used to derive a baseline reference range. Impacts of capture location, age, and sex on whole blood metal concentrations were examined. Location and age were related to copper concentrations as values were significantly higher in habitats near urban areas and in calves. Copper may also be a husbandry concern as concentrations were significantly higher in managed manatees (1.17 ± 0.04 ppm) than wild manatees (0.73 ± 0.02 ppm). Zinc (11.20 ± 0.30 ppm) was of special interest as normal concentrations were two to five times higher than other marine mammal species. Arsenic concentrations were higher in Belize (0.43 ± 0.07 ppm), with Placencia Lagoon having twice the concentration of Belize City and Southern Lagoon. Selenium concentrations were lower (0.18 ± 0.09 ppm) than in other marine mammal species. The lowest selenium concentrations were observed in rehabilitating and managed manatees which may warrant additional monitoring in managed care facilities. The established preliminary baseline reference range can be used by clinicians, biologists, and managers to monitor the health of West Indian manatees.

Advantages of low pH and limited oxygenation in arsenite removal from water by zero-valent iron.

Science.gov (United States)

Klas, Sivan; Kirk, Donald W

2013-05-15

The removal of toxic arsenic species from contaminated waters by zero-valent iron (ZVI) has drawn considerable attention in recent years. In this approach, arsenic ions are mainly removed by adsorption to the iron corrosion products. Reduction to zero-valent arsenic on the ZVI surface is possible in the absence of competing oxidants and can reduce arsenic mobility and sludge formation. However, associated removal rates are relatively low. In the current study, simultaneous high reduction and removal rates of arsenite (H3AsO3), the more toxic and mobile environmentally occurring arsenic species, was demonstrated by reacting it with ZVI under limited aeration and relatively low pH. 90% of the removed arsenic was attached to the ZVI particles and 60% of which was in the elemental state. Under the same non-acidic conditions, only 40-60% of the removed arsenic was attached to the ZVI with no change in arsenic oxidation state. Under anaerobic conditions, reduction occurred but total arsenic removal rate was significantly lower and ZVI demand was higher. The effective arsenite removal under acidic oxygen-limited conditions was explained by formation of Fe(II)-solid intermediate on the ZVI surface that provided high surface area and reducing power. Copyright © 2013 Elsevier B.V. All rights reserved.

Influence of the complexones on the ionic transfer through cell membranes and the level of radionuclides-metals accumulation in water plants

International Nuclear Information System (INIS)

Marchiulioniene, D.P.; Motiejuniene, Eh.B.; Zemkajiene, R.R.

1987-01-01

The influence of the complexones diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA) and hydroxyethylidenediphosphonic acid (HEDP) with relatively low concentrations (from 0.1 to 50 mg/l) on ionic permeability of cell membranes of Nitellopsis obtusa algae, as well as on the accumulation levels of the radionuclides 144 Ce, 106 Ru, 90 Sr and 137 Cs in different species of water plants has been studied. It has been shown that complexones under study (with the concentrations up to 50 mg/l) may reduce accumulation levels of three- and four-valent metals and their radionuclides in water plants. For the plants in natural as well as in artificial nutrient medium, however, the complexones increase the availability of metals, forming with the readibly soluble, mobile complex compounds

Removal of Perfluorinated Compounds From Water using Nanoscale Zero-Valent Iron

DEFF Research Database (Denmark)

Arvaniti, Olga S.; Hwang, Yuhoon; Andersen, Henrik Rasmus

Perfluorinated Compounds (PFCs) are persistent micropollutants that have been detected in various environmental and biological matrices, worldwide. During the last decade, these compounds have also been detected in municipal wastewater and tap water. Due to the stability of C-F bond......, the application of biological and conventional physicochemical treatment methods does not seem to remove sufficient these compounds from water and wastewater. In the current study, the removal efficiency of four PFCs using three different types of nanoscale zero-valent iron (nZVI) was investigated. Influencing...... factors such as, initial pH solution, reaction temperature and nZVI dosage were also studied. According to the results, target compounds were removed in the presence of chemically synthesized nZVI modified with Mg-aminoclay (MgAC) than under commercial iron powder and chemically synthesized uncoated n...

ASTM reference radiologic digital image standards

International Nuclear Information System (INIS)

Wysnewski, R.; Wysnewski, D.

1996-01-01

ASTM Reference Radiographs have been essential in defining industry's material defect grade levels for many years. ASTM Reference Radiographs are used extensively as even the American Society for Metals Nondestructive Inspection and Quality Control Metals Handbook, Volume 11, eighth edition refers to ASTM Standard Reference Radiographs. The recently published E 1648 Standard Reference Radiographs for Examination of Aluminum Fusion Welds is a prime example of the on-going need for these references. To date, 14 Standard Reference Radiographs have been published to characterize material defects. Standard Reference Radiographs do not adequately address film-less radiologic methods. There are differences in mediums to content with. On a computer CRT defect indications appear differently when compared to indications viewed in a radiograph on a view box. Industry that uses non-film radiologic methods of inspection can be burdened with additional time and money developing internal standard reference radiologic images. These references may be deemed necessary for grading levels of product defects. Because there are no ASTM Standard Reference Radiologic data files for addressing this need in the industry, the authors of this paper suggested implementing a method for their creation under ASTM supervision. ASTM can assure continuity to those users making the transition from analog radiographic images to digital image data by swiftly addressing the requirements for reference digital image standards. The current status and possible future activities regarding a method to create digital data files is presented in this paper summary

Recovery of high-purity metallic Pd from Pd(II)-sorbed biosorbents by incineration.

Science.gov (United States)

Won, Sung Wook; Lim, Areum; Yun, Yeoung-Sang

2013-06-01

This work reports a direct way to recover metallic palladium with high purity from Pd(II)-sorbed polyethylenimine-modified Corynebacterium glutamicum biosorbent using a combined method of biosorption and incineration. This study is focused on the incineration part which affects the purity of recovered Pd. The incineration temperature and the amount of Pd loaded on the biosorbent were considered as major factors in the incineration process, and their effects were examined. The results showed that both factors significantly affected the enhancement of the recovery efficiency and purity of the recovered Pd. SEM-EDX and XRD analyses were used to confirm that Pd phase existed in the ash. As a result, the recovered Pd was changed from PdO to zero-valent Pd as the incineration temperature was increased from 600 to 900°C. Almost 100% pure metallic Pd was recovered with recovery efficiency above 99.0% under the conditions of 900°C and 136.9 mg/g. Copyright © 2013 Elsevier Ltd. All rights reserved.

Graduated characterization method using a multi-well microplate for reducing reactivity of nanoscale zero valent iron materials

DEFF Research Database (Denmark)

Hwang, Yuhoon; Salatas, Apostolos; Mines, Paul D.

2015-01-01

Even though nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of n...... with different compounds, combined with the use of a multi-well microplate based color assay, promises to be a useful and simple tool in various nZVI related research topics....

Emerging pneumococcal carriage serotypes in a high-risk population receiving universal 7-valent pneumococcal conjugate vaccine and 23-valent polysaccharide vaccine since 2001

Directory of Open Access Journals (Sweden)

Stubbs Liz

2009-08-01

Full Text Available Abstract Background In Australia in June 2001, a unique pneumococcal vaccine schedule commenced for Indigenous infants; seven-valent pneumococcal conjugate vaccine (7PCV given at 2, 4, and 6 months of age and 23-valent pneumococcal polysaccharide vaccine (23PPV at 18 months of age. This study presents carriage serotypes following this schedule. Methods We conducted cross sectional surveys of pneumococcal carriage in Aboriginal children 0 to 6 years of age living in remote Aboriginal communities (RACs in 2003 and 2005. Nasal secretions were collected and processed according to published methods. Results 902 children (mean age 25 months living in 29 communities in 2003 and 818 children (mean age 35 months in 17 communities in 2005 were enrolled. 87% children in 2003 and 96% in 2005 had received two or more doses of 7PCV. From 2003 to 2005, pneumococcal carriage was reduced from 82% to 76% and reductions were apparent in all age groups; 7PCV-type carriage was reduced from 11% to 8%, and 23PPV-non-7PCV-type carriage from 31% to 25% respectively. Thus non-23PPV-type carriage increased from 57% to 67%. All these changes were statistically significant, as were changes for some specific serotypes. Shifts could not be attributed to vaccination alone. The top 10 of 40 serotypes identified were (in descending order 16F, 19A, 11A, 6C, 23B, 19F, 6A, 35B, 6B, 10A and 35B. Carriage of penicillin non-susceptible (MIC > = 0.12 μg/mL strains (15% overall was detected in serotypes (descending order 19A, 19F, 6B, 16F, 11A, 9V, 23B, and in 4 additional serotypes. Carriage of azithromycin resistant (MIC > = 2 μg/mL strains (5% overall, was detected in serotypes (descending order 23B, 17F, 9N, 6B, 6A, 11A, 23F, and in 10 additional serotypes including 6C. Conclusion Pneumococcal carriage remains high (~80% in this vaccinated population. Uptake of both pneumococcal vaccines increased, and carriage was reduced between 2003 and 2005. Predominant serotypes in combined

Fluidized bed bioreactors coupled to zero-valent iron filters for removal of high concentrations of perchloroethylene

International Nuclear Information System (INIS)

Poggi-Varaldo, H. M.; Herrera-Lopez, D.; Garcia-Mena, J.; Rios-Leal, E.

2009-01-01

The aim of this work was to evaluate the effect of coupling continuous bioreactors with zero-valent iron filters on removal of PCE. Two types of reactors with simultaneous electron acceptors were used: partially aerated methanogenic (PAM) and methanogenic-denitrifying (M-D). Lab-scale fluidized-bed reactors (FBBR) were operated as follows: PAM at λ=135 g COD/g O 2 and M-D at λ=9 g COD/g N-NO 3 with 80 mg/L of PCE in the influent. (Author)

Inhibition of Nitrate Reduction by NaCl Adsorption on a Nano-Zero-Valent Iron Surface during a Concentrate Treatment for Water Reuse

DEFF Research Database (Denmark)

Hwang, Yuhoon; Kim, Dogun; Shin, Hang-Sik

2015-01-01

Nanoscale zero-valent iron (NZVI) has been considered as a possible material to treat water and wastewater. However, it is necessary to verify the effect of the matrix components in different types of target water. In this study, different effects depending on the sodium chloride (Na...

Acute toxicity of metals and reference toxicants to a freshwater ostracod, Cypris subglobosa Sowerby, 1840 and correlation to EC{sub 50} values of other test models

Energy Technology Data Exchange (ETDEWEB)

Khangarot, B.S., E-mail: bkhangarot@hotmail.com [Ecotoxicology Division, Indian Institute of Toxicology Research (Formerly: Industrial Toxicology Research Centre), Post Box No. 80, Mahatma Gandhi Marg, Lucknow 226001 (India); Das, Sangita [Ecotoxicology Division, Indian Institute of Toxicology Research (Formerly: Industrial Toxicology Research Centre), Post Box No. 80, Mahatma Gandhi Marg, Lucknow 226001 (India)

2009-12-30

The ostracod Cypris subglobosa Sowerby, 1840 static bioassay test on the basis of a 48 h of 50% of immobilization (EC{sub 50}) has been used to measure the toxicity of 36 metals and metalloids and 12 reference toxicants. Among the 36 metals and metalloids, osmium (Os) was found to be the most toxic in the test while boron (B), the least toxic. The EC{sub 50} values of this study revealed positive linear relationship with the established test models of cladoceran (Daphnia magna), sludge worm (Tubifex tubifex), chironomid larvae (Chironomus tentans), protozoan (Tetrahymena pyriformis), fathead minnow (Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and aquatic macrophyte duckweed (Lemna minor). Correlation coefficients (r{sup 2}) for 17 physicochemical properties of metals or metal ions and EC{sub 50}s (as pM) were examined by linear regression analysis. The electronegativity, ionization potential, melting point, solubility product of metal sulfides (pK{sub sp}), softness parameter and some other physicochemical characteristics were significantly correlated with EC{sub 50}s of metals to C. subglobosa. The reproducibility of toxicity test was determined using 12 reference toxicants. The coefficient of variability of the EC{sub 50}s ranged from 6.95% to 55.37% and variability was comparable to that noticed for D. magna and other aquatic test models. The study demonstrated the need to include crustacean ostracods in a battery of biotests to detect the presence of hazardous chemicals in soils, sewage sludges, sediments and aquatic systems.

Impacts of zero valent iron, natural zeolite and Dnase on the fate of antibiotic resistance genes during thermophilic and mesophilic anaerobic digestion of swine manure.

Science.gov (United States)

Zhang, Junya; Sui, Qianwen; Zhong, Hui; Meng, Xiaoshan; Wang, Ziyue; Wang, Yawei; Wei, Yuansong

2018-06-01

This study investigated the fate of antibiotic resistance genes (ARGs) during mesophilic (mAD) and thermophilic digestion (tAD) of swine manure through zero valent iron (ZVI), natural zeolite and Dnase addition. Changes of microbial community, intI1, heavy metal resistance genes (MRGs) and virulence factors (VFs) were followed to clarify the influencing factors to ARGs reduction. Results showed that AD could realize ARGs reduction with tAD superior to mAD, and ZVI and natural zeolite could further enhance the reduction, especially for natural zeolite addition at mAD. The reduction efficiency of the relative abundance of ARGs was increased by 33.3% and 138.5% after ZVI and natural zeolite addition, respectively, but Dnase deteriorated ARGs reduction at mAD. Most of ARGs could be reduced effectively except sulII and tetM. Network analysis and partial redundancy analysis indicated that co-occurrence of MRGs followed by microbial community contributed the most to the variation of ARGs fate among treatments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Traducción de poesía e intertextualidad en el poemario Apocrypha de Catherynne M. Valente

OpenAIRE

Barba Muñoz, Laura

2017-01-01

Catherynne M. Valente es una autora contemporánea de origen estadounidense cuya escritura, repleta de simbolismo y referencias intertextuales, alcanza su máximo esplendor en Apocrypha [2005]. Este poemario, compuesto por dos partes, contiene poemas y relatos en prosa poética de corte bíblico y mitológico que, condimentados con extranjerismos y culturemas, son de gran interés para los estudios de traducción de poesía e intertextualidad.

A Mononuclear Non-Heme Manganese(IV)-Oxo Complex Binding Redox-Inactive Metal Ions

Energy Technology Data Exchange (ETDEWEB)

Chen, Junying; Lee, Yong-Min; Davis, Katherine M.; Wu, Xiujuan; Seo, Mi Sook; Cho, Kyung-Bin; Yoon, Heejung; Park, Young Jun; Fukuzumi, Shunichi; Pushkar, Yulia N.; Nam, Wonwoo [Ewha; (Purdue); (Osaka)

2013-05-29

Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal–oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)–oxo complex bearing a pentadentate N₅ ligand has been synthesized and used in the synthesis of a Mn(IV)–oxo complex binding scandium ions. The Mn(IV)–oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)–oxo complex are markedly influenced by binding of Sc³⁺ ions in oxidation reactions, such as a ~2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ~180-fold decrease in the rate of C–H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)–oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal–oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.

Definition of a high intensity metal halide discharge reference lamp

NARCIS (Netherlands)

Stoffels, W.W.; Baede, A.H.F.M.; Mullen, van der J.J.A.M.; Haverlag, M.; Zissis, G.

2006-01-01

The design of a ref. metal halide discharge lamp is presented. This lamp is meant as a common study object for researchers working on metal halide discharge lamps, who by using the same design will be able to compare results between research groups, diagnostic techniques and numerical models. The

Ferrous and common nonferrous metals industries and associated scrap metals: a review

International Nuclear Information System (INIS)

Mautz, E.W.

1975-11-01

Literature on the common metals industries, scrap metal relationships, and transportation aspects has been reviewed as background information in a study to determine the feasibility of a portable melting facility for radioactively contaminated metals. This report draws substantially on government-sponsored studies. Aluminum, copper, iron and steel, and nickel metal industries are discussed from the viewpoints of the general industry characteristics, primary metal production processes, and secondary metal processing aspects. 46 references, 10 tables

Choosing between 7-, 10- and 13-valent pneumococcal conjugate vaccines in childhood: a review of economic evaluations (2006-2014).

Science.gov (United States)

Wu, David Bin-Chia; Chaiyakunapruk, Nathorn; Chong, Huey-Yi; Beutels, Philippe

2015-03-30

Seven-valent pneumococcal conjugate vaccines (PCV7) have been used in children for more than a decade. Given the observed increase in disease caused by pneumococcal serotypes not covered by PCV7, an increasing number of countries are switching from 7-valent to 10- and 13-valent PCVs ("PCV10" and "PCV13"). Economic evaluations are important tools to inform decisions and price negotiations to make such a switch. This review aims to provide a critical assessment of economic evaluations involving PCV10 or PCV13, published since 2006. We searched Scopus, ISI Web of Science (SCI and SSCI) and Pubmed to retrieve, select and review relevant studies, which were archived between 1st January 2006 and 31st January 2014. The review protocol involved standard extraction of assumptions, methods, results and sponsorships from the original studies. Sixty-three economic evaluations on PCVs published since January 2006 were identified. About half of these evaluated PCV10 and/or PCV13, the subject of this review. At current prices, both PCV13 and PCV10 were likely judged preferable to PCV7. However, the combined uncertainty related to price differences, burden of disease, vaccine effectiveness, herd and serotype replacement effects determine the preference base for either PCV10 or PCV13. The pivotal assumptions and results of these analyses also depended on which manufacturer sponsored the study. A more thorough exploration of uncertainty should be made in future analyses on this subject, as we lack understanding to adequately model herd and serotype replacement effects to reliably predict the population impact of PCVs. The introduction of further improved PCVs in an environment of evolving antibiotic resistance and under the continuing influence of previous PCVs implies that the complexity and data requirements for relevant analyses will further increase. Decision makers using these analyses should not just rely on an analysis from a single manufacturer. Copyright © 2015 Elsevier

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

Energy Technology Data Exchange (ETDEWEB)

Lieberman, Craig M. [Department of Chemistry, University at Albany, Albany, New York 12222, United States; Barry, Matthew C. [Department of Chemistry, University at Albany, Albany, New York 12222, United States; Wei, Zheng [Department of Chemistry, University at Albany, Albany, New York 12222, United States; Rogachev, Andrey Yu. [Department; Wang, Xiaoping [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States; Liu, Jun-Liang [CNRS, CRPP, UPR 8641, F-33600 Pessac, France; Univ. Bordeaux, UPR 8641, F-33600 Pessac, France; MOE Key Lab of Bioinorganic and Synthetic Chemistry,; Clérac, Rodolphe [CNRS, CRPP, UPR 8641, F-33600 Pessac, France; Univ. Bordeaux, UPR 8641, F-33600 Pessac, France; Chen, Yu-Sheng [ChemMatCARS, Center for Advanced Radiation; Filatov, Alexander S. [Department; Dikarev, Evgeny V. [Department of Chemistry, University at Albany, Albany, New York 12222, United States

2017-07-31

A series of mixed-valent, heterometallic (mixed-transition metal) diketonates that can be utilized as prospective volatile single-source precursors for the low-temperature preparation of M_xM'_3–xO₄ spinel oxide materials is reported. Three iron–cobalt complexes with Fe/Co ratios of 1:1, 1:2, and 2:1 were synthesized by several methods using both solid-state and solution reactions. On the basis of nearly quantitative reaction yields, elemental analyses, and comparison of metal–oxygen bonds with those in homometallic analogues, heterometallic compounds were formulated as [Fe^III(acac)₃][Co^II(hfac)₂] (1), [Co^II(hfac)₂][Fe^III(acac)₃][Co^II(hfac)₂] (2), and [Fe^II(hfac)₂][Fe^III(acac)₃][Co^II(hfac)₂] (3). In the above heteroleptic complexes, the Lewis acidic, coordinatively unsaturated CoII/FeII centers chelated by two hexafluoroacetylacetonate (hfac) ligands maintain bridging interactions with oxygen atoms of acetylacetonate (acac) groups that chelate the neighboring Fe^III metal ion. Preliminary assignment of Fe and Co positions/oxidation states in 1–3 drawn from X-ray structural investigation was corroborated by a number of complementary techniques. Single-crystal resonant synchrotron diffraction and neutron diffraction experiments unambiguously confirmed the location of Fe and Co sites in the molecules of dinuclear (1) and trinuclear (2) complexes, respectively. Direct analysis in real time mass spectrometry revealed the presence of Fe^III- and Co^II-based fragments in the gas phase upon evaporation of precursors 1 and 2 as well as of Fe^III, Fe^II, and Co^II species for complex 3. Theoretical investigation of two possible “valent isomers”, [Fe^III(acac)₃

Preparation and certification of a reference uranium

International Nuclear Information System (INIS)

Anon.

1979-06-01

The CEA Analysis Coordination has produced a reference uranium metal of guaranteed minimum uranium content. The metal was purified by electro-refining in fused salt baths and the dendrites obtained were cast in the form of an ingot by electron bombardment. The ingot was rolled and cut into pieces of mass between 0.5 g and 1.5 g, and each piece conditioned in a glass ampoule under primary vacuum. The total number of reference samples is about 4500. The uranium content was inferred from the impurity concentration determined by spark mass spectrometry and atomic or molecular adsorption spectrophotometry and from the gas concentration determined by specific methods. A certificate of guarantee gives instructions for the use of these reference samples [fr

A Study on Removal of Environmental Pollution Materials with Nano-scale Iron Particles

Energy Technology Data Exchange (ETDEWEB)

Lee, Myung Ho; Ahn, Hong Ju

2009-07-15

In this study, a method of nano-sized iron particles with zero valent state was developed. Also, the optimum conditions for the synthesis of silica based micro-particles were obtained for micro particle analysis. Basic physical data for standard particles were obtained in various synthesis conditions for mass production. From the experiment of removal of Pb in the solution with iron particles with zero valent state, most of Pb was removed from the solution over pH 7, as a result of reaction of Pb with iron particles with zero valent state. Nano sized iron particles with zero valent state obtained from this study will be apply for removing heavy metals and radionuclides as well as waste treatment and remediation for contaminated materials in the environment.

Proposal of reference stress for a surface flaw on a cylindrical component from a review-with-comparison of the local metal loss assessment rule between API 579-1 and the p-M diagram method

International Nuclear Information System (INIS)

Oyamada, Kenji; Konosu, Shinji; Ohno, Takashi

2011-01-01

The Remaining Strength Factor (RSF) approach in Part 5 of API 579-1/ASME FFS-1 is an assessment method for a cylindrical component with a local metal loss based on surface correction factors. Also, reference stress solutions that are applied in the Failure Assessment Diagram (FAD) method for a cylindrical component with a crack-like flaw are provided in Annex D using surface correction factors. In the recently-developed p-M diagram method, the reference stress solution for local metal loss evaluation in a cylindrical component is derived using bulging factors, which are similar but not identical to the surface correction factors used in API 579-1/ASME FFS-1. This paper describes the results of a comparative study among the RSF approach, reference stress solutions for the FAD method, and the p-M diagram method, in terms of plastic collapse evaluation of a cylindrical component. These results were compared with the FEA and experimental results to confirm how these estimated stresses could be validated. This study also involves recommended reference stress solutions for a cylindrical component with a crack-like flaw or a local metal loss, which should be adopted as fitness-for-service rules, and a discussion on the influence of the design margin of the construction code on allowable flaw depth. - Highlights: → We compared local metal loss assessment rule between API 579-1 and the p-M method. → Experiments and FEA verified the p-M estimate stress state around a flaw accurate. → API 579-1 for local metal loss may underestimate stress state for certain conditions. → Existing reference stresses for crack-like flaws may underestimate stress state too. → We propose the reference stress for a surface flaw subjected to pressure and moment.

Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts

Science.gov (United States)

Greczynski, G.; Primetzhofer, D.; Hultman, L.

2018-04-01

We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BE's) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar+ ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2-0.5 eV towards lower BE. These destructive effects of Ar+ ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table (3d, 4d, and 5d) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides.

Dechlorination of short chain chlorinated paraffins by nanoscale zero-valent iron.

Science.gov (United States)

Zhang, Zhi-Yong; Lu, Mang; Zhang, Zhong-Zhi; Xiao, Meng; Zhang, Min

2012-12-01

In this study, nanoscale zero-valent iron (NZVI) particles were synthesized and used for the reductive dehalogenation of short chain chlorinated paraffins (SCCPs) in the laboratory. The results show that the dechlorination rate of chlorinated n-decane (CP(10)) by NZVI increased with decreased solution pH. Increasing the loading of NZVI enhanced the dechlorination rate of CP(10). With an increase in temperature, the degradation rate increased. The reduction of CP(10) by NZVI was accelerated with increasing the concentration of humic acid up to 15 mg/L but then was inhibited. The dechlorination of CP(10) within the initial 18 h followed pseudo-first order rate model. The formation of intermediate products indicates a stepwise dechlorination pathway of SCCPs by NZVI. The carbon chain length and chlorination degree of SCCPs have a polynominal impact on dechlorination reactions. Copyright © 2012 Elsevier B.V. All rights reserved.

Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed?

NARCIS (Netherlands)

Wellenberg, Ruud H. H.; Donders, Johanna C. E.; Kloen, Peter; Beenen, Ludo F. M.; Kleipool, Roeland P.; Maas, Mario; Streekstra, Geert J.

2017-01-01

To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel

Analytical Characterisation of Nanoscale Zero-Valent Iron: A ...

Science.gov (United States)

Zero-valent iron nanoparticles (nZVI) have been widely tested as they are showing significant promise for environmental remediation. However, many recent studies have demonstrated that their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Both the mobility and reactivity of nZVI mainly depends on properties such as particle size, surface chemistry and bulk composition. In order to ensure efficient remediation, it is crucial to accurately assess and understand the implications of these properties before deploying these materials into contaminated environments. Many analytical techniques are now available to determine these parameters and this paper provides a critical review of their usefulness and limitations for nZVI characterisation. These analytical techniques include microscopy and light scattering techniques for the determination of particle size, size distribution and aggregation state, and X-ray techniques for the characterisation of surface chemistry and bulk composition. Example characterisation data derived from commercial nZVI materials is used to further illustrate method strengths and limitations. Finally, some important challenges with respect to the characterisation of nZVI in groundwater samples are discussed. In recent years, manufactured nanoparticles (MNPs) have attracted increasing interest for their potential applications in the treatment of contaminated soil and water. In compar

Aqueous phosphate removal using nanoscale zero-valent iron

International Nuclear Information System (INIS)

Almeelbi, Talal; Bezbaruah, Achintya

2012-01-01

Nanoscale zero-valent iron (NZVI) particles have been used for the remediation of a wide variety of contaminants. NZVI particles have high reactivity because of high reactive surface area. In this study, NZVI slurry was successfully used for phosphate removal and recovery. Batch studies conducted using different concentrations of phosphate (1, 5, and 10 mg PO 4 3− -P/L with 400 mg NZVI/L) removed ∼96 to 100 % phosphate in 30 min. Efficacy of the NZVI in phosphate removal was found to 13.9 times higher than micro-ZVI (MZVI) particles with same NZVI and MZVI surface area concentrations used in batch reactors. Ionic strength, sulfate, nitrate, and humic substances present in the water affected in phosphate removal by NZVI but they may not have any practical significance in phosphate removal in the field. Phosphate recovery batch study indicated that better recovery is achieved at higher pH and it decreased with lowering of the pH of the aqueous solution. Maximum phosphate recovery of ∼78 % was achieved in 30 min at pH 12. The successful rapid removal of phosphate by NZVI from aqueous solution is expected to have great ramification for cleaning up nutrient rich waters.

The interactions between nanoscale zero-valent iron and microbes in the subsurface environment: A review

Energy Technology Data Exchange (ETDEWEB)

Xie, Yankai [College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082 (China); Dong, Haoran, E-mail: dongh@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082 (China); Zeng, Guangming; Tang, Lin; Jiang, Zhao; Zhang, Cong; Deng, Junmin; Zhang, Lihua; Zhang, Yi [College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082 (China)

2017-01-05

Highlights: • The interactions between various microbes and NZVI were summarized. • The adverse and positive effects of NZVI on the growth of microbes were reviewed. • The synergistic effects of NZVI and bacteria on pollutant removal were reviewed. • The effects of iron-reducing bacteria on the aged NZVI were reviewed. • Future challenges to study the interactions between NZVI and microbes are suggested. - Abstract: Nanoscale zero-valent iron (NZVI) particles, applied for in-situ subsurface remediation, are inevitable to interact with various microbes in the remediation sites directly or indirectly. This review summarizes their interactions, including the effects of NZVI on microbial activity and growth, the synergistic effect of NZVI and microbes on the contaminant removal, and the effects of microbes on the aging of NZVI. NZVI could exert either inhibitive or stimulative effects on the growth of microbes. The mechanisms of NZVI cytotoxicity (i.e., the inhibitive effect) include physical damage and biochemical destruction. The stimulative effects of NZVI on certain bacteria are associated with the creation of appropriate living environment, either through providing electron donor (e.g., H{sub 2}) or carbon sources (e.g., the engineered organic surface modifiers), or through eliminating the noxious substances that can cause bactericidal consequence. As a result of the positive interaction, the combination of NZVI and some microbes shows synergistic effect on contaminant removal. Additionally, the aged NZVI can be utilized by some iron-reducing bacteria, resulting in the transformation of Fe(III) to Fe(II), which can further contribute to the contaminant reduction. However, the Fe(III)-reduction process can probably induce environmental risks, such as environmental methylation and remobilization of the previously entrapped heavy metals.

The interactions between nanoscale zero-valent iron and microbes in the subsurface environment: A review

International Nuclear Information System (INIS)

Xie, Yankai; Dong, Haoran; Zeng, Guangming; Tang, Lin; Jiang, Zhao; Zhang, Cong; Deng, Junmin; Zhang, Lihua; Zhang, Yi

2017-01-01

Highlights: • The interactions between various microbes and NZVI were summarized. • The adverse and positive effects of NZVI on the growth of microbes were reviewed. • The synergistic effects of NZVI and bacteria on pollutant removal were reviewed. • The effects of iron-reducing bacteria on the aged NZVI were reviewed. • Future challenges to study the interactions between NZVI and microbes are suggested. - Abstract: Nanoscale zero-valent iron (NZVI) particles, applied for in-situ subsurface remediation, are inevitable to interact with various microbes in the remediation sites directly or indirectly. This review summarizes their interactions, including the effects of NZVI on microbial activity and growth, the synergistic effect of NZVI and microbes on the contaminant removal, and the effects of microbes on the aging of NZVI. NZVI could exert either inhibitive or stimulative effects on the growth of microbes. The mechanisms of NZVI cytotoxicity (i.e., the inhibitive effect) include physical damage and biochemical destruction. The stimulative effects of NZVI on certain bacteria are associated with the creation of appropriate living environment, either through providing electron donor (e.g., H_2) or carbon sources (e.g., the engineered organic surface modifiers), or through eliminating the noxious substances that can cause bactericidal consequence. As a result of the positive interaction, the combination of NZVI and some microbes shows synergistic effect on contaminant removal. Additionally, the aged NZVI can be utilized by some iron-reducing bacteria, resulting in the transformation of Fe(III) to Fe(II), which can further contribute to the contaminant reduction. However, the Fe(III)-reduction process can probably induce environmental risks, such as environmental methylation and remobilization of the previously entrapped heavy metals.

Catalytic transformation of functionalized carboxylic acids using multifunctional rhenium complexes.

Science.gov (United States)

Naruto, Masayuki; Agrawal, Santosh; Toda, Katsuaki; Saito, Susumu

2017-06-13

Carboxylic acids (CAs) are one of the most ubiquitous and important chemical feedstocks available from biorenewable resources, CO 2 , and the petrochemical industry. Unfortunately, chemoselective catalytic transformations of CH n CO 2 H (n = 1-3) groups into other functionalities remain a significant challenge. Herein, we report rhenium V complexes as extremely effective precatalysts for this purpose. Compared to previously reported heterogeneous and homogeneous catalysts derived from high- or low-valent metals, the present method involves a α-C-H bond functionalization, a hydrogenation, and a hydrogenolysis, which affords functionalized alcohols with a wide substrate scope and high chemoselectivity under relatively mild reaction conditions. The results represent an important step toward a paradigm shift from 'low-valent' to 'high-valent' metal complexes by exploring a new portfolio of selective functional group transformations of highly oxygenated organic substrates, as well as toward the exploitation of CAs as a valuable biorenewable feedstock.

Kinetic and Thermodynamics of Methylene Blue Adsorption onto Zero Valent Iron Supported on Mesoporous Silica

Directory of Open Access Journals (Sweden)

Atyaf Khalid Hameed

2016-08-01

Full Text Available Zero valent iron supported on mesoporous silicanano particles (NZVI/MSNs was prepared by the aqueous phase borohydride reduction methods. Prior to the reduction, mesoporous silica nanoparticles (MSNs were prepared through the activation of fumed silica with concentrated HCl by refluxing at 90 °C. FTIR, XRD, FESEM, EDX and BET were used to characterize theadsorbents prepared. BET surface areas of MSNs, NZVI, and NZVI/MSNs were 126, 41, and 72 m2/g for, respectively. The performance of NZVI/MSNs as adsorbent was examined by adsorption of methylene blue (MB, performed in series of batch experiments. In the kinetic studies, pseudo first order and pseudo second order kinetic models were examined. The pseudo second order equation provided the best fit with the experimental data. Thermodynamic studies indicated that the adsorption process is endothermic with ΔH° was 90.53 kJ/mol. Positive ΔS° (300 J/mol and negative ΔG° (-6.42 kJ/mol was recorded, indicating the spontaneous of the adsorption process and naturally favorable. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th March 2016; Revised: 18th March 2016; Accepted: 18th March 2016 How to Cite: Hameed, A.K., Dewayanto, N., Dongyun, D., Nordin, M.R., Mohd Hasbi Ab. Rahim, M.H.A. (2016. Kinetic and Thermodynamics of Methylene Blue Adsorption onto Zero Valent Iron Supported on Mesoporous Silica. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 250-261 (doi:10.9767/bcrec.11.2.443.250-261 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.443.250-261

Nanochemistry of metals

International Nuclear Information System (INIS)

Sergeev, Gleb B

2001-01-01

The results of studies on the nanochemistry of metals published in recent years are generalised. Primary attention is centred on the methods for the synthesis of nanoparticles and their chemical reactions. The means of stabilisation of nanoparticles which involve individual metals and incorporate atoms of several metals are considered as well as their physicochemical properties. Self-assembling processes of nanoparticles are described. The prospects of using metal nanoparticles in semiconductor devices, catalysis, biology and medicine are discussed. The bibliography includes 165 references.

Tetrylones: An Intriguing Class of Monoatomic Zero-valent Group 14 Compounds.

Science.gov (United States)

Majhi, Paresh Kumar; Sasamori, Takahiro

2018-02-13

Tetrylones (ylidones) represent a class of zero-valent group 14 compounds with the general formula EL 2 (E=C, Si, Ge, Sn, or Pb; L=neutral σ-donating ligand), wherein the tetrel atom, E(0), possess its four valence electrons in the form of two electron lone pairs, and is moreover coordinated by two ligands (L) via donor-acceptor interactions (L→E←L). This review focuses on the synthesis, structure, reactivity, and computational examination of the isolable heavier tetrylones (Si, Ge, Sn) that have been discovered recently. A comprehensive review on carbone chemistry is beyond the scope of this review. It should also be noted that tetrylones contain two different types of lone pairs, that is, one that exhibits p-type and one that exhibits s-type characteristics. Different behavior should thus be expected when these lone pairs react with Lewis acids. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Immunogenicity and safety of the 9-valent HPV vaccine in men

DEFF Research Database (Denmark)

Castellsagué, X; Giuliano, A R; Goldstone, S

2015-01-01

OBJECTIVES: This study was designed to evaluate the immunogenicity and tolerability of a prophylactic 9-valent HPV (types 6/11/16/18/31/33/45/52/58) VLP (9vHPV) vaccine in young men 16-26 years of age in comparison to young women 16-26 years of age (the population that was used to establish 9v......HPV vaccine efficacy). Safety and immunogenicity data from this study will be used to bridge 9vHPV vaccine efficacy findings in 16-26 year old women to 16-26 year old men. METHODS: This study enrolled 1106 heterosexual men (HM) and 1101 women who had not yet received HPV vaccination. In addition, 313 men...... having sex with men (MSM) were enrolled and were evaluated separately for immunogenicity because previous results showed that antibody responses to quadrivalent HPV (types 6/11/16/18) VLP (qHPV) vaccine were lower in MSM than in HM. All subjects were administered a 3-dose regimen (Day 1, Month 2, Month 6...

Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed?

Science.gov (United States)

Wellenberg, Ruud H H; Donders, Johanna C E; Kloen, Peter; Beenen, Ludo F M; Kleipool, Roeland P; Maas, Mario; Streekstra, Geert J

2017-08-25

To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel tibia plate and a titanium intramedullary nail respectively. Virtual monochromatic images were analyzed from 70 to 190 keV. Region-of-interest (ROI), used to determine fluctuations and inaccuracies in CT numbers of soft tissues and bone, were placed in muscle, fat, cortical bone and intramedullary tibia canal. The stainless-steel implant resulted in more pronounced metal artifacts compared to both titanium implants. CT number inaccuracies in 70 keV reference images were minimized at 130, 180 and 190 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Noise, measured as the standard deviation of pixels within a ROI, was minimized at 130, 150 and 140 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Tailoring dual-energy CT protocols using implant specific virtual monochromatic images minimizes fluctuations and inaccuracies in CT numbers in bone and soft tissues compared to non-metal reference scans.

Preparation and certification of Sargasso seaweed reference material

Energy Technology Data Exchange (ETDEWEB)

Okamoto, Kensaku

1988-01-01

Sargasso seaweed reference material was prepared from Sargassum felvellum obtained from an unpolluted area in Japan. The sargasso samples were washed, freeze-dried, pulverized, sieved to pass a 80-mesh screen and finally homogenized. Collaborative studies on the elemental analysis of the sargasso reference material were performed using various analytical techniques. Certified values are provided for Ag, As, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Rb, Sr, V and Zn, based on results of determinations by at least three independent analytical techniques. Reference values are reported for Al, Br, Cl, Cr, Cs, Hg, I, P, S, Sb, Sc, Se, Ti and U. The sargasso certified reference material contains high levels of alkali metals, alkaline earth metals, I, Br, As and U, while the concentration of trace elements may be considered to be at the lower end of the range of reported values for marine brown algae. The sargasso sample will be of practical use in marine and environmental sciences as a certified reference material having an elemental composition close to background levels.

Well-Dispersed Nanoscale Zero-Valent Iron Supported in Macroporous Silica Foams: Synthesis, Characterization, and Performance in Cr(VI Removal

Directory of Open Access Journals (Sweden)

Chaoxia Zhao

2017-01-01

Full Text Available Well-dispersed nanoscale zero-valent iron (NZVI supported inside the pores of macroporous silica foams (MOSF composites (Mx-NZVI has been prepared as the Cr(VI adsorbent by simply impregnating the MOSF matrix with ferric chloride, followed by the chemical reduction with NaHB4 in aqueous solution at ambient atmosphere. Through the support of MOSF, the reactivity and stability of NZVI are greatly improved. Transmission electron microscopy (TEM results show that NZVI particles are spatially well-dispersed with a typical core-shell structure and supported inside MOSF matrix. The N2 adsorption-desorption isotherms demonstrate that the Mx-NZVI composites can maintain the macroporous structure of MOSF and exhibit a considerable high surface area (503 m2·g−1. X-ray photoelectron spectroscopy (XPS and powder X-ray diffraction (XRD measurements confirm the core-shell structure of iron nanoparticles composed of a metallic Fe0 core and an Fe(II/Fe(III species shell. Batch experiments reveal that the removal efficiency of Cr(VI can reach 100% when the solution contains 15.0 mg·L−1 of Cr(VI at room temperature. In addition, the solution pH and the composites dosage can affect the removal efficiency of Cr(VI. The Langmuir isotherm is applicable to describe the removal process. The kinetic studies demonstrate that the removal of Cr(VI is consistent with pseudo-second-order kinetic model.

Cost-Effectiveness of Vaccinating Immunocompetent ≥65 Year Olds with the 13-Valent Pneumococcal Conjugate Vaccine in England.

Directory of Open Access Journals (Sweden)

Albert Jan van Hoek

Full Text Available Recently a large clinical trial showed that the use of 13-valent pneumococcal conjugate vaccine (PCV13 among immunocompetent individuals aged 65 years and over was safe and efficacious. The aim of this study was to assess the cost-effectiveness of vaccinating immunocompetent 65 year olds with PCV13 vaccine in England. England is a country with universal childhood pneumococcal conjugate vaccination programme in place (7-valent (PCV7 since 2006 and PCV13 since 2010, as well as a 23-valent pneumococcal polysaccharide (PPV23 vaccination programme targeting clinical risk-groups and those ≥65 years.A static cohort cost-effectiveness model was developed to follow a cohort of 65 year olds until death, which will be vaccinated in the autumn of 2016 with PCV13. Sensitivity analysis was performed to test the robustness of the results.The childhood vaccination programme with PCV7 has induced herd protection among older unvaccinated age groups, with a resultant low residual disease burden caused by PCV7 vaccine types. We show similar herd protection effects for the 6 additional serotypes included in PCV13, and project a new low post-introduction equilibrium of vaccine-type disease in 2018/19. Applying these incidence projections for both invasive disease and community-acquired pneumonia (CAP, and using recent measures of vaccine efficacy against these endpoints for ≥65 year olds, we estimate that vaccination of a cohort of immunocompetent 65 year olds with PCV13 would directly prevent 26 cases of IPD, 69 cases of CAP and 15 deaths. The associated cost-effectiveness ratio is £257,771 per QALY gained (using list price of £49.10 per dose and £7.51 administration costs and is therefore considered not cost-effective. To obtain a cost-effective programme the price per dose would need to be negative. The results were sensitive to disease incidence, waning vaccine protection and case fatality rate; despite this, the overall conclusion was robust

Impact of the Valence Charge of Transition Metals on the Cobalt- and Rhodium-Catalyzed Synthesis of Indenamines, Indenols, and Isoquinolinium Salts: A Catalytic Cycle Involving MIII/MV [M = Co, Rh] for [4+2] Annulation.

Science.gov (United States)

Chiou, Mong-Feng; Jayakumar, Jayachandran; Cheng, Chien-Hong; Chuang, Shih-Ching

2018-06-13

Reaction mechanisms for the synthesis of indenamines, indenols, and isoquinolinium salts through cobalt- and rhodium-catalysis were investigated using density functional theory calculations. We found that the valence charge of transition metals dramatically influences the reaction pathways. Catalytic reactions involving lower-oxidation-state transition metals (M I /M III , M = Co and Rh) generally favor a [3+2] cyclization pathway, whereas those involving higher oxidation states (M III /M V ) proceed through a [4+2] cyclization pathway. A catalytic cycle with novel M III /M V as a crucial species was successfully revealed for isoquinolinium salts synthesis, which highly valent M V was not only encountered in the [RhCp*]-catalysis but also in the [CoCp*]-catalysis.

Degradation of trichloroethylene (TCE) by nanoscale zero-valent iron (nZVI) immobilized in alginate bead

Energy Technology Data Exchange (ETDEWEB)

Kim, Hojeong [Division of Water and Environment, Korea Environment Institute (KEI), Seoul (Korea, Republic of); Hong, Hye-Jin; Jung, Juri; Kim, Seong-Hye [Dept. of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejon (Korea, Republic of); Yang, Ji-Won, E-mail: jwyang@kaist.ac.kr [Dept. of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejon (Korea, Republic of)

2010-04-15

Abstracts: Nowadays, many researchers have studied the environmental application of the nanoscale zero-valent iron (nZVI) and several field applications for the groundwater remediation have been reported. Still, there are many concerns on the fate and transport of the nZVI and the corresponding risks. To avoid such concerns, it was investigated to immobilize nZVI in a support and then it was applied to degrade trichloroethylene (TCE). The nZVI and palladium-doped nZVI (Fe(0)- and Fe/Pd-alginate) were immobilized in the alginate bead where ferric and barium ions are used as the cross-linking cations of the bead. According to TEM (transmission electron microscopy), the size of the immobilized ZVI was as small as a few nanometers. From the surface analysis of the Fe/Pd-alginate, it is found that the immobilized nZVI has the core-shell structure. The core is composed of single crystal Fe{sup 0}, while most of irons on the surface are oxidized to Fe{sup 3+}. When 50 g/L of Fe/Pd-alginate (3.7 g Fe/L) was introduced to the aqueous solution, >99.8% of TCE was removed and the release of metal from the support was <3% of the loaded iron. The removal of TCE by Fe/Pd-alginate followed pseudo-first-order kinetics. The observed pseudo-first-order reaction constant (k{sub obs}) of Fe/Pd-alginate was 6.11 h{sup -1} and the mass normalized rate constant (k{sub m}) was 1.6 L h{sup -1} g{sup -1}. The k{sub m} is the same order of magnitude with that of iron nanoparticles. In conclusion, it is considered that Fe/Pd-alginate can be used efficiently in the treatment of chlorinated solvent.

Transfer of heavy metals in the food chain earthworm Black-tailed godwit (Limosa limosa): Comparison of a polluted and a reference site in The Netherlands

Energy Technology Data Exchange (ETDEWEB)

Roodbergen, Maja [Department of Ecology and Environment, ALTERRA, PO Box 47, 6700 AA, Wageningen (Netherlands); Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, Haren (Netherlands)], E-mail: maja.roodbergen@sovon.nl; Klok, Chris; Hout, Annemariet van der [Department of Ecology and Environment, ALTERRA, PO Box 47, 6700 AA, Wageningen (Netherlands)

2008-12-01

The Black-tailed godwit (Limosa limosa) is a migratory wader that favours wet meadows for breeding. The species has a Red List status in The Netherlands, as it strongly declined in numbers since the 1960s. Intensification of agriculture and land use change resulting in habitat loss are considered major causes of this decline. In some areas the breeding habitat is contaminated with heavy metals. Adult godwits mainly feed on earthworms in the breeding season, which are known to accumulate heavy metals from the soil. In this paper we investigate the transfer of heavy metals from the soil to the Black-tailed godwit, which may have an additive negative effect on the viability of local populations. We measured heavy metal concentrations in soil, earthworms, and godwit eggs and feathers at a polluted and a reference site. The results suggest that Lead, Mercury and Cadmium are transferred from the soil to godwits even though the species spends only a few months in the breeding area during the year.

Transfer of heavy metals in the food chain earthworm Black-tailed godwit (Limosa limosa): Comparison of a polluted and a reference site in The Netherlands

International Nuclear Information System (INIS)

Roodbergen, Maja; Klok, Chris; Hout, Annemariet van der

2008-01-01

The Black-tailed godwit (Limosa limosa) is a migratory wader that favours wet meadows for breeding. The species has a Red List status in The Netherlands, as it strongly declined in numbers since the 1960s. Intensification of agriculture and land use change resulting in habitat loss are considered major causes of this decline. In some areas the breeding habitat is contaminated with heavy metals. Adult godwits mainly feed on earthworms in the breeding season, which are known to accumulate heavy metals from the soil. In this paper we investigate the transfer of heavy metals from the soil to the Black-tailed godwit, which may have an additive negative effect on the viability of local populations. We measured heavy metal concentrations in soil, earthworms, and godwit eggs and feathers at a polluted and a reference site. The results suggest that Lead, Mercury and Cadmium are transferred from the soil to godwits even though the species spends only a few months in the breeding area during the year

Specificity in liquid metal induced embrittlement

CSIR Research Space (South Africa)

Fernandes, PJL

1996-12-01

Full Text Available One of the most intriguing features of liquid metal induced embrittlement (LMIE) is the observation that some liquid metal-solid metal couples are susceptible to embrittlement, while others appear to be immune. This is referred to as the specificity...

Alkali metal control over N-N cleavage in iron complexes.

Science.gov (United States)

Grubel, Katarzyna; Brennessel, William W; Mercado, Brandon Q; Holland, Patrick L

2014-12-03

Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber-Bosch process, there is still ambiguity about the number of Fe atoms involved during the N-N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe-N2 and Fe-nitride cores. Surprisingly, adding more equivalents of reductant to the system gives a product in which the N-N bond is not cleaved, indicating that the reducing power is not the most important factor that determines the extent of N2 activation. On the other hand, the results suggest that the size of the alkali metal cation can control the number of Fe atoms that can approach N2, which in turn controls the ability to achieve N2 cleavage. The accumulated results indicate that cleaving the triple N-N bond to nitrides is facilitated by simultaneous approach of least three low-valent Fe atoms to a single molecule of N2.

The cost-effectiveness of a 13-valent pneumococcal conjugate vaccination for infants in England.

Science.gov (United States)

van Hoek, Albert Jan; Choi, Yoon Hong; Trotter, Caroline; Miller, Elizabeth; Jit, Mark

2012-11-26

In the immunisation schedule in England and Wales, the 7-valent pneumococcal conjugate vaccine (PCV-7) was replaced by the 13-valent vaccine (PCV-13) in April 2010 after having been used since September 2006. The introduction of PCV-7 was informed by a cost effectiveness analysis using an infectious disease model which projected herd immunity and serotype replacement effects based on the post-vaccine experience in the United States at that time. To investigate the cost effectiveness of the introduction of PCV-13. Invasive disease incidence following vaccination was projected from a dynamic infectious disease model, and combined with serotype specific disease outcomes obtained from a large hospital dataset linked to laboratory confirmation of invasive pneumococcal disease. The economic impact of replacing PCV-7 with PCV-13 was compared to stopping the use of pneumococcal conjugate vaccination altogether. Discontinuing PCV-7 would lead to a projected increase in invasive pneumococcal disease, costs and loss of quality of life compared to the introduction of PCV-13. However under base case assumptions (assuming no impact on non-invasive disease, maximal competition between vaccine and non-vaccine types, time horizon of 30 years, vaccine price of £49.60 a dose+£7.50 administration costs and discounting of costs and benefits at 3.5%) the introduction of PCV-13 is only borderline cost effective compared to a scenario of discontinuing of PCV-7. The intervention becomes more cost-effective when projected impact of non-invasive disease is included or the discount factor for benefits is reduced to 1.5%. To our knowledge this is the first evaluation of a transition from PCV-7 to PCV-13 based on a dynamic model. The cost-effectiveness of such a policy change depends on a number of crucial assumptions for which evidence is limited, particularly the impact of PCV-13 on non-invasive disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

Adsorption of precious metals in water by dendrimer modified magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Yen, Chia-Hsin [Institute of Environmental Engineering, National Chiao Tung University, 300 Hsinchu, Taiwan (China); Lien, Hsing-Lung, E-mail: lien.sam@nuk.edu.tw [Department of Civil and Environmental Engineering, National University of Kaohsiung, 811 Kaohsiung, Taiwan (China); Chung, Jung-Shing [Department of Civil and Environmental Engineering, National University of Kaohsiung, 811 Kaohsiung, Taiwan (China); Yeh, Hund-Der [Institute of Environmental Engineering, National Chiao Tung University, 300 Hsinchu, Taiwan (China)

2017-01-15

Highlights: • A reusable magnetic nano-adsorbent is prepared for precious metal adsorption. • The nano-adsorbent (MNP-G3) is synthesized by magnetic nanoparticles and dendrimer. • Higher valent ions show higher adsorption capacity by MNP-G3 suggesting complexation involved. • The pseudo second-order model best describe the adsorption kinetics. • MNP-G3 modified by EDTA significantly improve its adsorption ability for Ag(I). - Abstract: Magnetic nanoparticles modified by third-generation dendrimers (MNP-G3) and MNP-G3 further modified by ethylenediaminetetraacetic acid (EDTA) (MNP-G3-EDTA) were conducted to investigate their ability for recovery of precious metals (Pd(IV), Au(III), Pd(II) and Ag(I)) in water. Experiments were carried out using batch reactors for the studies of adsorption kinetics, adsorption isotherms, competitive adsorption and regeneration. The pseudo second-order model is the best-fit model among others suggesting that the adsorption of precious metals by MNP-G3 in water is a chemisorption process. Three adsorption isotherms namely Langmuir, Freundlich and Dubinin-Radushkevich isotherm were examined and the results showed the similarities and consistency of both linear and nonlinear analyses. Pd(IV) and Au(III) with higher valence exhibited relatively better adsorption efficiency than Pd(II) and Ag(I) with lower valence suggesting that the adsorption of precious metals by MNP-G3 is a function of valence. In the presence of the competing ion Zn(II), the adsorption efficiency of MNP-G3 for all four precious metals was declined significantly. The use of MNP-G3-EDTA revealed an increase in the adsorption efficiency for all four precious metals. However, the low selectivity of MNP-G3 towards precious metals was not enhanced by the modification of EDTA onto the MNP-G3. The regeneration of metal-laden MNP-G3 can be readily performed by using 1.0% HCl solution as a desorbent solution.

Efficacy, immunogenicity, and safety of a 9-valent human papillomavirus vaccine in Latin American girls, boys, and young women

OpenAIRE

Ángela María Ruiz-Sternberg; Edson D. Moreira, Jr; Jaime A. Restrepo; Eduardo Lazcano-Ponce; Robinson Cabello; Arnaldo Silva; Rosires Andrade; Francisco Revollo; Santos Uscanga; Alejandro Victoria; Ana María Guevara; Joaquín Luna; Manuel Plata; Claudia Nossa Dominguez; Edison Fedrizzi

2018-01-01

Background: A 9-valent human papillomavirus (HPV6/11/16/18/31/33/45/52/58; 9vHPV) vaccine was developed to expand coverage of the previously developed quadrivalent (HPV6/11/16/18; qHPV) vaccine. Methods: Efficacy, immunogenicity, and safety outcomes were assessed in Latin American participants enrolled in 2 international studies of the 9vHPV vaccine, including a randomized, double-blinded, controlled with qHPV vaccine, efficacy, immunogenicity, and safety study in young women aged 16–26 years...

Integrated Nanozero Valent Iron and Biosurfactant-Aided Remediation of PCB-Contaminated Soil

Directory of Open Access Journals (Sweden)

He Zhang

2016-01-01

Full Text Available Polychlorobiphenyls (PCBs have been identified as environmental hazards for years. Due to historical issues, a considerable amount of PCBs was released deep underground in Canada. In this research, a nanoscale zero valent iron- (nZVI- aided dechlorination followed by biosurfactant enhanced soil washing method was developed to remove PCBs from soil. During nZVI-aided dechlorination, the effects of nZVI dosage, initial pH level, and temperature were evaluated, respectively. Five levels of nZVI dosage and two levels of initial pH were experimented to evaluate the PCB dechlorination rate. Additionally, the temperature changes could positively influence the dechlorination process. In soil washing, the presence of nanoiron particles played a key role in PCB removal. The crude biosurfactant was produced using a bacterial stain isolated from the Atlantic Ocean and was applied for soil washing. The study has led to a promising technology for PCB-contaminated soil remediation.

Immunogenicity, safety and reactogenicity of a booster dose of the 10-valent pneumococcal Nontypeable H. influenzae Protein D conjugate vaccine coadministered with DTPa-IPV-Hib in Dutch children

NARCIS (Netherlands)

Van Den Bergh, Menno R.; Spijkerman, Judith; François, Nancy; Swinnen, Kristien; Borys, Dorota; Schuerman, Lode; Veenhoven, Reinier H.; Sanders, Elisabeth A M

2016-01-01

Background: Immune responses and safety profiles may be affected when vaccines are coadministered. We evaluated the immunogenicity, safety and reactogenicity of a booster dose of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D-conjugate (PHiD-CV; Synflorix GSK Vaccines) and

General health, otitis media, nasopharyngeal carriage and middle ear microbiology in Northern Territory Aboriginal children vaccinated during consecutive periods of 10-valent or 13-valent pneumococcal conjugate vaccines.

Science.gov (United States)

Leach, Amanda J; Wigger, Christine; Beissbarth, Jemima; Woltring, Donna; Andrews, Ross; Chatfield, Mark D; Smith-Vaughan, Heidi; Morris, Peter S

2016-07-01

This study aims to monitor the prevalence of suppurative otitis media in remote Indigenous communities after introduction of 13-valent pneumococcal conjugate vaccine (PCV13) in October 2011. We previously reported a decline in suppurative OM following replacement of PCV7 by 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) in October 2009. We continued regular surveillance in remote Indigenous communities between February 2010 and August 2013. This analysis reports the general health, otitis media (OM), nasopharyngeal (NP) carriage and middle ear microbiology in children less than 36 months of age who received a primary course of at least two doses of PHiD-CV10 or PCV13, and not more than one dose of another pneumococcal vaccine. Mean ages of 511 PHiD-CV10- and 140 PCV13-vaccinated children were 19 and 13 months, respectively. Most children received 3-dose non-mixed PCV schedules. At the time of assessment, general health was poor and prevalence of risk factors was high in both groups: overall, around 14% of children had scabies, 20% had impetigo, 59% had runny nose and 39% had cough. Average household size was 8 persons, and 60% of the mothers smoked. Bilaterally normal middle ears were detected in 10% and 7%, respectively. OM with effusion (OME), almost all bilateral, was diagnosed in 52% and 50%, any suppurative OM (acute OM or any tympanic membrane perforation [TMP]) in 37% and 41%, and TMP in 14% and 12%, respectively. Children in the PCV13 group had significantly less NP carriage of combined Streptococcus pneumoniae (Spn) and non-typeable Haemophilus influenzae (NTHi) (62% versus 51%) but significantly more polymicrobial (Spn and NTHi) middle ear cultures (12% versus 43%), and significantly less Staphylococcus aureus-positive middle ears (40% versus 7%). Although NP carriage of pneumococcal serotype 19A was low in the PCV13 group, serotypes 19F and 23F persist. The general health, particularly ear health, of little children

Ab Initio Studies of Metal Hexaboride Materials

Science.gov (United States)

Schmidt, Kevin M.

-terminations produce the lowest energies for di-cations of CaB6, SrB6 and BaB6, while tri-valent LaB6 minimizes its surface energy by arranging the metal ions in parallel rows on the surface. Studies involving hydrogen suggest that a single molecule per surface unit-cell is possible, and evidence is given for a dissociative adsorption pathway. Ternary mixtures of metal hexaborides containing two alkaline-earth cations in each crystal are also investigated with electronic structure methods. Multiple geometries are used to understand how spatial arrangements of cations within the mixture can affect properties related to stability. Bond-lengths within the boron framework are found to be heavily dependent upon the local cation environment, and energies taken at absolute zero suggest certain stoichiometries naturally lead to phase splitting.

Ferro zero: uma nova abordagem para o tratamento de águas contaminadas com compostos orgânicos poluentes Zero-valent iron: a new approach for treatment of waters contamined with organic pollutants

Directory of Open Access Journals (Sweden)

Wellington S. Pereira

2005-02-01

Full Text Available Anthropogenic pollution of groundwater and surface water has become a very serious environmental problem around the world. A wide range of toxic pollutants is recalcitrant to the conventional treatment methods, thus there is much interest in the development of more efficient remediation processes. Degradation of organic pollutants by zero-valent iron is one of the most promising approaches for water treatment, mainly because it is of low cost, easy to obtain and effective. After a general introduction to water pollution and current treatments, this work highlights the advances, applications and future trends of water remediation by zero-valent iron. Special attention is given to degradation of organochloride and nitroaromatic compounds, which are commonly found in textile and paper mill effluents.

Invasive pneumococcal disease : Clinical outcomes and patient characteristics 2-6 years after introduction of 7-valent pneumococcal conjugate vaccine compared to the pre-vaccine period, the Netherlands

NARCIS (Netherlands)

Wagenvoort, Gertjan H J; Sanders, Elisabeth A M; Vlaminckx, Bart J.; Elberse, Karin E.; de Melker, Hester E.; van der Ende, Arie; Knol, Mirjam J.

2016-01-01

Background Implementation of 7-valent pneumococcal conjugate vaccine (PCV7) in the Dutch national immunization program for infants led to a shift from vaccine to non-vaccine serotypes in invasive pneumococcal disease (IPD) in all age groups. We studied the impact of the serotype shift on clinical

An integrated technique using zero-valent iron and UV/H2O2 sequential process for complete decolorization and mineralization of C.I. Acid Black 24 wastewater

International Nuclear Information System (INIS)

Chang, M.-C.; Shu, H.-Y.; Yu, H.-H.

2006-01-01

The zero-valent iron (ZVI) reduction succeeds for decolorization, while UV/H 2 O 2 oxidation process results into mineralization, so that this study proposed an integrated technique by reduction coupling with oxidation process in order to acquire simultaneously complete both decolorization and mineralization of C.I. Acid Black 24. From the experimental data, the zero-valent iron addition alone can decolorize the dye wastewater yet it demanded longer time than ZVI coupled with UV/H 2 O 2 processes (Red-Ox). Moreover, it resulted into only about 30% removal of the total organic carbon (TOC), which was capable to be effectively mineralized by UV/H 2 O 2 process. The proposed sequential ZVI-UV/H 2 O 2 integration system cannot only effectively remove color and TOC in AB 24 wastewater simultaneously but also save irradiation power and time demand. Furthermore, the decolorization rate constants were about 3.77-4.0 times magnitude comparing with that by UV/H 2 O 2 process alone

Formation of a barrier to groundwater contaminants by the injection of zero-valent iron colloids: Suspension properties

International Nuclear Information System (INIS)

Kaplan, D.I.; Cantrell, K.J.; Wietsma, T.W.

1994-01-01

Zero-valent iron (Fe 0 ) (metallic iron) is a strong chemical reductant that is capable of degrading several halogenated-hydrocarbon compounds (e.g., trichloroethene and tetrachloroethene) and chemically reducing several highly mobile oxidized oxyanions and oxycations to their immobile forms. A series of studies was undertaken to develop methods of injecting micrometer-sized Fe 0 colloids into the subsurface environment to form a chemical barrier to these highly mobile contaminants. Forming a barrier by means of this technique may have the distinct advantage over traditional trench-and-fill technologies: it may be safer, more cost-effective, and may be used at greater depths. Several commercially available Fe 0 colloids were evaluated. One type was selected for further study based on its small size (1 to 2 microm) and the presence of an organic coating. This organic coating was weathered away within 7 days by Hanford ground water (CaCO 3 system, pH 8.1) and exposed the chemically active Fe 0 -colloid surface. Through the use of surfactants in a low ionic strength solution, the length of time that these extremely dense (7.8 g cm -3 ) colloids remained in suspension increased as much as 250%. The efficiency of quartz-sand columns to remove surfactant-coated Fe 0 colloids appeared to be at least partially controlled by injection rate; the filter coefficient values at injection rates of 6, 124, and 248 ml min -1 were 0.30, 0.05, and 0.02 cm -1 , respectively. Studies are underway to develop further understanding of this relationship and to determine the interactive effect of influent colloid concentration and injection flow rate on colloid placement in aquifer sediments for barrier formation

Comparison of the Efficiencies of Zero-Valent Iron Nanoparticles and Stabilized Iron Nanoparticles for Nitrate Reduction from Polluted Waters

Directory of Open Access Journals (Sweden)

Fatemeh Nooralivand

2015-12-01

Full Text Available The present study was conducted to evaluate the feasibility of zero-valent iron nanoparticles (ZVIN for the removal of nitrate from aqueous solutions. For this purpose, bare zero-valent iron nanoparticles (bare-ZVIN and CMC-ZVIN were synthesized using the borohydride reduction method and their morphological characteristics were examined via scanning electron microscopy (SEM, X-ray diffraction (XRD, and Fourier Transmission Infrared Spectroscopy (FTIR. The effects of pH of the aqueous solution, initial nitrate concentration, ZVIN concentration, and contact time on nitrate reduction were investigated as operational parameters and the kinetics of nitrate reduction was studied in batch experiments. The results showed that 93.65% of nitrate was removed by stabilized nanoparticles at pH=6 while non-stabilized nanoparticles at pH=2 were able to remove 85.55% of the nitrate.Furthermore, nitrate reduction was enhanced by increasing ZVIN concentration and contact time while it was decreased as a result of increasing initial nitrate concentration. The major product of nitrate reduction at an acidic pH was found to be ammonium; at an alkaline pH, however, nitrate was converted to nitrogen and nitrite production dropped to less than 2%. Kinetic analysis demonstrated that denitrification of nitrate by the nanoparticles fitted well with first-order and second-order reaction models. The results also demonstrated that the stabilized ZVI nanoparticles were more effective than bare-ZVIN for nitrate reduction in aqueous solutions.

Standard Reference Development of nuclear material for Tensile and Hardness Test Properties

International Nuclear Information System (INIS)

Choo, Y. S.; Kim, D. S.; Yoo, B. O.; Ahn, S. B.; Baik, S. J.; Chun, Y. B.; Kim, K. H.; Hong, K. P.; Ryu, W. S.

2007-12-01

Standard reference is a official approved data such a coefficient of physics, approved material properties, and etc., which should be analyzed and evaluated by scientific method to acquire official approval for accuracy and credibility of measured data and information. So it could be used broadly and continuously by various fields of nation and society. It is classified to effective standard reference, verified standard reference, and certified standard reference. There are sixteen fields in designated standard references such a physical chemistry field, material field, metal field, and the others. The standard reference of neutron irradiated nuclear structural material is classified to metal field. This report summarized the whole processes about data collection, data production, data evaluation and the suggestion of details evaluation technical standard for tensile and hardness properties, which were achieved by carry out the project 'nuclear material standard reference development' as a result

Standard Reference Development of nuclear material for Tensile and Hardness Test Properties

Energy Technology Data Exchange (ETDEWEB)

Choo, Y. S.; Kim, D. S.; Yoo, B. O.; Ahn, S. B.; Baik, S. J.; Chun, Y. B.; Kim, K. H.; Hong, K. P.; Ryu, W. S

2007-12-15

Standard reference is a official approved data such a coefficient of physics, approved material properties, and etc., which should be analyzed and evaluated by scientific method to acquire official approval for accuracy and credibility of measured data and information. So it could be used broadly and continuously by various fields of nation and society. It is classified to effective standard reference, verified standard reference, and certified standard reference. There are sixteen fields in designated standard references such a physical chemistry field, material field, metal field, and the others. The standard reference of neutron irradiated nuclear structural material is classified to metal field. This report summarized the whole processes about data collection, data production, data evaluation and the suggestion of details evaluation technical standard for tensile and hardness properties, which were achieved by carry out the project 'nuclear material standard reference development' as a result.

Metal sponge for cryosorption pumping applications

International Nuclear Information System (INIS)

Myneni, G.R.; Kneisel, P.

1995-01-01

A system has been developed for adsorbing gases at high vacuum in a closed area. The system utilizes large surface clean anodized metal surfaces at low temperatures to adsorb the gases. The large surface clean anodized metal is referred to as a metal sponge. The metal sponge generates or maintains the high vacuum by increasing the available active cryosorbing surface area. 4 figs

An Experimental Study of Micron-Size Zero-Valent Iron Emplacement in Permeable Porous Media Using Polymer-Enhanced Fluids

Energy Technology Data Exchange (ETDEWEB)

Oostrom, Mart; Wietsma, Thomas W.; Covert, Matthew A.; Vermeul, Vince R.

2005-12-22

At the Hanford Site, an extensive In Situ Redox Manipulation (ISRM) permeable reactive barrier was installed to prevent chromate from reaching the Columbia River. However, chromium has been detected in several wells, indicating a premature loss of the reductive capacity in the aquifer. One possible cause for premature chromate breakthrough is associated with the presence of high-permeability zones in the aquifer. In these zones, groundwater moves relatively fast and is able to oxidize iron more rapidly. There is also a possibility that the high-permeability flow paths are deficient in reducing equivalents (e.g. reactive iron), required for barrier performance. One way enhancement of the current barrier reductive capacity can be achieved is by the addition of micron-scale zero-valent iron to the high-permeability zones within the aquifer. The potential emplacement of zero-valent iron (Fe0) into high-permeability Hanford sediments (Ringold Unit E gravels) using shear-thinning fluids containing polymers was investigated in three-dimensional wedge-shaped aquifer models. Polymers were used to create a suspension viscous enough to keep the Fe0 in solution for extended time periods to improve colloid movement into the porous media without causing a permanent detrimental decrease in hydraulic conductivity. Porous media were packed in the wedge-shaped flow cell to create either a heterogeneous layered system with a high-permeability zone in between two low-permeability zones or a high-permeability channel surrounded by low-permeability materials. The injection flow rate, polymer type, polymer concentration, and injected pore volumes were determined based on preliminary short- and long-column experiments.

New reference materials improvement of methods of measurements

International Nuclear Information System (INIS)

Marchandise, H.

1985-01-01

The report summarizes the development of about 120 reference materials in a variety of fields (non ferrous metals, trace element analysis, food products, biomedical analysis, physical and technical properties of solid materials). The document also provides practical advice for trace element analyses, describes the principles followed for certifying reference materials and provides recommendations for their use

Pneumococcal meningitis: epidemiological profile pre- and post-introduction of the pneumococcal 10-valent conjugate vaccine

Directory of Open Access Journals (Sweden)

Tatiane E. Hirose

2015-03-01

Full Text Available Objectives: To evaluate the possible effects of the introduction of the pneumococcal conjugate 10-valent vaccine schedule in the state of Parana on pneumococcal meningitis cases and to assess the distribution of serotypes among cases. Method: Cross-sectional study with retrospective data collection of cases of pneumococcal meningitis in the state of Paraná reported to Sistema de Informação de Agravos de Notificação (SINAN, from 1998 to 2011. A total of 1,339 cases of pneumococcal meningitis were analyzed; 1,205 cases from the pre-vaccine period (1998-2009 were compared to 134 cases from the post-vaccine period (2010-2011. Descriptive and comparative statistical analyses (chi-squared test and prevalence ratio were performed using JMP 5.1.2 statistical software (JMP Statistical Discovery, North Carolina, USA and EPI INFO 6 (Centers for Disease Control and Prevention, Georgia, EUA. Results: There was a significant reduction in the mean rates of incidence and mortality in the general population. The analysis of cases in the pre- and post-vaccination periods in the age groups covered by vaccination (younger than 2 years showed significant reductions in incidence rates (6.01 cases/100,000 to 2.49 cases/100,000 individuals and mortality (1.85 cases/100,000 population to 0.47 cases/100,000 population, while the mean lethality rate did not change significantly. There was a significant reduction in cases whose serotypes are included in the vaccine (80.7% to 53.3%. Conclusion: Even after a short time of use, the 10-valent pneumococcal conjugate vaccine has already had a significant impact in reducing the incidence and mortality of meningitis cases among infants, as well as the reduction of cases whose serotypes are included in the vaccine. Resumo: Objetivos: Avaliar os possíveis efeitos da introdução da vacina pneumocócica conjugada 10 valente no calendário vacinal no Paraná sobre os casos de meningite pneumocócica; avaliar a distribuição dos

Evaluation of ABS resin disk certified reference materials for heavy metal analysis by x-ray fluorescence analysis

International Nuclear Information System (INIS)

Ohata, Masaki; Kidokoro, Toshihiro; Kurahashi, Masayasu; Hioki, Akiharu

2010-01-01

ABS resin disk certified reference materials (CRMs) for heavy-metal analysis (NMIJ CRM 8105-a, NMIJ CRM 8106-a, NMIJ CRM 8115-a and NMIJ CRM 8116-a) were evaluated using an energy dispersive X-ray fluorescence (ED-XRF) analysis. The homogeneities of elements for both among-disks and within-disk were evaluated by ED-XRF analysis without any sample pre-treatment, which were similar to those evaluated by ICP-MS analysis after a sample digenstion procedure. The normalized XRF sensitivities for Cd, Cr and Pb in different ABS resin disk CRMs were compared, and the differences among them for those ABS resin disks that have similar matrices were observed. Moreover, Hg in those ABS resin disk CRMs was stable for long-term X-ray irradiation during ED-XRF analysis. (author)

A mixed-valent uranium phosphonate framework containing U{sup IV}, U{sup V}, and U{sup VI}

Energy Technology Data Exchange (ETDEWEB)

Chen, Lanhua; Zheng, Tao; Wang, Yaxing; Diwu, Juan; Chai, Zhifang; Wang, Shuao [School for Radiological and interdisciplinary Sciences (RAD-X), Soochow University, Suzhou (China); Collaborative Innovation Center of Radiation Medicine, Jiangsu Higher Education Institutions, Suzhou (China); Bao, Songsong; Zheng, Limin [State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University (China); Zhang, Linjuan; Wang, Jianqiang [Shanghai Institute of Applied Physics and, Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Chinese Academy of Sciences, Shanghai (China); Liu, Hsin-Kuan [Department of Chemistry, National Central University, Jhongli (China); Albrecht-Schmitt, Thomas E. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL (United States)

2016-08-16

It is shown that U{sup V}O{sub 2}{sup +} ions can reside at U{sup VI}O{sub 2}{sup 2+} lattice sites during mild reduction and crystallization process under solvothermal conditions, yielding a complicated and rare mixed-valent uranium phosphonate compound that simultaneously contains U{sup IV}, U{sup V}, and U{sup VI}. The presence of uranium with three oxidation states was confirmed by various characterization techniques, including X-ray crystallography, X-ray photoelectron, electron paramagnetic resonance, FTIR, UV/Vis-NIR absorption, and synchrotron radiation X-ray absorption spectroscopy, and magnetism measurements. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The problem of oxidation state stabilisation and some regularities of a Periodic system of the elements

International Nuclear Information System (INIS)

Kiselev, Yurii M; Tretyakov, Yuri D

1999-01-01

The general principles of the concept of oxidation state stabilisation are formulated. Problems associated with the preparation and provision of the highest valent forms of transition elements are considered. The empirical data concerning the synthesis of new compounds of rare-earth elements and d elements in unusually high oxidation states are analysed. The possibility of occurrence of the oxidation states + 9 and + 10 for some elements (for example, for iridium and platinum in tetraoxo ions) are discussed. Approaches to the realisation of these states are outlined and it is demonstrated that solid phases or matrices containing alkali metal cations are the most promising systems for the stabilisation of these high oxidation states. Selected thermodynamic features typical of metal halides and oxides and the regularities of the changes in the extreme oxidation states of d elements are considered. The bibliography includes 266 references.

The role of nuclear methods in the study of surface compositions. Their use in the Community Bureau of Reference (BCR). Project on 'RMs for non-metals in non-ferrous metals'

International Nuclear Information System (INIS)

Quaglia, L.; Weber, G.

1979-01-01

The preparation of high-purity materials poses the problem of the analysis of the elements present at very low concentrations, even below 1 μg/g. For different analysis methods an important source of systematic errors is surface pollution. Although nuclear methods have shown to be well suited for the quantitative study of surfaces, their possibilities remain insufficiently known for most non-nuclear laboratories. Therefore, the first part of this report was conceived as a simple but complete as possible review of the existing nuclear techniques and gives also a description of their principal characteristics. The second part treats special uses of some of these techniques, especially the study of surface-mass interferences in the case of the assay of light elements in metals and alloys. This problem is discussed in the framework of the certification of reference materials, and is based upon experiences collected in a ten-year Community effort, which enabled the expression of general considerations concerning the treatment, conditioning and storage of reference materials

Cation-induced coagulation of aquatic plant-derived dissolved organic matter: Investigation by EEM-PARAFAC and FT-IR spectroscopy

Science.gov (United States)

Interaction and coagulation of plant-derived dissolved organic matter (DOM) by metal cations are important biogeochemical processes of organic matter in lake systems. Thus, coagulation and fractionation of plant-derived DOM by di- and tri-valent Ca, Al, and Fe ions were investigated. Metal ion-induc...

Zero-valent Fe confined mesoporous silica nanocarriers (Fe(0) @ MCM-41) for targeting experimental orthotopic glioma in rats

Science.gov (United States)

Shevtsov, M. A.; Parr, M. A.; Ryzhov, V. A.; Zemtsova, E. G.; Arbenin, A. Yu; Ponomareva, A. N.; Smirnov, V. M.; Multhoff, G.

2016-01-01

Mesoporous silica nanoparticles (MSNs) impregnated with zero-valent Fe (Fe(0) @ MCM-41) represent an attractive nanocarrier system for drug delivery into tumor cells. The major goal of this work was to assess whether MSNs can penetrate the blood-brain barrier in a glioblastoma rat model. Synthesized MSNs nanomaterials were characterized by energy dispersive X-ray spectroscopy, measurements of X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. For the detection of the MSNs by MR and for biodistribution studies MSNs were labeled with zero-valent Fe. Subsequent magnetometry and nonlinear-longitudinal-response-M2 (NLR-M2) measurements confirmed the MR negative contrast enhancement properties of the nanoparticles. After incubation of different tumor (C6 glioma, U87 glioma, K562 erythroleukemia, HeLa cervix carcinoma) and normal cells such as fibroblasts and peripheral blood mononuclear cells (PBMCs) MSNs rapidly get internalized into the cytosol. Intracellular residing MSNs result in an enhanced cytotoxicity as Fe(0) @ MCM-41 promote the reactive oxygen species production. MRI and histological studies indicated an accumulation of intravenously injected Fe(0) @ MCM-41 MSNs in orthotopic C6 glioma model. Biodistribution studies with measurements of second harmonic of magnetization demonstrated an increased and dose-dependent retention of MSNs in tumor tissues. Taken together, this study demonstrates that MSNs can enter the blood-brain barrier and accumulate in tumorous tissues. PMID:27386761

Ecotoxicity of nanoscale zero-valent iron particles – a review

Directory of Open Access Journals (Sweden)

José Tomás Albergaria

2013-11-01

Full Text Available The use of nanoscale zero-valent iron particles (nZVIs in the environmental remediation of water and soil is increasing. This increase is related to the higher reactivity and mobility of nZVIs compared with that of macro- or micro-sized iron particles. The introduction of nZVIs into the environment raises concerns related to their fate and effect on aquatic and terrestrial biota. Knowledge of these issues will allow a better understanding not only of the remediation process but also of the long-term effects and impact of nZVIs on ecosystems, leading to a safer and more efficient application of these particles. This paper presents the current state of play concerning the toxic effects of nZVIs on organisms at different stages of the food chain. The majority of studies show that nZVIs have a negative impact on bacteria, aquatic invertebrates, such as Daphnia mag-na, terrestrial organisms, such as Eisenia fetida, and seed germination. However, the number of published studies related to this issue is clearly insufficient. This reinforces the need for further research in order to specify the toxic concentrations of nZVIs that affect the most important target organisms. Furthermore, an evaluation of the effects of the coating of nanoparticles should also be pursued

PREPARATIONS AND APPLICATION OF METAL NANOPARTICLES

Directory of Open Access Journals (Sweden)

Adlim Adlim

2010-06-01

Full Text Available Terminology of metal nanoparticles, the uniqueness properties in terms of the surface atom, the quantum dot, and the magnetism are described. The further elaboration was on the synthesis of nanoparticles. Applications of metal nanoparticles in electronic, ceramic medical and catalysis were overviewed. The bibliography includes 81 references with 99% are journal articles.   Keywords: metal nanoparticles

PREPARATIONS AND APPLICATION OF METAL NANOPARTICLES

OpenAIRE

Adlim, Adlim

2010-01-01

Terminology of metal nanoparticles, the uniqueness properties in terms of the surface atom, the quantum dot, and the magnetism are described. The further elaboration was on the synthesis of nanoparticles. Applications of metal nanoparticles in electronic, ceramic medical and catalysis were overviewed. The bibliography includes 81 references with 99% are journal articles.   Keywords: metal nanoparticles

Study on degradation of nitrobenzene in groundwater using emulsified nano-zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Dong, Jun, E-mail: dongjun@jlu.edu.cn; Wen, Chunyu, E-mail: 13756014702@163.com; Liu, Dengfeng, E-mail: 862337789@qq.com [Jilin University, College of Environment and Resources (China); Zhang, Wenjing, E-mail: zhangwj@caep.org.cn [Chinese Academy for Environmental Planning (CAEP) (China); Li, Jintong, E-mail: 1535448369@qq.com; Jiang, Hanjie, E-mail: 1932639992@qq.com; Qin, Chongwei, E-mail: 476158689@qq.com; Hong, Mei, E-mail: hongmei@jlu.edu.cn [Jilin University, College of Environment and Resources (China)

2015-01-15

Emulsified nano-zero-valent iron (EZVI) is a modified form of bare nanoiron with improved transportability and targetability for the remediation of organic-solvents polluted soil and groundwater. In this work, EZVI (50–150 nm) was prepared by coating an emulsified vegetable oil membrane on the surface of Fe nanoparticles. EZVI was well-dispersed and less aggregation was observed. Batch experiments were conducted in anaerobic conditions to investigate the kinetics of nitrobenzene reduction by EZVI and the influences of oil concentration, initial iron content, and initial pH. Results indicated that the kinetics of nitrobenzene reduction by EZVI followed a pseudo-first-order kinetics. The observed rate constant of nitrobenzene is 0.0942 min{sup −1}. The oil concentration of 1 and 2 % tended to be preferred concentrations. The rate of nitrobenzene degradation and aniline formation increased with increasing iron content. The low pH is favorable to the nitrobenzene reduction by EZVI.

Synthesis, spectral characterization and redox properties of iron (II ...

Indian Academy of Sciences (India)

Unknown

Arylazoheterocycles and their chemistry of transition and non-transition metals have been explored for more than two decades.1 Owing to their pH-response, photoactivity, light electron communication, stabilization of low valent metal oxidation state, exhibition of serial redox states of complexes, isolation of anion radicals, ...

Biodegradable surfactant stabilized nanoscale zero-valent iron for in situ treatment of vinyl chloride and 1,2-dichloroethane

International Nuclear Information System (INIS)

Wei, Yu-Ting; Wu, Shian-chee; Yang, Shi-Wei; Che, Choi-Hong; Lien, Hsing-Lung; Huang, De-Huang

2012-01-01

Highlights: ► Biodegradable surfactant stabilized nanoscale zero-valent iron (NZVI) is tested. ► Vinyl chloride and 1,2-dichloroethane are remediated by NZVI in the field. ► Multiple functions of biodegradable surfactants are confirmed. ► Biodegradable surfactants stabilize NZVI and facilitate the bioremediation. ► NZVI creates reducing conditions beneficial to an anaerobic bioremediation. - Abstract: Nanoscale zero-valent iron (NZVI) stabilized with dispersants is a promising technology for the remediation of contaminated groundwater. In this study, we demonstrated the use of biodegradable surfactant stabilized NZVI slurry for successful treatment of vinyl chloride (VC) and 1,2-dichloroethane (1,2-DCA) in a contaminated site in Taiwan. The biodegradable surfactant stabilized NZVI was coated with palladium and synthesized on-site. From monitoring the iron concentration breakthrough and distribution, it was found that the stabilized NZVI is capable of transporting in the aquifer at the test plot (200 m 2 ). VC was effectively degraded by NZVI while the 1,2-DCA degradation was relatively sluggish during the 3-month field test. Nevertheless, as 1,2-DCA is known to resist abiotic reduction by NZVI, the observation of 1,2-DCA degradation and hydrocarbon production suggested a bioremediation took place. ORP and pH results revealed that a reducing condition was achieved at the testing area facilitating the biodegradation of chlorinated organic hydrocarbons. The bioremediation may be attributed to the production of hydrogen gas as electron donor from the corrosion of NZVI in the presence of water or the added biodegradable surfactant serving as the carbon source as well as electron donor to stimulate microbial growth.

Effectiveness of the 23-valent polysaccharide pneumococcal vaccine against invasive pneumococcal disease in people 60 years or older

Directory of Open Access Journals (Sweden)

Salsench Elisabet

2010-03-01

Full Text Available Abstract Background The 23-valent polysaccharide pneumococcal vaccine (PPV is currently recommended in elderly and high-risk adults. However, its efficacy in preventing pneumococcal infections remains controversial. This study assessed the clinical effectiveness of vaccination against invasive pneumococcal disease (IPD among people over 60 years. Methods Population-based case-control study that included 88 case patients over 60 years-old with a laboratory-confirmed IPD (bacteraemic pneumonia, meningitis or sepsis and 176 outpatient control subjects who were matched by primary care centre, age, sex and risk stratum. Adjusted odds ratios (ORs for vaccination were calculated using conditional logistic regression, controlling for underlying conditions. Vaccine effectiveness was estimated as (1 - OR ×100. Results Pneumococcal vaccination rate was significantly lower in cases than in control subjects (38.6% vs 59.1%; p = 0.002. The adjusted vaccine effectiveness was 72% (OR: 0.28; 95% CI: 0.15-0.54 against all IPD and 77% (OR: 0.23; 95% CI: 0.08-0.60 against vaccine-type IPD. Vaccination was significantly effective against all IPD in both age groups: 60-79 years-old (OR 0.32; 95% CI: 0.14-0.74 and people 80 years or older (OR: 0.29; 95% CI: 0.09-0.91. Vaccination appears significantly effective as for high-risk immunocompetent subjects (OR: 0.29; 95% CI: 0.11-0.79 as well as for immunocompromised subjects (OR: 0.12; 95% CI: 0.03-0.53. Conclusion These findings confirm the effectiveness of the 23-valent PPV against IPD, and they also support the benefit of vaccination in preventing invasive infections among high-risk and older people.

Immunogenicity and safety of 13-valent pneumococcal conjugate vaccine in Mexico

Directory of Open Access Journals (Sweden)

Maricruz Gutiérrez Brito

2013-06-01

Full Text Available OBJECTIVE: To assess the safety and immune responses induced by a 13-valent pneumococcal conjugate vaccine (PCV13 after immunization of infants in Mexico. METHODS: PCV13 was given with other routine childhood vaccinations to 225 infants in Mexico at ages 2, 4, 6, and 12 months. RESULTS: The proportions of subjects achieving immunoglobulin G (IgG concentrations ≥0.35 µg/mL after the infant series and toddler dose were ≥93.1% and ≥96.7%, respectively, for all 13 serotypes. The serotype-specific pneumococcal IgG geometric mean concentrations after the infant series and toddler dose ranged from 1.18 to 9.13 µg/mL and from 1.62 to 15.41 µg/mL, respectively. The most common local reaction and systemic event after each dose were tenderness and irritability, respectively. Most fever was mild; no fever >40.0°C (i.e., severe was reported. One subject withdrew because of Kawasaki disease 5 days after the first dose of vaccines, but this condition was not considered related to PCV13. CONCLUSIONS: Overall, PCV13 administered with routine pediatric vaccines was immunogenic and safe in healthy infants in Mexico.

Applications of Fractional q-Calculus to Certain Subclass of Analytic p-Valent Functions with Negative Coefficients

Directory of Open Access Journals (Sweden)

Ben Wongsaijai

2015-01-01

Full Text Available By making use of the concept of fractional q-calculus, we firstly define q-extension of the generalization of the generalized Al-Oboudi differential operator. Then, we introduce new class of q-analogue of p-valently closed-to-convex function, and, consequently, new class by means of this new general differential operator. Our main purpose is to determine the general properties on such class and geometric properties for functions belonging to this class with negative coefficient. Further, the q-extension of interesting properties, such as distortion inequalities, inclusion relations, extreme points, radii of generalized starlikeness, convexity and close-to-convexity, quasi-Hadamard properties, and invariant properties, is obtained. Finally, we briefly indicate the relevant connections of our presented results to the former results.

Removal of basic dye from aqueous solutions using nano scale zero valent iron (NZVI) as adsorbent

International Nuclear Information System (INIS)

Khan, M. S.; Ahmad, A.; Bangash, F. K.; Shah, S. S.; Khan, P.

2013-01-01

Nano scale zero valent iron (NZVI) was synthesized and tested for the purification of waste water contaminated by the organic pollutants. In the present study removal of basic blue 3 dye was investigated by NZVI adsorbent. NZVI adsorbent was prepared in the presence of N/sub 2/ gas atmosphere by sodium boro- hydrate (NaHB/sub 4/) reduction method. The particle size of the prepared adsorbent was approximately in the range of 1 x 10/sup -2/nm to 2 x 10/sup -2/nm. The adsorption of basic blue 3 dyes was confirmed with various parameters such as ionic strength, contact time and initial dye concentrations. The experiments were carried out in a batch mode technique. The surface morphology was studied by SEM analysis technique. (author)

Simultaneous adsorption and degradation of Zn(2+) and Cu (2+) from wastewaters using nanoscale zero-valent iron impregnated with clays.

Science.gov (United States)

Shi, Li-Na; Zhou, Yan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravi

2013-06-01

Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu(2+) and Zn(2+) from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu(2+) and Zn(2+) from a aqueous solution containing a 100 mg/l of Cu(2+) and Zn(2+), where 92.9 % Cu(2+) and 58.3 % Zn(2+) were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu(2+) and Zn(2+). A kinetics study indicated that removing Cu(2+) and Zn(2+) with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu(2+)and Zn(2+) on bentonite and the degradation of Cu(2+)and Zn(2+) by nZVI on the bentonite. However, Cu(2+) removal by B-nZVI was reduced rather than adsorption, while Zn(2+) removal was main adsorption. Finally, Cu(2+), Zn(2+), Ni(2+), Pb(2+) and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.

Application of Recycled Zero-Valent Iron Nanoparticle to the Treatment of Wastewater Containing Nitrobenzene

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Heon Lee

2015-01-01

Full Text Available Zero-valent iron (ZVI was synthesized using iron oxide, a byproduct of pickling line at a steel work. ZVI with a mean particle size of 500 nm was synthesized. The reaction activity of the synthesized ZVI was much higher than commercial ZVI. When applied to the decomposition of nitrobenzene (NB, the ZVI particles underwent corrosion and passivation oxide film formation, resulting in particle size decrease. The NB decomposition rate increased with increasing ZVI dosage level and with decreasing pH. The solution pH increased monotonously with increasing reaction duration, whereas the aniline concentration showed a maximum at 50 min. Based on the GC/MS analysis, NB is presumed to be reduced into aniline via reductive intermediates such as azobenzene and azoxybenzene. When combined with a subsequent biological process, the synthesized ZVI will be able to decompose NB in wastewater effectively.

CADDIS Volume 2. Sources, Stressors and Responses: Metals - Point Sources from Industry

Science.gov (United States)

Introduction to the metals module, when to list metals as a candidate cause, ways to measure metals, simple and detailed conceptual diagrams for metals, metals module references and literature reviews.

CADDIS Volume 2. Sources, Stressors and Responses: Metals - Detailed Conceptual Model Diagram

Science.gov (United States)

Introduction to the metals module, when to list metals as a candidate cause, ways to measure metals, simple and detailed conceptual diagrams for metals, metals module references and literature reviews.

CADDIS Volume 2. Sources, Stressors and Responses: Metals - Simple Conceptual Model Diagram

Science.gov (United States)

Introduction to the metals module, when to list metals as a candidate cause, ways to measure metals, simple and detailed conceptual diagrams for metals, metals module references and literature reviews.

Baseline metal concentrations in Paramoera walkeri from East Antarctica

International Nuclear Information System (INIS)

Palmer, Anne S. . E-mail Anne.Palmer@utas.edu.au; Snape, Ian; Stark, Jonathan S.; Johnstone, Glenn J.; Townsend, Ashley T.

2006-01-01

Remediation of the Thala Valley waste disposal site near Casey Station, East Antarctica was conducted in the austral summer of 2003/2004. Biomonitoring of the adjacent marine environment was undertaken using the gammaridean amphipod Paramoera walkeri as a sentinel species [Stark, J.S., Johnstone, G.J., Palmer, A.S., Snape, I., Larner, B.L., Riddle, M.J., in press, doi:10.1016/j.marpolbul.2006.05.020. Monitoring the remediation of a near shore waste disposal site in Antarctica using the amphipod Paramoera walkeri and diffusive gradients in thin films (DGTs). Marine Pollution Bulletin and references therein]. Determination of uptake of metals and hypothesis testing for differences that could be attributed to contamination required the establishment of baseline metal concentrations in P. walkeri. Baseline metal concentrations from two reference locations in the Windmill Islands are presented here. P. walkeri was a found to be a sensitive bioaccumulating organism that recorded spatial and temporal variability at the reference sites. Measurement of metals in P. walkeri required the development of a simple digestion procedure that used concentrated nitric acid. For the first time, rare earth metals were determined with additional clean procedures required to measure ultra low concentrations using magnetic sector ICP-MS. Certified and in-house reference materials were employed to ensure method reliability

Cellulose nanocrystal zero-valent iron nanocomposites for groundwater remediation†

Science.gov (United States)

Bossa, Nathan; Carpenter, Alexis Wells; Kumar, Naresh; de Lannoy, Charles-François

2018-01-01

Zero-valent iron nanoparticles (nano-ZVIs) have been widely studied for in situ remediation of groundwater and other environmental matrices. Nano-ZVI particle mobility and reactivity are still the main impediments in achieving efficient in situ groundwater remediation. Compared to the nano-ZVI “coating” strategy, nano-ZVI stabilization on supporting material allows direct contact with the contaminant, reduces the electron path from the nano-ZVI to the target contaminant and increases nano-ZVI reactivity. Herein, we report the synthesis of nano-ZVI stabilized by cellulose nanocrystal (CNC) rigid nanomaterials (CNC-nano-ZVI; Fe/CNC = 1 w/w) with two different CNC functional surfaces (–OH and –COOH) using a classic sodium borohydride synthesis pathway. The final nanocomposites were thoroughly characterized and the reactivity of CNC-nano-ZVIs was assessed by their methyl orange (MO) dye degradation potential. The mobility of nanocomposites was determined in (sand/glass bead) porous media by utilizing a series of flowthrough transport column experiments. The synthesized CNC-nano-ZVI provided a stable colloidal suspension and demonstrated high mobility in porous media with an attachment efficiency (α) value of less than 0.23. In addition, reactivity toward MO increased up to 25% compared to bare ZVI. The use of CNC as a delivery vehicle shows promising potential to further improve the capability and applicability of nano-ZVI for in situ groundwater remediation and can spur advancements in CNC-based nanocomposites for their application in environmental remediation. PMID:29725541

Heavy metals in reindeer and their forage plants

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O. Eriksson

1990-09-01

Full Text Available An attempt was made to assess the level of heavy metal transfer from forage plants to reindeer (Rangifer tarandus L. in an area in northern Lapland affected from dust from an open pit copper mine. Botanical analyses of rumen contents from reindeer provided information about the main plant species in the diet. Representative plant material was collected from sample plots within an 8 km radius from the central part of the mine and from a reference area situated about 200 km upwind of the mining site. The following plant species were analysed: Bryoria jremontii, Br. juscescens, Cladina rangiferina, Equisetum fluviatile, Descbampsiaflexuosa, Eriopborum vaginatum, Salix glauca, Salix pbylicifolia, Betula nana, and Vaccini-um myrtillus. The greatest difference between metal concentrations in the plants collected from dust contaminated area and from the reference area was found in lichens. Copper is the main metallic component of the ore and was found in higher concentrations in lichens coming from the area around the mine than in lichens from the reference area. Smaller differences were found in vascular plants. Dust particles, remaining on outer surfaces after snow smelt contributed to a limited extent to the metal contents. Species—specific accumulation of metals was observed in some plants. The uptake of lead and cadmium in some vascular plants was somewhat higher in the reference area compared with plants growing in the perifery of the mining center, probably due to the metal concentrations in the bedrock. Organ material (liver and kidney was collected from reindeer in both areas. No noticable effect on metal concentrations in the liver of the reindeer were found. Although the lead, cadmium and copper concentrations were higher in the organs collected from animals in the reference area than in those from the mining area, the levels were still below the concentrations regarded as harmful for the animals from toxicological point of view. The

Synergetic treatment of uranium-bearing waste water with sulfate reducing bacteria and zero-valent iron

International Nuclear Information System (INIS)

Zhou Quanyu; Tan Kaixuan; Zeng Sheng; Liu Dong

2009-01-01

The treatment of uranium-bearing wastewater from uranium mine and using microorganism to treat wastewater were paid much attention to environmental researchers. Based on column experiments, we investigated the potential using sulfate reducing bacteria (SRB) and zero-valent iron (ZVI) to synergetic treat contamination in wastewater such as sulfate, uranium, etc. SRB+ZVI can effectively remove contamination U(VI) and SO 4 2- in wastewater. The removal rate is 99.4% and 86.2% for U(VI) and SO 4 2- , respectively. The pH of wastewater can be basified to neutral. U(VI) and SO 4 2- as electron acceptor of sulfate reducing bacteria are removed by biological reduction. The corrosion of ZVI is benefit to enhance the pH of wastewater, forms anaerobic reducing environment, strengthens survival and metabolism reaction of SRB, and plays a synergetic enhancement. (authors)

Variability in carbon isotope fractionation of trichloroethene during degradation by persulfate activated with zero-valent iron: Effects of inorganic anions

Energy Technology Data Exchange (ETDEWEB)

Liu, Yunde [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Zhou, Aiguo, E-mail: aiguozhou@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gan, Yiqun; Li, Xiaoqian [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

2016-04-01

Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from − 3.4 ± 0.3 to − 4.3 ± 0.3 ‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from − 7.0 ± 0.4 to − 13.6 ± 1.2 ‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO{sub 4}·{sup −}). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). - Highlights: • Significant C isotope fractionation for TCE degradation by Fe{sup 0} activated persulfate. • The enrichment factors was independent of Fe{sup 0}, SO{sub 4}{sup 2−}, or HCO{sub 3}{sup −} concentration. • Cl{sup −} significantly influenced the carbon isotope fractionation.

Variability in carbon isotope fractionation of trichloroethene during degradation by persulfate activated with zero-valent iron: Effects of inorganic anions

International Nuclear Information System (INIS)

Liu, Yunde; Zhou, Aiguo; Gan, Yiqun; Li, Xiaoqian

2016-01-01

Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from − 3.4 ± 0.3 to − 4.3 ± 0.3 ‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from − 7.0 ± 0.4 to − 13.6 ± 1.2 ‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO_4·"−). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). - Highlights: • Significant C isotope fractionation for TCE degradation by Fe"0 activated persulfate. • The enrichment factors was independent of Fe"0, SO_4"2"−, or HCO_3"− concentration. • Cl"− significantly influenced the carbon isotope fractionation.

Investigation of washing and storage strategy on aging Of Mg-aminoclay (MgAC) coated nanoscale zero-valent iron (nZVI) particles

DEFF Research Database (Denmark)

Hwang, Yuhoon; Lee, Young-Chul; Mines, Paul D.

2014-01-01

The tendency towards agglomeration and oxidation of nanoscale zero-valent iron (nZVI) particles limits its application for in situ groundwater and soil remediation. Although the effect of surface coatings on nanoparticle stabilization has been commonly practiced, the effect of preparation...... correlations (r2 > 0.95, p one another. Pre-storage washing, followed by addition of MgAC, exhibits high stability as pre-storage washing, as well as high reactivity as post-storage washing. Here, it is found that the proper washing procedure is crucial in coated nZVI preparation...

Nanoscale zero-valent iron (nZVI) synthesis in a Mg-aminoclay solution exhibits increased stability and reactivity for reductive decontamination

DEFF Research Database (Denmark)

Hwang, Yuhoon; Lee, Young-Chul; Mines, Paul D.

2014-01-01

Nanoscale zero-valent iron (nZVI) has often been explored as a reductant for detoxification of pollutants in environmental clean-ups. Despite the large surface area and superior reactivity of nZVI, its limited stability is a major obstacle in applying nZVI for in situ subsurface remediation, e......ZVI particles with higher crystallinity were produced. Stability of nZVI particles were evaluated using a sedimentation test and a dynamic light scattering technique. The characteristic time increased from 6.71 to 83.8 min, and particle (aggregate diameter) size decreased from 5132 to 186 nm with increasing...

Theoretical investigation of structure and stability of molecules and ions HAO2, HAS2, HSAO and HOAS with 16 valent electrons (A = B, Al, C+, Si+)

International Nuclear Information System (INIS)

Zyubina, T.S.; Charkin, O.P.

1991-01-01

Using several basic sets and taking into consideration electron correlation in the framework of MP3 approximation, non-empiric calculations of the structure and stability of HAO 2 , HAS 2 , HOAS, HSAO molecules and ions with 16 valent electrons (A = B, Al, C + , Si + ) were made. Similarity of OAS, AO 2 , AS 2 (A = B - , Al - , C, Si) molecules and ions to proton was ascertained

Immunogenicity and persistence of the 13-valent Pneumococcal Conjugate Vaccine (PCV13) in patients with untreated Smoldering Multiple Myeloma (SMM): A pilot study.

Science.gov (United States)

Bahuaud, Mathilde; Bodilis, Hélène; Malphettes, Marion; Maugard Landre, Anaïs; Matondo, Caroline; Bouscary, Didier; Batteux, Frédéric; Launay, Odile; Fermand, Jean-Paul

2017-11-01

Smoldering multiple myeloma (SMM) is an asymptomatic clonal plasma cell disorder that frequently progress to multiple myeloma (MM), a disease at high risk of pneumococcal infections. Moreover, if the polysaccharide vaccine is poorly immunogenic in MM, the 13-valent conjugated vaccine has never been tested in clonal plasma cell disorders. We evaluated its immunogenicity for 7 serotypes in 20 patients ≥ 50 years of age with smoldering multiple myeloma (SMM) pre and post routine-vaccination with PCV13. Concentrations of IgG specific for 7 serotypes were measured at baseline, 1, 6, and 12 months after vaccination by standardized ELISA and an Opsonophagocytic Assay (OPA). The primary endpoint was the proportion of patients responding to at least 5 of the 7 serotypes by ELISA at one month. At 1 month post vaccination, 12 patients (60%) were responders by ELISA, among whom 8 were also responders by OPA. At 6 months, 6 (30% of total) of the 12 responders had persistent immunity, and only 2 (10% of total) at 12 months. These results suggested a partial response in this population and a rapid decrease in antibody levels in the first months of vaccination. Although one injection of the 13-valent pneumococcal conjugate vaccine is immunogenic in some patients with SMM, the response is transient. Repeated injections are likely to be needed for effective and sustained protection.

Micro-electrolysis of Cr (VI) in the nanoscale zero-valent iron loaded activated carbon.

Science.gov (United States)

Wu, Limei; Liao, Libing; Lv, Guocheng; Qin, Faxiang; He, Yujuan; Wang, Xiaoyu

2013-06-15

In this paper we prepared a novel material of activated carbon/nanoscale zero-valent iron (C-Fe(0)) composite. The C-Fe(0) was proved to possess large specific surface area and outstanding reducibility that result in the rapid and stable reaction with Cr (VI). The prepared composite has been examined in detail in terms of the influence of solution pH, concentration and reaction time in the Cr (VI) removal experiments. The results showed that the C-Fe(0) formed a micro-electrolysis which dominated the reaction rate. The Micro-electrolysis reaches equilibrium is ten minutes. Its reaction rate is ten times higher than that of traditional adsorption reaction, and the removal rate of Cr reaches up to 99.5%. By analyzing the obtained profiles from the cyclic voltammetry, PXRD and XPS, we demonstrate that the Cr (VI) is reduced to insoluble Cr (III) compound in the reaction. Copyright © 2013 Elsevier B.V. All rights reserved.

Removal of Acid Red 18 dye from Aqueous Solutions Using Nanoscale Zero-Valent Iron

Directory of Open Access Journals (Sweden)

Ahmad Reza Yari

2015-08-01

Full Text Available Background and Purpose:Organic dyes with a complex structure are often toxic, carcinogenic, mutagenic, non-biodegradation and stable in the environment and if released to the environment without treatment can endanger the environment and human health. The aim was to evaluate the performance nanoscalezero-valent iron (NZVI in the removal of dye acid red 18 (AR18 from aqueous solutions. Materials and Methods:This study was conducted at the laboratory scale. In this study, the removal efficiency of AR18 from a synthetic solution by NZVI was investigated. As well as the effect of solution pH, dye concentration, the concentration of NZVI and contact time in decolorization efficiency was investigated. Results:The results show that in pH = 3, contact time of 80 minutes, dye concentration of 25 mg/l and concentration of NZVI of 2 g/l, the removal efficiency was about 94%. Conclusion:According to the results of experiments, NZVI has high efficiency in removal of AR18 from aqueous solution.

Influence of a step-change in metal exposure (Cd, Cu, Zn) on metal accumulation and subcellular partitioning in a freshwater bivalve, Pyganodon grandis: A long-term transplantation experiment between lakes with contrasting ambient metal levels

Energy Technology Data Exchange (ETDEWEB)

Cooper, Sophie [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada); Bonneris, Emmanuelle [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada) and Bayer S.A.S., Bayer CropScience, 16 Rue Jean-Marie Leclair, CP 90106, F 69266 Lyon Cedex 09 (France); Michaud, Annick [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada) and Direction des Évaluations environnementales, Ministère du Développement durable, de l’Environnement et des Parcs, 675, boul. René-Lévesque Est, 6e étage, Québec, QC G1R 5V7 (Canada); Pinel-Alloul, Bernadette [Groupe de Recherche Interuniversitaire en Limnologie et Environnement Aquatique (GRIL), Département de Sciences Biologiques, Université de Montréal, C.P. 6128, Montréal, QC H3C 3J7 (Canada); Campbell, Peter G.C., E-mail: peter.campbell@ete.inrs.ca [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada)

2013-05-15

Highlights: ? We transferred freshwater bivalves from a reference lake to a Cd and Zn contaminated lake. ? Changes in metal accumulation and subcellular partitioning were followed over time (up to 860 d). ? Metal detoxification strategies differed between target organs (gills vs. digestive gland). ? The ability to handle Cd is inherent in P. grandis, not a trait acquired after long-term adaptation. -- Abstract: The objective of the present field experiment was to identify detoxification responses in the gills and digestive gland of a freshwater unionid bivalve, Pyganodon grandis, subjected to a step-change in metal exposure. Adult bivalves were transferred from a reference site (Lake Opasatica) and a metal-contaminated lake (Lake Héva) to a second contaminated lake (Lake Vaudray) in northwestern Quebec, Canada. Changes in organ metal concentrations, in the subcellular distribution of metals and in metallothionein concentrations were followed over time (t = 0, 132, (400) and 860 days). At each collection time and for each bivalve, the gills and digestive gland were excised and gently homogenized; six sub-cellular fractions were separated by differential centrifugation and analyzed for their Cd, Cu and Zn content, and metallothionein was quantified independently. Metal detoxification strategies were shown to differ between target organs: in the gills, incoming metals were sequestered largely in the granules, whereas in the digestive gland the same metals primarily accumulated in the cytosol, in the metallothionein-like protein fraction. These metal-handling strategies, as employed by the metal-naïve bivalves originating in the reference lake, closely resemble those identified in free-living P. grandis chronically exposed in the metal-contaminated lake, suggesting that the ability to handle incoming metals (Cd in particular) is inherent in P. grandis and is not a trait acquired after long-term adaptation of the bivalve to metal-contaminated environments. The

Ecofriendly Synthesis of nano Zero Valent Iron from Banana Peel Extract

Science.gov (United States)

Sunardi; Ashadi; Budi Rahardjo, Sentot; Inayati

2017-01-01

In this study, nano Zero Valent Iron (nZVI) were synthesized from banana peel extract (BPE) and ferrous sulfate. During the synthesis of nZVI both the precursor and the reducing agent were mixed in a clean sterilized flask in 1:1 proportion. For the reduction of Fe ions, 5 ml of filtered BPE was mixed to 5 ml of freshly prepared 0.001 M - 0.005 M aqueous of FeSO4 solution with constant stirring at room temperature. Within a particular time change in colour from brown to black color obtained by nanoparticles synthesis. A systematic characterization of nZVI was performed using UV-Vis. UV-visible absorption is used to investigate SPR. Characteristic surface plasmon absorption band was observed at 210 nm for the black colored nZVI synthesized from 0.001-0.005 M ferrous sulfate with BPE concentration 5 ml. It has been found that the optimum concentration for the synthesis of nZVI is 0.001M Fe2+ ions. There is small decrease in the intensity of SPR band from 0.001 to 0.005 M. The characterization size of nZVI was performed using TEM. The result shows that formation of particles size of nZVI was more 100 nm.

Ecofriendly Synthesis of nano Zero Valent Iron from Banana Peel Extract

International Nuclear Information System (INIS)

Sunardi; Ashadi; Rahardjo, Sentot Budi; Inayati

2017-01-01

In this study, nano Zero Valent Iron (nZVI) were synthesized from banana peel extract (BPE) and ferrous sulfate. During the synthesis of nZVI both the precursor and the reducing agent were mixed in a clean sterilized flask in 1:1 proportion. For the reduction of Fe ions, 5 ml of filtered BPE was mixed to 5 ml of freshly prepared 0.001 M – 0.005 M aqueous of FeSO 4 solution with constant stirring at room temperature. Within a particular time change in colour from brown to black color obtained by nanoparticles synthesis. A systematic characterization of nZVI was performed using UV-Vis. UV–visible absorption is used to investigate SPR. Characteristic surface plasmon absorption band was observed at 210 nm for the black colored nZVI synthesized from 0.001–0.005 M ferrous sulfate with BPE concentration 5 ml. It has been found that the optimum concentration for the synthesis of nZVI is 0.001M Fe 2+ ions. There is small decrease in the intensity of SPR band from 0.001 to 0.005 M. The characterization size of nZVI was performed using TEM. The result shows that formation of particles size of nZVI was more 100 nm. (paper)

Study on the concentration and seasonal variation of inorganic elements in 35 species of marine algae

DEFF Research Database (Denmark)

Hou, Xiaolin; Yan, X.J.

1998-01-01

The concentrations of five major and 28 trace elements in 35 marine algae collected along the coast of China were determined by instrumental neutron activation analysis. The concentrations of halogens, rare earth elements and many transition metal elements in marine algae are remarkably higher than...... those in terrestrial plants. The concentration factors for 31 elements in all collected algae were calculated, those for tri- and tetra-valent elements were higher than those of the mono- and di-valent elements in marine algae. The biogeochemical characteristics of inorganic elements in marine algae...

Tres lecciones de tinieblas, de José Ángel Valente: naturaleza musical, claves de poética e implicaciones simbólicas

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Francisco Javier Escobar Borrego

2012-06-01

Full Text Available El presente artículo ofrece un estudio circunscrito a la caracterización musical de Tres lecciones de tinieblas (1980, de José Ángel Valente (1929-2000. Para ello, se parte, en primer lugar, del análisis de las claves de poética que ofrece el escritor en distintos textos (entrevistas, ensayos, discursos, diario … para, con posterioridad, identificar las fuentes de dicho poemario, ya sean musicales –desde el canto gregoriano hasta Webern, Boulez o Schenker–, literarias (Gonzalo de Berceo, filosóficas (Miguel de Molinos, etc. En el conjunto de modelos presentado sobresale, en particular, la asimilación por parte de Valente del género de las Leçons des Ténèbres –sobre todo, Couperin y Charpentier–, así como de la tradición áurea española, con ecos de Tomás Luis de Victoria, Quevedo y sus Lágrimas de Hieremías castellanas, la «música silente» de San Juan de la Cruz o la «poesía musical» de Góngora, entre otros señeros referentes. Por último, dada la compleja naturaleza genérica de Tres lecciones, se presta especial atención, en fin, tanto al simbolismo pitagórico como a las propiedades musicales de las letras-números para concluir con unas notas sobre la poética del fragmento.

Zero-valent iron/iron oxide-oxyhydroxide/graphene as a magnetic sorbent for the enrichment of polychlorinated biphenyls, polyaromatic hydrocarbons and phthalates prior to gas chromatography-mass spectrometry.

Science.gov (United States)

Karamani, Anna A; Douvalis, Alexios P; Stalikas, Constantine D

2013-01-04

A composite magnetic material consisting of zero-valent iron, iron oxide-oxyhydroxide and graphene was synthesized and used successfully as a sorbent for the micro solid-phase extraction of PAHs, PCBs and phthalic acid esters. The components endow the composite with multiple characteristics such as adsorption capability and facile removal due to its magnetic properties. Due to the π-π electrostatic stacking property of graphene, the high specific surface area and the adsorption capability of both components, the resulting black flaky Fe(0)/iron oxide-oxyhydroxide/graphene composite showed high extraction efficiency for the target analytes from water samples. Compared with the neat graphene, the composite material has improved properties in terms of microextraction capabilities as both the hydrophobic graphene and zero-valent iron participate in the adsorption of the hydrophobic molecules. The precision from the extraction of all three groups of compounds was lower than 7% and the recoveries were from 90 to 93% from a spiked lake water sample. The high recoveries in relation to the low final volume of the desorption solvent ensure high preconcentration efficiency and a promising sorbent for analytical applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Optimization of Reactive Blue 21 removal by Nanoscale Zero-Valent Iron using response surface methodology

Directory of Open Access Journals (Sweden)

Mahmood Reza Sohrabi

2016-07-01

Full Text Available Since Reactive Blue 21 (RB21 is one of the dye compounds which is harmful to human life, a simple and sensitive method to remove this pollutant from wastewater is using Nano Zero-Valent Iron (NZVI catalyst. In this paper, a Central Composite Rotatable Design (CCRD was employed for response surface modeling to optimize experimental conditions of the RB21 removal from aqueous solution. The significance and adequacy of the model were analyzed using analysis of variance (ANOVA. Four independent variables—including catalyst amount (0.1–0.9 g, pH (3.5–9.5, removal time (30–150 s and dye concentration (10–50 mg/L—were transformed to coded values and consequently second order quadratic model was built to predict the responses. The result showed that under optimized experimental conditions the removal of RB21 was over 95%.

Lifetime of the internal reference oxygen sensor

DEFF Research Database (Denmark)

Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels

2013-01-01

The internal reference oxygen sensor (IROS) based on a binary mixture of metal and its stoichiometric oxide is subject to leaks that result in consumption of the binary mixture. An IROS loses the functionality when the binary mixture is exhausted. Among the possible leak sources the electronic leak...

Use of Vegetable Fibers for PRB to Remove Heavy Metals from Contaminated Aquifers-Comparisons among Cabuya Fibers, Broom Fibers and ZVI.

Science.gov (United States)

Mayacela Rojas, Celia Margarita; Rivera Velásquez, María Fernanda; Tavolaro, Adalgisa; Molinari, Antonio; Fallico, Carmine

2017-06-24

The Zero Valent Iron (ZVI) is the material most commonly used for permeable reactive barriers (PRB). For technical and economic reasons, hoter reactive substances usable in alternative to ZVI are investigated. The present study takes into account a vegetable fibers, the cabuya, investigating its capacity to retain heavy metals. The capacity of the cabuya fibers to adsorb heavy metals was verified in laboratory, by batch and column tests. The batch tests were carried out with cabuya and ZVI, using copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb). The results obtained by the cabuya fibers showed a very high adsorption capacity of heavy metals and resulted very similar to those obtained for the broom fibers in a previous study. The high value of the absorption capacity of the cabuya fibers was also confirmed by the analogous comparison made with the results of the batch tests carried out with ZVI. Column tests, using copper, zinc and cadmium, allowed to determine for the cabuya fibers the maximum removal percentage of the heavy metals considered, the corresponding times and the time ranges of the release phase. For each metal considered, for a given length and three different times, the constant of degradation of cabuya fibers was determined, obtaining values very close to those reported for broom fibers. The scalar behavior of heavy metal removal percentage was verified. An electron microscope analysis allowed to compare, by SEM images, the characteristics of the cabuya and broom fibers. Finally, to investigate the chemical structure of cabuya and broom fibers, the FTIR technique was used, obtaining their respective infrared spectra.

Electrochemical depassivation of zero-valent iron for trichloroethene reduction

Energy Technology Data Exchange (ETDEWEB)

Chen, Liang [Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences, Beijing 100083 (China); Jin, Song [Department of Civil and Architectural Engineering, University of Wyoming, Laramie, WY 82071 (United States); Advanced Environmental Technologies, LLC, Fort Collins, CO 80524 (United States); Fallgren, Paul H. [Department of Civil Engineering, University of Colorado Denver, Denver, CO 80217 (United States); Swoboda-Colberg, Norbert G. [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States); Liu, Fei [Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences, Beijing 100083 (China); Colberg, Patricia J.S., E-mail: pczoo@uwyo.edu [Department of Civil and Architectural Engineering, University of Wyoming, Laramie, WY 82071 (United States)

2012-11-15

Highlights: Black-Right-Pointing-Pointer Electrical current may depassivate ZVI and restore its capacity to reduce TCE. Black-Right-Pointing-Pointer Electrical current may defer or even prevent surface oxidation of ZVI. Black-Right-Pointing-Pointer Electrical current coupled with ZVI achieves greater TCE reduction than ZVI alone. - Abstract: Permeable reactive barriers (PRBs) composed of zero-valent iron (ZVI) are susceptible to passivation, resulting in substantially decreased rates of chlorinated solvent removal over time. In this study, the application of low electrical direct current (DC) to restore the reductive capacity of passivated ZVI was examined. Electrical current was applied to a laboratory column reactor filled with a mixture of pre-passivated ZVI and sand. Variable voltage settings (0-12 V) were applied through two stainless steel electrodes placed at the ends of the reactor. While only partial restoration of the reductive capacity of the passivated ZVI was observed, higher rates of trichloroethene (TCE) removal were always obtained when current was applied, and the rates of TCE removal were roughly proportional to the voltage level. Although differences were observed between the rates and extent of TCE removal within the column, it is noteworthy that TCE removal was not restricted to that region of the column where the electrons entered (i.e., at the cathode). While complete 'depassivation' of ZVI may be difficult to achieve in practice, the application of DC demonstrated observable restoration of reactivity of the passivated ZVI. This study provides evidence that this approach may significantly extend the life of a ZVI PRB.

Electrochemical depassivation of zero-valent iron for trichloroethene reduction

International Nuclear Information System (INIS)

Chen, Liang; Jin, Song; Fallgren, Paul H.; Swoboda-Colberg, Norbert G.; Liu, Fei; Colberg, Patricia J.S.

2012-01-01

Highlights: ► Electrical current may depassivate ZVI and restore its capacity to reduce TCE. ► Electrical current may defer or even prevent surface oxidation of ZVI. ► Electrical current coupled with ZVI achieves greater TCE reduction than ZVI alone. - Abstract: Permeable reactive barriers (PRBs) composed of zero-valent iron (ZVI) are susceptible to passivation, resulting in substantially decreased rates of chlorinated solvent removal over time. In this study, the application of low electrical direct current (DC) to restore the reductive capacity of passivated ZVI was examined. Electrical current was applied to a laboratory column reactor filled with a mixture of pre-passivated ZVI and sand. Variable voltage settings (0–12 V) were applied through two stainless steel electrodes placed at the ends of the reactor. While only partial restoration of the reductive capacity of the passivated ZVI was observed, higher rates of trichloroethene (TCE) removal were always obtained when current was applied, and the rates of TCE removal were roughly proportional to the voltage level. Although differences were observed between the rates and extent of TCE removal within the column, it is noteworthy that TCE removal was not restricted to that region of the column where the electrons entered (i.e., at the cathode). While complete “depassivation” of ZVI may be difficult to achieve in practice, the application of DC demonstrated observable restoration of reactivity of the passivated ZVI. This study provides evidence that this approach may significantly extend the life of a ZVI PRB.

A green and efficient technology for the degradation of cellulosic materials: structure changes and enhanced enzymatic hydrolysis of natural cellulose pretreated by synergistic interaction of mechanical activation and metal salt.

Science.gov (United States)

Zhang, Yanjuan; Li, Qian; Su, Jianmei; Lin, Ye; Huang, Zuqiang; Lu, Yinghua; Sun, Guosong; Yang, Mei; Huang, Aimin; Hu, Huayu; Zhu, Yuanqin

2015-02-01

A new technology for the pretreatment of natural cellulose was developed, which combined mechanical activation (MA) and metal salt treatments in a stirring ball mill. Different valent metal nitrates were used to investigate the changes in degree of polymerization (DP) and crystallinity index (CrI) of cellulose after MA+metal salt (MAMS) pretreatment, and Al(NO3)3 showed better pretreatment effect than NaNO3 and Zn(NO3)2. The destruction of morphological structure of cellulose was mainly resulted from intense ball milling, and the comparative studies on the changes of DP and crystal structure of MA and MA+Al(NO3)3 pretreated cellulose samples showed a synergistic interaction of MA and Al(NO3)3 treatments with more effective changes of structural characteristics of MA+Al(NO3)3 pretreated cellulose and substantial increase of reducing sugar yield in enzymatic hydrolysis of cellulose. In addition, the results indicated that the presence of Al(NO3)3 had significant enhancement for the enzymatic hydrolysis of cellulose. Copyright © 2014 Elsevier Ltd. All rights reserved.

Positional reference system for ultraprecision machining

International Nuclear Information System (INIS)

Arnold, J.B.; Burleson, R.R.; Pardue, R.M.

1982-01-01

A stable positional reference system for use in improving the cutting tool-to-part contour position in numerical controlledmultiaxis metal turning machines is provided. The reference system employs a plurality of interferometers referenced to orthogonally disposed metering bars which are substantially isolated from machine strain induced position errors for monitoring the part and tool positions relative to the metering bars. A microprocessor-based control system is employed in conjunction with the plurality of position interferometers and part contour description data inputs to calculate error components for each axis of movement and output them to corresponding axis drives with appropriate scaling and error compensation. Real-time position control, operating in combination with the reference system, makes possible the positioning of the cutting points of a tool along a part locus with a substantially greater degree of accuracy than has been attained previously in the art by referencing and then monitoring only the tool motion relative to a reference position located on the machine base

Positional reference system for ultraprecision machining

Science.gov (United States)

Arnold, J.B.; Burleson, R.R.; Pardue, R.M.

1980-09-12

A stable positional reference system for use in improving the cutting tool-to-part contour position in numerical controlled-multiaxis metal turning machines is provided. The reference system employs a plurality of interferometers referenced to orthogonally disposed metering bars which are substantially isolated from machine strain induced position errors for monitoring the part and tool positions relative to the metering bars. A microprocessor-based control system is employed in conjunction with the plurality of positions interferometers and part contour description data input to calculate error components for each axis of movement and output them to corresponding axis driven with appropriate scaling and error compensation. Real-time position control, operating in combination with the reference system, makes possible the positioning of the cutting points of a tool along a part locus with a substantially greater degree of accuracy than has been attained previously in the art by referencing and then monitoring only the tool motion relative to a reference position located on the machine base.

‘The Eternal No-Return’: Melancholy and Deterritorialization in the Cántigas de Alén by José Ángel Valente

Directory of Open Access Journals (Sweden)

Margarita García Candeira

2013-10-01

Full Text Available The article explores Cántigas de alén, published in 1989 by José Ángel Valente, in light of the exiled and bilingual condition of its author. In this sense, the collection can be seen as a peculiar elegy for a part of Valente’s personal and authorial identity; its loss generates a melancholic pattern that encourages an impossible return. The premise of a Galician identity based in deterritorialization, in which a complex reformulation of saudade acquires a special relevance, is shaped by the precarious language.

Assessment of Pb (II Removal from Aqueous Solutions by Ascorbic Acid-stabilized Zero-valent Iron Nanoparticles Using Response Surface Methodology (RSM

Directory of Open Access Journals (Sweden)

Mohaddeseh Savasari

2017-07-01

Full Text Available The growing pollution of water resources and the limited availability of water supplies have led to a growing interest by researchers to develop novel methods of water remediation and reuse. One such method is the use of ascorbic acid-stabilized zero-valent iron nanoparticles (AAS-ZVIN for the removal of lead (Pb from aqueous solutions. Using zero-valent iron nanoparticles stabilized with acid ascorbic under aerobic conditions, the present study was conducted to assess the efficiency of Pb removal from aqueous solutions and its optimization by the response surface methodology (RSM. For this purpose, use was made of the central composite design and the response surface methodology with the four input variables of ASS- ZVIN dose (0.5, 1, and 2 g L-1, pH (2, 5, and 7, contact time (5, 20, and 60 min, and initial Pb concentration (5, 10, and 20 mg L-1 to determine the optimal conditions for the process. Numerical optimization revealed that the optimum conditions for Pb removal (97.93% included an ASS-ZVIN dose of 2 g L-1, an initial Pb (II concentration of 25 mg L-1, a contact time of 60 min, and an initial solution pH of 7. The results also imply that not only does ASS-ZVIN offer a good potential for the remediation of water bodies contaminated with Pb, given its high reactivity for Pb removal, but that  the RSM optimization process can be successfully employed for the optimization of the process in question.

Improved Internal Reference Oxygen Sensors Using Composite Oxides as Electrodes

DEFF Research Database (Denmark)

Hu, Qiang

The thesis describes the research on and development of an internal reference oxygen sensor (IROS). The IROS is potentiometric and uses the equilibrium pO2of the binary mixture of Ni/NiO as the reference pO2. The sensing electrode of the IROS are made from metallic Pt or the composite of (La0.75S...... the application of IROSes are provided. Based on the concepts and fundamentals of the IROS, internal reference sensors that detect other gas species such as hydrogen, chlorine and bromine may be developed.......The thesis describes the research on and development of an internal reference oxygen sensor (IROS). The IROS is potentiometric and uses the equilibrium pO2of the binary mixture of Ni/NiO as the reference pO2. The sensing electrode of the IROS are made from metallic Pt or the composite of (La0.75Sr0...... from 8YSZ is evaluated quantitatively and figures that may be used to design the depletion period of an IROS due to the electronic leak of 8YSZ are provided. One dimensional numerical simulations are performed to study the variation in cell voltage during the process of gas mixing, and the asymmetric...

Stabilization of ferroelectric properties in Hafnia and Zirconia

Energy Technology Data Exchange (ETDEWEB)

Kersch, Alfred [Univ. of Applied Sciences Munich (Germany). Modeling and Simulation Lab

2016-11-01

Experiments by our collaborators show that not only earth alkaline metals but also lanthanides and boron group metals are capable of inducing ferroelectric behavior in Hafnia. These dopants are known to form more complex defect structures due to their 3-valent nature. This requires further simulation. In some cases computationally more expensive density functionals will be required.

In situ characterization of cofacial Co(IV) centers in Co4O4 cubane: Modeling the high-valent active site in oxygen-evolving catalysts.

Science.gov (United States)

Brodsky, Casey N; Hadt, Ryan G; Hayes, Dugan; Reinhart, Benjamin J; Li, Nancy; Chen, Lin X; Nocera, Daniel G

2017-04-11

The Co 4 O 4 cubane is a representative structural model of oxidic cobalt oxygen-evolving catalysts (Co-OECs). The Co-OECs are active when residing at two oxidation levels above an all-Co(III) resting state. This doubly oxidized Co(IV) 2 state may be captured in a Co(III) 2 (IV) 2 cubane. We demonstrate that the Co(III) 2 (IV) 2 cubane may be electrochemically generated and the electronic properties of this unique high-valent state may be probed by in situ spectroscopy. Intervalence charge-transfer (IVCT) bands in the near-IR are observed for the Co(III) 2 (IV) 2 cubane, and spectroscopic analysis together with electrochemical kinetics measurements reveal a larger reorganization energy and a smaller electron transfer rate constant for the doubly versus singly oxidized cubane. Spectroelectrochemical X-ray absorption data further reveal systematic spectral changes with successive oxidations from the cubane resting state. Electronic structure calculations correlated to experimental data suggest that this state is best represented as a localized, antiferromagnetically coupled Co(IV) 2 dimer. The exchange coupling in the cofacial Co(IV) 2 site allows for parallels to be drawn between the electronic structure of the Co 4 O 4 cubane model system and the high-valent active site of the Co-OEC, with specific emphasis on the manifestation of a doubly oxidized Co(IV) 2 center on O-O bond formation.

Phytotoxicity of trace metals in spiked and field-contaminated soils: Linking soil-extractable metals with toxicity.

Science.gov (United States)

Hamels, Fanny; Malevé, Jasmina; Sonnet, Philippe; Kleja, Dan Berggren; Smolders, Erik

2014-11-01

Soil tests have been widely developed to predict trace metal uptake by plants. The prediction of metal toxicity, however, has rarely been tested. The present study was set up to compare 8 established soil tests for diagnosing phytotoxicity in contaminated soils. Nine soils contaminated with Zn or Cu by metal mining, smelting, or processing were collected. Uncontaminated reference soils with similar soil properties were sampled, and series of increasing contamination were created by mixing each with the corresponding soil. In addition, each reference soil was spiked with either ZnCl2 or CuCl2 at several concentrations. Total metal toxicity to barley seedling growth in the field-contaminated soils was up to 30 times lower than that in corresponding spiked soils. Total metal (aqua regia-soluble) toxicity thresholds of 50% effective concentrations (EC50) varied by factors up to 260 (Zn) or 6 (Cu) among soils. For Zn, variations in EC50 thresholds decreased as aqua regia > 0.43 M HNO3  > 0.05 M ethylenediamine tetraacetic acid (EDTA) > 1 M NH4 NO3  > cobaltihexamine > diffusive gradients in thin films (DGT) > 0.001 M CaCl2 , suggesting that the last extraction is the most robust phytotoxicity index for Zn. The EDTA extraction was the most robust for Cu-contaminated soils. The isotopically exchangeable fraction of the total soil metal in the field-contaminated soils markedly explained the lower toxicity compared with spiked soils. The isotope exchange method can be used to translate soil metal limits derived from soils spiked with metal salts to site-specific soil metal limits. © 2014 SETAC.

Evolution of nanoscale zero-valent iron (nZVI) in water: Microscopic and spectroscopic evidence on the formation of nano- and micro-structured iron oxides

Energy Technology Data Exchange (ETDEWEB)

Liu, Airong, E-mail: liuairong@tongji.edu.cn; Liu, Jing; Han, Jinhao; Zhang, Wei-xian, E-mail: zhangwx@tongji.edu.cn

2017-01-15

Highlights: • A comprehensive study of corrosion products for nZVI under both oxic and anoxic conditions is performed. • Under anoxic conditions, the oxidation products contain a mixture of wustite (FeO), goethite (α-FeOOH) and akaganeite (β-FeOOH). • Under oxic conditions, the final products are mainly crystalline lepidocrocite (γ-FeOOH) with acicular-shaped structures. • Morphological and structural evolution of nZVI under both oxic and anoxic conditions are substantially different. - Abstract: Knowledge on the transformation of nanoscale zero-valent iron (nZVI) in water is essential to predict its surface chemistry including surface charge, colloidal stability and aggregation, reduction and sorption of organic contaminants, heavy metal ions and other pollutants in the environment. In this work, transmission electronic microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy are applied to study the compositional and structural evolution of nZVI under oxic and anoxic conditions. Under anoxic conditions, the core–shell structure of nZVI is well maintained even after 72 h, and the corrosion products usually contain a mixture of wustite (FeO), goethite (α-FeOOH) and akaganeite (β-FeOOH). Under oxic conditions, the core–shell structure quickly collapses to flakes or acicular-shaped structures with crystalline lepidocrocite (γ-FeOOH) as the primary end product. This work provides detailed information and fills an important knowledge gap on the physicochemical characteristics and structural evolution of engineered nanomaterials in the environment.

Characterization of minerals, metals and materials

CERN Document Server

Hwang, Jiann-Yang; Bai, Chengguang; Carpenter, John; Cai, Mingdong; Firrao, Donato; Kim, Byoung-Gon

2012-01-01

This state-of-the-art reference contains chapters on all aspects of the characterization of minerals, metals, and materials. The title presents papers from one of the largest yearly gatherings of materials scientists in the world and thoroughly discusses the characterization of minerals, metals, and materials The scope includes current industrial applications and research and developments in the following areas:  Characterization of Ferrous Metals Characterization of Non-Ferrous Materials Characterization of Minerals and Ceramics Character

In situ remediation-released zero-valent iron nanoparticles impair soil ecosystems health: A C. elegans biomarker-based risk assessment

Energy Technology Data Exchange (ETDEWEB)

Yang, Ying-Fei; Cheng, Yi-Hsien; Liao, Chung-Min, E-mail: cmliao@ntu.edu.tw

2016-11-05

Highlights: • Fe{sup 0} NPs induced infertility risk in C. elegans. • A C.elegans-based probabilistic risk assessment model is developed. • In situ remediation-released Fe{sup 0} NPs impair soil ecosystems health. - Abstract: There is considerable concern over the potential ecotoxicity to soil ecosystems posed by zero-valent iron nanoparticles (Fe{sup 0} NPs) released from in situ environmental remediation. However, a lack of quantitative risk assessment has hampered the development of appropriate testing methods used in environmental applications. Here we present a novel, empirical approach to assess Fe{sup 0} NPs-associated soil ecosystems health risk using the nematode Caenorhabditis elegans as a model organism. A Hill-based dose-response model describing the concentration–fertility inhibition relationships was constructed. A Weibull model was used to estimate thresholds as a guideline to protect C. elegans from infertility when exposed to waterborne or foodborne Fe{sup 0} NPs. Finally, the risk metrics, exceedance risk (ER) and risk quotient (RQ) of Fe{sup 0} NPs in various depths and distances from remediation sites can then be predicted. We showed that under 50% risk probability (ER = 0.5), upper soil layer had the highest infertility risk (95% confidence interval: 13.18–57.40%). The margins of safety and acceptable criteria for soil ecosystems health for using Fe{sup 0} NPs in field scale applications were also recommended. Results showed that RQs are larger than 1 in all soil layers when setting a stricter threshold of ∼1.02 mg L{sup −1} of Fe{sup 0} NPs. This C. elegans biomarker-based risk model affords new insights into the links between widespread use of Fe{sup 0} NPs and environmental risk assessment and offers potential environmental implications of metal-based NPs for in situ remediation.

Copper increases reductive dehalogenation of haloacetamides by zero-valent iron in drinking water: Reduction efficiency and integrated toxicity risk.

Science.gov (United States)

Chu, Wenhai; Li, Xin; Bond, Tom; Gao, Naiyun; Bin, Xu; Wang, Qiongfang; Ding, Shunke

2016-12-15

The haloacetamides (HAcAms), an emerging class of nitrogen-containing disinfection byproducts (N-DBPs), are highly cytotoxic and genotoxic, and typically occur in treated drinking waters at low μg/L concentrations. Since many drinking distribution and storage systems contain unlined cast iron and copper pipes, reactions of HAcAms with zero-valent iron (ZVI) and metallic copper (Cu) may play a role in determining their fate. Moreover, ZVI and/or Cu are potentially effective HAcAm treatment technologies in drinking water supply and storage systems. This study reports that ZVI alone reduces trichloroacetamide (TCAcAm) to sequentially form dichloroacetamide (DCAcAm) and then monochloroacetamide (MCAcAm), whereas Cu alone does not impact HAcAm concentrations. The addition of Cu to ZVI significantly improved the removal of HAcAms, relative to ZVI alone. TCAcAm and their reduction products (DCAcAm and MCAcAm) were all decreased to below detection limits at a molar ratio of ZVI/Cu of 1:1 after 24 h reaction (ZVI/TCAcAm = 0.18 M/5.30 μM). TCAcAm reduction increased with the decreasing pH from 8.0 to 5.0, but values from an integrated toxic risk assessment were minimised at pH 7.0, due to limited removal MCAcAm under weak acid conditions (pH = 5.0 and 6.0). Higher temperatures (40 °C) promoted the reductive dehalogenation of HAcAms. Bromine was preferentially removed over chlorine, thus brominated HAcAms were more easily reduced than chlorinated HAcAms by ZVI/Cu. Although tribromoacetamide was more easily reduced than TCAcAm during ZVI/Cu reduction, treatment of tribromoacetamide resulted in a higher integrated toxicity risk than TCAcAm, due to the formation of monobromoacetamide (MBAcAm). Copyright © 2016 Elsevier Ltd. All rights reserved.

Immunogenicity and persistence of the 13-valent Pneumococcal Conjugate Vaccine (PCV13 in patients with untreated Smoldering Multiple Myeloma (SMM: A pilot study

Directory of Open Access Journals (Sweden)

Mathilde Bahuaud

2017-11-01

Full Text Available Smoldering multiple myeloma (SMM is an asymptomatic clonal plasma cell disorder that frequently progress to multiple myeloma (MM, a disease at high risk of pneumococcal infections. Moreover, if the polysaccharide vaccine is poorly immunogenic in MM, the 13-valent conjugated vaccine has never been tested in clonal plasma cell disorders. We evaluated its immunogenicity for 7 serotypes in 20 patients ≥ 50 years of age with smoldering multiple myeloma (SMM pre and post routine-vaccination with PCV13.Concentrations of IgG specific for 7 serotypes were measured at baseline, 1, 6, and 12 months after vaccination by standardized ELISA and an Opsonophagocytic Assay (OPA. The primary endpoint was the proportion of patients responding to at least 5 of the 7 serotypes by ELISA at one month.At 1 month post vaccination, 12 patients (60% were responders by ELISA, among whom 8 were also responders by OPA. At 6 months, 6 (30% of total of the 12 responders had persistent immunity, and only 2 (10% of total at 12 months. These results suggested a partial response in this population and a rapid decrease in antibody levels in the first months of vaccination.Although one injection of the 13-valent pneumococcal conjugate vaccine is immunogenic in some patients with SMM, the response is transient. Repeated injections are likely to be needed for effective and sustained protection. Keywords: Immunology, Vaccines, Infectious disease

Optical and structural studies of silver nanoparticles

International Nuclear Information System (INIS)

Temgire, M.K.; Joshi, S.S.

2004-01-01

Gamma radiolysis method was used to prepare polyvinyl alcohol (PVA) capped silver nanoparticles by optimizing various conditions like metal ion concentration and polymer (PVA) of different molecular weights. The role of different scavengers was also studied. The decrease in particle size was observed with increase in the molecular weight of capping agent. γ-radiolytic method provides silver nanoparticles in fully reduced and highly pure state. XRD (X-ray diffraction) technique confirmed the zero valent state of silver. Optical studies were done using UV-visible spectrophotometer to see the variation of electronic structure of the metal sol. Transmission Electron Microscopic (TEM) studies reveal the fcc geometry. The TEM show clearly split Debye-Scherrer rings. The d values calculated from the diffraction ring pattern are in perfect agreement with the ASTM data. Ag particles less than 10 nm are spherical in shape, whereas the particles above 30 nm have structure of pentagonal biprisms or decahedra, referred to as multiply twinned particles

4-Valent Human Papillomavirus (4vHPV) Vaccine in Preadolescents and Adolescents After 10 Years

DEFF Research Database (Denmark)

Ferris, Daron G; Samakoses, Rudiwilai; Block, Stanley L

2017-01-01

OBJECTIVES: We describe the final 10-year data for the long-term follow-up study of the 4-valent human papillomavirus (4vHPV) vaccine in preadolescents and adolescents. METHODS: In the base study (V501-018), 1661 sexually inactive boys and girls received the 4vHPV vaccine (early vaccination group...... assessed. Effectiveness was estimated by calculating the incidence rate of the primary endpoints (HPV types 6, 11, 16, and 18-related disease or persistent infection). RESULTS: For HPV types 6, 11, and 16, 89% to 96% of subjects remained seropositive through 10-years postvaccination. The preadolescents had...... 38% to 65% higher geometric mean titers at month 7, which remained 16% to 42% higher at 10 years compared with adolescents. No cases of HPV type 6, 11, 16, and 18-related diseases were observed. Ten subjects had a persistent infection of ≥6 months duration with vaccine-type HPV and 2 subjects had...

Structural Design and Sizing of a Metallic Cryotank Concept

Science.gov (United States)

Sleight, David W.; Martin, Robert A.; Johnson, Theodore F.

2013-01-01

This paper presents the structural design and sizing details of a 33-foot (10 m) metallic cryotank concept used as the reference design to compare with the composite cryotank concepts developed by industry as part of NASA s Composite Cryotank Technology Development (CCTD) Project. The structural design methodology and analysis results for the metallic cryotank concept are reported in the paper. The paper describes the details of the metallic cryotank sizing assumptions for the baseline and reference tank designs. In particular, the paper discusses the details of the cryotank weld land design and analyses performed to obtain a reduced weight metallic cryotank design using current materials and manufacturing techniques. The paper also discusses advanced manufacturing techniques to spin-form the cryotank domes and compares the potential mass savings to current friction stir-welded technology.

Development of Iridium Solid-state Reference Electrode for the Water Chemistry Status Measurement in Nuclear Power Plants

International Nuclear Information System (INIS)

Ku, Heekwon; Lim, Dongseok; Cho, Jaeseon

2013-01-01

The result of ECP measurement of piping material in nuclear power plant at low temperature using the developed iridium (SSRE) reference electrode is approximately -0.370V. Based on the various results of this study, the developed iridium (SSRE) reference electrode can be applied to the water chemistry environments of nuclear power plant. Various metallic materials used in a nuclear power plant have been exposed to a variety of water chemistry environments and the corrosion of metallic materials occurs due to the reactions between metal structures and water chemistry environments. Therefore, the management of the water chemistry factors is needed to prevent corrosion. The chemical factors affecting the corrosion are pH and Electrochemical Corrosion Potential (ECP). The world-wide studies suggest that ECP and pH are effective indicators for preventing the material damage from water chemistry condition. ECP and pH should be measured as the reference electrodes, and should show stable potential characteristics with fast responses. In this study, the iridium reference electrodes using a solid-state metal oxide electrode has been developed to measure effective indicators such as ECP and pH. The iridium (SSRE) reference electrode for the ECP measurement in water chemistry environment of nuclear power plants has been developed. A calibration for water chemistry measurement was performed by potential measurement of iridium (SSRE) reference electrode with Ag/AgCl (SSRE) reference electrode. The result exhibited a stable potential for 117 hours and a super-Nernst ian response with 63.12mV/p H. In this study, the iridium (SSRE) reference electrode shows super-Nernst ian characteristic and it may be caused by the property of electrolytically coated iridium oxide. Considering the long-term stability of the developed electrode, it is possible to apply as a reference electrode through calibration procedure

Enhanced removal of ethanolamine from secondary system of nuclear power plant wastewater by novel hybrid nano zero-valent iron and pressurized ozone initiated oxidation process.

Science.gov (United States)

Lee, Son Dong; Mallampati, Srinivasa Reddy; Lee, Byoung Ho

2017-07-01

Monoethanolamine (shortly ethanolamine (ETA)), usually used as a corrosion inhibitor, is a contaminant of wastewater from the secondary cooling system of nuclear power plants (NPPs) and is not readily biodegradable. We conducted various experiments, including treatments with nano zero-valent iron (nZVI), nano-iron/calcium, and calcium oxide (nFe/Ca/CaO) with ozone (O 3 ) or hydrogen peroxide (H 2 O 2 ) to reduce the concentration of ETA and to decrease the chemical demand of oxygen (COD) of these wastewaters. During this study, wastewater with ETA concentration of 7465 mg L -1 and COD of 6920 mg L -1 was used. As a result, the ETA concentration was reduced to 5 mg L -1 (a decrease of almost 100%) and COD was reduced to 2260 mg L -1 , a reduction of 67%, using doses of 26.8 mM of nZVI and 1.5 mM of H 2 O 2 at pH 3 for 3 h. Further treatment for 48 h allowed a decrease of COD by almost 97%. Some mechanistic considerations are proposed in order to explain the degradation pathway. The developed hybrid nano zero-valent iron-initiated oxidation process with H 2 O 2 is promising in the treatment of ETA-contaminated wastewaters.

9-Valent HPV vaccine for cancers, pre-cancers and genital warts related to HPV.

Science.gov (United States)

Pitisuttithum, Punnee; Velicer, Christine; Luxembourg, Alain

2015-01-01

Human papillomavirus (HPV) is the causative agent of nearly all cervical cancer cases as well as a substantial proportion of anal, vulvar, vaginal, penile and oropharyngeal cancers, making it responsible for approximately 5% of the global cancer burden. The first-generation HPV vaccines that is, quadrivalent HPV type 6/11/16/18 vaccine and bivalent HPV type 16/18 vaccine were licensed in 2006 and 2007, respectively. A second-generation 9-valent HPV type 6/11/16/18/31/33/45/52/58 vaccine with broader cancer coverage was initiated even before the first vaccines were approved. By preventing HPV infection and disease due to HPV31/33/45/52/58, the 9vHPV vaccine has the potential to increase prevention of cervical cancer from 70 to 90%. In addition, the 9vHPV vaccine has the potential to prevent 85-95% of HPV-related vulvar, vaginal and anal cancers. Overall, the 9vHPV vaccine addresses a significant unmet medical need, although further health economics and implementation research is needed.

Data of furfural adsorption on nano zero valent iron (NZVI) synthesized from Nettle extract.

Science.gov (United States)

Fazlzadeh, Mehdi; Ansarizadeh, Mohammad; Leili, Mostafa

2018-02-01

Among various water and wastewater treatment methods, adsorption techniques are widely used to remove certain classes of pollutants due to its unique features. Thus, the aim of this data article is to synthesize zero valent iron nanoparticles (NZVI) from Nettle leaf extract by green synthesis method as an environmentally friendly technique, and to evaluate it's efficiency in the removal of furfural from aqueous solutions. The data of possible adsorption mechanism and isotherm of furfural on the synthesized adsorbent are depicted in this data article. The data acquired showed that the adsorption trend follows the pseudo-second order kinetic model and that the Langmuir isotherm was suitable for correlation of equilibrium data with the maximum adsorption capacity of 454.4 mg/g. The information of initial furfural concentration, pH, adsorbent dosage and contact time effects on the removal efficiency are presented. Considering the findings data, the developed nanoparticle from Nettle leaf extract, as a low cost adsorbent, could be considered as promising adsorbent for furfural and probably similar organic pollutants removal from aqueous solutions.

High temperature fluidized bed zero valent iron process for flue gas nitrogen monoxide removal

International Nuclear Information System (INIS)

Cheng, C.Y.; Chen, S.S.; Tang, C.H.; Chang, Y.M.; Cheng, H.H.; Liu, H.L.

2008-01-01

Nitrogen oxides (NO x ) are generated from a variety of sources, and are critical components of photochemical smog. Zero valent iron (ZVI) has been used to remove NO x in a number of studies. The ZVI process requires no extra chemicals or catalysts. In this study, a fluidized ZVI process for removing NO x from flue gases was proposed. The study examined the effects of temperature, ZVI dosage and influent NO concentrations, and observed the kinetic effects between the fluidized ZVI and NO x . A life cycle analysis of the process was also provided. The parametric analysis was conducted in a series of column studies using a continuous emissions monitoring system. Minimum fluidization velocity equations were provided, and the drag coefficient was determined. Capacities of ZVI for NO removal at different temperatures were calculated. Results of the study suggested that temperature, influent concentrations, and flow rates all influenced kinetic coefficients. Different temperatures resulted in different rates of NO removal. It was concluded that between 673 K and 773 K, almost complete NO removals were achieved. 14 refs., 2 tabs., 9 figs

In situ synthesis of zero-valent silver nanoparticles in polymethylmethacrylate under high temperature

International Nuclear Information System (INIS)

Xiong Yuanlu; Luo Guoqiang; Chen Cheng; Yuan Huan; Shen Qiang; Li Meijuan

2012-01-01

In this work, the silver nanoparticles were synthesized in polymethylmethacrylate (PMMA) matrix under high temperature with polyvinylpyrrolidone (PVP) as additional stabilizer and N,N-dimethylformamide (DMF) as reaction medium. The UV-vis spectroscopy and transmission electron microscopy (TEM) were adopted to investigate the growth and shape conversion of Ag nanoparticles with the lacking of additional Ag source. The results showed that the stable zero-valent Ag in PMMA was obtained successfully. Two types of Ag nanoparticles, single-crystal and twinned ones, could form in the initial period. While the twinned ones will gradually disappear along with the reaction processed, the single-crystal ones could survive and slowly grow by consuming the Ag atoms which were etched form twinned ones. The single-crystal ones will take shape conversion from sphere to nanocube with nearly the same particle size after the total disappearance of twinned ones. The size and shape of Ag nanoparticles can be well controlled by reaction time. The high viscosity PMMA matrix plays the important role of controlling the growth of the Ag nanoparticles, and the PVP takes the responsibility of the shape conversion.

Estimation of the overall burden of cancers, precancerous lesions, and genital warts attributable to 9-valent HPV vaccine types in women and men in Europe

OpenAIRE

Hartwig , Susanne; St Guily , Jean Lacau; Dominiak-Felden , Géraldine; Alemany , Laia; De Sanjosé , Silvia

2017-01-01

Background In addition to cervical cancer, human papillomavirus (HPV) is responsible for a significant proportion of cancers and precancerous lesions of the vulva, vagina, anus, penis, head and neck, as well as genital warts. We estimated the annual number of new cases of these diseases attributable to 9-valent HPV vaccine types in women and men in Europe. Methods The annual number of new cancers of the cervix, vulva, vagina, anus, penis, and selected head and neck sites in the population of ...

Sensor for metal detection

KAUST Repository

Kodzius, Rimantas

2014-06-26

NOVELTY - The sensor has a microfluidic flow channel that is provided with an inlet port, an outlet port, and a detection chamber. The detection chamber is provided with a group of sensing electrodes (4) having a working electrode (8), a counter electrode (9), and a reference electrode (10). A flow sensor is configured to measure flow in the channel. A temperature sensor (6) is configured to measure temperature in the channel (3). An electrical connection is configured to connect the sensor to a sensing device. USE - Sensor for detecting metal such as toxic metal in sample such as clinical sample such as stool, saliva, sputum, bronchial lavage, urine, vaginal swab, nasal swab, biopsy, tissue, tears, breath, blood, serum, plasma, cerebrospinal fluid, peritoneal fluid, pleural fluid, pericardial fluid, joint fluid, and amniotic fluid, water sample, food sample, air sample, and soil sample (all claimed). ADVANTAGE - The sensor for use with the portable analytical instrument is configured for detection of metalsin samples. The sensor can provide the excellent solution for on-site metal detection, including heavy metal detection. The sensors can provide significant advantages in higher throughput, lower cost, at the same time being less labor intensive and less dependent on individual skills. The disposable design of the sensor, the enhanced reliability and repeatability of measurements can be obtained. The sensors can be widely applied in various industries. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a system for detecting metal in sample; and (2) a method for using sensor for detecting metal in sample. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the sensor prototype. Channel (3) Sensing electrodes (4) Temperature sensor (6) Working electrode (8) Counter electrode (9) Reference electrode (10)

Reliable reference electrodes for lithium-ion batteries

KAUST Repository

La Mantia, F.

2013-06-01

Despite the high attention drawn to the lithium-ion batteries by the scientific and industrial community, most of the electrochemical characterization is carried out using poor reference electrodes or even no reference electrode. In this case, the performances of the active material are inaccurate, especially at high current densities. In this work we show the error committed in neglecting the polarizability of lithium counter electrodes, and we propose two reference electrodes to use in organic electrolytes based on lithium salts, namely Li4Ti5O12 and LiFePO 4. In particular, it was observed that, the polarizability of the metallic lithium counter electrode has a relevant stochastic component, which renders measurements at high current densities (above 1 mA·cm - 2) in two electrode cells non reproducible.

Remediating sites contaminated with heavy metals

International Nuclear Information System (INIS)

Swartzbaugh, J.; Sturgill, J.; Cormier, B.; Williams, H.D.

1992-01-01

This article is intended to serve as a reference for decision makers who must choose an approach to remediate sites contaminated with heavy metals. Its purpose is to explain pertinent chemical and physical characteristics of heavy metals, how to use these characteristics to select remedial technologies, and how to interpret and use data from field investigations. Different metal species are typically associated with different industrial processes. The contaminant species behave differently in various media (i.e., groundwater, soils, air), and require different technologies for containment and treatment. We focus on the metals that are used in industries that generate regulated waste. These include steelmaking, paint and pigment manufacturing, metal finishing, leather tanning, papermaking, aluminum anodizing, and battery manufacturing. Heavy metals are also present in refinery wastes as well as in smelting wastes and drilling muds

Electric field mapping inside metallized film capacitors

DEFF Research Database (Denmark)

Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld

2015-01-01

(s) they suffered from accelerated testing. We have prepared film capacitors for analysis by micro-sectioning and verified the quality of the preparation procedure using optical and atomic force microscopy. The potential distribution in the layer structure (alternating 7 µm thick dielectric and 50-100 nm thick...... and durability and serves as verification that failure- and degradation mechanisms remain the same at different stress levels during accelerated testing. In this work we have used Kelvin probe force microscopy (KPFM) to analyze metallized film capacitors with the purpose of determining the degradation mechanism...... metal) of a new capacitor was used as reference. KPFM measurements on the degraded capacitors showed a change in contact potential difference from -0.61V on the reference capacitor to 3.2V on the degraded ones, indicating that corrosion of the metallization had happened. Studies also showed that some...

Immunogenicity of a 2-dose priming and booster vaccination with the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine

DEFF Research Database (Denmark)

Silfverdal, Sven Arne; Høgh, Birthe; Bergsaker, Marianne Riise

2009-01-01

BACKGROUND: The immunogenicity of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) was determined following a simplified 2-dose priming and the more commonly employed 3-dose priming both followed by a booster dose. METHODS: A total of 351 healthy....... RESULTS: Depending on the serotype, the percentages of subjects reaching the ELISA antibody threshold of 0.2 microg/mL were 92.8% to 98.0% following 2 primary doses and 96.1% to 100% following 3 primary doses except for serotype 6B (55.7% and 63.1%, respectively) and serotype 23F (69.3% and 77...

The Pneumococcal Serotype 15C Capsule Is Partially O-Acetylated and Allows for Limited Evasion of 23-Valent Pneumococcal Polysaccharide Vaccine-Elicited Anti-Serotype 15B Antibodies

OpenAIRE

Spencer, Brady L.; Shenoy, Anukul T.; Orihuela, Carlos J.; Nahm, Moon H.

2017-01-01

As a species, Streptococcus pneumoniae (the pneumococcus) utilizes a diverse array of capsular polysaccharides to evade the host. In contrast to large variations in sugar composition and linkage formation, O-acetylation is a subtle capsular modification that nonetheless has a large impact on capsular shielding and recognition of the capsule by vaccine-elicited antibodies. Serotype 15B, which is included in the 23-valent pneumococcal polysaccharide vaccine (PPV23), carries the putative O-acety...

Removal of As, Mn, Mo, Se, U, V and Zn from groundwater by zero-valent iron in a passive treatment cell: reaction progress modeling

Science.gov (United States)

Morrison, Stan J.; Metzler, Donald R.; Dwyer, Brian P.

2002-05-01

Three treatment cells were operated at a site near Durango, CO. One treatment cell operated for more than 3 years. The treatment cells were used for passive removal of contamination from groundwater at a uranium mill tailings repository site. Zero-valent iron [Fe(0)] that had been powdered, bound with aluminosilicate and molded into plates was used as a reactive material in one treatment cell. The others used granular Fe(0) and steel wool. The treatment cells significantly reduced concentrations of As, Mn, Mo, Se, U, V and Zn in groundwater that flowed through it. Zero-valent iron [Fe(0)], magnetite (Fe 3O 4), calcite (CaCO 3), goethite (FeOOH) and mixtures of contaminant-bearing phases were identified in the solid fraction of one treatment cell. A reaction progress approach was used to model chemical evolution of water chemistry as it reacted with the Fe(0). Precipitation of calcite, ferrous hydroxide [Fe(OH) 2] and ferrous sulfide (FeS) were used to simulate observed changes in major-ion aqueous chemistry. The amount of reaction progress differed for each treatment cell. Changes in contaminant concentrations were consistent with precipitation of reduced oxides (UO 2, V 2O 3), sulfides (As 2S 3, ZnS), iron minerals (FeSe 2, FeMoO 4) and carbonate (MnCO 3). Formation of a free gas phase and precipitation of minerals contributed to loss of hydraulic conductivity in one treatment cell.

EL SÍMBOLO COMO ESPACIO DE REUNIÓN ENTRE UN ORDEN SENSIBLE Y OTRO TRASCENDENTE EN LA POESÍA DE JOSÉ ÁNGEL VALENTE

Directory of Open Access Journals (Sweden)

Guillermo Aguirre Martínez

2012-07-01

Full Text Available Resumen: Según consideraba el propio José Ángel Valente, su poesía encontraba su origen en un mundo matriarcal, un universo de naturaleza sensible cuyo extremo opuesto lo observamos intensamente tratado en su última etapa creativa, dominada por el deseo de ascender hacia esferas puramente trascendentales donde la palabra encontrará su límite y se prestará, consecuentemente, a su pronta disolución. A través de este artículo estudiaremos aquel ámbito intermedio que va a quedar entre ambos extremos de su obra, coincidente con un espacio presentado a modo de cosmos rico en símbolos, orientados a reunir aquellos estratos materiales con aquellos otros espirituales propios de su creación poética. Abstract: As José Ángel Valente himself used to say, his poetry emerged from a matriarchal universe, a place dominated by water and earth. This sensitive world will be considered opposite to the transcendental object pursued towards the end of his last creative phase. The increasingly abstraction achieved in this phase will pose a well-known language problem: the word will be on the edge of the nothingness. Between these two extremes, a universe full of symbols will be created by connecting elements of the poet’s universe. All of these symbols, in their perfect way, will express the full unity between the material and spiritual aspects of Valente’s poetry.

Oxidation of ethane to ethanol by N2O in a metal-organic framework with coordinatively unsaturated iron(II) sites.

Science.gov (United States)

Xiao, Dianne J; Bloch, Eric D; Mason, Jarad A; Queen, Wendy L; Hudson, Matthew R; Planas, Nora; Borycz, Joshua; Dzubak, Allison L; Verma, Pragya; Lee, Kyuho; Bonino, Francesca; Crocellà, Valentina; Yano, Junko; Bordiga, Silvia; Truhlar, Donald G; Gagliardi, Laura; Brown, Craig M; Long, Jeffrey R

2014-07-01

Enzymatic haem and non-haem high-valent iron-oxo species are known to activate strong C-H bonds, yet duplicating this reactivity in a synthetic system remains a formidable challenge. Although instability of the terminal iron-oxo moiety is perhaps the foremost obstacle, steric and electronic factors also limit the activity of previously reported mononuclear iron(IV)-oxo compounds. In particular, although nature's non-haem iron(IV)-oxo compounds possess high-spin S = 2 ground states, this electronic configuration has proved difficult to achieve in a molecular species. These challenges may be mitigated within metal-organic frameworks that feature site-isolated iron centres in a constrained, weak-field ligand environment. Here, we show that the metal-organic framework Fe2(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) and its magnesium-diluted analogue, Fe0.1Mg1.9(dobdc), are able to activate the C-H bonds of ethane and convert it into ethanol and acetaldehyde using nitrous oxide as the terminal oxidant. Electronic structure calculations indicate that the active oxidant is likely to be a high-spin S = 2 iron(IV)-oxo species.

Review of metal-matrix encapsulation of solidified radioactive high-level waste

International Nuclear Information System (INIS)

Jardine, L.J.; Steindler, M.J.

1978-05-01

Literature describing previous and current work on the encapsulation of solidified high-level waste forms in a metal matrix was reviewed. Encapsulation of either stabilized calcine pellets or glass beads in alloys by casting techniques was concluded to be the most developed and direct approach to fabricating solid metal-matrix waste forms. Further characterizations of the physical and chemical properties of metal-matrix waste forms are still needed to assess the net attributes of metal-encapsulation alternatives. Steady-state heat transfer properties of waste canisters in air and water environments were calculated for four reference waste forms: (1) calcine, (2) glass monoliths, (3) metal-encapsulated calcine, and (4) metal-encapsulated glass beads. A set of criteria for the maximum allowable canister centerline and surface temperatures and heat generation rates per canister at the time of shipment to a Federal repository was assumed, and comparisons were made between canisters of these reference waste forms of the shortest time after reactor discharge that canisters could be filled and the subsequent ''interim'' storage times prior to shipment to a Federal repository for various canister diameters and waste ages. A reference conceptual flowsheet based on existing or developing technology for encapsulation of stabilized calcine pellets is discussed. Conclusions and recommendations are presented

Transition-metal impurities in semiconductors and heterojunction band lineups

Science.gov (United States)

Langer, Jerzy M.; Delerue, C.; Lannoo, M.; Heinrich, Helmut

1988-10-01

The validity of a recent proposal that transition-metal impurity levels in semiconductors may serve as a reference in band alignment in semiconductor heterojunctions is positively verified by using the most recent data on band offsets in the following lattice-matched heterojunctions: Ga1-xAlxAs/GaAs, In1-xGaxAsyP1-y/InP, In1-xGaxP/GaAs, and Cd1-xHgxTe/CdTe. The alignment procedure is justified theoretically by showing that transition-metal energy levels are effectively pinned to the average dangling-bond energy level, which serves as the reference level for the heterojunction band alignment. Experimental and theoretical arguments showing that an increasingly popular notion on transition-metal energy-level pinning to the vacuum level is unjustified and must be abandoned in favor of the internal-reference rule proposed recently [J. M. Langer and H. Heinrich, Phys. Rev. Lett. 55, 1414 (1985)] are presented.

Metal chalcogenide nanostructures for renewable energy applications

CERN Document Server

Qurashi, Ahsanulhaq

2014-01-01

This first ever reference book that focuses on metal chalcogenide semiconductor nanostructures for renewable energy applications encapsulates the state-of-the-art in multidisciplinary research on the metal chalcogenide semiconductor nanostructures (nanocrystals, nanoparticles, nanorods, nanowires,  nanobelts, nanoflowers, nanoribbons and more).  The properties and synthesis of a class of nanomaterials is essential to renewable energy manufacturing and this book focuses on the synthesis of metal chalcogendie nanostructures, their growth mechanism, optical, electrical, and other important prop

Removal of technetium, carbon tetrachloride, and metals from DOE properties. 1998 annual progress report

International Nuclear Information System (INIS)

Darab, J.G.; Mallouk, T.E.; Ponder, S.M.

1998-01-01

'The objective of the project is to develop and characterize supported reducing agents, and solid waste forms derived from them, which will be effective in the removal of transition metal ions, chlorinated organic molecules, and technetium from aqueous mixed wastes. This work follows the discovery that a nanoscale form of zero-valent iron, dispersed on high surface area supports, reduces metal ions (chromium, mercury, and lead) and rhenium (as a surrogate for technetium) to insoluble forms much faster than does unsupported iron. The scientific goals of the project are to better understand the mechanism of the reduction process, to develop supports that are compatible with a variety of mixed waste compositions, and to develop surface modifiers for the supported iron aggregates that will optimize their selectivity for the contaminants of interest. The support composition is of particular interest in the case of technetium (Tc) separation and stabilization in the Hanford tank wastes. While it is expected that pertechnetate will be reduced insoluble TcO 2 , the support material must be compatible with the vitrification process used in the final waste disposition. The surface modifications are also a focal point for Hanford applications because of the complex and variable makeup of the tank wastes. This report summarizes progress in the first 8 months of a 3-year collaborative project involving Penn State and Pacific Northwest National Laboratory (PNNL).'

Biocorrosion: towards understanding interactions between biofilms and metals.

Science.gov (United States)

Beech, Iwona B; Sunner, Jan

2004-06-01

The term microbially influenced corrosion, or biocorrosion, refers to the accelerated deterioration of metals owing to the presence of biofilms on their surfaces. The detailed mechanisms of biocorrosion are still poorly understood. Recent investigations into biocorrosion have focused on the influence of biomineralization processes taking place on metallic surfaces and the impact of extracellular enzymes, active within the biofilm matrix, on electrochemical reactions at the biofilm-metal interface.

Interatomic interaction of additive elements and their influence on the processes in the double metal solutions

Directory of Open Access Journals (Sweden)

Марина Анатоліівна Рябікіна

2016-07-01

Full Text Available Modern industry uses a lot of elements as additives to improve the service characteristics of metal products that are to be used for various purposes. These elements can be divided into two groups: the first group includes the elements interacting with iron and improving its characteristics (alloying elements, and the second group includes the elements, that modify the characteristics of the structure and properties in an undesirable direction. These are trace elements: S, P, O, As, and others in steel. The negative impact of these elements shows itself as banding, the formation of non-metallic inclusions, flakes, grain boundary segregations et al. The influence of the elements of the both groups on the properties of steel depends on the nature and level of interatomic interaction in the alloy. Computational and analytical study of the major impurity elements in steel impact on the interatomic bond strength and the probability of forming complexes, clusters, and chemical compounds with the basic alloying elements in the steel has been carried out in the work. The theoretical parameter which defines the strength of the ion-covalent bond of two atoms: non-metallic – metallic is the electronegativity of elements. The electronegativity difference of the metal and non-metallic elements increasing, the ionic bonding and thermodynamic stability of these compounds  increase. On the other hand, concentration of valent electrons is a universal characteristic of an atomic element which determines many of its properties, and especially the energy of interatomic interaction. Energy calculations of pairwise interatomic impurity elements: H, C, N, S, P, As interaction with Fe and major alloying elements in steel: Mn, Cr, Si, V, Al, Ti, W, Cu, Mo, Nb were made. It has been stated that all the impurity elements except phosphorus, hydrogen and arsenic have sufficient high adhesion with the majority of the metal elements in the modern steels. Phosphorus does

Adsorption of phenol on metal treated by granular activated carbon

International Nuclear Information System (INIS)

Kang, Kwang Cheol; Kwon, Soo Han; Kim, Seung Soo; Baik, Min Hoon; Choi, Jong Won; Kim, Jin Won

2007-01-01

In this study, the effect of metal treatment on Granular Activated Carbon (GAC) was investigated in the context of phenol adsorption. Cobalt(II) nitrate, and zinc(II) nitrate solution were used for metal treated. The specific surface area and the pore structure were evaluated from nitrogen adsorption data at 77 K. The phenol adsorption rates onto GAC were measured by UV-Vis spectrophotometer. Iodine adsorption capacity of Co-GAC is much better then that of the GAC. The Co-GAC with mesopore is more efficient than other adsorbents for the adsorption of polymer such as methyleneblue. The adsorption capacity of reference-GAC and metal-GAC were increased in order of Co-GAC>Zn-GAC>Reference-GAC, in spite of a decrease in specific surface area which was resulted from pore blocking by metal

Quantitative chemical state XPS analysis of first row transition metals, oxides and hydroxides

International Nuclear Information System (INIS)

Biesinger, M C; Payne, B P; McIntryre, N S; Hart, B R; Lau, L Wm; Grosvenor, A P; Smart, R StC

2008-01-01

Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available

Quantitative chemical state XPS analysis of first row transition metals, oxides and hydroxides

Energy Technology Data Exchange (ETDEWEB)

Biesinger, M C; Payne, B P; McIntryre, N S [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Hart, B R; Lau, L Wm [Surface Science Western, Room G1, Western Science Centre, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, A P [Department of Chemistry, Gunning/Lemieux Chemistry Centre, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Smart, R StC [ACeSSS, Applied Centre for Structural and Synchrotron Studies, University of South Australia, Mawson Lakes, SA 5095 (Australia)], E-mail: biesingr@uwo.ca

2008-03-15

Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available.

Economic and clinical evaluation of a catch-up dose of 13-valent pneumococcal conjugate vaccine in children already immunized with three doses of the 7-valent vaccine in Italy.

Science.gov (United States)

Boccalini, Sara; Azzari, Chiara; Resti, Massimo; Valleriani, Claudia; Cortimiglia, Martina; Tiscione, Emilia; Bechini, Angela; Bonanni, Paolo

2011-11-28

A new 13-valent conjugated polysaccharide vaccine (PCV13) against Streptococcus pneumoniae infections, which replaced the 7-valent vaccine (PCV7) in the regional immunization programmes for newborns and children who started but not completed the 3 doses schedule of PCV7, is available in Italy since 2010. The opportunity of administering a further dose of PCV13 to children under 5 years of age who had already completed their vaccination with PCV7, with the aim of extending the serotype coverage, triggered an animated scientific debate. The purpose of this study was to perform a clinical/economic evaluation of the administration of a dose of PCV13, in a catch-up programme, for children under 5 years of age, who had already received 3 doses of PCV7. A mathematical model of the clinical/economic impact of the adoption of 4 catch-up strategies with PCV13 (children up to 24, 36, 48 and 60 months old) was set up, with a vaccination coverage of 80%, versus immunization with 3 doses of PCV7 without the catch-up programme. The time span covered by the simulation was 5.5 years. The following clinical outcomes of infection were evaluated: hospitalised meningitis/sepsis, hospitalised bacteraemic pneumonias (complicated and uncomplicated), hospitalised non-bacteraemic pneumonias, and non-hospitalised pneumonias. The administration of one dose of PCV13 to children up to 60 months of age significantly reduces the number of cases of pneumococcal diseases (especially, non-hospitalised pneumonias, 80% of all events prevented, and hospitalised cases of non-bacteraemic pneumococcal pneumonias, 15% of all events prevented) and, subsequently, the relative cost for medical treatment. This results in savings for medical costs amounting to more than 1,000,000 Euros when vaccinating children under 24 months of age (up to almost 3 million Euros for children up to 60 months). More than half of those savings are attributable to avoided hospitalised cases of non-bacteraemic pneumococcal

Removal of Reactive Red 198 by Nanoparticle Zero Valent Iron in the Presence of Hydrogen Peroxide

Directory of Open Access Journals (Sweden)

Siroos Shojaei

2017-04-01

Full Text Available Although dyes are widely used in textile industries, they are carcinogenic, teratogenic and mutagenic. Industries discharge their wastewater containing a variety of colors into water resources and make harmful effect on the environment. The present study aims to Evaluate removal of reactive red 198 by nanoparticle zero valent iron (NZVI in the presence of hydrogen peroxide from aqueous solution. The effective parameters on the removal of dye such as the hydrogen peroxide concentration of NZVI, contact time, pH and dye concentration were investigated and optimized. According to the results, the combination of NZVI with hydrogen peroxide is more effective than single hydrogen peroxide. At pH = 4, contact time= 40 min, 200 M of hydrogen peroxide, dye concentration= 75 mg/L and concentration of NZVI 2g/L, color removal was achieved 91% approximately. Based on the results of experiments, using hydrogen peroxide- NZVI has high efficiency in removal of azo dye type.

Metals and cocoa products: a study on characterization of toxic and essential metals in chocolates

International Nuclear Information System (INIS)

Rahman, S.; Husnain, S.M.

2012-01-01

Metals (Pb, Cd, Ni, Fe, Cu, Zn and Mn) were assessed in 32 commonly consumed cocoa products (chocolates) prepared by different national and multinational companies. Significant differences were observed between the micro element contents of these varieties (P < 0.01). Frequent consumption of chocolates can enhance the intake of toxic metals in children. The concentration of Pb and Cd in cocoa powder is found to be highest 492 and 197 mu g/L followed by cocoa based chocolates 306 and 46.8 mu g/L, sugar based chocolates 209.8 and 40.3 mu g/L whereas it is least in milk based chocolates samples 88.3 and 33 mu g/L respectively. Weekly intake of toxic metals Pb, Cd and Ni was also calculated. Mean concentration of Pb and Cd was found below the provisional tolerable weekly intake defined by FAO/WHO. All essential elements were assessed for their weekly intake with the dietary reference intakes (DRI). Results were validated through the analysis of certified reference materials and determined metals concentrations were quite in good agreement with certified levels. Data was interpreted through cluster analysis and pattern recognition as depicted. The concentrations of Pb, Cd, Ni and Fe were found to be highest in the cocoa-based followed by milk-based and sugar-based chocolates. The daily intake of cocoa-based chocolates must be reduced as lead and cadmium intake can otherwise cross the limits set by Codex Alimentarius (FAO/WHO 2006). Raw materials should be checked before use for metal contents in order to decrease the concentrations of these metals in final chocolate products. (Orig./A.B.)

Metal decontamination for waste minimization using liquid metal refining technology

International Nuclear Information System (INIS)

Joyce, E.L. Jr.; Lally, B.; Ozturk, B.; Fruehan, R.J.

1993-01-01

The current Department of Energy Mixed Waste Treatment Project flowsheet indicates that no conventional technology, other than surface decontamination, exists for metal processing. Current Department of Energy guidelines require retrievable storage of all metallic wastes containing transuranic elements above a certain concentration. This project is in support of the National Mixed Low Level Waste Treatment Program. Because of the high cost of disposal, it is important to develop an effective decontamination and volume reduction method for low-level contaminated metals. It is important to be able to decontaminate complex shapes where surfaces are hidden or inaccessible to surface decontamination processes and destruction of organic contamination. These goals can be achieved by adapting commercial metal refining processes to handle radioactive and organic contaminated metal. The radioactive components are concentrated in the slag, which is subsequently vitrified; hazardous organics are destroyed by the intense heat of the bath. The metal, after having been melted and purified, could be recycled for use within the DOE complex. In this project, we evaluated current state-of-the-art technologies for metal refining, with special reference to the removal of radioactive contaminants and the destruction of hazardous organics. This evaluation was based on literature reports, industrial experience, plant visits, thermodynamic calculations, and engineering aspects of the various processes. The key issues addressed included radioactive partitioning between the metal and slag phases, minimization of secondary wastes, operability of the process subject to widely varying feed chemistry, and the ability to seal the candidate process to prevent the release of hazardous species

High-Permeability Magnetic Polymer Additives for Lightweight Electromagnetic Shielding

Science.gov (United States)

2015-08-01

incorporation) or chemical incorporation as part of the polymer chain backbone or linked as pendant groups.13 Many transition-metal organometallic...10.1002/9781119951438. 15. Poli R. Open-shell organometallics as a bridge between Werner-type and low-valent organometallic complexes: the effect

Nanoscale Zero-Valent Iron for Sulfide Removal from Digested Piggery Wastewater

Directory of Open Access Journals (Sweden)

Sheng-Hsun Chaung

2014-01-01

Full Text Available The removal of dissolved sulfides in water and wastewater by nanoscale zero-valent iron (nZVI was examined in the study. Both laboratory batch studies and a pilot test in a 50,000-pig farm were conducted. Laboratory studies indicated that the sulfide removal with nZVI was a function of pH where an increase in pH decreased removal rates. The pH effect on the sulfide removal with nZVI is attributed to the formation of FeS through the precipitation of Fe(II and sulfide. The saturated adsorption capacities determined by the Langmuir model were 821.2, 486.3, and 359.7 mg/g at pH values 4, 7, and 12, respectively, for nZVI, largely higher than conventional adsorbents such as activated carbon and impregnated activated carbon. The surface characterization of sulfide-laden nZVI using XPS and TGA indicated the formation of iron sulfide, disulfide, and polysulfide that may account for the high adsorption capacity of nZVI towards sulfide. The pilot study showed the effectiveness of nZVI for sulfide removal; however, the adsorption capacity is almost 50 times less than that determined in the laboratory studies during the testing period of 30 d. The complexity of digested wastewater constituents may limit the effectiveness of nZVI. Microbial analysis suggested that the impact of nZVI on the change of microbial species distribution was relatively noticeable after the addition of nZVI.

Reducing As availability in calcareous soils using nanoscale zero valent iron.

Science.gov (United States)

Azari, Prisa; Bostani, Abdol Amir

2017-09-01

Different methods, including the use of nanoscale zero-valent iron (NZVI), have been used to treat arsenic (As)-contaminated environments, with much less data on the use of NZVI in arsenic-calcareous-polluted soils. Accordingly, two different experiments were conducted to investigate the effects of NZVI on the removal of As from three different calcareous-polluted soils. In the first experiment, the effects of soil type (differing in the rate of clay particles and organic carbon including S1 (8.0 and 0.05%), S2 (20 and 0.2%), and S3 (20.5 and 0.8%)) and NZVI concentration (0, 50, and 100 g kg -1 of dry soil) on the removal of As extractable with distilled water were evaluated using a factorial design with three replicates. In the second experiment, the NZVI concentrations were reduced to 0, 2.5, 5.0, and 25 g kg -1 , and the NZVI contact time (0.5, 48, 96, 192, 384, and 768 h) was also tested. The analysis of variance in both experiments indicated the significant effects (P soils, with increasing NZVI concentration and contact time, the concentration of available As in the solution phase significantly decreased (P = 0.01). S3, due to a higher rate of organic matter, was less responsive to the NZVI treatments than the other soils. The effectiveness of the nanoremediation method, tested in this research work, on the stabilization of As in calcareous soils, is verified.

Conceptual design studies for the liquid metal target META:LIC

International Nuclear Information System (INIS)

Class, A.G.; Fazio, C.; Fetzer, J.R.; Gordeev, S.

2014-01-01

When the construction of ESS (European Spallation Source) in Sweden was initiated, the target station concept selection group decided to reevaluate a variety of target designs to respect new developments in their selection process. The META:LIC (MEgawatt TArget:Lead bIsmuth Cooled) target concept was developed following an extensive analysis of existing and new proposed designs and reached the level of proof of principle within only 2 years. ESS selected META:LIC as comparative target option for licensing purposes during the design update phase of ESS. The present work describes the design motivation of META:LIC referring to properties and design features of other targets. Therefore, META:LIC design is an evolutionary target which incorporates the extensive experience of liquid metal targets. The modular LBE (Lead Bismuth Eutectic) target concept with focus on the target module is introduced. Both, a window target option for the start of operation and a windowless option with extended lifetime are foreseen. Thermohydraulic simulations show that adequate window cooling can be realized. The stability of the free surface in the windowless option has been shown. Robust target module instrumentation based on free surface levels and the MEGAPIE experience is proposed for target control. Since the META:LIC concept foresees a horizontal extraction for both moderators and target from the monolith a safety concept based on the SNS and JSNS experience is proposed

Phase locking of a 2.7 THz quantum cascade laser to a microwave reference

NARCIS (Netherlands)

Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.; Klein, B.; Hesler, J. L.

2009-01-01

We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain

Effects of loading variables on fatigue-crack growth in liquid-metal environments

CSIR Research Space (South Africa)

Fernandes, PJL

1995-10-01

Full Text Available Liquid-metal-induced embrittlement (LMIE) refers to the loss of ductility in normally ductile metals and alloys when stressed while in contact with a liquid metal. In this study, the fatigue crack growth behaviour of brass in molten gallium...

Study on treatment of coking wastewater by biofilm reactors combined with zero-valent iron process

International Nuclear Information System (INIS)

Lai Peng; Zhao Huazhang; Zeng Ming; Ni Jinren

2009-01-01

Experiments were conducted to investigate the behavior of the integrated system with biofilm reactors and zero-valent iron (ZVI) process for coking wastewater treatment. Particular attention was paid to the performance of the integrated system for removal of organic and inorganic nitrogen compounds. Maximal removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH 3 -N) and total inorganic nitrogen (TIN) were up to 96.1, 99.2 and 92.3%, respectively. Moreover, it was found that some phenolic compounds were effectively removed. The refractory organic compounds were primarily removed in ZVI process of the integrated system. These compounds, with molecular weights either ranged 10,000-30,000 Da or 0-2000 Da, were mainly the humic acid (HA) and hydrophilic (HyI) compounds. Oxidation-reduction and coagulation were the main removal mechanisms in ZVI process, which could enhance the biodegradability of the system effluent. Furthermore, the integrated system showed a rapid recovery performance against the sudden loading shock and remained high efficiencies for pollutants removal. Overall, the integrated system was proved feasible for coking wastewater treatment in practical applications

Dynamics of metal-humate complexation equilibria as revealed by isotope exchange studies - a matter of concentration and time

Science.gov (United States)

Lippold, Holger; Eidner, Sascha; Kumke, Michael U.; Lippmann-Pipke, Johanna

2017-01-01

Complexation with dissolved humic matter can be crucial in controlling the mobility of toxic or radioactive contaminant metals. For speciation and transport modelling, a dynamic equilibrium process is commonly assumed, where association and dissociation run permanently. This is, however, questionable in view of reported observations of a growing resistance to dissociation over time. In this study, the isotope exchange principle was employed to gain direct insight into the dynamics of the complexation equilibrium, including kinetic inertisation phenomena. Terbium(III), an analogue of trivalent actinides, was used as a representative of higher-valent metals. Isotherms of binding to (flocculated) humic acid, determined by means of 160Tb as a radiotracer, were found to be identical regardless of whether the radioisotope was introduced together with the bulk of stable 159Tb or subsequently after pre-equilibration for up to 3 months. Consequently, there is a permanent exchange of free and humic-bound Tb since all available binding sites are occupied in the plateau region of the isotherm. The existence of a dynamic equilibrium was thus evidenced. There was no indication of an inertisation under these experimental conditions. If the small amount of 160Tb was introduced prior to saturation with 159Tb, the expected partial desorption of 160Tb occurred at much lower rates than observed for the equilibration process in the reverse procedure. In addition, the rates decreased with time of pre-equilibration. Inertisation phenomena are thus confined to the stronger sites of humic molecules (occupied at low metal concentrations). Analysing the time-dependent course of isotope exchange according to first-order kinetics indicated that up to 3 years are needed to attain equilibrium. Since, however, metal-humic interaction remains reversible, exchange of metals between humic carriers and mineral surfaces cannot be neglected on the long time scale to be considered in predictive

Nanoscale zero-valent iron incorporated with nanomagnetic diatomite for catalytic degradation of methylene blue in heterogeneous Fenton system.

Science.gov (United States)

Zha, Yiming; Zhou, Ziqing; He, Haibo; Wang, Tianlin; Luo, Liqiang

2016-01-01

Nanoscale zero-valent iron (nZVI) incorporated with nanomagnetic diatomite (DE) composite material was prepared for catalytic degradation of methylene blue (MB) in heterogeneous Fenton system. The material was constructed by two facile steps: Fe3O4 magnetic nanoparticles were supported on DE by chemical co-precipitation method, after which nZVI was incorporated into magnetic DE by liquid-phase chemical reduction strategy. The as-prepared catalyst was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, magnetic properties measurement and nitrogen adsorption-desorption isotherm measurement. The novel nZVI@Fe3O4-diatomite nanocomposites showed a distinct catalytic activity and a desirable effect for degradation of MB. MB could be completely decolorized within 8 min and the removal efficiency of total organic carbon could reach to 90% after reaction for 1 h.

Application of coupled zero-valent iron/biochar system for degradation of chlorobenzene-contaminated groundwater.

Science.gov (United States)

Zhang, Xu; Wu, Yanqing

2017-02-01

A novel iron-carbon micro-electrolysis system, bamboo-derived biochar coupled with zero-valent iron (ZVI), was investigated for chlorobenzene (CB)-contaminated groundwater removal. Influences of initial pH value, mass ratio of the ZVI/Biochar, initial CB concentration and ionic strength of the ZVI/Biochar micro-electrolysis were studied. The results indicated that the increase of initial pH led to the decrease of the CB removal efficiency. While the optimum mass ratio of ZVI to biochar was 2:1, the improved initial concentration and reaction time were 33.68 mg/L and 4 h, respectively. When pH of 2, mass ratio of 2:1 and reaction time of 4 h were applied, the CB removal efficiency was 99.92%. Enhanced degradation of CB was observed with increased Cl - concentration. When the Cl - concentration of 1,000 mg/L and reaction time of 1 h were applied, the CB removal efficiency arrived at 98.2%. Additionally, considering that biochar is cost-effective and readily produced, the coupled ZVI/Biochar micro-electrolysis could represent an effective approach for the treatment of groundwater containing chlorinated organic compounds in the future.

Arsenic Removal Efficiency in Aqueous Solutions Using Reverse Osmosis and Zero-Valent Iron Nanoparticles

Directory of Open Access Journals (Sweden)

Niloofar Saboori

2018-01-01

Full Text Available Arsenic is one of the most hazardous pollutants of water resources which threaten human health as well as animals. Therefore arsenic removal from water resources is the priority of health programs. There are several ways to remove arsenic. In this study, reverse osmosis and zero-valent iron nanoparticles methods have been used in a laboratory scale. To perform the test, the variables of temperature, arsenic concentration, pH, iron nanoparticle concentration and mixing time were considered. The results indicated that in both methods of reverse osmosis and iron nanoparticle, through increasing arsenic concentration, arsenic removal efficiency has been also increased. At concentration of 1.5 mg per litre in reverse osmosis method, the maximum efficiency was achieved by 98% and 95.2% removal of arsenic respectively. The effect of temperature and pH were similar in reverse osmosis; by increasing these two variables, arsenic removal percentage also increased. The highest removal rates of 95.98% and 95.56% were observed at pH 9 and Temperature 30oC respectively. The results indicated that in iron nanoparticles method the arsenic removal efficiency increases by increasing mixing time and temperature, while it decreases with increasing pH.

Polyelectrolyte multilayer film-assisted formation of zero-valent iron nanoparticles onto polymer nanofibrous mats

International Nuclear Information System (INIS)

Xiao Shili; Shi Xiangyang; Wu Siqi; Shen Mingwu; Guo Rui; Wang Shanyuan

2009-01-01

A facile approach that combines the electrospinning technique and layer-by-layer (LbL) assembly method has been developed to synthesize and immobilize zero-valent iron nanoparticles (ZVI NPs) onto the surface of nanofibers for potential environmental applications. In this approach, negatively charged cellulose acetate (CA) nanofibers fabricated by electrospinning CA solution were modified with bilayers composed of positively charged poly(diallyl-dimethyl-ammoniumchloride) (PDADMAC) and negatively charged poly(acrylic acid) (PAA) through electrostatic LbL assembly approach to form composite nanofibrous mats. The composite nanofibrous mats were immersed into the ferrous iron solution to allow Fe(II) ions to complex with the free carboxyl groups of PAA, and then ZVI NPs were immobilized onto the composite nanofibrous mats instantly by reducing the ferrous cations. Combined scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and thermogravimetry analysis demonstrated that the ZVI NPs are successfully synthesized and uniformly distributed into the polyelectrolyte (PE) multilayer films assembled onto the CA nanofibers. The present approach to synthesis ZVI NPs opens a new avenue to fabricating various materials with high surface area for environmental, catalytic, and sensing applications.

N-Acetyl-Cysteine as Effective and Safe Chelating Agent in Metal-on-Metal Hip-Implanted Patients: Two Cases

Directory of Open Access Journals (Sweden)

Andrea Giampreti

2016-01-01

Full Text Available Systemic toxicity associated with cobalt (Co and chromium (Cr containing metal hip alloy may result in neuropathy, cardiomyopathy, and hypothyroidism. However clinical management concerning chelating therapy is still debated in literature. Here are described two metal-on-metal hip-implanted patients in which N-acetyl-cysteine decreased elevated blood metal levels. A 67-year-old male who underwent Co/Cr hip implant in September 2009 referred to our Poison Control Centre for persisting elevated Co/Cr blood levels (from March 2012 to November 2014. After receiving oral high-dose N-acetyl-cysteine, Co/Cr blood concentrations dropped by 86% and 87% of the prechelation levels, respectively, and persisted at these latter concentrations during the following 6 months of follow-up. An 81-year-old female who underwent Co/Cr hip implant in January 2007 referred to our Centre for detection of high Co and Cr blood levels in June 2012. No hip revision was indicated. After a therapy with oral high-dose N-acetyl-cysteine Co/Cr blood concentrations decreased of 45% and 24% of the prechelation levels. Chelating agents reported in hip-implanted patients (EDTA, DMPS, and BAL are described in few cases. N-acetyl-cysteine may provide chelating sites for metals and in our cases reduced Co and Cr blood levels and resulted well tolerable.

Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon.

Science.gov (United States)

Lewis, Ariel S; Huntington, Thomas G; Marvin-DiPasquale, Mark C; Amirbahman, Aria

2016-05-01

Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of zero-valent iron and trivalent iron on UASB rapid start-up.

Science.gov (United States)

Wang, Jie; Fang, Hongyan; Jia, Hui; Yang, Guang; Gao, Fei; Liu, Wenbin

2018-01-01

In order to realize the rapid start-up of upflow anaerobic sludge blanket (UASB) reactor, the iron ion in different valence state was added to UASB. The results indicated that the start-up time of R3 (FeCl 3 ) was 48 h faster than that of R2 (zero-valent iron (ZVI)). It was because the FeCl 3 could rapidly promote granulation of sludge as a flocculant. However, ZVI released Fe 2+ through corrosion slowly, and then the Fe 2+ increased start-up speed by enhancing enzyme activity and enriching methanogens. In addition, the ZVI and FeCl 3 could promote hydrolysis acidification and strengthen the decomposition of long-chain fatty acids. The detection of iron ions showed that iron ions mainly existed in the sludge. Because the high concentration of Fe 2+ could inhibit anaerobic bacteria activity, excess Fe 3+ could be changed into iron hydroxide precipitation to hinder the mass transfer process of anaerobic bacteria under the alkaline condition. The FeCl 3 was suitable to be added at the initial stage of UASB start-up, and the ZVI was more fitted to be used in the middle stage of reactor start-up to improve the redox ability.

Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon

Science.gov (United States)

Lewis, Ariel S.; Huntington, Thomas G.; Marvin-DiPasquale, Mark C.; Amirbahman, Aria

2016-01-01

Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

Energy Technology Data Exchange (ETDEWEB)

Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

2016-07-26

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

Characterizing toxicity of metal-contaminated sediments from mining areas

Science.gov (United States)

Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.

2015-01-01

This paper reviews methods for testing the toxicity of metals associated with freshwater sediments, linking toxic effects with metal exposure and bioavailability, and developing sediment quality guidelines. The most broadly applicable approach for characterizing metal toxicity is whole-sediment toxicity testing, which attempts to simulate natural exposure conditions in the laboratory. Standard methods for whole-sediment testing can be adapted to test a wide variety of taxa. Chronic sediment tests that characterize effects on multiple endpoints (e.g., survival, growth, and reproduction) can be highly sensitive indicators of adverse effects on resident invertebrate taxa. Methods for testing of aqueous phases (pore water, overlying water, or elutriates) are used less frequently. Analysis of sediment toxicity data focuses on statistical comparisons between responses in sediments from the study area and responses in one or more uncontaminated reference sediments. For large or complex study areas, a greater number of reference sediments is recommended to reliably define the normal range of responses in uncontaminated sediments – the ‘reference envelope’. Data on metal concentrations and effects on test organisms across a gradient of contamination may allow development of concentration-response models, which estimate metal concentrations associated with specified levels of toxic effects (e.g. 20% effect concentration or EC20). Comparisons of toxic effects in laboratory tests with measures of impacts on resident benthic invertebrate communities can help document causal relationships between metal contamination and biological effects. Total or total-recoverable metal concentrations in sediments are the most common measure of metal contamination in sediments, but metal concentrations in labile sediment fractions (e.g., determined as part of selective sediment extraction protocols) may better represent metal bioavailability. Metals released by the weak-acid extraction

b-Cyclodextrin-assisted intervalence charge transfer in mixed- valent

Indian Academy of Sciences (India)

Administrator

The study of intramolecular electron transfer in redox active binuclear transition metal complexes is of great fundamental importance and is an area of contemporary research interest. Though there are many reports on the role of bridging ligands (BL) in tuning metal–metal interactions and intramolecular electron transfers in ...

Metal-enhanced galactic winds. I

International Nuclear Information System (INIS)

Vader, J.P.

1986-01-01

Supernova-driven gas loss during the early evolution of elliptical galaxies is considered as a possible explanation for the correlations among the observed chemical and structural properties of these systems. Mass loss from systems with a chemically homogeneous interstellar medium does not work. It is pointed out that supernova-driven winds are in fact metal-enhanced with respect to the star-forming gas because the metal production of any supernova that drives the wind is directly flushed out of the galaxy. The fraction of the total metal production lost in the wind is thus at least as large as the fraction epsilon(z) of supernovae that power the wind, independent of the total mass loss. As a corollary, the yield of heavy elements that are recycled in the galaxy is reduced by a factor 1 - epsilon(z). Metal-enhanced galactic winds, which can carry away a large fraction of the metal production in spite of a moderate total mass loss, offer a promising explanation for the low metallicities of dwarf elliptical galaxies. 62 references

GROUND WATER ARSENIC AND METALS TREATMENT USING A COMBINATION COMPOST-ZVI PRB

Science.gov (United States)

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The PRB is designed to treat arsenic an...

Comparative characterization of sewage sludge compost and soil: Heavy metal leaching characteristics.

Science.gov (United States)

Fang, Wen; Wei, Yonghong; Liu, Jianguo

2016-06-05

The leaching and accumulation of heavy metals are major concerns following the land application of sewage sludge compost (SSC). We comparatively characterized SSC, the reference soil, and the SSC amended soil to investigate their similarities and differences regarding heavy metal leaching behavior and then to evaluate the effect of SSC land application on the leaching behavior of soil. Results showed that organic matter, including both of particulate organic matter (POM) and dissolved organic matter (DOM), were critical factors influencing heavy metal leaching from both of SSC and the soil. When SSC was applied to soil at the application rate of 48t/ha, the increase of DOM content slightly enhanced heavy metal leaching from the amended soil over the applicable pH domain (6leaching behavior of heavy metals. The geochemical speciation modeling revealed that heavy metal speciation in the solid phase were similar between the reference soil and the amended soil. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanical and metal trades handbook

CERN Document Server

2012-01-01

Englische Ausgabe des vielfach bewährten Tabellenbuchs Metall, 45. Auflage. Translation of the 45th edition of the well-known "Tabellenbuch Metall". It is well suited for shop reference, tooling, machine building, maintenance and as a general book of knowledge. It is also useful for educational purposes, especially in practical work or curricula, continuing education programs. The contents of this book include tables and formulae in eight chapters. The tables contain the most important guidelines, designs, types, dimensions and standard values for their subject areas.

Destruction of TCE Using Oxidative and Reductive Pathways as Potential In-Situ Treatments for the Contaminated Paducah Groundwater

Energy Technology Data Exchange (ETDEWEB)

Lewis, S; Li, Y; Xu, J; Tee, Y; Lynch, Andrew

2007-05-01

When considering reductive technologies for ground water remediation, it is important to understand the underlying principles that govern kinetics of zero-valent metal dechlorination. Studies involving the use of nanoscale metals (characteristic length <100nm) for chloro-organic degradation have increased reaction rates by 1-2 orders of magnitude with minimal intermediate formation. Typically, these metals are synthesized using modifications of the aqueous phase reduction of metal ions using sodium borohydride presented by Glavee and coworkers. The use of a bimetallic system increases the reactivity of the particle surface by incorporating a second metal that can typically act as a hydrogenation promotor.

The use of metal hydrides in fuel cell applications

Directory of Open Access Journals (Sweden)

Mykhaylo V. Lototskyy

2017-02-01

Full Text Available This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field, as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally, the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.

Off-line testing of multifunctional surfaces for metal forming applications

DEFF Research Database (Denmark)

Godi, A.; Grønbæk, J.; De Chiffre, L.

2015-01-01

In this paper, Bending-Under-Tension, an off-line test method simulating deep-drawing, is chosen for investigating the effectiveness of multifunctional (MUFU) surfaces in metal forming operations. Four different MUFU surfaces, characterized by a plateau bearing area and grooves for lubricant...... retention, are manufactured, together with two polished references. During the tests, surface texture is the only variable. The results show how MUFU surfaces perform better than the polished references, which produce severe galling, while MUFU surfaces with low bearing area display no clear evidence...... of galling. Metal-to-metal contact occurs anyway, but the strip material is pulverized and deposited onto the tool instead of cold-welding to it. The pockets create a discontinuity on the texture hindering pick-up propagation....

The Fundamentals of Corrosion of Metals and Their Application into Practice

International Nuclear Information System (INIS)

Byeon, Su Il

2006-07-01

This book introduce electrokinetic phenomenon, balanced electrochemistry of corrosion of metals about balancing of electrode reaction, equilibrium diagram of electrochemistry, conception of electrode reference electrode, and contact phenomenon, electrochemical reaction of corrosion of metals, alternating current impedance spectroscope of quasi-stationary state, electrochemistry of electric double layer, application of mechanical chemical reaction of corrosion of metals like electrochemical corrosion.

Treatment of Arsenic, Heavy Metals, and Acidity Using a Mixed ZVI-Compost PRB

Science.gov (United States)

A 30-month performance evaluation of a pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel installed at a former phosphate fertilizer manufacturing facility was conducted. The PRB is designed to remove ...

Microperoxidase-8 : tuning of its catalysis and reactivity

NARCIS (Netherlands)

Primus, J.L.A.

2000-01-01

In this thesis, microperoxidase-8, Fe ^III MP-8, and the manganese variant Mn ^III MP-8, were studied. Insight in i) the mechanism of oxygen exchange between the oxo group of porphyrin high-valent metal-oxo species and solvent, ii) their

Mandorla: the Mysticism and the Body in Saint John of the Cross and José Ángel Valente

Directory of Open Access Journals (Sweden)

Marlena Krupa

2017-01-01

Full Text Available The poems from the volume El fulgor by José Ángel Valente —the enthusiastic reader of Saint John of the Cross’s poetry— converses with The Spiritual Canticle of the Spanish mystic. This dialogue surprises because it does not recall things which belong to the spirit, but, on the contrary, things which are related to the body. The present article tries to answer the following questions: 1 How does the mystic from the 16th century and the contemporary poet inspired by his works describe, both in their prose and poetry, the relationship between the body and the interior experience of a human being? Why did erotic love convert into the symbol of the deepest relationship between the soul and God? What are the reasons for the tendency of contemporary artists to reflect their inspirations towards the images of erotic acts by the mystical works?

The nanotoxicology of a newly developed zero-valent iron nanomaterial for groundwater remediation and its remediation efficiency assessment combined with in vitro bioassays for detection of dioxin-like environmental pollutants

OpenAIRE

Schiwy, Andreas Herbert

2016-01-01

The assessment of chemicals and new compounds is an important task of ecotoxicology. In this thesis a newly developed zero-valent iron material for nanoremediation of groundwater contaminations was investigated and in vitro bioassays for high throughput screening were developed. These two elements of the thesis were combined to assess the remediation efficiency of the nanomaterial on the groundwater contaminant acridine. The developed in vitro bioassays were evaluated for quantification of th...

Method for hydrometallurgical recovery of selected metals

International Nuclear Information System (INIS)

Lorenz, G.; Schaefer, B.; Balzat, W.

1988-01-01

The method for hydrometallurgical recovery of selected metals refers to ore dressing by means of milling and alkaline leaching of metals, preferably uranium. By adding CaO during wet milling, Na + or K + ions of clayey ores are replaced by Ca 2+ ions. Due to the ion exchange processes, the uranium bonded with clays becomes more accessible to the leaching solution. The uranium yield increases and the consumption of reagents decreases

Bioaccumulation of heavy metals in two wet retention ponds

DEFF Research Database (Denmark)

Søberg, Laila C.; Vollertsen, Jes; Blecken, Godecke-Tobias

2016-01-01

Metal accumulation in stormwater ponds may contaminate the inhabiting fauna, thus jeopardizing their ecosystem servicing function. We evaluated bioaccumulation of metals in natural fauna and caged mussel indicator organisms in two wet retention ponds. Mussel cages were distributed throughout...... the ponds to detect bioaccumulation gradients and obtain a time-integrated measure of metal bioavailability. We further investigated if sediment metal concentrations correlate with those in the fauna and mussels. Metal concentrations in the fauna tended to be higher in the ponds than in a reference lake......, but statistical significance was only shown for Cu. Positive correlations were found for some metals in fauna and sediment. Sediment metal concentrations in one pond decreased from inlet to outlet while no gradients were observed in the mussels in either pond. These findings indicate that metal accumulation...

Metal contamination of home garden soils and cultivated vegetables in the province of Brescia, Italy: implications for human exposure.

Science.gov (United States)

Ferri, Roberta; Hashim, Dana; Smith, Donald R; Guazzetti, Stefano; Donna, Filippo; Ferretti, Enrica; Curatolo, Michele; Moneta, Caterina; Beone, Gian Maria; Lucchini, Roberto G

2015-06-15

For the past century, ferroalloy industries in Brescia province, Italy produced particulate emissions enriched in manganese (Mn), lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), iron (Fe), and aluminum (Al). This study assessed metal concentrations in soil and vegetables of regions with varying ferroalloy industrial activity levels. Home gardens (n=63) were selected in three regions of varying ferroalloy plant activity durations in Brescia province. Total soil metal concentration and extractability were measured by X-Ray Fluorescence (XRF), aqua regia extraction, and modified Community Bureau of Reference (BCR) sequential extraction. Unwashed and washed spinach and turnips cultivated in the same gardens were analyzed for metal concentrations by flame atomic absorption spectrometry. Median soil Al, Cd, Fe, Mn, Pb, and Zn concentrations were significantly higher in home gardens near ferroalloy plants compared to reference home gardens. The BCR method yielded the most mobile soil fraction (the sum of extractable metals in Fractions 1 and 2) and all metal concentrations were higher in ferroalloy plant areas. Unwashed spinach showed higher metal concentrations compared to washed spinach. However, some metals in washed spinach were higher in the reference area likely due to history of agricultural product use. Over 60% of spinach samples exceeded the 2- to 4-fold Commission of European Communities and Codex Alimentarius Commission maximum Pb concentrations, and 10% of the same spinach samples exceeded 2- to 3-fold maximum Cd concentrations set by both organizations. Turnip metal concentrations were below maximum standard reference values. Prolonged industrial emissions increase median metal concentrations and most soluble fractions (BCR F1+F2) in home garden soils near ferroalloy plants. Areas near ferroalloy plant sites had spinach Cd and Pb metal concentrations several-fold above maximum standard references. We recommend thorough washing of vegetables

Characterizing toxicity of metal-contaminated sediments from mining areas

International Nuclear Information System (INIS)

Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.

2015-01-01

Highlights: • We review methods for testing toxicity of sediments affected by metals. • Toxicity testing provides site-specific assessment of impacts on resident biota. • Goals are to document extent of toxicity and associations with metal exposure. • Need to characterize bioavailability of metals in sediment and pore water. • Toxicity data is basis for guidelines used to predict hazards of metal toxicity. - Abstract: This paper reviews methods for testing the toxicity of metals associated with freshwater sediments, linking toxic effects with metal exposure and bioavailability, and developing sediment quality guidelines. The most broadly applicable approach for characterizing metal toxicity is whole-sediment toxicity testing, which attempts to simulate natural exposure conditions in the laboratory. Standard methods for whole-sediment testing can be adapted to test a wide variety of taxa. Chronic sediment tests that characterize effects on multiple endpoints (e.g., survival, growth, and reproduction) can be highly sensitive indicators of adverse effects on resident invertebrate taxa. Methods for testing of aqueous phases (pore water, overlying water, or elutriates) are used less frequently. Analysis of sediment toxicity data focuses on statistical comparisons between responses in sediments from the study area and responses in one or more uncontaminated reference sediments. For large or complex study areas, a greater number of reference sediments is recommended to reliably define the normal range of responses in uncontaminated sediments – the ‘reference envelope’. Data on metal concentrations and effects on test organisms across a gradient of contamination may allow development of concentration-response models, which estimate metal concentrations associated with specified levels of toxic effects (e.g. 20% effect concentration or EC20). Comparisons of toxic effects in laboratory tests with measures of impacts on resident benthic invertebrate

Atmospheric heavy metal deposition in the Copenhagen area

Energy Technology Data Exchange (ETDEWEB)

Andersen, A; Hovmand, M F; Johnsen, I

1978-10-01

Transport of heavy metals from the atmosphere to the soil and vegetation takes place by dust fall, bulk precipitation, and gas/aerosol adsorption processes. Atmospheric dry and wet deposition of the heavy metals lead, zinc, nickel, vanadium, iron, and copper over the Copenhagen area was measured by sampling in plastic funnels from 17 stations throughout the area for 12 months. Epigeic bryophytes, epiphytic lichen, and topsoil samples were analyzed. A linear correlation between bulk precipitation and heavy metal concentration in lichens and bryophytes was found. An exponential correlation between bulk precipitation and heavy metal concentration in soil was noted. Regional variation of the heavy metal levels in the Copenhagen area was described, and three sub-areas with high metal burdens were distinguished. (10 diagrams, 8 graphs, 13 references, 2 tables)

TREATMENT OF ARSENIC AND METALS IN GROUND WATER USING A COMPOST-ZVI PRB

Science.gov (United States)

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The PRB is designed to treat arsenic an...

Metal assessment in sediments from the Guarapiranga Reservoir

International Nuclear Information System (INIS)

Coutinho, Suellen N.; Figueiredo, Ana Maria G.; Quináglia, Gilson A.

2017-01-01

The study of the distribution of metals in sediments is very important from the point of view of environmental pollution once the sediment concentrates metals in aquatic systems and represents a relevant contamination monitor. The analysis of sediments has been used to evaluate the quality of aquatic systems in relation to the concentration of metals. This study aimed to assess sediment contamination by metals in the Guarapiranga Reservoir. Sediment and water samples were analyzed by ICP OES (Inductively Coupled Plasma Optical Emission Spectrometry) for As, Cd, Cr, Cu, Ni, Pb and Zn and by CV AAS (Cold Vapor Atomic Absorption Spectrophotometry) for Hg. The sediment samples results were compared to TEL (Threshold Effect Level) and PEL (Probable Effect Level) guidance values and RRV (Reference Regional Values). Geoaccumulation Index (I geo ) was calculated to evaluate metals pollution degree using reference values established for metals and metalloids in sediments from the Upper Tietê Basin and E H -pH diagrams were applied to explain chemical forms and bioavailability of toxic metals in sediment samples. In general, most of the analyzed elements exceeded TEL values and Cr, Cu and Zn exceeded RRV guidelines. The high concentrations of Cu found in this reservoir can be explained by the frequent application of CuSO 4 algicide, mainly at sampling site S-03. The I geo indicated moderated polluted sediments by Zn and moderately to extremely polluted sediments by Cu, especially at S-03, in agreement with the TEL, PEL and RRV values comparison. These results may indicate potential risk of the reservoir water quality. (author)

Dichotomous classification of black-colored metal using spectral analysis

Directory of Open Access Journals (Sweden)

Abramovich A.O.

2017-05-01

Full Text Available The task of detecting metal objects in different environments has always been important. To solve it metal detectors are used. They are designed to detect and identify objects that in their electric or magnetic properties different from the environment in which they are located. The most common among them are the metal detectors of the «detection of very low frequency» type (Very Low Frequency (VLF detectors. They use eddy current testing for detecting metal targets, which solves the problem of dichotomous distinction, that is a problem of splitting (or set into two parts (subsets: black or colored target. The target distinction is performed by a threshold level of the received signal. However, this approach does not allow to identify the type of target, if two samples of different metals are nearby. To overcome the above described limitations we propose another way of distinction based on the use of spectral analysis, which occurs in the metal detector antenna by Foucault current. We show that the problem of dichotomous distinction can be solved in just a measurement of width and area by the envelope of amplitude spectrum (hereinafter spectrum of the received signal. In this regard the laboratory model using eddy current metal detector will combat withdrawal from two samples – steel and copper, located along and calculate its range. The task of distinguishing between metal targets reduced to determining the hit spectra of reference samples obtained spectrum. The ratio between the areas is measured and reference spectra indicates the percentage of specific metals (e.g. two identical samples of different metals lying side by side. Signal processing is performed by specially designed program that compares two spectra along posted samples of black and colored metals with base.

Potential environmental implications of nanoscale zero-valent iron particles for environmental remediation

Directory of Open Access Journals (Sweden)

Min-Hee Jang

2014-12-01

Full Text Available Objectives Nanoscale zero-valent iron (nZVI particles are widely used in the field of various environmental contaminant remediation. Although the potential benefits of nZVI are considerable, there is a distinct need to identify any potential risks after environmental exposure. In this respect, we review recent studies on the environmental applications and implications of nZVI, highlighting research gaps and suggesting future research directions. Methods Environmental application of nZVI is briefly summarized, focusing on its unique properties. Ecotoxicity of nZVI is reviewed according to type of organism, including bacteria, terrestrial organisms, and aquatic organisms. The environmental fate and transport of nZVI are also summarized with regards to exposure scenarios. Finally, the current limitations of risk determination are thoroughly provided. Results The ecotoxicity of nZVI depends on the composition, concentration, size and surface properties of the nanoparticles and the experimental method used, including the species investigated. In addition, the environmental fate and transport of nZVI appear to be complex and depend on the exposure duration and the exposure conditions. To date, field-scale data are limited and only short-term studies using simple exposure methods have been conducted. Conclusions In this regard, the primary focus of future study should be on 1 the development of an appropriate and valid testing method of the environmental fate and ecotoxicity of reactive nanoparticles used in environmental applications and 2 assessing their potential environmental risks using in situ field scale applications.

Persistence of commercial nanoscaled zero-valent iron (nZVI) and by-products

International Nuclear Information System (INIS)

Adeleye, Adeyemi S.; Keller, Arturo A.; Miller, Robert J.; Lenihan, Hunter S.

2013-01-01

The use of nanoscale zero-valent iron (nZVI) for in situ remediation of a wide scale of environmental pollutants is increasing. Bench and field pilot studies have recorded successful cleanup of many pollutants using nZVI and other iron-mediated nanoparticles. However, a major question remains unanswered: what is the long-term environmental fate of the iron nanoparticles used for remediation? We aged three types of commercial nZVI in different aqueous media, including a groundwater sample, under aerobic and anaerobic conditions for 28 days, and found that the bulk of the nZVI injected into polluted sites will end up in the sediment phase of the aquifer. This is mainly due to aggregation-induced sedimentation of the nZVI and the insoluble iron oxides formed when nZVI undergoes corrosion. Iron concentrations >500 g/kg were detected in sediment, a loading level of iron that may potentially affect some organisms and also reduce the permeability of aquifers. Dissolved and suspended iron concentrations initially surged when nZVI was applied, but iron decreased steadily in the supernatant and suspended sediment as the bulk of the iron partitioned into the sediment. Solution and surface chemistry of the iron species showed that nZVI remains reactive for more than 1 month, and that the reactivity of iron and its transformations are governed by environmental factors, including the presence of different ions, ionic strength, natural organic matter, and pH.

Complexes of natural carbohydrates with metal cations

International Nuclear Information System (INIS)

Alekseev, Yurii E; Garnovskii, Alexander D; Zhdanov, Yu A

1998-01-01

Data on the interaction of natural carbohydrates (mono-, oligo-, and poly-saccharides, amino sugars, and natural organic acids of carbohydrate origin) with metal cations are surveyed and described systematically. The structural diversity of carbohydrate metal complexes, caused by some specific features of carbohydrates as ligands, is demonstrated. The influence of complex formation on the chemical properties of carbohydrates is discussed. It is shown that the formation of metal complexes plays an important role in the configurational and conformational analysis of carbohydrates. The practical significance of the coordination interaction in the series of carbohydrate ligands is demonstrated. The bibliography includes 571 references.

Phase Locking of a 2.7 THz Quantum Cascade Laser to a Microwave Reference

Science.gov (United States)

Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Hu, Q.;

Calibrating NIST SRM 683 as A New International Reference Standard for Zn Isotopes

Science.gov (United States)

Yang, Y.; Zhang, X.; Yu, H.; Huang, F.

2017-12-01

Zinc isotopes have been widely applied in the cosmochemical, geochemical, and environmental studies (Moynier et al. 2017). Obtaining precise Zn isotopic data for inter-laboratory comparison is a prerequisite to these applications. Currently, the JMC3-0749L is the primary reference standard for Zn isotopes (Albarède 2004), but it is not commercially available now. Thus, it is necessary to calibrate a new international primary reference standard for Zn isotopic analysis. Chen et al. (2016) showed that NIST SRM 683 (a pure Zn metal nugget of 140 grams) has a δ66ZnJMC of 0.12‰, which is falling within the range of natural Zn isotopic compositions, and it may a good candidate for the next generation of international reference standard (Chen et al. 2016). In order to further examine whether NIST SRM 683 has a homogeneous Zn isotopic composition, we measured more NIST SRM 683 by double-spike methods using MC-ICPMS (Conway et al. 2013). The metal nuggets of NIST SRM 683 were intensively sampled by micro-drilling. Zinc isotope analyses for two nuggets show that they have δ66Zn of 0.14 ± 0.02‰ (2SD, N = 32) and 0.13 ± 0.02‰ (2SD, N = 33), respectively. These values are similar to those of two Zn metal nuggets (0.11 ± 0.02‰ vs. 0.12 ± 0.02‰) reported previously by Chen et al. (2016). We fully dissolved one nugget, producing pure Zn solution with identical Zn isotopic composition with the drilling samples. All results strongly support that NIST SRM 683 is homogeneous in Zn isotopic compositions which could be an ideal candidate for the next reference for Zn isotopes. Tests on more metal nuggets will be performed in a few months for further confirming the Zn isotope compositions and homogeneity. Reference: Albarède et al., 2004. 'The stable isotope geochemistry of copper and zinc', Reviews in Mineralogy and Geochemistry, 55: 409-27. Chen et al., 2016. 'Zinc Isotopic Compositions of NIST SRM 683 and Whole-Rock Reference Materials', Geostandards and

Combined zero-valent iron and fenton processes for the treatment of Brazilian TNT industry wastewater

International Nuclear Information System (INIS)

Barreto-Rodrigues, Marcio; Silva, Flavio T.; Paiva, Teresa C.B.

2009-01-01

The environmental impact caused by the production of explosives made from nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT) is currently a major concern, mainly due to their toxic nature, a fact that makes these compounds highly harmful. This work evaluated a continual system treatment reactor (CSTR) consisting of column zero-valent iron and a system to promote a fenton reaction in order to create possible definitive routines for treating effluents originating from the TNT production process. The spectrophotometric results demonstrated that this combination of processes was highly efficient in promoting the removal of all the absorbed species at 290 nm and the visible region of the specter. The results also revealed that the combination of treatments was significantly efficient in terms of correcting the effluent's main parameters of relevance, mainly COD (95.5% reduction) and TNT concentration, whose total was converted into nitrous and phenolic compounds and, additionally, the acute toxicity was also significantly reduced (95%). These results indicate that the strategy can serve as an efficient option for effluent treatment, for release into the receiving body, or eventually for use as industrial reuse water.

Investigation of Pb(II Removal from Aqueous Solutions Using Modified Nano Zero-Valent Iron Particles

Directory of Open Access Journals (Sweden)

Amirhossein Ramezanpoor

2014-05-01

Full Text Available This research was conducted in experimental scale with the aim of investigation effect of polyacrylic acid-stabilized zero-valent iron nanoparticles (PAA-nZVI on lead removal from aqueous solution. In this regards, NZVI was synthesized with polyacrylic acid and their size and morphological characteristics were examined via X-ray diffraction (XRD, Scanning Electron Microscopy (SEM and Fourier Transmission Infrared Spectroscopy (FTIR. To study the effect of PAA-nZVI on lead removal, pH of aqueous solution, contact time, PAA-NZVI concentration  and initial Pb(II concentration were considered as variables. Furthermore, the experimental data of Pb(II  removal were fitted using three kinetic models, namely Zero-order, First-order and Second-order.The results of experiments showed that maximum Pb(II removal efficiency was observed at pH=5, 15 min contact time and 5 g/L PAA-nZVI concentration. Moreover, the results of kinetic studies indicated that among all applied kinetic models, First-order kinetic model had more better prediction than other kinetic models ofPb(II removal. Based on the results of present research, PAA-NZVI is an efficient agent to remove Pb(II from aqueous solutions.

Zero-valent iron nanoparticles in treatment of acid mine water from in situ uranium leaching.

Science.gov (United States)

Klimkova, Stepanka; Cernik, Miroslav; Lacinova, Lenka; Filip, Jan; Jancik, Dalibor; Zboril, Radek

2011-02-01

Acid mine water from in situ chemical leaching of uranium (Straz pod Ralskem, Czech Republic) was treated in laboratory scale experiments by zero-valent iron nanoparticles (nZVI). For the first time, nZVI were applied for the treatment of the real acid water system containing the miscellaneous mixture of pollutants, where the various removal mechanisms occur simultaneously. Toxicity of the treated saline acid water is caused by major contaminants represented by aluminum and sulphates in a high concentration, as well as by microcontaminants like As, Be, Cd, Cr, Cu, Ni, U, V, and Zn. Laboratory batch experiments proved a significant decrease in concentrations of all the monitored pollutants due to an increase in pH and a decrease in oxidation-reduction potential related to an application of nZVI. The assumed mechanisms of contaminants removal include precipitation of cations in a lower oxidation state, precipitation caused by a simple pH increase and co-precipitation with the formed iron oxyhydroxides. The possibility to control the reaction kinetics through the nature of the surface stabilizing shell (polymer vs. FeO nanolayer) is discussed as an important practical aspect. Copyright © 2010 Elsevier Ltd. All rights reserved.

Recovery of indium ions by nanoscale zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Chen, Wen; Su, Yiming [Tongji University, State Key Laboratory of Pollution Control and Resources Reuse (China); Wen, Zhipan [Wuhan Institute of Technology, School of Chemistry and Environmental Engineering (China); Zhang, Yalei; Zhou, Xuefei, E-mail: zhouxuefei@tongji.edu.cn; Dai, Chaomeng, E-mail: daichaomeng@tongji.edu.cn [Tongji University, State Key Laboratory of Pollution Control and Resources Reuse (China)

2017-03-15

Indium and its compounds have plenty of industrial applications and high demand. Therefore, indium recovery from various industrial effluents is necessary. It was sequestered by nanoscale zero-valent iron (nZVI) whose size mainly ranged from 50 to 70 nm. Adsorption kinetics and isotherm, influence of pH, and ionic strength were thoroughly investigated. The reaction process was well fitted to a pseudo second-order model, and the maximum adsorption capacity of In(III) was 390 mg In(III)/g nZVI similar to 385 mg In(III)/g nZVI at 298 K calculated by Langmuir model. The mole ratio of Fe(II) released to In(III) immobilized was 3:2, which implied a special chemical process of co-precipitation combined Fe(OH){sub 2} with In(OH){sub 3}. Transmission electron microscopy with an energy-disperse X-ray (TEM-EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize surface morphology, corrosion products, and valence state of indium precipitate formed on nanoparticles. The structural evolution changed from core-shell structure of iron oxide to sheet structure of co-precipitation, to sphere structure that hydroxide gradually dissolved as the pH decreased, and to cavity structures for the pH continually decreased. Furthermore, below pH 4.7, the In(III) enrichment was inhibited for the limited capacity of co-precipitation. Also, it was found that Ca{sup 2+} and HPO{sub 4}{sup 2−} have more negative influence on In(III) recovery compared with Na{sup +}, NO{sub 3}{sup −}, HCO{sub 3}{sup −}, and SO{sub 4}{sup 2−}. Therefore, the In(III) recovery can be described by a mechanism which consists of adsorption, co-precipitation, and reduction and was over 78% even after 3 cycles. The results confirmed that it was applicable to employ nZVI for In(III) immobilization.

Multielement determination of trace metals in river water (certified reference material, JSAC 0301-1) by high efficiency nebulization ICP-MS after 100-fold preconcentration with a chelating resin-packed minicolumn

International Nuclear Information System (INIS)

Zhu, Yanbei; Hattori, Ryota; Fujimori, Eiji; Umemura, Tomonari; Haraguchi, Hiroki

2005-01-01

The determination of 34 trace metals in a river water certified reference material (CRM), i.e. JSAC 0301-1, which was issued by the Japan Society for Analytical Chemistry in January 2004, was performed by ICP-MS with a high efficiency nebulizer after preconcentration with a laboratory-made chelating resin-packed minicolumn, with which trace metals were concentrated 100-fold from 50 mL of a river water sample to 0.5 mL of the final analysis solution. Trace metals in JSAC 0301-1 were observed in the concentration range from 19 μg L -1 of Al to 0.000053 μg L -1 of Bi. It was found that most of the concentrations of trace metals, including rare earth elements (REEs), in JSAC 0301-1 were lower than those in JAC 0031, which was also a previously issued CRM prepared with water from the same river as that of JSAC 0301-1. The low concentrations of trace metals in JSAC 0301-1 might be attributed to the fact that there was heavy rain before collecting the original water sample to prepare the present CRM. Furthermore, the REE distribution patterns of JSAC 0301-1, JAC 0031 and the average values of river water samples in Japan were parallel to each other. These results indicate that the distributions of REEs in JSAC 0301-1 and JAC 0031 were the typical ones of river water samples in Japan. (author)

Mechanical alloying of a hydrogenation catalyst used for the remediation of contaminated compounds

Science.gov (United States)

Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Geiger, Cherie L. (Inventor); Aitken, Brian S. (Inventor)

2012-01-01

A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. Preferably, the hydrogenation catalyst is a bimetallic particle including zero-valent metal particles coated with a catalytic material. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts.

RuO2-TiO2 mixed oxides prepared from the hydrolysis of the metal alkoxides

International Nuclear Information System (INIS)

Osman, Julian R.; Crayston, Joe A.; Pratt, Allin; Richens, David T.

2008-01-01

The hydrolysis of ruthenium alkoxide/titanium tetraethoxide mixtures to gels and powders containing 30-40 mol% Ru was investigated. Basic or neutral conditions led to powders consisting of 2-10 nm diameter crystalline RuO 2 nanoparticles embedded in a matrix of crystalline (anatase) and amorphous TiO 2 . Acid hydrolysis conditions gave gels containing smaller, amorphous RuO 2 nanoparticles (1-3 nm). In all samples the RuO 2 nanoparticles tended to clump into aggregates up to 0.5 μm across. Acid or neutral hydrolysis of ruthenium ethoxide gave samples which displayed lower surface Ru:Ti ratios as measured by XPS compared to the bulk (XRF), and also contained more low-valent Ru (as measured by XRF), probably due to incomplete hydrolysis of the precursors. These samples also contained more Ru metal after calcination (XRD). Calcination (450 deg. C) was accompanied by Ru-promoted combustion of organic material and led to crystalline (anatase) TiO 2 and Ti x Ru 1-x O 2 solid solution (rutile phase)

Health hazards and heavy metals accumulation by summer squash (Cucurbita pepo L.) cultivated in contaminated soils.

Science.gov (United States)

Galal, Tarek M

2016-07-01

The present study was carried out to investigate the heavy metal concentration accumulated by summer squash cultivated in contaminated soil and their health hazards for public consumers at south Cairo Province, Egypt. Soil and plants were sampled from contaminated and reference farms, using 1 m(2) quadrats, for biomass estimation and nutrient analysis. The daily intake of metals (DIM) and health risk index (HRI) were estimated. Significant differences in soil variables (except As) between contaminated and reference sites were recognized. Summer squash showed remarkable reduction in fresh and dry biomass, fruit production, and photosynthetic pigments under pollution stress. The inorganic and organic nutrients in the aboveground and belowground parts showed significant reduction in contaminated site. In addition, higher concentrations of heavy metals were accumulated in the edible parts and roots more than shoots. The bioaccumulation factor of summer squash for investigated metals was greater than 1, while the translocation factor did not exceed unity in both contaminated and reference sites. The DIM for all investigated metals in the reference site and in the contaminated site (except Fe and Mn) did not exceed 1 in both adults and children. However, HRI of Ni and Mn in the reference site and Pb, Cd, Cu, Ni, Fe, Mn, and Zn in the contaminated one exceeded unity indicating great potential to pose health risk to the consumers. The author recommends that people living in the contaminated area should not eat large quantities of summer squash, so as to avoid excess accumulation of heavy metals in their bodies.

The impact of zero-valent iron nanoparticles upon soil microbial communities is context dependent.

Science.gov (United States)

Pawlett, Mark; Ritz, Karl; Dorey, Robert A; Rocks, Sophie; Ramsden, Jeremy; Harris, Jim A

2013-02-01

Nanosized zero-valent iron (nZVI) is an effective land remediation tool, but there remains little information regarding its impact upon and interactions with the soil microbial community. nZVI stabilised with sodium carboxymethyl cellulose was applied to soils of three contrasting textures and organic matter contents to determine impacts on soil microbial biomass, phenotypic (phospholipid fatty acid (PLFA)), and functional (multiple substrate-induced respiration (MSIR)) profiles. The nZVI significantly reduced microbial biomass by 29 % but only where soil was amended with 5 % straw. Effects of nZVI on MSIR profiles were only evident in the clay soils and were independent of organic matter content. PLFA profiling indicated that the soil microbial community structure in sandy soils were apparently the most, and clay soils the least, vulnerable to nZVI suggesting a protective effect imparted by clays. Evidence of nZVI bactericidal effects on Gram-negative bacteria and a potential reduction of arbuscular mycorrhizal fungi are presented. Data imply that the impact of nZVI on soil microbial communities is dependent on organic matter content and soil mineral type. Thereby, evaluations of nZVI toxicity on soil microbial communities should consider context. The reduction of AM fungi following nZVI application may have implications for land remediation.

Zero-valent iron pretreatment for detoxifying iodine in liquid crystal display (LCD) manufacturing wastewater

International Nuclear Information System (INIS)

Lee, J.W.; Cha, D.K.; Oh, Y.K.; Ko, K.B.; Song, J.S.

2009-01-01

This study investigated reductive transformation of iodine by zero-valent iron (ZVI), and the subsequent detoxification of iodine-laden wastewater. ZVI completely reduced aqueous iodine to non-toxic iodide. Respirometric bioassay illustrated that the presence of iodine increase the lag phase before the onset of oxygen consumption. The length of lag phase was proportional to increasing iodine dosage. The reduction products of iodine by ZVI did not exhibit any inhibitory effect on the biodegradation. The cumulative biological oxidation associated with iodine toxicity was closely fitted to Gompertz model. When iodine-laden wastewater was continuously fed to a bench-scale activated sludge unit, chemical oxygen demand (COD) removal efficiencies decreased from above 90% to below 80% along with a marked decrease in biomass concentration. On the other hand, the COD removal efficiency and biomass concentration remained constant in the integrated ZVI-activated sludge system. Respirometric bioassay with real iodine-laden LCD manufacturing wastewater demonstrated that ZVI was effective for detoxifying iodine and consequently enhancing biodegradability of wastewater. This result suggested that ZVI pretreatment may be a feasible option for the removal of iodine in LCD processing wastewater, instead of more costly processes such as adsorption and chemical oxidation, which are commonly in the iodine-laden LCD wastewater treatment facility

Hydrolysis of metal ions. Vol. 1 and 2

Energy Technology Data Exchange (ETDEWEB)

Brown, Paul L. [Geochem Australia, Kiama, NSW (Australia); Ekberg, Christian [Chalmers Univ. of Technology, Goeteborg (Sweden). Nuclear Chemistry/Industrial Materials Recycling

2016-07-01

Filling the need for a comprehensive treatment that covers the theory, methods and the different types of metal ion complexes with water (hydrolysis), this handbook and ready reference is authored by a nuclear chemist from academia and an industrial geochemist. The book includes both cation and anion complexes, and approaches the topic of metal ion hydrolysis by first covering the background, before proceeding with an overview of the dissociation of water and then all different metal-water hydrolysis complexes and compounds. A must-have for scientists in academia and industry working on this interdisciplinary topic.

Influence of elevated alkalinity and natural organic matter (NOM) on tissue-specific metal accumulation and reproductive performance in fathead minnows during chronic, multi-trophic exposures to a metal mine effluent.

Science.gov (United States)

Ouellet, Jacob D; Dubé, Monique G; Niyogi, Som

2013-09-01

Metal bioavailability in aquatic organisms is known to be influenced by various water chemistry parameters. The present study examined the influence of alkalinity and natural organic matter (NOM) on tissue-specific metal accumulation and reproductive performance of fathead minnows (Pimephales promelas) during environmentally relevant chronic exposures to a metal mine effluent (MME). Sodium bicarbonate (NaHCO3) or NOM (as commercial humic acid) were added to a Canadian MME [45 percent process water effluent (PWE)] in order to evaluate whether increases in alkalinity (3-4 fold) or NOM (~1.5-3mg/L dissolved organic carbon) would reduce metal accumulation and mitigate reproductive toxicity in fathead minnows during a 21-day multi-trophic exposure. Eleven metals (barium, boron, cobalt, copper, lithium, manganese, molybdenum, nickel, rubidium, selenium, and strontium) were elevated in the 45 percent PWE relative to the reference water. Exposure to the unmodified 45 percent PWE resulted in a decrease of fathead minnow egg production (~300 fewer eggs/pair) relative to the unmodified reference water, over the 21-day exposure period. Water chemistry modifications produced a modest decrease in free ion activity of some metals (as shown by MINTEQ, Version 3) in the 45 percent PWE exposure water, but did not alter the metal burden in the treatment-matched larval Chironomus dilutus (the food source of fish during exposure). The tissue-specific metal accumulation increased in fish exposed to the 45 percent PWE relative to the reference water, irrespective of water chemistry modifications, and the tissue metal concentrations were found to be similar between fish in the unmodified and modified 45 percent PWE (higher alkalinity or NOM) treatments. Interestingly however, increased alkalinity and NOM markedly improved fish egg production both in the reference water (~500 and ~590 additional eggs/pair, respectively) and 45 percent PWE treatments (~570 and ~260 additional eggs

TREATMENT OF ARSENIC AND METALS IN GROUND WATER USING A COMPOST/ZVI PRB

Science.gov (United States)

A pilot permeable reactive barrier (PRB) consisting of a mixture of 30% yard waste compost, 20% zero-valent iron (ZVI), 5% limestone and 45% pea gravel by volume was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The pilo...

Digitally Milled Metal Framework for Fixed Complete Denture with Metal Occlusal Surfaces: A Design Concept.

Science.gov (United States)

AlBader, Bader; AlHelal, Abdulaziz; Proussaefs, Periklis; Garbacea, Antonela; Kattadiyil, Mathew T; Lozada, Jaime

Implant-supported fixed complete dentures, often referred to as hybrid prostheses, have been associated with high implant survival rates but also with a high incidence of mechanical prosthetic complications. The most frequent of these complications have been fracture and wear of the veneering material. The proposed design concept incorporates the occlusal surfaces of the posterior teeth as part of a digital milled metal framework by designing the posterior first molars in full contour as part of the framework. The framework can be designed, scanned, and milled from a titanium blank using a milling machine. Acrylic resin teeth can then be placed on the framework by conventional protocol. The metal occlusal surfaces of the titanium-countered molars will be at centric occlusion. It is hypothesized that metal occlusal surfaces in the posterior region may reduce occlusal wear in these types of prostheses. When the proposed design protocol is followed, the connection between the metal frame and the cantilever part of the prosthesis is reinforced, which may lead to fewer fractures of the metal framework.

Mobile heavy metal fractions in soils

International Nuclear Information System (INIS)

Horak, O.; Kamel, A.A.; Ecker, S.; Benetka, E.; Rebler, R.; Lummerstorfer, E.; Kandeler, E.

1994-01-01

A long term outdoor experiment was conducted in plastic containers (50 litres) with three soils, contaminated by increasing concentrations of zinc, copper, nickel, cadmium and vanadium. The aim of the study was to investigate the influence of heavy metal contamination on soil microbial processes as well as the accumulation of heavy metals in plants. Spring barley, followed by winter endive were grown as experimental crops in a first vegetation period, while spring wheat was grown during the second year. The soil microbial activities, indicated by arylsulfatase, dehydrogenase, and substrate-induced respiration, decreased with increasing heavy metal contamination. Significant correlations were observed between the inhibition of soil microorganisms and the easily mobilizable heavy metal fractions of soils, extracted by a solution of 1 M ammoniumacetate at pH = 7. The heavy metal accumulation in vegetative and generative parts of the crop plants also showed a good agreement with mobilizable soil fractions. The results of the experiment indicate, that the extraction with ammoniumacetate can be used as a reference method for determination of tolerable heavy metal concentrations in soils. (authors)

Ternary alkali-metal and transition metal or metalloid acetylides as alkali-metal intercalation electrodes for batteries

Science.gov (United States)

Nemeth, Karoly; Srajer, George; Harkay, Katherine C; Terdik, Joseph Z

2015-02-10

Novel intercalation electrode materials including ternary acetylides of chemical formula: A.sub.nMC.sub.2 where A is alkali or alkaline-earth element; M is transition metal or metalloid element; C.sub.2 is reference to the acetylide ion; n is an integer that is 0, 1, 2, 3 or 4 when A is alkali element and 0, 1, or 2 when A is alkaline-earth element. The alkali elements are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). The alkaline-earth elements are Berilium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). M is a transition metal that is any element in groups 3 through 12 inclusive on the Periodic Table of Elements (elements 21 (Sc) to element 30 (Zn)). In another exemplary embodiment, M is a metalloid element.

Machining of Metal Matrix Composites

CERN Document Server

2012-01-01

Machining of Metal Matrix Composites provides the fundamentals and recent advances in the study of machining of metal matrix composites (MMCs). Each chapter is written by an international expert in this important field of research. Machining of Metal Matrix Composites gives the reader information on machining of MMCs with a special emphasis on aluminium matrix composites. Chapter 1 provides the mechanics and modelling of chip formation for traditional machining processes. Chapter 2 is dedicated to surface integrity when machining MMCs. Chapter 3 describes the machinability aspects of MMCs. Chapter 4 contains information on traditional machining processes and Chapter 5 is dedicated to the grinding of MMCs. Chapter 6 describes the dry cutting of MMCs with SiC particulate reinforcement. Finally, Chapter 7 is dedicated to computational methods and optimization in the machining of MMCs. Machining of Metal Matrix Composites can serve as a useful reference for academics, manufacturing and materials researchers, manu...

Molecular and ionic mimicry and the transport of toxic metals

Science.gov (United States)

Bridges, Christy C.; Zalups, Rudolfs K.

2008-01-01

Despite many scientific advances, human exposure to, and intoxication by, toxic metal species continues to occur. Surprisingly, little is understood about the mechanisms by which certain metals and metal-containing species gain entry into target cells. Since there do not appear to be transporters designed specifically for the entry of most toxic metal species into mammalian cells, it has been postulated that some of these metals gain entry into target cells, through the mechanisms of ionic and/or molecular mimicry, at the site of transporters of essential elements and/or molecules. The primary purpose of this review is to discuss the transport of selective toxic metals in target organs and provide evidence supporting a role of ionic and/or molecular mimicry. In the context of this review, molecular mimicry refers to the ability of a metal ion to bond to an endogenous organic molecule to form an organic metal species that acts as a functional or structural mimic of essential molecules at the sites of transporters of those molecules. Ionic mimicry refers to the ability of a cationic form of a toxic metal to mimic an essential element or cationic species of an element at the site of a transporter of that element. Molecular and ionic mimics can also be sub-classified as structural or functional mimics. This review will present the established and putative roles of molecular and ionic mimicry in the transport of mercury, cadmium, lead, arsenic, selenium, and selected oxyanions in target organs and tissues. PMID:15845419

Molecular and ionic mimicry and the transport of toxic metals

International Nuclear Information System (INIS)

Bridges, Christy C.; Zalups, Rudolfs K.

2005-01-01

Despite many scientific advances, human exposure to, and intoxication by, toxic metal species continues to occur. Surprisingly, little is understood about the mechanisms by which certain metals and metal-containing species gain entry into target cells. Since there do not appear to be transporters designed specifically for the entry of most toxic metal species into mammalian cells, it has been postulated that some of these metals gain entry into target cells, through the mechanisms of ionic and/or molecular mimicry, at the site of transporters of essential elements and/or molecules. The primary purpose of this review is to discuss the transport of selective toxic metals in target organs and provide evidence supporting a role of ionic and/or molecular mimicry. In the context of this review, molecular mimicry refers to the ability of a metal ion to bond to an endogenous organic molecule to form an organic metal species that acts as a functional or structural mimic of essential molecules at the sites of transporters of those molecules. Ionic mimicry refers to the ability of a cationic form of a toxic metal to mimic an essential element or cationic species of an element at the site of a transporter of that element. Molecular and ionic mimics can also be sub-classified as structural or functional mimics. This review will present the established and putative roles of molecular and ionic mimicry in the transport of mercury, cadmium, lead, arsenic, selenium, and selected oxyanions in target organs and tissues

Improved inventory for heavy metal emissions from stationary combustion plants

DEFF Research Database (Denmark)

Nielsen, Malene; Nielsen, Ole-Kenneth; Hoffmann, Leif

On behalf of the Ministry of the Environment DCE at Aarhus University annually reports heavy metals (HM) emissions to the UNECE CLRTAP (United Nations Economic Commission for Europe Convention on Long-Range Transboundary Air Pollution). This report presents updated heavy metal emission factors......-2009. The report also include methodology, references and an uncertainty estimate. In Denmark, stationary combustion plants are among the most important emission sources for heavy metals. Emissions of all heavy metals have decreased considerably (73 % - 92 %) since 1990. The main HM emission sources are coal...

Comparison of Structurally–Related Alkoxide, Amine, and Thiolate–Ligated MII (M= Fe, Co) Complexes: the Influence of Thiolates on the Properties of Biologically Relevant Metal Complexes

Science.gov (United States)

Brines, Lisa M.; Villar-Acevedo, Gloria; Kitagawa, Terutaka; Swartz, Rodney D.; Lugo-Mas, Priscilla; Kaminsky, Werner; Benedict, Jason B.; Kovacs, Julie A.

2009-01-01

Mechanistic pathways of metalloenzymes are controlled by the metal ion’s electronic and magnetic properties, which are tuned by the coordinated ligands. The functional advantage gained by incorporating cysteinates into the active site of non-heme iron enzymes such as superoxide reductase (SOR) is not entirely understood. Herein we compare the structural and redox properties of a series of structurally–related thiolate, alkoxide, and amine–ligated Fe(II) complexes in order to determine how the thiolate influences properties critical to function. Thiolates are shown to reduce metal ion Lewis acidity relative to alkoxides and amines, and have a strong trans influence thereby helping to maintain an open coordination site. Comparison of the redox potentials of the structurally analogous compounds described herein indicates that alkoxide ligands favor the higher-valent Fe3+ oxidation state, amine ligands favor the reduced Fe2+ oxidation state, and thiolates fall somewhere in between. These properties provide a functional advantange for substrate reducing enzymes in that they provide a site at the metal ion for substrate to bind, and a moderate potential that facilitates both substrate reduction, and regeneration of the catalytically active reduced state. Redox potentials for structurally–related Co(II) complexes are shown to be cathodically–shifted relative to their Fe(II) analogues, making them ineffective reducing agents for substrates such as superoxide. PMID:21731109

Aminoclay-templated nanoscale zero-valent iron (nZVI) synthesis for efficient harvesting of oleaginous microalga, Chlorella sp. KR-1

DEFF Research Database (Denmark)

Lee, Young-Chul; Lee, Kyubock; Hwang, Yuhoon

2014-01-01

Synthesis of aminoclay-templated nanoscale zero-valent iron (nZVI) for efficient harvesting of oleaginous microalgae was demonstrated. According to various aminoclay loadings (0, 0.25, 0.5, 1.0, 2.5, 5.0, and 7.5 aminoclay/nZVI ratios), the stability of nZVI was investigated as a function......ZVI composite (ratio 1.0) exhibited a highly positively charged surface (~+40 mV) and a ferromagnetic property (~30 emu/g). On the basis of these characteristics, oleaginous Chlorella sp. KR-1 was harvested within 3 min at a > 20 g/L loading under a magnetic field. In a scaled-up (24L) microalga harvesting...... process using magnetic rods, microalgae were successfully collected by attachment to the magnetic rods or by precipitation. It is believed that this approach, thanks to the recyclability of aminoclay-nZVI composites, can be applied in a continuous harvesting mode....

GROUND WATER ARSENIC AND METALS TREATMENT USING A COMBINATION COMPOST-ZVI PRB (ABSTRACT ONLY)

Science.gov (United States)

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The PRB is designed to treat arsenic an...

Metal assessment in sediments from the Guarapiranga Reservoir

Energy Technology Data Exchange (ETDEWEB)

Coutinho, Suellen N.; Figueiredo, Ana Maria G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Quináglia, Gilson A., E-mail: sncoutinho@usp.br, E-mail: anamaria@ipen.br, E-mail: gquinaglia@sp.gov.br [Companhia Ambiental do Estado de São Paulo (CETESB), São Paulo, SP (Brazil)

2017-07-01

The study of the distribution of metals in sediments is very important from the point of view of environmental pollution once the sediment concentrates metals in aquatic systems and represents a relevant contamination monitor. The analysis of sediments has been used to evaluate the quality of aquatic systems in relation to the concentration of metals. This study aimed to assess sediment contamination by metals in the Guarapiranga Reservoir. Sediment and water samples were analyzed by ICP OES (Inductively Coupled Plasma Optical Emission Spectrometry) for As, Cd, Cr, Cu, Ni, Pb and Zn and by CV AAS (Cold Vapor Atomic Absorption Spectrophotometry) for Hg. The sediment samples results were compared to TEL (Threshold Effect Level) and PEL (Probable Effect Level) guidance values and RRV (Reference Regional Values). Geoaccumulation Index (I{sub geo}) was calculated to evaluate metals pollution degree using reference values established for metals and metalloids in sediments from the Upper Tietê Basin and E{sub H}-pH diagrams were applied to explain chemical forms and bioavailability of toxic metals in sediment samples. In general, most of the analyzed elements exceeded TEL values and Cr, Cu and Zn exceeded RRV guidelines. The high concentrations of Cu found in this reservoir can be explained by the frequent application of CuSO{sub 4} algicide, mainly at sampling site S-03. The I{sub geo} indicated moderated polluted sediments by Zn and moderately to extremely polluted sediments by Cu, especially at S-03, in agreement with the TEL, PEL and RRV values comparison. These results may indicate potential risk of the reservoir water quality. (author)

Progress in vacuum metal extraction, refining and consolidation

International Nuclear Information System (INIS)

Sundaram, C.V.; Mukherjee, T.K.; Sharma, B.P.

1973-01-01

The unique achievements in the process metallurgy of rare metals in the past quarter century should largely be attributed to advances in vacuum technology. New standards for high purity, increasing demand for pure metals and alloys for established applications, and steady improvement in sophistication and capacity of vacuum furnaces have provided the stimulus for developing and expanding vacuum metal extraction processes, and also exploring totally new processes. The paper discusses the thermochemistry of vacuum metallurgy, carbothermic and metallothermic reduction reactions, consolidation and refining by vacuum arc melting, electron beam melting and high temperature high vacuum sintering, and ultrapurification, with special reference to the reactive and refractory metals of Group IV to VI. (author)

Potential release of in vivo trace metals from metallic medical implants in the human body: from ions to nanoparticles--a systematic analytical review.

Science.gov (United States)

Matusiewicz, Henryk

2014-06-01

Metal ion release from metallic materials, e.g. metallic alloys and pure metals, implanted into the human body in dental and orthopedic surgery is becoming a major cause for concern. This review briefly provides an overview of both metallic alloys and pure metals used in implant materials in dental and orthopedic surgery. Additionally, a short section is dedicated to important biomaterials and their corrosive behavior in both real solutions and various types of media that model human biological fluids and tissues. The present review gives an overview of analytical methods, techniques and different approaches applied to the measurement of in vivo trace metals released into body fluids and tissues from patients carrying metal-on-metal prostheses and metal dental implants. Reference levels of ion concentrations in body fluids and tissues that have been determined by a host of studies are compiled, reviewed and presented in this paper. Finally, a collection of published clinical data on in vivo released trace metals from metallic medical implants is included. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of Stabilized Zero-Valent Iron Nanoparticles on Nitrate Removal from Sandy Soil

Directory of Open Access Journals (Sweden)

F. Nooralivand

2016-02-01

Full Text Available Introduction: During the recent decades, the use of N fertilizers has undeniable development regardless of their effects on the soil and environment. Increasing nitrate ion concentration in soil solution and then, leaching it into groundwater causes increase nitrate concentration in the water and raise the risk suffering from the people to some diseases. World health organization recommended maximum concentration level for nitrate and nitrite in the drinking water 50 and 3 mg/l, respectively. There are different technologies for the removal of nitrate ions from aqueous solution. The conventional methods are ion exchange, biological denitrification, reverse osmosis and chemical reduction. Using nanoscale Fe0 particles compared to other methods of nitrate omission was preferred because of; its high surface area, more reactive, lower cost and higher efficiency. More studies on the reduction of nitrate by zero-valent iron nanoparticles have been in aqueous solutions or in the soil in batch scale. Nanoparticles surface modified with poly-electrolytes, surfactants and polymers cause colloidal stability of the particles against the forces of attraction between particles and increases nanoparticle transport in porous media. The objectives of this study were to synthesize carboxymethyl cellulose stabilized zero-valent iron nanoparticles and consideration of their application for nitrate removal from sandy soil. Materials and Methods: The nanoparticles were synthesized in a lab using borohydride reduction method and their morphological characteristics were examined via scanning electron microscopy (SEM, X-ray diffraction (XRD and Fourier Transmission Infrared Spectroscopy (FTIR. Experiments were conducted on packed sand column (40 cm length and 2.5 cm inner diameter under conditions of different nanoparticle concentration (1, 2, and 3 g1-1and high initial NO3- concentration (150, 250, and 350 mgl-1. Homogeneous soil column was filled with the wet packed

Theoretical studies of transition metal complexes with nitriles and isocyanides

International Nuclear Information System (INIS)

Kuznetsov, Maksim L

2002-01-01

Theoretical studies of transition metal complexes with nitriles and isocyanides are reviewed. The electronic structures and the nature of coordination bonds in these complexes are discussed. The correlation between the electronic structures of transition metal complexes with nitriles and isocyanides and their structural properties, spectroscopic characteristics, and reactivities are considered. The bibliography includes 121 references.

Nanotoxicity: oxidative stress mediated toxicity of metal and metal oxide nanoparticles.

Science.gov (United States)

Sarkar, Abhijit; Ghosh, Manoranjan; Sil, Parames Chandra

2014-01-01

Metal and metal oxide nanoparticles are often used as industrial catalysts or to improve product's functional properties. Recent advanced nanotechnology have been expected to be used in various fields, ranging from sensors, environmental remediation to biomedicine, medical biology and imaging, etc. However, the growing use of nanoparticles has led to their release into environment and increased levels of these particles at nearby sites or the surroundings of their manufacturing factories become obvious. The toxicity of metal and metal oxide nanoparticles on humans, animals, and certainly to the environment has become a major concern to our community. However, controversies still remain with respect to the toxic effects and the mechanisms of these nanoparticles. The scientific community now feels that an understanding of the toxic effects is necessary to handle these nanoparticles and their use. A new discipline, named nanotoxicology, has therefore been developed that basically refers to the study of the interactions of nanoparticles with biological systems and also measures the toxicity level related to human health. Nanoparticles usually generate reactive oxygen species to a greater extent than micro-sized particles resulting in increased pro-inflammatory reactions and oxidative stress via intracellular signaling pathways. In this review, we mainly focus on the routes of exposure of some metal and metal oxide nanoparticles and how these nanoparticles affect us or broadly the cells of our organs. We would also like to discuss the responsible mechanism(s) of the nanoparticle-induced reactive oxygen species mediated organ pathophysiology. A brief introduction of the characterization and application of these nanoparticles has also been included in the article.

Immunogenicity of a 23-valent pneumococcal polysaccharide vaccine in elderly residents of a long-term care facility

Directory of Open Access Journals (Sweden)

M. Teresa Valenzuela B.

Full Text Available S. pneumoniae is a significant cause of community-acquired pneumonia in the elderly, and accounts for the majority of the pneumonia deaths among the elderly. We conducted this randomized double-blind study to evaluate the immune response to a 23-valent pneumococcal polysaccharide vaccine and the persistence of antibodies two years after the vaccination in an elderly population in Santiago, Chile. A total of 118 elderly nursing home residents received either the pneumococcal or a tetanus control vaccine. Serum samples were taken at enrolment, at two months, and at two years post-vaccination. Pre-vaccination anti-pneumococcal antibody geometric mean concentrations (GMC were similar in both study groups, with increased levels of antibodies found only against serotype 14. The pneumococcal vaccine was highly immunogenic at 2 months, and titers remained high two years after the vaccination for the 10 serotypes studied in this elderly population. The results thus support the benefits of this pneumococcal vaccine in this elderly population who are at increased risk of invasive pneumococcal disease.

Reductive trapping of [(OC){sub 5}W-W(CO){sub 5}]{sup 2-} in a mixed-valent Sm{sup II/III} calix[4]pyrrolide sandwich

Energy Technology Data Exchange (ETDEWEB)

Deacon, Glen B.; Guo, Zhifang [School of Chemistry, Monash University, VIC (Australia); Junk, Peter C.; Wang, Jun [College of Science and Engineering, James Cook University, Townsville, QLD (Australia)

2017-07-10

Reduction of tungsten hexacarbonyl by the divalent samarium(II) complex [Sm{sub 2}(N{sub 4}Et{sub 8})(thf){sub 4}] ((N{sub 4}Et{sub 8}){sup 4-}=meso-octaethylcalix[4]pyrrolide) in toluene at ambient temperature gave the remarkable heteronuclear mixed-valent samarium(II/III)/tungsten complex [{(thf)_2Sm"I"I(N_4Et_8)Sm"I"I"I(thf)}{sub 2}{(μ-OC)_2W_2(CO)_8}], which features the trapping of a rare [W{sub 2}(CO){sub 10}]{sup 2-} anion with an unsupported W-W bond. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Enhanced chitosan beads-supported Fe(0)-nanoparticles for removal of heavy metals from electroplating wastewater in permeable reactive barriers.

Science.gov (United States)

Liu, Tingyi; Yang, Xi; Wang, Zhong-Liang; Yan, Xiaoxing

2013-11-01

The removal of heavy metals from electroplating wastewater is a matter of paramount importance due to their high toxicity causing major environmental pollution problems. Nanoscale zero-valent iron (NZVI) became more effective to remove heavy metals from electroplating wastewater when enhanced chitosan (CS) beads were introduced as a support material in permeable reactive barriers (PRBs). The removal rate of Cr (VI) decreased with an increase of pH and initial Cr (VI) concentration. However, the removal rates of Cu (II), Cd (II) and Pb (II) increased with an increase of pH while decreased with an increase of their initial concentrations. The initial concentrations of heavy metals showed an effect on their removal sequence. Scanning electron microscope images showed that CS-NZVI beads enhanced by ethylene glycol diglycidyl ether (EGDE) had a loose and porous surface with a nucleus-shell structure. The pore size of the nucleus ranged from 19.2 to 138.6 μm with an average aperture size of around 58.6 μm. The shell showed a tube structure and electroplating wastewaters may reach NZVI through these tubes. X-ray photoelectron spectroscope (XPS) demonstrated that the reduction of Cr (VI) to Cr (III) was complete in less than 2 h. Cu (II) and Pb (II) were removed via predominant reduction and auxiliary adsorption. However, main adsorption and auxiliary reduction worked for the removal of Cd (II). The removal rate of total Cr, Cu (II), Cd (II) and Pb (II) from actual electroplating wastewater was 89.4%, 98.9%, 94.9% and 99.4%, respectively. The findings revealed that EGDE-CS-NZVI-beads PRBs had the capacity to remediate actual electroplating wastewater and may become an effective and promising technology for in situ remediation of heavy metals. Copyright © 2013 Elsevier Ltd. All rights reserved.

Estimating the cost-effectiveness profile of a universal vaccination programme with a nine-valent HPV vaccine in Austria.

Science.gov (United States)

Boiron, L; Joura, E; Largeron, N; Prager, B; Uhart, M

2016-04-16

HPV is a major cancer-causing factor in both sexes in the cervix, vulva, vagina, anus, penis, oropharynx as well as the causal factor in other diseases such as genital warts and recurrent respiratory papillomatis. In the context of the arrival of a nonavalent HPV vaccine (6/11/16/18/31/33/45/52/58), this analysis aims to estimate the public health impact and the incremental cost-effectiveness of a universal (girls and boys) vaccination program with a nonavalent HPV vaccine as compared to the current universal vaccination program with a quadrivalent HPV vaccine (6/11/16/18), in Austria. A dynamic transmission model including a wide range of health and cost outcomes related to cervical, anal, vulvar, vaginal diseases and genital warts was calibrated to Austrian epidemiological data. The clinical impact due to the 5 new types was included for cervical and anal diseases outcomes only. In the base case, a two-dose schedule, lifelong vaccine type-specific protection and a vaccination coverage rate of 60% and 40% for girls and boys respectively for the 9-year old cohorts were assumed. A cost-effectiveness threshold of €30,000/QALY-gained was considered. Universal vaccination with the nonavalent vaccine was shown to reduce the incidence of HPV16/18/31/33/45/52/58 -related cervical cancer by 92%, the related CIN2/3 cases by 96% and anal cancer by 83% and 76% respectively in females and males after 100 years, relative to 75%, 76%, 80% and 74% with the quadrivalent vaccine, respectively. Furthermore, the nonavalent vaccine was projected to prevent an additional 14,893 cases of CIN2/3 and 2544 cases of cervical cancer, over 100 years. Depending on the vaccine price, the strategy was shown to be from cost-saving to cost-effective. The present evaluation showed that vaccinating 60% of girls and 40% of boys aged 9 in Austria with a 9-valent vaccine will substantially reduce the incidence of cervical cancer, CIN and anal cancer compared to the existing strategy. The vaccination

The role of heavy metals and polychlorinated biphenyls (PCBs) in the oncogenesis of head and neck tumors and thyroid diseases: a pilot study.

Science.gov (United States)

Petrosino, V; Motta, G; Tenore, G; Coletta, M; Guariglia, A; Testa, D

2018-04-01

Previous literature has highlighted the mechanisms of molecular toxicity induced by substances such as arsenic, cadmium, chromium, nickel, lead, barium and PCBs. The research was carried out on 20 volunteers, all the patients gave their consent to the research: the aim of the study was to evaluate the presence of metals and PCBs in these different matrices (blood and hair), correlating the biochemical data to pathological conditions present, and also to the area in which patients resided. Various quantitative determinations were carried out on samples of blood and hair for 14 heavy metals and on blood samples for 12 PCBs. For the 11 patients the results indicated that blood levels for half of the 14 displayed heavy metals measured considerably higher compared to the reference values, whilst the levels measured in hair evidenced some positive values significantly higher than the maximum reference. Of the 12 PCBs assayed in blood some showed higher positive values compared to the maximum tabular reference (although there is no clear reference quantified in the WHO-2005 report). In the 9 healthy patients heavy metals in the blood were within the expected target range, with those showing positive results (≤ 3 out of 14 heavy metals for each patient) having values only slightly higher than the reference maximum. The levels of 14 heavy metals measured in hair were below thresholds, and levels for the 12 PCBs measured in blood showed negativity or positivity with values close to the minimum benchmarks. The analyses carried out on biological matrices have uncovered important and significant differences between healthy and unhealthy subjects, both qualitative and quantitative differences with respect to heavy metals and PCBs. All patients with head and neck cancer enlisted for the study had heavy metal and PCB blood levels at least twice the maximum reference level. The levels of heavy metals in hair were at least double the maximum reference. In contrast, all healthy

Bioindication of atmospheric trace metals - With special references to megacities

International Nuclear Information System (INIS)

Markert, Bernd; Wuenschmann, Simone; Fraenzle, Stefan; Graciana Figueiredo, Ana Maria; Ribeiro, Andreza P.; Wang Meie

2011-01-01

After considering the particular problems of atmospheric pollution in megacities, i.e. agglomerations larger than 5 mio. inhabitants, with urbanization of World's population going on steadily, possibilities of active biomonitoring by means of green plants are discussed. Based on specific definitions of active and passive bioindication the chances of monitoring heavy metals in Sao Paulo megacity were demonstrated (first results published before). This is to show that there is need for increased use of bioindication to tackle the particular problems of megacities concerning environmental 'health', the data to be processed according to the Multi-Markered-Bioindication-Concept (MMBC). Comparison to other work shows this approach to be reasonable. - Highlights: → Chemical Pollution. → Bioindication. → Multi-Markered-Bioindication-Concept (MMBC). → Mega cities. - Bioindication is a relevant technique for observing the atmospheric deposition of chemical elements of the environment in megacities.

Quantifying wave propagation over a corrugated metal using 5 dBi antennas

CSIR Research Space (South Africa)

Nkosi, MC

2015-09-01

Full Text Available corrugated metal of a shipping container and also in a free space. The free space measurement is used as a reference point to study the influence of the metal on the wave propagation. The transmission coefficient measured over the shipping container...

Tris[bis(trimethylsilyl)amido]uranium: Compounds with tri-, tetra-, and penta-valent uranium

International Nuclear Information System (INIS)

Stewart, J.L.

1988-04-01

This trivalent uranium compound, serves as a precursor to new tri-, tetra-, and penta-valent uranium species. The geometry about the U atom is pyramidal. Lewis-base coordination compounds of U[N(SiMe 3 ) 2 ] 3 with a one-to-one- ratio of Lewis base to uranium were isolated with pyridine, 4-dimethylamino-pyridine, 2,6-Me 2 -C 6 H 3 NC, and TPO. Two-to-one coordination compounds were obtained with t-butylnitrile and t-butylisocyanide. Compounds with more sterically demanding bases could not be isolated. The expected decrease in U-N(SiMe 3 ) 2 bond length with increase in oxidation state is not observed. Reaction of ClU[N(SiMe 3 ) 2 ] 3 and Li[NH(p-tolyl)] yields the uranium (IV) dimer, U 2 [N(SiMe 3 ) 2 ] 4 [μ-N(p-tolyl)] 2 . Reaction with 2,4,6-triemethylaniline produces a dimer. Analogous substitution products could not be obtained with aniline or p-toluidine. t-Bu 3 CO/sup /minus//, t-Bu 2 CHO/sup /minus//, and t-Bu 3 SiO/sup /minus// are used to synthesize new tetravalent, mononuclear uranium compounds. Reaction of ClU(tritox) 3 with alkyllithium reagents leads to isolation of RU(tritox) 3 . The reaction of U(ditox) 4 with MeLi affords the addition product U(ditox) 4 (Me)Li, whose crystal structure is described. Preparation of uranium silox compounds is reported. 97 refs., 26 figs., 39 tabs

Safety of 13-valent pneumococcal conjugate vaccine in infants and children: meta-analysis of 13 clinical trials in 9 countries.

Science.gov (United States)

Thompson, Allison; Gurtman, Alejandra; Patterson, Scott; Juergens, Christine; Laudat, France; Emini, Emilio A; Gruber, William C; Scott, Daniel A

2013-10-25

Meta-analyses enable summarization and interpretation of data across clinical trials. When applied to safety data they allow for detection of rare events. Recently, a 13-valent pneumococcal conjugate vaccine (PCV13) was approved in multiple countries worldwide for routine immunization of infants and young children. This meta-analysis was conducted to identify potentially clinically important rare safety events associated with PCV13. To summarize the safety of PCV13 compared with 7-valent pneumococcal conjugate vaccine (PCV7) administered to infants and toddlers. A meta-analysis was performed of integrated safety data from 13 infant studies (PCV13 n=4729 and PCV7 n=2760) conducted in 9 North American, European, and Asian countries. Local reactions at the vaccine injection site and systemic events were collected for 4-7 days after each dose into electronic diaries. Adverse events (AEs) were collected after each vaccination. Overall, rates of local reactions after any dose of the infant series were similar between PCV13 and PCV7 groups: tenderness (46.7% vs 44.8%, respectively); swelling (28.5% vs 26.9%); and redness (36.4% vs 33.9%). After the toddler dose, tenderness was significantly higher among PCV7 subjects than PCV13 subjects (54.4% vs 48.8%; P=0.005). Frequencies of fever (≥38°C) were similar in both groups and mostly mild (≤39°C); incidence of moderate fever (>39°C to ≤40°C) with PCV13 was ≤2.8% after any infant dose and 5.0% after the toddler dose, compared with ≤2.6% and 7.3%, respectively, with PCV7. Fever >40°C was uncommon in both groups. Frequencies of decreased appetite, irritability, and sleep disturbances were similar in both groups. AEs were the types of conditions and symptoms expected in infants and children, and clinically significant differences between vaccine groups were not observed. PCV13 has a favorable safety profile similar to that of PCV7, a vaccine for which there is >10 years clinical experience. Copyright © 2013

Theoretical Modelling of Immobilization of Cadmium and Nickel in Soil Using Iron Nanoparticles

Directory of Open Access Journals (Sweden)

Vaidotas Danila

2017-09-01

Full Text Available Immobilization using zero valent using iron nanoparticles is a soil remediation technology that reduces concentrations of dissolved contaminants in soil solution. Immobilization of heavy metals in soil can be achieved through heavy metals adsorption and surface complexation reactions. These processes result in adsorption of heavy metals from solution phase and thus reducing their mobility in soil. Theoretical modelling of heavy metals, namely, cadmium and nickel, adsorption using zero valent iron nanoparticles was conducted using Visual MINTEQ. Adsorption of cadmium and nickel from soil solutions were modelled separately and when these metals were dissolved together. Results have showed that iron nanoparticles can be successfully applied as an effective adsorbent for cadmium and nickel removal from soil solution by producing insoluble compounds. After conducting the modelling of dependences of Cd+2 and Ni+2 ions adsorption on soil solution pH using iron nanoparticles, it was found that increasing pH of solution results in the increase of these ions adsorption. Adsorption of cadmium reached approximately 100% when pH ≥ 8.0, and adsorption of nickel reached approximately 100% when pH ≥ 7.0. During the modelling, it was found that adsorption of heavy metals Cd and Ni mostly occur, when one heavy metal ion is chemically adsorbed on two sorption sites. During the adsorption modelling, when Cd+2 and Ni+2 ions were dissolved together in acidic phase, it was found that adsorption is slightly lower than modelling adsorption of these metals separately. It was influenced by the competition of Cd+2 and Ni+2 ions for sorption sites on the surface of iron nanoparticles.

Ferro zero: uma nova abordagem para o tratamento de águas contaminadas com compostos orgânicos poluentes Zero-valent iron: a new approach for treatment of waters contamined with organic pollutants

OpenAIRE

Wellington S. Pereira; Renato S. Freire

2005-01-01

Anthropogenic pollution of groundwater and surface water has become a very serious environmental problem around the world. A wide range of toxic pollutants is recalcitrant to the conventional treatment methods, thus there is much interest in the development of more efficient remediation processes. Degradation of organic pollutants by zero-valent iron is one of the most promising approaches for water treatment, mainly because it is of low cost, easy to obtain and effective. After a general int...

Final efficacy, immunogenicity, and safety analyses of a nine-valent human papillomavirus vaccine in women aged 16-26 years

DEFF Research Database (Denmark)

Huh, Warner K; Joura, Elmar A; Giuliano, Anna R

2017-01-01

BACKGROUND: Primary analyses of a study in young women aged 16-26 years showed efficacy of the nine-valent human papillomavirus (9vHPV; HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58) vaccine against infections and disease related to HPV 31, 33, 45, 52, and 58, and non-inferior HPV 6, 11, 16, and 18...... antibody responses when compared with quadrivalent HPV (qHPV; HPV 6, 11, 16, and 18) vaccine. We aimed to report efficacy of the 9vHPV vaccine for up to 6 years following first administration and antibody responses over 5 years. METHODS: We undertook this randomised, double-blind, efficacy, immunogenicity......, and safety study of the 9vHPV vaccine study at 105 study sites in 18 countries. Women aged 16-26 years old who were healthy, with no history of abnormal cervical cytology, no previous abnormal cervical biopsy results, and no more than four lifetime sexual partners were randomly assigned (1:1) by central...

Metal contamination of home garden soils and cultivated vegetables in the province of Brescia, Italy: Implications for human exposure

Energy Technology Data Exchange (ETDEWEB)

Ferri, Roberta [Occupational Health, University of Brescia (Italy); Hashim, Dana [Occupational and Environmental Medicine, Icahn School of Medicine at Mount Sinai, New York (United States); Smith, Donald R. [Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA (United States); Guazzetti, Stefano [Public Health Service, Reggio Emilia (Italy); Donna, Filippo [Occupational Health, University of Brescia (Italy); Ferretti, Enrica; Curatolo, Michele; Moneta, Caterina [Department of Food Chemistry, Metal Laboratory, IZSLER, Brescia (Italy); Beone, Gian Maria [Institute of Agricultural and Environmental Chemistry, Università Cattolica, Piacenza (Italy); Lucchini, Roberto G. [Occupational Health, University of Brescia (Italy); Occupational and Environmental Medicine, Icahn School of Medicine at Mount Sinai, New York (United States); Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA (United States)

2015-06-15

Background: For the past century, ferroalloy industries in Brescia province, Italy produced particulate emissions enriched in manganese (Mn), lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), iron (Fe), and aluminum (Al). This study assessed metal concentrations in soil and vegetables of regions with varying ferroalloy industrial activity levels. Methods: Home gardens (n = 63) were selected in three regions of varying ferroalloy plant activity durations in Brescia province. Total soil metal concentration and extractability were measured by X-Ray Fluorescence (XRF), aqua regia extraction, and modified Community Bureau of Reference (BCR) sequential extraction. Unwashed and washed spinach and turnips cultivated in the same gardens were analyzed for metal concentrations by flame atomic absorption spectrometry. Results: Median soil Al, Cd, Fe, Mn, Pb, and Zn concentrations were significantly higher in home gardens near ferroalloy plants compared to reference home gardens. The BCR method yielded the most mobile soil fraction (the sum of extractable metals in Fractions 1 and 2) and all metal concentrations were higher in ferroalloy plant areas. Unwashed spinach showed higher metal concentrations compared to washed spinach. However, some metals in washed spinach were higher in the reference area likely due to history of agricultural product use. Over 60% of spinach samples exceeded the 2- to 4-fold Commission of European Communities and Codex Alimentarius Commission maximum Pb concentrations, and 10% of the same spinach samples exceeded 2- to 3-fold maximum Cd concentrations set by both organizations. Turnip metal concentrations were below maximum standard reference values. Conclusions: Prolonged industrial emissions increase median metal concentrations and most soluble fractions (BCR F1 + F2) in home garden soils near ferroalloy plants. Areas near ferroalloy plant sites had spinach Cd and Pb metal concentrations several-fold above maximum standard references

Metal contamination of home garden soils and cultivated vegetables in the province of Brescia, Italy: Implications for human exposure

International Nuclear Information System (INIS)

Ferri, Roberta; Hashim, Dana; Smith, Donald R.; Guazzetti, Stefano; Donna, Filippo; Ferretti, Enrica; Curatolo, Michele; Moneta, Caterina; Beone, Gian Maria; Lucchini, Roberto G.

2015-01-01

Background: For the past century, ferroalloy industries in Brescia province, Italy produced particulate emissions enriched in manganese (Mn), lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), iron (Fe), and aluminum (Al). This study assessed metal concentrations in soil and vegetables of regions with varying ferroalloy industrial activity levels. Methods: Home gardens (n = 63) were selected in three regions of varying ferroalloy plant activity durations in Brescia province. Total soil metal concentration and extractability were measured by X-Ray Fluorescence (XRF), aqua regia extraction, and modified Community Bureau of Reference (BCR) sequential extraction. Unwashed and washed spinach and turnips cultivated in the same gardens were analyzed for metal concentrations by flame atomic absorption spectrometry. Results: Median soil Al, Cd, Fe, Mn, Pb, and Zn concentrations were significantly higher in home gardens near ferroalloy plants compared to reference home gardens. The BCR method yielded the most mobile soil fraction (the sum of extractable metals in Fractions 1 and 2) and all metal concentrations were higher in ferroalloy plant areas. Unwashed spinach showed higher metal concentrations compared to washed spinach. However, some metals in washed spinach were higher in the reference area likely due to history of agricultural product use. Over 60% of spinach samples exceeded the 2- to 4-fold Commission of European Communities and Codex Alimentarius Commission maximum Pb concentrations, and 10% of the same spinach samples exceeded 2- to 3-fold maximum Cd concentrations set by both organizations. Turnip metal concentrations were below maximum standard reference values. Conclusions: Prolonged industrial emissions increase median metal concentrations and most soluble fractions (BCR F1 + F2) in home garden soils near ferroalloy plants. Areas near ferroalloy plant sites had spinach Cd and Pb metal concentrations several-fold above maximum standard references

A Mixed-Valent Molybdenum Monophosphate with a Layer Structure: KMo 3P 2O 14

Science.gov (United States)

Guesdon, A.; Borel, M. M.; Leclaire, A.; Grandin, A.; Raveau, B.

1994-03-01

A new mixed-valent molybdenum monophosphate with a layer structure KMo 3P 2O 14 has been isolated. It crystallizes in the space group P2 1/ m with a = 8.599(2) Å, b = 6.392(2) Å, c = 10.602(1) Å, and β = 111.65(2)°. The layers [Mo 3P 2O 14] ∞ are parallel to (100) and consist of [MoPO 8] ∞ chains running along limitb→ , in which one MoO 6 octahedron alternates with one PO 4 tetrahedron. In fact, four [MoPO 8] ∞ chains share the corners of their polyhedra and the edges of their octahedra, forming [Mo 4P 4O 24] ∞ columns which are linked through MoO 5 bipyramids along limitc→. The K + ions interleaved between these layers are surrounded by eight oxygens, forming bicapped trigonal prisms KO 8. Besides the unusual trigonal bipyramids MoO 5, this structure is also characterized by a tendency to the localization of the electrons, since one octahedral site is occupied by Mo(V), whereas the other octahedral site and the trigonal bipyramid are occupied by Mo(VI). The similarity of this structure with pure octahedral layer structures suggests the possibility of generating various derivatives, and of ion exchange properties.

Metals in aerosols of the Mexico City; Metales en aerosoles de la Ciudad de Mexico

Energy Technology Data Exchange (ETDEWEB)

Reyes L, J. [Instituto Nacional de Investigaciones Nucleares, Salazar, Estado de Mexico C.P. 52045 (Mexico)

1998-07-01

The general purpose and scope of this work was to have a data base that includes enough information about the heavy metals which are disseminated in the atmospheric air in Mexico City, like it is what refers to its elements, its concentration and its particle size. For this were collected samples through collectors types: of the filters unit and the cascade impactor. Through the PIXE analysis for filters and films it was identified the presence of 20 elements in the majority of samples studied of the four seasons during the years 1993-1994. The metals were classified in two groups: those of natural origin and those of anthropogenic origin. (Author)

Removal of selenite by zero-valent iron combined with ultrasound: Se(IV) concentration changes, Se(VI) generation, and reaction mechanism.

Science.gov (United States)

Fu, Fenglian; Lu, Jianwei; Cheng, Zihang; Tang, Bing

2016-03-01

In this paper, the performance and application of zero-valent iron (ZVI) assisted by ultrasonic irradiation for the removal of selenite (Se(IV)) in wastewater was evaluated and reaction mechanism of Se(IV) with ZVI in such systems was investigated. A series of batch experiments were conducted to determine the effects of ultrasound power, pH, ZVI concentration, N2 and air on Se(IV) removal. ZVI before and after reaction with Se(IV) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that ultrasound can lead to a significant synergy in the removal of Se(IV) by ZVI because ultrasound can promote the generation of OH and accelerate the advanced Fenton process. The primary reaction products of ZVI and Se(IV) were Se(0), ferrihydrite, and Fe2O3. Copyright © 2015 Elsevier B.V. All rights reserved.

DIRECT INFUSION ESI-MS APPLIED IN THE DETECTION OF BYPRODUCTS DUE TO REDUCTIVE DEGRADATION OF ACETAMIPRID BY ZERO-VALENT IRON

Directory of Open Access Journals (Sweden)

Jean C. Cruz

2015-09-01

Full Text Available This study investigated the reductive degradation of acetamiprid (5 mg L-1 in aqueous medium (at pH 2.0 induced by zero-valent iron (50 mg. The process was monitored using high-performance liquid chromatography (HPLC to determine the degradation rate as a function of reaction time, and direct infusion electrospray ionization mass spectrometry (DI-ESI-MS to search for (and potentially characterize any possible byproducts formed during degradation. The results obtained via HPLC showed that after 60 min, the degradation of the substrate reached nearly 100% in an acidic medium, whereas the mineralization rate (as determined by total organic carbon measurements was as low as 3%. Data obtained by DI-ESI-MS showed that byproducts were formed mainly by insertions of hydrogen atoms into the nitrile, imine, and pyridine ring moieties, in addition to the observation of chlorine substitution by hydrogen replacement (hydrodechlorination reactions.

IMMUNOGENICITY AND SAFETY OF 23-VALENT POLYSACCHARIDE PNEUMOCOCCAL VACCINE IN PATIENTS WITH RHEUMATOID ARTHRITIS: RESULTS OF A TWO-YEAR FOLLOW-UP STUDY

Directory of Open Access Journals (Sweden)

M. S. Naumtseva

2016-01-01

Full Text Available Objective: to investigate the immunogenicity, safety, and clinical efficacy of 23-valent polysaccharide pneumococcal vaccine in patients with rheumatoid arthritis (RA during a two-year follow-up study.Subjects and methods. The prospective open-label comparative study enrolled 110 people, of them there were 81 (73.6% women and 29 (26.4% men at the age of 23 to 76 years, including 79 patients with RA, as well as 31 subjects without systemic inflammatory rheumatic diseases (RD (a control group. The group of RA patients exhibited a predominance of middle-aged women who had > 3 years’ disease duration and a moderate inflammatory activity (the mean value of DAS28, 4.32. 52 patients received methotrexate (MTX, 14 had Leflunomide (LEF, and 13 were treated with tumor necrosis factor-α (TNF-α inhibitors + MTX.The 23-valent polysaccharide pneumococcal vaccine Pneumo-23 (Sanofi Pasteur, France was administered in a single dose of 0.5 ml subcutaneously during continuous MTX or LEF therapy for the underlying disease or 3–4 weeks before the use of TNF-α inhibitors. Clinical examinations of the patient and conventional clinical and laboratory studies were performed during control visits (1, 3, 12, and 24 months after vaccination. Clinical effectiveness and safety were evaluated in all the patients included in the study. The serum levels of anti-pneumococcal capsular polysaccharide antibodies (Ab were measured in 72 patients with RA and in 30 individuals in the control group during a 12-month follow-up study, including in 25 patients with RA for a 24-month follow-up study by enzyme immunoassay using commercial VaccZymeTM Anti-PCP IgG Enzyme Immunoassay kits (The Binding Site Group Ltd, Birmingham, United Kingdom. Along with this, the post-immunization response coefficient was calculated for each patient as the ratio of postvaccination Ab levels during Visits 2, 3, 4, and 5 to the baseline Ab level. Results and discussion. No clinical and

Parental Attitudes and Beliefs Regarding the Nine-Valent Human Papillomavirus Vaccine.

Science.gov (United States)

Fontenot, Holly B; Domush, Vanessa; Zimet, Gregory D

2015-12-01

The purpose of the study was to explore parents' attitudes and beliefs about the nine-valent human papillomavirus vaccine (HPV9). Online focus groups were conducted in January, 2015. The U.S. national sample of parents was recruited to four groups: (1) two groups of parents of HPV unvaccinated daughters aged 9-12 years and (2) two groups of parents of vaccinated daughters aged 11-17 years. Participants were 43 parents of vaccinated daughters and 38 parents of unvaccinated daughters. Results indicated low and variable levels of knowledge about HPV, related cancers, and vaccination (e.g., parents unaware vaccine is recommended for boys). Parents were encouraged that HPV9 covered more types, and many said they want the "better" vaccine. Parents of unvaccinated girls wondered whether they should delay vaccination until HPV9 was available, whereas parents of vaccinated girls wondered whether their daughters could be revaccinated with HPV9. Concerns were related to adverse reactions and side effects, whether another new vaccine will be released after HPV9, HPV mutation (i.e., will HPV types change over time--thereby necessitating multiple vaccines?), and cost. Physician recommendation was identified as the most important facilitator of vaccination, with participants wanting providers to exhibit high levels of confidence in and knowledge about HPV vaccines. Last, parents also viewed the prospective idea of a 2-dose HPV9 vaccine as positive. HPV9 recently became available in the United States and has the potential to offer greater cancer prevention if widespread acceptance and uptake occur. Understanding parental perceptions and questions about HPV9 will be important for clinical messaging about this vaccine. Copyright © 2015 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Redox-active media for permeable reactive barriers

International Nuclear Information System (INIS)

Sivavec, T.M.; Mackenzie, P.D.; Horney, D.P.; Baghel, S.S.

1997-01-01

In this paper, three classes of redox-active media are described and evaluated in terms of their long-term effectiveness in treating TCE-contaminated groundwater in permeable reactive zones. Zero-valent iron, in the form of recycled cast iron filings, the first class, has received considerable attention as a reactive media and has been used in about a dozen pilot- and full-scale subsurface wall installations. Criteria used in selecting commercial sources of granular iron, will be discussed. Two other classes of redox-active media that have not yet seen wide use in pilot- or full-scale installations will also be described: Fe(II) minerals and bimetallic systems. Fe(II) minerals, including magnetite (Fe 3 O 4 ), and ferrous sulfide (troilite, FeS), are redox-active and afford TCE reduction rates and product distributions that suggest that they react via a reductive mechanism similar to that which operates in the FeO system. Fe(II) species within the passive oxide layer coating the iron metal may act as electron transfer mediators, with FeO serving as the bulk reductant. Bimetallic systems, the third class of redox-active media, are commonly prepared by plating a second metal onto zero-valent iron (e.g., Ni/Fe and Pd/Fe) and have been shown to accelerate solvent degradation rates relative to untreated iron metal. The long-term effectiveness of this approach, however, has not yet been determined in groundwater treatability tests. The results of a Ni-plated iron column study using site groundwater indicate that a change in reduction mechanism (to catalytic dehydrohalogenation/hydrogenation) accounts for the observed rate enhancement. A significant loss in media reactivity was observed over time, attributable to Ni catalyst deactivation or poisoning. Zero-valent iron systems have not shown similar losses in reactivity in long-term laboratory, pilot or field investigations

La2/5Ba2/5Ca1/5

Indian Academy of Sciences (India)

Unknown

2003) are well known for their antiferromagnetic beha- viour as well as for their giant magnetoresistance. Substi- tution of La by monovalent alkali or divalent alkaline earth metal ions induces ferromagnetic behaviour in these oxides. Such substitution of lower valent ions for La3+ ions results in mixed valence at the Mn site, ...

Advancing liquid metal reactor technology with nitride fuels

International Nuclear Information System (INIS)

Lyon, W.F.; Baker, R.B.; Leggett, R.D.; Matthews, R.B.

1991-08-01

A review of the use of nitride fuels in liquid metal fast reactors is presented. Past studies indicate that both uranium nitride and uranium/plutonium nitride possess characteristics that may offer enhanced performance, particularly in the area of passive safety. To further quantify these effects, the analysis of a mixed-nitride fuel system utilizing the geometry and power level of the US Advanced Liquid Metal Reactor as a reference is described. 18 refs., 2 figs., 2 tabs

Bibliography on cycling of trace metals in freshwater ecosystems

International Nuclear Information System (INIS)

LaRiviere, M.G.; Scott, A.J.; Woodfield, W.G.; Cushing, C.E.

1978-07-01

This bibliography is a listing of pertinent literature directly addressing the cycling of trace metals in freshwater ecosystems. Data on cycling, including the influences of environmental mediators, are included. 151 references

Testing of dissimilar metal welds according KTA 3201.4

International Nuclear Information System (INIS)

Giersbeck, Kai; Huenies, Gordon

2014-01-01

The amended German standard KTA 3201.4 from 2010 has triggered intensified requirements of the mechanized ultrasonic testing methodology. The report discusses the most important changes of KTA 3201.4 concerning the issues reference block, qualification of the testing methodology, testing of cladded surfaces, dissimilar metal joints, thermal conduits. The demonstration of dissimilar metal weld testing using intelligent NDT is demonstrated for the nozzles in German nuclear power plants.

Biliary drainage of the common bile duct with an enteral metal stent

NARCIS (Netherlands)

dek, Irene M.; van den Elzen, Bram D. J.; Fockens, Paul; Rauws, Erik A. J.

2009-01-01

In this case report we present an elderly patient who was referred to our hospital with recurrent episodes of cholangitis that persisted after placement of five metal stents for a distal common bile duct (CBD) stenosis. All metal stents were endoscopically removed from the CBD by forceps after

Determination of Toxic Metals in Indian Smokeless Tobacco Products

Directory of Open Access Journals (Sweden)

Dhanashri Dhaware

2009-01-01

Full Text Available This study targets the lesser-known ingredients of smokeless tobacco products, i.e., the toxic metals, in Indian brands. The metals selected in the study included lead (Pb, cadmium (Cd, arsenic (As, copper (Cu, mercury (Hg, and selenium (Se. The differential pulse anodic stripping voltammetry (DPASV technique was used for estimating the metals Pb, Cd, and Cu; square wave voltammetry for As; and the cold vapor atomic absorption technique for Hg. The resulting levels of the metals were compared to the daily consumption of the smokeless tobacco products. It was observed that almost 30% of gutkha brand samples exceeded the permissible levels of metals Pb and Cu, when compared to the provisional tolerable intake limits determined by the FAO/WHO. The reliability of data was assured by analyzing standard reference materials.

Forecasting of physicochemical properties of rare earth sesquioxides on the base of their electronic structure in condensed state using electronic computer

International Nuclear Information System (INIS)

Kutolin, S.A.; Kotyukov, V.I.; Komarova, S.N.; Smirnova, E.G.

1980-01-01

A functional dependence between physicochemical properties of rare earth sesquioxides and energy state of rare earth atom sublattice valent electrons in sesquioxides is found out. The results of calculation of a simplified zone strucrure of rare earth sesquioxides are presented. The energy of the band of metal sublattice valent electrons for rare earth oxides is presented by the Chebyshev coefficients and polynomials and is calculated in the atomic units of mass. The density, melting points, standard change of enthalpy entropy, free energy, specific heat, standard entropy, forbidden zone width, static permitivity with a relative error of 10-12%, and thermal value of seeming activation energy, tangent of a dielectric losses angle, puncture voltage in rare earth oxides with a relative error of 20% are calculated on the base of calculation of electronic structure of rare earth sesquioxide in a condensed state and regression equations of calculation of oxide physicochemical properties. It is shown that only the Chebyshev coefficients determining the metal sublattice electronic structure in an oxide are ''information'' ones, i e. they contribute into the quantitative description of the system

Metallic Concentration in Karnaphuly Estuary Sediment Using Neutron Activation Analysis Technique

International Nuclear Information System (INIS)

Rahman, A.K.M.R.; Chakroborty, S.R.; Roy, P.K.; Dev, A.K.

2013-01-01

Thousands of tonnes of liquid waste, dirt and garbage from different mills and factories from Kaptai to Chittagong are dumped unhindered into the Karnaphuli River. Pollutants enter the river directly from urban sewerage and industrial waste discharges. Ships pollute waterways in many ways. All theses can contribute to the heavy and other metals of the water bodies. To find out concentration of different metallic elements and make a comparison with the world reference values twenty one surface sediment samples were collected from the different locations of Karnaphuly River near Chittagong city drainage outlet. Neutron Activation Analysis (NAA) technique was used for detecting the concentration qualitatively and quantitatively using the 3 MW TRIGA MARK II research reactor of Atomic Energy Research Establishment, Savar, Dhaka. Pearson correlation among the elements obtained using SPSS software. Three transitional metals Fe, Cr and Co, two alkali metals Rb and Na, two lanthanides La and Ce, and two metalloids As and Sb were determined. The concentrations of elements were compared with the world reference values. Some elements are found in elevated level. (author)

Cost-effectiveness of 13-valent pneumococcal conjugate vaccination in Mongolia.

Science.gov (United States)

Sundaram, Neisha; Chen, Cynthia; Yoong, Joanne; Luvsan, Munkh-Erdene; Fox, Kimberley; Sarankhuu, Amarzaya; La Vincente, Sophie; Jit, Mark

2017-02-15

The Ministry of Health (MOH), Mongolia, is considering introducing 13-valent pneumococcal conjugate vaccine (PCV13) in its national immunization programme to prevent the burden of disease caused by Streptococcus pneumoniae. This study evaluates the cost-effectiveness and budget impact of introducing PCV13 compared to no PCV vaccination in Mongolia. The incremental cost-effectiveness ratio (ICER) of introducing PCV13 compared to no PCV vaccination was assessed using an age-stratified static multiple cohort model. The risk of various clinical presentations of pneumococcal disease (meningitis, pneumonia, non-meningitis non-pneumonia invasive pneumococcal disease and acute otitis media) at all ages for thirty birth cohorts was assessed. The analysis considered both health system and societal perspectives. A 3+0 vaccine schedule and price of US$3.30 per dose was assumed for the baseline scenario based on Gavi, the Vaccine Alliance's advance market commitment tail price. The ICER of PCV13 introduction is estimated at US$52 per disability-adjusted life year (DALY) averted (health system perspective), and cost-saving (societal perspective). Although indirect effects of PCV have been well-documented, a conservative scenario that does not consider indirect effects estimated PCV13 introduction to cost US$79 per DALY averted (health system perspective), and US$19 per DALY averted (societal perspective). Vaccination with PCV13 is expected to cost around US$920,000 in 2016, and thereafter US$820,000 every year. The programme is likely to reduce direct disease-related costs to MOH by US$440,000 in the first year, increasing to US$510,000 by 2025. Introducing PCV13 as part of Mongolia's national programme appears to be highly cost-effective when compared to no vaccination and cost-saving from a societal perspective at vaccine purchase prices offered through Gavi. Notwithstanding uncertainties around some parameters, cost-effectiveness of PCV introduction for Mongolia remains

Development of сertified reference materials set for opened porosity of solid substances and materials (imitators

Directory of Open Access Journals (Sweden)

E. P. Sobina

2016-01-01

Full Text Available The article deals with data of research for development of certified reference materials set for opened porosity of solid substances and materials (imitators (OPTB SO UNIIM Set Certified Reference Materials GSO 10583-2015. The certified values of opened porosity of metal cylinders were established by the method of hydrostatic weighing before and after boring of holes in. The certified reference materials are intended for calibration and verification of measuring instruments of opened porosity, based on the Boyle - Mariotte's law.

Evaporated metal films as indicators of atmospheric pollution. II. Resistance measurements

Energy Technology Data Exchange (ETDEWEB)

Lodge, Jr, J P; Frank, E R

1962-01-01

There appears to be a direct relationship between gross atmospheric features associated with the accumulation of substances in air that are corrosive to metals and the rate of resistance change of thin metallic films. This behavior is the most striking in aluminum. The suggested apparatus provides an inexpensive and rapid method determining total atmospheric corrosiveness. 1 reference, 10 figures.

Fresh biological reference materials. Use in inter laboratory studies and as CRMs

International Nuclear Information System (INIS)

De Boer, J.

1999-01-01

Biological reference materials were prepared and packed in tins and glass jars to be used in inter laboratory studies on chlorobiphenyls and organochlorine pesticides, and trace metals, respectively. The materials were homogenised, sterilised and packed as wet tissue, which is unique for the purpose of inter laboratory studies and offers the advantage of studying the extraction and destruction steps of the analytical methods. In addition to their use in inter laboratory studies, some materials have been prepared or are being prepared as certified reference material for chlorobiphenyl analysis. (author)

The action of uranium hexafluoride on some metallic fluorides (1962); Action de l'hexafluorure d'uranium sur quelques fluorures metalliques (1962)

Energy Technology Data Exchange (ETDEWEB)

Michallet, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-12-15

A metallic difluoride is inert to UF{sub 6} unless the metal can exist in a higher valency state. In this case, UF{sub 6} acts as an oxidising agent and is transformed into UF{sub 4}. The fluorides of tri- and tetra-valent metals give rise to new compounds when they are maintained at a high temperature (500 deg. C) in the presence of uranium hexachloride vapour. The products obtained are characterized by their X-ray diffraction diagrams. The distributions of the lines of the powder diagrams are very similar to that of U{sub 4}F{sub 17}. Assuming that this resemblance is due to a stacking of identical fluorine atoms, it can be calculated that the corresponding structure is given by the theoretical formulae: MeF{sub 3}, 0,562 UF{sub 6}; MeF{sub 4}, 0,396 UF{sub 6} which are in good agreement with chemical measurements. (author) [French] Un di-fluorure metallique est inerte vis-a-vis de UF{sub 6}, sauf si le metal est susceptible d'exister a une valence plus elevee. Dans ce cas, UF{sub 6} joue le role d'un oxydant et se transforme en UF{sub 4}. Les fluorures de metaux tri et tetravalents donnent naissance a des composes nouveaux quand ils sont maintenus a haute temperature (500 deg. C) en presence de vapeur d'hexafluorure d'uranium. Les produits obtenus sont caracterises par leurs diagrammes de diffraction X. Les distributions de raies des diagrammes de poudre sont tres voisines de celles de U{sub 4}F{sub 17}. En supposant que cette analogie resulte d'un empilement d'ions fluor identique, le calcul conduit aux formules theoriques suivantes: MeF{sub 3}, 0,562 UF{sub 6}; MeF{sub 4}, 0,396 UF{sub 6} en bon accord avec les resultats des dosages chimiques. (auteur)

Heme-Containing Metal-Organic Frameworks for the Oxidative Degradation of Chemical Warfare Agents

Science.gov (United States)

2016-04-14

respectively; hydrogen atoms are omitted for clarity. ARO Final Progress Report...the hydrolysis of the ethoxy functional groups, the generation of the high-valent iron-oxo would provide an accessible route for the hydroxylation of...reaction mixture suggested the formation of ethoxy hydrolyzed product rather than the expected transformation of the methyl group. The hydrolysis of the

Quantification of Heavy Metals in Mining Affected Soil and Their Bioaccumulation in Native Plant Species.

Science.gov (United States)

Nawab, Javed; Khan, Sardar; Shah, Mohammad Tahir; Khan, Kifayatullah; Huang, Qing; Ali, Roshan

2015-01-01

Several anthropogenic and natural sources are considered as the primary sources of toxic metals in the environment. The current study investigates the level of heavy metals contamination in the flora associated with serpentine soil along the Mafic and Ultramafic rocks northern-Pakistan. Soil and wild native plant species were collected from chromites mining affected areas and analyzed for heavy metals (Cr, Ni, Fe, Mn, Co, Cu and Zn) using atomic absorption spectrometer (AAS-PEA-700). The heavy metal concentrations were significantly (p soil as compared to reference soil, however Cr and Ni exceeded maximum allowable limit (250 and 60 mg kg(-1), respectively) set by SEPA for soil. Inter-metal correlations between soil, roots and shoots showed that the sources of contamination of heavy metals were mainly associated with chromites mining. All the plant species accumulated significantly higher concentrations of heavy metals as compared to reference plant. The open dumping of mine wastes can create serious problems (food crops and drinking water contamination with heavy metals) for local community of the study area. The native wild plant species (Nepeta cataria, Impatiens bicolor royle, Tegetis minuta) growing on mining affected sites may be used for soil reclamation contaminated with heavy metals.

Organ- and species-specific accumulation of metals in two land snail species (Gastropoda, Pulmonata)

Energy Technology Data Exchange (ETDEWEB)

Boshoff, Magdalena, E-mail: magdalena.boshoff@ua.ac.be [University of Antwerp, Systemic Physiological and Ecotoxicological Research, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Jordaens, Kurt [Royal Museum for Central Africa (JEMU), Leuvensesteenweg 13, B-3080 Tervuren (Belgium); University of Antwerp, Evolutionary Ecology Group, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Backeljau, Thierry [University of Antwerp, Evolutionary Ecology Group, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Royal Belgian Institute of Natural Sciences (JEMU), Vautierstraat 29, B-1000 Brussels (Belgium); Lettens, Suzanna [Research Institute for Nature and Forest (INBO), Kliniekstraat 25, B-1070 Brussels (Belgium); Tack, Filip [Ghent University, Laboratory of Analytical Chemistry and Applied Ecochemistry, Coupure Links 265, B-9000 Ghent (Belgium); Vandecasteele, Bart [Institute for Agricultural and Fisheries Research (ILVO), Burg van Gansberghelaan 109, B-9820 Merelbeke (Belgium); De Jonge, Maarten; Bervoets, Lieven [University of Antwerp, Systemic Physiological and Ecotoxicological Research, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

2013-04-01

In order to evaluate the usefulness of terrestrial gastropods as bioindicators there is a need for studies that simultaneously compare (1) concentrations of metals in reference and polluted plots, (2) species within the same polluted habitat, (3) metal accumulation patterns in different organs and (4) metal accumulation patterns in relation to soil physicochemical properties. This study aims to assess metal accumulation patterns in two land snail species. Instead of analyzing an organism as a whole, investigating the partitioning of metals in different organs can provide information on the actual toxicological relevant fractions. Therefore, concentrations of Ag, Cd, Cr, Cu, Ni and Zn were examined in five different organs of Cepaea nemoralis, as well as in the foot and the body of Succinea putris. Snails were sampled at four polluted dredged sediment disposal localities and three adjacent less polluted reference plots situated along waterways in Flanders, Belgium. Due to the small size and problematic dissection of S. putris only the concentrations in the foot of both species could be compared. For this reason only, C. nemoralis can be described as a better bioindicator species that allows a far more detailed analysis of organ metal accumulation. This study showed that organs other than the digestive gland may be involved in the immobilization and detoxification of metals. Furthermore, pH, soil fractionation (clay %, silt %, sand %) and organic matter, correlate with metal accumulation in organs. However, most often the soil metal concentrations did not correlate with the concentrations found in snail organs. Metal concentrations in organs of both species (1) differed among polluted plots but rarely between polluted and reference plots within a locality, (2) were organ-specific (digestive gland > foot > albumen gland = spermoviduct = ovotestis), (3) were species-specific and (4) depended on the metal type (high Cd and Cu concentrations were observed in the

Investigation of the behaviour of zero-valent iron nanoparticles and their interactions with Cd2+ in wastewater by single particle ICP-MS.

Science.gov (United States)

Vidmar, Janja; Oprčkal, Primož; Milačič, Radmila; Mladenovič, Ana; Ščančar, Janez

2018-04-12

Zero-valent iron nanoparticles (nZVI) exhibit great potential for the removal of metal contaminants from wastewater. After their use, there is a risk that nZVI will remain dispersed in remediated water and represent potential nano-threats to the environment. Therefore, the behaviour of nZVI after remediation must be explored. To accomplish this, we optimised a novel method using single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) for the sizing and quantification of nZVI in wastewater matrices. H 2 reaction gas was used in MS/MS mode for the sensitive and interference-free determination of low concentrations of nZVI with a low size limit of detection (36nm). This method was applied to study the influence of different iron (Fe) loads (0.1, 0.25, 0.5 and 1.0gL -1 ) and water matrices (Milli-Q water, synthetic and effluent wastewater) on the behaviour of nZVI, their interactions with Cd 2+ and the efficiency of Cd 2+ removal. The aggregation and sedimentation of nZVI increased with settling time. Sedimentation was slower in effluent wastewater than in Milli-Q water or synthetic wastewater. Consequently, Cd 2+ was more efficiently (86%) removed from effluent wastewater than from synthetic wastewater (73%), while its removal from Milli-Q water was inefficient (19%). The trace amounts of Cd 2+ that remained in the remediated water were either dissolved or sorbed to residual nZVI. The results of the nanoremediation of effluent wastewater with varying Fe loads showed that sedimentation was faster at higher initial concentrations of nZVI. After seven days of settling, low concentrations of Fe remained in the effluent wastewater at Fe loads of 0.5gL -1 or higher, which could indicate that the use of nZVI in nanoremediation under the described conditions may not represent an environmental nano-threat. However, further studies are needed to assess the ecotoxicological impact of Fe-related NPs used for the nanoremediation of wastewaters. Copyright © 2018

A survey of reference electrodes for high temperature waters

International Nuclear Information System (INIS)

Molander, A.; Eriksson, Sture; Pein, K.

2000-11-01

, suggestions of variations of the conventional platinum electrode is given. Interesting variations are platinum electrodes with flowing electrolyte or quasi reversible hydrogen electrode. Development of silver chloride electrodes for extended lifetime can be done with e g a diffusion barrier to limit dilution. Also completely new types of reference electrodes are treated, as e g metal/metal oxide electrodes. These can be interesting but more development is required. Finally a survey of the measurements in BWR-PWR and CANDU reactors published in literature is given. In BWRs, American power plants (with electrodes from GE), Swedish power plants (with electrodes from Studsvik), Siemens and Toshiba have published measurements of larger extent. In PWRs, above all Ringhals and Siemens perform measurements today, even if a number of measurements through the years are published

The risk of cataract in relation to metal arc welding

DEFF Research Database (Denmark)

Slagor, Rebekka Michaelsen; Dornonville de la Cour, Morten; Bonde, Jens Peter

2016-01-01

.95–1.21] and the adjusted HR was 1.08 (95% CI 0.95–1.22). Age and diabetes were as expected strong risk factors. Conclusion: We found no increased risk of developing cataract among Danish metal welders who worked with arc welding from 1950–1985. This may be attributed to the effectiveness of personal safety equipment....... increases the risk of cataract. Method: We compared the risk of being diagnosed with cataract from 1987–2012 in a historic cohort of 4288 male metal arc welders against a reference group comprised of Danish skilled and unskilled male workers with similar age distribution. For the welders’ cohort...... adjusted for baseline data regarding age, diabetes, and social group. Results: There were 266 welders and 29 007 referents with a diagnosis and/or operation for cataract. The unadjusted HR for cataract comparing ever-welders with referents was 1.07 [95% confidence interval (95% CI) 0...

Effects of mining-derived metals on riffle-dwelling crayfish in southwestern Missouri and southeastern Kansas, USA

Science.gov (United States)

Allert, Ann L.; DiStefano, Robert J.; Schmitt, Christopher J.; Fairchild, James F.; Brumbaugh, William G.

2012-01-01

Riffle-dwelling crayfish populations were sampled at 16 sites in 4 tributaries of the Spring River located within the Tri-State Mining District in southwest Missouri. Crayfish density, physical habitat quality, and water quality were examined at each site to assess the ecological effects of mining-derived metals on crayfish. Metals (lead, zinc, and cadmium) were analyzed in samples of surface water, sediment, detritus, and whole crayfish. Sites were classified a posteriori into reference, mining, and downstream sites primarily based on metal concentrations in the materials analyzed. Three species of crayfish (Orconectes neglectus neglectus, O. macrus, and O. virilis) were collected during the study; however, only O. n. neglectus was collected at all sites. Mean crayfish densities were significantly lower at mining sites than at reference sites. Mean concentrations of metals were significantly correlated among the materials analyzed and were significantly greater at mining and downstream sites than at reference sites. Principal component analyses showed a separation of sites due to an inverse relationship among crayfish density, metals concentrations, and physical habitat quality variables. Sediment probable-effects quotients and surface-water toxic unit scores were significantly correlated; both indicated risk of toxicity to aquatic biota at several sites. Metals concentrations in whole crayfish at several sites exceeded concentrations known to be toxic to carnivorous wildlife. Mining-derived metals have the potential to impair ecosystem function through decreased organic matter processing and nutrient cycling in streams due to decreased crayfish densities.

Evidence for groundwater contamination by heavy metals through soil passage under acidifying conditions

NARCIS (Netherlands)

Wilkens, B.J.

1995-01-01

The research reported here is aimed at improving the knowledge of the mobility of the heavy metals cadmium and zinc in vulnerable soil types. We use the term vulnerable with reference to vulnerability of groundwater for contamination by soil leaching. At diffuse soil immissions of heavy metals,

Evaluation of 13-valent pneumococcal conjugate vaccine and concomitant meningococcal group C conjugate vaccine in healthy infants and toddlers in Spain.

Science.gov (United States)

Diez-Domingo, Javier; Gurtman, Alejandra; Bernaola, Enrique; Gimenez-Sanchez, Francisco; Martinon-Torres, Federico; Pineda-Solas, Valentin; Delgado, Alfonso; Infante-Marquez, Pilar; Liang, John Z; Giardina, Peter C; Gruber, William C; Emini, Emilio A; Scott, Daniel A

2013-11-04

Given the concurrent administration of multiple vaccines during routine pediatric immunizations, efforts to elucidate the potential interference of any vaccine on the immune response to the concomitantly administered antigens are fundamental to prelicensure clinical research. This phase 3 randomized controlled trial of 13-valent pneumococcal conjugate vaccine (PCV13) versus 7-valent PCV (PCV7) assessed immune responses of concomitantly administered meningococcal group C conjugated to diphtheria toxin cross-reactive material 197 (MnCCV-CRM197) in a 2-dose infant series and 15-month toddler dose. 619 subjects were randomized, 315 to PCV13 and 304 to PCV7. MnCCV-CRM197-induced immune responses were similar between the PCV13 and PCV7 groups, with >97% of the subjects achieving a ≥1:8 meningococcal serum bactericidal assay (SBA) titer after both dose 2 and the toddler dose. Geometric mean titers were lower in the PCV13 group 191.22 (167.72, 218.02) versus 266.19 (234.86, 301.71) following dose 2 and 432.28 (361.22, 517.31) versus 730.84 (642.05, 831.91) following the toddler dose. The geometric mean (GM) meningococcal SBA titer ratios (PCV13/PCV7) were 0.72 after dose 2 and 0.59 after the toddler dose. The criteria for MnCCV-CRM197 non-inferiority for GM titers were satisfied after dose 2. Percent responders was similar up to titers of 1:128. PCV13 elicited substantial antipneumococcal responses against all 13 serotypes, with ≥90% of the subjects achieving an antibody concentration ≥0.35μg/mL after dose 3 in the infant series. Safety and tolerability were similar between the vaccine groups. Immunogenicity results of MnCCV-CRM197 for PCV13 compared with PCV7 included lower GMTs, but the clinical significance of this is unknown as the proportion of infants achieving protective MenC antibody titers was comparable in the two groups. Percent responders were similar up to titers of 1:128. PCV13 has an acceptable safety profile in infants and toddlers, while providing

Direct Comparison of Immunogenicity Induced by 10- or 13-Valent Pneumococcal Conjugate Vaccine around the 11-Month Booster in Dutch Infants.

Directory of Open Access Journals (Sweden)

Alienke J Wijmenga-Monsuur

Full Text Available Since 2009/10, a 10- and a 13-valent pneumococcal conjugate vaccine (PCV are available, but only the 10-valent vaccine is now being used for the children in the Netherlands. As the vaccines differ in number of serotypes, antigen concentration, and carrier proteins this study was designed to directly compare quantity and quality of the antibody responses induced by PCV10 and PCV13 before and after the 11-month booster.Dutch infants (n = 132 were immunized with either PCV10 or PCV13 and DTaP-IPV-Hib-HepB at the age of 2, 3, 4 and 11 months. Blood samples were collected pre-booster and post-booster at one week and one month post-booster for quantitative and qualitative immunogenicity against 13 pneumococcal serotypes, as well as quantitative immunogenicity against diphtheria, tetanus, pertussis and Haemophilus influenzae type b. We compared immunogenicity induced by PCV13 and PCV10 for their ten shared serotypes.One month post-booster, pneumococcal serotype-specific IgG geometric mean concentrations (GMCs for the PCV13 group were higher compared with the PCV10 group for six serotypes, although avidity was lower. Serotype 19F showed the most distinct difference in IgG and, in contrast to other serotypes, its avidity was higher in the PCV13 group. One week post-booster, opsonophagocytosis for serotype 19F did not differ significantly between the PCV10- and the PCV13 group.Both PCV10 and PCV13 were immunogenic and induced a booster response. Compared to the PCV10 group, the PCV13 group showed higher levels for serotype 19F GMCs and avidity, pre- as well as post-booster, although opsonophagocytosis did not differ significantly between groups. In our study, avidity is not correlated to opsonophagocytotic activity (OPA and correlations between IgG and OPA differ per serotype. Therefore, besides assays to determine IgG GMCs, assays to detect opsonophagocytotic activity, i.e., the actual killing of the pneumococcus, are important for PCV evaluation. How

Preparation, characterization and use of a reference material to proficiency testing for determination of metals in fish tissue in natura

International Nuclear Information System (INIS)

Santana, Luciana Vieira de

2013-01-01

The proficiency tests are widely used to evaluate the analytical capacity of laboratories and also as part of the accreditation process. For this reason, are important tools for the control of the quality of the analytical results obtained in the laboratories that work directly with seafood companies. In Brazil there are no providers of proficiency testing for metals potentially toxic in fish tissues. In this work will be described all steps used for the production of reference materials to be used in a proficiency testing pilot study for As, Cd, Pb and Hg in fish tissue following the recommendations of the ISO Guide 35. He preparation scheme consisted in selecting the individuals, cleaning, grinding, homogenization and fortification with As, Cd and Pb in two concentration levels. The preparation resulted in 164 sachets of 10 g each. In order to evaluate the effect of gamma irradiation in the samples conservation 52 sachets were irradiated with 60 Co (10.00 ± 1.05 kGy) in a gamma cell. This material with others non irradiated 52 sachets were used for the homogeneity and stability studies. The remaining 60 were used for the proficiency testing. The results demonstrated that both materials were homogeneous and presented good stability (during a period of 45 days). However, the irradiated material present better integrity, concerning biological degradation, when stored in ambient temperature. For this reason they were used to the proficiency testing pilot program. Ten laboratories participated in the proficiency testing pilot study and the results were evaluated using the following tests: z-score, confidence ellipse and En numbers. This work demonstrates the capability of the laboratory to produce reference materials as well as to organize and conduct proficiency testing. (author)

Impact of 10-valent pneumococcal conjugate vaccine on pneumococcal meningitis in children up to two years of age in Brazil

Directory of Open Access Journals (Sweden)

Indianara Maria Grando

2015-02-01

Full Text Available The objective of this study was to analyze the impact of vaccination against Streptococcus pneumoniae on the morbidity and mortality from pneumococcal meningitis in children ≤ 2 years in Brazil, from 2007 to 2012. This is a descriptive study and ecological analysis using data from the Information System on Notifiable Diseases. Pre-vaccination (2007-2009 and post-vaccination (2011-2012 periods were defined to compare incidence rates and mortality. A total of 1,311 cases and 430 deaths were reported during the study period. Incidence decreased from 3.70/100,000 in 2007 to 1.84/100,000 in 2012, and mortality decreased from 1.30/100,000 to 0.40/100,000, or 50% and 69% respectively, with the greatest impact in the 6-11 month age group. This decrease in Pneumococcal meningitis morbidity and mortality rates two years after introduction of the 10-valent pneumococcal conjugate vaccine suggests its effectiveness.

Poisoning of domestic animals with heavy metals

Directory of Open Access Journals (Sweden)

Velev Romel

2009-01-01

Full Text Available The term heavy metal refers to a metal that has a relatively high density and is toxic for animal and human organism at low concentrations. Heavy metals are natural components of the Earth's crust. They cannot be degraded or destroyed. To a small extent they enter animal organism via food, drinking water and air. Some heavy metals (e.g cooper, iron, chromium, zinc are essential in very low concentrations for the survival of all forms of life. These are described as essential trace elements. However, when they are present in greater quantities, like the heavy metals lead, cadmium and mercury which are already toxic in very low concentrations, they can cause metabolic anomalies or poisoning. Heavy metal poisoning of domestic animals could result, for instance, from drinking-water contamination, high ambient air concentrations near emission sources, or intake via the food chain. Heavy metals are dangerous because they tend to bioaccumulate in a biological organism over time. Manifestation of toxicity of individual heavy metals varies considerably, depending on dose and time of exposure, species, gender and environmental and nutritional factors. Large differences exist between the effects of a single exposure to a high concentration, and chronic exposures to lower doses. The aim of this work is to present the source of poisoning and toxicity of some heavy metals (lead, mercury, cadmium, thallium, arsenic, as well as new data about effects of those heavy metals on the health of domestic animals. .

[Safety and immunogenicity of a 7-valent pneumococcal conjugate vaccine (Prevenar) booster dose in healthy Chinese toddlers].

Science.gov (United States)

Li, Rong-cheng; Li, Feng-xiang; Li, Yan-ping

2009-06-01

To evaluate the safety and immunogenicity of the booster dose of 7 valent pneumococcal conjugate vaccine (PCV7) to the healthy Chinese toddlers who had received 3 primary doses. Four hundred and eighty-eight Chinese toddlers received a booster dose of PCV7 at age of 12-15 months following a primary series of the vaccine given at ages 3, 4, 5 months separately with Diphtheria Tetanus Acellular Pertussis Combined Vaccine (DTaP) in Group 1 or concurrently with DTaP in Group 2. Following the booster dose immunization, each subject was followed up for 30 days to observe the safety of the vaccine. Blood samples were taken from a subset of subjects prior and post 30 days the booster dose immunization to evaluate immunogenicity. A high proportion of subjects in Group 1 (89%) and Group 2 (91%) remained afebrile after the booster dose. Local reactions to the PCV7 booster dose were generally mild. For each serotype, the rise in GMC (post-/pre-vaccination) showed a statistically significant difference (P<0.0001) between both groups. PCV7 administered as a booster dose is generally safe, well tolerate, and immunogenic in healthy Chinese toddlers.

On the system of provision of ojsc "MMC 'Norilsk Nickel'" with interstate and State certified reference materials for quality control of cobalt, nickel, copper and promproducts

Directory of Open Access Journals (Sweden)

T. V. Shabelnikova

2014-01-01

Full Text Available In order to manage the quality of OJSC "MMC "Norilsk Nickel" products the Centre of Certified Reference Material Development has developed and is currently successfully implementing a system of operations provision with interstate and state certified reference materials of nickel, cobalt and copper composition. The system wholly corresponds to modern metrological requirements. The Centre of Reference Materials Development, fulfilling leading function in the field of state certified reference material production and supply to the Company's operations, aims its activity both at the development of new types of certified reference materials in the form of metals and at widening the range of synthetic oxide certified reference materials. Developed for the first time, metallic state certified reference materials of nickel, cobalt composition with certified mass fractions of oxygen, hydrogen, nitrogen, sulfur and carbon were put into practice of the Company's analytical services work. Certified reference material use provides the possibility to take into account requirements of some consumers to the quality of nickel and produce by OJSC "MMC "Norilsk Nickel" and also helps to raise competitive ability of the products on the world metals market. Over recent years the Centre fulfilled the work on the development, certification in established order, approval and entering into the State Register twenty five types of state certified reference materials. Certified reference materials are intended for fulfillment of the analysis of chemical composition of nickel, cobalt and copper in terms of their conformity with both national and international standards.

Synthesis of Highly Reactive Subnano-sized Zero-valent Iron using Smectite Clay Templates

Science.gov (United States)

Gu, Cheng; Jia, Hanzhang; Li, Hui; Teppen, Brian J.; Boyd, Stephen A.

2010-01-01

A novel method was developed for synthesizing subnano-sized zero-valent iron (ZVI) using smectite clay layers as templates. Exchangeable Fe(III) cations compensating the structural negative charges of smectites were reduced with NaBH4, resulting in the formation of ZVI. The unique structure of smectite clay, in which isolated exchangeable Fe(III) cations reside near the sites of structural negative charges, inhibited the agglomeration of ZVI resulting in the formation of discrete regions of subnanoscale ZVI particles in the smectite interlayer regions. X-ray diffraction revealed an interlayer spacing of ~ 5 Å. The non-structural iron content of this clay yields a calculated ratio of two atoms of ZVI per three cation exchange sites, in full agreement with the XRD results since the diameter of elemental Fe is 2.5 Å. The clay-templated ZVI showed superior reactivity and efficiency compared to other previously reported forms of ZVI as indicated by the reduction of nitrobenzene; structural Fe within the aluminosilicate layers was nonreactive. At a 1:3 molar ratio of nitrobenzene:non-structural Fe, a reaction efficiency of 83% was achieved, and over 80% of the nitrobenzene was reduced within one minute. These results confirm that non-structural Fe from Fe(III)-smectite was reduced predominantly to ZVI which was responsible for the reduction of nitrobenzene to aniline. This new form of subnano-scale ZVI may find utility in the development of remediation technologies for persistent environmental contaminants, e.g. as components of constructed reactive domains such as reactive caps for contaminated sediments. PMID:20446730

Synthesis of highly reactive subnano-sized zero-valent iron using smectite clay templates.

Science.gov (United States)

Gu, Cheng; Jia, Hanzhong; Li, Hui; Teppen, Brian J; Boyd, Stephen A

2010-06-01

A novel method was developed for synthesizing subnano-sized zero-valent iron (ZVI) using smectite clay layers as templates. Exchangeable Fe(III) cations compensating the structural negative charges of smectites were reduced with NaBH(4), resulting in the formation of ZVI. The unique structure of smectite clay, in which isolated exchangeable Fe(III) cations reside near the sites of structural negative charges, inhibited the agglomeration of ZVI resulting in the formation of subnanoscale ZVI particles in the smectite interlayer regions. X-ray diffraction revealed an interlayer spacing of approximately 5 A. The non-structural iron content of this clay yields a calculated ratio of two atoms of ZVI per three cation exchange sites, in full agreement with the X-ray diffraction (XRD) results since the diameter of elemental Fe is 2.5 A. The clay-templated ZVI showed superior reactivity and efficiency compared to other previously reported forms of ZVI as indicated by the reduction of nitrobenzene; structural Fe within the aluminosilicate layers was nonreactive. At a 1:3 molar ratio of nitrobenzene/non-structural Fe, a reaction efficiency of 83% was achieved, and over 80% of the nitrobenzene was reduced within one minute. These results confirm that non-structural Fe from Fe(III)-smectite was reduced predominantly to ZVI which was responsible for the reduction of nitrobenzene to aniline. This new form of subnanoscale ZVI may find utility in the development of remediation technologies for persistent environmental contaminants, for example, as components of constructed reactive domains such as reactive caps for contaminated sediments.

Enhancing the efficiency of zero valent iron by electrolysis: Performance and reaction mechanism.

Science.gov (United States)

Xiong, Zhaokun; Lai, Bo; Yang, Ping

2018-03-01

Electrolysis was applied to enhance the efficiency of micron-size zero valent iron (mFe 0 ) and thereby promote p-nitrophenol (PNP) removal. The rate of PNP removal by mFe 0 with electrolysis was determined in cylindrical electrolysis reactor that employed annular aluminum plate cathode as a function of experimental factors, including initial pH, mFe 0 dosage and current density. The rate constants of PNP removal by Ele-mFe 0 were 1.72-144.50-fold greater than those by pristine mFe 0 under various tested conditions. The electrolysis-induced improvement could be primarily ascribed to stimulated mFe 0 corrosion, as evidenced by Fe 2+ release. The application of electrolysis could extend the working pH range of mFe 0 from 3.0 to 6.0 to 3.0-10.0 for PNP removal. Additionally, intermediates analysis and scavengers experiments unraveled the reduction capacity of mFe 0 was accelerated in the presence of electrolysis instead of oxidation. Moreover, the electrolysis effect could also delay passivation of mFe 0 under acidic condition, as evidenced by SEM-EDS, XRD, and XPS analysis after long-term operation. This is mainly due to increased electromigration meaning that iron corrosion products (iron hydroxides and oxides) are not primarily formed in the vicinity of the mFe 0 or at its surface. In the presence of electrolysis, the effect of electric field significantly promoted the efficiency of electromigration, thereby enhanced mFe 0 corrosion and eventually accelerated the PNP removal rates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gold nanoparticles modified with coordination compounds of metals: synthesis and application

International Nuclear Information System (INIS)

Beloglazkina, Elena K; Majouga, Alexander G; Romashkina, Renata B; Zyk, Nikolai V; Zefirov, Nikolai S

2012-01-01

The data on the preparation methods and applications of gold nanoparticles with coordinated metal ions on the surfaces are generalized. The currently available data on the interaction of metal ions with gold nanoparticles modified with organic (particularly, sulfur-containing) ligands comprising terminal chelating groups are considered in detail as well as the applications of such modified nanoparticles. The bibliography includes 141 references.

Ochrobactrum anthropi used to control ammonium for nitrate removal by starch-stabilized nanoscale zero valent iron.

Science.gov (United States)

Zhou, Jun; Sun, Qianyu; Chen, Dan; Wang, Hongyu; Yang, Kai

2017-10-01

In this study, the hydrogenotrophic denitrifying bacterium Ochrobactrum anthropi was added in to the process of nitrate removal by starch-stabilized nanoscale zero valent iron (nZVI) to minimize undesirable ammonium. The ammonium control performance and cooperative mechanism of this combined process were investigated, and batch experiments were conducted to discuss the effects of starch-stabilized nZVI dose, biomass, and pH on nitrate reduction and ammonium control of this system. The combined system achieved satisfactory performance because the anaerobic iron corrosion process generates H 2 , which is used as an electron donor for the autohydrogenotrophic bacterium Ochrobactrum anthropi to achieve the autohydrogenotrophic denitrification process converting nitrate to N 2 . When starch-stabilized nZVI dose was increased from 0.5 to 2.0 g/L, nitrate reduction rate gradually increased, and ammonium yield also increased from 9.40 to 60.51 mg/L. Nitrate removal rate gradually decreased and ammonium yield decreased from 14.93 to 2.61 mg/L with initial OD 600 increasing from 0.015 to 0.080. The abiotic Fe 0 reduction process played a key role in nitrate removal in an acidic environment and generated large amounts of ammonium. Meanwhile, the nitrate removal rate decreased and ammonium yield also reduced in an alkaline environment.

Facile 3D Metal Electrode Fabrication for Energy Applications via Inkjet Printing and Shape Memory Polymer

International Nuclear Information System (INIS)

Roberts, R C; Wu, J; Li, D C; Hau, N Y; Chang, Y H; Feng, S P

2014-01-01

This paper reports on a simple 3D metal electrode fabrication technique via inkjet printing onto a thermally contracting shape memory polymer (SMP) substrate. Inkjet printing allows for the direct patterning of structures from metal nanoparticle bearing liquid inks. After deposition, these inks require thermal curing steps to render a stable conductive film. By printing onto a SMP substrate, the metal nanoparticle ink can be cured and substrate shrunk simultaneously to create 3D metal microstructures, forming a large surface area topology well suited for energy applications. Polystyrene SMP shrinkage was characterized in a laboratory oven from 150-240°C, resulting in a size reduction of 1.97-2.58. Silver nanoparticle ink was patterned into electrodes, shrunk, and the topology characterized using scanning electron microscopy. Zinc-Silver Oxide microbatteries were fabricated to demonstrate the 3D electrodes compared to planar references. Characterization was performed using 10M potassium hydroxide electrolyte solution doped with zinc oxide (57g/L). After a 300s oxidation at 3Vdc, the 3D electrode battery demonstrated a 125% increased capacity over the reference cell. Reference cells degraded with longer oxidations, but the 3D electrodes were fully oxidized for 4 hours, and exhibited a capacity of 5.5mA-hr/cm 2 with stable metal performance

Multivariate analysis of selected metals in tannery effluents and related soil.

Science.gov (United States)

Tariq, Saadia R; Shah, Munir H; Shaheen, N; Khalique, A; Manzoor, S; Jaffar, M

2005-06-30

Effluent and relevant soil samples from 38 tanning units housed in Kasur, Pakistan, were obtained for metal analysis by flame atomic absorption spectrophotometric method. The levels of 12 metals, Na, Ca, K, Mg, Fe, Mn, Cr, Co, Cd, Ni, Pb and Zn were determined in the two media. The data were evaluated towards metal distribution and metal-to-metal correlations. The study evidenced enhanced levels of Cr (391, 16.7 mg/L) and Na (25,519, 9369 mg/L) in tannery effluents and relevant soil samples, respectively. The effluent versus soil trace metal content relationship confirmed that the effluent Cr was strongly correlated with soil Cr. For metal source identification the techniques of principal component analysis, and cluster analysis were applied. The principal component analysis yielded two factors for effluents: factor 1 (49.6% variance) showed significant loading for Ca, Fe, Mn, Cr, Cd, Ni, Pb and Zn, referring to a tanning related source for these metals, and factor 2 (12.6% variance) with higher loadings of Na, K, Mg and Co, was associated with the processes during the skin/hide treatment. Similarly, two factors with a cumulative variance of 34.8% were obtained for soil samples: factor 1 manifested the contribution from Mg, Mn, Co, Cd, Ni and Pb, which though soil-based is basically effluent-derived, while factor 2 was found associated with Na, K, Ca, Cr and Zn which referred to a tannery-based source. The dendograms obtained from cluster analysis, also support the observed results. The study exhibits a gross pollution of soils with Cr at levels far exceeding the stipulated safe limit laid down for tannery effluents.

Improving crop tolerance to heavy metal stress by polyamine application.

Science.gov (United States)

Soudek, Petr; Ursu, Marina; Petrová, Šárka; Vaněk, Tomáš

2016-12-15

Many areas have been heavily contaminated by heavy metals from industry and are not suitable for food production. The consumption of contaminated foods represents a health risk in humans, although some heavy metals are essential at low concentrations. Increasing the concentrations of essential elements in foods is one goal to improve nutrition. The aim of this study was to increase the accumulation of heavy metals in plant foods by the external application of putrescine. The levels of cadmium, zinc and iron were measured in different vegetables grown in hydroponic medium supplemented with heavy metals and compared with those grown in a reference medium. The estimated daily intake, based on the average daily consumption for various vegetable types, and the influence of polyamines on metal uptake were calculated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanism insights into enhanced trichloroethylene removal using xanthan gum-modified microscale zero-valent iron particles.

Science.gov (United States)

Xin, Jia; Han, Jun; Zheng, Xilai; Shao, Haibing; Kolditz, Olaf

2015-03-01

This report focuses on the enhancement in trichloroethylene (TCE) removal from contaminated groundwater using xanthan gum (XG)-modified, microscale, zero-valent iron (mZVI). Compared with bare mZVI, XG-coated mZVI increased the TCE removal efficiency by 30.37% over a 480-h experimental period. Because the TCE removal is attributed to both sorption and reduction processes, the contributions from sorption and reduction were separately investigated to determine the mechanism of XG on TCE removal using mZVI. The results showed that the TCE sorption capacity of mZVI was lower in the presence of XG, whereas the TCE reduction capacity was significantly increased. The FTIR spectra confirmed that XG, which is rich in hydrophilic functional groups, was adsorbed onto the iron surface through intermolecular hydrogen bonds, which competitively repelled the sorption and mass transfer of TCE toward reactive sites. The variations in the pH, Eh, and Fe(2+) concentration as functions of the reaction time were recorded and indicated that XG buffered the solution pH, inhibited surface passivation, and promoted TCE reduction by mZVI. Overall, the XG-modified mZVI was considered to be potentially effective for the in-situ remediation of TCE contaminated groundwater due to its high stability and dechlorination reactivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

PHARMACOECONOMIC ASSESSMENT OF 13-VALENT PNEUMOCOCCAL CONJUGATE VACCINE IN IMMUNIZATION OF CHILDREN IN RUSSIAN FEDERATION

Directory of Open Access Journals (Sweden)

​A. V. Rudakova

2014-01-01

Full Text Available Aim: cost-effectiveness assessment and budget impact analysis for 13-valent pneumococcal conjugate vaccine (PCV13 in infant immunization program in Russian Federation. Materials and methods: 10 year modeling with social perspective (direct medical and indirect costs and life expectancy with discounting by 3,5% per year and population effect based on results of clinical studies, global PCV13 use and Russian epidemiological data has been established. Budget impact has been analyzed without discounting. Direct effect was assessed by influence on pneumococcal meningitis, bacteremia, pneumonia and acute otitis media (AOM incidence, population effect — by pneumococcal meningitis and hospitalized all-cause pneumonia incidence. Results: Possible PCV13 effectiveness was estimated as 76,6% for invasive pneumococcal diseases (IPD and 23,7% for hospitalized cases of AOM. Vaccination (per 100 000 vaccinated infants can prevent 13,8 lethal cases in vaccinated population and 171,1 — in unvaccinated population. Cost-effectiveness ratio for PCV13 is estimated as 32,400 rubles / LYG and 32,400 rubles / QALY. Cost of 1 lethal case prevention is 140 100 rubles, additional cost for 10 years is 111,5 rubles per child. Conclusions: PCV13 mass vaccination of infants in Russian Federation is highly cost-effective and will significantly cut expenses due to pneumococcal diseases treatment. 

Brassica napus has a key role in the recovery of the health of soils contaminated with metals and diesel by rhizoremediation.

Science.gov (United States)

Lacalle, Rafael G; Gómez-Sagasti, María T; Artetxe, Unai; Garbisu, Carlos; Becerril, José M

2018-03-15

Contaminated soils are frequently characterized by the simultaneous presence of organic and inorganic contaminants, as well as a poor biological and nutritional status. Rhizoremediation, the combined use of phytoremediation and bioremediation, has been proposed as a Gentle Remediation Option to rehabilitate multi-contaminated soils. Recently, newer techniques, such as the application of metallic nanoparticles, are being deployed in an attempt to improve traditional remediation options. In order to implement a phytomanagement strategy on calcareous alkaline peri-urban soils simultaneously contaminated with several metals and diesel, we evaluated the effectiveness of Brassica napus L., a profitable crop species, assisted with organic amendment and zero-valent iron nanoparticles (nZVI). A two-month phytotron experiment was carried out using two soils, i.e. amended and unamended with organic matter. Soils were artificially contaminated with Zn, Cu and Cd (1500, 500 and 50mgkg -1 , respectively) and diesel (6000mgkg -1 ). After one month of stabilization, soils were treated with nZVI and/or planted with B. napus. The experiment was conducted with 16 treatments resulting from the combination of the following factors: amended/unamended, contaminated/non-contaminated, planted/unplanted and nZVI/no-nZVI. Soil physicochemical characteristics and biological indicators (plant performance and soil microbial properties) were determined at several time points along the experiment. Carbonate content of soils was the crucial factor for metal immobilization and, concomitantly, reduction of metal toxicity. Organic amendment was essential to promote diesel degradation and to improve the health and biomass of B. napus. Soil microorganisms degraded preferably diesel hydrocarbons of biological origin (biodiesel). Plants had a remarkable positive impact on the activity and functional diversity of soil microbial communities. The nZVI were ineffective as soil remediation tools, but did not

Accumulation of metals in vegetation established in ash constructions; Ackumulering av metaller i vegetation paa geotekniska askkonstruktioner

Energy Technology Data Exchange (ETDEWEB)

Hemstroem, Kristian; Wik, Ola (SGI, Statens geotekniska institut (Sweden)); Bramryd, Torleif; Johansson, Michael (Lunds Universitet, Miljoestrategi (Sweden)); Jaegerbrand, Annika (VTI, Statens Vaeg och transportforskningsinstitut (Sweden))

2012-02-15

The overall aim of this study was to investigate how the use of ash in a long-term perspective affects the surrounding flora and fauna with regard to the accumulation of metals in the ecosystem through plant uptake and exposure to grazing animals. The study included a field study and a cultivation experiment. In the field study, the accumulation of metals and metalloids in leaves of trees and shrubs that had self established and grown in lysimeters with aged MSWI bottom ash and aged biofuel ash was determined. In the cultivation experiment, the accumulation of metals and metalloids from the studied materials in ryegrass was determined. Reference materials in the cultivation experiment were two conventional geotechnical materials, crushed rock and excavated soil. Leaves from trees and bushes in the vicinity of the ash lysimeters were used as reference materials in the field study. Contamination of plant samples with particles, through splashing during rain, dusting, or in connection with sampling, proved to have had a major impact on the measured metal and metalloid concentrations in several grass samples in the cultivation experiment. The results also indicate that contamination of plant samples with particles occurred in the field study. In this case, probably due to atmospheric deposition. The particle contamination complicated the evaluation of some of the results in the project since the intention was to study accumulation by roots from the studied ash materials, but, on the other hand, the particle contamination showed the importance of taking into account the spreading of contaminants through particles as an exposure route for grazing animals. In the field study, only Cd and Zn in aspen, willow and birch exhibited elevated levels in the leaves due to root uptake from MSWI bottom ash compared to the reference samples. In addition, elevated levels of As was observed in leaves from trees in the biofuel ash. The total content of As was similar in all studied

Positron prevacancy effects in pure annealed metals

International Nuclear Information System (INIS)

Smedskjaer, L.C.

1981-06-01

The low-temperature prevacancy effects sometimes observed with positrons in well-annealed high-purity metals are discussed. It is shown that these effects are not experimental artifacts, but are due to trapping of the positrons. It is suggested that dislocations are responsible for these trapping effects. 46 references, 5 figures

LA VACUNACIÓN ANTI-NEUMOCÓCICA CON LA VACUNA CONJUGADA 13-VALENTE EN POBLACIÓN INMUNOCOMPETENTE DE 65 AÑOS: ANALISIS DEL IMPACTO PRESUPUESTARIO EN ESPAÑA APLICANDO UN MODELO DE TRANSMISIÓN DINÁMICA

Directory of Open Access Journals (Sweden)

Reyes Lorente Antoñanzas

2016-01-01

Full Text Available Fundamentos: Las infecciones causadas por el Streptococcus pneumoniae en el adulto tienen repercusiones importantes en la salud. El objetivo fue analizar el impacto económico y sanitario en 5 años de la vacunación de la cohorte española de 65 años inmunocompetente con la vacuna antineumocócica conjugada 13-valente.Métodos: Mediante un modelo de transmisión dinámica basado en ecuaciones diferenciales se analizó la carga de la enfermedad neumocócica (EN en sujetos de 65 años en 5 años, siendo vacunada anualmente el 36,5% de la cohorte. Se aplicó la eficacia de la vacuna del 52,5% observada en el estudio CAPITA en pacientes de 65 años inmunocompetentes, cobertura de serotipos vacunales del 63,4% (estudio CAPA, incidencia de infección neumocócica de 162,2/100.000 casos año (CMBD 2010-2013 y proporción de vacunados previamente al arranque del modelo del 0,99%. La perspectiva fue la del Sistema Nacional de Salud (SNS. Costes de casos de EN según CMBD y precio de venta de laboratorio de la vacuna conjugada.Resultados: En 5 años la vacunación con vacuna conjugada 13-valente espera evitar 10.360 casos de EN (7.411 hospitalizaciones por neumonías y 699 muertes (14.736 años de vida ganados -AVG-, en una cohorte de 65 a 69 años de edad. El coste de vacunación esperado de 36,5 millones de euros se compensaría completamente por la reducción de 41,5 millones de costes médicos evitados, con un ahorro neto acumulado de 3,8 millones de euros a precios constantes (4,9 a precios corrientes.Conclusión: La vacunación con vacuna conjugada 13-valente en adultos de 65 años inmunocompetentes resulta eficiente para el Sistema Nacional de Salud, reduciendo la carga de enfermedad y evitando un número importante de muertes.

Approaches for enhanced phytoextraction of heavy metals.

Science.gov (United States)

Bhargava, Atul; Carmona, Francisco F; Bhargava, Meenakshi; Srivastava, Shilpi

2012-08-30

The contamination of the environment with toxic metals has become a worldwide problem. Metal toxicity affects crop yields, soil biomass and fertility. Soils polluted with heavy metals pose a serious health hazard to humans as well as plants and animals, and often requires soil remediation practices. Phytoextraction refers to the uptake of contaminants from soil or water by plant roots and their translocation to any harvestable plant part. Phytoextraction has the potential to remove contaminants and promote long-term cleanup of soil or wastewater. The success of phytoextraction as a potential environmental cleanup technology depends on factors like metal availability for uptake, as well as plants ability to absorb and accumulate metals in aerial parts. Efforts are ongoing to understand the genetics and biochemistry of metal uptake, transport and storage in hyperaccumulator plants so as to be able to develop transgenic plants with improved phytoremediation capability. Many plant species are being investigated to determine their usefulness for phytoextraction, especially high biomass crops. The present review aims to give an updated version of information available with respect to metal tolerance and accumulation mechanisms in plants, as well as on the environmental and genetic factors affecting heavy metal uptake. The genetic tools of classical breeding and genetic engineering have opened the door to creation of 'remediation' cultivars. An overview is presented on the possible strategies for developing novel genotypes with increased metal accumulation and tolerance to toxicity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Application of monocarboxylic acids for the extraction of metal ions-literature survey

International Nuclear Information System (INIS)

Brzozka, Z.; Rozycki, C.

1980-01-01

In the paper there is presented a literature review concerning the application of monocarboxylic acids for extraction of metal ions. The following problems are discussed: characteristic of monocarboxylic acids and their mixtures, the equilibria between the acid solution in organic solvent and aqueous phase, the mechanism of acid partition, complexes of carboxylic acids and metal ions in aqueous phase, mechanism of extraction by means of carboxylic acids as well as the problems concerning the extraction of individual metal ions. Data about the extraction of metal ions are presented in table. The 138 references are given. (author)

Study of heavy metal pollution in mangrove sediments reference to marine environment along the coastal areas of Pakistan

International Nuclear Information System (INIS)

Khattak, M.I.; Khattak, M.I.

2011-01-01

The aim of this paper is to measure the concentration of heavy metals (Cd, Co, Pb, Cr, Zn, Cu and Fe) in Mangrove sediments. The concentrations of heavy metals (Cd, Co, Pb, Cr, Zn, Cu and Fe) were measured in different samples of in different Mangroves sediments along the coastal areas of Pakistan and was found that concentration of heavy metals in the Mangrove sediments near to Lyari and Malir river discharge points are at much higher level than the Mangrove sediments of Port Qasim area which are not according to WHO standard and are very are very serious health hazardous. In addition to point sources, possible reasons of non point sources were also discussed. (author)

Using graphitic foam as the bonding material in metal fuel pins for sodium fast reactors

International Nuclear Information System (INIS)

Karahan, Aydın; Kazimi, Mujid S.

2013-01-01

The study evaluates the possible use of graphite foam as the bonding material between U–Pu–Zr metallic fuel and steel clad for sodium fast reactor applications using FEAST-METAL fuel performance code. Furthermore, the applicability of FEAST-METAL to the advanced fuel designs is demonstrated. Replacing the sodium bond with a chemically stable foam material would eliminate fuel clad metallurgical interactions, and allow for fuel swelling under low external stress. Hence, a significant improvement is expected for the steady state and transient performance. FEAST-METAL was used to assess the thermo-mechanical behavior of the new fuel form and a reference metallic fuel pin. Nearly unity conversion ratio, 75% smear density U–15Pu–6Zr metallic fuel pin with sodium bond, and T91 cladding was selected as a reference case. It was found that operating the reference case at high clad temperatures (600–660 °C) results in (1) excessive clad wastage formation/clad thinning due to lanthanide migration and formation of brittle phases at clad inner surface, and (2) excessive clad hoop strain at the upper axial section due mainly to the occurrence of thermal creep. The combination of these two factors may lead to cladding breach. The work concludes that replacing the sodium bond with 80% porous graphite foam and reducing the fuel smear density to 70%, it is likely that the fuel clad metallurgical interaction would be eliminated while the fuel swelling is allowed without excessive fuel clad mechanical interaction. The suggested design appears as an alternative for a high performance metallic fuel design for sodium fast reactors

Using graphitic foam as the bonding material in metal fuel pins for sodium fast reactors

Energy Technology Data Exchange (ETDEWEB)

Karahan, Aydın, E-mail: karahan@alum.mit.edu; Kazimi, Mujid S.

2013-10-15

The study evaluates the possible use of graphite foam as the bonding material between U–Pu–Zr metallic fuel and steel clad for sodium fast reactor applications using FEAST-METAL fuel performance code. Furthermore, the applicability of FEAST-METAL to the advanced fuel designs is demonstrated. Replacing the sodium bond with a chemically stable foam material would eliminate fuel clad metallurgical interactions, and allow for fuel swelling under low external stress. Hence, a significant improvement is expected for the steady state and transient performance. FEAST-METAL was used to assess the thermo-mechanical behavior of the new fuel form and a reference metallic fuel pin. Nearly unity conversion ratio, 75% smear density U–15Pu–6Zr metallic fuel pin with sodium bond, and T91 cladding was selected as a reference case. It was found that operating the reference case at high clad temperatures (600–660 °C) results in (1) excessive clad wastage formation/clad thinning due to lanthanide migration and formation of brittle phases at clad inner surface, and (2) excessive clad hoop strain at the upper axial section due mainly to the occurrence of thermal creep. The combination of these two factors may lead to cladding breach. The work concludes that replacing the sodium bond with 80% porous graphite foam and reducing the fuel smear density to 70%, it is likely that the fuel clad metallurgical interaction would be eliminated while the fuel swelling is allowed without excessive fuel clad mechanical interaction. The suggested design appears as an alternative for a high performance metallic fuel design for sodium fast reactors.

Production of oxide-metal P/M composites using pulsed plasma heating

Energy Technology Data Exchange (ETDEWEB)

Blinkov, I.V.; Manukhin, A.V.; Ostapovich, A.O.; Pavlov, IU.A.

1987-08-01

The possibility of producing oxide-metal P/M composites using plasma generated by a pulsed discharge is investigated experimentally for the system Al/sup 2/O/sub 3/-Ni. It is found that Al/sup 2/O/sub 3/ metallization in plasma is accompanied by spheroidization; changes in the physicomechanical properties of the Al/sup 2/O/sub 3/-Ni composite during plasma treatment are examined. The characteristic features of the process associated with the effect of pulsed energy on the disperse flow of the oxide-metal mixture are discussed. 7 references.

Heavy metal pollution of agricultural soils

Energy Technology Data Exchange (ETDEWEB)

Jarvis, S.C.

1975-01-01

Inputs of heavy metals to soils have increased recently and there is much concern that they may be toxic at various stages along the food chain and ultimately to man. Cobalt, copper, iron, manganese, molybdenum, zinc, chromium, nickel, cadmium and lead move from geochemical sources to plants and then to animals and man; they then are returned in various forms to soil to complete the cycle. The ways in which heavy metals may be added to soils are reviewed. They include: aerial inputs by air pollution, fertilizers, pesticides, farm slurries and sewage sludge. Possibly the source of contamination which is to have the most impact on soils used for the production of crops is sewage sludge. The fate of heavy metal added to soils is discussed in relation to form, mobility, uptake by plants, effect of soil conditions on availability to plants, and toxicity to animals. 56 references.

Biological opportunities for metal recovery

International Nuclear Information System (INIS)

Holmes, D.S.; Debus, S.H.

1991-01-01

An overview is presented of existing biological technologies for the recovery of copper and uranium. Engineering and biological challenges and opportunities in these areas are discussed. New opportunities for the bio oxidation of refractory goal ore are described. Techniques for the development of new strains of microorganisms for commercial metal recovery applications are discussed with special reference to the use of genetic manipulation for bacterial strain improvement. (author)

A review on heavy metal contamination in the soil worldwide: Situation, impact and remediation techniques

OpenAIRE

Chao Su; LiQin Jiang; WenJun Zhang

2014-01-01

Heavy metals in the soil refers to some significant heavy metals of biological toxicity, including mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), and arsenic (As), etc. With the development of the global economy, both type and content of heavy metals in the soil caused by human activities have gradually increased in recent years, which have resulted in serious environment deterioration. In present study we compared and analyzed soil contamination of heavy metals in various cities/count...

Metal accumulation in wild-caught opossum.

Science.gov (United States)

Lockhart, J Mitchell; Siddiqui, Samreen; Loughry, W J; Bielmyer-Fraser, Gretchen K

2016-06-01

The Virginia opossum (Didelphis virginiana) is widespread in the USA, ranging south through Latin America. The ecology of opossums is such that they are in frequent contact with soils, suggesting that they may function as a valuable bioindicator for chemical contamination in terrestrial environments. Surprisingly, there have been virtually no toxicology studies on opossums. Here, we provide the first analysis of metal contaminants in opossum liver tissues. Liver samples were obtained from 471 opossums, collected from 2003 to 2006, at four sites in North Florida and South Georgia, USA, and concentrations of copper, lead, nickel, selenium, and zinc were measured. We found little evidence of age differences in the concentration of any of the metals. However, there were at least some significant differences between years, males and females, and between sites for each metal, although the pattern of these differences was not always consistent across metals. Concentrations of metals in liver tissue were positively correlated with one another, primarily of each metal (except Pb) with zinc. Reference levels of metal contaminants are not available for opossums, but concentrations of Cu, Ni, Pb, and Zn in our samples were for the most part significantly higher than those reported from liver tissues of nine-banded armadillos (Dasypus novemcinctus) collected at the same sites and in the same years. Data from other small mammals studied elsewhere further indicate that metal concentrations in opossums were high, but at this time, it is not possible to determine if these elevated levels generated toxicity. The substantial temporal and spatial variation we found in metal concentrations suggests that determination of baseline levels for opossums may not be straightforward. Nonetheless, this is the first study quantifying metal accumulation in the livers of Didelphis virginiana and, as such, provides an important starting point for future research.

Review of thermodinamic and mechanical properties of hydrogen-transition metal systems

International Nuclear Information System (INIS)

Mathias, H.; Katz, Y.

1978-04-01

A large body of fundamental and empirical knowledge has been acquired during many years of research concerning the interactions between hydrogen and metals, the location of hydrogen in metal structures, its mobility in metals and its influence on mechanical properties of metals. Much progress has been made in the understanding of related phenomena, and various theories have been proposed, but considerable disagreement still exist about basic mechanisms involved. The growing interest in these subjects and their important role in science and technology are well documented by many reviews and symposia. A general survey of these topics with reference to experimental results and theories related to thermodynamic and mechanical properties of hydrogen-transition metal systems, such as H-Pd, H-Ti, H-Fe etc. is given in the present review. Special emphasis is given to hydrogen embrittlement of metals

Metal accumulation and oxidative stress responses in Ulva spp. in the presence of nocturnal pulses of metals from sediment: A field transplantation experiment under eutrophic conditions

KAUST Repository

Pereira, Patrícia M R

2014-03-01

In aquatic systems under eutrophic conditions, remobilization of metals from sediment to the overlying water may occur. Consequently, adaptive responses of local organisms could result from the accumulation of metals intermittently released from the sediment. In summer 2007, a field transplantation experiment was performed in the Óbidos lagoon (Portugal) with Ulva spp. comprising three short-term exposures (between 15:30-23:30; 23:30-07:30; 07:30-15:30) during a 24-h period. In each period, Ulva spp. was collected at a reference site located in the lower lagoon (LL) and transplanted to a eutrophic site located at the Barrosa branch (BB), characterized by moderate metal contamination. For comparison purposes, macroalgae samples were simultaneously exposed at LL under the same conditions. Both sites were surveyed in short-time scales (2-4 h) for the analysis of the variability of physical-chemical parameters in the water and metal levels in suspended particulate matter. The ratios to Al of particulate Mn, Fe, Cu and Pb increased during the period of lower water oxygenation at the eutrophic site, reaching 751 × 10-4, 0.67, 12 × 10-4, 9.9 × 10-4, respectively, confirming the release of metals from the sediment to water during the night. At the reference site, dissolved oxygen oscillated around 100%, Mn/Al ratios were considerably lower (81 × 10-4-301 × 10-4) compared to BB (234 × 10-4-790 × 10-4), and no increases of metal/Al ratios were found during the night. In general, algae uptake of Mn, Cu, Fe, Pb and Cd was significantly higher at the eutrophic site compared to the reference site. The results confirmed the potential of Ulva spp. as bioindicator of metal contamination and its capability to respond within short periods. An induction of SOD, an inhibition of CAT and the increase of LPO were recorded in Ulva spp. exposed at BB (between 23:30 and 7:30) probably as a response to the higher incorporation of Mn, Fe and Pb in combination with the lack of

A review on heavy metal contamination in the soil worldwide: Situation, impact and remediation techniques

Directory of Open Access Journals (Sweden)

Chao Su

2014-06-01

Full Text Available Heavy metals in the soil refers to some significant heavy metals of biological toxicity, including mercury (Hg, cadmium (Cd, lead (Pb, chromium (Cr, and arsenic (As, etc. With the development of the global economy, both type and content of heavy metals in the soil caused by human activities have gradually increased in recent years, which have resulted in serious environment deterioration. In present study we compared and analyzed soil contamination of heavy metals in various cities/countries, and reviewed background, impact and remediation methods of soil heavy metal contamination worldwide.

Impact of baseline covariates on the immunogenicity of the 9-valent HPV vaccine - A combined analysis of five phase III clinical trials

DEFF Research Database (Denmark)

Petersen, Lone K; Restrepo, Jaime; Moreira, Edson D

2017-01-01

BACKGROUND: The immunogenicity profile of the 9-valent HPV (9vHPV) vaccine was evaluated across five phase III clinical studies conducted in girls and boys 9-15 years of age and young women 16-26 years of age. The effect of baseline characteristics of subjects on vaccine-induced HPV antibody...... responses was assessed. METHODS: Immunogenicity data from 11,304 subjects who received ≥1 dose of 9vHPV vaccine in five Phase III studies were analyzed. Vaccine was administered as a 3-dose regimen. HPV antibody titers were assessed 1 month after dose 3 using a competitive Luminex immunoassay and summarized...... as geometric mean titers (GMTs). Covariates examined were age, gender, race, region of residence, and HPV serostatus and PCR status at day 1. RESULTS: GMTs to all 9 vaccine HPV types decreased with age at vaccination initiation, and were otherwise generally similar among the demographic subgroups defined...

White organic light-emitting diodes with 4 nm metal electrode

Science.gov (United States)

Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Gather, Malte C.; Reineke, Sebastian

2015-10-01

We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

Sensitivity of ecological soil-screening levels for metals to exposure model parameterization and toxicity reference values.

Science.gov (United States)

Sample, Bradley E; Fairbrother, Anne; Kaiser, Ashley; Law, Sheryl; Adams, Bill

2014-10-01

Ecological soil-screening levels (Eco-SSLs) were developed by the United States Environmental Protection Agency (USEPA) for the purposes of setting conservative soil screening values that can be used to eliminate the need for further ecological assessment for specific analytes at a given site. Ecological soil-screening levels for wildlife represent a simplified dietary exposure model solved in terms of soil concentrations to produce exposure equal to a no-observed-adverse-effect toxicity reference value (TRV). Sensitivity analyses were performed for 6 avian and mammalian model species, and 16 metals/metalloids for which Eco-SSLs have been developed. The relative influence of model parameters was expressed as the absolute value of the range of variation observed in the resulting soil concentration when exposure is equal to the TRV. Rank analysis of variance was used to identify parameters with greatest influence on model output. For both birds and mammals, soil ingestion displayed the broadest overall range (variability), although TRVs consistently had the greatest influence on calculated soil concentrations; bioavailability in food was consistently the least influential parameter, although an important site-specific variable. Relative importance of parameters differed by trophic group. Soil ingestion ranked 2nd for carnivores and herbivores, but was 4th for invertivores. Different patterns were exhibited, depending on which parameter, trophic group, and analyte combination was considered. The approach for TRV selection was also examined in detail, with Cu as the representative analyte. The underlying assumption that generic body-weight-normalized TRVs can be used to derive protective levels for any species is not supported by the data. Whereas the use of site-, species-, and analyte-specific exposure parameters is recommended to reduce variation in exposure estimates (soil protection level), improvement of TRVs is more problematic. © 2014 The Authors

Process technology - rare and refractory metals

International Nuclear Information System (INIS)

Gupta, C.K.; Bose, D.K.