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Sample records for high copper amalgam

  1. High Copper Amalgam Alloys in Dentistry

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    Gaurav Solanki

    2012-07-01

    Full Text Available Amalgam Restoration is an example of the material giving its name to the process. Amalgam fillings are made up of mercury, powdered silver and tin. They are mixed and packed into cavities in teeth where it hardens slowly and replaces the missing tooth substance. The high copper have become material of choice as compared to low copper alloys nowadays because of their improved mechanical properties, corrosion resistance, better marginal integrity and improved performance in clinical trial. The high copper amalgam was used as a restorative material. The application of high copper amalgam was found to be much more useful than low copper amalgam. High copper had much more strength, corrosion resistance, durability and resistance to tarnish as compared to low copper amalgams. No marked expansion or condensation was noted in the amalgam restoration after its setting after 24 hrs. By using the high copper alloy, the chances of creep were also minimized in the restored tooth. No discomfort or any kind of odd sensation in the tooth was noted after few days of amalgam restoration in the tooth.

  2. Chemical characterization of selected high copper dental amalgams using XPS and XRD techniques

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    Talik, E. [A. Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)]. E-mail: talik@us.edu.pl; Babiarz-Zdyb, R. [A. Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Dziedzic, A. [Medical University of Silesia, Department of Conservative Dentistry and Periodontology, Akademicki 17 Sqr., 41-209 Bytom (Poland)

    2005-08-02

    The study was carried out to analyze some dependencies between the composition of seven high copper dental amalgams and mercury release behavior, as well as oxygen reactivity of metallic elements. Chemical comparative analysis of selected dental amalgams was carried out using X-ray photoelectron spectroscopy (XPS) technique and X-ray diffraction (XRD) method. The X-ray powder diffraction measurements revealed two main phases for measured amalgams: {gamma}{sub 1}-(Ag{sub 2}Hg{sub 3}) and {eta}'-(Cu{sub 6}Sn{sub 5}). The amount of mercury obtained by the XPS method was lower than the value quoted in the manufacturer's literature, which suggested evaporation of mercury under the UHV conditions. A linear decrease of oxygen and carbon contamination with the growing amount of Cu and Ag was observed. The XPS analysis showed that a high Sn concentration caused less resistance to oxidation. Some of the amalgams contained some extra elements, such as Bi, In, and Zn. All samples contained lead in metallic state and oxides. The amount of Ag, Cu, Sn ingredients determines the main properties of high copper amalgams and plays an important role in mercury evaporation. High tin concentration combined with the presence of smaller amounts of silver and copper (high Sn/Ag ratio) may influence the increase of mercury vaporization.

  3. The Copper concentration variation to physical properties of high copper amalgam alloy

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    Aminatun Aminatun

    2006-09-01

    Full Text Available The function of copper (Cu inside amalgam is to increase hardness and impact force and to decrease thermal expansion coefficient. In general, amalgam which is used in dentistry and available in the market is contain Cu 22%, while the maximum Cu concentration is 30%. It is necessary to determine the concentration Cu does generate the best physical properties to be used as dental restorative agent. Amalgam is made by mixing blended-metal Ag-Sn-Cu (with Cu concentration of 13%, 21%, 22%, and 29% and Hg, stirred manually in a bowl for 15 minutes,leave it in temperature 27°C for 24 hours to become hardened. The result of X-Ray Diffractometer (XRD, analyzed by Rietveld method and Rietica program, shows amalgam with Cu 29% concentration for Cu3Sn compound density is 31.790 sma/Å3, for Ag2Hg3 compound is 41.733 sma/ Å3, a Cu3Sn relative weight percentage of 43.23%, Ag2Hg3 of 54.54%, Cu 7Hg6 of 2.23% and hardness of Cu 29% is 90.700 ± 0.005 kgf/mm2. These numbers are the highest values on Cu 29% concentrations compared to other copper concentration variants. Whereas amalgam thermal expansion coefficient on Cu 29% is (2.17 ± 0.9110-3 mm/°C is the lowest value compared to other Cu concentration. The conclution is that adding Cu concentration into amalgam will increase density value, Cu3Sn relative weight percentage, hardness level and will decrease amalgam thermal expansion coefficient. Amalgam 29% Cu concentration has better physical properties compared to amalgam Cu 22% concentration.

  4. Comparison of microleakage in high copper spherical amalgam restorations using three different dentin bondin systems

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    Yasini E.

    2008-11-01

    Full Text Available "nBackground and Aim: Amalgam is one of the mostly used restorative materials, but has some disadvantages. Microleakage is one of the short comings of amalgam which may lead to sensitivity and recurrent caries. The aim of this study was to evaluate the effect of three dentin bonding systems on reduction of microleakage in amalgam restorations. "nMaterials and Methods: Class II amalgam restorations were made in 40 noncarious molar and premolar teeth. Then the specimens were divided into four equal groups. Scotch Bond Multi Purpose, Single bond, "niBond, were used as liner in groups one to three respectively and in group four no liner was used. The teeth were restored with high copper spherical amalgam. After thermocycling for 500 cycles at 50C and 550C, the specimens were immersed in basic fuchsin for 24 hours, bisectioned mesiodistally and evaluated under stereomicroscope at X25 for dye penetration. The data were analyzed by Kruskal-wallis and Scheffe. P<0.05 was considered as the level of significance. "nResults: The groups showed significant difference (p=0.003. The group four had significantly less microleakage than the first and second groups (p<0.05. The second and third groups showed significantly different microleakage (p=0.038. "nConclusion: Based on the results of this investigation applying dentin bonding agents has no effect on reducing microleakage in amalgam restorations, however more studies are recommended.

  5. Effect of Self-etch Adhesives on Self-sealing Ability of High-Copper Amalgams

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    Moazzami, Saied Mostafa; Moosavi, Horieh; Moddaber, Maryam; Parvizi, Reza; Moayed, Mohamad Hadi; Mokhber, Nima; Meharry, Michael; B Kazemi, Reza

    2016-01-01

    Statement of the Problem: Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface. Purpose: The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs). Materials and Method: Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR)/ liner/ None (No), on the cavity floor. The first main group was left without an AR/ liner (No). In the other main groups, the types of AR/ liner used were I-Bond (IB), Clearfil S3 (S3), Single Bond (SB) and Varnish (V). Each main group (n=6) was divided into two subgroups (n=3) according to the types of the amalgams used, either admixed ANA 2000 (ANA) or spherical Tytin (Tyt). The ECTs, Open Circuit Potential (OCP), and the Linear Polarization Resistance (LPR) for each sample were performed and measured 48 hours after the completion of the samples. Results: The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate) and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates). Conclusion: Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams. PMID:27942548

  6. Effect of Self-etch Adhesives on Self-sealing Ability of High-Copper Amalgams

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    Saied Mostafa Moazzami

    2016-12-01

    Full Text Available Statement of the Problem: Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface. Purpose: The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs. Materials and Method: Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR/ liner/ None (No, on the cavity floor. The first main group was left without an AR/ liner (No. In the other main groups, the types of AR/ liner used were I-Bond (IB, Clearfil S3 (S3, Single Bond (SB and Varnish (V. Each main group (n=6 was divided into two subgroups (n=3 according to the types of the amalgams used, either admixed ANA 2000 (ANA or spherical Tytin (Tyt. The ECTs, Open Circuit Potential (OCP, and the Linear Polarization Resistance (LPR for each sample were performed and measured 48 hours after the completion of the samples. Results: The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates. Conclusion: Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams. Keywords ● Electrochemical Test ● Dental Amalgam ● Corrosion ● Self-etch adhesive;

  7. Copper allergy from dental copper amalgam?

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    Gerhardsson, Lars; Björkner, Bert; Karlsteen, Magnus; Schütz, Andrejs

    2002-05-06

    A 65-year-old female was investigated due to a gradually increasing greenish colour change of her plastic dental splint, which she used to prevent teeth grinding when sleeping. Furthermore, she had noted a greenish/bluish colour change on the back of her black gloves, which she used to wipe her tears away while walking outdoors. The investigation revealed that the patient had a contact allergy to copper, which is very rare. She had, however, had no occupational exposure to copper. The contact allergy may be caused by long-term exposure of the oral mucosa to copper from copper-rich amalgam fillings, which were frequently used in childhood dentistry up to the 1960s in Sweden. The deposition of a copper-containing coating on the dental splint may be caused by a raised copper intake from drinking water, increasing the copper excretion in saliva, in combination with release of copper due to electrochemical corrosion of dental amalgam. The greenish colour change of the surface of the splint is probably caused by deposition of a mixture of copper compounds, e.g. copper carbonates. Analysis by the X-ray diffraction technique indicates that the dominant component is copper oxide (Cu2O and CuO). The corresponding greenish/bluish discoloration observed on the back of the patient's gloves may be caused by increased copper excretion in tears.

  8. Making High-Tensile-Strength Amalgam Components

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    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  9. Comparison of tarnish level in two types of high- copper dental amalgams with lathe-cut and spherical particles produced in Iran

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    Mosavi-nasab SM.

    2001-09-01

    Full Text Available "nAbstract: There are two types of high-copper dental amalgams produced in Iran; Cinalloy (lathe-cut particles and Cinalux (spherical particles. Tarnish is one of the disadvantages of dental amalgam, which precedes corrosion, and in fact it means real destruction of restorative materials. The purpose of this study was to compare the extent of tarnish in Cinalux and Cinalloy amalgams. 32 patients, with at least two carious or poorly restored teeth were selected. Then, each tooth was restored with one of these two types of dental amalgams. The restorations were polished after 24 hours and patients were followed up after 9 months. The restorations were categorized in four groups of no change, one plus (1-30%, two plus (30-60% and three plus (more than 60% according to the level of discoloration. The results showed that the level of tarnish in Cinalux group was significantly less than Cinalloy group. The mean of tarnish for Cinalloy and Cinalux was 2.09±0.59 and 1.72±0.68 respectively. In addition, statistical analysis showed that there was no significant relationship between tarnish and Oral hygiene, smoking, operator or type and place of restoration.

  10. Gastrointestinal and in vitro release of copper, cadmium, indium, mercury and zinc from conventional and copper-rich amalgams

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    Brune, D. (NIOM, Scandinavian Institute of Dental Materials, Oslo, Norway); Gjerdet, N. (Department of Dental Materials, School of Dentistry, Bergen, Norway); Paulsen, G. (Denatal Faculty, University of Oslo, Norway)

    1983-01-01

    Particles of a conventional lathe-cut, a spherical non-gamma 2 and a copper amalgam have been gastrointestinally administered to rats for the purpose of evaluation of the dissolution resistance. The animals were sacrificed after 20 hrs. The contents of copper, cadmium, indium, mercury and zinc in kidney, liver, lung or blood were measured using nuclear tracer techniques. From a copper amalgam an extreme release of copper was demonstrated. This study simulates the clinical conditions of elemental release from swallowed amalgam particles after amalgam insertion or after removal of old amalgam fillings. Specimens of the same types of amalgams were also exposed to artificial saliva for a period of 10 days. The amounts of copper and mercury released were measured with flame and flameless atomic absorption spectrophotometry respectively. The levels of copper and mercury released from the copper amalgam were approximately 50 times those of the two other amalgam types studied.

  11. Cathodic stripping voltammetry of cysteine using silver and copper solid amalgam electrodes.

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    Yosypchuk, B; Novotný, L

    2002-04-01

    Silver and copper solid amalgam electrodes (modified with mercury meniscus and based on amalgamation of fine metallic powder) have been successfully tested for cathodic stripping voltammetry of cysteine. In the case of the silver solid amalgam electrode AgSAE the relative standard deviation (RSD) and the detection limit (3 SD) reached +/-2.3% and 3x10(-9) mol l(-1) cysteine, respectively.

  12. Dependence of kinetic variables in the short-term release of Hg2+, Cu2+ and Zn2+ ions into synthetic saliva from an high-copper dental amalgam.

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    Campus, Guglielmo; Garcia-Godoy, Franklin; Gaspa, Leonardo; Panzanelli, Angelo; Piu, Paola C; Micera, Giovanni; Lugliè, Pierfranca; Sanna, Gavino

    2007-08-01

    The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva.

  13. Copper-nickel-rich, amalgamated ferromanganese crust-nodule deposits from Shatsky Rise, NW Pacific

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    Hein, J.R.; Conrad, T.A.; Frank, M.; Christl, M.; Sager, W.W.

    2012-01-01

    A unique set of ferromanganese crusts and nodules collected from Shatsky Rise (SR), NW Pacific, were analyzed for mineralogical and chemical compositions, and dated using Be isotopes and cobalt chronometry. The composition of these midlatitude, deep-water deposits is markedly different from northwest-equatorial Pacific (PCZ) crusts, where most studies have been conducted. Crusts and nodules on SR formed in close proximity and some nodule deposits were cemented and overgrown by crusts, forming amalgamated deposits. The deep-water SR crusts are high in Cu, Li, and Th and low in Co, Te, and Tl concentrations compared to PCZ crusts. Thorium concentrations (ppm) are especially striking with a high of 152 (mean 56), compared to PCZ crusts (mean 11). The deep-water SR crusts show a diagenetic chemical signal, but not a diagenetic mineralogy, which together constrain the redox conditions to early oxic diagenesis. Diagenetic input to crusts is rare, but unequivocal in these deep-water crusts. Copper, Ni, and Li are strongly enriched in SR deep-water deposits, but only in layers older than about 3.4 Ma. Diagenetic reactions in the sediment and dissolution of biogenic calcite in the water column are the likely sources of these metals. The highest concentrations of Li are in crust layers that formed near the calcite compensation depth. The onset of Ni, Cu, and Li enrichment in the middle Miocene and cessation at about 3.4 Ma were accompanied by changes in the deep-water environment, especially composition and flow rates of water masses, and location of the carbonate compensation depth.

  14. Amalgam tattoo.

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    Tran, Hien T; Anandasabapathy, Niroshana; Soldano, Anthony C

    2008-05-15

    A 53-year-old woman with a history of melanoma status-post excision two years prior presented with a 4-month history of 4, dark-brown macules on the inferior surface of her tongue. A biopsy specimen showed a squamous mucosa with chronic submucosal inflammation and brown pigment. The clinical and histopathologic findings were consistent with a diagnosis of amalgam tattoo. Amalgam tattoos are common, oral pigmented lesions that clinically present as isolated, blue, grey, or black macules on the gingivae, the buccal and alveolar mucosae, the palate, and/or the tongue. They are due to deposition of a mixture of silver, tin, mercury, copper, and zinc, which are components of an amalgam filling, into the oral soft tissues. Amalgam tattoos can either be treated surgically or with a Q-switched ruby laser. In the case of our patient with the history of melanoma, her oral lesions proved not to be the more dire diagnosis of malignant melanoma.

  15. Effect of pellicle on galvanic corrosion of amalgam.

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    Holland, R I

    1984-02-01

    Galvanic corrosion of amalgam, induced by contact with a type IV dental casting gold alloy, was determined under simulated oral conditions in an electrochemical cell. The effect of a pellicle layer formed by 1 h exposure to saliva in the oral cavity was determined. Pellicle on the amalgam had no effect on the maximum corrosion rate or the 2 h corrosion charge, whereas pellicle on the gold alloy substantially reduced both these parameters of the conventional low-copper amalgam; the corrosion of the high-copper amalgam was less and was not influenced by pellicle formation.

  16. 21 CFR 872.3100 - Dental amalgamator.

    Science.gov (United States)

    2010-04-01

    ... amalgamator is a device, usually AC-powered, intended to mix, by shaking, amalgam capsules containing mercury and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam...

  17. Microanalysis of oligodeoxynucleotides by cathodic stripping voltammetry at amalgam-alloy surfaces in the presence of copper ions.

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    Hason, Stanislav; Vetterl, Vladimír

    2006-05-15

    The application of gold amalgam-alloy electrode (AuAE) for a sensitive voltammetric detection of different oligodeoxynucleotides (ODNs) containing the purine units within the ODN-chains in the presence of copper is described. The detection of ODNs is based on the following procedure: (i) the first step includes an acidic hydrolysis of the ODN (ahODN) samples performing the release of the purine bases from ODN-chain; (ii) the second step includes an electrochemical accumulation of the complex of the purine base residues released from ODN-chain with copper ions Cu(I) (ahODN-Cu(I) complex) at the potential of reduction of copper ions Cu(II) on the amalgam-alloy electrode surfaces; (iii) finally followed the cathodic stripping of the electrochemically accumulated ahODN-Cu(I) complex from the electrode surface. The proposed electrochemical method was used for: (a) detection of different ODN lengths containing only adenine units (the number of adenine units within the ODN-chains was changed from 10 to 80), and (b) determination of the number of purine units within the 30-mer ODNs containing a random sequence segments involving both the purine and pyrimidine units. The intensity of the cathodic stripping current density peak (j(CSP)) of the electrochemically accumulated ahODN-Cu(I) complex increased linearly with the increasing number of purine units within the ODN-chains. We observed a good correlation between the percentage content of purine units to the whole length of different 30-mer ODNs and the percentage content of the intensity of the j(CSP) of the electrochemically accumulated 30-mer ahODN-Cu(I) complexes. The detection of acid hydrolysed 80-mer (A(80)) in the bulk solution and in a 20-mul volume is possible down to 200pM and 2nM at the AuAE, respectively. For the shortest 10-mer (A(10)) a detectable value of 5nM in the bulk solution on the AuAE was observed. The sensitive detection of different ODNs containing the purine units in their chains in the presence of

  18. Comparison of the composition of Cinalux amalgam with ADA standard

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    Moosavi Nasab M

    2002-07-01

    Full Text Available Dental amalgam is one of the oldest restorative materials, used in dentistry, which has undergone a lot of quality changes since its advent. Copper is one of the major elements in dental amalgam. Dental amalgam is classified as low and high cooper group based on the percentage of this element. Cinaluy is an Iranian product, a product of Shahid Faghihi's factory and its particles are spherical with high copper and it does not contain any zinc and gama II phase. The goal of this study was to identify the type and percentage of its ingredients and to analyze this dental amalgam by muclear reactor. The products of the factory, at two different times, were compared with each other and also with the percentages presented by the factory, regarding their ingredients. They were also compared with two standardized amalgams called: Sybralloy and Tytin. Three typical Cinalux amalgam capsules, produced on different dates, were selected. The contents of capsules were enveloped in plastic bags and then sealed and placed in a miniature reactor to undergo nuclear radiation for 10 days. After this period, the elements in amalgam became activated and converted into radioisotopes of the same elements, and began to radiate. Then gama spectrometer system accumulated these radiations and transferred them to Span software. This software, aided by reference standards, shows the intensity and the wave length of the received radiation, and consequently identifies the type and percentage of the elements in amalgam. The results demonstrated that the Cinalux amalgam samples, regarding the type and percentage of their elements, were identical and also met the factory standards. The differences were not significant. There was also no significant difference between Cinalux amalgam and the standardized amalgam Sybralloy, regarding the percentage of their elements, but comparing this amalgam with the standardized amalgam Tytin, a significant difference was not observed.

  19. Pengaruh Penambahan Paladium Terhadap Perilaku Thermal Amalgam Tembaga Tinggi Tipe Lathe Cut

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    Ellyza Herda

    2015-09-01

    Full Text Available Effects of additing 1 percent (w/o palladium (Pd on the thermal behavior of a lathe cut type high copper amalgam (13 w/o copper were studied. The identical alloys, with and without 1% Pd were fabricated. X-ray diffraction studies of the amalgams revealed the elimination of the γ2-phase by Pd addition DSC thermogram of non-Pd containing amalgam indicated the existence of two γ1-phaseone with the transition temperature (endothermic peak at 88◦C and the other at 109◦C. The thermogram data of the Pd containing amalgam showed an endothermic peak at 110.7◦C. The transition temperature of the n phase of the palladium containing amalgam is 4.9◦C lower than the transition temperature of the n phase of the non Pd containing amalgam. This result indicates that the n phase of the Pd containing amalgam includes more of Tin (Sn than the non-Pd containing amalgam. The thermogravimetri diagram showed that the phase decomposition occurred at about 390◦C for the non-Pd containing amalgam and at about 410◦C for the Pd containing amalgam. It is concluded that the addition of 1% Pd into a lathe cut type of high copper amalgam (13% could eliminate the formation of γ2 phase as well as an unstable γ1 phase, promoting strong mercury bonding to Silver.

  20. Dental Amalgam

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    ... Products and Medical Procedures Dental Devices Dental Amalgam Dental Amalgam Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Dental amalgam is a dental filling material which is ...

  1. High-Field MRI and Mercury Release from Dental Amalgam Fillings

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    SMJ Mortazavi

    2014-04-01

    Full Text Available Mercury is among the most toxic nonradioactive elements which may cause toxicity even at low doses. Some studies showed release of mercury from dental amalgam fillings in individuals who used mobile phone. This study was conducted to assess the effect of high-field MRI on mercury release from dental amalgam filling. We studied two groups of students with identical tooth decays requiring a similar pattern of restorative dentistry. They were exposed to a magnetic flux density of 1.5 T produced by a MRI machine. 16 otherwise healthy students with identical dental decay participated in this study. They underwent similar restorative dentistry procedures and randomly divided into two groups of MRI-exposed and control arms. Urinary concentrations of mercury in the control subjects were measured before (hour 0 and 48 and 72 hrs after amalgam restoration, using cold vapor atomic absorption spectrometry. Urinary concentrations of mercury in exposed individuals were determined before (hour 0, and 24, 48, 72 and 96 hrs after amalgam restoration. Unlike control subjects, they underwent conventional brain MRI (15 min, 99 slices, 24 hrs after amalgam restoration. The mean±SD urinary mercury levels in MRI-exposed individuals increased linearly from a baseline value of 20.70±17.96 to 24.83±22.91 μg/L 72 hrs after MRI. In the control group, the concentration decreased linearly from 20.70±19.77 to 16.14±20.05 μg/L. The difference between urinary mercury in the exposed and control group, 72 hrs after MRI (96 h after restoration,was significant (p=0.046. These findings provide further support for the noxious effect of MRI (exposure to strong magnetic fieldand release of mercury from dental amalgam fillings.

  2. High-field MRI and mercury release from dental amalgam fillings.

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    Mortazavi, S M J; Neghab, M; Anoosheh, S M H; Bahaeddini, N; Mortazavi, G; Neghab, P; Rajaeifard, A

    2014-04-01

    Mercury is among the most toxic nonradioactive elements which may cause toxicity even at low doses. Some studies showed release of mercury from dental amalgam fillings in individuals who used mobile phone. This study was conducted to assess the effect of high-field MRI on mercury release from dental amalgam filling. We studied two groups of students with identical tooth decays requiring a similar pattern of restorative dentistry. They were exposed to a magnetic flux density of 1.5 T produced by a MRI machine. 16 otherwise healthy students with identical dental decay participated in this study. They underwent similar restorative dentistry procedures and randomly divided into two groups of MRI-exposed and control arms. Urinary concentrations of mercury in the control subjects were measured before (hour 0) and 48 and 72 hrs after amalgam restoration, using cold vapor atomic absorption spectrometry. Urinary concentrations of mercury in exposed individuals were determined before (hour 0), and 24, 48, 72 and 96 hrs after amalgam restoration. Unlike control subjects, they underwent conventional brain MRI (15 min, 99 slices), 24 hrs after amalgam restoration. The mean±SD urinary mercury levels in MRI-exposed individuals increased linearly from a baseline value of 20.70±17.96 to 24.83±22.91 μg/L 72 hrs after MRI. In the control group, the concentration decreased linearly from 20.70±19.77 to 16.14±20.05 μg/L. The difference between urinary mercury in the exposed and control group, 72 hrs after MRI (96 h after restoration),was significant (p=0.046). These findings provide further support for the noxious effect of MRI (exposure to strong magnetic field)and release of mercury from dental amalgam fillings.

  3. Galvanic corrosion and cytotoxic effects of amalgam and gallium alloys coupled to titanium.

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    Bumgardner, J D; Johansson, B I

    1996-06-01

    The aim of this study was to examine and compare the galvanic corrosion of a conventional, a dispersed high-copper, and a palladium-enriched spherical high-copper amalgam and a gallium alloy coupled to titanium in saline and cell culture solutions, and to evaluate the effects of the couples on cultured cells. The potentials and charge transfers between amalgams and titanium were measured by electrochemical corrosion methods. Cytotoxicity of the couples, as indicated by the uptake of neutral red vital stain, was determined in 24-h direct contact human gingival fibroblast cell cultures. Results of this study indicated that before connecting the high-copper amalgams to titanium, the amalgams exhibited more positive potentials which resulted in initial negative charge transfers, i.e. corrosion of titanium. However, this initial corrosion appeared to cause titanium to passivate, and a shift in galvanic currents to positive charge transfers, i.e. corrosion of the amalgam samples. Lower galvanic currents were measured for the amalgam-titanium couples as compared to the gallium alloy-titanium couple. Coupling the conventional or the palladium-enriched high-copper amalgams to titanium did not significantly affect the uptake of neutral red as compared to cells not exposed to any test alloy. However, significant cytotoxic effects were observed when the dispersed-type high-copper amalgam and the gallium alloy were coupled to titanium. Even though the corrosion currents measured for these couples were less than gold alloys coupled to amalgam, these results suggest there is the potential for released galvanic corrosion products to become cytotoxic. These data warrant further investigations into the effects of coupling amalgam and gallium alloys to titanium in the oral environment.

  4. An In Vitro Evaluation of the Use of Resin Liners to Reduce Microleakage and Improve Bond Strength of Amalgam Restorations

    Science.gov (United States)

    1991-01-01

    of amalgam, gutta percha, and zinc oxide- eugenol , found that the dyes possessed many of the advantages noted by other researchers. The ability of...Clin North Am 1985;29:341-58. 4. Glassman MD, Miller IJ. Antibacterial properties of one conventional and three high-copper dental amalgams. J Prosthet

  5. Comparison of release of mercury from three dental amalgams.

    Science.gov (United States)

    Chew, C L; Soh, G; Lee, A S; Yeoh, T S

    1989-07-01

    Mercury release from dental amalgams has generated considerable concern in recent years and is the subject of this study. Specimens of one admixed high-copper amalgam (Contour), one lathe-cut low-copper amalgam (SDI), and a new tin- and copper-free amalgam claimed to be non-mercury-releasing (Composil) were evaluated for release of mercury when incubated in purified water at 37 degrees C. Measurement of mercury was done by cold-vapor atomic absorption spectrophotometry, and the amount released was expressed as micrograms/cm2/24 hr. Study was conducted over a four-week period. Results show that Contour and SDI released similar insignificant amounts (mean release of less than 0.1 microgram/cm2/24 hr) compared with Composil (mean release of 41.0 micrograms/cm2/24 hr). The difference in release by Composil compared with that by Contour and SDI is highly significant (P less than 0.001). The implications of chronic release of mercury from dental amalgams are discussed. Long-term release studies are in progress.

  6. About Dental Amalgam Fillings

    Science.gov (United States)

    ... and Medical Procedures Dental Devices Dental Amalgam About Dental Amalgam Fillings Share Tweet Linkedin Pin it More ... should I have my fillings removed? What is dental amalgam? Dental amalgam is a dental filling material ...

  7. Dentalni amalgam

    OpenAIRE

    Galić, Nada; Šutalo, Jozo; Prpić-Mehičić, Goranka; Anić, Ivica

    1994-01-01

    Dentalni amalgam je bio materijal izbora za ispune na stražnjim zubima tijekom proteklih 150 godina. U radu je prikazan p o vijesni razvoj amalgama, njegov obvezni sastav, te podjela dentalnih amalgama prema količinskom udjelu bakra i prema obliku čestica. Navedena su svojstva amalgama s posebnim osvrtom na njegovu toksičnost. Poznato je da se posljednjih godina pojačao napad na amalgam i u znanstvenoj i u popularnoj literaturi, a u svezi s njegovim navodnim patološkim djelovanjem ...

  8. Theoretical models of mercury dissolution from dental amalgams in neutral and acidic flows

    Science.gov (United States)

    Keanini, Russell G.; Ferracane, Jack L.; Okabe, Toru

    2001-06-01

    This article reports an experimental and theoretical investigation of mercury dissolution from dental amalgams immersed in neutral (noncorrosive) and acidic (corrosive) flows. Atomic absorption spectrophotometric measurements of Hg loss indicate that in neutral flow, surface oxide films formed in air prior to immersion persist and effectively suppress significant mercury release. In acidic (pH 1) flows, by contrast, oxide films are unstable and dissolve; depending on the amalgam’s material composition, particularly its copper content, two distinct mercury release mechanisms are initiated. In low copper amalgam, high initial mercury release rates are observed and appear to reflect preferential mercury dissolution from unstable Sn8Hg ( γ 2) grains within the amalgam matrix. In high copper amalgam, mercury release rates are initially low, but increase with time. Microscopic examination suggests that this feature reflects corrosion of copper from grains of Cu6Sn5 ( η') and consequent exposure of Ag2Hg3 ( γ 1) grains; the latter serve as internal mercury release sites and become more numerous as corrosion proceeds. Three theoretical models are proposed in order to explain observed dissolution characteristics. Model I, applicable to high and low copper amalgams in neutral flow, assumes that mercury dissolution is mediated by solid diffusion within the amalgam, and that a thin oxide film persists on the amalgam’s surface and lumps diffusive in-film transport into an effective convective boundary condition. Model II, applicable to low copper amalgam in acidic flow, assumes that the amalgam’s external oxide film dissolves on a short time scale relative to the experimental observation period; it neglects corrosive suppression of mercury transport. Model III, applicable to high copper amalgam in acidic flow, assumes that internal mercury release sites are created by corrosion of copper in η' grains and that corrosion proceeds via an oxidation-reduction reaction

  9. Irregular amalgams

    Directory of Open Access Journals (Sweden)

    James Stewart

    1986-01-01

    Full Text Available The amalgam of Lp and ℓq consists of those functions for which the sequence of Lp-norms over the intervals [n,n+1 is in ℓq. These spaces (Lp,ℓq have been studied in several recent papers. Here we replace the intervals [n,n+1 by a cover α={In;n∈Z} of the real line consisting of disjoint half-open intervals In each of the form [a,b, and investigate which properties of (Lp,ℓq carry over to these irregular amalgams (Lp,ℓqα. In particular, we study how (Lp,ℓqα varies as p, q, and α vary and determine conditions under which translation is continuous.

  10. Kondensasi Pada Dental Amalgam

    OpenAIRE

    Batubara, Runi Syahriani

    2011-01-01

    Amalgam merupakan campuran dari dua atau beberapa logam (alloy) yang salah satunya adalah merkuri. Kata amalgam juga didefenisikan untuk menggambarkan kombinasi atau campuran dari beberapa bahan seperti merkuri, perak, timah, tembaga, dan lainnya. Dental amalgam sendiri adalah kombinasi alloy dengan merkuri melalui suatu proses yang disebut amalgamasi. Pemanipulasian amalgam meliputi triturasi, kondensasi, carving, dan polishing. Kondensasi merupakan penekanan amalgam setelah triturasi p...

  11. Study of Copper Substitute in High Copper Price Market Environment

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>The high price of copper drives up industry cost,also it is difficult for terminal products to raise price to transfer the cost pressure brought by increase in copper price,as a result downstream consumption markets instead try to seek

  12. Is high-viscosity glass-ionomer-cement a successor to amalgam for treating primary molars?

    NARCIS (Netherlands)

    Hilgert, L.A.; Amorim, R.G. de; Leal, S.C.; Mulder, J.; Creugers, N.H.; Frencken, J.E.

    2014-01-01

    OBJECTIVES: To assess and compare the cumulative survival rate of amalgam and atraumatic restorative treatment (ART) restorations in primary molars over 3 years. METHODS: 280 children aged 6-7 years old were enrolled in a cluster randomized controlled clinical trial using a parallel group design cov

  13. 中国古青铜器表面富锡铜鎏镀及鎏焊的工艺探索第三部分——鎏焊%Technological study on amalgam coating and brazing of tin-rich copper on surface of bronze wares of ancient China——Part Ⅲ.Amalgam brazing

    Institute of Scientific and Technical Information of China (English)

    吴元康; 储荣邦

    2012-01-01

    Amalgam brazing is derived from amalgam coating. The definition, characteristics, application, and significance of amalgam brazing were expatiated. A process of amalgam brazing for producing combined bronze wares was developed. The compositions of brazing material and flux were given. The operations of pretreatment, mercury removal by heating, and post-treatment were described. The implementation of amalgam coating and brazing processes was introduced taking the Western Han Dynasty's bronze cowry container with tribute-paying figures excavated in Yunnan as an example. The method for distinguishing whether an antique bronze ware is produced by cast welding after lost-wax casting or by copper brazing with separated small cast parts was presented.%鎏焊是从鎏镀衍生而来的.阐述了鎏焊的定义、特点、应用和意义.设计了用于制作组合青铜器的鎏焊工艺,给出了焊料、焊剂配方,说明了前处理、加热驱汞及后处理的操作方法.以西汉云南纳贡场面青铜贮贝器为例,介绍了鎏镀与鎏焊工艺的具体实施过程.提出了鉴别古青铜器是由失蜡铸造后铸焊而成还是由分铸小件铜焊而成的方法.

  14. Determination of the cathode and anode voltage drops in high power low-pressure amalgam lamps

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyak, L. M., E-mail: vasilyak@ihed.ras.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Vasiliev, A. I., E-mail: vasiliev@npo.lit.ru; Kostyuchenko, S. V.; Sokolov, D. V.; Startsev, A. Yu. [Joint Stock Company NPO LIT (Russian Federation); Kudryavtsev, N. N. [Moscow Institute of Physics and Technology (State University) (Russian Federation)

    2011-12-15

    For the first time, cathode and anode drops of powerful low-pressure amalgam lamps were measured. The lamp discharge current is 3.2 A, discharge current frequency is 43 kHz, linear electric power is 2.4 W/cm. The method of determination of a cathode drop is based on the change of a lamp operating voltage at variation of the electrode filament current at constant discharge current. The total (cathode plus anode) drop of voltage was measured by other, independent ways. The maximum cathode fall is 10.8 V; the anode fall corresponding to the maximal cathode fall is 2.4 V. It is shown that in powerful low pressure amalgam lamps the anode fall makes a considerable contribution (in certain cases, the basic one) to heating of electrodes. Therefore, the anode fall cannot be neglected, at design an electrode and ballast of amalgam lamps with operating discharge current frequency of tens of kHz.

  15. 中国古青铜器表面富锡铜鎏镀及鎏焊的工艺探索 第一部分——富锡铜鎏镀在古青铜器中的应用%Technological study on amalgam coating and brazing of tin-rich copper on surface of bronze wares of ancient China—Part Ⅰ.Application of amalgam coating of tin-rich copper in ancient bronze wares

    Institute of Scientific and Technical Information of China (English)

    吴元康; 储荣邦

    2012-01-01

    The ancient bronze wares with Sn-rich copper coatings on their surfaces were introduced based on the archaeological findings in China. The definition and classification of amalgam coating were described. It is pointed out that most ancient bronze wares were treated by amalgam coating of Sn-rich copper, not by hot-dip plating or other processes. The removal of Hg by heating after amalgam coating and the decomposition of Sn7-9Hg in soil lead to the fact that Hg is undetectable on the surface of ancient bronze wares.%根据出土文物的情况,介绍了表面具有富锡铜层的古青铜器.阐述了鎏镀的定义及分类.指出古青铜器大多经过富锡铜鎏镀工艺处理,而不是热浸镀或其他工艺.认为鎏镀后加热驱汞及Sn7-9Hg在土壤环境中分解,是导致古青铜器表面测不出汞的原因.

  16. Ultrasensitive and highly selective detection of bioaccumulation of methyl-mercury in fish samples via Ag⁰/Hg⁰ amalgamation.

    Science.gov (United States)

    Deng, Li; Li, Yan; Yan, Xiuping; Xiao, Jun; Ma, Cheng; Zheng, Jing; Liu, Shaojun; Yang, Ronghua

    2015-02-17

    Methylmercury (CH3Hg(+)), the common organic source of mercury, is well-known as one of the most toxic compounds that is more toxic than inorganic or elemental mercury. In seabeds, the deposited Hg(2+) ions are converted into CH3Hg(+) by bacteria, where they are subsequently consumed and bioaccumulated in the tissue of fish, and finally, to enter the human diet, causing severe health problems. Therefore, sensitive and selective detection of bioaccumulation of CH3Hg(+) in fish samples is desirable. However, selective assay of CH3Hg(+) in the mercury-containing samples has been seriously hampered by the difficulty to distinguish CH3Hg(+) from ionic mercury. We report here that metal amalgamation, a natural phenomenon occurring between mercury atoms and certain metal atoms, combining with DNA-protected silver nanoparticles, can be used to detect CH3Hg(+) with high sensitivity and superior selectivity over Hg(2+) and other heavy metals. In our proposed approach, discrimination between CH3Hg(+) and Hg(2+) ions was realized by forming Ag/Hg amalgam with a CH3Hg(+)-specific scaffold. We have found that Ag/Hg amalgam can be formed on a CH3Hg(+)-specific DNA template between silver atoms and mercury atoms but cannot between silver atoms and CH3Hg(+). With a dye-labeled DNA strand, the sensor can detect CH3Hg(+) down to the picomolar level, which is >125-fold sensitive over Hg(2+). Moreover, the presence of 50-fold Hg(2+) and 10(6)-fold other metal ions do not interfere with the CH3Hg(+) detection. The results shown herein have important implications for the fast, easy, and selective detection and monitoring of CH3Hg(+) in environmental and biological samples.

  17. 中国古青铜器表面富锡铜鎏镀及鎏焊的工艺探索第二部分——鎏镀的原理及工艺设计%Technological study on amalgam coating and brazing of tin-rich copper on surface of bronze wares of ancient China—Part Ⅱ.Principle and process design of amalgam coating

    Institute of Scientific and Technical Information of China (English)

    吴元康; 储荣邦

    2012-01-01

    The major roles of Cu, Sn, Pd, and Hg in amalgam coating material, the principle of metallurgical reactions between the elements, and the phase transformation involved in the process of removing mercury by heating were described. Three formulations of Sn-rich copper powder for amalgam coating were designed to reproduce antique bronze mirrors. The pretreatment of bronze wares, the preparation of amalgam coating material and its coating method, and the operation procedure of mercury removal by heating were introduced. The reasons why the Sn-rich coatings on ancient bronze wares are produced by amalgam coating of Sn-rich copper were presented.%阐述了鎏镀料中铜、锡、铅、汞的主要作用,以及加热驱汞时各元素之间冶金反应的原理和物相变化.以仿古青铜镜为例,设计了3种鎏镀用富锡铜粉的配方,介绍了青铜件的镀前处理,汞齐涂料配制和涂抹的方法,以及加热驱汞的操作步骤.指出了古青铜器表面富锡镀层为鎏镀富锡铜的依据.

  18. Radiation resistance of copper alloys at high exposure levels

    Energy Technology Data Exchange (ETDEWEB)

    Garner, F.A. (Pacific Northwest Lab., Richland, WA (USA)); Zinkle, S.J. (Oak Ridge National Lab., TN (USA))

    1990-08-01

    Copper alloys are currently being considered for high heat flux applications in fusion power devices. A review is presented of the results of two separate series of experiments on the radiation response of copper and copper alloys. One of these involved pure copper and boron-doped copper in the ORR mixed spectrum reactor. The other series included pure copper and a wide array of copper alloys irradiated in the FFTF fast reactor 16 refs., 13 figs.

  19. Has resin-based composite replaced amalgam?

    Science.gov (United States)

    Christensen, Gordon J; Child, Paul L

    2010-02-01

    The major health organizations in the world continue to accept amalgam use, but the "amalgam war" of the 1800s is still going on. The end is not in sight. There is little disagreement that amalgam serves well and, although controversial, it appears to have minimal to no health hazards. There is a wide variation in the relative amount of amalgam placed in developed countries, and many dentists in North America do not use it. However, amalgam is still being used at least some of the time by the majority of practitioners in North America, and most of those practitioners also place resin-based composite in Class II locations. The evolution from amalgam to tooth-colored restorations has been a slow and tumultuous journey. The acceptability of resin-based composite in Class II locations continues to be a question for some dentists, while others have concluded that amalgam is "dead." It would be highly desirable if some of dentists using the alleged poisonous properties of amalgam as a "practice building" ploy would find more legitimate methods to increase their practice activity.

  20. Strength Pada Amalgam

    OpenAIRE

    Sri Handayani

    2008-01-01

    Amalgam didefinisikan sebagai campuran dari dua atau beberapa logam (alloy) yang salah satunya adalali merkuri. Dental amalgam sendiri merupakan campuran dari merkuri (Hg), perak (Ag), timah (Sn), tembaga (Cu) dan bahan-bahan lain yang memiliki fungsinya masing-masing, dimana sebagian diantaranya akan saling mengatasi kekurangan yang ditimbulkan logam lain, jika logam tersebut dikombinasikan dengan perbandingan yang tepat. Amalgam mempunyai strength (kekuatan) yang cukup besar sehingga dap...

  1. Adhesives, silver amalgam.

    Science.gov (United States)

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

  2. Jiangxi Copper and Yates Joined Hands in High-Grade Copper Foil Project Construction

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正> The construction of a large-scale copper foilproject recently started in the High-Tech De-velopment Zone of Nanchang,the capital ofJiangxi Province.This new copper foil factory,with a designed annual production capacity of6,000 tons of high-grade copper foil,is a jointventure project between Jiangxi Copper Group,the No.1 copper producer in China,and YatesInc.,a leading US copper product company andthe world’s first electrical circuit board maker.

  3. Characterization of dentin-bonding-amalgam interfaces.

    Science.gov (United States)

    Geiger, S B; Mazor, Y; Klein, E; Judes, H

    2001-01-01

    Applying a bonding agent and a resinous adhesive layer before amalgam condensation has become a common clinical procedure. However, interactions between the different interfaces formed, and the extent of sealing obtained, have not been extensively studied. This study characterized the interfaces formed in the bonded amalgam restoration. Specifically, the individual contributions of the bonding agent (One-Step) and the adhesive resin (Resinomer) were examined, along with their mode of application on the prevention of microleakage and the formation of a tight, continuous adhesion to amalgam. To this end, a dye penetration assay and scanning electron microscopy (SEM) were used, including high resolution elemental analysis, for the characterization of the sealing properties and the interface structure obtained following various procedures of applying amalgam adhesives. Results indicated that placing bonding material under the amalgam restoration is essential to preventing microleakage. When condensed against uncured or cured adhesive material, the adhesive resinous glass layer creates a thick interface with protrusions and inclusions in the amalgam, though microleakage studies indicate that condensation over the uncured adhesive results in a better seal than that of the cured adhesive. SEM combined with elemental analysis indicates that the adhesion between amalgam and adhesive material is mainly of mechanical character and is formed by interdigitations of the adhesive material protruding into the amalgam. Gaps formed at the various interfaces in the different modalities could be localized. In addition, resinous glass composite alone, without bonding, was found to provide an unacceptable degree of sealing between the tooth and amalgam. The clinical significance of these findings is further discussed.

  4. Dental amalgam: An update

    Directory of Open Access Journals (Sweden)

    Bharti Ramesh

    2010-01-01

    Full Text Available Dental amalgam has served as an excellent and versatile restorative material for many years, despite periods of controversy. The authors review its history, summarize the evidence with regard to its performance and offer predictions for the future of this material. The PubMed database was used initially; the reference list for dental amalgam featured 8641 articles and 13 publications dealing with recent advances in dental amalgam. A forward search was undertaken on selected articles and using some author names. For the present, amalgam should remain the material of choice for economic direct restoration of posterior teeth. When esthetic concerns are paramount, tooth-colored materials, placed meticulously, can provide an acceptable alternative. All alternative restorative materials and procedures, however, have certain limitations.

  5. High-strength braze joints between copper and steel

    Science.gov (United States)

    Kuhn, R. F.

    1967-01-01

    High-strength braze joints between copper and steel are produced by plating the faying surface of the copper with a layer of gold. This reduces porosity in the braze area and strengthens the resultant joint.

  6. Micro-PIXE study of metal loss from dental amalgam

    Science.gov (United States)

    Meesat, Ridthee; Sudprasert, Wanwisa; Guibert, Edouard; Wang, Liping; Chappuis, Thibault; Whitlow, Harry J.

    2017-08-01

    Mercury amalgams have been a topic of controversy ever since their introduction over 150 years ago as a dental material. An interesting question is if metals are released from the amalgam into the enamel and dentine tissue. To elucidate this PIXE mapping was used to investigate metal redistribution in an extracted molar tooth with a ∼30 year old high-Cu content amalgam filling. The tooth was sectioned and polished, and elemental mapping carried out on the amalgam/enamel, bulk amalgam and the wear surface of the amalgam. As expected, the amalgam was multiphase amalgam comprising of Cu-rich and Ag-rich grains with non-uniform distribution of Hg. The amalgam/dentine interface was clearly defined with amalgam elements on one side and C and P from hydroxyapatite on the other side with evidence of only slight interface corrosion. The peaks for Cu Hg and Zn were isolated from interfering signals with concentrations in the enamel tissue, observed to be at, or below the method detection limit. The proximity in energy of the Sn L α and Ca K α , peaks and the background on the Hg M α gave signal overlap which increased the MDL for these elements. Remarkably, a course grain texture in the amalgam was observed just below the biting surface of the amalgam which might be associated with tribochemical processes from mastication. This coupled with the clear absence of the amalgam metals from tooth tissue, even in close proximity to the interface, suggests that for this sample, release of Hg occurred via erosion or dissolution in saliva.

  7. Phase down of amalgam

    Science.gov (United States)

    AL-Rabab’ah, Mohammad A.; Bustani, Mohammad A.; Khraisat, Ameen S.; Sawair, Faleh A.

    2016-01-01

    Objectives To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites. Methods This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite. Results Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists’ decision to remove old amalgam based on patient’s demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education. PMID:27874155

  8. Integrated starting and running amalgam assembly for an electrodeless fluorescent lamp

    Science.gov (United States)

    Borowiec, Joseph Christopher; Cocoma, John Paul; Roberts, Victor David

    1998-01-01

    An integrated starting and running amalgam assembly for an electrodeless SEF fluorescent lamp includes a wire mesh amalgam support constructed to jointly optimize positions of a starting amalgam and a running amalgam in the lamp, thereby optimizing mercury vapor pressure in the lamp during both starting and steady-state operation in order to rapidly achieve and maintain high light output. The wire mesh amalgam support is constructed to support the starting amalgam toward one end thereof and the running amalgam toward the other end thereof, and the wire mesh is rolled for friction-fitting within the exhaust tube of the lamp. The positions of the starting and running amalgams on the wire mesh are jointly optimized such that high light output is achieved quickly and maintained, while avoiding any significant reduction in light output between starting and running operation.

  9. [The future of dental amalgam

    NARCIS (Netherlands)

    Opdam, N.J.M.

    2005-01-01

    This paper is a comment on 'The enigma of dental amalgam' by Carl Leinfelder published in 2004 in the Journal of Esthetic and Restorative Dentistry. In that paper a warning is stated against a too abrupt change from amalgam towards resin composite, because this will bring a lot of clinical problems

  10. Amalgams and χ-Boundedness

    DEFF Research Database (Denmark)

    Penev, Irena

    2017-01-01

    , clique-cutsets, and amalgams together preserve χ-boundedness. More precisely, we show that if G and G∗ are hereditary classes of graphs such that G is χ-bounded, and such that every graph in G∗ either belongs to G or admits a proper homogeneous set, a clique-cutset, or an amalgam, then the class G∗ is χ...

  11. [The future of dental amalgam

    NARCIS (Netherlands)

    Opdam, N.J.M.

    2005-01-01

    This paper is a comment on 'The enigma of dental amalgam' by Carl Leinfelder published in 2004 in the Journal of Esthetic and Restorative Dentistry. In that paper a warning is stated against a too abrupt change from amalgam towards resin composite, because this will bring a lot of clinical problems

  12. Dental amalgam - the effect of the technology of alloy powder preparation on the corrosion behaviour and the release of mercury

    Energy Technology Data Exchange (ETDEWEB)

    Joska, L.; Bystriansky, J.; Novak, P. [Institute of Chemical Technology, Prague, Institute of Metals and Corrosion Engineering, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2003-03-01

    Dental amalgams are based on a broad spectrum of materials differing in their chemical composition, metallurgical treatment, and in the way the initial alloys powders are prepared. In addition to their chemical composition, amalgams based on various powders differ in both their microstructure and the amount of mercury needed for preparation. All these facts may affect electrochemical processes occurring during their interaction with oral fluids, and also mercury release. While verifying the effect of the technology used for the preparation of the high-copper ternary alloy powder on the properties of resulting amalgams, this study aimed at the mechanism of their interaction with a model saliva solution as well as mercury release was included. Measurements were done in a model saliva solution using standard electrochemical methods and exposition measurements. The interaction of individual types of amalgams with artificial saliva did not reveal any significant differences. The free corrosion potential of all these amalgams in an aerated solution settled in the range of values in which tin oxidation, resulting in a layer of insoluble corrosion products, turned out to be the dominant anodic process. The rate of mercury release was the lowest for amalgams based on a gas-atomized alloy. The highest rate of mercury release, and also its dependence on time, was exhibited by lathe-cut powder based amalgam. In addition to different volume fraction of the Ag-Hg phase and the level of its tin alloying, this different behaviour may be explained by differences in the rate at which a layer of tin corrosion products acting as a barrier to mercury release is formed. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Dentalamalgame basieren auf einem breitem Spektrum von Werkstoffen, die sich in ihrer chemischen Zusammensetzung, der metallurgischen Behandlung und der Art, wie die Ausgangslegierungspulver hergestellt werden, unterscheiden. Zusaetzlich zu ihrer chemischen

  13. Development of highly faceted reduced graphene oxide-coated copper oxide and copper nanoparticles on a copper foil surface

    Directory of Open Access Journals (Sweden)

    Rebeca Ortega-Amaya

    2016-07-01

    Full Text Available This work describes the formation of reduced graphene oxide-coated copper oxide and copper nanoparticles (rGO-Cu2ONPs, rGO-CuNPs on the surface of a copper foil supporting graphene oxide (GO at annealing temperatures of 200–1000 °C, under an Ar atmosphere. These hybrid nanostructures were developed from bare copper oxide nanoparticles which grew at an annealing temperature of 80 °C under nitrogen flux. The predominant phase as well as the particle size and shape strongly depend on the process temperature. Characterization with transmission electron microscopy and scanning electron microscopy indicates that Cu or Cu2O nanoparticles take rGO sheets from the rGO network to form core–shell Cu–rGO or Cu2O–rGO nanostructures. It is noted that such ones increase in size from 5 to 800 nm as the annealing temperature increases in the 200–1000 °C range. At 1000 °C, Cu nanoparticles develop a highly faceted morphology, displaying arm-like carbon nanorods that originate from different facets of the copper crystal structure.

  14. Development of highly faceted reduced graphene oxide-coated copper oxide and copper nanoparticles on a copper foil surface

    Science.gov (United States)

    Matsumoto, Yasuhiro; Espinoza-Rivas, Andrés M; Pérez-Guzmán, Manuel A; Ortega-López, Mauricio

    2016-01-01

    Summary This work describes the formation of reduced graphene oxide-coated copper oxide and copper nanoparticles (rGO-Cu2ONPs, rGO-CuNPs) on the surface of a copper foil supporting graphene oxide (GO) at annealing temperatures of 200–1000 °C, under an Ar atmosphere. These hybrid nanostructures were developed from bare copper oxide nanoparticles which grew at an annealing temperature of 80 °C under nitrogen flux. The predominant phase as well as the particle size and shape strongly depend on the process temperature. Characterization with transmission electron microscopy and scanning electron microscopy indicates that Cu or Cu2O nanoparticles take rGO sheets from the rGO network to form core–shell Cu–rGO or Cu2O–rGO nanostructures. It is noted that such ones increase in size from 5 to 800 nm as the annealing temperature increases in the 200–1000 °C range. At 1000 °C, Cu nanoparticles develop a highly faceted morphology, displaying arm-like carbon nanorods that originate from different facets of the copper crystal structure. PMID:27547618

  15. Solidification/Stabilization of Elemental Mercury Waste by Amalgamation

    Energy Technology Data Exchange (ETDEWEB)

    Yim, S. P.; Ahn, B. G.; Lee, H. J.; Shon, J. S.; Chung, H.; Kim, K. J.; Lee, C. K.

    2003-02-24

    Experiments on solidification of elemental mercury waste were conducted by amalgamation with several metal powders such as copper, zinc, tin, brass and bronze. Unlike the previous studies which showed a dispersible nature after solidification, the waste forms were found to possess quite large compressive strengths in both copper and bronze amalgam forms. The durability was also confirmed by showing very minor changes of strength after 90 days of water immersion. Leachability from the amalgam forms is also shown to be low: measured mercury concentration in the leachate by the Toxicity Characteristic Leaching Procedure (TCLP) was well below the Environmental Protection Agency (EPA) limit. Long term leaching behavior by Accelerated Leach Test (ALT) has shown that the leaching process was dominated by diffusion and the effective diffusion coefficient was quite low (around 10-19 cm2/sec). The mercury vapor concentration from the amalgam forms were reduced to a 20% level of that for elemental mercury and to one-hundredth after 3 months.

  16. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury, and amalgam alloy. (a) Identification. Dental amalgam is a device that consists of a combination...

  17. Microstructural studies of dental amalgams using analytical transmission electron microscopy

    Science.gov (United States)

    Hooghan, Tejpal Kaur

    Dental amalgams have been used for centuries as major restorative materials for decaying teeth. Amalgams are prepared by mixing alloy particles which contain Ag, Sn, and Cu as the major constituent elements with liquid Hg. The study of microstructure is essential in understanding the setting reactions and improving the properties of amalgams. Until the work reported in this dissertation, optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffractometry (XRD) were used commonly to analyze amalgam microstructures. No previous systematic transmission electron microscopy (TEM) study has been performed due to sample preparation difficulties and composite structure of dental amalgams. The goal of this research was to carry out detailed microstructural and compositional studies of dental amalgams. This was accomplished using the enhanced spatial resolution of the TEM and its associated microanalytical techniques, namely, scanning transmission electron microscopy (STEM), x-ray energy dispersive spectroscopy (XEDS) and micro-microdiffraction (mumuD). A new method was developed for thinning amalgam samples to electron transparency using the "wedge technique." Velvalloy, a low-Cu amalgam, and Tytin, a high-Cu amalgam, were the two amalgams characterized. Velvalloy is composed of a Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) matrix surrounding unreacted Agsb3Sn (gamma) particles. In addition, hitherto uncharacterized reaction layers between Agsb3Sn(gamma)/Agsb2Hgsb3\\ (gammasb2)\\ and\\ Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) were observed and analyzed. An Ag-Hg-Sn (betasb1) phase was clearly identified for the first time. In Tytin, the matrix consists of Agsb2Hgsb3\\ (gammasb1) grains. Fine precipitates of Cusb6Snsb5\\ (etasp') are embedded inside the gammasb1 and at the grain boundaries. These precipitates are responsible for the improved creep resistance of Tytin compared to Velvalloy. The additional Cu has completely eliminated the gammasb

  18. Mercury (Hg) burden in children: the impact of dental amalgam.

    Science.gov (United States)

    Al-Saleh, Iman; Al-Sedairi, Al Anoud

    2011-07-15

    results are alarming and indicate an urgent need for biomonitoring and assessment of exposure. Changes in dental practices involving amalgam, especially for children, are highly recommended in order to avoid unnecessary exposure to Hg.

  19. Do Laboratory Results Concerning High-Viscosity Glass-Ionomers versus Amalgam for Tooth Restorations Indicate Similar Effect Direction and Magnitude than that of Controlled Clinical Trials? - A Meta-Epidemiological Study.

    Directory of Open Access Journals (Sweden)

    Steffen Mickenautsch

    Full Text Available A large percentage of evidence concerning dental interventions is based on laboratory research. The apparent wealth of laboratory evidence is sometimes used as basis for clinical inference and recommendations for daily dental practice. In this study two null-hypotheses are tested: whether trial results from laboratory and controlled clinical trials concerning the comparison of high-viscosity glass-ionomer cements (HVGIC to amalgam for restorations placed in permanent posterior teeth have: (i similar effect direction and (ii similar effect magnitude.7 electronic databases were searched, as well as reference lists. Odds ratios (OR and Standardised Mean Differences (SMD with 95% Confidence intervals were computed for extracted dichotomous and continuous data, respectively. Pooled effect estimates for laboratory and clinical data were computed to test for effect direction. Odds ratios were converted into SMDs. SMDs from laboratory and clinical data were statistically compared to test for differences in effect magnitude. The analysed results were further investigated within the context of potential influencing or confounding factors using a Directed acyclic graph.Of the accepted eight laboratory and nine clinical trials, 13 and 21 datasets could be extracted, respectively. The pooled results of the laboratory datasets were highly statistically significant in favor of amalgam. No statistically significant differences, between HVGICs and amalgam, were identified for clinical data. For effect magnitude, statistically significant differences between clinical and laboratory trial results were found. Both null-hypotheses were rejected.Laboratory results concerning high-viscosity glass-ionomers versus amalgam for tooth restorations do not indicate similar effect direction and magnitude than that of controlled clinical trials.

  20. Electrochemical study of insulating properties of dental amalgam bonding polymers.

    Science.gov (United States)

    Toumelin-Chemla, F; Degrange, M

    1998-06-01

    The standard techniques used for amalgam restorations often result in a lack of adhesion to mineralized dental tissues. The bonding of amalgam with polymer has been suggested to improve its adaptation to dental tissues. Moreover the polymer involved in the bonding should inhibit the corrosion and the diffusion of metallic ions. The aim of this study was to evaluate in vitro the capacity of bonded amalgam to prevent ionic diffusion and migration. In this respect, an original method employing electrochemical techniques was used to determine the leakage current of bonded amalgam restorations. The electrochemical behaviour of conventional and bonded amalgam restorations was compared using a potentiostat driven by a computerized system (Voltamaster, Radiometer Analytical) with software for specific applications such as chronoamperometry or cyclic voltammetry. Samples of recently extracted teeth of young patients were first examined, and then the results were checked by other experimental assays using protected and unprotected copper sticks. The measurements obtained with chronoamperometry (E = +300 mV/SCE) in Ringer's solution at 37 degrees C showed that after polarization for 30 h the oxidation current decreased threefold for bonded samples (10 microA cm(-2)) as compared with the unprotected samples (35 microA cm(-2)). These results, as well as those obtained with the copper wires, demonstrated that even with two layers of adhesive the bonded joint is permeable to ions probably as a result of the hydrophylic properties of HEMA, a component of the adhesive. However, using five layers of adhesive reduced the ionic current by a factor as large as 10(6).

  1. Electrochemical study of insulating properties of dental amalgam bonding polymers

    Energy Technology Data Exchange (ETDEWEB)

    Toumelin-Chemla, Florence; Degrange, Michel [Faculte de Chirurgie Dentaire de Paris V, Montrouge (France)

    1998-06-01

    The standard techniques used for amalgam restorations often result in a lack of adhesion to mineralized dental tissues. The bonding of amalgam with polymer has been suggested to improve its adaptation to dental tissues. Moreover the polymer involved in the bonding should inhibit the corrosion and the diffusion of metallic ions. The aim of this study was to evaluate in vitro the capacity of bonded amalgam to prevent ionic diffusion and migration. In this respect, an original method employing electrochemical techniques was used to determine the leakage current of bonded amalgam restorations. The electrochemical behaviour of conventional and bonded amalgam restorations was compared using a potentiostat driven by a computerized system (Voltamaster, Radiometer Analytical) with software for specific applications such as chronoamperometry or cyclic voltammetry. Samples of recently extracted teeth of young patients were first examined, and then the results were checked by other experimental assays using protected and unprotected copper sticks. The measurements obtained with chronoamperometry (E=+300 mV/SCE) in Ringer's solution at 37 deg. C showed that after polarization for 30 h the oxidation current decreased threefold for bonded samples (10 {mu}A cm{sup -2}) as compared with the unprotected samples (35 {mu}A cm{sup -2}). These results, as well as those obtained with the copper wires, demonstrated that even with two layers of adhesive the bonded joint is permeable to ions probably as a result of the hydrophylic properties of HEMA, a component of the adhesive. However, using five layers of adhesive reduced the ionic current by a factor as large as 10{sup 6}. (author)

  2. Mercury (Hg) burden in children: The impact of dental amalgam

    Energy Technology Data Exchange (ETDEWEB)

    Al-Saleh, Iman, E-mail: iman@kfshrc.edu.sa [Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, PO Box: 3354, Riyadh 11211 (Saudi Arabia); Al-Sedairi, Al anoud [Department of Zoology, College of Science, King Saud University, PO Box: 24452, Riyadh 11495 (Saudi Arabia)

    2011-07-15

    /or nephrotoxic effects of such an increased Hg on children should be a cause of concern, and further investigation is warranted. Our results are alarming and indicate an urgent need for biomonitoring and assessment of exposure. Changes in dental practices involving amalgam, especially for children, are highly recommended in order to avoid unnecessary exposure to Hg. - Research Highlights: {yields} The extent of Hg exposure in children 5-15 years of age with and without dental amalgam fillings was examined. {yields} Hg was measured in urine, hair and toenails to assess their sensitivity, specificity, and reliability as biomarkers of Hg exposure. {yields} The levels of UHg-C and HHg were significantly higher in children with dental amalgam compared to those without. {yields} The reliability of nails to determine associations with dental amalgam fillings may be limited, especially if the levels of Hg in nails are low. {yields} This study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health.

  3. Role of the human high-affinity copper transporter in copper homeostasis regulation and cisplatin sensitivity in cancer chemotherapy.

    Science.gov (United States)

    Kuo, Macus Tien; Fu, Siqing; Savaraj, Niramol; Chen, Helen H W

    2012-09-15

    The high-affinity copper transporter (Ctr1; SCLC31A1) plays an important role in regulating copper homeostasis because copper is an essential micronutrient and copper deficiency is detrimental to many important cellular functions, but excess copper is toxic. Recent research has revealed that human copper homeostasis is tightly controlled by interregulatory circuitry involving copper, Sp1, and human (hCtr1). This circuitry uses Sp1 transcription factor as a copper sensor in modulating hCtr1 expression, which in turn controls cellular copper and Sp1 levels in a 3-way mutual regulatory loop. Posttranslational regulation of hCtr1 expression by copper stresses has also been described in the literature. Because hCtr1 can also transport platinum drugs, this finding underscores the important role of hCtr1 in platinum-drug sensitivity in cancer chemotherapy. Consistent with this notion is the finding that elevated hCtr1 expression was associated with favorable treatment outcomes in cisplatin-based cancer chemotherapy. Moreover, cultured cell studies showed that elevated hCtr1 expression can be induced by depleting cellular copper levels, resulting in enhanced cisplatin uptake and its cell-killing activity. A phase I clinical trial using a combination of trientine (a copper chelator) and carboplatin has been carried out with encouraging results. This review discusses new insights into the role of hCtr1 in regulating copper homeostasis and explains how modulating cellular copper availability could influence treatment efficacy in platinum-based cancer chemotherapy through hCtr1 regulation.

  4. Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS.

    Science.gov (United States)

    Bello, Liciane Toledo; da Ana, Patricia Aparecida; Santos, Dário; Krug, Francisco José; Zezell, Denise Maria; Vieira, Nilson Dias; Samad, Ricardo Elgul

    2017-01-01

    In this work the diffusion of mercury and other elements from amalgam tooth restorations through the surrounding dental tissue (dentin) was evaluated using femtosecond laser-induced breakdown spectroscopy (fs-LIBS). To achieve this, seven deciduous and eight permanent extracted human molar teeth with occlusal amalgam restorations were half-sectioned and analyzed using pulses from a femtosecond laser. The measurements were performed from the amalgam restoration along the amalgam/dentin interface to the apical direction. It was possible to observe the presence of metallic elements (silver, mercury, copper and tin) emission lines, as well as dental constituent ones, providing fingerprints of each material and comparable data for checking the consistence of the results. It was also shown that the elements penetration depth values in each tooth are usually similar and consistent, for both deciduous and permanent teeth, indicating that all the metals diffuse into the dentin by the same mechanism. We propose that this diffusion mechanism is mainly through liquid dragging inside the dentin tubules. The mercury diffused further in permanent teeth than in deciduous teeth, probably due to the longer diffusion times due to the age of the restorations. It was possible to conclude that the proposed femtosecond-LIBS system can detect the presence of metals in the dental tissue, among the tooth constituent elements, and map the distribution of endogenous and exogenous chemical elements, with a spatial resolution that can be brought under 100 µm.

  5. Trace Operators on Wiener Amalgam Spaces

    OpenAIRE

    Jayson Cunanan; Yohei Tsutsui

    2016-01-01

    The paper deals with trace operators of Wiener amalgam spaces using frequency-uniform decomposition operators and maximal inequalities, obtaining sharp results. Additionally, we provide the embeddings between standard and anisotropic Wiener amalgam spaces.

  6. The comparative evaluation of fracture resistance and microleakage in bonded amalgam, amalgam, and composite resins in primary molars

    Directory of Open Access Journals (Sweden)

    H S Vanishree

    2015-01-01

    Conclusions: Bonded amalgam appears to be comparable to amalgam when microleakage is considered and to composite resin when fracture resistance is considered; hence, bonded amalgam can also be an alternative material to amalgam in primary molars.

  7. Shandong Hengyuan 200,000 tonnes of High-Precision Copper Product Project is Making Smooth Progress

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Shandong Hengyuan Copper Co., Ltd is an emerging copper product processing enterprise in China, the company plans to invest 1 billion yuan to construct 200,000 t/a high precision copper product, which includes: 20,000 tones of precision copper tube and copper alloy tube, 10,000 tonnes of railway electrification copper

  8. Copper Deficiency in Sheep with High Liver Iron Accumulation

    Directory of Open Access Journals (Sweden)

    Isadora Karolina Freitas de Sousa

    2012-01-01

    Full Text Available An outbreak of enzootic ataxia among sheep raised in the northeastern region of Brazil is described. Copper (Cu deficiency was diagnosed in a herd of 56 sheep, among which five presented characteristic clinical symptoms of enzootic ataxia. The symptoms began 30 days after birth, with a clinical condition that included locomotion difficulty, limb ataxia, tremors, and continual falls. Liver biopsies were performed and blood was collected to determine hepatic and plasmatic Cu, iron (Fe, and zinc (Zn concentration, respectively. The laboratory results showed that the animals presented low copper concentrations in the plasma and liver, without difference between the clinically healthy animals and those affected by enzootic ataxia. Even after supplementation with adequate Cu levels had been recommended, it was found on a new visit to the farm four months later that one animal still presented a clinical condition and that the hepatic Cu levels of the herd had not risen. Despite the low copper content of the diet, the high hepatic Fe levels found suggest that antagonism due to this element may have been an important factor in triggering copper deficiency in these animals, and thus, additional copper supplementation may be necessary for these animals.

  9. Copper oxide as a high temperature battery cathode material

    Science.gov (United States)

    Ritchie, A. G.; Mullins, A. P.

    1994-10-01

    Copper oxide has been tested as a cathode material for high temperature primary reserve thermal batteries in single cells at 530 to 600 C and at current densities of 0.1 to 0.25 A cm(exp -2) using lithium-aluminium alloy anodes and lithium fluoride-lithium chloride-lithium bromide molten salt electrolytes. Initial on-load voltages were around 2.3 V, falling to 1.5 V after about 0.5 F mol(exp -1) had been withdrawn. Lithium copper oxide, LiCu2O2, and cuprous oxide, Cu2O, were identified as discharge products.

  10. Comprehension of amalgamation for future digital society

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byeong Uk

    2010-08-15

    This book deals with understanding of amalgamation for future digital society, which describes outline of amalgamation, ubiquitous environment, cognitive science I such as psychology and neurology, cognitive science II like philosophy, linguistics and anthropology, an automatic machine, evolution theory and amalgamation, brain science and consciousness, mind and software and creativity and art. Each chapter has introduction, composition, related science, function and models.

  11. Penetration of amalgam constituents into dentine

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; Ozcan, Mutlu; Huysmans, Marie-Charlotte D. N. J. M.

    2009-01-01

    Objectives: Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. it is questioned whet

  12. Penetration of amalgam constituents into dentine.

    NARCIS (Netherlands)

    Scholtanus, J.D.; Ozcan, M.; Huysmans, M.C.D.N.J.M.

    2009-01-01

    OBJECTIVES: Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. It is questioned whet

  13. High-grade metamorphism during Archean-Paleoproterozoic transition associated with microblock amalgamation in the North China Craton: Mineral phase equilibria and zircon geochronology

    Science.gov (United States)

    Yang, Qiong-Yan; Santosh, M.; Tsunogae, Toshiaki

    2016-10-01

    Metamorphic regimes in Archean terranes provide important keys to the plate tectonic processes in early Earth. The North China Craton (NCC) is one of the ancient continental nuclei in Asia and recent models propose that the cratonic architecture was built through the assembly of several Archean microcontinental blocks into larger crustal blocks. Here we investigate garnet- and pyroxene-bearing granulite facies rocks along the periphery of the Jiaoliao microcontinental block in the NCC. The garnet-bearing granulites contain peak mineral assemblage of garnet + clinopyroxene + orthopyroxene + magnetite + plagioclase + quartz ± biotite ± ilmenite. Mineral phase equilibria computations using pseudosection and geothermobarometry suggest peak P-T condition of 800-830 °C and 7-8 kbar for metamorphism. Isopleths using XMg of orthopyroxene and XCa of garnet in another sample containing the peak mineral assemblage of garnet + orthopyroxene + quartz + magnetite ± fluid yield peak P-T conditions of 860-920 °C and 11-14 kbar. Geochemical data show tonalitic to granodioritic composition and arc-related tectonic setting for the magmatic protoliths of these rocks. Zircon LA-ICP-MS analyses yield well-defined discordia with upper intercept ages of 2562 ± 20 Ma (MSWD = 0.94) and 2539 ± 21 Ma (MSWD = 0.59) which is correlated with the timing of emplacement of the magmatic protolith. A younger group of zircons with upper intercept ages of 2449 ± 41 Ma (MSWD = 0.83); N = 6 as 2449 ± 41 Ma (MSWD = 0.83; N = 6) and 2480 ± 44 Ma (MSWD = 1.2; N = 9) constrains the timing of metamorphism. Zircon Lu-Hf data show dominantly positive εHf(t) values (up to 8.5), and yield crustal residence ages (TDMC) in the range of 2529 to 2884 Ma, suggesting magma sources from Meso-Neoarchean juvenile components. The high temperature and medium to high pressure metamorphism is considered to have resulted from the subduction-collision tectonics associated with microblock amalgamation in the NCC at

  14. Optimizing the procedure for mercury recovery from dental amalgam

    Directory of Open Access Journals (Sweden)

    Flávia Godoy Iano

    2008-06-01

    Full Text Available Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%, silver (30% and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650°C, long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90% from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.

  15. A Safe Protocol for Amalgam Removal

    Directory of Open Access Journals (Sweden)

    Dana G. Colson

    2012-01-01

    Full Text Available Today's environment has different impacts on our body than previous generations. Heavy metals are a growing concern in medicine. Doctors and individuals request the removal of their amalgam (silver mercury restorations due to the high mercury content. A safe protocol to replace the silver mercury filling will ensure that there is minimal if any absorption of materials while being removed. Strong alternative white composite and lab-processed materials are available today to create a healthy and functioning mouth. Preparation of the patient prior to the procedure and after treatment is vital to establish the excretion of the mercury from the body.

  16. Dental amalgam: few proven harmful effects but many ongoing concerns.

    Science.gov (United States)

    2008-12-01

    (1) Dental amalgam is one of the main sources of exposure to mercury in industrialised countries; (2) At high doses, mercury is both neurotoxic and nephrotoxic. A suspected link exists between chronic exposure to low doses of mercury derived from dental amalgam and renal, neurodegenerative or neurobehavioural disorders, but it has not been established; (3) Some individual cases are troubling, but epidemiological studies show no major effects in the general population. Various hypotheses have been proposed to explain why some people may be more sensitive than others to the effects of low-dose mercury; (4) More and more countries, especially Sweden, recommend that the use of amalgam should be restricted, particularly in pregnant women and children; (5) As part of a global strategy to eliminate mercury, the European Parliament has asked the Commission to draft legislation limiting the use of mercury in dental amalgam; (6) Evaluation of the risk-benefit balances of alternatives to dental amalgam does not provide sufficient data on which to base an informed choice between available options.

  17. Microleakage in primary teeth restored by conventional or bonded amalgam technique.

    Science.gov (United States)

    Myaki, S I; Rodrigues, C R; Raggio, D P; Flores, T A; Matson, M R

    2001-01-01

    The aim of this in vitro study was to evaluate marginal leakage in class V restorations in primary teeth restored with amalgam, using three different techniques. Thirty maxillary anterior primary teeth, clinically sound and naturally exfoliated, were used. In group 1 (n = 10), two thin layers of a copal varnish (Cavitine) were applied. In group 2 (n = 10), Scotchbond Multi-Purpose Plus, a dual adhesive system, was used according to manufacturer instructions. In group 3 (n = 10), One-Step adhesive system in combination with a low-viscosity resin (Resinomer) were used according to manufacturer instructions. All samples were restored with a high-copper dental amalgam alloy (GS 80, SDI). After restoration, the samples were stored in normal saline at 37 degrees C for 72 h. The specimens were polished, thermocycled (500 cycles, 5 degrees and 55 degrees C, 30-s dwell time) and impermeabilized with fingernail polish to within 1.0 mm of the restoration margins. The teeth were then placed in 0.5% methylene blue for 4 h. Finally, the samples were sectioned and evaluated for marginal leakage. The Kruskal-Wallis test showed that the filled adhesive resin (group 3) had the least microleakage. There was no significant difference between groups 1 and 2.

  18. Deformation behavior of dispersion-strengthened copper at high temperature

    Institute of Scientific and Technical Information of China (English)

    WANG Mengjun; ZHANG Yingchun; LUO Yun; LIU Xinyu

    2006-01-01

    The deformation behavior of dispersion-strengthened copper with different compositions was investigated by hot compression simulation tests on a Gleeble-1500 thermal-mechanical simulator. The microstructure during deformation at high temperature was also studied. The result shows that at the beginning of hot compression simulation, the flowing stress of the dispersion-strengthened copper quickly attains a peak value and the stress shows a greater decrease when the temperature is higher and the strain rate is lower. The dispersion particles lead to an obvious increase in the recrystallization temperature. Under experimental conditions, dynamic recovery is the main softening method. The constitutive equation at high temperature of 1.2%Al2O3-0.4%WC/Cu is obtained.

  19. Bond strength of repaired amalgam restorations.

    Science.gov (United States)

    Rey, Rosalia; Mondragon, Eduardo; Shen, Chiayi

    2015-01-01

    This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam. Repaired specimens were stored in artificial saliva for 1, 10, 30, 120, or 360 days before being loaded to failure in a 3-point bending test. Statistical analysis showed significant changes in median FS over time in groups 2 and 4. The effect of the repair method on the FS values after each storage period was significant for most groups except the 30-day storage groups. Amalgam-amalgam repair with adequate condensation yielded the most consistent and durable bond. An amalgam bonding agent could be beneficial when firm condensation on the repair surface cannot be achieved or when tooth structure is involved. Composite resin can be a viable option for amalgam repair in an esthetically demanding region, but proper mechanical modification of the amalgam surface and selection of the proper bonding system are essential.

  20. Twinning in copper deformed at high strain rates

    Indian Academy of Sciences (India)

    S Cronje; R E Kroon; W D Roos; J H Neethling

    2013-02-01

    Copper samples having varying microstructures were deformed at high strain rates using a split-Hopkinson pressure bar. Transmission electron microscopy results show deformation twins present in samples that were both annealed and strained, whereas samples that were annealed and left unstrained, as well as samples that were unannealed and strained, are devoid of these twins. These deformation twins occurred at deformation conditions less extreme than previously predicted.

  1. Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    John G. Cowie; Edwin F. Brush, Jr.; Dale T. Peters; Stephen P. Midson; Darryl J. Van Son

    2003-05-01

    The objective of the study, Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency, was to support the Copper Development Association (CDA) in its effort to design, fabricate and demonstrate mold technologies designed to withstand the copper motor rotor die casting environment for an economically acceptable life. The anticipated result from the compiled data and tests were to: (1) identify materials suitable for die casting copper, (2) fabricate motor rotor molds and (3) supply copper rotor motors for testing in actual compressor systems. Compressor manufacturers can apply the results to assess the technical and economical viability of copper rotor motors.

  2. Copper metabolism in analbuminaemic rats fed a high-copper diet.

    NARCIS (Netherlands)

    Yu, S.; Berg, van den G.J.; Beynen, A.C.

    1995-01-01

    Copper metabolism in male Nagase analbuminaemic (NA) rats was compared with that in male Sprague Dawley (SD) rats fed purified diets containing either 5 or 100 mg Cu/kg diet. Dietary copper loading increased hepatic and kidney copper concentrations in both strains to the same extent, but baseline va

  3. Amalgam tattoo mimicking mucosal melanoma: a diagnostic dilemma revisited.

    Science.gov (United States)

    Lundin, K; Schmidt, G; Bonde, C

    2013-01-01

    Mucosal melanoma of the oral cavity is a rare but highly aggressive neoplasm. However, the clinicians need to be aware of the other and more frequent etiologies of intraoral pigmentation, such as amalgam tattoos. As amalgam has been extensively used for dental restorations and can cause pigmentations in the oral mucosa, this is a differential diagnosis not to be forgotten. We describe the characteristics of these two phenomena and present a case vignette illustrating the differential diagnostic issues. Other causes of intraoral pigmentation are summarized.

  4. High temperature fatigue behavior of tungsten copper composites

    Science.gov (United States)

    Verrilli, M. J.; Kim, Y.-S.; Gabb, T. P.

    1990-01-01

    The present study investigates the high-temperature fatigue behavior of a 9-v/o tungsten fiber-reinforced copper matrix composite. Load-controlled isothermal fatigue at 260 and 560 C and thermomechanical fatigue (TMF) experiments, both in-phase and out-of-phase between 260 and 560 C, were performed. The stress-strain response under all conditions displayed considerable inelasticity. Strain ratchetting was observed during all the fatigue experiments. For the isothermal fatigue and in-phase TMF tests, the ratchetting was always in a tensile direction, continuing until failure. The ratchetting during the out-of-phase TMF test shifted from a tensile to a compressive direction. For all cases, the fatigue lives were found to be controlled by the damage of the copper matrix. On a stress basis, TMF loading substantially reduced lives relative to isothermal cycling.

  5. Determination of light elements in amalgam restorations. [Dental amalgam

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Osborne, J.W.; Nelson, G.V.

    1982-01-01

    Rutherford backscattering has been used to measure the major elemental compositions in the near-surface regions of freshly prepared and used samples of dental amalgam. A depletion from bulk stoichiometry of the major elements, which indicates an accumulation of lighter elements on the surface of the materials, has been observed. Increases in the F, Na, Cl, P, O, C, and N concentrations between freshly prepared samples and used samples were measured by observation of gamma rays produced by proton and deuteron induced reactions.

  6. Critical appraisal: dental amalgam update--part II: biological effects.

    Science.gov (United States)

    Wahl, Michael J; Swift, Edward J

    2013-12-01

    Dental amalgam restorations have been controversial for over 150 years. In Part I of this Critical Appraisal, the clinical efficacy of dental amalgam was updated. Here in Part II, the biological effects of dental amalgam are addressed.

  7. Process Optimization for Valuable Metal Recovery from Dental Amalgam Residues

    Directory of Open Access Journals (Sweden)

    C.M. Parra–Mesa

    2009-07-01

    Full Text Available In this paper, the methodology used for optimizing leaching in a semi pilot plant is presented. This leaching process was applied to recover value metals from dental amalgam residues. 23 factorial design was used to characterize the process during the first stage and in the second one, a central compound rotational design was used for modeling copper percentage dissolved, a function of the nitric acid concentration, leaching time and temperature. This model explained the 81% of the response variability, which is considered satisfactory given the complexity of the process kinetics and, furthermore, it allowed the definition of the operation conditions for better copper recovery, which this was of 99.15%, at a temperature of 55°C, a concentration of 30% by weight and a time of 26 hours.

  8. Fatigue behavior of copper and selected copper alloys for high heat flux applications

    Energy Technology Data Exchange (ETDEWEB)

    Leedy, K.D.; Stubbins, J.F.; Singh, B.N.; Garner, F.A.

    1996-04-01

    The room temperature fatigue behavior of standard and subsize specimens was examined for five copper alloys: OFHC Cu, two CuNiBe alloys, a CuCrZr alloy, and a Cu-Al{sub 2}O{sub 3} alloy. Fatigue tests were run in strain control to failure. In addition to establishing failure lives, the stress amplitudes were monitored as a function of numbers of accrued cycles. The results indicate that the alloys with high initial yield strengths provide the best fatigue response over the range of failure lives examined in the present study: N{sub f} = 10{sup 3} to 10{sup 6}. In fact, the fatigue performance of the best alloys is dominated by the elastic portion of the strain range, as would be expected from the correlation of performance with yield properties. The alumina strengthened alloy and the two CuNiBe alloys show the best overall performance of the group examined here.

  9. Microstrain in Nanocrystalline Copper by High Resolution Electron Microscopy

    Institute of Scientific and Technical Information of China (English)

    MIN Changping; RUAN Xuefeng; ZOU Huamin

    2009-01-01

    The elastic microstrains in a crystallite of electrodeposited nanocrystalline copper were investigated by analyzing the high resolution electron microscopy(HRTEM)image.The mi-crostrain was considered as consisting of two parts,in which the uniform part was determined with fast Fourier transformation of the HRTEM image,while the non-uniform part of the microstrain in the crystallite was measured by means of peak finding.Atomic column spacing measurements show that the crystal lattice is contracted in the longitudinal direction,while expanded in the transverse direction of the elliptical crystallite,indicating that the variation of microstrain exists mainly near the grain boundary.

  10. Fourier transforms on an amalgam type space

    CERN Document Server

    Liflyand, E

    2012-01-01

    We introduce an amalgam type space, a subspace of $L^1(\\mathbb R_+).$ Integrability results for the Fourier transform of a function with the derivative from such an amalgam space are proved. As an application we obtain estimates for the integrability of trigonometric series.

  11. Elimination of mercury from amalgam in rats

    Energy Technology Data Exchange (ETDEWEB)

    Galic, N. [Dept. of Dental Pathology, School of Dentistry, Zagreb (Croatia); Prpic-Mehicic, G.; Prester, Lj.; Blanusa, M. [Inst. for Medical Research and Occupational Health, Zagreb (Croatia); Krnic, Z.; Erceg, D. [Pliva Pharmaceutical Co., Biomedicine Research Inst. ' ' Pliva' ' , Zagreb (Croatia)

    2001-07-01

    The aim of this study was to measure the urinary mercury excretion in rats exposed to amalgam over a two months period. Animals were either exposed to mercury from 4 dental amalgams or fed the diet containing powdered amalgams. The results showed significantly higher mercury amount in urine of both exposed groups than in control. Even two months after the amalgam had been placed in rats teeth, the amount of mercury in the urine remained 4-5 times higher than in control, and 4 times higher than in rats exposed to diet containing powdered amalgam. The elevated urinary Hg amount was accompanied by an increased level of total protein in urine. In the same exposure period the excretion of total protein in urine of rats with amalgam fillings was 2 times higher than in control and 1.5 times higher than in rats exposed to amalgam through diet. Concentrations of mercury in the sera of all groups were below the detection limit of the method. The results show that amount of mercury and protein in the urine of rats were related to the mercury release from dental amalgam. (orig.)

  12. Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments.

    Science.gov (United States)

    Tsujino, J; Ihara, S; Harada, Y; Kasahara, K; Sakamaki, N

    2004-04-01

    Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration.

  13. Dental Amalgam Exposure and Urinary Mercury Levels in Children: The New England Children’s Amalgam Trial

    OpenAIRE

    Maserejian, Nancy Nairi; Trachtenberg, Felicia L.; Assmann, Susan F.; Barregard, Lars

    2007-01-01

    Background Urinary mercury (U-Hg) excretion is a commonly used biomarker for mercury exposure from dental amalgam restorations. Objectives Our goal was to determine the most efficient measure of dental amalgam exposure for use in analyses concerning U-Hg in children. Methods We analyzed time-sensitive longitudinal amalgam exposure data in children randomized to amalgam restorations (n = 267) during the 5-year New England Children’s Amalgam Trial. We calculated 8 measures of amalgam, evaluatin...

  14. Flash light sintered copper precursor/nanoparticle pattern with high electrical conductivity and low porosity for printed electronics

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Wan-Ho; Hwang, Hyun-Jun [Department of Mechanical Convergence Engineering, Hanyang University, 17 Haendang-Dong, Seongdong-Gu, Seoul 133-791 (Korea, Republic of); Kim, Hak-Sung, E-mail: kima@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, 17 Haendang-Dong, Seongdong-Gu, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-04-01

    In this work, the hybrid copper inks with precursor and nanoparticles were fabricated and sintered via flash light irradiation to achieve highly conductive electrode pattern with low porosity. The hybrid copper ink was made of copper nanoparticles and various copper precursors (e.g., copper(II) chloride, copper(II) nitrate trihydrate, copper(II) sulfate pentahydrate and copper(II) trifluoroacetylacetonate). The printed hybrid copper inks were sintered at room temperature and under ambient conditions using an in-house flash light sintering system. The effects of copper precursor weight fraction and the flash light irradiation conditions (light energy and pulse duration) were investigated. Surfaces of the sintered hybrid copper patterns were analyzed using a scanning electron microscope. Also, spectroscopic characterization techniques such as Fourier transform infrared spectroscopy and X-ray diffraction were used to investigate the crystal phases of the flash light sintered copper precursors. High conductivity hybrid copper patterns (27.3 μΩ cm), which is comparable to the resistivity of bulk copper (1.68 μΩ cm) were obtained through flash light sintering at room temperature and under ambient conditions. - Highlights: • The hybrid copper inks with precursor and nanoparticles were fabricated. • The hybrid copper ink was sintered via flash light irradiation. • The resistivity of sintered hybrid copper ink was 27.3 μΩ cm. • Highly conductive copper film with low porosity could be achieved.

  15. Dense superconducting phases of copper-bismuth at high pressure

    Science.gov (United States)

    Amsler, Maximilian; Wolverton, Chris

    2017-08-01

    Although copper and bismuth do not form any compounds at ambient conditions, two intermetallics, CuBi and Cu11Bi7 , were recently synthesized at high pressures. Here we report on the discovery of additional copper-bismuth phases at elevated pressures with high densities from ab initio calculations. In particular, a Cu2Bi compound is found to be thermodynamically stable at pressures above 59 GPa, crystallizing in the cubic Laves structure. In strong contrast to Cu11Bi7 and CuBi, cubic Cu2Bi does not exhibit any voids or channels. Since the bismuth lone pairs in cubic Cu2Bi are stereochemically inactive, the constituent elements can be closely packed and a high density of 10.52 g/cm3 at 0 GPa is achieved. The moderate electron-phonon coupling of λ =0.68 leads to a superconducting temperature of 2 K, which exceeds the values observed both in Cu11Bi7 and CuBi, as well as in elemental Cu and Bi.

  16. Silicon-embedded copper nanostructure network for high energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Tianyue

    2016-03-15

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  17. Metallothionein in human gingival amalgam tattoos.

    Science.gov (United States)

    Lau, J C; Jackson-Boeters, L; Daley, T D; Wysocki, G P; Cherian, M G

    2001-11-01

    Amalgam tattoos occur when small particles of dental amalgam, composed largely of silver (Ag) and mercury (Hg), are inadvertently implanted into oral soft tissues during dental procedures. Metallothioneins (MTs) are ubiquitous, low molecular weight, cysteine-rich, metal-binding proteins that are inducible by many agents including metals and may be involved in the detoxification of toxic metals such as Hg. In this study, the correlation between MT expression and amalgam tattoos in human gingiva was investigated using energy-dispersive X-ray microanalysis (EDX) and immunohistochemical techniques. Light microscopically, amalgam tattoos presented as either fine granular particles or larger discrete opaque globular particles in connective tissues. EDX revealed the smaller particles to be silver sulphide (Ag(2)S), while the larger particles exhibited a shell of Ag(2)S that contained irregularly distributed masses of Ag and Hg. Particles of tin (Sn) were also found. No MT staining was observed in collagen, fibroblasts or blood vessels in areas exhibiting abundant amounts of embedded fine granular Ag(2)S particles. Blood vessels exhibiting relatively few amalgam particles stained positively for MT. Cells with the morphological features of histiocytes located directly adjacent to larger pieces of amalgam showed intense MT staining. These results indicate that amalgam tattoos contain no Hg or free Ag except in large globular pieces of amalgam, which still contain Hg and which induce MT expression in adjacent histiocytes. This suggests that Hg leaching from impacted dental amalgam particles induces MT, while residual Ag(2)S and Sn particles do not. MT may therefore act to reduce Hg exposure in patients with amalgam tattoos.

  18. Spectral and gravimetric analysis of completely oxidized amalgam systems.

    Science.gov (United States)

    Mueller, H J

    1980-01-01

    Analysis of the soluble solution species, insoluble solution precipitate, adherent corrosion products, and microstructural changes of the substrate amalgam after selected polarization to -0.2v and +0.5v in a chloride solution is reported. Results indicate only small concentrations of soluble species, high concentrations of a Sn insoluble solution precipitate at -0.2v, and high concentrations of a Cu precipitate at +0.5v, related to CuCl2 . 3 Cu (OH)2. The completely oxidized amalgam microstructure indicates a thin outermost layer of predominantly Sn--Cl, a thick corroded layer of Ag-Sn-Hg-Cl, and the remaining substrate amalgam. The compound of (SnO) 160 is also associated with the thick corroded layer. The microstructure of the substrate amalgam exhibits, besides the normally occurring phases and products, four new phases or alterations due to the redistribution of Sn, Cl and 0 from the gamma-2 corrosion products, (1) the reappearance of voids, (2) a grey Ag-Sn-Cl phase with and without Cu localized at specific sites in the gamma-1 matrix, (3) dark areas or partially filled voids containing the same elements as in (2) and formerly occupied by the gamma-2 products, and (4) a Cu-rich phase from the deterioration of the Cu6Sn5 phase and also included within the matrix. These changes, particularly (1), (2) and (3) occur with the onset of the gamma-1 deterioration. Unreacted Ag3Sn including the additions of the Cu3Sn component is the last phase to be attacked in the composite amalgam.

  19. The use of amalgam in pediatric dentistry: new insights and reappraising the tradition.

    Science.gov (United States)

    Fuks, Anna B

    2015-01-01

    The debate on amalgam led to its being phased out in some countries. Results of clinical trials report failure rates of amalgams ranging from 12 percent to over 70 percent. Treatment of caries should meet the needs of each particular patient, based on his/her caries risk. In general, for small occlusal lesions, a conservative preventive resin restoration would be more appropriate than the classic Class I amalgam preparation. For proximal lesions, amalgam would be indicated for two-surface Class II preparations that do not extend beyond the line angles of primary teeth. This recommendation might not be appropriate for high-risk patients or restoring primary first molars in children four years old and younger where stainless steel crowns have demonstrated better longevity. Currently, amalgam demonstrates the best clinical success for Class II restorations that extend beyond the proximal line angles of permanent molars. The need to reduce the use of amalgam as a mercury-containing material is inevitable when aiming to reduce environmental contamination. It is important always to praise prevention and constantly search for biologically safe materials regarding health, clinical work, and environment. The purpose of this report was to summarize several factors that affect the effectiveness, advantages, and disadvantages of using dental amalgam in primary teeth.

  20. [Dental amalgams and mercury polemic in Abidjan].

    Science.gov (United States)

    Avoaka-Boni, M-C; Adou-Assoumou, N M; Sinan, A A; Abouattier-Mansilla, E C

    2007-12-01

    Dental amalgam is metallic biomaterials which has raised a number of controversies in the past few years, because of mercury potential toxicity. Considering the significance of theses controversies, this study was carried out with a view to evaluating the behaviour of Abidjan-based practitioners with respect to dental amalgam. The contemplated objective is to determine the frequency in the use of dental amalgam, to identify the problems encountered using dental amalgam and to propose solutions for fighting mercury contamination. The results show that dental amalgam is used in 81.8% for posterior teeth restoration. The side effects mentioned are metallic taste, gingival tattoo, galvanic corrosion and tooth pain. This is why 21.8 % of practitioners believe that the controversy over dental amalgam has merits while 45.5% hold the contrary opinion because of lack of scientific arguments. However, considering the absence of means to treat amalgam waste, dentist practitioners and authorities have to get involved to fight against mercury contamination.

  1. Mercury release during autoclave sterilization of amalgam.

    Science.gov (United States)

    Parsell, D E; Karns, L; Buchanan, W T; Johnson, R B

    1996-05-01

    Natural teeth are an invaluable teaching tool for preclinical instruction in operative dentistry and endodontic techniques. Cavity preparation in teeth containing amalgam restorations is a realistic simulation of an often experienced clinical situation. As various pathogens are contained in saliva, teeth must be disinfected before use by students. The purpose of this study is to indirectly evaluate whether mercury vapor is released from amalgam restorations in such teeth during steam autoclave sterilization. Mercury vapor detection, sample mass changes and x-ray fluorescence data were collected from experimental steam autoclave sterilization of amalgam samples sealed in autoclave bags. All of the data showed evidence of mercury vapor generation coincident to steam autoclave sterilization. Mercury vapor levels within the room where amalgam was exposed to steam autoclave sterilization reached levels that constitute an unnecessary health risk to dental personnel. The volume of amalgam tested simulated that contained in 175 amalgam restored teeth. Initial venting of the autoclave chamber produced mercury vapor concentrations significantly in excess of OSHA vapor concentration ceiling levels. Thus, the use of a steam autoclave for sterilization of amalgam containing teeth for use in preclinical laboratory exercises may be harmful to personnel involved.

  2. Extensive amalgam tattoo on the alveolar-gingival mucosa.

    Science.gov (United States)

    Galletta, Vivian C; Artico, Gabriela; Dal Vechio, Aluana M C; Lemos Jr, Celso A; Migliari, Dante A

    2011-01-01

    Amalgam tattoos are common exogenous pigmented lesions of the oral mucosa occurring mainly by inadvertent placement of amalgam particles into soft tissues. The diagnosis of amalgam tattoo is simple, usually based on clinical findings associated with presence or history of amalgam fillings removal. Intraoral X-rays may be helpful in detecting amalgam-related radiopacity. In cases where amalgam tattoo cannot be differentiated from other causes of oral pigmentation, a biopsy should be performed. This article deals with an extensive amalgam tattoo lesion which required a biopsy for a definitive diagnosis.

  3. High-performance copper alloy films for barrierless metallization

    Science.gov (United States)

    Lin, C. H.; Leau, W. K.; Wu, C. H.

    2010-11-01

    In this study, we observe useful properties of V1.1- and V0.8N0.4-bearing copper (Cu) films deposited on barrierless silicon (Si) substrates by a cosputtering process. The Cu98.8(V0.8N0.4), or Cu(VNx) for brevity, films exhibit low resistivity (2.9 μΩ cm) and minimal leakage current after annealing at temperatures up to 700 °C for 1 h; no detectable reaction occurs at the Cu/Si interface. These observations confirm the high thermal stability of Cu(VNx) films. Furthermore, since these films have good adhesion features, they can be used for barrierless Cu metallization.

  4. Determination of mercury in copper concentrates by amalgam gathering-atomic absorption spectrometry%汞齐捕集-原子吸收光谱法测定铜精矿中汞含量

    Institute of Scientific and Technical Information of China (English)

    郭芬; 苏明跃; 谷松海

    2011-01-01

    It only took 5-6 min to determine powdered copper concentrate at 253. 7 nm by a direct mercury analyzer without the need of sample digestion. In order to reduce the damage of mercury in sample to the instrument and guarantee the accuracy of determination results, the sampling amount was 0. 15 g. Meanwhile, single determination mode was used to reduce the memory effect of sample boat.The detection [imit of this method was 0. 2 μg/kg. The content of mercury in three national certified reference materials of copper concentrate with different content ranges was determined. The results were consistent with those obtained by national standard method. The relative standard deviations (RSD) were smaller than or equal to 4. 7 %, and the recoveries were 98 %-102%.%无需进行样品消化处理,铜精矿粉末样品在253.7 nm处用直接测汞仪进行分析,5~6 min即可获取结果.为减少样品中汞对仪器的毒害同时保证测定结果的准确,样品取样量选择为0.15 g;同时,采用单个测定方式可减少样品舟存在的记忆效应.方法的检出限为0.2μg/kg.对3个不同含量范围铜精矿国家标准物质中的汞进行测定,结果同国标法的测定结果一致,相对标准偏差≤4.7%,回收率为98%~102%.

  5. A Study of the Preparation and Properties of Antioxidative Copper Inks with High Electrical Conductivity.

    Science.gov (United States)

    Tsai, Chia-Yang; Chang, Wei-Chen; Chen, Guan-Lin; Chung, Cheng-Huan; Liang, Jun-Xiang; Ma, Wei-Yang; Yang, Tsun-Neng

    2015-12-01

    Conductive ink using copper nanoparticles has attracted much attention in the printed electronics industry because of its low cost and high electrical conductivity. However, the problem of easy oxidation under heat and humidity conditions for copper material limits the wide applications. In this study, antioxidative copper inks were prepared by dispersing the nanoparticles in the solution, and then conductive copper films can be obtained after calcining the copper ink at 250 °C in nitrogen atmosphere for 30 min. A low sheet resistance of 47.6 mΩ/□ for the copper film was measured by using the four-point probe method. Importantly, we experimentally demonstrate that the electrical conductivity of copper films can be improved by increasing the calcination temperature. In addition, these highly conductive copper films can be placed in an atmospheric environment for more than 6 months without the oxidation phenomenon, which was verified by energy-dispersive X-ray spectroscopy (EDS). These observations strongly show that our conductive copper ink features high antioxidant properties and long-term stability and has a great potential for many printed electronics applications, such as flexible display systems, sensors, photovoltaic cells, and radio frequency identification.

  6. Amalgam Contact Hypersensitivity Lesion: An Unusual Presentation ...

    African Journals Online (AJOL)

    Contact allergic reactions due to hypersensitivity to dental materials in professionals and .... it, incisional biopsy was done under local anesthesia and the specimen was sent ... minimal technique sensitivity, amalgam for long has been used for ...

  7. The thickness of amalgamations of graphs

    CERN Document Server

    Yang, Yan

    2012-01-01

    The thickness $\\theta(G)$ of a graph $G$ is the minimum number of planar spanning subgraphs into which the graph $G$ can be decomposed. As a topological invariant of a graph, it is a measurement of the closeness to planarity of a graph, and it also has important applications to VLSI design. In this paper, the thickness of graphs that are obtained by vertex-amalgamation and bar-amalgamation of any two graphs whose thicknesses are known are obtained, respectively. And the lower and upper bounds for the thickness of graphs that are obtained by edge-amalgamation and 2-vertex-amalgamation of any two graphs whose thicknesses are known are also derived, respectively.

  8. Marginal microfiltration in amalgam restorations. Review

    OpenAIRE

    Lahoud Salem, Víctor; Departamento Académico de Estomatología Rehabilitadora. Facultad de Odontología, Universidad Nacional Mayor de San Marcos, Lima. Perú.

    2014-01-01

    The present articule is review references from phenomenon of microfiltration in restorations with amalgam and yours consecuents in changes of color in the interface tooth-restorations, margin deterioted , sensitivity dentinarea postoperate, caries secondary and pulp inflamation. Besides naming the mechanicals for to reduce microfiltration, and yours effects for use of sealers dentinaries representation for the varnish cavitys and adhesive systens Conclusive indicate wath the amalgam is the ma...

  9. Radiochemical separation of gold by amalgam exchange

    Science.gov (United States)

    Ruch, R.R.

    1970-01-01

    A rapid and simple method for the radiochemical separation of gold after neutron activation. The technique is based on treatment with a dilute indium-gold amalgam, both chemical reduction and isotopic exchange being involved. The counting efficiency for 198Au in small volumes of the amalgam is good. Few interferences occur and the method is applicable to clays, rocks, salts and metals. The possibility of determining silver, platinum and palladium by a similar method is mentioned. ?? 1970.

  10. Highly Stable Transparent Electrodes Made from Copper Nanotrough Coated with AZO/Al2O3.

    Science.gov (United States)

    Li, Peng; Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Liu, Yichun

    2016-04-01

    Due to their high flexibility, high conductivity and high transparency in a wide spectrum range, metal nanowires and meshes are considered to be two of the most promising candidates to replace the traditional transparent conducting films, such as tin doped indium oxide. In this paper, transparent conducting films made from copper nanotroughs are prepared by the electrospinning of polymer fibers and subsequent thermal evaporation of copper. The advantages of the technique include low junction resistance, low cost and low preparation temperature. Although the copper nanotrough transparent conducting films exhibited a low sheet resistance (19.2 Ω/sq), with a high transmittance (88% at 550 nm), the instability of copper in harsh environments seriously hinders its applications. In order to improve the stability of the metal transparent conducting films, copper nanotroughs were coated with 39 nm thick aluminum-doped zinc oxide and 1 nm thick aluminum oxide films by atomic layer deposition. The optical and electrical measurements show that coating copper nanotrough with oxides barely reduces the transparency of the films. It is worth noting that conductive oxide coating can effectively protect copper nanotroughs from thermal oxidation or acidic corrosion, whilst maintaining the same flexibility as copper nanotroughs on its own.

  11. Turning tumor-promoting copper into an anti-cancer weapon via high-throughput chemistry.

    Science.gov (United States)

    Wang, F; Jiao, P; Qi, M; Frezza, M; Dou, Q P; Yan, B

    2010-01-01

    Copper is an essential element for multiple biological processes. Its concentration is elevated to a very high level in cancer tissues for promoting cancer development through processes such as angiogenesis. Organic chelators of copper can passively reduce cellular copper and serve the role as inhibitors of angiogenesis. However, they can also actively attack cellular targets such as proteasome, which plays a critical role in cancer development and survival. The discovery of such molecules initially relied on a step by step synthesis followed by biological assays. Today high-throughput chemistry and high-throughput screening have significantly expedited the copper-binding molecules discovery to turn "cancer-promoting" copper into anti-cancer agents.

  12. Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

    Science.gov (United States)

    Miller, M. K.; Powers, K. A.; Nanstad, R. K.; Efsing, P.

    2013-06-01

    The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs) designed and supplied by Westinghouse Electric Company, with commercial operation in 1981 and 1983, respectively. The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impact 41-J shifts and corresponding fluences are 192 °C at 5.0 × 1023 n/m2 (>1 MeV) for Unit 3 and 162 °C at 6.0 × 1023 n/m2 (>1 MeV) for Unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel-manganese-silicon phases. Atom probe tomography measurements have revealed ˜2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese-nickel-silicon-enriched precipitates rather than changes in their size or number density.

  13. Laser-Assisted Reduction of Highly Conductive Circuits Based on Copper Nitrate for Flexible Printed Sensors

    Science.gov (United States)

    Bai, Shi; Zhang, Shigang; Zhou, Weiping; Ma, Delong; Ma, Ying; Joshi, Pooran; Hu, Anming

    2017-10-01

    Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment, health monitoring, and medical care sectors. In this work, conducting copper electrodes were fabricated on polydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 μΩ cm was achieved on 40-μm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness. This in situ fabrication method leads to a path toward electronic devices on flexible substrates.[Figure not available: see fulltext.

  14. Carnitine supplementation modulates high dietary copper-induced oxidative toxicity and reduced performance in laying hens.

    Science.gov (United States)

    Güçlü, Berrin Kocaoğlu; Kara, Kanber; Çakır, Latife; Çetin, Ebru; Kanbur, Murat

    2011-12-01

    This experiment was conducted to evaluate the effects of L-carnitine on performance, egg quality and certain biochemical parameters in laying hens fed a diet containing high levels of copper proteinate. Forty-eight 42-week-old laying hens were divided into four groups with four replicates. The laying hens were fed with a basal diet (control) or the basal diet supplemented with either 400 mg carnitine (Car)/kg diet, 800 mg copper proteinate (CuP)/kg diet or 400 mg carnitine + 800 mg copper (Car+CuP)/kg diet, for 6 weeks. Supplemental CuP decreased feed consumption (p supplemental CuP and Car+CuP. Supplemental CuP caused an increase in plasma malondialdehyde (p carnitine and copper combination may prevent the possible adverse effects of high dietary copper on performance and lipid peroxidation in hens.

  15. Low copper and high manganese levels in prion protein plaques

    Science.gov (United States)

    Johnson, Christopher J.; Gilbert, P.U.P.A.; Abrecth, Mike; Baldwin, Katherine L.; Russell, Robin E.; Pedersen, Joel A.; McKenzie, Debbie

    2013-01-01

    Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of copper and increased levels of manganese are associated with disease. The objectives of this study were to: (1) assess copper and manganese levels in healthy and TSE-infected Syrian hamster brain homogenates; (2) determine if the distribution of these metals can be mapped in TSE-infected brain tissue using X-ray photoelectron emission microscopy (X-PEEM) with synchrotron radiation; and (3) use X-PEEM to assess the relative amounts of copper and manganese in prion plaques in situ. In agreement with studies of other TSEs and species, we found reduced brain levels of copper and increased levels of manganese associated with disease in our hamster model. We also found that the in situ levels of these metals in brainstem were sufficient to image by X-PEEM. Using immunolabeled prion plaques in directly adjacent tissue sections to identify regions to image by X-PEEM, we found a statistically significant relationship of copper-manganese dysregulation in prion plaques: copper was depleted whereas manganese was enriched. These data provide evidence for prion plaques altering local transition metal distribution in the TSE-infected central nervous system.

  16. GRCop-84: A High-Temperature Copper Alloy for High-Heat-Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2005-01-01

    GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) is a new high-temperature copper-based alloy. It possesses excellent high-temperature strength, creep resistance and low-cycle fatigue up to 700 C (1292 F) along with low thermal expansion and good conductivity. GRCop-84 can be processed and joined by a variety of methods such as extrusion, rolling, bending, stamping, brazing, friction stir welding, and electron beam welding. Considerable mechanical property data has been generated for as-produced material and following simulated braze cycles. The data shows that the alloy is extremely stable during thermal exposures. This paper reviews the major GRCop-84 mechanical and thermophysical properties and compares them to literature values for a variety of other high-temperature copper-based alloys.

  17. Effects of Dietary Different Doses of Copper and High Fructose Feeding on Rat Fecal Metabolome.

    Science.gov (United States)

    Wei, Xiaoli; Song, Ming; Yin, Xinmin; Schuschke, Dale A; Koo, Imhoi; McClain, Craig J; Zhang, Xiang

    2015-09-04

    The gut microbiota plays a critical role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Increased fructose consumption and inadequate copper intake are two critical risk factors in the development of NAFLD. To gain insight into the role of gut microbiota, fecal metabolites, obtained from rats exposed to different dietary levels of copper with and without high fructose intake for 4 weeks, were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF MS). In parallel, liver tissues were assessed by histology and triglyceride assay. Our data showed that high fructose feeding led to obvious hepatic steatosis in both marginal copper deficient rats and copper supplementation rats. Among the 38 metabolites detected with significant abundance alteration between groups, short chain fatty acids were markedly decreased with excessive fructose intake irrespective of copper levels. C15:0 and C17:0 long chain fatty acids, produced only by bacteria, were increased by either high copper level or high fructose intake. In addition, increased fecal urea and malic acid paralleled the increased hepatic fat accumulation. Collectively, GC × GC-TOF MS analysis of rat fecal samples revealed distinct fecal metabolome profiles associated with the dietary high fructose and copper level, with some metabolites possibly serving as potential noninvasive biomarkers of fructose induced-NAFLD.

  18. Radiochemical separation of gallium by amalgam exchange

    Science.gov (United States)

    Ruch, R.R.

    1969-01-01

    An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

  19. Proximal Contact Repair of Complex Amalgam Restorations.

    Science.gov (United States)

    Zguri, M N; Casey, J A; Jessup, J P; Vandewalle, K S

    2017-01-12

    The carving of a complex amalgam restoration may occasionally result in light proximal contact with the adjacent tooth. The purpose of this study was to investigate the strength of complex amalgam restorations repaired with a proximal slot amalgam preparation. Extracted human third molars of similar coronal size were sectioned 1 mm apical to the height of the contour using a saw and were randomly distributed into 9 groups of 10 teeth each. One pin was placed at each line angle of the flattened dentinal tooth surface. A metal matrix band was placed and an admixed alloy was condensed and carved to create a full crown contour but with a flat occlusal surface. A proximal slot was prepared with or without a retention groove and repaired using a single-composition spherical amalgam 15 minutes, 24 hours, one week, or six months after the initial crown condensation. The specimens were stored for 24 hours in 37°C water before fracture at the marginal ridge using a round-ended blade in a universal testing machine. The control group was not repaired. The mean maximum force in newtons and standard deviation were determined per group. Data were analyzed with a 2-way analysis of variance as well as Tukey and Dunnett tests (α=0.05). Significant differences were found between groups based on type of slot preparation (p=0.017) but not on time (p=0.327), with no significant interaction (p=0.152). No significant difference in the strength of the marginal ridge was found between any repair group and the unrepaired control group (p>0.076). The proximal repair strength of a complex amalgam restoration was not significantly different from an unrepaired amalgam crown. Placing a retention groove in the proximal slot preparation resulted in significantly greater fracture strength than a slot with no retention grooves. Time of repair had no significant effect on the strength of the repair.

  20. Composite veneering of complex amalgam restorations.

    Science.gov (United States)

    Demarco, Flávio Fernando; Zanchi, César Henrique; Bueno, Márcia; Piva, Evandro

    2007-01-01

    In large posterior cavities, indirect restorations could provide improved performance when compared to direct restorations, but with higher cost and removal of sound tooth structure. Improved mechanical properties have resulted in good clinical performance for amalgam in large cavities but without an esthetic appearance. Resin composites have become popular for posterior restorations, mainly because of good esthetic results. A restorative technique is presented that combines the esthetic properties of directly bonded resin composite and the wide range of indications for amalgam in stress-bearing areas.

  1. FREE FISHER INFORMATION AND AMALGAMATED FREENESS

    Institute of Scientific and Technical Information of China (English)

    孟彬; 郭懋正; 曹小红

    2004-01-01

    The notion of operator-valued free Fisher information was introduced.It is a generalization of free Fisher information which was defined by D.Voiculescu on tracial von Neumann algebras.It is proved that the operator-valued free Fisher information is closely related to amalgamated freeness,i.e.,the operator-valued free Fisher information of some random variables is additive if and only if these random variables are a free family with amalgamation over a subalgebra.Cramer-Rao inequality in operator-valued settings is also obtained.

  2. GRCop-84: A High Temperature Copper-based Alloy For High Heat Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2005-01-01

    While designed for rocket engine main combustion chamber liners, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) offers potential for high heat flux applications in industrial applications requiring a temperature capability up to approximately 700 C (1292 F). GRCop-84 is a copper-based alloy with excellent elevated temperature strength, good creep resistance, long LCF lives and enhanced oxidation resistance. It also has a lower thermal expansion than copper and many other low alloy copper-based alloys. GRCop-84 can be manufactured into a variety of shapes such as tubing, bar, plate and sheet using standard production techniques and requires no special production techniques. GRCop-84 forms well, so conventional fabrication methods including stamping and bending can be used. GRCop-84 has demonstrated an ability to be friction stir welded, brazed, inertia welded, diffusion bonded and electron beam welded for joining to itself and other materials. Potential applications include plastic injection molds, resistance welding electrodes and holders, permanent metal casting molds, vacuum plasma spray nozzles and high temperature heat exchanger applications.

  3. Tensile and electrical properties of high-strength high-conductivity copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    Electrical conductivity and tensile properties have been measured on an extruded and annealed CuCrNb dispersion strengthened copper alloy which has been developed for demanding aerospace high heat flux applications. The properties of this alloy are somewhat inferior to GlidCop dispersion strengthened copper and prime-aged CuCrZr over the temperature range of 20--500 C. However, if the property degradation in CuCrZr due to joining operations and the anisotropic properties of GlidCop in the short transverse direction are taken into consideration, CuCrNb may be a suitable alternative material for high heat flux structural applications in fusion energy devices. The electrical conductivity and tensile properties of CuCrZr that was solution annealed and then simultaneously aged and diffusion bonded are also summarized. A severe reduction in tensile elongation is observed in the diffusion bonded joint, particularly if a thin copper shim is not placed in the diffusion bondline.

  4. Effect of electrolysis parameters on the morphologies of copper powder obtained at high current densities

    Directory of Open Access Journals (Sweden)

    Orhan Gökhan

    2012-01-01

    Full Text Available The effects of copper ion concentrations and electrolyte temperature on the morphologies and on the apparent densities of electrolytic copper powders at high current densities under galvanostatic regime were examined. These parameters were evaluated by the current efficiency of hydrogen evolution. In addition, scanning electron microscopy was used for analyzing the morphology of the copper powders. It was found that the morphology was dependent over the copper ion concentration and electrolyte temperature under same current density (CD conditions. At 150 mA cm-2 and the potential of 1000±20 mV (vs. SCE, porous and disperse copper powders were obtained at low concentrations of Cu ions (0.120 M Cu2+ in 0.50 M H2SO4. Under this condition, high rate of hydrogen evolution reaction took place parallel to copper electrodeposition. The morphology was changed from porous, disperse and cauliflower-like to coral-like, shrub-like and stalk-stock like morphology with the increasing of Cu ion concentrations towards 0.120 M, 0.155 M, 0.315 M, 0.475 M and 0.630 M Cu2+ in 0.5 M H2SO4 respectively at the same CD. Similarly, as the temperature was increased, powder morphology and apparent density were observed to be changed. The apparent density values of copper powders were found to be suitable for many of the powder metallurgy applications.

  5. High performance transparent conductor of graphene wrapped copper/nickel microgrids

    Science.gov (United States)

    Wu, Wei; Tassi, Nancy G.; Walls, Dennis J.; Zhang, Lei; Willner, Bruce

    2014-12-01

    A high performance, highly stable transparent conducting structure based on microscale copper/nickel grids wrapped with graphene is presented. Graphene is selectively deposited on the surfaces of the microgrids by atmospheric pressure chemical vapor deposition method. The optical transmittance of the copper/nickel microgrid sample is ˜80% over the visible and near-infrared spectra with a very small sheet resistance of ˜0.58 Ω/sq. After the high temperature deposition of graphene, the sample's transmittance increases to be ˜90% due to the line width reduction of the microgrids while the sheet resistance also increases to ˜5 Ω/sq. The graphene layer is deposited to keep the copper/nickel surfaces from being oxidized in the air. Both stability testing and composition spectra results confirm the long-term stability of the copper/nickel microgrids wrapped with graphene.

  6. Investigation of High-Temperature Slag/Copper/Spinel Interactions

    Science.gov (United States)

    De Wilde, Evelien; Bellemans, Inge; Campforts, Mieke; Guo, Muxing; Blanpain, Bart; Moelans, Nele; Verbeken, Kim

    2016-12-01

    An important cause for the mechanical entrainment of copper droplets in slags during primary and secondary copper production is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. In the present study, the interactions between the three phases involved (slag-Cu droplets-spinel solids) were investigated using an adapted sessile drop experiment, combined with detailed microstructural investigation of the interaction zone. An industrially relevant synthetic PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO slag system, a MgAl2O4 spinel particle, and pure copper were examined with electron microscopy after their brief interaction at 1523 K (1250 °C). Based on the experimental results, a mechanism depending on the interlinked dissolved Cu and oxygen contents within the slag is proposed to describe the origin of the phenomenon of sticking Cu alloy droplets. In addition, the oxygen potential gradient across the phases ( i.e., liquid Cu, slag, and spinel) appears to affect the Cu entrainment, as deduced from a microstructural analysis.

  7. Investigation of High-Temperature Slag/Copper/Spinel Interactions

    Science.gov (United States)

    De Wilde, Evelien; Bellemans, Inge; Campforts, Mieke; Guo, Muxing; Blanpain, Bart; Moelans, Nele; Verbeken, Kim

    2016-09-01

    An important cause for the mechanical entrainment of copper droplets in slags during primary and secondary copper production is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. In the present study, the interactions between the three phases involved (slag-Cu droplets-spinel solids) were investigated using an adapted sessile drop experiment, combined with detailed microstructural investigation of the interaction zone. An industrially relevant synthetic PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO slag system, a MgAl2O4 spinel particle, and pure copper were examined with electron microscopy after their brief interaction at 1523 K (1250 °C). Based on the experimental results, a mechanism depending on the interlinked dissolved Cu and oxygen contents within the slag is proposed to describe the origin of the phenomenon of sticking Cu alloy droplets. In addition, the oxygen potential gradient across the phases (i.e., liquid Cu, slag, and spinel) appears to affect the Cu entrainment, as deduced from a microstructural analysis.

  8. High performance 3D printed electronics using electroless plated copper

    OpenAIRE

    Jin Rong Jian; Taeil Kim; Jae Sung Park; Jiacheng Wang; Woo Soo Kim

    2017-01-01

    This paper presents design and performance validation of 3D printed electronic components, 3D toroidal air-core inductors, fabricated by multi-material based Fused Deposition Modelling (FDM) 3D printing technology and electroless copper plating. Designs of toroidal inductor is investigated with different core shapes and winding numbers; circular and half-circular cores with 10 and 13 turns of windings...

  9. Novel Amalgams for In-Space Parts Fabrication

    Science.gov (United States)

    Cochran, Calvin; VanHoose, James R.; Grugel, Richard N.

    2012-01-01

    Sound amalgams can be fabricated by substituting Ga-In liquid for mercury; Cu-coated steel fibers bond well with the amalgam components. Inclusion of steel fibers significantly improved mechanical properties. An application scenario utilizing amalgams for in-space parts fabrication and repair was suggested. Procedure and materials need to be optimized

  10. 21 CFR 872.3110 - Dental amalgam capsule.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification. A dental amalgam capsule is a container device in which silver alloy is intended to be mixed with...

  11. Bond strength of resin composite to differently conditioned amalgam

    NARCIS (Netherlands)

    Ozcan, M; Vallittu, PK; Huysmans, MC; Kalk, W; Vahlberg, T

    2006-01-01

    Bulk fracture of teeth, where a part of the amalgam restoration and/or the cusp is fractured, is a common clinical problem. The aim of this study was to evaluate the effect of different surface conditioning methods on the shear bond strength of a hybrid resin composite to fresh amalgam. Amalgams (N

  12. Bond strength of resin composite to differently conditioned amalgam

    NARCIS (Netherlands)

    Ozcan, M; Vallittu, PK; Huysmans, MC; Kalk, W; Vahlberg, T

    Bulk fracture of teeth, where a part of the amalgam restoration and/or the cusp is fractured, is a common clinical problem. The aim of this study was to evaluate the effect of different surface conditioning methods on the shear bond strength of a hybrid resin composite to fresh amalgam. Amalgams (N

  13. Biomolecule-assisted synthesis of highly stable dispersions of water-soluble copper nanoparticles.

    Science.gov (United States)

    Xiong, Jing; Wu, Xue-dong; Xue, Qun-ji

    2013-01-15

    Water-soluble and highly stable dispersions of copper nanoparticles were obtained using a biomolecule-assisted synthetic method. Dopamine was utilized as both reducing and capping agent in aqueous medium. The successful formation of DA-stabilized copper particles was demonstrated by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), Zeta potential measurement, and Fourier transform infrared spectroscopy (FT-IR). The mechanism of dopamine on the effective reduction and excellent stability of copper nanoparticles was also discussed. This facile biomolecule-assisted technique may provide a useful tool to synthesize other nanoparticles that have potential application in biotechnology.

  14. Repair of amalgam restorations with composite resin and bonded amalgam: A microleakage study

    Directory of Open Access Journals (Sweden)

    Daniela Araújo Veloso Popoff

    2011-01-01

    Conclusions: The use of adhesive systems significantly affected the ability to seal the repair/ tooth interface. However, at the level of the repair/restoration interface, the bonded amalgam technique may increase microleakage.

  15. The Synthesis of Highly Aligned Cupric Oxide Nanowires by Heating Copper Foil

    Directory of Open Access Journals (Sweden)

    Jianbo Liang

    2011-01-01

    Full Text Available We have investigated the effects of grain size and orientation of copper substrates for the growth of cupric oxide nanowires by thermal oxidation method. Long, less-roughness, high-density, and aligned cupric oxide nanowires have been synthesized by heating (200 oriented copper foils with small grain size in air gas. Long and aligned nanowires of diameter around 80 nm can only be formed within a short temperature range from 400 to 700°C. On the other hand, uniform, smooth-surface, and aligned nanowires were not formed in the case of larger crystallite size of copper foils with (111 and (200 orientation. Smaller grain size of copper foil with (200 orientation is favorable for the growth of highly aligned, smooth surface, and larger-diameter nanowires by thermal oxidation method.

  16. The Origin of High Thermal Conductivity and Ultralow Thermal Expansion in Copper-Graphite Composites.

    Science.gov (United States)

    Firkowska, Izabela; Boden, André; Boerner, Benji; Reich, Stephanie

    2015-07-08

    We developed a nanocomposite with highly aligned graphite platelets in a copper matrix. Spark plasma sintering ensured an excellent copper-graphite interface for transmitting heat and stress. The resulting composite has superior thermal conductivity (500 W m(-1) K(-1), 140% of copper), which is in excellent agreement with modeling based on the effective medium approximation. The thermal expansion perpendicular to the graphite platelets drops dramatically from ∼20 ppm K(-1) for graphite and copper separately to 2 ppm K(-1) for the combined structure. We show that this originates from the layered, highly anisotropic structure of graphite combined with residual stress under ambient conditions, that is, strain-engineering of the thermal expansion. Combining excellent thermal conductivity with ultralow thermal expansion results in ideal materials for heat sinks and other devices for thermal management.

  17. Amalgam tattoo (amalgam pigmentation) of the oral mucosa: clinical manifestations, diagnosis and treatment.

    Science.gov (United States)

    Buchner, A

    2004-07-01

    Amalgam tattoo is an iatrogenic lesion caused by traumatic implantation of dental amalgam into soft tissue. Amalgam tattoo is the most common localized pigmented lesion in the mouth. In a study of a mass screening oral examination in the United States, it was found in about 0.4-0.9% of the adult population and in Sweden in about 8%. Clinically, amalgam tattoo presents as a dark gray or blue, flat macule located adjacent to a restored tooth. Most are located on the gingiva and alveolar mucosa followed by the buccal mucosa and the floor of the mouth. Microscopic examination reveals that amalgam is present in the tissues in two forms: as irregular dark, solid fragments of metal or as numerous, discrete fine, brown or black granules dispersed along collagen bundles and around small blood vessels and nerves. In most lesions, it is presented in both forms. The biologic response to the amalgam is related to particle size, quantity and elemental composition of the amalgam. Large fragments often become surrounded by dense fibrous connective tissue. Smaller particles are associated with mild to moderate chronic inflammatory response with individual macrophages engulfing small amalgam particles. Occasionally, the reaction takes the form of foreign body granuloma in which macrophages and multinucleated giant cells are present. Some of the multinucleated giant cells also contain amalgam particles. Diagnosis of amalgam tattoo is usually obvious from the location and clinical appearance. A radiograph is recommended to confirm the presence of metallic particles, but absence of radiographic evidence does not rule out the possibility, since particles are often too fine or widely dispersed to be visible on radiographs. When there is no radiographic evidence or an adjacent restored tooth, biopsy is recommended to rule out an early melanoma. Once the diagnosis of amalgam tattoo has been established, no additional treatment is necessary except for cosmetic reasons. If the pigmentation

  18. Boundedness of positive operators on weighted amalgams

    Directory of Open Access Journals (Sweden)

    Aguilar Cañestro María Isabel

    2011-01-01

    Full Text Available Abstract In this article, we characterize the pairs (u, v of positive measurable functions such that T maps the weighted amalgam in (Lp (u, ℓ q for all , where T belongs to a class of positive operators which includes Hardy operators, maximal operators, and fractional integrals. 2000 Mathematics Subject Classification 26D10, 26D15 (42B35

  19. Dental amalgam: is this the end?

    Science.gov (United States)

    Taut, Cristina

    Dental amalgam is a reliable and effective restorative material with a well-established role in modern dentistry. Throughout the years its mercury content and the risks posed to human health were main topics of interest for many scientists. This paper offers a review of the scientific literature on the health and environmental impact of mercury in dentistry published over the last decade. A variety of peer-reviewed, epidemiological and large-scale clinical studies on dental amalgam, as well as published reports of professional and governmental bodies, were organised thematically and analysed. The most relevant findings of the aforementioned literature are reported. No reliance has been placed on unpublished work or publicly available opinions that are not scientifically based. In order to offer an appropriate view on the topic the toxicology, health impacts and possible environmental threats are briefly presented in relation to the relevant literature published in the last ten years. It is almost unanimously accepted that dental amalgam is a safe material, with little or insignificant adverse effect on general health. However, current and mostly unfounded environmental concerns may result in the implementation of new across the board legislation that could lead to a global dental amalgam "phase out".

  20. Amalgam tattoo: a cause of sinusitis?

    Science.gov (United States)

    Parizi, José Luiz Santos; Nai, Gisele Alborghetti

    2010-01-01

    Little attention has been paid to the toxicity of silver amalgam fillings, which have been used over the centuries in Dentistry. Amalgam particles may accidentally and/or traumatically be embedded into the submucosal tissue during placement of a restoration and perpetuate in such area. This article presents a case of amalgam tattoo and investigates whether it is related to the patient's repeated episodes of sinusitis. The patient was a 46-year-old woman with a 2 mm diameter radiopaque lesion in the right oral mucosa detected on a panoramic radiograph and presented as a black macula clinically. A complete surgical resection was carried out. The histopathological examination revealed deposits of dark-brownish pigments lining the submucosal tissue with adjacent lymphocytic inflammatory infiltrate and multinucleated giant cells phagocyting pigments. There was a negative staining for both iron and melanin. One year after lesion removal, the patient reported that the sinusitis crises had ceased after repeated episodes for years. It may be speculated that the inflammatory process related to amalgam tattoo seems to lead to a local immune response that causes sinusitis because it enhances the human leukocyte antigen DR (HLA-DR) tissue expression.

  1. Amalgam tattoo: a cause of sinusitis?

    Directory of Open Access Journals (Sweden)

    José Luiz Santos Parizi

    2010-02-01

    Full Text Available Little attention has been paid to the toxicity of silver amalgam fillings, which have been used over the centuries in Dentistry. Amalgam particles may accidentally and/or traumatically be embedded into the submucosal tissue during placement of a restoration and perpetuate in such area. This article presents a case of amalgam tattoo and investigates whether it is related to the patient's repeated episodes of sinusitis. The patient was a 46-year-old woman with a 2 mm diameter radiopaque lesion in the right oral mucosa detected on a panoramic radiograph and presented as a black macula clinically. A complete surgical resection was carried out. The histopathological examination revealed deposits of dark-brownish pigments lining the submucosal tissue with adjacent lymphocytic inflammatory infiltrate and multinucleated giant cells phagocyting pigments. There was a negative staining for both iron and melanin. One year after lesion removal, the patient reported that the sinusitis crises had ceased after repeated episodes for years. It may be speculated that the inflammatory process related to amalgam tattoo seems to lead to a local immune response that causes sinusitis because it enhances the human leukocyte antigen DR (HLA-DR tissue expression.

  2. Do Dental Resin Composites Accumulate More Oral Biofilms and Plaque than Amalgam and Glass Ionomer Materials?

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2016-11-01

    Full Text Available A long-time drawback of dental composites is that they accumulate more biofilms and plaques than amalgam and glass ionomer restorative materials. It would be highly desirable to develop a new composite with reduced biofilm growth, while avoiding the non-esthetics of amalgam and low strength of glass ionomer. The objectives of this study were to: (1 develop a protein-repellent composite with reduced biofilms matching amalgam and glass ionomer for the first time; and (2 investigate their protein adsorption, biofilms, and mechanical properties. Five materials were tested: A new composite containing 3% of protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC; the composite with 0% MPC as control; commercial composite control; dental amalgam; resin-modified glass ionomer (RMGI. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU, and lactic acid production. Composite with 3% MPC had flexural strength similar to those with 0% MPC and commercial composite control (p > 0.1, and much greater than RMGI (p < 0.05. Composite with 3% MPC had protein adsorption that was only 1/10 that of control composites (p < 0.05. Composite with 3% MPC had biofilm CFU and lactic acid much lower than control composites (p < 0.05. Biofilm growth, metabolic activity and lactic acid on the new composite with 3% MPC were reduced to the low level of amalgam and RMGI (p > 0.1. In conclusion, a new protein-repellent dental resin composite reduced oral biofilm growth and acid production to the low levels of non-esthetic amalgam and RMGI for the first time. The long-held conclusion that dental composites accumulate more biofilms than amalgam and glass ionomer is no longer true. The novel composite is promising to finally overcome the major biofilm-accumulation drawback of dental composites in order to reduce biofilm acids and secondary caries.

  3. Effect of composite/amalgam thickness on fracture resistance of maxillary premolar teeth, restored with combined amalgam-composite restorations

    Science.gov (United States)

    Firouzmandi, Maryam; Doozandeh, Maryam; Abbasi, Sanaz

    2016-01-01

    Background Combined amalgam-composite restorations have been used through many years to benefit from the advantages of both dental amalgam and composite resin. Two variations have been mentioned for this technique, this study investigated the fracture resistance of maxillary premolar teeth with extended mesio-occluso-distal (MOD) cavities, restored with the two variations of combined amalgam-composite restorations. Material and Methods Sixty intact extracted premolar teeth were randomly divided into 6 groups (G1-G6) of 10 teeth. G1; consisted of intact teeth and G2; consisted of teeth with MOD preparations were assigned as the positive and negative control groups respectively. Other experimental groups after MOD preparations were as follows: G3, amalgam restoration; G4, composite restoration; G5 combined amalgam-composite restoration with amalgam placement only on 1mm of the gingival floor of the proximal boxes; G6, combined amalgam-composite restoration with amalgam placement to the height of contact area of the proximal surface of the tooth. Fracture strength of the specimens was measured and the data were analyzed using one-way analysis of variance (ANOVA). The level of significance was Pamalgam-composite restoration was similar to that achieved with composite restoration alone and more than that of amalgam restoration alone. It can be concluded that the thickness of amalgam in combined amalgam-composite restorations did not affect fracture resistance of the teeth. Key words:Amalgam, composite, fracture resistance, restoration. PMID:27398176

  4. Distribution of toxic elements in teeth treated with amalgam using μ-energy dispersive X-ray fluorescence

    Science.gov (United States)

    Guerra, M.; Ferreira, C.; Carvalho, M. L.; Santos, J. P.; Pessanha, S.

    2016-08-01

    Over the years, the presence of mercury in amalgam fillings has raised some safety concerns. Amalgam is one of the most commonly used tooth fillings and contains approximately 50% of elemental mercury and 50% of other metals, mostly silver, tin and copper. Amalgam can release small amounts of mercury vapor over time, and patients can absorb these vapors by inhaling or ingesting them. In this study, 10 human teeth treated with dental amalgam were analyzed using energy dispersive X-ray fluorescence (EDXRF) to study the diffusion of its constituents, Ag, Cu, Sn and Hg. The used EDXRF setup, makes use of a polycapillary lens to focus radiation up to 25 μm allowing the mapping of the elemental distribution in the samples. Quantification was performed using the inbuilt software based on the Fundamental Parameters method for bulk samples, considering a hydroxyapatite matrix. The teeth were longitudinally cut and each slice was scanned from the surface enamel to the inner region (dentin and pulp cavity). Mercury concentration profiles show strong levels of this element close to the amalgam region, decreasing significantly in the dentin, and increasing again up to 40,000 μg·g- 1 in the cavity were the pulp used to exist when the tooth was vital.

  5. High performance 3D printed electronics using electroless plated copper

    Science.gov (United States)

    Jian, Jin Rong; Kim, Taeil; Park, Jae Sung; Wang, Jiacheng; Kim, Woo Soo

    2017-03-01

    This paper presents design and performance validation of 3D printed electronic components, 3D toroidal air-core inductors, fabricated by multi-material based Fused Deposition Modelling (FDM) 3D printing technology and electroless copper plating. Designs of toroidal inductor is investigated with different core shapes and winding numbers; circular and half-circular cores with 10 and 13 turns of windings. Electroless plated copper thin film ensures 3D printed toroidal plastic structures to possess inductive behaviors. The inductance is demonstrated reliably with an applied source frequency from 100 kHz to 2 MHz as designs vary. An RL circuit is utilized to test the fabricated inductors' phase-leading characteristics with corresponding phase angle changes.

  6. High performance 3D printed electronics using electroless plated copper

    Directory of Open Access Journals (Sweden)

    Jin Rong Jian

    2017-03-01

    Full Text Available This paper presents design and performance validation of 3D printed electronic components, 3D toroidal air-core inductors, fabricated by multi-material based Fused Deposition Modelling (FDM 3D printing technology and electroless copper plating. Designs of toroidal inductor is investigated with different core shapes and winding numbers; circular and half-circular cores with 10 and 13 turns of windings. Electroless plated copper thin film ensures 3D printed toroidal plastic structures to possess inductive behaviors. The inductance is demonstrated reliably with an applied source frequency from 100 kHz to 2 MHz as designs vary. An RL circuit is utilized to test the fabricated inductors’ phase-leading characteristics with corresponding phase angle changes.

  7. Effect of high soil copper concentration on mycorrhizal grapevines

    Science.gov (United States)

    Nogales, Amaia; Santos, Erika S.; Viegas, Wanda; Aran, Diego; Pereira, Sofia H.; Vidigal, Patricia; Lopes, Carlos M.; Abreu, M. Manuela

    2017-04-01

    Repeated application of Copper (Cu) based fungicides in vineyards since the end of the 19th century has led to a significant increase in the concentration of this chemical element in many viticultural soils. Although Cu is an essential micronutrient for most organisms, it can be toxic for the development and survival of plants and soil (micro)organisms at high concentrations and eventually lead to yield loses in viticulture, as it negatively affects key physiological and biogeochemical processes. However, some soil microorganisms, including arbuscular mycorrhizal fungi (AMF), have developed adaptive mechanisms for persistence in environments with supra-optimal levels of essential elements or in the presence of harmful ones, as well as for increasing plant tolerance to such abiotic stress conditions. The objective of this work was to evaluate the effect of a high total soil concentration of Cu on microbial soil activity as well as on the development of mycorrhizal and non-mycorrhizal grapevines. A microcosm assay was set up under greenhouse and controlled conditions. Touriga Nacional grapevine variety plants grafted onto 1103P rootstocks were inoculated either with the AMF Rhizophagus irregularis or Funneliformis mosseae, or were left as non-inoculated controls. After three months, they were transplanted to containers filled with 4 kg of a sandy soil (pH: 7.0; electrical conductivity: 0.08 mS/cm; [organic C]: 5.6 g/kg; [N-NO3]: 1.1 mg/kg; [N-NH4]: 2.5 mg/kg; [extractable K]: 45.1 mg/kg; [extractable P]: 52.3 mg/kg), collected near to a vineyard in Pegões (Portugal). Two treatments were carried out: with and without Cu application. The soil with high Cu concentration was prepared by adding 300 mg Cu/kg (in the form of an aqueous solution of CuSO4·5H2O) followed by an incubation during four weeks in plastic bags at room temperature in dark. Physico-chemical soil characteristics (pH, electrical conductivity and nutrients concentration in available fraction), soil

  8. Copper Decoration of Carbon Nanotubes and High Resolution Electron Microscopy

    Science.gov (United States)

    Probst, Camille

    A new process of decorating carbon nanotubes with copper was developed for the fabrication of nanocomposite aluminum-nanotubes. The process consists of three stages: oxidation, activation and electroless copper plating on the nanotubes. The oxidation step was required to create chemical function on the nanotubes, essential for the activation step. Then, catalytic nanoparticles of tin-palladium were deposited on the tubes. Finally, during the electroless copper plating, copper particles with a size between 20 and 60 nm were uniformly deposited on the nanotubes surface. The reproducibility of the process was shown by using another type of carbon nanotube. The fabrication of nanocomposites aluminum-nanotubes was tested by aluminum vacuum infiltration. Although the infiltration of carbon nanotubes did not produce the expected results, an interesting electron microscopy sample was discovered during the process development: the activated carbon nanotubes. Secondly, scanning transmitted electron microscopy (STEM) imaging in SEM was analysed. The images were obtained with a new detector on the field emission scanning electron microscope (Hitachi S-4700). Various parameters were analysed with the use of two different samples: the activated carbon nanotubes (previously obtained) and gold-palladium nanodeposits. Influences of working distance, accelerating voltage or sample used on the spatial resolution of images obtained with SMART (Scanning Microscope Assessment and Resolution Testing) were analysed. An optimum working distance for the best spatial resolution related to the sample analysed was found for the imaging in STEM mode. Finally, relation between probe size and spatial resolution of backscattered electrons (BSE) images was studied. An image synthesis method was developed to generate the BSE images from backscattered electrons coefficients obtained with CASINO software. Spatial resolution of images was determined using SMART. The analysis shown that using a probe

  9. A Review on Dental Amalgam Corrosion and Its Consequences

    Directory of Open Access Journals (Sweden)

    M Fathi

    2004-02-01

    Full Text Available Dental amalgam is still the most useful restorative material for posterior teeth and has been successfully used for over a century. Dental amalgam has been widely used as a direct filling material due to its favorable mechanical properties as well as low cost and easy placement. However, the mercury it contains raises concerns about its biological toxicity and environmental hazard. Although in use for more than 150 years, dental amalgam has always been suspected more or less vigorously due to its alleged health hazard. Amalgam restorations often tarnish and corrode in oral environment. Corrosion of dental amalgam can cause galvanic action. Ion release as a result of corrosion is most important. Humans are exposed to mercury and other main dental metals via vapor or corrosion products in swallowed saliva and also direct absorption into blood from oral mucosa. During recent decades the use of dental amalgam has been discussed with respect to potential toxic effects of mercury components. In this article, the mechanisms of dental amalgam corrosion are described and results of researches are reviewed. It finally covers the corrosion of amalgams since this is the means by which metals, including mercury, can be released within oral cavity. Keywords: Dental amalgam, Amalgam corrosion, Biocompatibility, Mercury release, Amalgam restoration

  10. Laser-enhanced ionization detection of trace copper in high salt matrices.

    Science.gov (United States)

    Havrilla, G J; Carter, C C

    1987-09-01

    Laser-enhanced ionization (LEI) is used to determine trace levels of metals in high salt matrices, an analysis that is difficult by conventional methods. Copper is presented in detail to demonstrate the capability of the method. Three-dimensional spectra of the stepwise excitation of copper are presented which illustrate the one photon, stepwise, and two-photon transitions. Seven copper transitions have been studied for analytical utility, and detection limits have been determined for each. Ionization interferences were accommodated by both matrix matching and separation of the interferences using ion exchange resin. Absolute determinations at the 0.05-ng level are possible with the use of a Teflon microsampling cup for low volume quantitative analysis. In addition to copper, silver, cobalt, iron, and nickel have been detected within the same dye tuning range. Twelve new LEI transitions have been identified for these elements along with detection limits.

  11. Electrocrystallization of Monodisperse Nanocrystal Copper on Highly Oriented Pyrolytic Graphite Electrode

    Institute of Scientific and Technical Information of China (English)

    黄令; LEE,Eun-Sung; KIM,Kwang-Bum

    2005-01-01

    Mechanism of copper electrocrystallization on highly oriented pyrolytic graphite electrode from a solution of 1 mmol/L CuSO4 and 1.0 mol/L H2SO4 has been studied using cyclic voltammogram and chronoamperometry. The results show that in copper electrodeposition the charge-transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing centers. Reduction of Cu(Ⅱ) ions did not undergo underpotential deposition. The initial deposition kinetics of Cu electrocrystallization corresponds to a model including progressive nucleation and diffusion controlled growth. Copper nanocrystals with size of 75.6 nm and relative standard deviation of 9% can be obtained by modulation potential electrodeposition.

  12. Efectos de la corrosión en el sellado marginal de la interfase diente-amalgama: Un estudio in vitro Effects of corrosion in the marginal sealing of the tooth-amalgam inferface: An in vitro study

    Directory of Open Access Journals (Sweden)

    Marizoila Díaz

    2008-06-01

    Full Text Available OBJETIVO: evaluar la interfase diente-amalgama en restauraciones de alto contenido de cobre corroídas in Vitro. MÉTODOS: Se utilizaron 20 premolares sanos, restaurados con amalgamas, que fueron observados al microscopio electrónico de barrido previo y posteriormente a un proceso de corrosión inducido con solución de Cloruro de Sodio y Ácido Acético, durante 11 semanas. RESULTADOS: El 80% de las brechas de la interfase medidas del ángulo mesiovestibular y el 85 % del punto medio vestibular oclusal aumentaron, con un P=0,022 y P=0,006 respectivamente. CONCLUSIONES: De esta manera, bajo las condiciones de un estudio in Vitro, se evidencia que la corrosión influye negativamente en la capacidad de autosellado de la amalgama de alto contenido de cobreOBJECTIVE: to evaluate the tooth-amalgam interface in restorations with high copper content corroded in vitro. METHODS: 20 sound premolars restored with amalgam were used. They were observed on the previous scanning electronic microscope and later on they were subjected to a corrosion process induced with a solution of sodium chloride and acetic acid for 11 weeks. RESULTS: 80 % of the gaps of the interface measured from the mesiovestibular angle and 85 % of the occlusal vestibular middle point increased, with P=0.022 and P=0.006, respectively. CONCLUSIONS: This way, under the conditions of an in vitro study, it was proved that corrosion influences negatively on the self-sealing capacity of the amalgam with high copper content

  13. Electrodeposition of copper from a copper sulfate solution using a packed-bed continuous-recirculation flow reactor at high applied electric current

    OpenAIRE

    Meshaal F. Alebrahim; I.A. Khattab; Sharif, Adel O.

    2015-01-01

    The purpose of this study is mainly to investigate the performance of a packed-bed continuous-recirculation flow reactor at high applied electric current in removing copper, Cu(II), from simulated electrolyte by electrodeposition. The effects of pHo, circulation rate of flow, initial copper concentration, intensity of the applied current and the method of application of electric current, as to have a constant value during all the time of electrolysis or to be decreased with time, on copper el...

  14. Construction of a high efficiency copper adsorption bacterial system via peptide display and its application on copper dye polluted wastewater.

    Science.gov (United States)

    Maruthamuthu, Murali Kannan; Nadarajan, Saravanan Prabhu; Ganesh, Irisappan; Ravikumar, Sambandam; Yun, Hyungdon; Yoo, Ik-Keun; Hong, Soon Ho

    2015-11-01

    For the construction of an efficient copper waste treatment system, a cell surface display strategy was employed. The copper adsorption ability of recombinant bacterial strains displaying three different copper binding peptides were evaluated in LB Luria-Bertani medium (LB), artificial wastewater, and copper phthalocyanine containing textile dye industry wastewater samples. Structural characteristics of the three peptides were also analyzed by similarity-based structure modeling. The best binding peptide was chosen for the construction of a dimeric peptide display and the adsorption ability of the monomeric and dimeric peptide displayed strains were compared. The dimeric peptide displayed strain showed superior copper adsorption in all three tested conditions (LB, artificial wastewater, and textile dye industry wastewater). When the strains were exposed to copper phthalocyanine dye polluted wastewater, the dimeric peptide display [543.27 µmol/g DCW dry cell weight (DCW)] showed higher adsorption of copper when compared with the monomeric strains (243.53 µmol/g DCW).

  15. Influences of copper on solidification structure and hardening behavior of high chromium cast irons

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; XIONG Ji; FAN Hong-yuan; SHEN Bao-luo; GAO Sheng-ji

    2008-01-01

    The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated.The results show that the mierostructure of the as-cast high chromium cast irons consists of retained austenite,martensite and M7 C3 type eutectic carbide.When copper is added into high chromium cast irons,austenite and carbide contents are increased.The increased addition of copper content from 0%to 1.84%leads to the increase of austenite and carbide from 15.9%and 20.0% to 61.0%and 35.5%,respectively.In the process of sub-critical treatment,the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process,which causes the secondary hardening of the alloy under sub-critical treatment.High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.

  16. Electrodeposition of copper from a copper sulfate solution using a packed-bed continuous-recirculation flow reactor at high applied electric current

    Directory of Open Access Journals (Sweden)

    Meshaal F. Alebrahim

    2015-09-01

    Full Text Available The purpose of this study is mainly to investigate the performance of a packed-bed continuous-recirculation flow reactor at high applied electric current in removing copper, Cu(II, from simulated electrolyte by electrodeposition. The effects of pHo, circulation rate of flow, initial copper concentration, intensity of the applied current and the method of application of electric current, as to have a constant value during all the time of electrolysis or to be decreased with time, on copper electrodeposition and current efficiency are revealed. The results showed that the increase in pH (provided not lead to the deposition of Cu(OH2, initial concentration of the copper and flow rate increased the electrodeposition of copper as well as improved current efficiency. However, increasing intensity of the applied electric current led to an increase in the electrodeposition of copper and decreased electrical efficiency. It was also observed that reducing the intensity of applied electric current with time during the electrolysis process while maintaining other operating variables constant led to a significant reduction in the consumption of electrical energy used in the process of copper removal by electrodeposition; a reduction of 41.6% could be achieved.

  17. [Phase transition analysis of ancient bronze mirror surface tin amalgam in heating].

    Science.gov (United States)

    Zhang, Shao-yun; Qin, Ying

    2010-10-01

    Taking advantage of theta-theta scanning (vertical goniometer) sealed and ceramic X-ray tube full-automatic diffractometer, which can be heated and detected at the same time when the temperature is between normal temperature and 1200 degrees C, and X-ray fluorescence, and combining surface feature with character, high tin bronze mirror which had been daubed "tin amalgam" was detected and analyzed. It can prove that phase with Hg will disappear gradually when the sample is heated to the temperature higher than the boiling point of Hg; It indicates that bronze surface cannot be as a proof of "tin amalgam" used whether it contains Hg, moreover, it is not necessary that bronze mirror is covered with "tin amalgam" in terms of application.

  18. Human brain mercury levels related to exposure to amalgam fillings.

    Science.gov (United States)

    Ertaş, E; Aksoy, A; Turla, A; Karaarslan, E S; Karaarslan, B; Aydın, A; Eken, A

    2014-08-01

    The safety of dental amalgam as the primary material in dental restoration treatments has been debated since its introduction. It is widely accepted that amalgam restorations continuously release elemental mercury (Hg) vapor, which is inhaled and absorbed by the body and distributed to tissues, including the brain. The aim of the present study was to investigate whether the presence of amalgam fillings is correlated with brain Hg level. The Hg levels in the parietal lobes of the brains of 32 cadavers were analyzed with an atomic absorption spectrometer with the mercury hydride system. A total of 32 brain samples were tested; of these, 10 were from cadavers with amalgam fillings, while 22 of them were amalgam free. Hg was detected in 60.0% (6 of 10) of the samples in the amalgam group and in 36.3% (8 of 22) in the amalgam-free group. The average Hg level of the amalgam group was 0.97 ± 0.83 µg/g (minimum: 0.3 µg/g and maximum: 2.34 µg/g), and in the amalgam-free group, it was 1.06 ± 0.57 µg/g (minimum: 0.17 µg/g and maximum: 1.76 µg/g). The results of the present study showed no correlation between the presence of amalgam fillings and brain Hg level.

  19. Copper coated carbon fiber reinforced plastics for high and ultra high vacuum applications

    Science.gov (United States)

    Burri, F.; Fertl, M.; Feusi, P.; Henneck, R.; Kirch, K.; Lauss, B.; Rüttimann, P.; Schmidt-Wellenburg, P.; Schnabel, A.; Voigt, J.; Zenner, J.; Zsigmond, G.

    2014-03-01

    We have used copper-coated carbon fiber reinforced plastic (CuCFRP) for the construction of high and ultra-high vacuum recipients. The vacuum performance is found to be comparable to typical stainless steel used for this purpose. In test recipients we have reached pressures of 2E-8 mbar and measured a desorption rate of 1E-11 mbar*liter/s/cm^2; no degradation over time (2 years) has been found. Suitability for baking has been found to depend on the CFRP production process, presumably on the temperature of the autoclave curing. Together with other unique properties of CuCFRP such as low weight and being nearly non-magnetic, this makes it an ideal material for many high-end vacuum applications.

  20. Copper coated carbon fiber reinforced plastics for high and ultra high vacuum applications

    CERN Document Server

    Burri, F; Feusi, P; Henneck, R; Kirch, K; Lauss, B; Ruettimann, P; Schmidt-Wellenburg, P; Schnabel, A; Voigt, J; Zenner, J; Zsigmond, G

    2013-01-01

    We have used copper-coated carbon fiber reinforced plastic (CuCFRP) for the construction of high and ultra-high vacuum recipients. The vacuum performance is found to be comparable to typical stainless steel used for this purpose. In test recipients we have reached pressures of 2E-8 mbar and measured a desorption rate of 1E-11 mbar*liter/s/cm^2; no degradation over time (2 years) has been found. Suitability for baking has been found to depend on the CFRP production process, presumably on the temperature of the autoclave curing. Together with other unique properties of CuCFRP such as low weight and being nearly non-magnetic, this makes it an ideal material for many high-end vacuum applications.

  1. Provenance of the Neoproterozoic high-grade metasedimentary rocks of the arc-related Oriental Terrane of the Ribeira belt: Implications for Gondwana amalgamation

    Science.gov (United States)

    Lobato, Marcela; Heilbron, Monica; Torós, Bernardo; Ragatky, Diana; Dantas, Elton

    2015-11-01

    The Costeiro domain integrates the Oriental terrane of the Ribeira belt, which encompasses arc-related orthogneisses of the Rio Negro complex (ca.790-605 Ma), with a well-documented subduction signature, and the high-grade metasedimentary rocks of the São Fidélis group. The arc-related rocks intruded the lower unit of the São Fidélis group, while both units are crosscut by syn-to late collision granitoids related to the development of different stages of the Brasiliano Orogeny (ca. 605-480 Ma). New U-Pb (LA-ICP-MS) data of detrital zircon grains from quartzites of the top unit of the São Fidélis group yielded a large spectrum of Mesoproterozoic and Paleoproterozoic ages, with subordinated Archean and Neoproterozoic ones. The largest age peaks occur at ca. 1.2 Ga and 2.2 Ga. The youngest detrital zircon of ca. 613 Ma, and metamorphic overprints, with ages varying from ca. 602 to 570 Ma bracket the age of sedimentation of the top unit. Two orthogneisses of the Rio Negro complex intruded within the basal unit of the São Fidélis Group rendered similar ages of ca.620 Ma. These orthogneisses and the basal unit of the São Fidélis group are interpreted as possible sources of the upper unit. The provenance pattern of the São Fidélis Group is similar to that of the Kaoko Belt, suggesting that the Angolan basement, where Mesoproterozoic ages are common, constitutes another important source area.

  2. Improving orthodontic bonding to silver amalgam.

    Science.gov (United States)

    Zachrisson, B U; Büyükyilmaz, T; Zachrisson, Y O

    1995-01-01

    Flat rectangular tabs (n = 84) prepared from lathe-cut amalgam (ANA 2000) were subjected to aluminum oxide sandblasting or roughening with a diamond bur. Mandibular incisor edgewise brackets were bonded to these tabs using: Concise (Bis-GMA resin); one of three metal-bonding adhesives, viz., Superbond C&B (4-META resin), Panavia Ex (10-MDP Bis-GMA resin) or Geristore (composite base); and Concise after application of the intermediate resins All-Bond 2 Primers A+B, or the Scotch-Bond Multi-Purpose (SBMP) system. All specimens were stored in water at 37 degrees C for 24 hours before tensile bond strength testing. Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n = 12) were bonded with Concise to extracted caries-free mandibular incisors. Bond failure sites were classified by a modified ARI system. Mean tensile bond strengths in the experimental group ranged from 3.4 to 6.4 MPa--significantly weaker than the control sample (13.2 MPa). Bond failure generally occurred at the amalgam/adhesive interface. Superbond C&B created the strongest bonds to amalgam; according to ANOVA and Duncan's Multiple-Range test, they were significantly stronger than the bonds with Panavia Ex and Concise, with Geristore in between. However, the bond strength of Concise to sandblasted amalgam was comparable to the Superbond C&B bonds when coupled with an intermediate application of All-Bond 2 Primers A+B. The SBMP, on the other hand, was less effective.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Critical Heegaard surfaces obtained by amalgamation

    CERN Document Server

    Lee, Jung Hoon

    2011-01-01

    Critical surfaces are defined by Bachman as topological index 2 surfaces, generalizing incompressible surfaces and strongly irreducible surfaces. In this paper we give a condition to obtain critical Heegaard surfaces by amalgamation. As a special case, we obtain critical Heegaard surfaces by boundary stabilization. It gives critical Heegaard surfaces of non-minimal genus, for 3-manifolds which do not admit distinct Heegaard splittings (up to isotopy).

  4. Increased Release of Mercury from Dental Amalgam Fillings due to Maternal Exposure to Electromagnetic Fields as a Possible Mechanism for the High Rates of Autism in the Offspring: Introducing a Hypothesis.

    Science.gov (United States)

    Mortazavi, Gh; Haghani, M; Rastegarian, N; Zarei, S; Mortazavi, S M J

    2016-03-01

    According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields.  Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring.

  5. Increased Release of Mercury from Dental Amalgam Fillings due to Maternal Exposure to Electromagnetic Fields as a Possible Mechanism for the High Rates of Autism in the Offspring: Introducing a Hypothesis

    Science.gov (United States)

    Mortazavi, Gh.; Haghani, M.; Rastegarian, N.; Zarei, S.; Mortazavi, S.M.J.

    2016-01-01

    According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields.  Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring. PMID:27026954

  6. Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Nikhil, E-mail: nkumar.phd2011.bt@nitrr.ac.in; Upadhyay, Lata Sheo Bachan, E-mail: contactlataupadhyay@gmail.com

    2016-11-01

    Highlights: • A facile and eco-friendly method for the synthesis of L-cysteine functionalized copper nanoparticles is reported. • Synthesis of Highly stable L-cysteine functionalized copper nanoparticles (∼40 nm) was done in an aqueous medium. • FTIR analysis shows that L-cysteine bound to the nanoparticle surface via thiol group. - Abstract: A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month.

  7. DIRECT PERMANENT RESTORATIVES - AMALGAM VS COMPOSITE

    Directory of Open Access Journals (Sweden)

    Bhagyashree

    2013-11-01

    Full Text Available ABSTRACT: Dental restoration is the most commonly administered dental treatment. These restorations are subjected to dynamic conditions in oral cavity, are likely to fail and need replacement. Ideal restorative material should pass two tests - Longitivity and Esthetics. Longitivity of the restorative material depends on three major factors - first is Patient’s factors, second is Operator`s skills and last is the Restorative material itself. Dentists today have a plethora of materials to choose from. Materials like Silver Amalgam being tested over a century, other nubile but promising materials, developed recently and yet to be tested in long run. This puts a dentist in dilemma so as which material to select to ensure durable clinical p erformance after placement. Amalgam has been tested over 165 years and has fulfilled almost all desired qualities of a restorative material except esthetics. On the other hand composites have advantage in cases where esthetics is of prime importance; howev er Recent studies conclude them at par with amalgam 1 . Performance of these two materials is assessed on following criterions - Longevity, wear resistance, cost effectiveness, marginal leakage and predisposal to secondary decay, biocompatibility, pulp irri tation, tooth preparation, technique sensitivity and esthetics

  8. Recovery of silver residues from dental amalgam

    Directory of Open Access Journals (Sweden)

    Heloísa Aparecida Barbosa da Silva Pereira

    2010-04-01

    Full Text Available Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO3, followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

  9. [Microleakage of four different amalgam binding systems].

    Science.gov (United States)

    Oberholzer, T G; Grobler, S R; Rossouw, R J; van Wyk Kotze, T J; Grobler-Rabie, A

    2001-02-01

    This-study was undertaken to evaluate and compare microleakage in class V cavities in human teeth which were lined with Amalgambond Plus with HPA (Parkell, USA), Optibond Solo (Kerr, U.S.A.), Fuji Plus (GC Corporation, Japan) and Prime & Bond 2.1 (Dentsply, Switzerland), and then restored with Logic amalgam (SDI Australia). The restored teeth were thermocycled in basic fuchsin dye, sectioned, and evaluated for dye penetration. The interdiffusion zones were viewed in a confocal laser scanning microscope (CLSM). The results showed that no bonding system could totally eliminate microleakage. Statistical analysis revealed significant differences between Amalgambond Plus with HPA and Prime & Bond 2.1, Fuji Plus as well as Optibond Solo, for both the enamel and dentine sides. No significant differences were found between Prime & Bond 2.1, Fuji Plus and Optibond Solo, for both the enamel and dentine sides. Amalgambond Plus showed significantly more leakage at dentine sides while Prime & Bond 2.1 showed significantly more leakage at enamel sides. The CLSM revealed hybrid layers of different thicknesses, resin penetration into tubules, as well as resin incorporation within the spherical particles of the amalgam. Optibond Solo, Fuji Plus and Prime & Bond 2.1 can serve to improve the marginal seal of amalgam restorations.

  10. Lustrous copper nanoparticle film: Photodeposition with high quantum yield and electric conductivity

    Science.gov (United States)

    Miyagawa, Masaya; Yonemura, Mari; Tanaka, Hideki

    2016-11-01

    Cu nanoparticle (NP) film has attracted much attention due to its high electric conductivity. In the present study, we prepared a Cu NP film on a TiO2-coated substrate by photoreduction of copper acetate solution. The obtained film showed high electric conductivity and metallic luster by the successive deposition of Cu NP. Moreover, the film was decomposed on exposure to fresh air, and its decomposition reaction mechanisms were proposed. Hence, we concluded that the obtained lustrous film was composed of Cu NP, even though its physical properties was similar to bulk copper.

  11. 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.

  12. High-concentration copper nanoparticles synthesis process for screen-printing conductive paste on flexible substrate

    Science.gov (United States)

    Tam, Sze Kee; Ng, Ka Ming

    2015-12-01

    This study presents a method for the synthesis of copper nanoparticles, which are poised to replace silver nanoparticles in some application areas of printed electronics. This method offers three advantages. Firstly, copper loading in the synthesis reaction can be as high as 1 M, offering high productivity in large-scale production. Secondly, the size of the copper nanoparticles can be controlled from 12 to 99 nm. Thirdly, the surface polarity of the particles can be modified. Thus, a tailor-made product can be synthesized. The synthesis of copper nanoparticles coated with various capping agents, including dodecanethiol, lauric acid, nonanoic acid, polyacrylic acid, and polyvinyl pyrrolidone, was demonstrated. The nonanoic acid-coated copper nanoparticles were formulated as a screen-printing conductive paste. The particles were readily dispersed in terpineol, and the paste could be screen printed onto flexible polyester. The electrical resistivity of patterns after a low-temperature (120 °C) sintering treatment was around 5.8 × 10-5 Ω cm.

  13. High-concentration copper nanoparticles synthesis process for screen-printing conductive paste on flexible substrate

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Sze Kee; Ng, Ka Ming, E-mail: kekmng@ust.hk [The Hong Kong University of Science and Technology, Department of Chemical and Biomolecular Engineering (Hong Kong)

    2015-12-15

    This study presents a method for the synthesis of copper nanoparticles, which are poised to replace silver nanoparticles in some application areas of printed electronics. This method offers three advantages. Firstly, copper loading in the synthesis reaction can be as high as 1 M, offering high productivity in large-scale production. Secondly, the size of the copper nanoparticles can be controlled from 12 to 99 nm. Thirdly, the surface polarity of the particles can be modified. Thus, a tailor-made product can be synthesized. The synthesis of copper nanoparticles coated with various capping agents, including dodecanethiol, lauric acid, nonanoic acid, polyacrylic acid, and polyvinyl pyrrolidone, was demonstrated. The nonanoic acid-coated copper nanoparticles were formulated as a screen-printing conductive paste. The particles were readily dispersed in terpineol, and the paste could be screen printed onto flexible polyester. The electrical resistivity of patterns after a low-temperature (120 °C) sintering treatment was around 5.8 × 10{sup −5} Ω cm.Graphical Abstract.

  14. High-temperature conductivity in chemical bath deposited copper selenide thin films

    Science.gov (United States)

    Dhanam, M.; Manoj, P. K.; Prabhu, Rajeev. R.

    2005-07-01

    This paper reports high-temperature (305-523 K) electrical studies of chemical bath deposited copper (I) selenide (Cu 2-xSe) and copper (II) selenide (Cu 3Se 2) thin films. Cu 2-xSe and Cu 3Se 2 have been prepared on glass substrates from the same chemical bath at room temperature by controlling the pH. From X-ray diffraction (XRD) profiles, it has been found that Cu 2-xSe and Cu 3Se 2 have cubic and tetragonal structures, respectively. The composition of the chemical constituent in the films has been confirmed from XRD data and energy-dispersive X-ray analysis (EDAX). It has been found that both phases of copper selenide thin films have thermally activated conduction in the high-temperature range. In this paper we also report the variation of electrical parameters with film thickness and the applied voltage.

  15. Dynamic recrystallization of electroformed copper liners of shaped charges in high-strain-rate plastic deformation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The microstructures in the electroformed copper liners of shaped charges after high-strain-rate plastic deformation were investigated by transmission electron microscopy (TEM). Meanwhile, the orientation distribution of the grains in the recovered slug was examined by the electron backscattering Kikuchi pattern (EBSP) technique. EBSP analysis illustrated that unlike the as-formed electroformed copper linersof shaped charges the grain orientations in the recovered slug are distributed along randomly all the directions after undergoing heavily strain deformation at high-strain rate. Optical microscopy shows a typical recrystallization structure, and TEM examination reveals dislocation cells existed in the thin foil specimen. These results indicate that dynamic recovery and recrystallization occur during this plastic deformation process, and the associated deformation temperature is considered to be higher than 0.6 times the melting point of copper.

  16. Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

    Science.gov (United States)

    Kumar, Nikhil; Upadhyay, Lata Sheo Bachan

    2016-11-01

    A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month

  17. Chloride-Ion Penetrability and Mechanical Analysis of High Strength Concrete with Copper Slag

    Directory of Open Access Journals (Sweden)

    Savaş Erdem

    2014-05-01

    Full Text Available The use of waste materials and industrial by-products in high-strength concrete could increase the sustainability of the construction industry. In this study, the potential of using copper slag as coarse aggregate in high-strength concrete was experimentally investigated. The effects of replacing gravel coarse aggregate by copper slag particles on the compressive strength, chloride ion- migration, water permeability and impact resistance of high-strength concretes were evaluated. Incorporating copper slag coarse particles resulted in a compressive strength increase of about 14 % on average partly due to the low Ca/Si ratio through the interface area of this concrete (more homogenous internal structure as confirmed by the energy dispersive X-ray micro chemical analysis. It was also found that the copper slag high-strength concrete provided better ductility and had much greater load carrying capacity compared to gravel high-strength concrete under dynamic conditions. Finally, it was observed that in comparison to the high strength concrete with slag, the chloride migration coefficient from non-steady state migration was approximately 30 % greater in the gravel high-strength concrete.

  18. A technical report on repair of amalgam-dentin complex.

    Science.gov (United States)

    Ozcan, M; Salihoğlu-Yener, E

    2011-01-01

    This clinical report describes a repair protocol for cusp fracture of a failed amalgam-dentin complex. A maxillary right first premolar with an amalgam restoration presented a buccal cusp fracture. Chairside repair has been undertaken by conditioning the existing amalgam restoration with silica coating (30 μm CoJet®-Sand), phosphoric acid etching the beveled enamel surface, priming dentin, and application of a bonding agent on both enamel and dentin. Thereafter, the amalgam was silanized (ESPE®-Sil), and opaque resin was applied and polymerized to mask the amalgam. The fractured buccal cusp was modeled using resin composite (Clearfil Photo Posterior) and photo-polymerized. Finally, the amalgam was refinished and refurbished and the composite was finished and polished.

  19. Regular Semigroups Which Are Amalgamation Bases for Finite Semigroups

    Institute of Scientific and Technical Information of China (English)

    Kunitaka Shoji

    2007-01-01

    In this paper, we prove that a completely O-simple (or completely simple) semigroup is an amalgamation base for finite semigroups if and only if it is an amalgamation base for semigroups.By adopting the same method as used in a previous paper, we prove that a finite regular semigroup is an amalgamation base for finite semigroups if its Jclasses are linearly ordered and all of its principal factor semigroups are amalgamation bases for finite semigroups.Finally, we give an example of a finite semigroup U which is an amalgamation base for semigroups, but not all of its principal factor semigroups are amalgamation bases either for semigroups or for finite semigroups.

  20. METHOD AND APPARATUS FOR DETERMINING AMALGAM DECOMPOSITION RATE

    Science.gov (United States)

    Johnson, R.W.; Wright, C.C.

    1962-04-24

    A method and apparatus for measuring the rate at which an amalgam decomposes in contact with aqueous solutions are described. The amalgam and an aqueous hydroxide solution are disposed in an electrolytic cell. The amalgam is used as the cathode of the cell, and an electrode and anode are disposed in the aqueous solution. A variable source of plating potential is connected across the cell. The difference in voltage between the amalgam cathode and a calibrated source of reference potential is used to control the variable source to null the difference in voltage and at the same time to maintain the concentration of the amalgam at some predetermined constant value. The value of the current required to maintain this concentration constant is indicative of the decomposition rate of the amalgam. (AEC)

  1. Applications of copper vapor laser lighting in high-speed motion analysis

    Science.gov (United States)

    Hogan, Daniel C.

    1991-01-01

    Over the past few years copper vapor lasers have become an important tool in high speed photography as a high-tech strobe lighting source. The short flash duration ( 025 microseconds) high brightness (of the order of 20 million Lumens) and high flash rates (32 per second from a single laser 96 per second from three lasers) of copper vapor lasers have enabled high resolution analysis of processes that previously could not be explored using conventional incandescent continuous or strobe lighting sources. A summary of applications that have benefited from the use of copper laser lighting will be presented. These applications include: analysis of shock waves in turbine engine blades analysis of spinning fibers in the textile industry analysis of the bursting of high pressure storage vessels analysis of turbulent flow in internal combustion engines and capture of ballistic data of objects travelling in excess of 1500ms1(3 mph). Discussion of why copper laser lighting was crucial in each of these applications will be presented.

  2. Effect of surface roughness on amalgam repair using adhesive systems.

    Science.gov (United States)

    Giannini, Marcelo; Paulillo, Luis Alexandre Maffei Sartini; Ambrosano, Gláucia Maria Bovi

    2002-01-01

    The objective of this in vitro study was to evaluate the effect of three surface treatments and two adhesive systems on the shear bond strength of old and freshly placed amalgam. The results suggested that the intact amalgam showed a significantly higher strength than repaired groups and the strongest repaired specimens were made when the amalgam surfaces were roughened with a diamond bur or microetcher. The adhesive systems showed no significant differences on bond strength with the same superficial texture.

  3. Fracture resistance of teeth restored with the bonded amalgam technique.

    Science.gov (United States)

    Dias de Souza, G M; Pereira, G D; Dias, C T; Paulillo, L A

    2001-01-01

    This study evaluated the fracture resistance of maxillary premolars with MOD Class II cavity preparations restored with silver amalgam (G1), Scotchbond Multi Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After the restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test. Statistical analysis of the data (ANOVA and Tukey Test) revealed no significant differences among the three groups that were studied.

  4. Recirculation of Chilean copper smelting dust with high impurities contents to the smelting process

    Energy Technology Data Exchange (ETDEWEB)

    Sano, H.; Fujisawa, T. [Nagoya Univ., Nagoya (Japan). EcoTopia Science Inst.; Montenegro, V. [Nagoya Univ., Nagoya (Japan). Dept. of Materials Science and Engineering

    2007-07-01

    Dust generated during the copper smelting process is generally stabilized using hydrometallurgical methods as it contains high concentrations of arsenic. In this laboratory study, dust was recirculated during the smelting process in order to recover more copper and decrease dust emissions while recovering more copper. The behaviour of impurities and their influence on matte quality was also investigated. Industrial matte, flue dust, slag, and copper concentrates from a Chilean smelter were used as test materials. Dust recirculation tests were conducted in a simulated electric furnace. Off-gases were collected in a reaction tube, and the condensed volatile matter, slag, and matte phases were analyzed for their elemental content by inductively coupled plasma atomic emission spectrometry. The distribution of arsenic (As); antimony (Sb), bismuth (Bi), lead (Pb), and zinc (Zn) were investigated by varying the amounts of dust recirculating to the smelting stage with 21 per cent of the oxygen. Results showed that distributions of all analyzed elements increased with recirculation. It was concluded that copper can be recovered using the dust recirculation technique. However, impurities may limit the efficacy of the dust recirculation process. 6 refs., 3 tabs., 4 figs.

  5. Copper-phthalocyanine encapsulated into zeolite-Y with high Si/Al: An EPR study

    Science.gov (United States)

    Yahiro, Hidenori; Kimoto, Kunihiro; Yamaura, Hiroyuki; Komaguchi, Kenji; Lund, Anders

    2005-10-01

    Copper (II) phthalocyanine (CuPc) molecules encapsulated into zeolite-Y with Si/Al ratios of 2.7 and 410 were prepared by an in situ synthesis and characterized by UV-Vis and electron paramagnetic resonance (EPR) spectroscopies. Resolved Cu-hyperfine and N-superhyperfine structures were observed in the EPR spectrum of CuPc encapsulated into zeolite-Y with a high Si/Al ratio. UV-Vis and EPR studies as well as theoretical calculations suggest that the encapsulated CuPc molecule was distorted in zeolite-Y with keeping of the square-planar symmetry around the center copper (II) ion.

  6. Copper-Based Ultrathin Nickel Nanocone Films with High-Efficiency Dropwise Condensation Heat Transfer Performance.

    Science.gov (United States)

    Zhao, Ye; Luo, Yuting; Zhu, Jie; Li, Juan; Gao, Xuefeng

    2015-06-10

    We report a type of copper-based ultrathin nickel nanocone films with high-efficiency dropwise condensation heat transfer (DCHT) performance, which can be fabricated by facile electrodeposition and low-surface-energy chemistry modification. Compared with flat copper samples, our nanosamples show condensate microdrop self-propelling (CMDSP) function and over 89% enhancement in the DCHT coefficient. Such remarkable enhancement may be ascribed to the cooperation of surface nanostructure-induced CMDSP function as well as in situ integration and ultrathin nature of nanofilms. These findings are very significant to design and develop advanced DCHT materials and devices, which help improve the efficiency of thermal management and energy utilization.

  7. High temperature tension-compression fatigue behavior of a tungsten copper composite

    Science.gov (United States)

    Verrilli, Michael J.; Gabb, Timothy P.

    1990-01-01

    The high temperature fatigue of a (O)12 tungsten fiber reinforced copper matrix composite was investigated. Specimens having fiber volume percentages of 10 and 36 were fatigued under fully-reversed, strain-controlled conditions at both 260 and 560 C. The fatigue life was found to be independent of fiber volume fraction because fatigue damage preferentially occurred in the matrix. Also, the composite fatigue lives were shorter at 560 C as compared to 260 C due to changes in mode of matrix failure. On a total strain basis, the fatigue life of the composite at 560 C was the same as the life of unreinforced copper, indicating that the presence of the fibers did not degrade the fatigue resistance of the copper matrix in this composite system. Comparison of strain-controlled fatigue data to previously-generated load-controlled data revealed that the strain-controlled fatigue lives were longer because of mean strain and mean stress effects.

  8. High Strain-Rate Mechanical Behaviour of a Copper Matrix Composite for Nuclear Applications

    CERN Document Server

    Peroni, L

    2012-01-01

    Aim of this work is the investigation of mechanical behaviour of an alumina dispersion strengthened copper, known by the trade name GLIDCOP®, subjected to dynamic loads: it is a composite material with a copper matrix strengthened with aluminium oxide ceramic particles. Since the particle content is quite small the material keeps the OFE copper physical properties, such as thermal and electrical conductivity, but with a higher yield strength, like a mild-carbon steel. Besides, with the addition of aluminium oxide, the good mechanical properties are retained also at high temperatures and the resistance to thermal softening is increased: the second phase blocks the dislocation movement preventing the grain growth. Thanks to these properties GLIDCOP® finds several applications in particle accelerator technologies, where problems of thermal management, combined with structural requirements, play a key role. Currently, it is used for the construction of structural and functional parts of the particle beam collim...

  9. Survival of ART and amalgam restorations in permanent teeth of children after 6.3 years.

    NARCIS (Netherlands)

    Frencken, J.E.F.M.; Taifour, D.; Hof, M.A. van 't

    2006-01-01

    The null hypothesis tested was that there is no difference in the survival percentages of all restorations placed through the Atraumatic Restorative Treatment (ART) approach, with high-viscosity glass ionomer, and those produced through the traditional approach, with amalgam (TA), in the permanent d

  10. Highly cytotoxic DNA-interacting copper(II) coordination compounds.

    Science.gov (United States)

    Brissos, Rosa F; Torrents, Ester; dos Santos Mello, Francyelli Mariana; Carvalho Pires, Wanessa; Silveira-Lacerda, Elisângela de Paula; Caballero, Ana B; Caubet, Amparo; Massera, Chiara; Roubeau, Olivier; Teat, Simon J; Gamez, Patrick

    2014-10-01

    Four new Schiff-base ligands have been designed and prepared by condensation reaction between hydrazine derivatives (i.e. 2-hydrazinopyridine or 2-hydrazinoquinoline) and mono- or dialdehyde (3-tert-butyl-2-hydroxybenzaldehyde and 5-tert-butyl-2-hydroxyisophthalaldehyde, respectively). Six copper(II) coordination compounds of various nuclearities have been obtained from these ligands, which are formulated as [Cu(L1)Cl](CH3OH) (1), [Cu(L2)NO3] (2), [Cu2(L3)(ClO4)2(CH3O)(CH3OH)](CH3OH) (3), [Cu2(L4)(ClO4)(OH)(CH3OH)](ClO4) (4), [Cu8(L3)4(NO3)4(OH)5](NO3)3(CH3OH)5(H2O)8 (5) and [Cu3(HL2')4Cl6](CH3OH)6 (6), as revealed by single-crystal X-ray studies. Their DNA-interacting abilities have been investigated using different characterization techniques, which suggest that the metal complexes act as efficient DNA binders. Moreover, cytotoxicity assays with several cancer cell lines show that some of them are very active, as evidenced by the sub-micromolar IC50 values achieved in some cases.

  11. The comparative evaluation of fracture resistance and microleakage in bonded amalgam, amalgam, and composite resins in primary molars

    OpenAIRE

    H S Vanishree; B M Shanthala; W Bobby

    2015-01-01

    Background : The intense development of adhesive restorative materials and parents′ preferences for esthetic restorations prompt clinicians to use alternative restorative materials for primary molars. Amalgam, however, is the choice of material when it comes to occlusal stress bearing areas, either in primary or permanent molars. To overcome the drawbacks of amalgam and restorative adhesive materials, the bonded amalgam technique is employed. Aims: To evaluate microleakage and fracture re...

  12. High-adhesion Cu patterns fabricated by nanosecond laser modification and electroless copper plating

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Ming; Liu, Jianguo, E-mail: liujg@mail.hust.edu.cn; Zeng, Xiaoyan; Du, Qifeng; Ai, Jun

    2015-10-30

    Highlights: • High-adhesion copper patterns on alumina ceramic were obtained conveniently. • Effects of processing parameters on adhesion were investigated. • The adhesion of copper–ceramic was higher than the tensile strength of tin-lead solder. • Failure mechanism was studied by the analysis of fracture surfaces. - Abstract: Adhesion strength is a crucial factor for the performance and reliability of metallic patterns on insulator substrates. In this study, we present an efficient technique for selective metallization of alumina ceramic with high adhesion strength by using nanosecond laser modification and electroless copper plating. Specifically, a 355 nm Nd:YVO{sub 4} ultraviolet (UV) laser was employed not only to decompose palladium chloride film locally for catalyzing the electroless reaction, but also to modify the ceramic surface directly using its high fluence. An orthogonal experiment was undertaken to study the effects of processing parameters including laser fluence, scanning speed and scanning line interval on adhesion strength. The adhesion strength was measured by pulling a metallic wire soldered into the copper coating perpendicular to the substrate using a pull tester. The results have shown that a strong adhesion between the copper coating and the alumina ceramic, higher than the tensile strength of tin-lead solder was obtained. Surface and interface characteristics were investigated to understand that, whose results have shown that the high-aspect-ratio microstructures formed by the laser modification is the major reason for the improvement of adhesion.

  13. Experimental Consequences of Mottness in High-Temperature Copper-Oxide Superconductors

    Science.gov (United States)

    Chakraborty, Shiladitya

    2009-01-01

    It has been more than two decades since the copper-oxide high temperature superconductors were discovered. However, building a satisfactory theoretical framework to study these compounds still remains one of the major challenges in condensed matter physics. In addition to the mechanism of superconductivity, understanding the properties of the…

  14. High Temperature Flue Gas Desulfurization In Moving Beds With Regenerable Copper Based Sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Cengiz, P.A.; Ho, K.K.; Abbasian, J.; Lau, F.S.

    2002-09-20

    The objective of this study was to develop new and improved regenerable copper based sorbent for high temperature flue gas desulfurization in a moving bed application. The targeted areas of sorbent improvement included higher effective capacity, strength and long-term durability for improved process control and economic utilization of the sorbent.

  15. High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film

    Science.gov (United States)

    Primo, Ana; Esteve-Adell, Ivan; Blandez, Juan F.; Dhakshinamoorthy, Amarajothi; Álvaro, Mercedes; Candu, Natalia; Coman, Simona M.; Parvulescu, Vasile I.; García, Hermenegildo

    2015-10-01

    Metal oxide nanoparticles supported on graphene exhibit high catalytic activity for oxidation, reduction and coupling reactions. Here we show that pyrolysis at 900 °C under inert atmosphere of copper(II) nitrate embedded in chitosan films affords 1.1.1 facet-oriented copper nanoplatelets supported on few-layered graphene. Oriented (1.1.1) copper nanoplatelets on graphene undergo spontaneous oxidation to render oriented (2.0.0) copper(I) oxide nanoplatelets on few-layered graphene. These films containing oriented copper(I) oxide exhibit as catalyst turnover numbers that can be three orders of magnitude higher for the Ullmann-type coupling, dehydrogenative coupling of dimethylphenylsilane with n-butanol and C-N cross-coupling than those of analogous unoriented graphene-supported copper(I) oxide nanoplatelets.

  16. Spherulitic copper-copper oxide nanostructure-based highly sensitive nonenzymatic glucose sensor.

    Science.gov (United States)

    Das, Gautam; Tran, Thao Quynh Ngan; Yoon, Hyon Hee

    2015-01-01

    In this work, three different spherulitic nanostructures Cu-CuOA, Cu-CuOB, and Cu-CuOC were synthesized in water-in-oil microemulsions by varying the surfactant concentration (30 mM, 40 mM, and 50 mM, respectively). The structural and morphological characteristics of the Cu-CuO nanostructures were investigated by ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy techniques. The synthesized nanostructures were deposited on multiwalled carbon nanotube (MWCNT)-modified indium tin oxide (ITO) electrodes to fabricate a nonenzymatic highly sensitive amperometric glucose sensor. The performance of the ITO/MWCNT/Cu-CuO electrodes in the glucose assay was examined by cyclic voltammetry and chronoamperometric studies. The sensitivity of the sensor varied with the spherulite type; Cu-CuOA, Cu-CuOB, and Cu-CuOC exhibited a sensitivity of 1,229, 3,012, and 3,642 µA mM(-1)·cm(-2), respectively. Moreover, the linear range is dependent on the structure types: 0.023-0.29 mM, 0.07-0.8 mM, and 0.023-0.34 mM for Cu-CuOA, Cu-CuOB, and Cu-CuOC, respectively. An excellent response time of 3 seconds and a low detection limit of 2 µM were observed for Cu-CuOB at an applied potential of +0.34 V. In addition, this electrode was found to be resistant to interference by common interfering agents such as urea, cystamine, L-ascorbic acid, and creatinine. The high performance of the Cu-CuO spherulites with nanowire-to-nanorod outgrowths was primarily due to the high surface area and stability, and good three-dimensional structure. Furthermore, the ITO/MWCNT/Cu-CuOB electrode applied to real urine and serum sample showed satisfactory performance.

  17. Dental devices: classification of dental amalgam, reclassification of dental mercury, designation of special controls for dental amalgam, mercury, and amalgam alloy; technical amendment. Final rule; technical amendment.

    Science.gov (United States)

    2010-06-11

    The Food and Drug Administration (FDA) published a final rule in the Federal Register of August 4, 2009 (74 FR 38686) which classified dental amalgam as a class II device, reclassified dental mercury from class I to class II, and designated special controls for dental amalgam, mercury, and amalgam alloy. The effective date of the rule was November 2, 2009. The final rule was published with an inadvertent error in the codified section. This document corrects that error. This action is being taken to ensure the accuracy of the agency's regulations.

  18. [Structure-functional organization of eukaryotic high-affinity copper importer CTR1 determines its ability to transport copper, silver and cisplatin].

    Science.gov (United States)

    Skvortsov, A N; Zatulovskiĭ, E A; Puchkova, L V

    2012-01-01

    It was shown recently, that high affinity Cu(I) importer eukaryotic protein CTR1 can also transport in vitro abiogenic Ag(I) ions and anticancer drug cisplatin. At present there is no rational explanation how CTR1 can transfer platinum group, which is different by coordination properties from highly similar Cu(I) and Ag(I). To understand this phenomenon we analyzed 25 sequences of chordate CTR1 proteins, and found out conserved patterns of organization of N-terminal extracellular part of CTR1 which correspond to initial metal binding. Extracellular copper-binding motifs were qualified by their coordination properties. It was shown that relative position of Met- and His-rich copper-binding motifs in CTR1 predisposes the extracellular CTR1 part to binding of copper, silver and cisplatin. Relation between tissue-specific expression of CTR1 gene, steady-state copper concentration, and silver and platinum accumulation in organs of mice in vivo was analyzed. Significant positive but incomplete correlation exists between these variables. Basing on structural and functional peculiarities of N-terminal part of CTR1 a hypothesis of coupled transport of copper and cisplatin has been suggested, which avoids the disagreement between CTR1-mediated cisplatin transport in vitro, and irreversible binding of platinum to Met-rich peptides.

  19. Amalgam stained dentin: a proper substrate for bonding resin composite?

    NARCIS (Netherlands)

    Scholtanus, J.D.

    2016-01-01

    Nowadays the use of dental amalgam is mostly abandoned and substituted by tooth colored resin composites that can be bonded to teeth tissues by adhesive techniques. The aim of this thesis was to find out whether dark stained dentin, as often observed after removal of amalgam restorations and attribu

  20. 12-year survival of composite vs. amalgam restorations.

    NARCIS (Netherlands)

    Opdam, N.J.M.; Bronkhorst, E.M.; Loomans, B.A.C.; Huysmans, M.C.D.N.J.M.

    2010-01-01

    Information about the long-term clinical survival of large amalgam and composite restorations is still lacking. This retrospective study compares the longevity of three- and four-/five-surface amalgam and composite restorations relative to patients' caries risk. Patient records from a general practi

  1. Amalgam stained dentin: a proper substrate for bonding resin composite?

    NARCIS (Netherlands)

    Scholtanus, J.D.

    2016-01-01

    Nowadays the use of dental amalgam is mostly abandoned and substituted by tooth colored resin composites that can be bonded to teeth tissues by adhesive techniques. The aim of this thesis was to find out whether dark stained dentin, as often observed after removal of amalgam restorations and

  2. Real-Time Plasmonic Monitoring of Single Gold Amalgam Nanoalloy Electrochemical Formation and Stripping.

    Science.gov (United States)

    Wang, Jun-Gang; Fossey, John S; Li, Meng; Xie, Tao; Long, Yi-Tao

    2016-03-01

    Direct electrodeposition of mercury onto gold nanorods on an ITO substrate, without reducing agents, is reported. The growth of single gold amalgam nanoalloy particles and subsequent stripping was monitored in real-time monitoring by plasmonic effects and single-nanoparticle dark-field spectroelectrochemistry techniques. Time-dependent scattering spectral information conferred insight into the growth and stripping mechanism of a single nanoalloy particle. Four critical stages were observed: First, rapid deposition of Hg atoms onto Au nanorods; second, slow diffusion of Hg atoms into Au nanorods; third, prompt stripping of Hg atoms from Au nanorods; fourth, moderate diffusion from the inner core of Au nanorods. Under high Hg(2+) concentrations, homogeneous spherical gold amalgam nanoalloys were obtained. These results demonstrate that the morphology and composition of individual gold amalgam nanoalloys can be precisely regulated electrochemically. Moreover, gold amalgam nanoalloys with intriguing optical properties, such as modulated plasmonic lifetimes and quality factor Q, could be obtained. This may offer opportunities to extend applications in photovoltaic energy conversion and chemical sensing.

  3. Colorimetric Signal Amplification Assay for Mercury Ions Based on the Catalysis of Gold Amalgam.

    Science.gov (United States)

    Chen, Zhengbo; Zhang, Chenmeng; Gao, Qinggang; Wang, Guo; Tan, Lulu; Liao, Qing

    2015-11-03

    Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully.

  4. High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.

    Science.gov (United States)

    Lauterborn, W; Judt, A; Schmitz, E

    1993-01-01

    A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

  5. A Study of the Surface Quality of High Purity Copper after Heat Treatment

    CERN Document Server

    Aicheler, M; Atieh, S; Calatroni, S; Riddone, G; Lebet, S; Samoshkin, A

    2011-01-01

    Themanufacturing flow of accelerating structures for the compact linear collider, based on diamond-machined high purity copper components, include several thermal cycles (diffusion bonding, brazing of cooling circuits, baking in vacuum, etc.). The high temperature cycles may be carried out following different schedules and environments (vacuum, reducing hydrogen atmosphere, argon, etc.) and develop peculiar surface topographies which have been the object of extended observations. This study presents and discusses the results of scanning electron microscopy (SEM) and optical microscopy investigations.

  6. Dental devices: classification of dental amalgam, reclassification of dental mercury, designation of special controls for dental amalgam, mercury, and amalgam alloy. Final rule.

    Science.gov (United States)

    2009-08-01

    The Food and Drug Administration (FDA) is issuing a final rule classifying dental amalgam into class II, reclassifying dental mercury from class I to class II, and designating a special control to support the class II classifications of these two devices, as well as the current class II classification of amalgam alloy. The three devices are now classified in a single regulation. The special control for the devices is a guidance document entitled, "Class II Special Controls Guidance Document: Dental Amalgam, Mercury, and Amalgam Alloy." This action is being taken to establish sufficient regulatory controls to provide reasonable assurance of the safety and effectiveness of these devices. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for the devices.

  7. Enlightening the Mechanism of Copper Mediated PhotoRDRP via High-Resolution Mass Spectrometry.

    Science.gov (United States)

    Frick, Elena; Anastasaki, Athina; Haddleton, David M; Barner-Kowollik, Christopher

    2015-06-03

    The initiation mechanism of photochemically mediated Cu-based reversible-deactivation radical polymerization (photoRDRP) was investigated using pulsed-laser polymerization (PLP) and high-resolution mass spectrometry. The variation of the catalyst composition and ESI-MS analysis of the resulting products provided information on how initiator, ligand, copper species, and monomer are interacting upon irradiation with UV light. A discussion of the results allows for a new postulation of the mechanism of photoRDRP and-for the first time-the unambiguous identification of the initiating species and their interactions within the reaction mixture. One pathway for radical generation proceeds via UV light-induced C-Br bond scission of the initiator, giving rise to propagating radicals. The generation of copper(I) species from copper(II) can occur via several pathways, including, among others, via reduction by free amine ligand in its excited as well as from its ground state via the irradiation with UV light. The amine ligand serves as a strong reducing agent and is likely the main participant in the generation of copper(I) species.

  8. "A Future Amalgamation Between the Scientist and the Clinician?"

    Science.gov (United States)

    Haywood-Small, Sarah

    2017-01-01

    Personalized medicine is gaining momentum and analytical methods such as MS are ideally situated to provide coherent imaging of human disease. The cancer research field is already starting to benefit from the MS imaging applications; non-cancerous diseases will hopefully enjoy the same success. Often, the way forward is to embrace several techniques, which can complement and verify each other. This approach can be seen as less confrontational as everyone can play a part in the development of a new working practice. Stakeholders, professional bodies, and instrument manufacturers will be open to maximizing the patient benefit; investment is more likely given the past performance and reputation of the collaborative highly skilled team.With this in mind, how close are we to a future amalgamation between the scientist and the clinician? Can we accelerate the integration of innovative bench technologies into the clinical setting and bring state-of-the-art imaging diagnostics to the patient bedside or General Practitioners treatment room?

  9. The Post-Amalgam Era: Norwegian Dentists' Experiences with Composite Resins and Repair of Defective Amalgam Restorations.

    Science.gov (United States)

    Kopperud, Simen E; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-04-22

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists' satisfaction with alternative restorative materials and to explore dentists' treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p amalgam restorations.

  10. High Dietary Copper Increases Catecholamine Concentrations in the Hypothalami and Midbrains of Growing Pigs.

    Science.gov (United States)

    Yang, Wenyan; Zhao, Chunyu; Zhang, Cai; Yang, Lianyu

    2016-03-01

    The experiment was conducted to investigate the effect of high dietary copper on catecholamine concentration and dopamine-β-hydroxylase (DβH) activity in hypothalami and midbrains of growing pigs. Forty-five crossbred weanling pigs with an average body weight of 7.5 kg were randomly assigned to three groups of 15 each to receive a control diet containing 10 mg/kg Cu (diet A) and diets containing 125 (diet B) or 250 (diet C) mg Cu/kg DM for 45 days. Compared to the control, Cu supplementation at both 125 and 250 mg Cu/kg DM increased average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency. High dietary copper increased midbrain and hypothalami dopamine (DA) and norepinephrine (NE) concentrations and midbrain dopamine-β-hydroxylase activity. However, increasing dietary Cu had no effect on hypothalami dopamine-β-hydroxylase activity.

  11. The Effect of Tool Position for Aluminum and Copper at High Rotational Friction Stir Welding

    OpenAIRE

    Recep Çakır; Sare Çelik

    2015-01-01

    Friction Stir Welding (FSW) is a solid state welding process used for welding similar and dissimilar materials. This welding technique allows welding of Aluminum alloys which present difficulties in fusion joining and allows different material couples to be welded continuously. In this study, 1050 aluminum alloy and commercially pure copper to increase heat input were produced at high rotation rate (2440 rev/min) with four different pin position (0-1-1.5-2 mm) and three different weld speeds ...

  12. High-voltage electrical burns due to copper theft - Case series.

    Science.gov (United States)

    Braga, M J; Oliveira, I; Egipto, P; Silva, A

    2016-03-31

    Electrical burns are among the most devastating trauma inflicted on the human body. These burns have a higher morbidity, length of stay and a much higher risk of amputation than any other type of burn. Electrical burns affect mostly young, working males because they are more frequently the result of a work accident. However, possibly due to the worldwide economic crisis, we are experiencing a new phenomenon: the theft of high-voltage copper wiring.

  13. High-voltage electrical burns due to copper theft – Case series

    Science.gov (United States)

    Braga, M.J.; Oliveira, I.; Egipto, P.; Silva, A.

    2016-01-01

    Summary Electrical burns are among the most devastating trauma inflicted on the human body. These burns have a higher morbidity, length of stay and a much higher risk of amputation than any other type of burn. Electrical burns affect mostly young, working males because they are more frequently the result of a work accident. However, possibly due to the worldwide economic crisis, we are experiencing a new phenomenon: the theft of high-voltage copper wiring. PMID:27857650

  14. Embrittlement of low copper VVER 440 surveillance samples neutron-irradiated to high fluences

    Science.gov (United States)

    Miller, M. K.; Russell, K. F.; Kocik, J.; Keilova, E.

    2000-11-01

    An atom probe tomography microstructural characterization of low copper (0.06 at.% Cu) surveillance samples from a VVER 440 reactor has revealed manganese and silicon segregation to dislocations and other ultrafine features in neutron-irradiated base and weld materials (fluences 1×10 25 m-2 and 5×10 24 m-2, E>0.5 MeV, respectively). The results indicate that there is an additional mechanism of embrittlement during neutron irradiation that manifests itself at high fluences.

  15. The dental amalgam toxicity fear: a myth or actuality.

    Science.gov (United States)

    Rathore, Monika; Singh, Archana; Pant, Vandana A

    2012-05-01

    Amalgam has been used in dentistry since about 150 years and is still being used due to its low cost, ease of application, strength, durability, and bacteriostatic effect. When aesthetics is not a concern it can be used in individuals of all ages, in stress bearing areas, foundation for cast-metal and ceramic restorations and poor oral hygiene conditions. Besides all, it has other advantages like if placed under ideal conditions, it is more durable and long lasting and least technique sensitive of all restorative materials, but, concern has been raised that amalgam causes mercury toxicity. Mercury is found in the earth's crust and is ubiquitous in the environment, so even without amalgam restorations everyone is exposed to small but measurable amount of mercury in blood and urine. Dental amalgam restorations may raise these levels slightly, but this has no practical or clinical significance. The main exposure to mercury from dental amalgam occurs during placement or removal of restoration in the tooth. Once the reaction is complete less amount of mercury is released, and that is far below the current health standard. Though amalgam is capable of producing delayed hypersensitivity reactions in some individuals, if the recommended mercury hygiene procedures are followed the risks of adverse health effects could be minimized. For this review the electronic databases and PubMed were used as data sources and have been evaluated to produce the facts regarding amalgam's safety and toxicity.

  16. Copper hexacyanoferrate battery electrodes with long cycle life and high power

    KAUST Repository

    Wessells, Colin D.

    2011-11-22

    Short-term transients, including those related to wind and solar sources, present challenges to the electrical grid. Stationary energy storage systems that can operate for many cycles, at high power, with high round-trip energy efficiency, and at low cost are required. Existing energy storage technologies cannot satisfy these requirements. Here we show that crystalline nanoparticles of copper hexacyanoferrate, which has an ultra-low strain open framework structure, can be operated as a battery electrode in inexpensive aqueous electrolytes. After 40,000 deep discharge cycles at a 17g-C rate, 83% of the original capacity of copper hexacyanoferrate is retained. Even at a very high cycling rate of 83g-C, two thirds of its maximum discharge capacity is observed. At modest current densities, round-trip energy efficiencies of 99% can be achieved. The low-cost, scalable, room-temperature co-precipitation synthesis and excellent electrode performance of copper hexacyanoferrate make it attractive for large-scale energy storage systems. © 2011 Macmillan Publishers Limited. All rights reserved.

  17. [Black or white--Which choice for the molars? Part 2. Which does one choose for the restoration of posterior teeth: amalgam or composite?].

    Science.gov (United States)

    De Moor, Roeland; Delmé, Katleen

    2008-01-01

    The two direct dental restorative materials most commonly used today are silver-mercury amalgam and resin-based composite. The survival of dental amalgam restorations is twice as high than for composite fillings: polymerisation shrinkage, deficient marginal adaptation, higher wear rates, defective contact points leading to food impaction, insufficiently converted composite at the bottom of the cavity are problems that cannot be underestimated when using resin-composite. This does not imply that there is no weakness for amalgam: the need for retentive cavities at the cost of healthy tooth substance, weakening of the tooth's strength by cutting through the tooth crown's ridges, the risk of fracture of remaining tooth substance (mostly buccal and lingual surfaces) as the result of the cavity design, and the lack of adhesion between amalgam and tooth substance. Retaining a tooth's strength by the replacement of amalgam by resin-composites is not always the correct solution. In this respect, it can be questioned whether it is not appropriate to repair failing (extensive) amalgam restorations as to replace them with resin-composites. Research in this respect has demonstrated that dentists still are not convinced of this treatment option. Restoring a tooth in its original build-up or structure and function within the oral cavity is the basis of the biomimetic principle: the use of composite appears to be more obvious than restoring with amalgam. In the present survey pro's and con's of amalgams and resin-composites for the restoration of posterior teeth are weighted. The conclusion demonstrates that there is still a place for dental amalgam in modern restorative dentistry when plastic filling materials are used for the direct tooth repair or restoration.

  18. 75 FR 33169 - Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation...

    Science.gov (United States)

    2010-06-11

    ...-AG21 Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation of Special Controls for Dental Amalgam, Mercury, and Amalgam Alloy; Technical Amendment AGENCY: Food... classified dental amalgam as a class II device, reclassified dental mercury from class I to class II, and...

  19. Large-grained copper indium diselenide crystal growth by computer-controlled high-pressure liquid-encapsulated directional solidification

    Science.gov (United States)

    Schwerdtfeger, C. R.; Ciszek, T. F.

    1992-12-01

    Large-grained copper indium diselenide crystal growth by computer-controlled high-pressure liquid-encapsulated directional solidification is presented. A supply of good quality angle crystals is essential to characterization of the fundamental material properties. [AIP

  20. A promising structure for fabricating high strength and high electrical conductivity copper alloys.

    Science.gov (United States)

    Li, Rengeng; Kang, Huijun; Chen, Zongning; Fan, Guohua; Zou, Cunlei; Wang, Wei; Zhang, Shaojian; Lu, Yiping; Jie, Jinchuan; Cao, Zhiqiang; Li, Tingju; Wang, Tongmin

    2016-02-09

    To address the trade-off between strength and electrical conductivity, we propose a strategy: introducing precipitated particles into a structure composed of deformation twins. A Cu-0.3%Zr alloy was designed to verify our strategy. Zirconium was dissolved into a copper matrix by solution treatment prior to cryorolling and precipitated in the form of Cu5Zr from copper matrix via a subsequent aging treatment. The microstructure evolutions of the processed samples were investigated by transmission electron microscopy and X-ray diffraction analysis, and the mechanical and physical behaviours were evaluated through tensile and electrical conductivity tests. The results demonstrated that superior tensile strength (602.04 MPa) and electrical conductivity (81.4% IACS) was achieved. This strategy provides a new route for balancing the strength and electrical conductivity of copper alloys, which can be developed for large-scale industrial application.

  1. High resistance to sulfur poisoning of Ni with copper skin under electric field

    Science.gov (United States)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2017-02-01

    The effects of sulfur poisoning on the (1 0 0), (1 1 0) and (1 1 1) surfaces of pure Ni and Cu/Ni alloy are studied in consideration of the effect of electric field. The effects of Cu dopants on the S poisoning characteristics are analyzed by the means of the density functional theory results in combination with thermodynamics data using the ab initio atomistic thermodynamic method. When the Cu concentration increases to 50% on the surface layer of the Cu/Ni alloy, the (1 1 0) surface becomes the most vulnerable to the sulfur poisoning. Ni with a copper skin can mostly decrease the sulfur poisoning effect. Especially under the electric field of 1.0 V/Å, the sulfur adsorption and phase transition temperature can be further reduced. We therefore propose that Ni surfaces with copper skin can be very effective to improve the resistance to sulfur poisoning of the Ni anode under high electric field.

  2. Reliable Copper and Aluminum Connections for High Power Applications in Electromobility

    Science.gov (United States)

    Hofmann, Konstantin; Holzer, Matthias; Hugger, Florian; Roth, Stephan; Schmidt, Michael

    Investigations concerning the growth of intermetallic phases during the heat input both at the diffusion annealing of copper aluminum roll claddings and the subsequent welding process of copper-aluminum connections by using roll cladded inserts are compared to the analytical determination of phase growth. The temperature distribution in the cladding interface has been determined by thermal simulation, in order to calculate the growth of the intermetallic phases. A comparison between the width of the phases in the analytical calculation and the experiment is achieved. In consideration of high welding speeds, the energy input during the welding process is appraised in order to grade the growth of intermetallic phases. Furthermore the prevention of damage in the roll cladding interface by means of unadapted material thicknesses or welding parameters can be assessed analytically and numerically. The numerical simulations can determine the critical thickness of the roll cladding to avoid damage like exceeding growth of intermetallic phases.

  3. Evaluation of various concentrations of alkaline surface treatment on interfacial bond strengths of amalgam bonded to amalgam.

    Science.gov (United States)

    Mirza, Asaad Javaid; Ahmad, Asif; Mohammad, Taqi; Khan, Zahid Akhter

    2013-09-01

    This study was done to assess the influence of alkaline surface modification on interfacial bond strength of existing fractured (old) amalgam restoration bonded to fresh amalgam. Old and Fresh amalgam interfaced samples were prepared by applying a 4-methacryloyloxyethy trimellitate anhydride (4-META) containing adhesive. The adhesive used was Amalgabond (Parkell, Farmingdale, NY 11735, USA). Four concentrations of calcium hydroxide Ca(OH)2 solutions were used as a surface modifiers for old amalgam to increase the pH of the amalgam surfaces. The concentrations used were 2.5, 5, 10 and 15%. Direct measurement of the interfacial bond strength was carried out using an electromechanical universal tensile testing machine at crosshead speed of 10mm per minute. Results show that all the calcium hydroxide modified samples produced the increased tensile bond strength (TBS) as compared to their control group. The highest values of bond strength were achieved using 15% Ca(OH)2 solution as surface modifier. Pretreatment of fractured amalgam with calcium hydroxide improves the bond strength of 4-META adhesives. Its use in repair of amalgam may therefore be considered.

  4. Electrochemical synthesis of highly ordered polypyrrole on copper modified aluminium substrates

    Energy Technology Data Exchange (ETDEWEB)

    Siddaramanna, Ashoka [Centre Universitaire de Recherche sur l’Aluminium, University of Quebec at Chicoutimi, Saguenay, Quebec G7H2B1 (Canada); Saleema, N. [Aluminum Technology Centre, National Research Council of Canada, University East, Saguenay, Quebec G7H8C3 (Canada); Sarkar, D.K., E-mail: dsarkar@uqac.ca [Centre Universitaire de Recherche sur l’Aluminium, University of Quebec at Chicoutimi, Saguenay, Quebec G7H2B1 (Canada)

    2014-07-01

    Fabrication of highly ordered conducting polymers on metal surfaces has received a significant interest owing to their potential applications in organic electronic devices. In this context, we have developed a simple method for the synthesis of highly ordered polypyrrole (PPy) on copper modified aluminium surfaces via electrochemical polymerization process. A series of characteristic peaks of PPy evidenced on the infrared spectra of these surfaces confirm the formation of PPy. The X-ray diffraction (XRD) pattern of PPy deposited on copper modified aluminium surfaces also confirmed the deposition of PPy as a sharp and intense peak at 2θ angle of 23° attributable to PPy is observed while this peak is absent on PPy deposited on as-received aluminium surfaces. An atomic model of the interface of PPy/Cu has been presented based on the inter-atomic distance of copper–copper of (1 0 0) plane and the inter-monomer distance of PPy, to describe the ordering of PPy on Cu modified Al surfaces.

  5. Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils

    DEFF Research Database (Denmark)

    Christiansen, Karen Søgaard; Borggaard, Ole K.; Holm, Peter Engelund

    2015-01-01

    Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils...

  6. Effects of mercury release from amalgam dental restorations during cremation on soil mercury levels of three New Zealand crematoria

    Energy Technology Data Exchange (ETDEWEB)

    Nieschmidt, A.K.; Kim, N.D. [Univ. of Waikato, Hamilton (New Zealand)

    1997-05-01

    A vast amount of research has been undertaken in the last 15-20 years on the corrosion reactions occurring in dental amalgam, release of mercury from amalgam restorations, and the toxic effects of this released mercury on the human body. However, one environmental aspect of amalgam dental restorations that has not received a great deal of attention is the release of mercury during cremation. Mercury is liberated during cremation both because dental amalgams are unstable at cremation temperatures (650-700{degrees}C) and because the free mercury metal is highly volatile. In New Zealand, 58% of deaths are followed by cremation and this figure is likely to rise in the future. This increasing use of cremation as the method of corpse disposal, coupled with the fact that each amalgam restoration is approximately 50% mercury, implies that a significant amount of mercury may be emitted into the environment every year. This study examines mercury released from crematoria in New Zealand. 20 refs., 2 figs., 5 tabs.

  7. Hg, Bi, Cu and Zn distribution in human teeth treated by dental amalgam measured by synchrotron microprobe

    Science.gov (United States)

    Carvalho, M. L.; Marques, J. P.; Brito, J.; Casaca, C.; Cunha, A. S.

    2002-11-01

    Human teeth restored with dental amalgam were analysed by a synchrotron microprobe to evaluate the diffusion of its major constituents, Cu, Zn and Hg, throughout the tooth structures. We measured the elemental distribution inside the tooth from the root to the enamel, specially the region around the amalgam, after its total removal. Hg is present only in restored teeth and concentration profiles show strongly increased levels of this element close to the amalgam region, reaching 500 μg g -1 in one or two cases, decreasing strongly to the inner part of the tooth. Pb concentration profiles do not seem to be affected by metallic amalgam. Very high concentrations of Bi were found in one of the restored teeth, reaching more than 2000 μg g -1, decreasing sharply to the outer regions. The distribution of Mn, Fe, Cu and Zn was also determined in order to evaluate elemental influences by amalgam components. No significant changes in elemental concentrations were detected for Mn and Fe between healthy and restored teeth. However, the levels of Zn and Cu are increased in restored teeth. An X-ray fluorescence set-up with microprobe capabilities, 100 μm of spatial resolution and an energy of 18 keV, installed at LURE synchrotron (France) was used.

  8. Hg, Bi, Cu and Zn distribution in human teeth treated by dental amalgam measured by synchrotron microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, M.L. E-mail: luisa@cii.fc.ul.pt; Marques, J.P.; Brito, J.; Casaca, C.; Cunha, A.S

    2002-11-01

    Human teeth restored with dental amalgam were analysed by a synchrotron microprobe to evaluate the diffusion of its major constituents, Cu, Zn and Hg, throughout the tooth structures. We measured the elemental distribution inside the tooth from the root to the enamel, specially the region around the amalgam, after its total removal. Hg is present only in restored teeth and concentration profiles show strongly increased levels of this element close to the amalgam region, reaching 500 {mu}g g{sup -1} in one or two cases, decreasing strongly to the inner part of the tooth. Pb concentration profiles do not seem to be affected by metallic amalgam. Very high concentrations of Bi were found in one of the restored teeth, reaching more than 2000 {mu}g g{sup -1}, decreasing sharply to the outer regions. The distribution of Mn, Fe, Cu and Zn was also determined in order to evaluate elemental influences by amalgam components. No significant changes in elemental concentrations were detected for Mn and Fe between healthy and restored teeth. However, the levels of Zn and Cu are increased in restored teeth. An X-ray fluorescence set-up with microprobe capabilities, 100 {mu}m of spatial resolution and an energy of 18 keV, installed at LURE synchrotron (France) was used.

  9. High-speed collision of copper nanoparticle with aluminum surface: Molecular dynamics simulation

    Science.gov (United States)

    Pogorelko, Victor V.; Mayer, Alexander E.; Krasnikov, Vasiliy S.

    2016-12-01

    We investigate the effect of the high-speed collision of copper nanoparticles with aluminum surface by means of molecular dynamic simulations. Studied diameter of nanoparticles is varied within the range 7.2-22 nm and the velocity of impact is equal to 500 or 1000 m/s. Dislocation analysis shows that a large quantity of dislocations is formed within the impact area. Overall length of dislocations is determined, first of all, by the impact velocity and by the size of incident copper nanoparticle, in other words, by the kinetic energy of the nanoparticle. Dislocations occupy the total volume of the impacted aluminum single crystal layer (40.5 nm in thickness) in the form of intertwined structure in the case of large kinetic energy of the incident nanoparticle. Decrease in the initial kinetic energy or increase in the layer thickness lead to restriction of the penetration depth of the dislocation net; formation of separate dislocation loops is observed in this case. Increase in the initial system temperature slightly raises the dislocation density inside the bombarded layer and considerably decreases the dislocation density inside the nanoparticle. The temperature increase also leads to a deeper penetration of the copper atoms inside the aluminum. Additional molecular dynamic simulations show that the deposited particles demonstrate a very good adhesion even in the case of the considered relatively large nanoparticles. Medium energy of the nanoparticles corresponding to velocity of about 500 m/s and elevated temperature of the system about 700-900 K are optimal parameters for production of high-quality layers of copper on the aluminum surface. These conditions provide both a good adhesion and a less degree of the plastic deformation. At the same time, higher impact velocities can be used for combined treatment consisting of both the plastic deformation and the coating.

  10. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations

    OpenAIRE

    Fernanda Sardenberg; Clarissa Calil Bonifácio; Mariana Minatel Braga; José Carlos Pettorossi Imparato; Fausto Medeiros Mendes

    2008-01-01

    The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11) were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group -...

  11. Improving the strength of amalgams by including steel fibers

    Energy Technology Data Exchange (ETDEWEB)

    Cochran, Calvin T. [Hendrix College, Conway, AR 72032 (United States); Van Hoose, James R. [Siemens, Orlando, FL 32826 (United States); McGill, Preston B. [Marshall Space Flight Center, EM20, Huntsville, AL 35812 (United States); Grugel, Richard N., E-mail: richard.n.grugel@nasa.gov [Marshall Space Flight Center, EM30, Huntsville, AL 35812 (United States)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer A room temperature liquid Ga-In alloy was successfully substituted for mercury. Black-Right-Pointing-Pointer Physically sound amalgams with included steel fibers can be made. Black-Right-Pointing-Pointer A small volume fraction inclusion of fibers increased strength by {approx}20%. - Abstract: Mercury amalgams, due to their material properties, are widely and successfully used in dental practice. They are, however, also well recognized as having poor tensile strength. With the possibility of expanding amalgam applications it is demonstrated that tensile strength can be increased some 20% by including a small amount of steel fibers. Furthermore, it is shown that mercury can be replaced with a room temperature liquid gallium-indium alloy. Processing, microstructures, and mechanical test results of these novel amalgams are presented and discussed in view of means to further improve their properties.

  12. [Experience with amalgams manufactured by Southern Dental Industries (Australia)].

    Science.gov (United States)

    Tarján, I; Gábris, K; Balaton, P; Dénes, J

    1990-09-01

    The gamma 2 phaseless amalgam of the firm Southern Dental Industries (SDI) was tested. None of the 205 fillings showed level deviations, unevenness, secondary caries and breakage. A minimum size gap was found in 2 cases.

  13. Aligned copper nanorod arrays for highly efficient generation of intense ultra-broadband THz pulses

    CERN Document Server

    Mondal, S; Ding, W J; Hafez, H A; Fareed, M A; Laramée, A; Ropagnol, X; Zhang, G; Sun, S; Sheng, Z M; Zhang, J; Ozaki, T

    2016-01-01

    We demonstrate an intense broadband terahertz (THz) source based on the interaction of relativistic-intensity femtosecond lasers with aligned copper nanorod array targets. For copper nanorod targets with length 5 \\mu m, a maximum 13.8 times enhancement in the THz pulse energy (in $\\leq$ 20 THz spectral range) is measured as compared to that with a thick plane copper target under the same laser conditions. A further increase in the nanorod length leads to a decrease in the THz pulse energy at medium frequencies ($\\leq$ 20THz) and increase of the electromagnetic pulse energy in the high-frequency range (from 20 - 200 THz). For the latter, we measure a maximum energy enhancement of 28 times for the nanorod targets of length 60 \\mu m . Particle-in-cell simulations reveal that THz pulses are mostly generated by coherent transition radiation of laser produced hot electrons, which are efficiently enhanced with the use of nanorod targets. Good agreement is found between the simulation and experimental results.

  14. The Copper Substrate Developments for the HIE-ISOLDE High-Beta Quarter Wave Resonator

    CERN Document Server

    Alberty, L; Aviles, I; Calatroni, S; Capatina, O; Foffano, G; Kadi, Y; Moyret, P; Schirm, K-M; Tardy, T; Venturini Delsolaro, W; D'Elia, A

    2013-01-01

    A new Linac using superconducting Quarter-Wave Resonators (QWRs) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made by niobium sputtered on a bulk copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W. The properties of the cavity substrate have a direct impact on the final cavity performance. The copper substrate has to ensure an optimum surface for the niobium sputtered layer. It has also to fulfil the required geometrical tolerances, the mechanical stability during operation and the thermal performance to optimally extract the RF dissipated power on cavity walls. The paper presents the mechanical design of the high β cavities. The procurement process of the copper raw material is detailed, including specifications and tests. The manufacturing sequence of the complete cavity is then explained and the structural and thermo-mechanical behaviour...

  15. Diffusion bonding and brazing of high purity copper for linear collider accelerator structures

    Directory of Open Access Journals (Sweden)

    J. W. Elmer

    2001-05-01

    Full Text Available Diffusion bonding and brazing of high purity copper were investigated to develop procedures for joining precision machined copper components for the Next Linear Collider (NLC. Diffusion bonds were made over a range of temperatures from 400 °C to 1000 °C, under two different loading conditions [3.45 kPa (0.5 psi and 3.45 MPa (500 psi], and on two different diamond machined surface finishes. Brazes were made using pure silver, pure gold, and gold-nickel alloys, and different heating rates produced by both radiation and induction heating. Braze materials were applied by both physical vapor deposition (PVD and conventional braze alloy shims. Results of the diffusion bonding experiments showed that bond strengths very near that of the copper base metal could be made at bonding temperatures of 700 °C or higher at 3.45 MPa bonding pressure. At lower temperatures, only partial strength diffusion bonds could be made. At low bonding pressures (3.45 kPa, full strength bonds were made at temperatures of 800 °C and higher, while no bonding (zero strength was observed at temperatures of 700 °C and lower. Observations of the fracture surfaces of the diffusion bonded samples showed the effects of surface finish on the bonding mechanism. These observations clearly indicate that bonding began by point asperity contact, and flatter surfaces resulted in a higher percentage of bonded area under similar bonding conditions. Results of the brazing experiments indicated that pure silver worked very well for brazing under both conventional and high heating rate scenarios. Similarly, pure silver brazed well for both the PVD layers and the braze alloy shims. The gold and gold-containing brazes had problems, mainly due to the high diffusivity of gold in copper. These problems led to the necessity of overdriving the temperature to ensure melting, the presence of porosity in the joint, and very wide braze joints. Based on the overall findings of this study, a two

  16. Aggravated neuromuscular symptoms of mercury exposure from dental amalgam fillings.

    Science.gov (United States)

    Akbal, Ayla; Yılmaz, Hınç; Tutkun, Engin; Köş, Durdu Mehmet

    2014-01-01

    Dental amalgam fillings are widely used all over the world. However, their mercury content can lead to various side effects and clinical problems. Acute or chronic mercury exposure can cause several side effects on the central nerve system, renal and hepatic functions, immune system, fetal development and it can play a role on exacerbation of neuromuscular diseases. In this case, we will present a patient with vacuolar myopathy whose symptoms were started and aggravated with her dental amalgam fillings.

  17. Mercury from dental amalgam: exposure and risk assessment.

    Science.gov (United States)

    Koral, Stephen M

    2013-02-01

    There has long been an undercurrent within the dental profession of anti-amalgam sentiment, a "mercury-free" movement. To assess whether anything is or is not scientifically wrong with amalgam, one must look to the vast literature on exposure, toxicology, and risk assessment of mercury. The subject of risk assessment goes straight to the heart of the debate over whether a malgam is safe, or not, for unrestricted use in dentistry in the population at large.

  18. Enhancing lives together: reviewing the process of an organizational amalgamation.

    Science.gov (United States)

    Christoffersen, Emily; Cripps, Donna; Badzioch, Lillian; Sersen, Mary Anne; Flaherty, Brenda; Martin, Murray T

    2010-01-01

    The amalgamation between two hospitals creates a transition period of significant change, uncertainty and complexity. It is a challenging time within an organization that needs to be managed effectively. This article outlines the integration process and eight-step framework used during an amalgamation of an acute hospital organization and a post-acute hospital. The initial process evaluation and lessons learned are also presented.

  19. Regulation of the high-affinity copper transporter (hCtr1) expression by cisplatin and heavy metals.

    Science.gov (United States)

    Liang, Zheng Dong; Long, Yan; Chen, Helen H W; Savaraj, Niramol; Kuo, Macus Tien

    2014-01-01

    Platinum-based antitumor agents have been the mainstay in cancer chemotherapy for many human malignancies. Drug resistance is an important obstacle to achieving the maximal therapeutic efficacy of these drugs. Understanding how platinum drugs enter cells is of great importance in improving therapeutic efficacy. It has been demonstrated that human high-affinity copper transporter 1 (hCtr1) is involved in transporting cisplatin into cells to elicit cytotoxic effects, although other mechanisms may exist. In this communication, we demonstrate that cisplatin transcriptionally induces the expression of hCtr1 in time- and concentration-dependent manners. Cisplatin functions as a competitor for hCtr1-mediated copper transport, resulting in reduced cellular copper levels and leading to upregulated expression of Sp1, which is a positive regulator for hCtr1 expression. Thus, regulation of hCtr1 expression by cisplatin is an integral part of the copper homeostasis regulation system. We also demonstrate that Ag(I) and Zn(II), which are known to suppress hCtr1-mediated copper transport, can also induce hCtr1/Sp1 expression. In contrast, Cd(II), another inhibitor of copper transport, downregulates hCtr1 expression by suppressing Sp1 expression. Collectively, our results demonstrate diverse mechanisms of regulating copper metabolism by these heavy metals.

  20. Studies of cholecystokinin-stimulated biliary secretions reveal a high molecular weight copper-binding substance in normal subjects that is absent in patients with Wilson's disease.

    Science.gov (United States)

    Iyengar, V; Brewer, G J; Dick, R D; Chung, O Y

    1988-03-01

    Copper is unique among cations in that its balance is regulated by the liver. The liver regulates copper balance by excretion of copper (we call it regulatory copper) in the bile destined for loss in the stool. However, most copper secreted into the gastrointestinal tract, for example, that in saliva and gastric juice, is reabsorbed. The biochemical mechanism by which the normal liver "packages" regulatory copper to prevent its reabsorption is not understood. Whatever the mechanism, it appears to have failed in Wilson's disease, because patients with Wilson's disease do not excrete adequate amounts of regulatory copper in their bile to prevent copper accumulation. In the present work, we have studied cholecystokinin-stimulated biliary secretions obtained by intestinal intubation of five normal subjects and five patients with Wilson's disease. Studies of these secretions reveal: (1) that normal but not Wilson's disease biliary samples had a copper-containing peak in the void volume from Sephadex G-75 columns; (2) that the amount of copper in this peak extrapolated to 24 hours of secretion was appropriate to maintain normal copper balance; (3) that the amount of copper in this peak increased with dietary copper supplementation of normal subjects; (4) that normal but not Wilson's disease biliary samples cross-reacted with each of two ceruloplasmin antibodies; and (5) that the high molecular weight Sephadex G-75 fraction from normal but not from Wilson's disease biliary samples cross-reacted with ceruloplasmin antibody. We postulate that the high molecular weight copper-containing substance observed with Sephadex chromatography in normal biliary samples but absent in Wilson's disease samples is the copper-packaging mechanism for copper balance regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Comparison of microstructures in electroformed and spin-formed copper liners of shaped charge undergone high-strain-rate deformation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The as-formed and post-deformed microstructures in both electroformed and spin-formed copper liners of shaped charge were studied by optical microscopy(OM), electron backscattering Kikuchi patterns(EBSP) technique and transmission electron microscopy(TEM). The deformation was carried out at an ultra-high strain rate. OM analysis shows that the initial grains of the electroformed copper liner are finer than those of the spin-formed copper liners. Meanwhile, EBSP analysis reveals that the fiber texture exists in the electroformed copper liners, whereas there is no texture observed in the spin-formed copper liners before deformation. Having undergone high-strain-rate deformation the grains in the recovered slugs, which are transformed from both the electroformed and spin-formed copper liners, all become small. TEM observations of the above two kinds of post-deformed specimens show the existence of cellular structures characterized by tangled dislocations and subgrain boundaries consisting of dislocation arrays. These experimental results indicate that dynamic recovery and recrystallization play an important role in the high-strain-rate deformation process.

  2. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    OpenAIRE

    Simen E. Kopperud; Frode Staxrud; Ivar Espelid; Anne Bjørg Tveit

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the de...

  3. Nanoscale coatings for erosion and corrosion protection of copper microchannel coolers for high powered laser diodes

    Science.gov (United States)

    Flannery, Matthew; Fan, Angie; Desai, Tapan G.

    2014-03-01

    High powered laser diodes are used in a wide variety of applications ranging from telecommunications to industrial applications. Copper microchannel coolers (MCCs) utilizing high velocity, de-ionized water coolant are used to maintain diode temperatures in the recommended range to produce stable optical power output and control output wavelength. However, aggressive erosion and corrosion attack from the coolant limits the lifetime of the cooler to only 6 months of operation. Currently, gold plating is the industry standard for corrosion and erosion protection in MCCs. However, this technique cannot perform a pin-hole free coating and furthermore cannot uniformly cover the complex geometries of current MCCs involving small diameter primary and secondary channels. Advanced Cooling Technologies, Inc., presents a corrosion and erosion resistant coating (ANCERTM) applied by a vapor phase deposition process for enhanced protection of MCCs. To optimize the coating formation and thickness, coated copper samples were tested in 0.125% NaCl solution and high purity de-ionized (DIW) flow loop. The effects of DIW flow rates and qualities on erosion and corrosion of the ANCERTM coated samples were evaluated in long-term erosion and corrosion testing. The robustness of the coating was also evaluated in thermal cycles between 30°C - 75°C. After 1000 hours flow testing and 30 thermal cycles, the ANCERTM coated copper MCCs showed a corrosion rate 100 times lower than the gold plated ones and furthermore were barely affected by flow rates or temperatures thus demonstrating superior corrosion and erosion protection and long term reliability.

  4. High temperature oxidation event of gelatin nanoskin-coated copper fine particles observed by in situ TEM

    Directory of Open Access Journals (Sweden)

    Takashi Narushima

    2012-12-01

    Full Text Available Metallic copper fine particles were prepared using CuO slurry by hydrazine reduction in the presence of gelatin. To observe a behavior of these particles at high temperature, in situ heating TEM observations were carried out. Oxygen gas was introduced and the pressure of the TEM column was kept at 10−3 Pa, corresponding the pressure around the sample at 10−1 Pa. The gelatin, which acts as a protective nanoskin on the particle surface was gradually decomposed. Around approximately 140 °C, it was observed that Cu2O dots formed on the surface of the copper particle. This result is well consistent with the behavior of the TG-DTA curve of the copper fine particles under ambient conditions, and provides key information of oxidative behavior of copper fine particles.

  5. Generating, Detecting, and Analyzing High Frequency Acoustic Signals in Accelerator-Grade Copper

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, Elizabeth L

    2002-12-11

    One of the major limitations on the Next Linear Collider (NLC), a high-gradient particle accelerator in development, is that sparks form within the copper structure, damaging the material. The sparks also generate high frequency acoustic signals that can be used as diagnostics to solve the problem. First, however, the signals' location, attenuation, and propagation must be established, so an effective method for generating and detecting these signals in a simple copper block is necessary. Impact trials with ball bearings and a BB gun as well as tests with a grinder, a laser, and a sparker were conducted to determine how to produce the greatest ratio of high to low frequency acoustic signals. The laser had the largest ratio, but the sparker was chosen because it also had high ratios and was both more practical and more analogous to the actual signals in the accelerator. Further tests were then conducted to determine the best sensor; an International Transducer Corporation 9020 1 N57 was chosen. Subsequent analysis of signals using this setup could establish the location and types of signals and, ultimately, how to solve the problem in the structure.

  6. From quantum matter to high-temperature superconductivity in copper oxides.

    Science.gov (United States)

    Keimer, B; Kivelson, S A; Norman, M R; Uchida, S; Zaanen, J

    2015-02-12

    The discovery of high-temperature superconductivity in the copper oxides in 1986 triggered a huge amount of innovative scientific inquiry. In the almost three decades since, much has been learned about the novel forms of quantum matter that are exhibited in these strongly correlated electron systems. A qualitative understanding of the nature of the superconducting state itself has been achieved. However, unresolved issues include the astonishing complexity of the phase diagram, the unprecedented prominence of various forms of collective fluctuations, and the simplicity and insensitivity to material details of the 'normal' state at elevated temperatures.

  7. High Stability Performance of Superhydrophobic Modified Fluorinated Graphene Films on Copper Alloy Substrates

    Directory of Open Access Journals (Sweden)

    Rafik Abbas

    2017-01-01

    Full Text Available A stable self-cleaning superhydrophobic modified fluorinated graphene surface with micro/nanostructure was successfully fabricated on copper substrates via drop coating process. Irregularly stacked island-like multilayered fluorinated graphene nanoflakes comprised the microstructure. The fabricated films exhibited outstanding superhydrophobic property with a water contact angle 167° and water sliding angle lower than 4°. The developed superhydrophobic surface showed excellent corrosion resistance with insignificant decrease of water contact angle 166° in 3.5 wt.% NaCl solution. This stable highly hydrophobic performance of the fluorinated graphene films could be useful in self-cleaning, antifogging, corrosion resistive coatings and microfluidic devices.

  8. Effects of High Salt Concentration and Residue on Copper and Aluminum Corrosion

    Institute of Scientific and Technical Information of China (English)

    HUO Ying; TAN Mike; Yong jun; SHU Li

    2013-01-01

    Traditional researches on metal corrosion under salt solutions deposit conditions are usually carried out by visual,electron microscopic observations and simple electrochemical measurement via a traditional one-piece electrode.These techniques have difficulties in measuring localized corrosion that frequently occur in inhomogeneous media.This paper reports the results from the experiments using specially shaped coupons and a relatively new method of measuring heterogeneous electrochemical processes,namely,the wire beam electrode(WBE).Preliminary results from copper and aluminum corrosion in highly concentrated sodium chloride solutions with and without solid deposits show that the method is useful in simulating and studying corrosion especially localized corrosion in pipelines.

  9. Synthesis of highly stable, water-dispersible copper nanoparticles as catalysts for nitrobenzene reduction.

    Science.gov (United States)

    Kaur, Ravneet; Giordano, Cristina; Gradzielski, Michael; Mehta, Surinder K

    2014-01-01

    We report an aqueous-phase synthetic route to copper nanoparticles (CuNPs) using a copper-surfactant complex and tests of their catalytic efficiency for a simple nitrophenol reduction reaction under atmospheric conditions. Highly stable, water-dispersed CuNPs were obtained with the aid of polyacrylic acid (PAA), but not with other dispersants like surfactants or polymethacrylic acid (PMAA). The diameter of the CuNPs could be controlled in the range of approximately 30-85 nm by modifying the ratio of the metal precursor to PAA. The catalytic reduction of p-nitrophenol to p-aminophenol takes place at the surface of CuNPs at room temperature and was accurately monitored by UV/Vis spectroscopy. The catalytic efficiency was found to be remarkably high for these PAA-capped CuNPs, given the fact that at the same time PAA is efficiently preventing their oxidation as well. The activity was found to increase as the size of the CuNPs decreased. It can therefore be concluded that the synthesized CuNPs are catalytically highly efficient in spite of the presence of a protective PAA coating, which provides them with a long shelf life and thereby enhances the application potential of these CuNPs. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. High-temperature experimental and thermodynamic modelling research on the pyrometallurgical processing of copper

    Science.gov (United States)

    Hidayat, Taufiq; Shishin, Denis; Decterov, Sergei A.; Hayes, Peter C.; Jak, Evgueni

    2017-01-01

    Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.

  11. A simple granulation technique for preparing high-porosity nano copper oxide(Ⅱ) catalyst beads

    Institute of Scientific and Technical Information of China (English)

    Seyed Javad Ahmadia; Mohammad Outokesh; Morteza Hosseinpour; Tahereh Mousavand

    2011-01-01

    A simple and efficient method was developed for fabricating spherical granules of CuO catalyst via a three-step procedure.In the first step,copper oxide nanoparticles were synthesized by hydrothermal decomposition of copper nitrate solution under supercritical condition.Then,they were immobilized in the polymeric matrix of calcium alginate,and followed by high-temperature calcination in an air stream as the third step,in which carbonaceous materials were oxidized,to result in a pebble-type catalyst of high porosity.The produced CuO nanoparticles were characterized by transmission electron microscopy (TEM) that revealed an average size of 5 nm,X-ray diffractometry (XRD),and thermo gravimetric (TG)analysis.The catalysts were further investigated by BET test for measurement of their surface area,and by temperature-programmed reduction analysis (H2-TPR) for determination of catalytic activity.The results demonstrated that immobilization of the CuO nanoparticle in the polymeric matrix of calcium alginate,followed by calcination at elevated temperatures,could result in notable mechanical strength and enhanced catalytic activity due to preservation of the high surface area,both valuable for practical applications.

  12. Liquid phase conversion of Glycerol to Propanediol over highly active Copper/Magnesia catalysts

    Indian Academy of Sciences (India)

    Satyanarayana Murty Pudi; Abdul Zoeb; Prakash Biswas; Shashi Kumar

    2015-05-01

    In this work, a series of Cu/MgO catalysts with different copper metal loading were prepared by the precipitation-deposition method. Their catalytic behaviour was investigated for glycerol hydrogenolysis to 1,2-propanediol (1,2-PDO). The physico-chemical properties of the catalysts were characterized by various techniques such as BET surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR), NH3-temperature programmed desorption (NH3-TPD) and scanning electron microscopy (SEM) methods. The characterization results showed that the copper metal was well-dispersed over MgO support and a new phase Cu-MgO was also identified from XRD results after calcination. The 25Cu/MgO (Cu:25 wt%) catalyst exhibited the highest glycerol conversion of 88.7% and 1,2-PDO selectivity of 91.7% at 210°C, 4.5MPa of hydrogen pressure after 12 h. The high glycerol conversion was mainly due to the Cu dispersion on MgO support and high acidic strength. Further, the effects of temperature, hydrogen pressure, catalyst loading and glycerol concentration were studied over 25Cu/MgO catalyst for optimization of reaction parameters. Kinetic study over highly active 25Cu/MgO catalyst showed that the reaction followed the pseudo second order rate with respect to glycerol and the apparent activation energy was found to be 28.7 ± 0.8 kcal/mol.

  13. Growth of copper oxide nanocrystals in metallic nanotubes for high performance battery anodes.

    Science.gov (United States)

    Zhao, Yuxin; Mu, Shanjun; Sun, Wanfu; Liu, Quanzhen; Li, Yanpeng; Yan, Zifeng; Huo, Ziyang; Liang, Wenjie

    2016-12-08

    A rational integration of 1D metallic nanotubes and oxide nanoparticles has been demonstrated as a viable strategy for the production of both highly stable and efficient anodes for lithium ion batteries. We encapsulated copper oxide (CuO) nanoparticles in ultra-long metallic copper nanotubes with engineered interspaces, and explored their electrochemical properties. Such a hierarchical architecture provides three important features: (i) a continuous nanoscale metallic Cu shell to minimize electronic/ionic transmitting impedance; (ii) a unique quasi-one-dimensional structure with a large aspect ratio to reduce self-aggregation; (iii) free space for volume expansion of CuO nanoparticles and stable solid-electrolyte interphase (SEI) formation. The anode materials with such hierarchical structures have high specific capacity (around 600 mA h g(-1) at a current density of 0.1 A g(-1)), excellent cycling stability (over 94% capacity retention after 200 cycles) and superb reversible capacity of 175 mA h g(-1) at a high charging rate of 15 A g(-1).

  14. Highly efficient visual detection of trace copper(II) and protein by the quantum photoelectric effect.

    Science.gov (United States)

    Wang, Peng; Lei, Jianping; Su, Mengqi; Liu, Yueting; Hao, Qing; Ju, Huangxian

    2013-09-17

    This work presented a photocurrent response mechanism of quantum dots (QDs) under illumination with the concept of a quantum photoelectric effect. Upon irradiation, the photoelectron could directly escape from QDs. By using nitro blue tetrazolium (NBT) to capture the photoelectron, a new visual system was proposed due to the formation of an insoluble reduction product, purple formazan, which could be used to visualize the quantum photoelectric effect. The interaction of copper(II) with QDs could form trapping sites to interfere with the quantum confinement and thus blocked the escape of photoelectron, leading to a "signal off" visual method for sensitive copper(II) detection. Meanwhile, by using QDs as a signal tag to label antibody, a "signal on" visual method was also proposed for immunoassay of corresponding protein. With meso-2,3-dimercaptosuccinic-capped CdTe QDs and carcino-embryonic antigen as models, the proposed visual detection methods showed high sensitivity, low detection limit, and wide detectable concentration ranges. The visualization of quantum photoelectric effect could be simply extended for the detection of other targets. This work opens a new visual detection way and provides a highly efficient tool for bioanalysis.

  15. Microleakage of bonded amalgam restorations using different adhesive agents with dye under vacuum: An in vitro study

    Directory of Open Access Journals (Sweden)

    Abhishek Parolia

    2011-01-01

    Clinical Significance: Bonded amalgam restorations prevent over-preparation and reduce the tooth flexure. GIC type I under amalgam provides chemical bonding in between amalgam and tooth structure and thus reduces the microleakage.

  16. Monte Carlo dose calculation in dental amalgam phantom.

    Science.gov (United States)

    Aziz, Mohd Zahri Abdul; Yusoff, A L; Osman, N D; Abdullah, R; Rabaie, N A; Salikin, M S

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  17. Dentin Pre-Treatment to Suppress Microleakage of Amalgam Restorations

    Directory of Open Access Journals (Sweden)

    Yosi Kusuma Eriwati Arianto

    2015-10-01

    Full Text Available Diminished microleakage of amalgam-to-dentin preparations would benefit large populations in public health facilities. Prior studies demonstrated less microleakage for bonded amalgams than similarly bonded advanced composites among 30 different composite/bonding agent/storage conditions, Haller et al. showed that a combination of formaldehyde pre-treatment and glutaraldehyde-containing Syntac adhesive minimized microleakage. In the current study, CLass V restorations (groups of 10 formaldehyde-treated non carious human molars were filled with Valiant (Ivoclar NA amalgam after application of one of three liners: Copalite varnish; Amalagambond Plus with microfiber; and Syntac/Variolink. The control group used no liner material. After 24 hours at 37°C/100% RH, samples were thermocycled (1000 eyeles in water at 5°C and 60°C (15 second dwell time in each. Samples were immersed in 5% methylene blue solution (4 hrs and observed under a stereomicroscope; interfaces also were examined by SEM. Krsukal Wallis ANOVA by ranks (P<0.01 and Mann Whitney U Tests (P<0.05 of the data indicate improvements (equivalent among the 3 different liners tested here over unlined amalgam preparations. Liner/aldehyde-crosslinked dentin interphases, without technique-sensitive composites, may minimize microleakage by improving amalgam contact (physical bonding.

  18. Evaluation of genotoxic effect of amalgam restorations in oral cavity

    Directory of Open Access Journals (Sweden)

    Chennoju Sai Kiran

    2015-01-01

    Full Text Available Background: Mercury a popular heavy metal used in dentistry in the form of amalgam is a known clastogen. The assessment of micronuclei in cells is a promising tool for studying the genotoxic effect of mercury on them. Hence, a study was conducted to evaluate the frequency of micronuclei in exfoliated buccal cells of subjects with amalgam restorations. Materials and Methods: A total of 60 subjects (age and gender-matched sample of 30 study group and 30 control group were included in this study. Smears were obtained with moistened wooden spatula from buccal mucosa in close contact with amalgam restoration and fixed with 100% ethyl alcohol. After staining with Papanicolaou stain, all the slides were examined under ×40 and 1,000 cells were counted for the presence of micronuclei. The data were entered into a spread sheet and subjected to statistical analysis. Results: A statistically significant increase in the number of micronuclei containing cells was observed in the study group when compared to control group (P < 0.05. A positive correlation was observed between the duration of restoration and frequency of micronuclei (P < 0.05. Conclusion: The results showed a definite genotoxic effect of amalgam restorations on the oral cavity which can be attributed to the clastogenic action of mercury in amalgam restorations.

  19. Monte carlo dose calculation in dental amalgam phantom

    Directory of Open Access Journals (Sweden)

    Mohd Zahri Abdul Aziz

    2015-01-01

    Full Text Available It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC. On the other hand, computed tomography (CT images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  20. Influence of a High-Pressure Comminution Technology on Concentrate Yields in Copper Ore Flotation Processes

    Directory of Open Access Journals (Sweden)

    Saramak D.

    2014-10-01

    Full Text Available The article concerns the issues of flotation process effectiveness in relationship to the operating conditions of a high-pressure comminution process course. Experimental programme covering a flotation laboratory batch tests was a verification technique of a high-pressure crushing operations course. The most favorable values of flotation concentrate weight recoveries were obtained for the pressing force 6 kN and 4% of the feed moisture. It was also determined the model of the concentrate weight recovery as a function of pressing force in the press and feed moisture content. This model was the basis for the optimization of effects of copper ore flotation processes preceded in high-pressure crushing operation in roller presses.

  1. Deformation and failure of OFHC copper under high strain rate shear compression

    Science.gov (United States)

    Ruggiero, Andrew; Testa, Gabriel; Bonora, Nicola; Iannitti, Gianluca; Persechino, Italo; Colliander, Magnus Hörnqvist

    2017-01-01

    Hat-shaped specimen geometries were developed to generate high strain, high-strain-rates deformation under prescribed conditions. These geometries offer also the possibility to investigate the occurrence of ductile rupture under low or negative stress triaxiality, where most failure models fail. In this work, three tophat geometries were designed, by means of extensive numerical simulation, to obtain desired stress triaxiality values within the shear region that develops across the ligament. Material failure was simulated using the Continuum Damage Model (CDM) formulation with a unilateral condition for damage accumulation and validated by comparing with quasi-static and high strain rate compression tests results on OFHC copper. Preliminary results seem to indicate that ductile tearing initiates at the specimen corner location where positive stress triaxiality occurs because of local rotation and eventually propagates along the ligament.

  2. Inhibition of human high-affinity copper importer Ctr1 orthologous in the nervous system of Drosophila ameliorates Aβ42-induced Alzheimer's disease-like symptoms.

    Science.gov (United States)

    Lang, Minglin; Fan, Qiangwang; Wang, Lei; Zheng, Yajun; Xiao, Guiran; Wang, Xiaoxi; Wang, Wei; Zhong, Yi; Zhou, Bing

    2013-11-01

    Disruption of copper homeostasis has been implicated in Alzheimer's disease (AD) during the last 2 decades; however, whether copper is a friend or a foe is controversial. Within a genetically tractable Drosophila AD model, we manipulated the expression of human high-affinity copper importer orthologous in Drosophila to explore the in vivo roles of copper ions in the development of AD. We found that inhibition of Ctr1C expression by RNAi in Aβ-expressing flies significantly reduced copper accumulation in the brains of the flies as well as ameliorating neurodegeneration, enhancing climbing ability, and prolonging lifespan. Interestingly, Ctr1C inhibition led to a significant increase in higher-molecular-weight Aβ42 forms in brain lysates, whereas it was accompanied by a trend of decreased expression of amyloid-β degradation proteases (including NEP1-3 and IDE) with age and reduced Cu-Aβ interaction-induced oxidative stress in Ctr1C RNAi flies. Similar results were obtained from inhibiting another copper importer Ctr1B and overexpressing a copper exporter DmATP7 in the nervous system of AD flies. These results imply that copper may play a causative role in developing AD, as either Aβ oligomers or aggregates were less toxic in a reduced copper environment or one with less copper binding. Early manipulation of brain copper uptake can have a great effect on Aβ pathology.

  3. MOBILITY OF MERCURY OF THE DENTAL AMALGAM IN REDUCTION PROCESS

    Directory of Open Access Journals (Sweden)

    Raquel Dalla Costa

    2008-10-01

    Full Text Available The dental wastewater can contribute to the total daily mercury load on environment. Factorial design of experiments is useful to analysis of factors that influence in this mobility. The aim of the present study was to design experiments to examine the effects of operational variables – temperature, pH and contact time - which may affect the mobility of mercury in form of dental amalgam residue in reduction process in the sediments of the Pirapó River. Based on the factorial design of experiments and the analysis of variance, the temperature was the most significant factor in this process, followed by the pH and contact time. The parameters affecting the mobility of total mercury showed that when the temperature and contact time increases and pH decreases there is an important increase of mercury concentration in process. For the tested conditions, the high total mercury concentration was obtained using the temperature = 35oC, pH = 4.0 and contact time = 10 days.

  4. Easy Access to Metallic Copper Nanoparticles with High Activity and Stability for CO Oxidation.

    Science.gov (United States)

    Gonçalves, Renato V; Wojcieszak, Robert; Wender, Heberton; Sato B Dias, Carlos; Vono, Lucas L R; Eberhardt, Dario; Teixeira, Sergio R; Rossi, Liane M

    2015-04-22

    Copper catalysts are very promising, affordable alternatives for noble metals in CO oxidation; however, the nature of the active species remains unclear and differs throughout previous reports. Here, we report the preparation of 8 nm copper nanoparticles (Cu NPs), with high metallic content, directly deposited onto the surface of silica nanopowders by magnetron sputtering deposition. The as-prepared Cu/SiO2 contains 85% Cu0 and 15% Cu2+ and was enriched in the Cu0 phase by H2 soft pretreatment (96% Cu0 and 4% Cu2+) or further oxidized after treatment with O2 (33% Cu0 and 67% Cu2+). These catalysts were studied in the catalytic oxidation of CO under dry and humid conditions. Higher activity was observed for the sample previously reduced with H2, suggesting that the presence of Cu-metal species enhances CO oxidation performance. Inversely, a poorer performance was observed for the sample previously oxidized with O2. The presence of water vapor caused only a small increase in the temperature require for the reaction to reach 100% conversion. Under dry conditions, the Cu NP catalyst was able to maintain full conversion for up to 45 h at 350 °C, but it deactivated with time on stream in the presence of water vapor.

  5. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    Science.gov (United States)

    Kopperud, Simen E.; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations. PMID:27110804

  6. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    Directory of Open Access Journals (Sweden)

    Simen E. Kopperud

    2016-04-01

    Full Text Available Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%, followed by restoration fractures (25.1%. Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p < 0.01, employees in the Public Dental Service (PDS (p < 0.01 and dentists working in counties with low dentist density (p = 0.03. There was a tendency towards choosing minimally invasive treatment among dentists who also avoided operative treatment of early approximal lesions (p < 0.01. Norwegian dentists showed positive attitudes towards composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations.

  7. Fracture resistance of premolars with bonded class II amalgams.

    Science.gov (United States)

    Dias de Souza, Grace Mendonça; Pereira, Gisele Damiana Silveira; Dias, Carlos Tadeu Santos; Paulillo, Luis Alexandre Maffei Sartini

    2002-01-01

    This study evaluated the fracture resistance of maxillary premolars with MOD cavity preparation and simulated periodontal ligament. The teeth were restored with silver amalgam (G1), Scotchbond Multi-Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test in the Universal Testing Machine (Instron). The statistical analysis of the results (ANOVA and Tukey Test) revealed that the fracture resistance of group 2 (G2=105.720 kgF) was superior to those of groups 1 (G1=72.433 kgF) and 3 (G3=80.505 kgF) that did not differ between them.

  8. Novel Amalgams for In-Space Fabrication of Replacement Parts

    Science.gov (United States)

    Cochran, Calvin T.; Van Hoose, James R.; Grugel, R. N.

    2012-01-01

    Being able to fabricate replacement parts during extended space flight missions precludes the weight, storage volume, and speculation necessary to accommodate spares. Amalgams, widely used in dentistry, are potential candidates for fabricating parts in microgravity environments as they are moldable, do not require energy for melting, and do not pose fluid handling problems. Unfortunately, amalgams have poor tensile strength and the room temperature liquid component is mercury. To possibly resolve these issues a gallium-indium alloy was substituted for mercury and small steel fibers were mixed in with the commercial alloy powder. Subsequent microscopic examination of the novel amalgam revealed complete bonding of the components, and mechanical testing of comparable samples showed those containing steel fibers to have a significant improvement in strength. Experimental procedures, microstructures, and test results are presented and discussed in view of further improving properties.

  9. Amalgamated Products of Ore and Quadratic Extensions of Rings

    CERN Document Server

    Johnson, Garrett

    2012-01-01

    We study the ideal theory of amalgamated products of Ore and quadratic extensions over a base ring R. We prove an analogue of the Hilbert Basis theorem for an amalgamated product Q of quadratic extensions and determine conditions for when the one-sided ideals of Q are principal or doubly-generated. We also determine conditions that make Q a principal ideal ring. Finally, we show that the double affine Hecke algebra $H_{q,t}$ associated to the general linear group GL_2(k) (here, k is a field with characteristic not 2) is an amalgamated product of quadratic extensions over a three-dimensional quantum torus and give an explicit isomorphism. In this case, it follows that $H_{q,t}$ is a noetherian ring.

  10. Longevity of dental amalgam in comparison to composite materials

    Directory of Open Access Journals (Sweden)

    Windisch, Friederike

    2008-11-01

    Full Text Available Health political background: Caries is one of the most prevalent diseases worldwide. For (direct restaurations of carious lesions, tooth-coloured composite materials are increasingly used. The compulsory health insurance pays for composite fillings in front teeth; in posterior teeth, patients have to bear the extra cost. Scientific background: Amalgam is an alloy of mercury and other metals and has been used in dentistry for more than one hundred and fifty years. Composites consist of a resin matrix and chemically bonded fillers. They have been used for about fifty years in front teeth. Amalgam has a long longevity; the further development of composites has also shown improvements regarding their longevity. Research questions: This HTA-report aims to evaluate the longevity (failure rate, median survival time (MST, median age of direct amalgam fillings in comparison to direct composite fillings in permanent teeth from a medical and economical perspective and discusses the ethical, legal and social aspects of using these filling materials. Methods: The systematic literature search yielded a total of 1,149 abstracts. After a two-step selection process based on defined criteria 25 publications remained to be assessed. Results: The medical studies report a longer longevity for amalgam fillings than for composite fillings. However, the results of these studies show a large heterogeneity. No publication on the costs or the cost-effectiveness of amalgam and composite fillings exists for Germany. The economic analyses (NL, SWE, GB report higher costs for composite fillings when longevity is assumed equal (for an observation period of five years or longer for amalgam compared to composite fillings. These higher costs are due to the higher complexity of placing composite fillings. Discussion: Due to different study designs and insufficient documentation of study details, a comparison of different studies on longevity of direct amalgam and composite

  11. Amalgam buildups: shear strength and dentin sealing properties.

    Science.gov (United States)

    Pashley, E L; Comer, R W; Parry, E E; Pashley, D H

    1991-01-01

    The retentive strength and sealing properties of amalgam buildups were compared in vitro in three groups of specimens. All teeth were prepared with flat, nonretentive surfaces. In the first group, the amalgam buildups were retained by four self-threading Minim pins. In the second group, retention was provided by a circumferential slot prepared in the dentin just inside the DEJ. The third group utilized an adhesive resin for retention. Dentin permeability was measured as a hydraulic conductance before and after placement of the amalgam buildups and before and after thermocycling. All methods of retention sealed dentin very well even in the absence of cavity varnish. The 90 degree retentive strength was: pins, 10.3 +/- 0.9 MPa; slots, 4.1 +/- 0.5 MPa; resin, 3.1 +/- 0.8 MPa (mean +/- SEM).

  12. Breakage of Curved Copper Wires Caused by High Impulse Current of Lightning

    Science.gov (United States)

    Hu, Xiaobo; Inaba, Tsuginori; Kindersberger, Josef

    In past studies, after thin straight copper wires of 0.1mmφ were exposed to an impulse current, their temperature rose; they melted according to the specific pre-arcing Joule integral in an adiabatic state. However, in this study, we confirmed that thick straight copper wires of 1mmφ and over it were broken in a solid state before melting The effect of physical damage on copper wire performance was confirmed. The test data suggest that ohmic heating is the main reason for thin (less than 1mmφ) copper wire breakage in the experiments. However, the magnetic force and skin effect are primarily responsible for breaking thick copper wires rather than thermal failure, as previously thought. And the thicker the copper wires diameter was, the more noticeable the magnetic force and skin effect were. Then the impulse current was impressed through curved copper wires from 0.3mmφ to 2.0mmφ. Because of different breakage mechanism for thin and thick copper wires, the current-carrying capability of thin curved copper wires did not change comparing to that of straight ones. However, the current-carrying capability of thick copper wires greatly decreased when they were curved.

  13. Copper Selenide Nanocrystals as a High Performance, Solution Processed Thermoelectric Material

    Science.gov (United States)

    Forster, Jason; Lynch, Jared; Coates, Nelson; Sahu, Ayaskanta; Liu, Jun; Cahill, David; Urban, Jeff

    Nano-structuring a thermoelectric material often results in enhanced performance due to a decrease in the materials' thermal conductivity. Traditional nano-structuring techniques involve ball milling a bulk material followed by spark plasma sintering, a very energy intensive process. In this talk, we will describe the development of a self-assembled, high-performing, nano-structured thin film based on copper selenide nanocrystals. Mild thermal annealing of these films results in concurrent increases in the Seebeck coefficient and electrical conductivity. We are able to achieve power factors at room temperature that are as high as the best spark plasma sintered materials. These solution-processed films have potential applications as conformal, flexible materials for thermoelectric power generation.

  14. Room temperature creep-fatigue response of selected copper alloys for high heat flux applications

    DEFF Research Database (Denmark)

    Li, M.; Singh, B.N.; Stubbins, J.F.

    2004-01-01

    Two copper alloys, dispersion-strengthened CuAl25 and precipitation-hardened CuCrZr, were examined under fatigue and fatigue with hold time loading conditions. Tests were carried out at room temperature and hold times were imposed at maximum tensile and maximum compressive strains. It was found...... times. The influence of hold times on fatigue life in the low cycle fatigue, short life regime (i.e., at high strain amplitudes) was minimal. When hold time effects were observed, fatigue lives were reduced with hold times as short as two seconds. Appreciable stress relaxation was observed during...... the hold period at all applied strain levels in both tension and compression. In all cases, stresses relaxed quickly within the first few seconds of the hold period and much more gradually thereafter. The CuAl25 alloy showed a larger effect of hold time on reduction of high cycle fatigue life than did...

  15. High emittance black nickel coating on copper substrate for space applications

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaram, Soniya, E-mail: jrf0013@isac.gov.in; Pillai, Anju M., E-mail: anjum@isac.gov.in; Rajendra, A., E-mail: rajendra@isac.gov.in; Sharma, A.K., E-mail: aks@isac.gov.in

    2015-09-15

    Highlights: • High emittance black nickel coating is obtained on copper substrate. • The effect of various process parameters on IR emittance is studied systematically. • Process parameters are optimized to develop a high emittance black nickel coating. • Coating obtained using the finalized parameters exhibited an emittance of 0.83. • SEM and EDAX are used for coating characterization. - Abstract: Black nickel, an alloy coating of zinc and nickel, is obtained on copper substrate by pulse electrodeposition from a modified Fishlock bath containing nickel sulphate, nickel ammonium sulphate, zinc sulphate and ammonium thiocyanate. A nickel undercoat of 4–5 μm thickness is obtained using Watts bath to increase the corrosion resistance and adhesion of the black nickel coating. The effect of bath composition, temperature, solution pH, current density and plating time on the coating appearance and corresponding infra-red emittance of the coating is investigated systematically. Process parameters are optimized to develop a high emittance space worthy black nickel coating to improve the heat radiation characteristics. The effect of the chemistry of the plating bath on the coating composition was studied using energy dispersive X-ray analysis (EDAX) of the coatings. The 5–6 μm thick uniform jet black zinc–nickel alloy coating obtained with optimized process exhibited an emittance of 0.83 and an absorbance of 0.92. The zinc to nickel ratio of black nickel coatings showing high emittance and appealing appearance was found to be in the range 2.3–2.4.

  16. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    Directory of Open Access Journals (Sweden)

    Neda Bahremandi Tolou

    2011-01-01

    Conclusion: By adding nano particles of titania and preparing amalgam/titania nano composite as a dental amalgam, corrosion behavior and mercury release during the 2 st h after preparation could be improved.

  17. Radial multipliers on amalgamated free products of II-factors

    DEFF Research Database (Denmark)

    Möller, Sören

    2014-01-01

    Let ℳi be a family of II1-factors, containing a common II1-subfactor 풩, such that [ℳi : 풩] ∈ ℕ0 for all i. Furthermore, let ϕ: ℕ0 → ℂ. We show that if a Hankel matrix related to ϕ is trace-class, then there exists a unique completely bounded map Mϕ on the amalgamated free product of the ℳi...... with amalgamation over 풩, which acts as a radial multiplier. Hereby, we extend a result of Haagerup and the author for radial multipliers on reduced free products of unital C*- and von Neumann algebras....

  18. Jiangxi Copper Co.,Ltd Invested 268 Million Yuan to Expand the Capacity of High-Grade Copper Foil Production to 5000 ton/year

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>At the end of 2008, Jiangxi Copper Co.,Ltd reviewed and approved the"Proposal on In- vesting 268 Million Yuan to Jiangxi Copper- Yates Foil Inc for Technical Upgrade and Phase-two Expansion of Capacity."

  19. A dose-dependent relationship between mercury exposure from dental amalgams and urinary mercury levels: a further assessment of the Casa Pia Children's Dental Amalgam Trial.

    Science.gov (United States)

    Geier, D A; Carmody, T; Kern, J K; King, P G; Geier, Mark R

    2012-01-01

    Dental amalgams are a commonly used dental restorative material, and amalgams are about 50% mercury (Hg). In our study, urinary Hg levels was examined in children of age 8-18 years, with and without dental amalgam fillings, from a completed clinical trial (parent study) that was designed to evaluate the potential health consequences of prolonged exposure to Hg from dental amalgam fillings. Our study was designed to determine whether there was a significant dose-dependent correlation between increasing Hg exposure from dental amalgams and urinary Hg levels. Hg exposure depends on the size and number of teeth with dental amalgams. Overall, consistent with the results observed in the parent study, there was a statistically significant dose-dependent correlation between cumulative exposure to Hg from dental amalgams and urinary Hg levels, after covariate adjustment. Further, it was observed that urinary Hg levels increased by 18% to 52% among 8 to 18 year old individuals, respectively, with an average exposure to amalgams, in comparison to study subjects with no exposure to amalgams. The results of our study suggest that dental amalgams contribute to ongoing Hg exposure in a dose-dependent fashion.

  20. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    OpenAIRE

    Neda Bahremandi Tolou; Mohammadhossein Fathi; Ahmad Monshi; Vajihesadat Mortazavi; Farzaneh Shirani

    2011-01-01

    Background: Many attempts have been performed and continued for improvement of dental amalgam properties during last decades. The aim of present research was fabrication and characterization of amalgam/titania nano composite and evaluation of its corrosion behavior. Materials and Methods: In this experimental research, nano particles of titania were added to initial amalgam alloy powder and then, dental amalgam was prepared. In order to investigate the effect of nano particle amounts on p...

  1. Scalp hair and saliva as biomarkers in determination of mercury levels in Iranian women: Amalgam as a determinant of exposure

    Energy Technology Data Exchange (ETDEWEB)

    Fakour, H., E-mail: fakour.h@gmail.com [Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Mazandaran (Iran, Islamic Republic of); Esmaili-Sari, A. [Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Mazandaran (Iran, Islamic Republic of); Zayeri, F. [Department of Biostatistics, Faculty of Paramedical Sciences and Proteomics Research Center, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2010-05-15

    The aim of this study was to determine the relationship between mercury concentrations in saliva and hair in women with amalgam fillings and its relation with age and number of amalgam fillings. Eighty-two hair and saliva samples were collected randomly from Iranian women who have the same fish consumption pattern and free from occupational exposures. The mean {+-} SD age of these women was 29.37 {+-} 8.12 (ranged from 20 to 56). The determination of Hg level in hair samples was carried out by the LECO, AMA 254, Advanced Mercury Analyzer according to ASTM, standard No. D-6722. Mercury concentration in saliva samples was analyzed by PERKIN-ELMER 3030 Cold Vapor Atomic Absorption Spectrophotometer. The mean {+-} SD mercury level in the women was 1.28 {+-} 1.38 {mu}g/g in hair and 4.14 {+-} 4.08 {mu}g/l in saliva; and there were positive correlation among them. A significant correlation was also observed between Hg level of saliva (Spearman's {rho} = 0.93, P < 0.001) and hair (Spearman's {rho} = 0.92, P < 0.001) with number of amalgam fillings. According to the results, we can conclude that amalgam fillings may be an effective source for high Hg concentration in hair and releasing the mercury to the saliva samples.

  2. The use of amalgam powder and calcium hydroxide to recreate a radiopaque image of a lost dental restoration.

    Science.gov (United States)

    Shiroma, Calvin Y

    2002-05-01

    Radiographs of dental restorations are highly reliable when used to identify postmortem dental remains. A problem exists if key dental restorations are missing or defective, which results in the loss of a comparative radiographic image. This article describes a simple method allowing the odontologist to quickly recreate a temporary radiopaque restoration. This article presents a method of using amalgam powder (radiopaque material) and calcium hydroxide (radiopaque material and transport medium for the amalgam powder) to recreate a radiopaque image on a tooth that has lost a dental restoration. Amalgam powder and calcium hydroxide is easily obtained (in any dental office), fairly clean, easy to manipulate, inexpensive, inert, stable, and able to be removed without damaging the dental remains. The amalgam powder/calcium hydroxide mixture can easily be re-shaped or modified to reflect the radiopaque image of the original restoration. Radiographic comparison of the "restored" dental remains to the antemortem radiographs is now possible. The use of this technique is presented in a case report.

  3. Copper Chaperone for Cu/Zn Superoxide Dismutase is a sensitive biomarker of mild copper deficiency induced by moderately high intakes of zinc

    Directory of Open Access Journals (Sweden)

    L'Abbé Mary R

    2005-11-01

    Full Text Available Abstract Background Small increases in zinc (Zn consumption above recommended amounts have been shown to reduce copper (Cu status in experimental animals and humans. Recently, we have reported that copper chaperone for Cu/Zn superoxide dismutase (CCS protein level is increased in tissues of overtly Cu-deficient rats and proposed CCS as a novel biomarker of Cu status. Methods Weanling male Wistar rats were fed one of four diets normal in Cu and containing normal (30 mg Zn/kg diet or moderately high (60, 120 or 240 mg Zn/kg diet amounts of Zn for 5 weeks. To begin to examine the clinical relevance of CCS, we compared the sensitivity of CCS to mild Cu deficiency, induced by moderately high intakes of Zn, with conventional indices of Cu status. Results Liver and erythrocyte CCS expression was significantly (P P Conclusion Collectively, these data show that CCS is a sensitive measure of Zn-induced mild Cu deficiency and demonstrate a dose-dependent biphasic response for reduced Cu status by moderately high intakes of Zn.

  4. Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

    Science.gov (United States)

    Schöffler, Anne L; Makarem, Ata; Rominger, Frank

    2016-01-01

    Summary A dinuclear N-heterocyclic carbene (NHC) copper complex efficiently catalyzes azide–alkyne cycloaddition (CuAAC) “click” reactions. The ancillary ligand comprises two 4,5-dimethyl-1,3-thiazol-2-ylidene units and an ethylene linker. The three-step preparation of the complex from commercially available starting compounds is more straightforward and cost-efficient than that of the previously described 1,2,4-triazol-5-ylidene derivatives. Kinetic experiments revealed its high catalytic CuAAC activity in organic solvents at room temperature. The activity increases upon addition of acetic acid, particularly for more acidic alkyne substrates. The modular catalyst design renders possible the exchange of N-heterocyclic carbene, linker, sacrificial ligand, and counter ion. PMID:27559407

  5. Clustered ribbed-nanoneedle structured copper surfaces with high-efficiency dropwise condensation heat transfer performance.

    Science.gov (United States)

    Zhu, Jie; Luo, Yuting; Tian, Jian; Li, Juan; Gao, Xuefeng

    2015-05-27

    We report that the dropwise condensation heat transfer (DCHT) effectiveness of copper surfaces can be dramatically enhanced by in situ grown clustered ribbed-nanoneedles. Combined experiments and theoretical analyses reveal that, due to the microscopically rugged and low-adhesive nature of building blocks, the nanosamples can not only realize high-density nucleation but constrain growing condensates into suspended microdrops via the self-transport and/or self-expansion mode for subsequently self-propelled jumping, powered by coalescence-released excess surface energy. Consequently, our nanosample exhibits over 125% enhancement in DCHT coefficient. This work helps develop advanced heat-transfer materials and devices for efficient thermal management and energy utilization.

  6. High reproducibility and sensitivity of bifacial copper nanowire array for detection of glucose

    Directory of Open Access Journals (Sweden)

    Hanqing Zhang

    2017-06-01

    Full Text Available The ordered bifacial copper nanowire array (Cu BNWA was synthesized by a template assisted electrochemical deposition method. The morphology and structure of the as-prepared samples were investigated by field emission scanning electron microscope (FESEM and X-ray diffraction (XRD. The results show that the ordered Cu nanowire array with uniform geometrical dimensions covered both side of the Cu substrate. When used as the electrode for glucose detection, the minimum detectable concentration of glucose can be reached as low as 0.2 mM. Impressively, the sample still showed high sensitivity and stability for glucose detection after two months placement in ambient environment. These excellent performances of the Cu BNWA make it a promising non-enzyme glucose detection sensor for various applications.

  7. Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

    Directory of Open Access Journals (Sweden)

    Anne L. Schöffler

    2016-07-01

    Full Text Available A dinuclear N-heterocyclic carbene (NHC copper complex efficiently catalyzes azide–alkyne cycloaddition (CuAAC “click” reactions. The ancillary ligand comprises two 4,5-dimethyl-1,3-thiazol-2-ylidene units and an ethylene linker. The three-step preparation of the complex from commercially available starting compounds is more straightforward and cost-efficient than that of the previously described 1,2,4-triazol-5-ylidene derivatives. Kinetic experiments revealed its high catalytic CuAAC activity in organic solvents at room temperature. The activity increases upon addition of acetic acid, particularly for more acidic alkyne substrates. The modular catalyst design renders possible the exchange of N-heterocyclic carbene, linker, sacrificial ligand, and counter ion.

  8. Space Charge Behavior in Paper Insulation Induced by Copper Sulfide in High-Voltage Direct Current Power Transformers

    Directory of Open Access Journals (Sweden)

    Ruijin Liao

    2015-08-01

    Full Text Available The main insulation system in high-voltage direct current (HVDC transformer consists of oil-paper insulation. The formation of space charge in insulation paper is crucial for the dielectric strength. Unfortunately, space charge behavior changes because of the corrosive sulfur substance in oil. This paper presents the space charge behavior in insulation paper induced by copper sulfide generated by corrosive sulfur in insulation oil. Thermal aging tests of paper-wrapped copper strip called the pigtail model were conducted at 130 °C in laboratory. Scanning electron microscopy (SEM was used to observe the surface of copper and paper. Pulse electroacoustic (PEA and thermally stimulated current (TSC methods were used to obtain the space charge behavior in paper. Results showed that both maximum and total amount of space charge increased for the insulation paper contaminated by semi-conductor chemical substance copper sulfide. The space charge decay rate of contaminated paper was significantly enhanced after the polarization voltage was removed. The TSC results revealed that copper sulfide increased the trap density and lowered the shallow trap energy levels. These results contributed to charge transportation by de-trapping and trapping processes. This improved charge transportation could be the main reason for the decreased breakdown voltage of paper insulation material.

  9. Posttranslational regulation of copper transporters

    NARCIS (Netherlands)

    van den Berghe, P.V.E.

    2009-01-01

    The transition metal copper is an essential cofactor for many redox-active enzymes, but excessive copper can generate toxic reactive oxygen species. Copper homeostasis is maintained by highly conserved proteins, to balance copper uptake, distribution and export on the systemic and cellular level. Th

  10. Metal-biradical chains from a high-spin ligand and bis(hexafluoroacetylacetonato)copper(II).

    Science.gov (United States)

    Rajadurai, Chandrasekar; Enkelmann, Volker; Ikorskii, Vladimir; Ovcharenko, Victor I; Baumgarten, Martin

    2006-11-27

    The synthesis, X-ray crystal structure, and magnetic studies of a rare example of organic/inorganic spin hybrid clusters extended in infinite ladder-type chain [Cu(C5F6HO2)2]7(C35H35N5O4)2 ([Cu(hfac)2]7(pyacbisNN)2, 2) formed by the reaction of a high spin nitronylnitroxide biradical C35H35N5O4 (pyacbisNN, 1) and bis(hexafluroacetylacetonate)copper(II) = Cu(hfac)2 are described. Single-crystal X-ray structure analysis revealed the triclinic P1 space group of 2 with the following parameters: a = 10.6191(4) A, b = 19.6384(7) A, c = 21.941(9) A, alpha = 107.111(7) degrees, beta = 95.107(8) degrees, gamma = 94.208(0) degrees , Z = 2. Each repeating unit in 2 carries a centrosymmetric cyclic six spin and a linear five spin cluster with four different copper coordination environments having octahedral and square planar geometries. These clusters are interconnected to form infinite chains which are running along the crystallographic b axis. The magnetic measurements show nearly paramagnetic behavior with very small variations over a large temperature range. The magnetic properties are thus result of complex competitions of many weak ferro- and antiferromagnetic interactions, which appear as small deviations from quite linear mu(eff) vs T dependence at low temperature. At high temperature (300-14 K), antiferromagnetic behavior dominates a little, while at very low temperature (14-2 K), a small increase of mu(eff) was observed. The magnetic susceptibility data are described by the Curie-Weiss law [chi = C/(T - theta)] with the optimal parameters C = 4.32 +/- 0.01 emuK/mol and theta = - 0.6 +/- 0.3 K, where C is the Curie constant and theta is the Weiss temperature.

  11. 铜触头的高频钎焊%High-frequency brazing a copper contact

    Institute of Scientific and Technical Information of China (English)

    刘轶强; 张狄林

    2012-01-01

    叙述了焊接一种大面积铜触头由气体火焰钎焊改为高频钎焊的研究过程.通过更换钎料,设计合适的感应线圈,选用合适的焊接工艺参数,焊接出合格的产品.经肉眼观察、滚压实验、金相分析和扫描电镜的全面检测,触头的高频钎焊质量优良,符合设计要求.该研究对提高铜触头的焊接合格率,降低生产成本,节省焊接时间并大幅提高生产率,减轻劳动强度和改善劳动环境都有极大的价值.%This paper describes a large area of copper contact welding by the gas flame brazing replaced by high-frequency brazing process.By replacing the induction coil of solder,design appropriate, the appropriate choice of welding parameters, welding of qualified products. By the virual inspection ,rolling experiments, metallographic analysis and scanning electron microscope,a comprehensive inspection,the contact by high-frequency brazing has good quality and meets the design requirements. This study has great value for the company to improve the pass rate of welding of copper contacts,reduces production costs,saves the welding lime and dramatically increases productivity, reduces labor intensity and improves the working environment.

  12. Highly conductive copper nano/microparticles ink via flash light sintering for printed electronics

    Science.gov (United States)

    Joo, Sung-Jun; Hwang, Hyun-Jun; Kim, Hak-Sung

    2014-07-01

    In this study, the size effect of copper particles on the flash light sintering of copper (Cu) ink was investigated using Cu nanoparticles (20-50 nm diameter) and microparticles (2 μm diameter). Also, the mixed Cu nano-/micro-inks were fabricated, and the synergetic effects between the Cu nano-ink and micro-ink on flash light sintering were assessed. The ratio of nanoparticles to microparticles in Cu ink and the several flash light irradiation conditions (irradiation energy density, pulse number, on-time, and off-time) were optimized to obtain high conductivity of Cu films. In order to precisely monitor the milliseconds-long flash light sintering process, in situ monitoring of electrical resistance and temperature changes of Cu films was conducted during the flash light irradiation using a real-time Wheatstone bridge electrical circuit, thermocouple-based circuit, and a high-rate data acquisition system. Also, several microscopic and spectroscopic characterization techniques such as scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the flash light sintered Cu nano-/micro-films. In addition, the sheet resistance of Cu film was measured using a four-point probe method. This work revealed that the optimal ratio of nanoparticles to microparticles is 50:50 wt%, and the optimally fabricated and flash light sintered Cu nano-/micro-ink films have the lowest resistivity (80 μΩ cm) among nano-ink, micro-ink, or nano-micro mixed films.

  13. Precipitation behavior during thin slab thermomechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength structural steels: The effect on mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Jia, Z. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); O' Malley, R. [Nucor Steel Decatur, LLC Sheet Mill, 4301, Iverson Blvd., Trinity, AL 35673 (United States); Jansto, S.J. [CBMM-Reference Metals Company, 1000 Old Pond Road, Bridgeville, PA 15017 (United States)

    2011-11-15

    Highlights: {yields} Copper does not significantly influence toughness. {yields} Copper precipitation during aging occurs at dislocations. {yields} Precipitation of copper and carbides is mutually exclusive. - Abstract: We describe here the precipitation behavior of copper and fine-scale carbides during thermo-mechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength steels. During thermo-mechanical processing, precipitation of {epsilon}-copper occurs in polygonal ferrite and at the austenite-ferrite interface. In contrast, during isothermal aging, nucleation of {epsilon}-copper precipitation occurs at dislocations. In the three different chemistries investigated, the increase in strength associated with copper during aging results only in a small decrease in impact toughness, implying that copper precipitates do not seriously impair toughness, and can be considered as a viable strengthening element in microalloyed steels. Precipitation of fine-scale niobium carbides occurs extensively at dislocations and within ferrite matrix together with vanadium carbides. In the presence of titanium, titanium carbides act as a nucleus for niobium carbide formation. Irrespective of the nature of carbides, copper precipitates and carbides are mutually exclusive.

  14. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.P. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Duarte, G.W. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Research Group in Technology and Information, Centro Universitário Barriga Verde (UNIBAVE), Santa Catarina, SC (Brazil); Caldart, C. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Kniess, C.T. [Post-Graduate Program in Professional Master in Management, Universidade Nove de Julho, São Paulo, SP (Brazil); Montedo, O.R.K.; Rocha, M.R. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Riella, H.G. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduate Program in Environmental Science, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil); Post-Graduate Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil)

    2015-11-15

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound.

  15. Highly sensitive determination of copper in HeLa cell using capillary electrophoresis combined with a simple cell extraction treatment.

    Science.gov (United States)

    Meng, Lingchen; Fang, Ziyuan; Lin, Jian; Li, Meixian; Zhu, Zhiwei

    2014-04-01

    A new separation system of capillary electrophoresis (CE1) for the highly sensitive determination of copper was established by using ethylenediaminetetraacetic acid (EDTA) as a complexing agent and employing cetyltrimethylammonium chloride (CTAC) as a capillary inner wall modifier. Benefitted from the combination of field-enhanced sample injection (FESI) method, a limit of detection (LOD) of 2.7 nM was obtained, which was much lower than that of the conventional methods. This made it possible to determine trace copper in HeLa cell only by a simple cell extraction (CE2) treatment. Two copper-extraction methods-acid-hydrolysis and freeze-thaw-were compared. Limited by the requirement of low ion strength in FESI, only the extract using freeze-thaw could be successfully applied in the determination. The effectiveness assessment of this CE(2)-FESI method was adopted by inductively coupled plasma-atomic emission spectrometry (ICP-AES) as a gold standard.

  16. High-performance Copper Alloy QBD-6%高性能铜合金QBD-6

    Institute of Scientific and Technical Information of China (English)

    曾力维; 张舟逸; 蒋中华

    2015-01-01

    Use electromagnetic stirring, horizontal continuous casting to break casting structure and refine casting the precipitates "Ni - P" compounds by high temperature annealing. After 20 finished rolling mills, the production of QBD - 6 high-performance copper alloy plate strips has high strength, high elasticity, high conductivity, high finish and other characteristics which can replace imported alloy, such as: MF202, CAC5 and some low-intensity C7025. This can be successfully applied to the lead frame materials, connectors, terminals, and motor brush components in power tools.%采用电磁搅拌水平连铸,破碎铸造组织并通过高温退火细化铸造组织中的析出物"Ni-P"化合物,经过20辊轧机的成品轧制,生产的QBD-6高性能铜合金板带材具有高强度、高弹性、高导电和高光洁度等特性,可替代进口合金,如:M F202、C A C5以及部分低强度的C7025.成功应用于引线框架材料、连接器、端子以及电动工具中的电机电刷部件.

  17. Structural characterization of a high affinity mononuclear site in the copper(II)-α-synuclein complex.

    Science.gov (United States)

    Bortolus, Marco; Bisaglia, Marco; Zoleo, Alfonso; Fittipaldi, Maria; Benfatto, Maurizio; Bubacco, Luigi; Maniero, Anna Lisa

    2010-12-29

    Human α-Synuclein (aS), a 140 amino acid protein, is the main constituent of Lewy bodies, the cytoplasmatic deposits found in the brains of Parkinson's disease patients, where it is present in an aggregated, fibrillar form. Recent studies have shown that aS is a metal binding protein. Moreover, heavy metal ions, in particular divalent copper, accelerate the aggregation process of the protein. In this work, we investigated the high affinity binding mode of truncated aS (1-99) (aS99) with Cu(II), in a stoichiometric ratio, to elucidate the residues involved in the binding site and the role of copper ions in the protein oligomerization. We used Electron Paramagnetic Resonance spectroscopy on the Cu(II)-aS99 complex at pH 6.5, performing both multifrequency continuous wave experiments and pulsed experiments at X-band. The comparison of 9.5 and 95 GHz data showed that at this pH only one binding mode is present. To identify the nature of the ligands, we performed Electron Spin Echo Envelope Modulation, Hyperfine Sublevel Correlation Spectroscopy, and pulsed Davies Electron-Nuclear Double Resonance (Davies-ENDOR) experiments. We determined that the EPR parameters are typical of a type-II copper complex, in a slightly distorted square planar geometry. Combining the results from the different pulsed techniques, we obtained that the equatorial coordination is {N(Im), N(-), H(2)O, O}, where N(im) is the imino nitrogen of His50, N(-) a deprotonated amido backbone nitrogen that we attribute to His50, H(2)O an exchangeable water molecule, and O an unidentified oxygen ligand. Moreover, we propose that the free amino terminus (Met1) participates in the complex as an axial ligand. The MXAN analysis of the XAS k-edge absorption data allowed us to independently validate the structural features proposed on the basis of the magnetic parameters of the Cu(II)-aS99 complex and then to further refine the quality of the proposed structural model.

  18. Stability of dislocation structures in copper towards stress relaxation investigated by high angular resolution 3D X-ray diffraction

    DEFF Research Database (Denmark)

    Jakobsen, Bo; Poulsen, Henning Friis; Lienert, Ulrich

    2009-01-01

    A 300 µm thick tensile specimen of OFHC copper is subjected to a tensile loading sequence and deformed to a maximal strain of 3.11%. Using the novel three-dimensional X-ray diffraction method High angular resolution 3DXRD', the evolution of the microstructure within a deeply embedded grain is cha...

  19. Three-dimensional porous hollow fibre copper electrodes for efficient and high-rate electrochemical carbon dioxide reduction

    NARCIS (Netherlands)

    Kas, Recep; Hummadi, Khalid Khazzal; Kortlever, Ruud; Wit, de Patrick; Milbrat, Alexander; Luiten-Olieman, Mieke W.J.; Benes, Nieck E.; Koper, Marc T.M.; Mul, Guido

    2016-01-01

    Aqueous-phase electrochemical reduction of carbon dioxide requires an active, earth-abundant electrocatalyst, as well as highly efficient mass transport. Here we report the design of a porous hollow fibre copper electrode with a compact three-dimensional geometry, which provides a large area, three-

  20. Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils.

    Science.gov (United States)

    Christiansen, Karen S; Borggaard, Ole K; Holm, Peter E; Vijver, Martina G; Hauschild, Michael Z; Peijnenburg, Willie J G M

    2015-04-01

    Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC50(Cu(2+)), i.e., the negative logarithm of the EC50(Cu(2+)) activity to plant growth. The determined pEC50(Cu(2+)) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87% of the pEC50(Cu(2+)) variation according to the simple equation: pEC50(Cu(2+)) = 0.98 × pH + 345 × [DOC] - 0.27. Other soil characteristics, including the base cation concentrations (Na(+), K(+), Ca(2+), Mg(2+)), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu(2+)). Consequently, Cu toxicity, expressed as the negative log of the Cu(2+) activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.

  1. Staining of dentin from amalgam corrosion is induced by demineralization

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; van der Hoorn, Wietske; Huysmans, Marie-Charlotte D. N. J. M.; Roeters, Joost F. M.; Kleverlaan, Cornelis J.; Feilzer, Albert J.; Ozcan, Mutlu

    2013-01-01

    Purpose: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. Methods: Sound human molars (n= 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n=

  2. BACTERIAL ADHESION TO DENTAL AMALGAM AND 3 RESIN COMPOSITES

    NARCIS (Netherlands)

    SULJAK, JP; REID, G; WOOD, SM; MCCONNELL, RJ; VANDERMEI, HC; BUSSCHER, HJ

    Objectives: The ability of three oral bacteria to adhere to hydrophobic amalgam (water contact angle 60 degrees) and hydrophobic resin composites (Prisma-AP.H 56 degrees, Herculite XRV 82 degrees and Z100 89 degrees) was compared using an in vitro assay. Methods and results: Following preincubation

  3. Staining of dentin from amalgam corrosion is induced by demineralization

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; van der Hoorn, Wietske; Huysmans, Marie-Charlotte D. N. J. M.; Roeters, Joost F. M.; Kleverlaan, Cornelis J.; Feilzer, Albert J.; Ozcan, Mutlu

    2013-01-01

    Purpose: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. Methods: Sound human molars (n= 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n=

  4. Test of Picture-Text Amalgams in Procedural Texts.

    Science.gov (United States)

    Stone, David Edey

    Designed to assess how people read and comprehend information presented in picture-text amalgams in procedural texts, this instrument presents various combinations of text information and illustrative information on slides. Subjects are assigned to one of four conditions and directed to follow the instructions presented on the slides. Videotapes…

  5. Amalgam and ART restorations in children: a controlled clinical trial

    NARCIS (Netherlands)

    Amorim, R.G. de; Leal, S.C.; Mulder, J.; Creugers, N.H.J.; Frencken, J.E.F.M.

    2014-01-01

    OBJECTIVES: The aims of this study were to compare 2-year cumulative survival rates of amalgam and atraumatic restorative treatment (ART) restorations in primary molars and to investigate the determinants of the survival rate of restorations. MATERIALS AND METHODS: A controlled clinical trial using

  6. Amalgams of Rank 2 and Characteristic 3 Involving M11

    Institute of Scientific and Technical Information of China (English)

    黄建华; 李慧陵

    1994-01-01

    In this paper we investigate the amalgams (M11,X) of rank 2 and characteristic 3,where X is a group of Lie type of rank 1 or permutation group of low rank,and give a characterization of the 3 local subgroups of the finite sporadic groups Co3 of Ly and Suz.

  7. Staining of dentin from amalgam corrosion is induced by demineralization

    NARCIS (Netherlands)

    Scholtanus, J.D.; van der Hoorn, W.; Özcan, M.; Huysmans, M.C.D.N.J.M.; Roeters, J.F.M.; Kleverlaan, C.J.; Feilzer, A.J.

    2013-01-01

    PURPOSE: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. METHODS: Sound human molars (n = 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n

  8. BACTERIAL ADHESION TO DENTAL AMALGAM AND 3 RESIN COMPOSITES

    NARCIS (Netherlands)

    SULJAK, JP; REID, G; WOOD, SM; MCCONNELL, RJ; VANDERMEI, HC; BUSSCHER, HJ

    1995-01-01

    Objectives: The ability of three oral bacteria to adhere to hydrophobic amalgam (water contact angle 60 degrees) and hydrophobic resin composites (Prisma-AP.H 56 degrees, Herculite XRV 82 degrees and Z100 89 degrees) was compared using an in vitro assay. Methods and results: Following preincubation

  9. Influence of cavity depth on marginal degradation of amalgam restorations.

    Science.gov (United States)

    Jokstad, A

    1991-04-01

    In a 5-year clinical trial it was observed that the marginal degradation of class-II amalgam restorations could be related to the bulk of the restoration. The association between the occlusal cavity depth and the marginal degradation was observed after 6 months and varied for the different types of alloy. Ridit scores of the marginal degradation were correlated to various indices of the cavity sizes, to assess the possible reason for this association. The possibilities of the relationship being an indirect effect caused by longer condensation times or by poorer condensation due to the use of larger condenser sizes were rejected. Furthermore, the possibility that the association was the result of potential buildup of stresses on the restoration margins caused by flexible cusps and axial walls was not apparent. A possible mechanism may be that marginal degradation is the result of short-term or long-term expansion, or even extrusion of amalgam. Expansion may theoretically be caused over short periods by temperature changes or over long periods by corrosion or phase shifts in the amalgam. The theory does not exclude the role of creep or corrosion and may furthermore explain the lack of correlation between in-vitro tests and in-vivo performance of amalgam restorations.

  10. The problem of motivating teaching staff in a complex amalgamation.

    Science.gov (United States)

    Kenrick, M A

    1993-09-01

    This paper addresses some of the problems brought about by the merger of a number of schools of nursing into a new complex amalgamation. A very real concern in the new colleges of nursing and midwifery in the United Kingdom is the effect of amalgamation on management systems and staff morale. The main focus of this paper is the motivation of staff during this time of change. There is currently a lack of security amongst staff and in many instances the personal job satisfaction of nurse teachers and managers of nurse education has been reduced, which has made the task of motivating staff difficult. Hence, two major theories of motivation and the implications of these theories for managers of nurse education are discussed. The criteria used for the selection of managers within the new colleges, leadership styles and organizational structures are reviewed. The amalgamations have brought about affiliation with higher-education institutions. Some problems associated with these mergers and the effects on the motivation of staff both within the higher-education institutions and the nursing colleges are outlined. Strategies for overcoming some of the problems are proposed including job enlargement, job enrichment, potential achievement rewards and the use of individual performance reviews which may be useful for assessing the ability of all staff, including managers, in the new amalgamations.

  11. Staining of dentin from amalgam corrosion is induced by demineralization

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; van der Hoorn, Wietske; Huysmans, Marie-Charlotte D. N. J. M.; Roeters, Joost F. M.; Kleverlaan, Cornelis J.; Feilzer, Albert J.; Ozcan, Mutlu

    Purpose: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. Methods: Sound human molars (n= 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n=

  12. High-temperature interface superconductivity between metallic and insulating copper oxides.

    Science.gov (United States)

    Gozar, A; Logvenov, G; Kourkoutis, L Fitting; Bollinger, A T; Giannuzzi, L A; Muller, D A; Bozovic, I

    2008-10-09

    The realization of high-transition-temperature (high-T(c)) superconductivity confined to nanometre-sized interfaces has been a long-standing goal because of potential applications and the opportunity to study quantum phenomena in reduced dimensions. This has been, however, a challenging target: in conventional metals, the high electron density restricts interface effects (such as carrier depletion or accumulation) to a region much narrower than the coherence length, which is the scale necessary for superconductivity to occur. By contrast, in copper oxides the carrier density is low whereas T(c) is high and the coherence length very short, which provides an opportunity-but at a price: the interface must be atomically perfect. Here we report superconductivity in bilayers consisting of an insulator (La(2)CuO(4)) and a metal (La(1.55)Sr(0.45)CuO(4)), neither of which is superconducting in isolation. In these bilayers, T(c) is either approximately 15 K or approximately 30 K, depending on the layering sequence. This highly robust phenomenon is confined within 2-3 nm of the interface. If such a bilayer is exposed to ozone, T(c) exceeds 50 K, and this enhanced superconductivity is also shown to originate from an interface layer about 1-2 unit cells thick. Enhancement of T(c) in bilayer systems was observed previously but the essential role of the interface was not recognized at the time.

  13. [Copper IUDs (author's transl)].

    Science.gov (United States)

    Thiery, M

    1983-10-01

    for as long as 20 years. Shorter and smaller versions of standard copper IUDs have been tested as they permit easier insertion, but high rates of pregnancy, expulsion, and removal have prevented their wider use. The discovery that the size of the uterine cavity is more important than its length has prompted the development of some promising uterine measuring instruments. Attempts to develop a device appropriate for postpartum use have been disappointing, and expulsion rates remain high. A few promising new forms of copper IUDs have been developed but not yet tested clinically.

  14. High-average-power high-beam-quality vis-UV sources based on kinetically enhanced copper vapor lasers

    Science.gov (United States)

    Brown, Daniel J. W.; Withford, Michael J.; Carman, Robert J.; Mildren, Richard P.; Piper, James A.

    2000-04-01

    Investigations of the factors that limit average power scaling of elemental copper vapor lasers (CVLs) have demonstrated that decay of the electron density in the interpulse period is critical in restricting pulse repetition rate and laser aperture scaling. We have recently developed the 'kinetic enhancement' (or KE) technique to overcome these limitations, whereby optimal plasma conditions are engineered using low concentrations of HCl/H2 additive gases in the Ne buffer. Dissociative electron attachment of HCl and subsequent mutual neutralization of Cl- and Cu+ promote rapid plasma relaxation and fast recovery of Cu densities, permitting operation at elevated Cu densities and pulse rates for given apertures. Using this approach, we have demonstrated increases in output power and efficiency of a factor of 2 or higher over conventional CVLs of the same size. For a 38 mm- bore KE-CVL, output powers up to 150 W have been achieved at 22 kHz, corresponding to record specific powers (80 mW/cm3) for such a 'small/medium-scale' device. In addition, kinetic enhancement significantly extends the gain duration and restores gain on-axis, even for high pulse rates, thereby promoting substantial increases (5 - 10x) in high- beam-quality power levels when operating with unstable resonators. This has enabled us to achieve much higher powers in second-harmonic generation from the visible copper laser output to the ultraviolet (e.g. 5 W at 255 nm from a small- scale KE-CVL). Our approach to developing KE-CVLs including computer modeling and experimental studies will be reviewed, and most recent results in pulse rate scaling and scaling of high-beam-quality power using oscillator-amplifier configurations, will be presented.

  15. Management of large radicular cyst associated with amalgam particles in cystic lining.

    Science.gov (United States)

    Borkar, Swati A; Dhupar, Vikas; Gadkar, Abhilasha M; Nivedita, C K V S

    2016-01-01

    The failure of amalgam retrofilling and presence of an associated cystic lesion makes surgical endodontic intervention inevitable. Amalgam retrofilling can also give rise to mucoperiosteal tattoo formation and allow incorporation of amalgam particles in the cystic lining. Such a finding has not yet been reported in the endodontic literature. This case report describes the successful endodontic management of a large radicular cyst associated with failed amalgam retrofilling, mucoperiosteal tattoo and amalgam particles dispersed in the epithelial cystic lining. All four mandibular incisors associated with the lesion presented with Weine Type II canal anatomy. The follow-up revealed clinical and radiographic signs of healing.

  16. Management of large radicular cyst associated with amalgam particles in cystic lining

    Science.gov (United States)

    Borkar, Swati A.; Dhupar, Vikas; Gadkar, Abhilasha M.; Nivedita, C.K.V.S.

    2016-01-01

    The failure of amalgam retrofilling and presence of an associated cystic lesion makes surgical endodontic intervention inevitable. Amalgam retrofilling can also give rise to mucoperiosteal tattoo formation and allow incorporation of amalgam particles in the cystic lining. Such a finding has not yet been reported in the endodontic literature. This case report describes the successful endodontic management of a large radicular cyst associated with failed amalgam retrofilling, mucoperiosteal tattoo and amalgam particles dispersed in the epithelial cystic lining. All four mandibular incisors associated with the lesion presented with Weine Type II canal anatomy. The follow-up revealed clinical and radiographic signs of healing. PMID:27217645

  17. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    Directory of Open Access Journals (Sweden)

    Richard C. Petersen

    2016-01-01

    Full Text Available Photocure fiber-reinforced composites (FRCs with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p<1.1×10-5. Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity.

  18. Compact X-ray Source using a High Repetition Rate Laser and Copper Linac

    CERN Document Server

    Graves, W S; Brown, P; Carbajo, S; Dolgashev, V; Hong, K -H; Ihloff, E; Khaykovich, B; Lin, H; Murari, K; Nanni, E A; Resta, G; Tantawi, S; Zapata, L E; Kärtner, F X; Moncton, D E

    2014-01-01

    A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standing-wave linac and RF photoinjector powered by a single ultrastable RF transmitter at x-band RF frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The 100 kHz repetition rate is orders of magnitude beyond existing high brightness copper linacs. The entire accelerator is approximately 1 meter long and produces hard x-rays tunable over a wide range of photon energies. The colliding laser is a Yb:YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for m...

  19. Investigation into high-frequency-vibration assisted micro-blanking of pure copper foils

    Directory of Open Access Journals (Sweden)

    Wang Chunju

    2015-01-01

    Full Text Available The difficulties encountered during the manufacture of microparts are often associated with size effects relating to material, process and tooling. Utilizing acoustoplastic softening, achieved through a high-frequency vibration assisted micro-blanking process, was introduced to improve the surface finish in micro-blanking. A frequency of 1.0 kHz was chosen to activate the longitudinal vibration mode of the horn tip, using a piezoelectric actuator. A square hole with dimensions of 0.5 mm × 0.5 mm was made, successfully, from a commercial rolled T2 copper foil with 100 μm in thickness. It was found that the maximum blanking force could be reduced by 5% through utilizing the high-frequency vibration. Proportion of the smooth, burnished area in the cut cross-section increases with an increase of the plasticity to fracture, under the high-frequency vibration, which suggests that the vibration introduced is helpful for inhibiting evolution of the crack due to its acoustoplastic softening effect. During blanking, roughness of the burnished surface could be reduced by increasing the vibration amplitude of the punch, which played a role as surface polishing. The results obtained suggest that the high-frequency vibration can be adopted in micro-blanking in order to improve quality of the microparts.

  20. 低砷高锑阳极的铜电解生产%Low Arsenic High Antimony Copper Anode Copper Electrolysis Production

    Institute of Scientific and Technical Information of China (English)

    杨洪光

    2012-01-01

    介绍了我国北方某电解铜厂,在很长一段时间内,采购的阳极含砷较低而含锑较高。针对这种阳极板,采取了合理控制电解液成分、合理选用添加剂种类和控制用量、提高电解液温度、改变电解液循环方式、由常规电解改为周期反向电解等技术措施和完善操作方法,使电铜的合格率达到了100%。%A electrolytic copper factory in north,in a long time,purchased the anode arsenic low and antimony high.In this kind of YangJiBan,through taking reasonable control electrolyte composition,reasonable choice of additive type and dosage of control,improving the electrolyte temperature,changing the electrolyte cycle way,by conventional electrolysis to cycle reverse electrolysis,etc,such as technical measures and perfect operation methods,the qualified rate of the copper was made to reach 100%.

  1. Maternal-fetal distribution of mercury ( sup 203 Hg) released from dental amalgam fillings

    Energy Technology Data Exchange (ETDEWEB)

    Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L. (Univ. of Calgary, Alberta (Canada))

    1990-04-01

    In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.

  2. A prospective study of prenatal mercury exposure from maternal dental amalgams and autism severity.

    Science.gov (United States)

    Geier, David A; Kern, Janet K; Geier, Mark R

    2009-01-01

    Dental amalgams containing 50% mercury (Hg) have been used in dentistry for the last 150 years, and Hg exposure during key developmental periods was associated with autism spectrum disorders (ASDs). This study examined increased Hg exposure from maternal dental amalgams during pregnancy among 100 qualifying participants born between 1990-1999 and diagnosed with DSM-IV autism (severe) or ASD (mild). Logistic regression analysis (age, gender, race, and region of residency adjusted) by quintile of maternal dental amalgams during pregnancy revealed the ratio of autism:ASD (severe:mild) were about 1 (no effect) for or =6 amalgams. Subjects with > or =6 amalgams were 3.2-fold significantly more likely to be diagnosed with autism (severe) in comparison to ASD (mild) than subjects with < or =5 amalgams. Dental amalgam policies should consider Hg exposure in women before and during the child-bearing age and the possibility of subsequent fetal exposure and adverse outcomes.

  3. A new copper containing MALDI matrix that yields high abundances of [peptide + Cu]+ ions.

    Science.gov (United States)

    Wu, Zhaoxiang; Fernandez-Lima, Francisco A; Perez, Lisa M; Russell, David H

    2009-07-01

    The dinuclear copper complex (alpha-cyano-4-hydroxycinnamic acid (CHCA) copper salt (CHCA)(4)Cu(2)), synthesized by reacting CHCA with copper oxide (CuO), yields increased abundances of [M + xCu - (x-1)H](+) (x = 1-6) ions when used as a matrix for matrix-assisted laser desorption ionization (355 nm Nd:YAG laser). The yield of [M + xCu - (x-1)H](+) (x = 1 to approximately 6) ion is much greater than that obtained by mixing peptides with copper salts or directly depositing peptides onto oxidized copper surfaces. The increased ion yields for [M + xCu - (x-1)H](+) facilitate studies of biologically important copper binding peptides. For example, using this matrix we have investigated site-specific copper binding of several peptides using fragmentation chemistry of [M + Cu](+) and [M + 2Cu - H](+) ions. The fragmentation studies reveal interesting insight on Cu binding preferences for basic amino acids. Most notable is the fact that the binding of a single Cu(+) ion and two Cu(+) ions are quite different, and these differences are explained in terms of intramolecular interactions of the peptide-Cu ionic complex.

  4. Investigation of high-k yttrium copper titanate thin films as alternative gate dielectrics

    Science.gov (United States)

    Grazia Monteduro, Anna; Ameer, Zoobia; Rizzato, Silvia; Martino, Maurizio; Caricato, Anna Paola; Tasco, Vittorianna; Chaitanya Lekshmi, Indira; Hazarika, Abhijit; Choudhury, Debraj; Sarma, D. D.; Maruccio, Giuseppe

    2016-10-01

    Nearly amorphous high-k yttrium copper titanate thin films deposited by laser ablation were investigated in both metal-oxide-semiconductor (MOS) and metal-insulator-metal (MIM) junctions in order to assess the potentialities of this material as a gate oxide. The trend of dielectric parameters with film deposition shows a wide tunability for the dielectric constant and AC conductivity, with a remarkably high dielectric constant value of up to 95 for the thick films and conductivity as low as 6  ×  10-10 S cm-1 for the thin films deposited at high oxygen pressure. The AC conductivity analysis points out a decrease in the conductivity, indicating the formation of a blocking interface layer, probably due to partial oxidation of the thin films during cool-down in an oxygen atmosphere. Topography and surface potential characterizations highlight differences in the thin film microstructure as a function of the deposition conditions; these differences seem to affect their electrical properties.

  5. The properties of high-energy milled pre-alloyed copper powders containing 1 wt. % Al

    Directory of Open Access Journals (Sweden)

    VISESLAVA RAJKOVIC

    2007-01-01

    Full Text Available The microstructural and morphological changes of inert gas atomized pre-alloyed Cu-1 wt. % Al powders subjected to hith-energy milling were studied. The microhardness of hot-pressed compacts was measured as a function of milling time. The thermal stability during exposure at 800 °C and the electrical conductivity of compacts were also examined. During the high-energy milling, severe deformation led to refinement of the powder particle grain size (from 550 nm to about 55 nm and a decrease in the lattice parameter (0.10 %, indicating precipitation of aluminium from the copper matrix. The microhardness of compacts obtained from 5 h-milled powders was 2160 MPa. After exposure at 800 °C for 5 h, these compacts still exhibited a high microhardness value (1325 MPa, indicating good thermal stability. The increase of microhardness and good thermal stability is attributed to the small grain size (270 and 390 nm before and after high temperature exposure, respectively. The room temperature electrical conductivity of compacts processed from 5 h-milled powder was 79 % IACS.

  6. Facile preparation of carbon wrapped copper telluride nanowires as high performance anodes for sodium and lithium ion batteries

    Science.gov (United States)

    Yu, Hong; Yang, Jun; Geng, Hongbo; Chao Li, Cheng

    2017-04-01

    Uniform carbon wrapped copper telluride nanowires were successfully prepared by using an in situ conversion reaction. The length of these nanowires is up to several micrometers and the width is around 30–40 nm. The unique one dimensional structure and the presence of conformal carbon coating of copper telluride greatly accommodate the large volumetric changes during cycling, significantly increase the electrical conductivity and reduce charge transfer resistance. The copper telluride nanowires show promising performance in a lithium ion battery with a discharge capacity of 130.2 mA h g‑1 at a high current density of 6.0 A g‑1 (26.74 C) and a stable cycling performance of 673.3 mA h g‑1 during the 60th cycle at 100 mA g‑1. When evaluated as anode material for a sodium ion battery, the copper telluride nanowires deliver a reversible capacity of 68.1 mA h g‑1 at 1.0 A g‑1 (∼4.46 C) and have a high capacity retention of 177.5 mA h g‑1 during the 500th cycle at 100 mA g‑1.

  7. Deformation and annealing behavior of heavily drawn oxygen-free high-conductivity (OFHC) copper

    Science.gov (United States)

    Waryoba, Daudi Rigenda

    Conductor wires used in pulsed high-field magnets require metallic materials with a beneficial combination of high mechanical strength to resist the Lorentz forces and high electrical conductivity to limit temperature excursions due to Joule heating. To achieve the required strength, most conductors are fabricated from microcomposite materials using the work hardening effect after heavy cold deformation such as wire drawing. Since the microstructure and texture of these microcomposites are complex, a detailed systematic study of these materials requires a separate study of the individual phases. This work presents a comprehensive study of the microstructure and microtexture evolution during deformation, and subsequent annealing of heavily deformed OFHC copper wires. Analytical tools used for investigation include optical microscopy, scanning electron microscopy (SEM), orientation-imaging microscopy (OIM) in SEM, and transmission electron microscopy (TEM). Mechanical properties were evaluated by tensile and microhardness testing. Some of the key features of the as-drawn wire are elongated grain size and shear bands. The intensity of the shear bands increased with strain. The ultimate tensile strength (UTS) and the microhardness of the heavily cold-drawn copper wires increased with strain, reached a saturation point and dropped at higher deformation strain. Deformation did not significantly alter the electrical conductivity of the wires. Deformed and recovered microstructures were characterized by a strong+weak duplex fiber texture. Nucleation of recrystallized grains occurred at shear bands and resulted in randomization of texture. On the other hand, recrystallization produced a strong+weak, which later changed to a fiber texture during abnormal grain growth. A detailed analysis showed that recrystallization was a growth-controlled mechanism, and proceeds from the outer surface to the core. Interestingly, secondary recrystallization was observed to proceed from the

  8. [Copper and the human body].

    Science.gov (United States)

    Krízek, M; Senft, V; Motán, J

    1997-11-19

    Copper is one of the essential trace elements. It is part of a number of enzymes. Deficiency of the element is manifested by impaired haematopoesis, bone metabolism, disorders of the digestive, cardiovascular and nervous system. Deficiency occurs in particular in patients suffering from malnutrition, malabsorption, great copper losses during administration of penicillamine. Sporadically copper intoxications are described (suicidal intentions or accidental ingestion of beverages with a high copper content). Acute exposure to copper containing dust is manifested by metal fume fever. Copper salts can produce local inflammations. Wilson's disease is associated with inborn impaired copper metabolism. In dialyzed patients possible contaminations of the dialyzate with copper must be foreseen as well as the possible release of copper from some dialyzation membranes. With the increasing amount of copper in the environment it is essential to monitor the contamination of the environment.

  9. Mercury in dental amalgam: Are our health care workers at risk?

    Science.gov (United States)

    Sahani, M; Sulaiman, N S; Tan, B S; Yahya, N A; Anual, Z F; Mahiyuddin, W R Wan; Khan, M F; Muttalib, K A

    2016-11-01

    Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann-Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann-Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612-64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

  10. Electrical wire explosion process of copper/silver hybrid nano-particle ink and its sintering via flash white light to achieve high electrical conductivity

    Science.gov (United States)

    Chung, Wan-Ho; Hwang, Yeon-Taek; Lee, Seung-Hyun; Kim, Hak-Sung

    2016-05-01

    In this work, combined silver/copper nanoparticles were fabricated by the electrical explosion of a metal wire. In this method, a high electrical current passes through the metal wire with a high voltage. Consequently, the metal wire evaporates and metal nanoparticles are formed. The diameters of the silver and copper nanoparticles were controlled by changing the voltage conditions. The fabricated silver and copper nano-inks were printed on a flexible polyimide (PI) substrate and sintered at room temperature via a flash light process, using a xenon lamp and varying the light energy. The microstructures of the sintered silver and copper films were observed using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). To investigate the crystal phases of the flash-light-sintered silver and copper films, x-ray diffraction (XRD) was performed. The absorption wavelengths of the silver and copper nano-inks were measured using ultraviolet-visible spectroscopy (UV-vis). Furthermore, the resistivity of the sintered silver and copper films was measured using the four-point probe method and an alpha step. As a result, the fabricated Cu/Ag film shows a high electrical conductivity (4.06 μΩcm), which is comparable to the resistivity of bulk copper (1.68 μΩcm). In addition, the fabricated Cu/Ag nanoparticle film shows superior oxidation stability compared to the Cu nanoparticle film.

  11. Electrical wire explosion process of copper/silver hybrid nano-particle ink and its sintering via flash white light to achieve high electrical conductivity.

    Science.gov (United States)

    Chung, Wan-Ho; Hwang, Yeon-Taek; Lee, Seung-Hyun; Kim, Hak-Sung

    2016-05-20

    In this work, combined silver/copper nanoparticles were fabricated by the electrical explosion of a metal wire. In this method, a high electrical current passes through the metal wire with a high voltage. Consequently, the metal wire evaporates and metal nanoparticles are formed. The diameters of the silver and copper nanoparticles were controlled by changing the voltage conditions. The fabricated silver and copper nano-inks were printed on a flexible polyimide (PI) substrate and sintered at room temperature via a flash light process, using a xenon lamp and varying the light energy. The microstructures of the sintered silver and copper films were observed using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). To investigate the crystal phases of the flash-light-sintered silver and copper films, x-ray diffraction (XRD) was performed. The absorption wavelengths of the silver and copper nano-inks were measured using ultraviolet-visible spectroscopy (UV-vis). Furthermore, the resistivity of the sintered silver and copper films was measured using the four-point probe method and an alpha step. As a result, the fabricated Cu/Ag film shows a high electrical conductivity (4.06 μΩcm), which is comparable to the resistivity of bulk copper (1.68 μΩcm). In addition, the fabricated Cu/Ag nanoparticle film shows superior oxidation stability compared to the Cu nanoparticle film.

  12. Normal-state nodal electronic structure in underdoped high-Tc copper oxides.

    Science.gov (United States)

    Sebastian, Suchitra E; Harrison, N; Balakirev, F F; Altarawneh, M M; Goddard, P A; Liang, Ruixing; Bonn, D A; Hardy, W N; Lonzarich, G G

    2014-07-03

    An outstanding problem in the field of high-transition-temperature (high-Tc) superconductivity is the identification of the normal state out of which superconductivity emerges in the mysterious underdoped regime. The normal state uncomplicated by thermal fluctuations can be studied using applied magnetic fields that are sufficiently strong to suppress long-range superconductivity at low temperatures. Proposals in which the normal ground state is characterized by small Fermi surface pockets that exist in the absence of symmetry breaking have been superseded by models based on the existence of a superlattice that breaks the translational symmetry of the underlying lattice. Recently, a charge superlattice model that positions a small electron-like Fermi pocket in the vicinity of the nodes (where the superconducting gap is minimum) has been proposed as a replacement for the prevalent superlattice models that position the Fermi pocket in the vicinity of the pseudogap at the antinodes (where the superconducting gap is maximum). Although some ingredients of symmetry breaking have been recently revealed by crystallographic studies, their relevance to the electronic structure remains unresolved. Here we report angle-resolved quantum oscillation measurements in the underdoped copper oxide YBa2Cu3O6 + x. These measurements reveal a normal ground state comprising electron-like Fermi surface pockets located in the vicinity of the nodes, and also point to an underlying superlattice structure of low frequency and long wavelength with features in common with the charge order identified recently by complementary spectroscopic techniques.

  13. Bio-inspired multistructured conical copper wires for highly efficient liquid manipulation.

    Science.gov (United States)

    Wang, Qianbin; Meng, Qingan; Chen, Ming; Liu, Huan; Jiang, Lei

    2014-09-23

    Animal hairs are typical structured conical fibers ubiquitous in natural system that enable the manipulation of low viscosity liquid in a well-controlled manner, which serves as the fundamental structure in Chinese brush for ink delivery in a controllable manner. Here, drawing inspiration from these structure, we developed a dynamic electrochemical method that enables fabricating the anisotropic multiscale structured conical copper wire (SCCW) with controllable conicity and surface morphology. The as-prepared SCCW exhibits a unique ability for manipulating liquid with significantly high efficiency, and over 428 times greater than its own volume of liquid could be therefore operated. We propose that the boundary condition of the dynamic liquid balance behavior on conical fibers, namely, steady holding of liquid droplet at the tip region of the SCCW, makes it an excellent fibrous medium to manipulate liquid. Moreover, we demonstrate that the titling angle of the SCCW can also affect its efficiency of liquid manipulation by virtue of its mechanical rigidity, which is hardly realized by flexible natural hairs. We envision that the bio-inspired SCCW could give inspiration in designing materials and devices to manipulate liquid in a more controllable way and with high efficiency.

  14. Paths and determinants for Penicillium janthinellum to resist low and high copper.

    Science.gov (United States)

    Xu, Jian; Chen, Guo-Li; Sun, Xue-Zhe; Fan, Xian-Wei; You-Zhi, Li

    2015-08-12

    Copper (Cu) tolerance was well understood in fungi yeasts but not in filamentous fungi. Filamentous fungi are eukaryotes but unlike eukaryotic fungi yeasts, which are a collection of various fungi that are maybe classified into different taxa but all characterized by growth as filamentous hyphae cells and with a complex morphology. The current knowledge of Cu resistance of filamentous fungi is still fragmental and therefore needs to be bridged. In this study, we characterized Cu resistance of Penicillium janthinellum strain GXCR and its Cu-resistance-decreasing mutants (EC-6 and UC-8), and conducted sequencing of a total of 6 transcriptomes from wild-type GXCR and mutant EC-6 grown under control and external Cu. Taken all the results together, Cu effects on the basal metabolism were directed to solute transport by two superfamilies of solute carrier and major facilitator, the buffering free CoA and Acyl-CoA pool in the peroxisome, F-type H(+)-transporting ATPases-based ATP production, V-type H(+)-transporting ATPases-based transmembrane transport, protein degradation, and alternative splicing of pre-mRNAs. Roles of enzymatic and non-enzymatic antioxidants in resistance to low and high Cu were defined. The backbone paths, signaling systems, and determinants that involve resistance of filamentous fungi to high Cu were determined, discussed and outlined in a model.

  15. Erosion and Modifications of Tungsten-Coated Carbon and Copper Under High Heat Flux

    Institute of Scientific and Technical Information of China (English)

    Liu Xiang(刘翔); S.Tamura; K.Tokunaga; N.Yoshida; Zhang Fu(张斧); Xu Zeng-yu(许增裕); Ge Chang-chun(葛昌纯); N.Noda

    2003-01-01

    Tungsten-coated carbon and copper was prepared by vacuum plasma spraying (VPS)and inert gas plasma spraying (IPS), respectively. W/CFC (Tungsten /Carbon Fiber-Enhancedmaterial) coating has a diffusion barrier that consists of W and Re multi-layers pre-deposited byphysical vapor deposition on carbon fiber-enhanced materials, while W/Cu coating has a gradedtransition interface. Different grain growth processes of tungsten coatings under stable and tran-sient heat loads were observed, their experimental results indicated that the recrystallizing tem-perature of VPS-W coating was about 1400 ℃ and a recrystallized columnar layer of about 30μmthickness was formed by cyclic heat loads of 4 ms pulse duration. Erosion and modifications ofW/CFC and W/Cu coatings under high heat load, such as microstructure changes of interface,surface plastic deformations and cracks, were investigated, and the erosion mechanism erosionproducts) of these two kinds of tungsten coatings under high heat flux was also studied.

  16. High-speed blanking of copper alloy sheets: Material modeling and simulation

    Science.gov (United States)

    Husson, Ch.; Ahzi, S.; Daridon, L.

    2006-08-01

    To optimize the blanking process of thin copper sheets ( ≈ 1. mm thickness), it is necessary to study the influence of the process parameters such as the punch-die clearance and the wear of the punch and the die. For high stroke rates, the strain rate developed in the work-piece can be very high. Therefore, the material modeling must include the dynamic effects.For the modeling part, we propose an elastic-viscoplastic material model combined with a non-linear isotropic damage evolution law based on the theory of the continuum damage mechanics. Our proposed modeling is valid for a wide range of strain rates and temperatures. Finite Element simulations, using the commercial code ABAQUS/Explicit, of the blanking process are then conducted and the results are compared to the experimental investigations. The predicted cut edge of the blanked part and the punch-force displacement curves are discussed as function of the process parameters. The evolution of the shape errors (roll-over depth, fracture depth, shearing depth, and burr formation) as function of the punch-die clearance, the punch and the die wear, and the contact punch/die/blank-holder are presented. A discussion on the different stages of the blanking process as function of the processing parameters is given. The predicted results of the blanking dependence on strain-rate and temperature using our modeling are presented (for the plasticity and damage). The comparison our model results with the experimental ones shows a good agreement.

  17. Coexistence of Fermi arcs and Fermi pockets in a high-T(c) copper oxide superconductor.

    Science.gov (United States)

    Meng, Jianqiao; Liu, Guodong; Zhang, Wentao; Zhao, Lin; Liu, Haiyun; Jia, Xiaowen; Mu, Daixiang; Liu, Shanyu; Dong, Xiaoli; Zhang, Jun; Lu, Wei; Wang, Guiling; Zhou, Yong; Zhu, Yong; Wang, Xiaoyang; Xu, Zuyan; Chen, Chuangtian; Zhou, X J

    2009-11-19

    In the pseudogap state of the high-transition-temperature (high-T(c)) copper oxide superconductors, angle-resolved photoemission (ARPES) measurements have seen Fermi arcs-that is, open-ended gapless sections in the large Fermi surface-rather than a closed loop expected of an ordinary metal. This is all the more puzzling because Fermi pockets (small closed Fermi surface features) have been suggested by recent quantum oscillation measurements. The Fermi arcs cannot be understood in terms of existing theories, although there is a solution in the form of conventional Fermi surface pockets associated with competing order, but with a back side that is for detailed reasons invisible to photoemission probes. Here we report ARPES measurements of Bi(2)Sr(2-x)La(x)CuO(6+delta) (La-Bi2201) that reveal Fermi pockets. The charge carriers in the pockets are holes, and the pockets show an unusual dependence on doping: they exist in underdoped but not overdoped samples. A surprise is that these Fermi pockets appear to coexist with the Fermi arcs. This coexistence has not been expected theoretically.

  18. Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells

    Science.gov (United States)

    Zhu, Zhaozhao; Mankowski, Trent; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2016-09-01

    We report the synthesis of ultra-high aspect ratio copper nanowires (CuNW) and fabrication of CuNW-based transparent conductive electrodes (TCE) with high optical transmittance (>80%) and excellent sheet resistance (Rs zinc oxide (AZO) thin-film coatings, or platinum thin film coatings, or nickel thin-film coatings. Our hybrid transparent electrodes can replace indium tin oxide (ITO) films in dye-sensitized solar cells (DSSCs) as either anodes or cathodes. We highlight the challenges of integrating bare CuNWs into DSSCs, and demonstrate that hybridization renders the solar cell integrations feasible. The CuNW/AZO-based DSSCs have reasonably good open-circuit voltage (Voc = 720 mV) and short-circuit current-density (Jsc = 0.96 mA/cm2), which are comparable to what is obtained with an ITO-based DSSC fabricated with a similar process. Our CuNW-Ni based DSSCs exhibit a good open-circuit voltage (Voc = 782 mV) and a decent short-circuit current (Jsc = 3.96 mA/cm2), with roughly 1.5% optical-to-electrical conversion efficiency.

  19. Three-dimensional porous hollow fibre copper electrodes for efficient and high-rate electrochemical carbon dioxide reduction.

    Science.gov (United States)

    Kas, Recep; Hummadi, Khalid Khazzal; Kortlever, Ruud; de Wit, Patrick; Milbrat, Alexander; Luiten-Olieman, Mieke W J; Benes, Nieck E; Koper, Marc T M; Mul, Guido

    2016-01-01

    Aqueous-phase electrochemical reduction of carbon dioxide requires an active, earth-abundant electrocatalyst, as well as highly efficient mass transport. Here we report the design of a porous hollow fibre copper electrode with a compact three-dimensional geometry, which provides a large area, three-phase boundary for gas-liquid reactions. The performance of the copper electrode is significantly enhanced; at overpotentials between 200 and 400 mV, faradaic efficiencies for carbon dioxide reduction up to 85% are obtained. Moreover, the carbon monoxide formation rate is at least one order of magnitude larger when compared with state-of-the-art nanocrystalline copper electrodes. Copper hollow fibre electrodes can be prepared via a facile method that is compatible with existing large-scale production processes. The results of this study may inspire the development of new types of microtubular electrodes for electrochemical processes in which at least one gas-phase reactant is involved, such as in fuel cell technology.

  20. Three-dimensional porous hollow fibre copper electrodes for efficient and high-rate electrochemical carbon dioxide reduction

    Science.gov (United States)

    Kas, Recep; Hummadi, Khalid Khazzal; Kortlever, Ruud; de Wit, Patrick; Milbrat, Alexander; Luiten-Olieman, Mieke W. J.; Benes, Nieck E.; Koper, Marc T. M.; Mul, Guido

    2016-02-01

    Aqueous-phase electrochemical reduction of carbon dioxide requires an active, earth-abundant electrocatalyst, as well as highly efficient mass transport. Here we report the design of a porous hollow fibre copper electrode with a compact three-dimensional geometry, which provides a large area, three-phase boundary for gas-liquid reactions. The performance of the copper electrode is significantly enhanced; at overpotentials between 200 and 400 mV, faradaic efficiencies for carbon dioxide reduction up to 85% are obtained. Moreover, the carbon monoxide formation rate is at least one order of magnitude larger when compared with state-of-the-art nanocrystalline copper electrodes. Copper hollow fibre electrodes can be prepared via a facile method that is compatible with existing large-scale production processes. The results of this study may inspire the development of new types of microtubular electrodes for electrochemical processes in which at least one gas-phase reactant is involved, such as in fuel cell technology.

  1. Effect of inhibitors on corrosion behavior of copper-nickel in concentrated lithium bromide solution at high temperature

    Institute of Scientific and Technical Information of China (English)

    黄乃宝; 梁成浩; 佟大维

    2002-01-01

    The conventional mass-loss tests and the electrochemical techniques were used to study the inhibition action of LiOH and Na2MoO4 either individually or in different combination for copper-nickel alloy in boiling 65%LiBr solution. It indicates that the corrosion rate of copper-nickel is decreased when LiOH or Na2MoO4 is added to the solution individually. LiOH concentration has a double-effect on the corrosion behavior of copper-nickel. Low concentration is benefit to forming oxide film. High concentration results in dissolution of oxide film. The optimal concentration of LiOH is 0.15mol/L. The dissolution of copper-nickel is effectively prevented when adding 200mg/L Na2MoO4 to boiling 65%LiBr solution with 0.15mol/L LiOH. The inhibition mechanism is considered that the films of Cu, Ni, Mo oxides and deposited nonprotective in soluble CuBr on the surface of metal could prevent Br- ion from absorption, which prevent alloy dissolving.

  2. Mechanochemical reactions on copper-based compounds

    NARCIS (Netherlands)

    Castricum, H.L.; Bakker, H.; Poels, E.K.

    1999-01-01

    Mechanochemical reactions of copper and copper oxides with oxygen and carbon dioxide are discussed, as well as decomposition and reduction of copper compounds by mechanical milling under high-vacuum conditions.

  3. Involvement of nitrogen functional groups in high-affinity copper binding in tomato and wheat root apoplasts: spectroscopic and thermodynamic evidence.

    Science.gov (United States)

    Guigues, Stéphanie; Bravin, Matthieu N; Garnier, Cédric; Masion, Armand; Chevassus-Rosset, Claire; Cazevieille, Patrick; Doelsch, Emmanuel

    2016-03-01

    Carboxylic groups located in plant cell walls (CW) are generally considered to be the main copper binding sites in plant roots, despite the presence of other functional groups. The aim of this study was to investigate sites responsible for copper binding in root apoplasts, i.e. CW and outer surface of the plasma membrane (PM) continuum. Binding sites in root apoplasts were investigated by comparing isolated CW of a monocotyledon (Triticum aestivum L.) and dicotyledon (Solanum lycopersicum L.) crop with their respective whole roots. Copper speciation was examined by X-ray absorption (XAS) and (13)C-nuclear magnetic resonance spectroscopies while the affinity of ligands involved in copper binding was investigated by modeling copper sorption isotherms. Homogeneous speciation and binding of copper was found in wheat and tomato root apoplasts. Only Cu-N and Cu-O bonds were detected in wheat and tomato root apoplasts. Nitrogen/oxygen ligands were identified in slightly higher proportions (40-70%) than single oxygen ligands. Furthermore, low- and high-affinity binding sites contributed in an almost equivalent proportion to copper binding in root apoplasts. The high-affinity N functional groups embedded in root apoplasts participated in copper binding in the same magnitude than the low-affinity carboxylic groups.

  4. The Unstabilized Amalgamation of Heegaard Splittings along Disconnected Surfaces

    Institute of Scientific and Technical Information of China (English)

    Xutao GAO; Qilong GUO

    2013-01-01

    Let M be a 3-manifold,F={F1,F2,…,Fn} be a collection of essential closed surfaces in M (for any i,j ∈ {1,…,n},ifi≠ j,Fi is not parallel to Fj and Fi∩Fj =(O)) and (O)0M be a collection of components of (O)M.Suppose M-∪Fi∈F Fi × (-1,1) contains k components M1,M2,…,Mk.If each Mi has a Heegaard splitting Vi∪si Wi with d(Si) > 4(g(M1) +… + g(Mk)),then any minimal Heegaard splitting of M relative to (O)0M is obtained by doing amalgamations and self-amalgamations from minimal Heegaard splittings or (O)-stabilization of minimal Heegaard splittings of M1,M2,…,Mk.

  5. Clinicopathological and immunohistochemical study of oral amalgam pigmentation.

    Science.gov (United States)

    Vera-Sirera, Beatriz; Risueño-Mata, Presentación; Ricart-Vayá, José M; Baquero Ruíz de la Hermosa, Carmen; Vera-Sempere, Francisco

    2012-01-01

    Amalgam tattoo, the most common exogenous oral pigmentation, can sometimes be confused with melanotic lesions, being then biopsied. We present the clinicopathological characteristics of 6 biopsied cases (5 females and 1 male) of oral amalgam pigmentation. The most common location was the gingival mucosa, followed by the buccal and palatal mucosa. Morphology and distribution (stromal, perivascular, perineural, endomysial) of pigmentation was variable; there was only 1 case with fibrous capsular reaction and likewise only a single case of granulomatous foreign body reaction. Morphological variability is conditioned by the timing and amount of the pigment deposit, which is often associated with infiltration by mast cells (CD117+), as well as overexpression of metallothionein and HLA-DR at different tissue levels.

  6. Competition between the pseudogap and superconductivity in the high-T(c) copper oxides.

    Science.gov (United States)

    Kondo, Takeshi; Khasanov, Rustem; Takeuchi, Tsunehiro; Schmalian, Jörg; Kaminski, Adam

    2009-01-15

    In a classical Bardeen-Cooper-Schrieffer superconductor, pairing and coherence of electrons are established simultaneously below the critical transition temperature (T(c)), giving rise to a gap in the electronic energy spectrum. In the high-T(c) copper oxide superconductors, however, a pseudogap extends above T(c). The relationship between the pseudogap and superconductivity is one of the central issues in this field. Spectral gaps arising from pairing precursors are qualitatively similar to those caused by competing electronic states, rendering a standard approach to their analysis inconclusive. The issue can be settled, however, by studying the correlation between the weights associated with the pseudogap and superconductivity spectral features. Here we report a study of two spectral weights using angle-resolved photoemission spectroscopy. The weight of the superconducting coherent peak increases away from the node following the trend of the superconducting gap, but starts to decrease in the antinodal region. This striking non-monotonicity reveals the presence of a competing state. We demonstrate a direct correlation, for different values of momenta and doping, between the loss in the low-energy spectral weight arising from the opening of the pseudogap and a decrease in the spectral weight associated with superconductivity. We therefore conclude that the pseudogap competes with the superconductivity by depleting the spectral weight available for pairing.

  7. The Effect of Tool Position for Aluminum and Copper at High Rotational Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    Recep Çakır

    2015-12-01

    Full Text Available Friction Stir Welding (FSW is a solid state welding process used for welding similar and dissimilar materials. This welding technique allows welding of Aluminum alloys which present difficulties in fusion joining and allows different material couples to be welded continuously. In this study, 1050 aluminum alloy and commercially pure copper to increase heat input were produced at high rotation rate (2440 rev/min with four different pin position (0-1-1.5-2 mm and three different weld speeds (20-30-50 mm/min by friction stir welding. The influence of welding parameters on microstructure and mechanical properties of the joints was investigated. Tensile and bending tests and microhardness measurements were used to determine of mechanical properties. Nugget zone microstructures were investigated by optical microscope and scanning electron microscope (SEM and were analyzed in energy-dispersive X-ray spectroscopy (EDX. Depending on the XRD analysis results intermetallic phase was observed to form in the interfacial region. In the tensile test results, 83.55% weld performance was obtained in the friction stir welding merge of Al-Cu.

  8. Highly efficient copper-zinc-tin-selenide (CZTSe) solar cells by electrodeposition.

    Science.gov (United States)

    Jeon, Jong-Ok; Lee, Kee Doo; Seul Oh, Lee; Seo, Se-Won; Lee, Doh-Kwon; Kim, Honggon; Jeong, Jeung-hyun; Ko, Min Jae; Kim, BongSoo; Son, Hae Jung; Kim, Jin Young

    2014-04-01

    Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties.

  9. Function and Regulation of the Plant COPT Family of High-Affinity Copper Transport Proteins

    Directory of Open Access Journals (Sweden)

    Sergi Puig

    2014-01-01

    Full Text Available Copper (Cu is an essential micronutrient for all eukaryotes because it participates as a redox active cofactor in multiple biological processes, including mitochondrial respiration, photosynthesis, oxidative stress protection, and iron (Fe transport. In eukaryotic cells, Cu transport toward the cytoplasm is mediated by the conserved CTR/COPT family of high-affinity Cu transport proteins. This outlook paper reviews the contribution of our research group to the characterization of the function played by the Arabidopsis thaliana COPT1–6 family of proteins in plant Cu homeostasis. Our studies indicate that the different tissue specificity, Cu-regulated expression, and subcellular localization dictate COPT-specialized contribution to plant Cu transport and distribution. By characterizing lack-of-function Arabidopsis mutant lines, we conclude that COPT1 mediates root Cu acquisition, COPT6 facilitates shoot Cu distribution, and COPT5 mobilizes Cu from storage organelles. Furthermore, our work with copt2 mutant and COPT-overexpressing plants has also uncovered Cu connections with Fe homeostasis and the circadian clock, respectively. Future studies on the interaction between COPT transporters and other components of the Cu homeostasis network will improve our knowledge of plant Cu acquisition, distribution, regulation, and utilization by Cu-proteins.

  10. A photoreducible copper(II)-tren complex of practical value: generation of a highly reactive click catalyst.

    Science.gov (United States)

    Harmand, Lydie; Lambert, Romain; Scarpantonio, Luca; McClenaghan, Nathan D; Lastécouères, Dominique; Vincent, Jean-Marc

    2013-11-25

    A detailed study on the photoreduction of the copper(II) precatalyst 1 to generate a highly reactive cuprous species for the copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) click reaction is presented. For the photoactive catalyst described herein, the activation is driven by a photoinduced electron transfer (PET) process harnessing a benzophenone-like ketoprofenate chromophore as a photosensitizer, which is equally the counterion. The solvent is shown to play a major role in the Cu(II) to Cu(I) reduction process as the final electron source, and the influence of the solvent nature on the photoreduction efficiency has been studied. Particular attention was paid to the use of water as a potential solvent, aqueous media being particularly appealing for CuAAC processes. The ability to solubilize the copper-tren complexes in water through the formation of inclusion complexes with β-CDs is demonstrated. Data is also provided on the fate of the copper(I)-tren catalytic species when reacting with O2, O2 being used to switch off the catalysis. These data show that partial oxidation of the secondary benzylamine groups of the ligand to benzylimines occurs. Preliminary results show that when prolonged irradiation times are employed a Cu(I) to Cu(0) over-reduction process takes place, leading to the formation of copper nanoparticles (NPs). Finally, the main objective of this work being the development of photoactivable catalysts of practical value for the CuAAC, the catalytic, photolatent, and recycling properties of 1 in water and organic solvents are reported.

  11. Dental composites and amalgam and physical development in children.

    Science.gov (United States)

    Maserejian, N N; Hauser, R; Tavares, M; Trachtenberg, F L; Shrader, P; McKinlay, S

    2012-11-01

    Resin-based composite dental restoration materials may release bisphenol-A, an endocrine-disrupting chemical. Using secondary analysis of a randomized clinical safety trial of amalgam vs. composites, we tested the hypothesis that dental restoration materials affect children's growth. Children (N = 218 boys, N = 256 girls) aged 6 to 10 yrs at baseline with ≥ 2 decayed posterior teeth were randomized to amalgam or composites (bisphenol-A-diglycidyl-dimethacrylate composite for permanent teeth, urethane-dimethacrylate compomer for primary teeth) for treatment of posterior caries throughout follow-up. Primary outcomes for this analysis were 5-year changes in BMI-for-age z-scores, body fat percentage (BF%), and height velocity; exploratory analyses (n = 113) examined age at menarche. Results showed no significant differences between treatment assignment and changes in physical development in boys [(composites vs. amalgam) BF%, 4.9 vs. 5.7, p = 0.49; (BMI-z-score) 0.13 vs. 0.25, p = 0.36] or girls (8.8 vs. 7.7, p = 0.95; 0.36 vs. 0.21, p = 0.49). Children with more treatment on primary teeth had greater increases in BF% regardless of material type. Girls assigned to composites had lower risk of menarche during follow-up (hazard ratio = 0.57, 95% CI 0.35-0.95). Overall, there were no significant differences in physical development over 5 years in children treated with composites or amalgam. Additional studies examining these restoration materials in relation to age at menarche are warranted (clinicaltrials.gov number NCT00065988).

  12. Mercury and Amalgam Dental: Implications for Public Health

    OpenAIRE

    2016-01-01

    Environmental pollution and occupational exposures by Mercury have been associated with many health problems since the fetal life. Since amalgam is widely used in dentistry due to its ease use and lower cost, the objective of this work was to elaborate a review regarding Mercury pollution and environmental, occupational and health aspects. A review covering 2010 to 2014 period using Medline, ISI, and LILACS databases were done. Mercury is associated with reduction of physical growth and cogni...

  13. The effect of bevel angle on apical microleakage following the use of amalgam and MTA

    Directory of Open Access Journals (Sweden)

    Sharifian MR

    2006-07-01

    Full Text Available Background and Aim: Achieving appropriate seal in canal obturation is the main goal of endodontic therapy. However, in some cases, it can not be obtained by non-surgical procedures alone. Retrograde surgery is one of the most common procedures in endodontics. Apical seal improvement can be obtained by root end filling and decreasing the root end resection angle (bevel angle. The aim of this study was to investigate the role of bevel angle on apical microleakage following the use of amalgam and MTA as root end filling materials. Materials and Methods: In this experimental study, 128 extracted human teeth were instrumented and obturated by lateral condensation technique. The teeth were divided into two groups and the apical root resection was performed by high speed fissure bur (one group perpendicular to the long axis of the teeth and the other 45 to the long axis. The 3 mm root end cavity was prepared by ultrasonic device. Each group was divided into two subgroups: One filled with amalgam and the other with MTA. Teeth were incubated for 72 h, covered by two layers of nail polish (except for apical 3mm and submerged in methylene blue for 48 h. Teeth were washed under tap water and mesiodistally dissected by low speed disc. Dye penetration was evaluated by stereomicroscope. Data were analysed by two way ANOVA and Tukey tests with p<0.05 as the limit of significance. Results: The results showed that retrofill material type had a significant effect on microleakage and MTA was superior to amalgam in this respect. Bevel angle failed to show any significant effect on apical microleakage. Conclusion: Based on the results of this study, it seems that the use of MTA instead of amalgam in clinical practice can improve the success rate of endodontic surgery whereas the bevel angle can be determined based on the status of each individual case; However, increasing the bevel angle seems to increase microleakage due to exposure of more dentinal tubules.

  14. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    Science.gov (United States)

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs.

  15. Effect of rubber dam on mercury exposure during amalgam removal.

    Science.gov (United States)

    Kremers, L; Halbach, S; Willruth, H; Mehl, A; Welzl, G; Wack, F X; Hickel, R; Greim, H

    1999-06-01

    It was the aim of this investigation to treat 20 volunteers with maximally 5 amalgam fillings by the same comprehensive protocol in which all removals with (n = 8) and without (n = 12) rubber dam had been performed within a few months. Nine amalgam-related parameters indicated a close matching of both groups before removal. In the group without rubber dam, mercury (Hg) levels in plasma increased significantly above preremoval values at days 1 and 3 after removal; they decreased significantly below preremoval values at day 30 in the rubber-dam group and at day 100 in both groups. Excretion rates did not increase significantly in either group, but decreased significantly at day 100 in the protected group. Peak plasma-Hg was 0.6 ng/mL on average at day one and decreased with halftimes of 3 and 43 d in subjects protected by rubber dam. The results indicated that concentrations of total mercury in plasma responded rapidly to changes in the amalgam status and reflected the actual absorption most reliably. Notably, plasma-Hg levels were sensitive enough to detect a transient attenuation of the additional exposure by using rubber dam during the removal of only a few fillings. However, being small in magnitude and lasting 100 d at best, the rubber-dam effect had minor toxicological relevance.

  16. Mineral Liberation of Magnetite-Precipitated Copper Slag Obtained via Molten Oxidation by Using High-Voltage Electrical Pulses

    Science.gov (United States)

    Fan, Yong; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2016-10-01

    Our proposed method, i.e., a controlled molten oxidation process under 1 vol pct oxygen, leads to selective precipitation of magnetite in a copper smelter slag for downstream iron separation. In the present study, the preroasted magnetite precipitated copper slag was treated via magnetite liberation, which was realized by using high-voltage electrical pulses. The mineral distribution was determined by using a laser microscope and its image analysis; and it revealed that the 100- µm under-sieve product contains approximately 70 pct of liberated mineral particles. The study affirms the positive outcome of using this new technology for comminution to obtain micrometer-scale particles that yield monominerals via selective liberation. Using magnetic separation, iron was capable of finally separating into high- and low-iron-bearing concentrate and tailing that can be used in specific applications.

  17. A high efficacy antimicrobial acrylate based hydrogels with incorporated copper for wound healing application

    Energy Technology Data Exchange (ETDEWEB)

    Vuković, Jovana S.; Babić, Marija M.; Antić, Katarina M.; Miljković, Miona G.; Perić-Grujić, Aleksandra A.; Filipović, Jovanka M.; Tomić, Simonida Lj., E-mail: simonida@tmf.bg.ac.rs

    2015-08-15

    In this study, three series of hydrogels based on 2-hydroxyethyl acrylate and itaconic acid, unloaded, with incorporated copper(II) ions and reduced copper, were successfully prepared, characterized and evaluated as novel wound healing materials. Fourier transform infrared spectroscopy (FTIR) confirmed the expected structure of obtained hydrogels. Scanning electron microscopy (SEM) revealed porous morphology of unloaded hydrogels, and the morphological modifications in case of loaded hydrogels. Thermal characteristics were examined by differential scanning calorimetry (DSC) and the glass transition temperatures were observed in range of 12–50 °C. Swelling study was conducted in wide range of pHs at 37 °C, confirming pH sensitive behaviour for all three series of hydrogels. The in vitro copper release was investigated and the experimental data were analysed using several models in order to elucidate the transport mechanism. The antimicrobial assay revealed excellent antimicrobial activity, over 99% against Escherichia coli, Staphylococcus aureus and Candida albicans, as well as good correlation with the copper release experiments. In accordance with potential application, water vapour transmission rate, oxygen penetration, dispersion characteristics, fluid retention were observed and the suitability of the hydrogels for wound healing application was discussed. - Graphical abstract: Display Omitted - Highlights: • Design and evaluation of novel pH responsive hydrogel series. • Structural, morphological, thermal characterization and controlled copper release. • Antibacterial activity against Escherichia coli and Staphylococcus aureus over 99%. • Antifungal activity against Candida albicans over 99%. • In vitro evaluation studies revealed great potential for wound healing application.

  18. Bacterial cytosolic proteins with a high capacity for Cu(I) that protect against copper toxicity

    Science.gov (United States)

    Vita, Nicolas; Landolfi, Gianpiero; Baslé, Arnaud; Platsaki, Semeli; Lee, Jaeick; Waldron, Kevin J.; Dennison, Christopher

    2016-12-01

    Bacteria are thought to avoid using the essential metal ion copper in their cytosol due to its toxicity. Herein we characterize Csp3, the cytosolic member of a new family of bacterial copper storage proteins from Methylosinus trichosporium OB3b and Bacillus subtilis. These tetrameric proteins possess a large number of Cys residues that point into the cores of their four-helix bundle monomers. The Csp3 tetramers can bind a maximum of approximately 80 Cu(I) ions, mainly via thiolate groups, with average affinities in the (1–2) × 1017 M‑1 range. Cu(I) removal from these Csp3s by higher affinity potential physiological partners and small-molecule ligands is very slow, which is unexpected for a metal-storage protein. In vivo data demonstrate that Csp3s prevent toxicity caused by the presence of excess copper. Furthermore, bacteria expressing Csp3 accumulate copper and are able to safely maintain large quantities of this metal ion in their cytosol. This suggests a requirement for storing copper in this compartment of Csp3-producing bacteria.

  19. Research on copper removal from high copper content gold-loaded carbon and its application%高铜载金炭脱铜技术研究及应用

    Institute of Scientific and Technical Information of China (English)

    陈淑萍; 王春; 刘亚建; 赖桂华; 衷水平; 伍赠玲; 王世辉; 简伟峰

    2015-01-01

    To deal with the adverse effect high copper content gold-loaded carbon imposes on gold production in the ore-dressing plant of Zijinshan Gold Copper Mine ,a process of copper removal by cyanidation and copper reduction in the terminal stage by heap leaching is carried out to perform the experimental research on copper removal and pro -duction practice .The results show that bench scale copper removal tests by cyanidation can reach a copper removal rate of more than 91 %;the practice of copper removal by cyanidation and copper reduction in the terminal stage by heap leaching is able to cut production cost once the copper removal rate reaches 50%which is qualified for gold de-sorption .The copper grade in high copper content gold-loaded carbon decreases from more than 20 g/kg to less than 10 g/kg.The gold desorption rate of treated gold-loaded carbon under high temperature and pressure reaches more than 97 .5%and the gold grade in the carbon after gold deprivation decreases to lower than 0 .1 g/kg;the technique of copper reduction in the terminal stage by heap leaching solves the problem of copper deprived solution treatment . The process has the advantages of low cost ,less investment ,easy operation and vast sum of profits .%为解决紫金山金铜矿选矿厂产生的高铜载金炭对提金生产造成的不利影响,采用氰化脱铜-堆浸末期降铜工艺进行了除铜试验研究及生产实践。其结果表明:小型氰化脱铜试验铜脱除率可达9 l %以上;氰化脱铜-堆浸末期降铜工业生产实践中,为降低生产成本,脱铜率达50%以上即可,此时已满足解吸金的指标要求,其高铜载金炭铜品位由20 g/kg以上降到10 g/kg以下,脱铜载金炭高温高压解吸金的解吸率达到97.5%以上,脱金炭金品位基本降至0.1 g/kg以下;其堆浸末期降铜技术的应用,较好地解决了脱铜液难处理的问题。该工艺具有成本低、投资少、操作简单、效益显著等优点。

  20. Patients' experiences of changes in health complaints before, during, and after removal of dental amalgam.

    Science.gov (United States)

    Sjursen, Therese T; Binder, Per-Einar; Lygre, Gunvor B; Helland, Vigdis; Dalen, Knut; Björkman, Lars

    2015-01-01

    In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients' assigning meaning to illness experiences.

  1. Patients’ experiences of changes in health complaints before, during, and after removal of dental amalgam

    Directory of Open Access Journals (Sweden)

    Therese T. Sjursen

    2015-06-01

    Full Text Available In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients’ assigning meaning to illness experiences.

  2. Oral lichenoid contact lesions to mercury and dental amalgam--a review.

    Science.gov (United States)

    McParland, Helen; Warnakulasuriya, Saman

    2012-01-01

    Human oral mucosa is subjected to many noxious stimuli. One of these substances, in those who have restorations, is dental amalgam which contains mercury. This paper focuses on the local toxic effects of amalgam and mercury from dental restorations. Components of amalgam may, in rare instances, cause local side effects or allergic reactions referred to as oral lichenoid lesions (OLLs). OLLs to amalgams are recognised as hypersensitivity reactions to low-level mercury exposure. The use of patch testing to identify those susceptible from OLL is explored, and recommendations for removing amalgam fillings, when indicated are outlined. We conclude that evidence does not show that exposure to mercury from amalgam restorations poses a serious health risk in humans, except for an exceedingly small number of hypersensitivity reactions that are discussed.

  3. An analysis of copper transport in the insulation of high voltage transformers

    CERN Document Server

    Whitfield, T B

    2001-01-01

    Measurements of surface concentrations by XPS correlate well with measurements made with atomic absorption spectroscopy on solutions of extracts of the contaminated paper. The laboratory measurements have allowed determination of the diffusion coefficients and activation energy for the transport process and thus give a basis for interpretation of the diffusion profiles found in the transformer in terms of time and temperature of operation. The diffusion process is temperature dependant. The results have been used to produce long term prediction curves. Examination of the paper insulation and copper stress braiding during stripdown of a number of Current Transformers (FMK type 400kV) has revealed the presence of dark deposits. Copper foils are often interspersed within layers of paper insulation and mineral oil found in transformer windings. The dark deposits were often found in association with these foils, affecting several layers of paper in addition to the layer in contact with the copper foil. This thesis...

  4. Thermally Induced Ultra High Cycle Fatigue of Copper Alloys of the High Gradient Accelerating Structures

    CERN Document Server

    Heikkinen, Samuli; Wuensch, Walter

    2010-01-01

    In order to keep the overall length of the compact linear collider (CLIC), currently being studied at the European Organization for Nuclear Research (CERN), within reasonable limits, i.e. less than 50 km, an accelerating gradient above 100 MV/m is required. This imposes considerable demands on the materials of the accelerating structures. The internal surfaces of these core components of a linear accelerator are exposed to pulsed radio frequency (RF) currents resulting in cyclic thermal stresses expected to cause surface damage by fatigue. The designed lifetime of CLIC is 20 years, which results in a number of thermal stress cycles of the order of 2.33•1010. Since no fatigue data existed in the literature for CLIC parameter space, a set of three complementary experiments were initiated: ultra high cycle mechanical fatigue by ultrasound, low cycle fatigue by pulsed laser irradiation and low cycle thermal fatigue by high power microwaves, each test representing a subset of the original problem. High conductiv...

  5. Bond strength of resin composite to differently conditioned amalgam.

    Science.gov (United States)

    Ozcan, M; Vallittu, P K; Huysmans, M-C; Kalk, W; Vahlberg, T

    2006-01-01

    Bulk fracture of teeth, where a part of the amalgam restoration and/or the cusp is fractured, is a common clinical problem. The aim of this study was to evaluate the effect of different surface conditioning methods on the shear bond strength of a hybrid resin composite to fresh amalgam. Amalgams (N=84) were condensed into acrylic and randomly assigned to one of the following treatments (N=6): (1) Alloy primer + opaquer, (2) Air-particle abrasion (50 micro m Al(2)O(3)) + alloy primer + opaquer, (3) Silica coating (30 micro m SiO(x)) + silanization + opaquer, (4) Opaquer + pre-impregnated continuous bidirectional E-glass fibre sheets, (5) Silica coating + silanization + fibre sheets, (6) Silica coating + silanization + opaquer + fibre sheet application. Non-conditioned amalgam surfaces were considered as control group (7). The mean surface roughness depth (R(Z)) was measured from the control group and air-abraded amalgam surfaces. The resin composite was bonded to the conditioned amalgam specimens using polyethylene molds. All specimens were tested under dry and thermocycled (6.000, 5-55 degrees C, 30 s) conditions. The shear bond strength of resin composite to amalgam substrates was measured in a universal testing machine (1 mm/min). Surface roughness values for the non-conditioned control group (R(Z) approximately 0.14 micro m) and for air-particle abraded surfaces with either Al(2)O(3) or SiO(x) (R(Z) approximately 0.19 micro m and R(Z) approximately 0.16 micro m, respectively) did not show significant differences (p=0.23) (One-way ANOVA). In dry conditions, silica coating and silanization followed by fibre sheet application exhibited significantly higher results (14.8+/-5.6 MPa) than those of the groups conditioned with alloy primer (2.2+/-0.7 MPa) (p<0.001), air-particle abrasion+alloy primer (4.4+/-2.0 MPa, p<0.001), silica coating+silanization alone (6.2+/-0.8 MPa, p=0.009) or non-conditioned group (1.4+/-0.6, p<0.001). Silica coating and silanization followed

  6. Copper(I)-catalyzed azide-alkyne cycloadditions in microflow: catalyst activity, high-T operation, and an integrated continuous copper scavenging unit.

    Science.gov (United States)

    Varas, Alvaro Carlos; Noël, Timothy; Wang, Qi; Hessel, Volker

    2012-09-01

    AVOIDING THE COPPERS: A continuous-flow synthesis for the Cu(I) -catalyzed azide-alkyne cycloaddition reaction using [Cu(phenanthroline)(PPh₃)₂]NO₃ as a homogeneous catalyst is developed (up to 92 % isolated yield). Elevated temperatures allow achieving full conversions and using lower catalyst loadings. Residual copper in the triazole compound is efficiently removed via an inline extraction process, employing aqueous EDTA as a copper scavenger. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Fully Copper-Exchanged High-Silica LTA Zeolites as Unrivaled Hydrothermally Stable NH3 -SCR Catalysts.

    Science.gov (United States)

    Ryu, Taekyung; Ahn, Nak Ho; Seo, Seungwan; Cho, Jung; Kim, Hyojun; Jo, Donghui; Park, Gi Tae; Kim, Pyung Soon; Kim, Chang Hwan; Bruce, Elliott L; Wright, Paul A; Nam, In-Sik; Hong, Suk Bong

    2017-03-13

    Diesel engine technology is still the most effective solution to meet tighter CO2 regulations in the mobility and transport sector. In implementation of fuel-efficient diesel engines, the poor thermal durability of lean nitrogen oxides (NOx ) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high-silica LTA zeolites are demonstrated to exhibit excellent activity maintenance for NOx reduction with NH3 under vehicle simulated conditions even after hydrothermal aging at 900 °C, a critical temperature that the current commercial Cu-SSZ-13 catalyst cannot overcome owing to thermal deactivation. Detailed structural characterizations confirm the presence of Cu(2+) ions only at the center of single 6-rings that act not only as a catalytically active center, but also as a dealumination suppressor. The overall results render the copper-exchanged LTA zeolite attractive as a viable substitute for Cu-SSZ-13.

  8. Characterization of Copper Coatings Deposited by High-Velocity Oxy-Fuel Spray for Thermal and Electrical Conductivity Applications

    Science.gov (United States)

    Salimijazi, H. R.; Aghaee, M.; Salehi, M.; Garcia, E.

    2017-08-01

    Copper coatings were deposited on steel substrates by high-velocity oxy-fuel spraying. The microstructure of the feedstock copper powders and free-standing coatings were evaluated by optical and scanning electron microscopy. The x-ray diffraction pattern was utilized to determine phase compositions of powders and coatings. Oxygen content was determined by a LECO-T300 oxygen determiner. The thermal conductivity of the coatings was measured in two directions, through-thickness and in-plane by laser flash apparatus. The electrical resistivity of the coatings was measured by the four-point probe method. Oxygen content of the coatings was two times higher than that of the initial powders (0.35-0.37%). The thermal and electrical conductivities of the coatings were different depending on the direction of the measurement. The thermal and electrical conductivity of the coatings improved after annealing for 6 h at a temperature of 600°C.

  9. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin

    OpenAIRE

    Mahdi S; Bahman S; Arghavan A; Fatemeh M

    2008-01-01

    Amalgam′s non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior te...

  10. Contact hypersensitivity to mercury in amalgam restorations may mimic oral lichen planus.

    Science.gov (United States)

    Camisa, C; Taylor, J S; Bernat, J R; Helm, T N

    1999-03-01

    Oral lichenoid lesions caused by hypersensitivity to mercury in amalgam fillings may mimic oral lichen planus on clinical and histologic examination. A positive patch test reaction to more than one mercurial allergen increases confidence in the diagnosis and justifies the removal and replacement of all amalgam fillings with those made of other materials. A complete remission may be expected about 3 months after the last amalgam filling is removed.

  11. 'n Ondersoek na die amalgamering van skole in die RSA / André Johann Nel

    OpenAIRE

    Nel, André Johann

    1999-01-01

    Rationalisation, because of a lack of governmental funds, has become part of the education system of the RSA. In schools it implies that teaching posts are being reduced and that more emphasis is placed on the optimum use of physical facilities. For many smaller and rural schools, amalgamation became a possible solution to the problem. The amalgamation of schools however, implies a drastic change in the status quo. The main aim of the study is to investigate amalgamation as ...

  12. Control of Alzheimer's amyloid beta toxicity by the high molecular weight immunophilin FKBP52 and copper homeostasis in Drosophila.

    Directory of Open Access Journals (Sweden)

    Reiko Sanokawa-Akakura

    Full Text Available FK506 binding proteins (FKBPs, also called immunophilins, are prolyl-isomerases (PPIases that participate in a wide variety of cellular functions including hormone signaling and protein folding. Recent studies indicate that proteins that contain PPIase activity can also alter the processing of Alzheimer's Amyloid Precursor Protein (APP. Originally identified in hematopoietic cells, FKBP52 is much more abundantly expressed in neurons, including the hippocampus, frontal cortex, and basal ganglia. Given the fact that the high molecular weight immunophilin FKBP52 is highly expressed in CNS regions susceptible to Alzheimer's, we investigated its role in Abeta toxicity. Towards this goal, we generated Abeta transgenic Drosophila that harbor gain of function or loss of function mutations of FKBP52. FKBP52 overexpression reduced the toxicity of Abeta and increased lifespan in Abeta flies, whereas loss of function of FKBP52 exacerbated these Abeta phenotypes. Interestingly, the Abeta pathology was enhanced by mutations in the copper transporters Atox1, which interacts with FKBP52, and Ctr1A and was suppressed in FKBP52 mutant flies raised on a copper chelator diet. Using mammalian cultures, we show that FKBP52 (-/- cells have increased intracellular copper and higher levels of Abeta. This effect is reversed by reconstitution of FKBP52. Finally, we also found that FKBP52 formed stable complexes with APP through its FK506 interacting domain. Taken together, these studies identify a novel role for FKBP52 in modulating toxicity of Abeta peptides.

  13. Biogenic nanoparticles: copper, copper oxides, copper sulphides, complex copper nanostructures and their applications.

    Science.gov (United States)

    Rubilar, Olga; Rai, Mahendra; Tortella, Gonzalo; Diez, Maria Cristina; Seabra, Amedea B; Durán, Nelson

    2013-09-01

    Copper nanoparticles have been the focus of intensive study due to their potential applications in diverse fields including biomedicine, electronics, and optics. Copper-based nanostructured materials have been used in conductive films, lubrification, nanofluids, catalysis, and also as potent antimicrobial agent. The biogenic synthesis of metallic nanostructured nanoparticles is considered to be a green and eco-friendly technology since neither harmful chemicals nor high temperatures are involved in the process. The present review discusses the synthesis of copper nanostructured nanoparticles by bacteria, fungi, and plant extracts, showing that biogenic synthesis is an economically feasible, simple and non-polluting process. Applications for biogenic copper nanoparticles are also discussed.

  14. Mercury concentration in maternal serum, cord blood, and placenta in patients with amalgam dental fillings: effects on fetal biometric measurements.

    Science.gov (United States)

    Bedir Findik, Rahime; Celik, Huseyin Tugrul; Ersoy, Ali Ozgur; Tasci, Yasemin; Moraloglu, Ozlem; Karakaya, Jale

    2016-11-01

    We aimed to determine the extent to which mercury is transmitted from the mother to fetus via the umbilical cord in patients with amalgam dental fillings, and its effect on fetal biometric measurements. Twenty-eight patients as the study group with amalgam fillings, and 32 of them as the control group were included in this prospective case-control study. The mercury levels were measured in the maternal and cord venous sera, and the placental samples. Two groups were compared in terms of these and the fetal/neonatal biometric measurements. In the study group, the maternal and umbilical cord mercury levels were found to be significantly higher than those from the control group (p = 0.006 and p = 0.010, respectively). These high levels did not affect the fetal biometric measurements. The presence of high serum mercury levels in pregnant women with amalgam fillings is important, and warrants further long-term studies in order to investigate the fetal neurological effects as well.

  15. Oxidation of polycyclic aromatic hydrocarbons using Bacillus subtilis CotA with high laccase activity and copper independence.

    Science.gov (United States)

    Zeng, Jun; Zhu, Qinghe; Wu, Yucheng; Lin, Xiangui

    2016-04-01

    Bacterial laccase CueO from Escherichia coli can oxidize polycyclic aromatic hydrocarbons (PAHs); however, its application in the remediation of PAH-contaminated soil mainly suffers from a low oxidation rate and copper dependence. It was reported that a laccase with a higher redox potential tended to have a higher oxidation rate; thus, the present study investigated the oxidation of PAHs using another bacterial laccase CotA from Bacillus subtilis with a higher redox potential (525 mV) than CueO (440 mV). Recombinant CotA was overexpressed in E. coli and partially purified, exhibiting a higher laccase-specific activity than CueO over a broad pH and temperature range. CotA exhibited moderate thermostability at high temperatures. CotA oxidized PAHs in the absence of exogenous copper. Thereby, secondary heavy metal pollution can be avoided, another advantage of CotA over CueO. Moreover, this study also evaluated some unexplained phenomena in our previous study. It was observed that the oxidation of PAHs with bacterial laccases can be promoted by copper. The partially purified bacterial laccase oxidized only two of the 15 tested PAHs, i.e., anthracene and benzo[a]pyrene, indicating the presence of natural redox mediators in crude cell extracts. Overall, the recombinant CotA oxidizes PAHs with high laccase activity and copper independence, indicating that CotA is a better candidate for the remediation of PAHs than CueO. Besides, the findings here provide a better understanding of the oxidation of PAHs using bacterial laccases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Microstructural Features and Properties of High-hardness and Heat-resistant Dispersion Strengthened Copper by Reaction Milling

    Institute of Scientific and Technical Information of China (English)

    YAN Peng; LIN Chenguang; CUI Shun; LU Yanjie; ZHOU Zenglin; LI Zengde

    2011-01-01

    The oxide dispersion strengthened copper alloys are attractive due to their excellent combination of thermal and electrical conductivities,high-temperature strength and microstructure stability.To date,the state-of-art to fabrication of them was the intemal oxidation (IO) process.In this paper,alumina dispersion strengthened copper (ADSC) powders of nominal composition of Cu-2.5 vo1%Al2O3 were produced by reaction milling (RM) process which was an in-situ gas-solid reaction process.The bulk ADSC alloys for electrical and mechanical properties investigation were obtained by sintering and thereafter hot extrusion.After the hot consolidation processes,the fully densified powder compacts can be obtained.The single y-Al2O3 phase and profile broaden effects are evident in accordance with the results of X-ray diffraction (XRD); the HRB hardness of the ADSC can be as high as 95; the outcomes should be attributed to the pinning effect ofnano γ-Al2O3 on dislocations and grain boundaries in the copper matrix.The electrical conductivity of the ADSC alloy is 55%IACS (International Annealing Copper Standard).The room temperature hardness of the hot consolidated material was approximately maintained after annealing for l h at 900 ℃ in hydrogen atmosphere.In terms of the above merits,the RM process to fabricating ADSC alloys is a promising method to improve heat resistance,hardness,electrical conductivity and wear resistance properties etc.

  17. Early failure of Class II resin composite versus Class II amalgam restorations placed by dental students.

    Science.gov (United States)

    Overton, J D; Sullivan, Diane J

    2012-03-01

    Using the information from remake request slips in a dental school's predoctoral clinic, we examined the short-term survival of Class II resin composite restorations versus Class II dental amalgam restorations. In the student clinic, resin composite is used in approximately 58 percent of Class II restorations placed, and dental amalgam is used in the remaining 42 percent. In the period examined, Class II resin composite restorations were ten times more likely to be replaced at no cost to the patient than Class II dental amalgam restorations. A total of eighty-four resin composite restorations and six amalgam restorations were replaced due to an identified failure.

  18. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations

    Directory of Open Access Journals (Sweden)

    Fernanda Sardenberg

    2008-09-01

    Full Text Available The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11 were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group - the initial amalgam restorations were replaced by composite resin restorations; Flowable resin group - the ditching around the amalgam restorations was filled with flowable resin. Images of the sectioned teeth were made and the area of the cavities before and after the procedures was determined by image analysis software to assess structural loss. The data were submitted to ANOVA complemented by the Student Newman Keuls test (p < 0.05. The cavities in all the groups presented significantly greater areas after the procedures. However, the amalgam group showed more substantial dental loss. The other three groups presented no statistically significant difference in dental structure loss after the re-treatments. Thus, replacing ditched amalgam restorations by other similar restorations resulted in a significant dental structure loss while maintaining them or replacing them by resin restorations did not result in significant loss.

  19. A 3-year randomized clinical trial evaluating two different bonded posterior restorations: Amalgam versus resin composite.

    Science.gov (United States)

    Kemaloglu, Hande; Pamir, Tijen; Tezel, Huseyin

    2016-01-01

    To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months. Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3(rd) year, overall "Bravo" rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3(rd) year evaluation (P resin composite and bonded amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities.

  20. Simulation of a high-pressure water jet structure as an innovative tool for pulverizing copper ore in KGHM Polska Miedź S.A.

    Directory of Open Access Journals (Sweden)

    Przemysław Józef Borkowski

    2016-01-01

    Full Text Available Effective comminution of copper ore for further processing during flotation is still a challenge, both as a technological problem as well as for the high energy costs of such processing.A high-pressure water jet is one alternative method of preparing copper ore for final flotation, causing distinct enlargement of the surface of micronized particles, which could be profitable for copper production.As a consequence of such innovative processing, particles of copper ore become micronized, ensuring grain fractions directly useful for flotation at the exit of the pulverizing apparatus (the hydro-jetting mill.The paper presents some results of simulation as well as describing an analysis of the phenomena occurring inside the high-pressure water and abrasive-water jets of specific structures, elaborated in the aspect of developing hybrid jets of maximum erosive efficiency, potentially useful for effective pulverization.

  1. Highly efficient synthesis of phenols by copper-catalyzed hydroxylation of aryl iodides, bromides, and chlorides.

    Science.gov (United States)

    Yang, Kai; Li, Zheng; Wang, Zhaoyang; Yao, Zhiyi; Jiang, Sheng

    2011-08-19

    8-Hydroxyquinolin-N-oxide was found to be a very efficient ligand for the copper-catalyzed hydroxylation of aryl iodides, aryl bromides, or aryl chlorides under mild reaction conditions. This methodology provides a direct transformation of aryl halides to phenols and to alkyl aryl ethers. The inexpensive catalytic system showed great functional group tolerance and excellent selectivity. © 2011 American Chemical Society

  2. The Effect of Orthophosphate as a Copper Corrosion Inhibitor in High Alkalinity Drinking Water Systems

    Science.gov (United States)

    2007-03-01

    in the near future. 7 2.2. Human Health Concerns In the human body, copper is a component of proteins that perform a range of functions...chloroorganics and chloramines , as well as free available chlorine) following a three-minute reaction time and a DPD Total Chlorine Reagent packet

  3. The dynamic response of Copper 101 under high-rate loading

    NARCIS (Netherlands)

    Bragov, A. M.; Lomunov, A. K.; Abramov, A. V.; Konstantinov, A. Yu.; Sergeichev, I. V.; Braithwaite, C.; Proud, W. G.; Church, P. D.; Cullis, I. G.; Gould, P.

    2006-01-01

    The initial results of an investigation into the dynamic behavior of copper C101 are presented. This study involved several experimental technicques; quasi-static, compressive Split Hopkinson Pressure Bar (SHPB), a modified Taylor test and a direct impact method. From these studies dynamic and stati

  4. X-ray diffraction and high-resolution TEM observations of biopolymer nanoskin-covered metallic copper fine particles: preparative conditions and surface oxidation states.

    Science.gov (United States)

    Yonezawa, Tetsu; Uchida, Yoshiki; Tsukamoto, Hiroki

    2015-12-28

    Metallic copper fine particles used for electro conductive pastes were prepared by the chemical reduction of cupric oxide microparticles in the presence of gelatin. After reduction, the fine particles were collected by decantation with pH control and washing, followed by drying at a moderate temperature. The surface oxidation state of the obtained copper fine particles could be considerably varied by altering the pH of the particle dispersion, as shown by X-ray diffraction and high-resolution transmission electron microscopy. Our results strongly indicate that decantation under a nitrogen atmosphere can prevent the oxidation of copper fine particles but a slight oxidation was found.

  5. Nonafluorobutanesulfonyl azide as a shelf-stable highly reactive oxidant for the copper-catalyzed synthesis of 1,3-diynes from terminal alkynes.

    Science.gov (United States)

    Suárez, José Ramón; Collado-Sanz, Daniel; Cárdenas, Diego J; Chiara, Jose Luis

    2015-01-16

    Nonafluorobutanesulfonyl azide is a highly efficient reagent for the copper-catalyzed coupling of terminal alkynes to give symmetrical and unsymmetrical 1,3-diynes in good to excellent yields and with good functional group compatibility. The reaction is extremely fast (copper(I) or copper(II) salt (2–5 mol %) and an organic base (0.6 mol %). A possible mechanistic pathway is briefly discussed on the basis of model DFT theoretical calculations. The quantitative assessment of the safety of use and shelf stability of nonafluorobutanesulfonyl azide has confirmed that this reagent is a superior and safe alternative to other electrophilic azide reagents in use today.

  6. A significant dose-dependent relationship between mercury exposure from dental amalgams and kidney integrity biomarkers: a further assessment of the Casa Pia children's dental amalgam trial.

    Science.gov (United States)

    Geier, D A; Carmody, T; Kern, J K; King, P G; Geier, M R

    2013-04-01

    Dental amalgams are a commonly used dental restorative material. Amalgams are about 50% mercury (Hg), and Hg is known to significantly accumulate in the kidney. It was hypothesized that because Hg accumulates in the proximal tubules (PTs), glutathione-S-transferases (GST)-α (suggestive of kidney damage at the level of PT) would be expected to be more related to Hg exposure than GST-π (suggestive of kidney damage at the level of the distal tubules). Urinary biomarkers of kidney integrity were examined in children of 8-18 years old, with and without dental amalgam fillings, from a completed clinical trial (parent study). Our study determined whether there was a significant dose-dependent correlation between increasing Hg exposure from dental amalgams and GST-α and GST-π as biomarkers of kidney integrity. Overall, the present study, using a different and more sensitive statistical model than the parent study, revealed a statistically significant dose-dependent correlation between cumulative exposure to Hg from dental amalgams and urinary levels of GST-α, after covariate adjustment; where as, a nonsignificant relationship was observed with urinary levels of GST-π. Furthermore, it was observed that urinary GST-α levels increased by about 10% over the 8-year course of the study among individuals with an average exposure to amalgams among the study subjects from the amalgam group, in comparison with study subjects with no exposure to dental amalgams. The results of our study suggest that dental amalgams contribute to ongoing kidney damage at the level of the PTs in a dose-dependent fashion.

  7. In-situ measurements of low-level mercury vapor exposure from dental amalgam with zeeman atomic absorption spectroscopy.

    Science.gov (United States)

    Halbach, Stefan; Welzl, Gerhard

    2004-01-01

    Alongside food, emissions from amalgam fillings are an essential contribution to man's mercury burden. Previous methods for the determination of intraoral mercury vapor (Hg degrees ) release used principally some form of preconcentration of Hg on gold (film or wool), allowing relatively few measurements with unknown precision and sensitivity at selected times. Recently available computer-controlled Hg detectors operating on Zeeman atomic absorption spectroscopy (ZAAS) facilitate the direct real-time measurement of Hg degrees concentrations. It was the aim to adapt this method for a comparative investigation of emission processes from fillings in situ and from amalgam specimens in vitro. In addition to the ZAAS instrument, the apparatus consisted of a pump, magnetic valves, an electronic flow controller and a handle with a disposable mouth piece for aspiration of oral air. A programmable timer integrated the computer-controlled instrument operation and the data collection into a standard sampling protocol. A fast exponential decay of the emission was found after stimulation of amalgam specimens and of fillings in situ (halftimes 8.6 and 10.7 min). Precision was evaluated by a series of measurements on a single patient which indicated a consistently low coefficient of variation between 18% and 25%. After insertion of a few new fillings, sensitivity was high enough to detect a significant increase in emission against the background emission from the majority of old fillings. Zeeman-AAS in connection with a semi-automated sampling protocol and data storage provides precise in-situ measurements of Hg degrees emission from dental amalgam with real-time resolution. This facilitates the detailed exploration of the Hg degrees release kinetics and the applicability to large-scale studies.

  8. Copper hypersensitivity.

    Science.gov (United States)

    Fage, Simon W; Faurschou, Annesofie; Thyssen, Jacob P

    2014-10-01

    The world production of copper is steadily increasing. Although humans are widely exposed to copper-containing items on the skin and mucosa, allergic reactions to copper are only infrequently reported. To review the chemistry, biology and accessible data to clarify the implications of copper hypersensitivity, a database search of PubMed was performed with the following terms: copper, dermatitis, allergic contact dermatitis, contact hypersensitivity, contact sensitization, contact allergy, patch test, dental, IUD, epidemiology, clinical, and experimental. Human exposure to copper is relatively common. As a metal, it possesses many of the same qualities as nickel, which is a known strong sensitizer. Cumulative data on subjects with presumed related symptoms and/or suspected exposure showed that a weighted average of 3.8% had a positive patch test reaction to copper. We conclude that copper is a very weak sensitizer as compared with other metal compounds. However, in a few and selected cases, copper can result in clinically relevant allergic reactions.

  9. Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains and microbial community succession analysis

    Science.gov (United States)

    Hao, Xiao-dong; Liang, Yi-li; Yin, Hua-qun; Liu, Hong-wei; Zeng, Wei-min; Liu, Xue-duan

    2017-04-01

    Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains was carried out by mixed cultures on a small scale over a period of 210 d. Lump ores as a framework were loaded at the bottom of the ore heap. The overall copper leaching rates of tailings and lump ores were 57.10wt% and 65.52wt%, respectively. The dynamic shifts of microbial community structures about attached microorganisms were determined using the Illumina MiSeq sequencing platform based on 16S rRNA amplification strategy. The results indicated that chemolithotrophic genera Acidithiobacillus and Leptospirillum were always detected and dominated the microbial community in the initial and middle stages of the heap bioleaching process; both genera might be responsible for improving the copper extraction. However, Thermogymnomonas and Ferroplasma increased gradually in the final stage. Moreover, the effects of various physicochemical parameters and microbial community shifts on the leaching efficiency were further investigated and these associations provided some important clues for facilitating the effective application of bioleaching.

  10. Highly sensitive visual detection of copper (II) using water-soluble azide-functionalized gold nanoparticles and silver enhancement.

    Science.gov (United States)

    Zhang, Zhen; Li, Wenqing; Zhao, Qiuling; Cheng, Ming; Xu, Li; Fang, Xiaohong

    2014-09-15

    A high-sensitive method for the visual detection of copper ions in aqueous solution is developed. The method is based on copper ion-catalyzed 'click' reaction between the water-soluble azide-functionalized gold nanoparticles (AuNPs) and alkyne-modified glass slide. The PEG linker was employed as a stabilizing component along with the terminal azide group to keep the AuNPs stably dispersed in water without the assistance of any organic solvent. In the presence of copper ions, the AuNPs are 'clicked' on the slide, and the darkness of the AuNPs in the sample spot is promoted by silver enhancement process. Only a tiny amount of sample (10 μl) is needed with the detectable concentration down to 62 pM by the commonly used flatbed scanner, which is 2-3 orders of magnitude lower than those in previous reports. The selectivity relative to other potentially interfering ions and the applicability in real samples, human serum and tap water, have also been evaluated. Our method has a good potential in point-of-use applications and environment surveys. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. INTERACTION OF COPPER BASED PRESERVATIVES WITH WOOD

    Directory of Open Access Journals (Sweden)

    Ali Temiz

    2004-11-01

    Full Text Available Copper is highly toxic to fungi and the element is widely used in many preservative formulations over 50 years. The interactions of wood and copper-based preservatives impact both the performance and the environment aspects of treated wood. Copper might be present in treated wood as coppercellulose complex, copper-lignin complex, and crystalline or amorphous inorganic/organic copper compounds. In this review; it was aimed to investigate the interactions of wood and copper-based preservatives, Copper Adsorpsion factors and copper forms in treated wood

  12. The Mitochondrial Metallochaperone SCO1 Is Required to Sustain Expression of the High-Affinity Copper Transporter CTR1 and Preserve Copper Homeostasis

    Directory of Open Access Journals (Sweden)

    Christopher J. Hlynialuk

    2015-02-01

    Full Text Available Human SCO1 fulfills essential roles in cytochrome c oxidase (COX assembly and the regulation of copper (Cu homeostasis, yet it remains unclear why pathogenic mutations in this gene cause such clinically heterogeneous forms of disease. Here, we establish a Sco1 mouse model of human disease and show that ablation of Sco1 expression in the liver is lethal owing to severe COX and Cu deficiencies. We further demonstrate that the Cu deficiency is explained by a functional connection between SCO1 and CTR1, the high-affinity transporter that imports Cu into the cell. CTR1 is rapidly degraded in the absence of SCO1 protein, and we show that its levels are restored in Sco1−/− mouse embryonic fibroblasts upon inhibition of the proteasome. These data suggest that mitochondrial signaling through SCO1 provides a post-translational mechanism to regulate CTR1-dependent Cu import into the cell, and they further underpin the importance of mitochondria in cellular Cu homeostasis.

  13. Interfacial bonding enhancement of reel-to-reel selective electrodeposition of copper stabilizer on a multifilamentary second-generation high-temperature superconductor tape

    Science.gov (United States)

    Cai, Xinwei; Li, Wei; Bose, Anima; Selvamanickam, Venkat

    2016-10-01

    A reel-to-reel copper selective electrodeposition process over a multifilamentary second-generation high-temperature superconductor (2G-HTS) has been demonstrated in our previous work. If the interfacial bonding between the deposited copper layer and the underlying silver overlayer is weak, it might lead to delamination in applications including magnets, motors and generators. In this study, two approaches have been used to improve the copper-silver bonding without the degradation of superconductor performance. The first approach is acidifying the electrolyte by adding sulfuric acid, by which the kinetics of copper electrodeposition is enhanced, resulting in finer microstructure at the copper-silver interface and thus, improved interfacial bonding strength. The second approach consists of blocking the electrolyte outflow at the entrance of the reel-to-reel electroplating cell, by which the occurrence of large copper seeds on the tape caused by the heavy turbulence flow is effectively prevented. With these two improvements together deployed in the process, the peeling strength between the copper and silver layers of the 2G-HTS tape has been improved from 2 N in 90° peeling and from 3.0 N in 180° peeling, without any degradation on the superconducting performance.

  14. Intensive Plasmonic Flash Light Sintering of Copper Nanoinks Using a Band-Pass Light Filter for Highly Electrically Conductive Electrodes in Printed Electronics.

    Science.gov (United States)

    Hwang, Yeon-Taek; Chung, Wan-Ho; Jang, Yong-Rae; Kim, Hak-Sung

    2016-04-06

    In this work, an intensive plasmonic flash light sintering technique was developed by using a band-pass light filter matching the plasmonic wavelength of the copper nanoparticles. The sintering characteristics, such as resistivity and microstructure, of the copper nanoink films were studied as a function of the range of the wavelength employed in the flash white light sintering. The flash white light irradiation conditions (e.g., wavelength range, irradiation energy, pulse number, on-time, and off-time) were optimized to obtain a high conductivity of the copper nanoink films without causing damage to the polyimide substrate. The wavelength range corresponding to the plasmonic wavelength of the copper nanoparticles could efficiently sinter the copper nanoink and enhance its conductivity. Ultimately, the sintered copper nanoink films under optimal light sintering conditions showed the lowest resistivity (6.97 μΩ·cm), which was only 4.1 times higher than that of bulk copper films (1.68 μΩ·cm).

  15. Rondeau Seminars amalgamated mid-sagittal (lateral) cephalometric analysis.

    Science.gov (United States)

    Palencar, Adrian J

    2014-01-01

    The author presents a comprehensive International Association for Orthodontics--Rondeau Seminars Amalgamated Mid-sagittal (Lateral) Cephalometric Analysis. Norms on the Cephalometric Data Sheet are age and gender specific for the Caucasian population and the postings are color coded for visual attraction. If the patient is ofa different ethnic group, the Norms should be adjusted accordingly. This Cephalometric Analysis is comprised often Sections, in alphabetical order and twenty nine Factors. The author expanded Rondeau Seminars Cephalometric Analysis by only six Factors, thus fulfilling the requirement for the case presentation for the Fellow of the IAO and the Diplomate ofthe IBO.

  16. From Strong Amalgamability to Modularity of Quantifier-Free Interpolation

    CERN Document Server

    Bruttomesso, Roberto; Ranise, Silvio

    2012-01-01

    The use of interpolants in verification is gaining more and more importance. Since theories used in applications are usually obtained as (disjoint) combinations of simpler theories, it is important to modularly re-use interpolation algorithms for the component theories. We show that a sufficient and necessary condition to do this for quantifier-free interpolation is that the component theories have the 'strong (sub-)amalgamation' property. Then, we provide an equivalent syntactic characterization, identify a sufficient condition, and design a combined quantifier-free interpolation algorithm capable of handling both convex and non-convex theories, that subsumes and extends most existing work on combined interpolation.

  17. Reagents for selective extraction of nickel(II), cobalt(II) and copper(II) from highly acidic sulfate feeds containing iron

    OpenAIRE

    Roebuck, James William

    2015-01-01

    This thesis focuses on development of new regents which are suitable for recovering nickel, cobalt and copper from laterite leach solutions, specifically focusing on reagent requirements for novel base metal flowsheets developed by Anglo American. The work aims to design reagents which can extract nickel(II), cobalt(II) and copper(II) from a highly acidic aqueous sulfate solutions whilst showing selectivity over iron(II) and iron(III). Chapter 1 reviews current extractive metallur...

  18. Copper transport.

    Science.gov (United States)

    Linder, M C; Wooten, L; Cerveza, P; Cotton, S; Shulze, R; Lomeli, N

    1998-05-01

    In adult humans, the net absorption of dietary copper is approximately 1 mg/d. Dietary copper joins some 4-5 mg of endogenous copper flowing into the gastrointestinal tract through various digestive juices. Most of this copper returns to the circulation and to the tissues (including liver) that formed them. Much lower amounts of copper flow into and out of other major parts of the body (including heart, skeletal muscle, and brain). Newly absorbed copper is transported to body tissues in two phases, borne primarily by plasma protein carriers (albumin, transcuprein, and ceruloplasmin). In the first phase, copper goes from the intestine to the liver and kidney; in the second phase, copper usually goes from the liver (and perhaps also the kidney) to other organs. Ceruloplasmin plays a role in this second phase. Alternatively, liver copper can also exit via the bile, and in a form that is less easily reabsorbed. Copper is also present in and transported by other body fluids, including those bathing the brain and central nervous system and surrounding the fetus in the amniotic sac. Ceruloplasmin is present in these fluids and may also be involved in copper transport there. The concentrations of copper and ceruloplasmin in milk vary with lactational stage. Parallel changes occur in ceruloplasmin messenger RNA expression in the mammary gland (as determined in pigs). Copper in milk ceruloplasmin appears to be particularly available for absorption, at least in rats.

  19. Highly selective and sensitive determination of copper ion by two novel optical sensors

    Directory of Open Access Journals (Sweden)

    Mehrorang Ghaedi

    2017-05-01

    Full Text Available New optical sensors for the determination of copper ion by incorporation of 1,1′-(4-nitro-1,2-phenylenebis(azan-1-yl-1-ylidenebis(methan-1-yl-1-lidenedinaphthalen-2-ol(L1, 1,1′-2,2′-(1,2-phenylenebis(ethene-2,1-diyldinaphthalen-2-ol 1(L2, dibutylphthalate (DBP and sodium tetraphenylborate (Na-TPB to the plasticized polyvinyl chloride matrices were prepared. The tendency of both ionophores (L2 and L1 as chromoionophore was significantly enhanced by the addition of DBP to the membrane. The proposed sensors benefit from advantages such as high stability, reproducibility and relatively long lifetime, good selectivity for Cu2+ ion determination over a large number of alkali, alkaline earth, transition and heavy metal ions. At optimum values of membrane compositions and experimental conditions, both sensors’ response was linear over a concentration range of 7.98 × 10−6 to 1.31 × 10−4mol L−1 and 1.99 × 10−6 to 5.12 × 10−5 mol L−1 for L2 and L1, respectively. Sensor detection limit based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three times of its standard deviation was found to be 3.99 × 10−7 and 5.88 × 10−7 mol L−1 for L2 and L1, respectively. The response time of the optodes (defined as the time required reaching the 90% of the peak signal was found to be 5–8 min for L2 and 20–25 min for L1 based sensor. The proposed optical sensors were applied successfully for the determination of Cu2+ ion content in water samples.

  20. Nontoxic and abundant copper zinc tin sulfide nanocrystals for potential high-temperature thermoelectric energy harvesting.

    Science.gov (United States)

    Yang, Haoran; Jauregui, Luis A; Zhang, Genqiang; Chen, Yong P; Wu, Yue

    2012-02-01

    Improving energy/fuel efficiency by converting waste heat into electricity using thermoelectric materials is of great interest due to its simplicity and reliability. However, many thermoelectric materials are composed of either toxic or scarce elements. Here, we report the experimental realization of using nontoxic and abundant copper zinc tin sulfide (CZTS) nanocrystals for potential thermoelectric applications. The CZTS nanocrystals can be synthesized in large quantities from solution phase reaction and compressed into robust bulk pellets through spark plasma sintering and hot press while still maintaining nanoscale grain size inside. Electrical and thermal measurements have been performed from 300 to 700 K to understand the electron and phonon transports. Extra copper doping during the nanocrystal synthesis introduces a significant improvement in the performance.

  1. Photoneutron production in tungsten, praseodymium, copper and beryllium by using high energy electron linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Jallu, F. E-mail: jalluf@macadam.cea.fr; Lyoussi, A.; Payan, E.; Recroix, H.; Mariani, A.; Nurdin, G.; Buisson, A.; Allano, J

    1999-09-01

    This paper presents comparisons between photoneutron production measurements in tungsten, copper, praseodymium and beryllium, and calculated data resulting from the ELEPHANT (ELEctron, PHoton And Neutron Transport) code. Measurements were made using the DGA/ETCA linear electron accelerator located at Arcueil, France. Bremsstrahlung endpoints varying in the 15-25 MeV energy range were used. Detectors were positioned at different angles with respect to the electron beam axis. Each measured value is compared with the corresponding calculated value.

  2. Regenerable copper-based sorbents for high temperature flue gas desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Cengiz, P.; Abbasian, J.; Slimane, R.B.; Williams, B.E.; Khalili, N.R.; Ho, K.K.

    2000-07-01

    During conventional combustion process the sulfur in the coal is converted to sulfur dioxide (SO{sub 2}). This hazardous air pollutant combines with the moisture in the atmosphere and creates what is commonly known as acid rain. Thus the removal of this pollutant from flue gas prior to its discharge is very important. Government regulations have been introduced and have become progressively more stringent. In the Clean Air Act Amendments (CAAA) of 1990, for example, legislation was introduced requiring electric utilities to adopt available technology for removal of pollutant gases and particulates from coal combustion flue gases so that the increased use of coal is done in an environmentally acceptable manner. A number of processes have been developed for flue gas desulfurization (FGD). The moving bed copper oxide process has been regarded as one of the most promising emerging technologies for SO{sub 2} and NO{sub x} removal from flue gases at elevated temperatures. This process is based on the utilization of a dry, regenerable sorbent, that consists of copper oxide (CuO) supported on gamma alumina ({gamma}-Al{sub 2}O{sub 3}), in a cross flow moving-bed reactor. This study has been directed toward evaluation of the commercially available alumina-supported copper-based (ALCOA) sorbent to establish the baseline for development of new and improved sorbents for the copper oxide process. Evaluation of the baseline sorbent included determination of effective sulfur capacity and sulfur removal efficiency of the sorbent, the effects of operating parameters on the performance of the sorbent, as well as long term durability of the sorbent. Physical and chemical properties of the baseline sorbent were also determined.

  3. Copper hypersensitivity

    DEFF Research Database (Denmark)

    Fage, Simon W; Faurschou, Annesofie; Thyssen, Jacob P

    2014-01-01

    hypersensitivity, a database search of PubMed was performed with the following terms: copper, dermatitis, allergic contact dermatitis, contact hypersensitivity, contact sensitization, contact allergy, patch test, dental, IUD, epidemiology, clinical, and experimental. Human exposure to copper is relatively common...

  4. [Black or white--is amalgam 'out'? Part 1. Amalgam or composite: which of these 2 materials is the most deleterious?].

    Science.gov (United States)

    De Moor, Roeland; Delmé, Katleen

    2008-01-01

    Dental amalgam containing mercury has been condemned because of its toxicity and hence to be damaging of harmful to the general health. It must be clear that many sensational, confusing and misleading reports have been published. Today there is evidence that dental amalgam in the oral cavity does not harm anyone's health. For those who are condemning amalgam there an abundant number of alarming reports taking into consideration the biologic effects of resin composites: methacrylate allergy for dentists and dental technicians, the three-finger-syndrome due to contact with liquid resin, allergic reactions at the level of the airways and breathing problems caused by dust particles (esp. composite particles after polishing procedures) have been described. It can be concluded that dental amalgam is not more toxic than resin composite in light of both patients' and dental care providers' health. Recent investigations demonstrated higher than expected health risks with resin composites.

  5. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations.

    Science.gov (United States)

    Sardenberg, Fernanda; Bonifácio, Clarissa Calil; Braga, Mariana Minatel; Imparato, José Carlos Pettorossi; Mendes, Fausto Medeiros

    2008-01-01

    The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11) were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group - the initial amalgam restorations were replaced by composite resin restorations; Flowable resin group - the ditching around the amalgam restorations was filled with flowable resin. Images of the sectioned teeth were made and the area of the cavities before and after the procedures was determined by image analysis software to assess structural loss. The data were submitted to ANOVA complemented by the Student Newman Keuls test (p structure loss after the re-treatments. Thus, replacing ditched amalgam restorations by other similar restorations resulted in a significant dental structure loss while maintaining them or replacing them by resin restorations did not result in significant loss.

  6. On Reduced Amalgamated Free Products of C*-algebras and the MF-Property

    DEFF Research Database (Denmark)

    Seebach, Jonas A.

    We establish an isomorphism of the group von Neumann algebra of an amalgamated free product of countable Abelian discrete groups. This result is then used to give some new examples of reduced group $ C^* $-algebras which are MF. Finally, we give a characterization of the amalgamated free products...

  7. EDS and μ-XRF mapping of amalgam degradation products in ancient mirrors.

    Science.gov (United States)

    Arizio, E; Orsega, E F; Falcone, R; Vallotto, M

    2014-12-01

    An amalgam mirror is a mirror type, used from the fifteenth century until the end of the nineteenth century, where the reflective layer is constituted by a tin amalgam layer adhered to a glass sheet. In this work, two amalgam mirrors samples were studied by scanning electron microscopy with an energy dispersive spectrometer and by micro-X-ray fluorescence elemental mapping to go deeply into the understanding of the degradation mechanism of the amalgam layer of ancient mirrors. The investigation has been focused for the first time on the reflective surface of the amalgam layer adherent to the glass sheet to better understand the processes of amalgam corrosion. The two amalgam degradation compounds, romarchite and cassiterite, has been spatially differentiated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) maps. SEM images and micro-X-ray fluorescence and EDS maps showed that the amalgam degradation products grow up to form hemispherical stratified calottes. This structure is probably due to a mechanism involves cyclic phases and oxygen radial diffusion from a superficial oxidation nucleus.

  8. Tin amalgam mirrors: investigation by XRF, SEM-EDS, XRD and EPMA-WDS mapping

    Science.gov (United States)

    Arizio, E.; Orsega, E. F.; Sommariva, G.; Falcone, R.

    2013-06-01

    Ancient mirrors were constituted by a tin-mercury amalgam layer superimposed to a glass sheet. This was the only one method used until the nineteenth century, when the wet silvering process was invented. The tin amalgam is a binary alloy of tin and mercury constituted by two different phases: a mercury-rich liquid phase and a tin-rich solid phase. The amalgam alteration produces mercury loss and a general growth of the solid crystalline phase. In addition, tin dioxide and monoxide are formed with a consequent decrease of the amalgam adhesion to the glass. These degradation phenomena led to reduction or disappearance of the mirror reflective power. The aim of this study was the characterization of the amalgam layers of eight mirror samples dating during the seventeenth and nineteenth centuries. The samples were analyzed by X-ray diffraction and by a Scanning Electron Microscope with an Energy Dispersive Spectrometer (SEM-EDS), and for the first time on this type of alloy by X-ray Fluorescence and EPMA-WDS (Electron Probe Micro Analysis with Wavelength Dispersive Spectrometry) elemental mapping. The contents of tin, mercury, and some trace elements in the amalgam layers have been determined. The investigation of the superficial patterns of the amalgam by SEM, EPMA-WDS mapping, and SEM-EDS allowed a first understanding of some morphologies and processes of the degradation of the amalgam layer.

  9. An elementary study of deformation of molar teeth during amalgam restorative procedures.

    Science.gov (United States)

    Bell, J G

    1977-06-01

    A technique using an optical comparator was employed to examine the dimensional changes resulting from cavity preparation, application of the matrix and packing with amalgam in three extracted molar teeth. The changes have been reported and the nature of the change discussed. A modification in the use of the matrix and amalgam packing technique is suggested.

  10. 高强化铜电解精炼新工艺与生产实践%Electrolytic Refining Technology of High Strengthen Copper and Production Practice

    Institute of Scientific and Technical Information of China (English)

    周松林

    2013-01-01

    The copper electrolytic refining technology with high current density and plant practice were introduced. This new technology was successfully commercialized in large-scale production in Xiangguang Copper for the first time. The current density for copper electrolysis is increased to 420 A/m2, and copper electrolytic capacity is greatly improved.%介绍了高电流密度铜电解精炼新工艺技术及生产实践.该技术首次在祥光铜业大规模工业生产中成功应用,使铜电解电流密度提高到420 A/m2,大幅提高了铜电解产能.

  11. 混酸电解高杂铜的综合回收实验%Comprehensive recovery of the mixed acid electrolytic high copper scrap

    Institute of Scientific and Technical Information of China (English)

    何旺才; 唐庆丰

    2014-01-01

    This discussion in the lead oxide residue, a small blast furnaces for smelting, liquation furnace after removal of copper are copper slag, and then through the fire method for smelting cast high copper anode plate at low current density electrolysis refining process characteristics and technical conditions for recovering copper and precious metals control and achieved the expected results.%论述了自金银冶炼产生的氧化渣中,采用小型鼓风炉进行还原熔炼、熔析炉除铜后得到铜渣,再经过火法冶炼浇铸成高杂铜阳极板,在低电流密度下电解精炼回收铜和贵金属工艺的特点及技术条件的控制,并取得了预期的效果。

  12. Highly active and selective catalysis of copper diphosphine complexes for the transformation of carbon dioxide into silyl formate.

    Science.gov (United States)

    Motokura, Ken; Kashiwame, Daiki; Takahashi, Naoki; Miyaji, Akimitsu; Baba, Toshihide

    2013-07-22

    Copper diphosphine complexes have been found to be highly active and selective homogeneous catalysts for the hydrosilylation of CO2. The structure of the phosphine ligands strongly affects their catalytic activity. Turnover number (TON) reaches 70,000 after 24 hours with 1,2-bis(diisopropylphosphino)benzene as a ligand under 1 atmosphere of CO2. (1)H and (13)C NMR spectra, carried out under the reaction conditions, showed the reaction mechanism through insertion of CO2 into Cu-H to afford Cu/formate species.

  13. Direct electroplating of copper on tantalum from ionic liquids in high vacuum: origin of the tantalum oxide layer.

    Science.gov (United States)

    Schaltin, Stijn; D'Urzo, Lucia; Zhao, Qiang; Vantomme, André; Plank, Harald; Kothleitner, Gerald; Gspan, Christian; Binnemans, Koen; Fransaer, Jan

    2012-10-21

    In this paper, it is shown that high vacuum conditions are not sufficient to completely remove water and oxygen from the ionic liquid 1-ethyl-3-methylimidazolium chloride. Complete removal of water demands heating above 150 °C under reduced pressure, as proven by Nuclear Reaction Analysis (NRA). Dissolved oxygen gas can only be removed by the use of an oxygen scavenger such as hydroquinone, despite the fact that calculations show that oxygen should be removed completely by the applied vacuum conditions. After applying a strict drying procedure and scavenging of molecular oxygen, it was possible to deposit copper directly on tantalum without the presence of an intervening oxide layer.

  14. One-step synthesis of xanthones catalyzed by a highly efficient copper-based magnetically recoverable nanocatalyst.

    Science.gov (United States)

    Menéndez, Cintia A; Nador, Fabiana; Radivoy, Gabriel; Gerbino, Darío C

    2014-06-06

    A versatile and highly efficient strategy to construct a xanthone skeleton via a ligand-free intermolecular catalytic coupling of 2-substituted benzaldehydes and a wide range of phenols has been developed. For this purpose, a novel and magnetically recoverable catalyst consisting of copper nanoparticles on nanosized silica coated maghemite is presented. The reaction proceeds smoothly with easy recovery and reuse of the catalyst. The methodology is compatible with various functional groups and provides an attractive protocol for the generation of a small library of xanthones in very good yield.

  15. Development of high-efficiency solar cells on copper indium selenide single crystals (cadmium sulfide, zinc oxide)

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Lap Sum

    1996-12-31

    Photovoltaic cells with a ZnO/CdS/CuInSe{sub 2} structure were fabricated on bulk CuInSe{sub 2} substrates. Conversion efficiencies of more than or near 10 per cent were obtained on cells with an active area and without the use of antireflection coating. Copper indium selenide single crystals can be used as absorbers in thin film solar cells. In this study, the single crystals were grown by a horizontal Bridgman method. An annealing of the CuInSe{sub 2} substrate before the CdS deposition was found to be essential in obtaining high photovoltaic performance.

  16. Amalgam and composite posterior restorations: curriculum versus practice in operative dentistry at a US dental school.

    Science.gov (United States)

    Ottenga, Marc E; Mjör, Ivar

    2007-01-01

    This study recorded the number of preclinical lecture and simulation laboratory sessions spent teaching the preparation and placement of amalgam and resin composite posterior restorations. These data were compared to the use of both materials in the operative clinic as placed by third- and fourth-year students. The number of posterior restorations inserted by the students, expressed as a function of the number of restoration surfaces, was also evaluated. The results show that the teaching of posterior restorations pre-clinically has consistently favored amalgam 2.5 to 1 during the last three years. However, clinically, resin composite is being used for posterior restorations 2.3 times more often than amalgam. The only instance that favored amalgam over composite during the last year was in the placement of four surface posterior restorations. This shift in emphasis from amalgam to composite needs to be addressed within dental educational institutions so that newly graduated dentists are prepared to place composite restorations properly.

  17. ASSESSMENT OF MERCURY RELEASE FROM DENTAL AMALGAM: AN IN VITRO STUDY

    Directory of Open Access Journals (Sweden)

    Shetty Aditya

    2013-08-01

    Full Text Available Exposure to mercury from dental amalgam restoration, with possible negative health effects, has generally been considered to occur via either erosion or evaporation directly from the surface of fillings, followed by ingestion. This study aims to assess the mercury release from dental amalgam and provide a basis for comparison between mercury release in oral cavities with single and multiple amalgam restorations at different time intervals. This study was conducted in A.B. Shetty Memorial Institute of Dental Sciences, Mangalore, Karnataka, and included three groups I , II and III containing one, four and eight teeth respectively. The level of mercury vapors released from dental amalgam restorations was calculated from artificial saliva and measured using an atomic absorption spectrophotometer. The obtained results concluded that the continuous release of Hg vapor from dental amalgam tooth restorations decreases as the restoration ages, after 30 days there was no significant difference between the amount of mercury released from multiple and single tooth restorations.

  18. A variety of amalgamated allusion in Saeb’s sonnet

    Directory of Open Access Journals (Sweden)

    Siavash Haghjoo

    2014-12-01

    Full Text Available Abstract Poetic figures of speech are among the factors which their prominence in a poet’s poetry makes up his/her specific style. One of the figures of speech and poetic techniques is allusive figures of speech or amalgamated allusions. As the name entails, these are types of figures in which allusion is located at the center and amalgamates with other figures. Such amalgamation brings about a novel complicated figure of speech.  One special type of allusive figures of speech is an allusion which is occasionally amalgamated with metaphor and ambiguity, and at times in addition to metaphor and ambiguity with simile. The origin of this figure, which is recently referred to as “metaphoric ambiguous allusion, is traced back to Hakim baz in Persian literature. Although, poetry of Hafez is replete with metaphoric ambiguous allusion, it is considerably ubiquitous in Indian style in a way that its ignorance especially in Saeb’s poetry implies the denial of one of its foremost stylistic qualities. The mixed nature of this figure and the presence of several robust figures besides each other which are the basis of poetic fantasy and a fantastic presentation is created by combination of these figures. These figures invite readers into a mode of reflection and thinking and opens corridors of fantasy towards him replete with unsurpassable satisfaction. Such amalgamated figure is formed when a poet grants an allusion to a phenomenon which in reality the phenomenon owns such quality but in a different conceptualization. Supposedly, the given figure was Saeb’s major artifact which helped him to fulfill his distinct poetic quality i.e. unsurpassed power of creating vivacious contents. The present article intended to conduct a supplementary reanalysis of “metaphoric ambiguous allusion and its different varieties and examined it in Saeb’s Poetry. Metaphoric ambiguous allusion refers to a metaphor which alludes to something. The characteristics of the

  19. Unravelling the Chemical Nature of Copper Cuprizone

    OpenAIRE

    Messori, L.; Casini, A.; C.Gabbiani; Sorace, L.; Muniz-Miranda, M.; Zatta, P

    2007-01-01

    During the last 50 years, formation of the highly chromogenic copper cuprizone complex has been exploited for spectrophotometric determinations of copper although the precise chemical nature of the resulting species has never been ascertained; we eventually show here, in contrast to current opinion, that copper cuprizone is a copper(III) complex.

  20. Mercury exposure and risks from dental amalgam in the US population, post-2000.

    Science.gov (United States)

    Richardson, G M; Wilson, R; Allard, D; Purtill, C; Douma, S; Gravière, J

    2011-09-15

    Dental amalgam is 50% metallic mercury (Hg) by weight and Hg vapour continuously evolves from in-place dental amalgam, causing increased Hg content with increasing amalgam load in urine, faeces, exhaled breath, saliva, blood, and various organs and tissues including the kidney, pituitary gland, liver, and brain. The Hg content also increases with maternal amalgam load in amniotic fluid, placenta, cord blood, meconium, various foetal tissues including liver, kidney and brain, in colostrum and breast milk. Based on 2001 to 2004 population statistics, 181.1 million Americans carry a grand total of 1.46 billion restored teeth. Children as young as 26 months were recorded as having restored teeth. Past dental practice and recently available data indicate that the majority of these restorations are composed of dental amalgam. Employing recent US population-based statistics on body weight and the frequency of dentally restored tooth surfaces, and recent research on the incremental increase in urinary Hg concentration per amalgam-filled tooth surface, estimates of Hg exposure from amalgam fillings were determined for 5 age groups of the US population. Three specific exposure scenarios were considered, each scenario incrementally reducing the number of tooth surfaces assumed to be restored with amalgam. Based on the least conservative of the scenarios evaluated, it was estimated that some 67.2 million Americans would exceed the Hg dose associated with the reference exposure level (REL) of 0.3 μg/m(3) established by the US Environmental Protection Agency; and 122.3 million Americans would exceed the dose associated with the REL of 0.03 μg/m(3) established by the California Environmental Protection Agency. Exposure estimates are consistent with previous estimates presented by Health Canada in 1995, and amount to 0.2 to 0.4 μg/day per amalgam-filled tooth surface, or 0.5 to 1 μg/day/amalgam-filled tooth, depending on age and other factors.

  1. A Lower Bound of the Genus of a Self-amalgamated 3-manifolds

    Institute of Scientific and Technical Information of China (English)

    LI XU; LEI FENG-CHUN

    2011-01-01

    Let M be a compact connected oriented 3-manifold with boundary,Q1, Q2 (C)(э)M be two disjoint homeomorphic subsurfaces of (э)M, and h: Q1 → Q2 be an orientation-reversing homeomorphism. Denote by Mh or MQ1=Q2 the 3-manifold obtained from M by gluing Q1 and Q2 together via h. Mh is called a self-amalgamation of M along Q1 and Q2. Suppose Q1 and Q2 lie on the same component F′ of (э)M′, and F′ - Q1 ∪ Q2 is connected. We give a lower bound to the Heegaard genus of M when M′ has a Heegaard splitting with sufficiently high distance.

  2. Residual stress in copper containing a high concentration of krypton precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Haerting, M.; Yaman, M.; Bucher, R.; Britton, D.T. [Department of Physics, University of Cape Town, Rondebosch 7701 (South Africa)

    2002-08-01

    A study of the residual stress and bubble pressure in bulk samples of copper, containing 3 at.-% krypton, using X-ray diffraction techniques is presented here. The authors have confirmed that the Kr forms solid precipitates with an fcc structure, which is consistent with an estimated pressure of 2.4 GPa. Stress measurements in the surrounding Cu matrix indicate a zero normal stress, confirming that the matrix experiences only a shear strain. The magnitude of the shear stress is estimated from the bubble pressure to be below the yield stress of the matrix, thus explaining the long term stability of the bubbles. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  3. A highly selective and sensitive fluorescence assay for determination of copper(II) and cobalt(II) ions in environmental water and toner samples.

    Science.gov (United States)

    Tsai, Chia-Yi; Lin, Yang-Wei

    2013-02-21

    In this study, a highly selective and sensitive fluorescence assay has been proposed for the determination of copper(II) and cobalt(II) ions in environmental water and toner samples. In the presence of hydrogen peroxide, copper(II) reacted with a new fluorescence reagent Amplex® UltraRed (AUR), forming a fluorescence product only at pH 7.0, while the fluorescence product of cobalt(II) with AUR formed only at pH 9.0. The fluorescence signal obtained was linear with respect to the copper(II) concentration over the range of 1.6-12.0 μM (R(2) = 0.988) and was linear with respect to the cobalt(II) concentration over the range of 45.0 nM to 1.0 μM (R(2) = 0.992). The limits of detection (at a signal-to-noise ratio of 3) for copper(II) and cobalt(II) were 0.17 μM and 14.0 nM, respectively. Our present approach is simpler, faster, and more cost-effective than other techniques for the detection of copper(II) and cobalt(II) ions in environmental water samples and that of copper(II) ions in toner samples.

  4. Mercury exposure in the work place and human health: dental amalgam use in dentistry at dental teaching institutions and private dental clinics in selected cities of Pakistan.

    Science.gov (United States)

    Khwaja, Mahmood A; Nawaz, Sadaf; Ali, Saeed Waqar

    2016-03-01

    During the past two decades, mercury has come under increasing scrutiny with regard to its safety both in the general population and in occupationally exposed groups. It's a growing issue of global concern because of its adverse environmental and health impacts. Very few investigations on mercury amalgam use in the dentistry sector have been carried out in South Asia and there is little data reported on mercury contamination of indoor/outdoor air at dental sites. According to an earlier SDPI study, reported in 2013, alarmingly high mercury levels were observed in air (indoor as well as outdoor) at 11 of the 34 visited dental sites (17 dental teaching institutions, 7 general hospitals & 10 dental clinics) in five main cities of Pakistan. 88% of the sites indicated indoor mercury levels in air above the USA EPA reference level of 300 ng/m3. According to our study, carried out at 38 dental teaching institutions in 12 main cities (in Khyber Pakhtunkhwa, Punjab and Sindh provinces) of Pakistan, respondents were of the opinion that the currently offered BDS curriculum does not effectively guide outgoing dental professionals and does not provide them adequate knowledge and training about mercury/mercury amalgam and other mercury related human health and mercury waste issues. 90% of respondents supported the review and revision of the present dental curriculum offered at dental teaching institutions in the country, at the earliest. A study has also been conducted to assess the status of mercury amalgam use in private dental clinics in Gilgit, Hunza, Peshawar, Rawalpindi and Islamabad. More than 90 private dental clinics were visited and dental professionals/private clinics in-charge were interviewed during June-July, 2015. The focus areas of the study were Hg amalgam toxicity, its waste management practices and safety measures practiced among the dental practitioners. In the light of the findings described and discussed in this brief report, to safeguard public health and

  5. A highly sensitive fluorescence probe for metallothioneins based on tiron-copper complex.

    Science.gov (United States)

    Xiao, Xilin; Xue, Jinhua; Liao, Lifu; Huang, Mingyang; Zhou, Bin; He, Bo

    2015-06-15

    The fabrication of tiron-copper complex as a novel fluorescence probe for the sensitive directly detection of metallothioneins at nanomolar levels was demonstrated. In Britton-Robinson (B-R) buffer (pH 7.50), the interaction of bis(tiron)copper(II) complex cation [Cu(tiron)2](2+) and metallothioneins enhanced the fluorescence intensity of the system. The fluorescence enhancement at 347 nm was proportional to the concentration of metallothioneins. The mechanism was studied and discussed in terms of the fluorescence spectra. Under the optimal experimental conditions, at 347 nm, there was a linear relationship between the fluorescence intensity and the concentration of the metallothioneins in the range of 8.80 × 10(-9)-7.70 × 10(-7)mol L(-1), with a correlation coefficient of r=0.995 and detection limit 2.60 × 10(-9)mol L(-1). The relative standard deviation was 0.77% (n=11), and the average recovery 94.4%. The method proposed was successfully reliable, selective and sensitive in determining of trace metallothioneins in fish visceral organ samples with the results in good agreement with those obtained by HPLC.

  6. Preparation of 3D nanoporous copper-supported cuprous oxide for high-performance lithium ion battery anodes.

    Science.gov (United States)

    Liu, Dequan; Yang, Zhibo; Wang, Peng; Li, Fei; Wang, Desheng; He, Deyan

    2013-03-01

    Three-dimensional (3D) nanoporous architectures can provide efficient and rapid pathways for Li-ion and electron transport as well as short solid-state diffusion lengths in lithium ion batteries (LIBs). In this work, 3D nanoporous copper-supported cuprous oxide was successfully fabricated by low-cost selective etching of an electron-beam melted Cu(50)Al(50) alloy and subsequent in situ thermal oxidation. The architecture was used as an anode in lithium ion batteries. In the first cycle, the sample delivered an extremely high lithium storage capacity of about 2.35 mA h cm(-2). A high reversible capacity of 1.45 mA h cm(-2) was achieved after 120 cycles. This work develops a promising approach to building reliable 3D nanostructured electrodes for high-performance lithium ion batteries.

  7. Thermally Stable Siloxane Hybrid Matrix with Low Dielectric Loss for Copper-Clad Laminates for High-Frequency Applications.

    Science.gov (United States)

    Kim, Yong Ho; Lim, Young-Woo; Kim, Yun Hyeok; Bae, Byeong-Soo

    2016-04-06

    We report vinyl-phenyl siloxane hybrid material (VPH) that can be used as a matrix for copper-clad laminates (CCLs) for high-frequency applications. The CCLs, with a VPH matrix fabricated via radical polymerization of resin blend consisting of sol-gel-derived linear vinyl oligosiloxane and bulky siloxane monomer, phenyltris(trimethylsiloxy)silane, achieve low dielectric constant (Dk) and dissipation factor (Df). The CCLs with the VPH matrix exhibit excellent dielectric performance (Dk = 2.75, Df = 0.0015 at 1 GHz) with stability in wide frequency range (1 MHz to 10 GHz) and at high temperature (up to 275 °C). Also, the VPH shows good flame resistance without any additives. These results suggest the potential of the VPH for use in high-speed IC boards.

  8. Industrial experiment of copper electrolyte purification by copper arsenite

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ya-jie; XIAO Fa-xin; WANG Yong; LI Chun-hua; XU Wei; JIAN Hong-sheng; MA Yut-ian

    2008-01-01

    Copper electrolyte was purified by copper arsenite that was prepared with As2O3. And electrolysis experiments of purified electrolyte were carried out at 235 and 305 A/m2, respectively. The results show that the yield of copper arsenite is up to 98.64% when the molar ratio of Cu to As is 1.5 in the preparation of copper arsenite. The removal rates of Sb and Bi reach 74.11% and 65.60% respectively after copper arsenite is added in electrolyte. The concentrations of As, Sb and Bi in electrolyte nearly remain constant during electrolysis of 13 d. The appearances of cathode copper obtained at 235 and 305 A/m2 are slippery and even, and the qualification rate is 100% according to the Chinese standard of high-pure cathode copper(GB/T467-97).

  9. The copper intrauterine device for emergency contraception: an opportunity to provide the optimal emergency contraception method and transition to highly effective contraception.

    Science.gov (United States)

    Dermish, Amna I; Turok, David K

    2013-07-01

    Worldwide, 40% of all pregnancies are unintended. Widespread, over-the-counter availability of oral emergency contraception (EC) has not reduced unintended pregnancy rates. The EC visit presents an opportunity to initiate a highly effective method of contraception in a population at high risk of unintended pregnancy who are actively seeking to avoid pregnancy. The copper intrauterine device (IUD), the most effective method of EC, continues to provide contraception as effective as sterilization for up to 12 years, and it should be offered as the first-line method of EC wherever possible. Increased demand for and supply of the copper IUD for EC may have an important role in reducing rates of unintended pregnancy. The EC visit should include access to the copper IUD as optimal care but should ideally include access to all highly effective methods of contraception.

  10. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin.

    Science.gov (United States)

    Mahdi, S; Bahman, S; Arghavan, A B; Fatemeh, M

    2008-06-01

    Amalgam's non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05) Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  11. Clinical and Radiographic Evaluation of Pulpotomized Primary Molars Restored with Stainless Steel Crown and Amalgam

    Directory of Open Access Journals (Sweden)

    Haghgoo R.

    2011-08-01

    Full Text Available Statement of Problem: Pulpotomy is the most common pulp treatment in primary teeth. Final restoration of the pulpotomized primary molar can affect the success rate of treatment. Purpose: The aim of this study was to evaluate the success rate of formocresol pulpotomy in primary molars restored with stainless steel crowns as compared to those restored with amalgam.Materials and Method: In this randomized clinical trial study, 110 primary molars to be treated with pulpotomy were treated by a conventional pulpotomy technique. Then these teeth were randomly divided into 2 groups: amalgam and crown. 55 teeth were restored by stainless steel crown and 55 by amalgam. The clinical and radiographic evaluation was done at 6-12-24 months. The data were analyzed by Exact Fisher test.Results: During the 6 months of evaluation, no clinical and radiographic failure was seen. In the 12 months of follow up in the amalgam group, 1 case showed swelling and furcal radiolucency. During the 24 months of evaluation, mobility was seen in 2 teeth in the crown group, and in the amalgam group radiolucency was seen in 1 case, mobility in 1 case, and internal resorption in 1 tooth. Exact Fisher test showed that there was no significant difference in the success rate of pulpotomized molars restored by stainless steel crown and amalgam.Conclusion: If the tooth is selected correctly for pulpotomy, SSC and amalgam restoration can be used as the final restoration.

  12. Secondary Caries Development in in situ Gaps next to Composite and Amalgam.

    Science.gov (United States)

    Kuper, Nicolien K; Montagner, Anelise F; van de Sande, Françoise H; Bronkhorst, Ewald M; Opdam, Niek J M; Huysmans, Marie-Charlotte D J N M

    2015-01-01

    This in situ study investigated the secondary caries development in dentin in gaps next to composite and amalgam. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with an average gap of 215 µm (SD=55 µm) restored with three different materials: Filtek Supreme composite, Clearfil AP-X composite and Tytin amalgam. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 min. Before and after caries development, specimens were imaged with transversal wavelength independent microradiography, and lesion depth (LD) and mineral loss (ML) were calculated. The LD and ML of the three restoration materials were compared within patients using paired t tests (α=5%). In total 38 composite samples (Filtek n=19 and AP-X n=19) and 19 amalgam samples could be used for data analysis. AP-X composite presented the highest mean values of LD and ML of the three restorative materials. Amalgam showed statistically significantly less ML (Δ=452 µm×vol%) than the combined composite materials (p=0.036). When comparing amalgam to the separate composite materials, only AP-X composite showed higher ML (Δ=515 µm×vol%) than amalgam (p=0.034). Analysis of LD showed the same trends, but these were not statistically significant. In conclusion, amalgam showed reduced secondary caries progression in dentin in gaps compared to composite materials tested in this in situ model.

  13. [Is amalgam stained dentin a proper substrate for bonding resin composite?].

    Science.gov (United States)

    Scholtanus, J D

    2016-06-01

    After the removal of amalgam restorations, black staining of dentin is often observed, which is attributed to the penetration of corrosion products from amalgam. A study was carried out to determine whether this amalgam stained dentin is a proper substrate for bonding resin composites. A literature study and an in vitro study showed that Sn and Zn in particular are found in amalgam stained dentin, and this was the case only in demineralised dentin. In vitro, demineralised dentin acted as porte d'entrÈe for amalgam corrosion products. Bond strength tests with 5 adhesive strategies showed no differences between bond strengths to amalgam stained and to sound dentin, but did show different failure types. A clinical study showed good survival of extensive cusp replacing resin composite restorations. No failures were attributed to inadequate adhesion. It is concluded that staining of dentin by amalgam corrosion products has no negative effect upon bond strength of resin composite. It is suggested that Sn and Zn may have a beneficial effect upon dentin, thus compensating the effects of previous carious attacks, preparation trauma and physico-chemical challenges during clinical lifetime.

  14. Mercury release of amalgams with various silver contents after exposure to bleaching agent

    Science.gov (United States)

    Bahari, Mahmoud; Alizadeh Oskoee, Parnian; Savadi Oskoee, Siavash; Pouralibaba, Firoz; Morsali Ahari, Ali

    2016-01-01

    Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05). Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P dental amalgam. PMID:27429729

  15. Influence of dental biofilm on release of mercury from amalgam exposed to carbamide peroxide.

    Science.gov (United States)

    Steinberg, Doron; Blank, Ori; Rotstein, Ilan

    2003-10-15

    Tooth bleaching is a popular procedure in modern aesthetic dentistry. Bleaching agents may affect amalgam restorations by altering the release of mercury. The aim of this study was to explore the effect of biofilm-coated amalgam restorations on the release of mercury in the presence of carbamide peroxide. Samples of SDI and Valliant amalgams were submerged for either 14 days or 7 months in buffered KCl after which they were coated with saliva, bacteria, and polysaccharides. The samples were exposed to 10% carbamide peroxide (CP) for 24 h. The amount of mercury released was examined for 120 h. Results showed that most of mercury release occurred within the first 24 h, after which the release rate decreased sharply. After 120 h the release of mercury from the tested samples was minimal and similar to the control group. The presence of biofilm coating on the amalgam samples did not induce the release of mercury but tended to reduce mercury release into the surrounding environment. CP induces the release of mercury from amalgam samples. However, the presence of biofilm did not prevent large amounts of mercury release from amalgam coated with biofilms and exposed to CP. This study indicates that dental biofilm may retard the release of mercury from amalgam restorations.

  16. Screw Thread-Like Platinum-Copper Nanowires Bounded with High-Index Facets for Efficient Electrocatalysis.

    Science.gov (United States)

    Zhang, Nan; Bu, Lingzheng; Guo, Shaojun; Guo, Jun; Huang, Xiaoqing

    2016-08-10

    Introducing high-index facets into nanocrystals (NCs) is an effective way for boosting the electrocatalytic intrinsic activity. However, the established NCs with high-index facets usually have a big diameter, which makes them exhibit a very limited surface area, thus finally limited mass activity. To embody the advantage of high-index facets in enhancing electrocatalysis well, the better nanostructures should meet the requirement of both high surface area and high-density high-index facets. Herein, we report our important advances in making the unique three-dimensional screw thread-like platinum-copper (Pt-Cu) alloy nanowires (NWs) with high-density high-index facets and controlled composition. Such special NWs with a high surface area of 46.90 m(2) g(-1) exhibit much better performance than the PtCu nanoparticles (NPs) in alcohol electrooxidations. This work opens a new way for maximizing the electrocatalytic performance by introducing high-index facets into high-surface-area stable bimetallic NWs.

  17. Large low-symmetry polarons of the high-Tc, copper oxides: Formation, mobility and ordering

    Science.gov (United States)

    Bersuker, Gennadi I.; Goodenough, John B.

    1997-02-01

    A microscopic model of the evolution from antiferromagnetic insulator to superconductor on oxidation of the parent-phase (CuO 2) 2- sheets of a cuprate superconductor starts with the assumption that strong electron-lattice interactions are dominant and give a heterogeneous electronic distribution. Introduction of pseudo-Jahn-Teller vibronic coupling associated with the δ holes in the (CuO 2) (2-δ) - sheets is shown to stabilize, below a critical temperature Tp ≈ 850 K, large non-adiabatic polarons containing 5 to 7 copper centers; cooperative low-symmetry in-plane vibrations also stabilize an elastic attractive force between polarons that can overcome the longer-range Coulomb repulsion between polarons. Utilizing established parameters for isolated CuO 6 complexes gives a calculated polaron size of 5 to 7 copper centers, which compares with a measured mean size of 5.3 copper centers in underdoped samples 0 hopping. This type of motion, which is not described by conventional transport theories, gives a linear increase of the resistivity with temperature above a temperature Tϱ due to scattering of the polaron at its own border, which separates regions inside and outside the polaron of slightly different mean CuO bond length. At lower temperatures, the polaron mobility becomes activated, but at higher concentrations this change is obscured because the elastic interpolaron attractive force causes the polarons to condense into a “polaron liquid,” and below some critical temperature Td ≥ Tc the polarons undergo long-range ordering into one-dimensional polaronic stripes separated by stripes of the parent phase, which support antiferromagnetic spin fluctuations. The zig-zag polaron stripes consist of polaron pairs oriented alternately along [100] and [010] axes of a CuO 2 sheet. Formation of the ordered superstructure permits conduction of hole pairs without scattering from lattice vibrations provided there is also coupling in the third dimension between Cu

  18. Microleakage of Class II Combined Amalgam-Composite Restorations Using Different Composites and Bonding Agents

    Directory of Open Access Journals (Sweden)

    F. Sharafeddin

    2008-09-01

    Full Text Available Objective: The purpose of the present study was to assess the microleakage of composite restorations with and without a cervical amalgam base and to compare the results of dif-ferent composites and bonding agents.Materials and Methods: One hundred and twenty mesio-occlusal (MO and disto-occlusal (DO Class II cavities were prepared on sixty extracted permanent premolar teeth. The teeth were randomly divided into four groups of 30 and restored as follows:In group A, the mesio-occlusal cavity (MO, Scotchbond multi purpose plus + Z250 and in the disto-occlusal (DO cavity, Prompt-L-Pop + Z250 were applied. As for group B, in the MO and DO cavities, Clearfil SE Bond + Clearfil APX, and varnish + amalgam (In box + Clearfil SE Bond + Clearfil APX were used respectivelywhile in group C; the teeth were restored with amalgam and varnish mesio-occlusally and with amalgam only disto-occlusally. As for group D, varnish + amalgam (in box + Scotchbond multi purpose plus + Z250 were applied mesio-occlusally and Varnish + Amalgam (in box + Prompt–L–Pop + Z250 disto-occlusally.Marginal leakage was assessed by the degree of dye penetration into various sections of the restored teeth. Chi-square and Fisher's exact tests were used for data analysis.Results: Microleakage in gingival margin was more than that in occlusal margin (P<0.05 and microleakage of combined amalgam-composite restorations was significantly lower than that of conventional composite and amalgam restorations.Conclusion: Marginal microleakage decreased by using amalgam at the base of the box in Class II composite restorations.

  19. Design and evaluation of a filter-based chairside amalgam separation system

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Mark E. [Naval Institute for Dental and Biomedical Research, 310A B Street, Great Lakes, Illinois 60088 (United States)], E-mail: mark.stone@yahoo.com; Cohen, Mark E.; Berry, Denise L.; Ragain, James C. [Naval Institute for Dental and Biomedical Research, 310A B Street, Great Lakes, Illinois 60088 (United States)

    2008-06-15

    This study evaluated the ability of a chairside filtration system to remove particulate-based mercury (Hg) from dental-unit wastewater. Prototypes of the chairside filtration system were designed and fabricated using reusable filter chambers with disposable filter elements. The system was installed in five dental operatories utilizing filter elements with nominal pore sizes of 50{mu}m, 15{mu}m, 1{mu}m, 0.5{mu}m, or with no system installed (control). Daily chairside wastewater samples were collected on ten consecutive days from each room and brought to the laboratory for processing. After processing the wastewater samples, Hg concentrations were determined with cold vapor atomic absorption spectrometry (USEPA method 7470A). Filter systems were exchanged after ten samples were collected so that all five of the configurations were evaluated in each room (with assignment order balanced by a Latin Square). The numbers of surfaces of amalgam placed and removed per day were tracked in each room. In part two, new filter systems with the 0.5{mu}m filter elements were installed in the five dental operatories and vacuum levels at the high-velocity evacuation cannula tip were measured with a vacuum gauge. In part three of the study, the chairside filtration system utilizing 0.5{mu}m and 15{mu}m filter elements was evaluated utilizing the ISO 11143 testing protocol, a laboratory test of amalgam separator efficiency utilizing amalgam samples of known particle size distribution. Mean Hg per chair per day (no filter installed) was 1087.38mg (SD = 993.92mg). Mean Hg per chair per day for the 50{mu}m, 15{mu}m, 1{mu}m, 0.5{mu}m filter configurations was 79.13mg (SD = 71.40mg), 23.55mg (SD = 23.25mg), 17.68mg (SD = 17.35mg), and 4.25mg (SD = 6.35mg), respectively (n = 50 for all groups). Calculated removal efficiencies from the clinical samples were 92.7%, 97.8%, 98.4%, and 99.6%, respectively. ANCOVA on data from the four filter groups, with amalgam-surfaces-removed included as a

  20. Three-Dimensional Reduced Graphene Oxide Network on Copper Foam as High-performance Supercapacitor Electrodes

    DEFF Research Database (Denmark)

    Dey, Ramendra Sundar; Chi, Qijin

    - integrated supercapacitor electrode s (3DrGO@Cuf) [1] . The method involves a two - step procedure, self - assembly of graphene oxide (GO) nanosheets on Cuf and electrochemical reduction of GO into rGO. We have systematically characterized as - synthesized materials using AFM, SEM and XRD to reveal......E lectrochemically generated copper foam (Cuf) could serve as an effective template for fabrication of three - dimensional (3D) reduced graphe n e oxide (rGO) network s. Here we present a facile approach to preparation of 3D rGO network supported by Cuf a s binder - free and current collector...... knowledge, we may have achieve d the highest specific capacitance with 3DrGO@Cuf electrodes among reported pure 3D graphene materials to date (i.e. 3D graphene materials without doping additional capacitive species ) [2 , 3 ]...

  1. Shape-controlled synthesis of palladium and copper superlattice nanowires for high-stability hydrogen sensors

    Science.gov (United States)

    Yang, Dachi; Carpena-Núñez, Jennifer; Fonseca, Luis F.; Biaggi-Labiosa, Azlin; Hunter, Gary W.

    2014-01-01

    For hydrogen sensors built with pure Pd nanowires, the instabilities causing baseline drifting and temperature-driven sensing behavior are limiting factors when working within a wide temperature range. To enhance the material stability, we have developed superlattice-structured palladium and copper nanowires (PdCu NWs) with random-gapped, screw-threaded, and spiral shapes achieved by wet-chemical approaches. The microstructure of the PdCu NWs reveals novel superlattices composed of lattice groups structured by four-atomic layers of alternating Pd and Cu. Sensors built with these modified NWs show significantly reduced baseline drifting and lower critical temperature (259.4 K and 261 K depending on the PdCu structure) for the reverse sensing behavior than those with pure Pd NWs (287 K). Moreover, the response and recovery times of the PdCu NWs sensor were of ~9 and ~7 times faster than for Pd NWs sensors, respectively.

  2. High efficiency pollutant removal with the Moving-Bed Copper Oxide Process

    Energy Technology Data Exchange (ETDEWEB)

    Pennline, H.W.; Hoffman, J.S.; Yeh, J.T. [Dept. of Energy, Pittsburgh, PA (United States). Pittsburgh Energy Technology Center; Resnik, K.P.; Vore, P.A. [Gilbert Commonwealth, Inc., Pittsburgh, PA (United States)

    1995-12-31

    Dry, regenerable flue gas cleanup techniques that use a sorbent can have various advantages, such as simultaneous removal of pollutants, production of a salable by-product, and low costs when compared to commercially available scrubbing technology. Due to the temperature of reaction, the placement of the process into an advanced power system could actually increase the thermal efficiency of the plant. One such technique, the Moving-Bed Copper Oxide Process, is capable of simultaneously removing sulfur oxides and nitric oxides within the reactor system. A parametric study of the process was conducted on a life-cycle test system. All process steps, including absorption and regeneration, were integrated into this life-cycle test system so that continuous, long-term operation of the total process cold be experimentally evaluated. The effects of absorption temperature, sorbent and gas residence times, and inlet SO{sub 2} and NO{sub x} concentration on removal efficiencies and overall operational performance are discussed.

  3. High packing density laser diode stack arrays using Al-free active region laser bars with a broad waveguide and discrete copper microchannel-cooled heatsinks

    Institute of Scientific and Technical Information of China (English)

    Zhigang Liu; Gaozhan Fang; Kecheng Feng

    2009-01-01

    A high packing density laser diode stack array is developed utilizing Al-free active region laser bars with a broad waveguide and discrete copper microchannel-cooled heatsinks. The microchannel cooling technology leads to a 10-bar laser diode stack array having the thermal resistance of 0.199 ℃/W, and enables the device to be operated under continuous-wave (CW) condition at an output power of 1200 W. The thickness of the discrete copper heatsink is only 1.5 mm, which results in a high packing density and a small bar pitch of 1.8 mm.

  4. Functionally generated amalgam stops for single complete denture: A case report

    Directory of Open Access Journals (Sweden)

    Pravinkumar G Patil

    2009-01-01

    Full Text Available Single complete denture opposing natural dentition is a common occurrence in clinical practice. This article reports a case of a single complete denture with a technique of occlusal refinement by func-tionally generated amalgam stops condensed in prepared resin teeth after initial balancing of the den-ture with semi-adjustable articulator. This technique provides intimacy of contact in all excursions by carving the amalgam in plastic stage. Amalgam stops improve the efficiency of the resin teeth. Den-tures fabricated using this technique require fewer and simpler post-insertion adjustments.

  5. Investigation of the mechanism of mercury removal from a silver dental amalgam alloy

    Directory of Open Access Journals (Sweden)

    M. DJURDJEVIC

    2004-12-01

    Full Text Available An investigation of silver dental amalgam decomposition and the mercury removal mechanism was performed. The decomposition process was analysed during thermal treatment in the temperature interval from 400 °C to 850 °C and for times from 0.5 to 7.5 h. The chemical compositions of the silver dental amalgam alloy and the treated alloy were tested and microstructure analysis using optical and scanning electron microscopy was carried out. The phases were identified using energy disperse electron probe microanalysis. A mechanism for the mercury removal process from silver dental amalgam alloy is suggested.

  6. Facile and Cost-Effective Synthesis and Deposition of a YBCO Superconductor on Copper Substrates by High-Energy Ball Milling

    Science.gov (United States)

    Alami, Abdul Hai; Assad, Mhd Adel; Aokal, Camilia

    2016-09-01

    The article investigates the synthesis and deposition of YBCO on a copper substrate for various functional purposes. The superconductor is first prepared by mechanically alloying elemental components (yttrium, barium, and copper) for 50 hours in a high-energy ball mill with subsequent protocol of heat treatment in an oxygen-rich atmosphere to arrive at stoichiometric ratios of YBa2Cu3O7. The material is then deposited on a thin copper substrate also by ball milling under various parameters of rotational speed and deposition time to select the best and most homogenous substrate coverage. Atomic force microscopy has confirmed the desired results, and other microstructural, thermal, and electrical techniques are used to characterize the obtained material. High-energy ball milling proved to be a versatile means to synthesize and deposit the material in a straightforward manner and controllable parameters for different deposit thicknesses and coverages.

  7. Facile and Cost-Effective Synthesis and Deposition of a YBCO Superconductor on Copper Substrates by High-Energy Ball Milling

    Science.gov (United States)

    Alami, Abdul Hai; Assad, Mhd Adel; Aokal, Camilia

    2016-12-01

    The article investigates the synthesis and deposition of YBCO on a copper substrate for various functional purposes. The superconductor is first prepared by mechanically alloying elemental components (yttrium, barium, and copper) for 50 hours in a high-energy ball mill with subsequent protocol of heat treatment in an oxygen-rich atmosphere to arrive at stoichiometric ratios of YBa2Cu3O7. The material is then deposited on a thin copper substrate also by ball milling under various parameters of rotational speed and deposition time to select the best and most homogenous substrate coverage. Atomic force microscopy has confirmed the desired results, and other microstructural, thermal, and electrical techniques are used to characterize the obtained material. High-energy ball milling proved to be a versatile means to synthesize and deposit the material in a straightforward manner and controllable parameters for different deposit thicknesses and coverages.

  8. Highly efficient aerobic oxidation of alcohols by using less-hindered nitroxyl-radical/copper catalysis: optimum catalyst combinations and their substrate scope.

    Science.gov (United States)

    Sasano, Yusuke; Kogure, Naoki; Nishiyama, Tomohiro; Nagasawa, Shota; Iwabuchi, Yoshiharu

    2015-04-01

    The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts.

  9. High Cobalt, Copper And Zinc Smelting Practice Of High Raw Material%高钴、高铜锌原料冶炼的实践

    Institute of Scientific and Technical Information of China (English)

    韦庭胜

    2012-01-01

    This article mainly introduced in the process of zinc hydrometallurgy how successful treatment of high cobalt, copper refined zinc and treatment effect. Through the introduction of cobalt, copper impurity in the process of zinc hydrometallurgy of zinc electrolysis process hazard and affect the quality of refined zinc, and cobalt, copper impurity in the process of zinc hydrometallurgy leaching, purification, electrolytic process behavior, make the production process and process conditions. Simple description of roasting, leaching process conditions and basis. Focuses on the purification mechanism, antimony trioxide purification method mechanism. Presents a selection of inverse antimony trioxide purification method basis, Narrative Choice purification process and technological conditions. At the same time for cobalt impurities high case, prevent cobalt impurities accumulation in production system, puts forward the method and effect of cobalt impurities control. Finally, introduces the application of formulation of the production process and application in hydrometallurgical zinc production in treatment of high cobalt, some experience of high copper.%文章主要介绍在湿法炼锌中如何成功处理高钴、高铜精锌矿及处理效果。通过介绍钴、铜杂质在湿法炼锌中电解过程的危害及对锌锭质量的影响,以及分析了精锌矿中钴、铜杂质在湿法炼锌中浸出、净化、电解过程中的行为,制定了生产工艺流程和工艺条件。简单地叙述沸腾焙烧、浸出的工艺条件和制定依据。重点叙述净化工艺机理、锑盐净化法机理。提出了选择逆锑盐净化法的依据,叙述所选择净化工艺流程和工艺条件。同时针对钴杂质特高情况下,防止钴杂质在生产系统积累,提出了钴杂质控制的方法及效果。最后介绍应用制定的工艺生产应用效果及在湿法炼锌生产中处理高钴、高铜矿几点心得。

  10. Laser cladding of stainless steel with a copper-silver alloy to generate surfaces of high antimicrobial activity

    Science.gov (United States)

    Hans, Michael; Támara, Juan Carlos; Mathews, Salima; Bax, Benjamin; Hegetschweiler, Andreas; Kautenburger, Ralf; Solioz, Marc; Mücklich, Frank

    2014-11-01

    Copper and silver are used as antimicrobial agents in the healthcare sector in an effort to curb infections caused by bacteria resistant to multiple antibiotics. While the bactericidal potential of copper and silver alone are well documented, not much is known about the antimicrobial properties of copper-silver alloys. This study focuses on the antibacterial activity and material aspects of a copper-silver model alloy with 10 wt% Ag. The alloy was generated as a coating with controlled intermixing of copper and silver on stainless steel by a laser cladding process. The microstructure of the clad was found to be two-phased and in thermal equilibrium with minor Cu2O inclusions. Ion release and killing of Escherichia coli under wet conditions were assessed with the alloy, pure silver, pure copper and stainless steel. It was found that the copper-silver alloy, compared to the pure elements, exhibited enhanced killing of E. coli, which correlated with an up to 28-fold increased release of copper ions. The results show that laser cladding with copper and silver allows the generation of surfaces with enhanced antimicrobial properties. The process is particularly attractive since it can be applied to existing surfaces.

  11. Effect of high dietary copper on growth, antioxidant and lipid metabolism enzymes of juvenile larger yellow croaker Larimichthys croceus

    Directory of Open Access Journals (Sweden)

    Fanxing Meng

    2016-05-01

    Full Text Available A study was carried out to test the responses of juvenile larger yellow croaker Larimichthys croceus to high Cu intake. Experimental diets were formulated containing three levels of Cu: low Cu (3.67 mg/kg, middle Cu (13.65 mg/kg and high Cu (25.78 mg/kg, and each diet were fed to large yellow croaker in triplicate for 10 weeks. Final body weight, weight gain and feed intake were the lowest in high Cu group, but hepatosomatic index was the highest; Cu concentrations in the whole-body, muscle and liver of fish fed low Cu diet was the lowest; Liver superoxide dismutase, catalase and glutathione peroxidase activities in fish fed high Cu diet were lower than those in fish fed other diets; The higher content of liver thiobarbituric acid reactive substance content was found in high Cu group, followed by middle Cu group, and the lowest in low Cu group; Liver 6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, malic enzyme, isocitrate dehydrogenase and fatty acid synthase activities were the lowest in high Cu group, but lipoprotein lipase activity was the highest. This study indicated that high copper intake reduced growth of juvenile larger yellow croaker, inhibited activities of antioxidant enzymes and lipid synthetases, and led to energy mobilization.

  12. Highly sensitive photodetectors based on hybrid 2D-0D SnS{sub 2}-copper indium sulfide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yun; Zhan, Xueying; Xu, Kai; Yin, Lei; Cheng, Zhongzhou; Jiang, Chao; Wang, Zhenxing, E-mail: wangzx@nanoctr.cn, E-mail: hej@nanoctr.cn; He, Jun, E-mail: wangzx@nanoctr.cn, E-mail: hej@nanoctr.cn [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China)

    2016-01-04

    Both high speed and efficiency of photoelectric conversion are essential for photodetectors. As an emerging layered metal dichalcogenide (LMD), tin disulfide owns intrinsic faster photodetection ability than most other LMDs but poor light absorption and low photoelectric conversion efficiency. We develop an efficient method to enhance its performance by constructing a SnS{sub 2}-copper indium sulfide hybrid structure. As a result, the responsivity reaches 630 A/W, six times stronger than pristine SnS{sub 2} and much higher than most other LMDs photodetectors. Additionally, the photocurrents are enhanced by more than 1 order of magnitude. Our work may open up a pathway to improve the performance of photodetectors based on LMDs.

  13. Highly sensitive detection of copper ions by densely grafting fluorescein inside polyethyleneimine core-silica shell nanoparticles.

    Science.gov (United States)

    Qiao, Yali; Zheng, Xingwang

    2015-12-21

    In this work, polyethyleneimine (PEI) core-silica shell nanoparticles were synthesized and used for densely grafting fluorescent receptor units inside the core of these particles to result in multi-receptor units collectively sensing a target. Herein, copper ion quenching of the fluorescence intensity of a fluorescein isothiocyanate (FITC) system was selected as a model to confirm our proof-of-concept strategy. Our results showed that, compared to free FITC in solution, a 10-fold enhancement of the Stern-Volmer constant value for Cu(2+) quenching of the fluorescence intensity of the grafted state of FITC in PEI core-silica shell nanoparticles was achieved. Furthermore, compared to a previous collective sensing scheme by densely grafting fluorescent receptor units on a silica nanoparticle surface, the proposed scheme, which grafted fluorescent receptor units inside a polymer nano-core, was simple, highly efficient and presented higher sensitivity.

  14. A highly selective copper-indium bimetallic electrocatalyst for the electrochemical reduction of aqueous CO2to CO

    KAUST Repository

    Rasul, Shahid

    2014-12-23

    The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. DFT calculations showed that the In preferentially located on the edge sites rather than on the corner or flat sites and that the d-electron nature of Cu remained almost intact, but adsorption properties of neighboring Cu was perturbed by the presence of In. This preparation of non-noble metal alloy electrodes for the reduction of CO2 provides guidelines for further improving electrocatalysis.

  15. Copper Nanoparticle/Multiwalled Carbon Nanotube Composite Films with High Electrical Conductivity and Fatigue Resistance Fabricated via Flash Light Sintering.

    Science.gov (United States)

    Hwang, Hyun-Jun; Joo, Sung-Jun; Kim, Hak-Sung

    2015-11-18

    In this work, multiwalled carbon nanotubes (MWNTs) were employed to improve the conductivity and fatigue resistance of flash light sintered copper nanoparticle (NP) ink films. The effect of CNT weight fraction on the flash light sintering and the fatigue characteristics of Cu NP/CNT composite films were investigated. The effect of carbon nanotube length was also studied with regard to enhancing the conductivity and fatigue resistance of flash light sintered Cu NP/CNT composite films. The flash light irradiation energy was optimized to obtain high conductivity Cu NP/CNT composite films. Cu NP/CNT composite films fabricated via optimized flash light irradiation had the lowest resistivity (7.86 μΩ·cm), which was only 4.6 times higher than that of bulk Cu films (1.68 μΩ·cm). It was also demonstrated that Cu NP/CNT composite films had better durability and environmental stability than those of Cu NPs only.

  16. Field evaluation of mercury vapor analytical methods: comparison of the "double amalgam method" and ISO 17733.

    Science.gov (United States)

    Takaya, Mitsutoshi; Joeng, Jee Yeon; Ishihara, Nobuo; Serita, Fumio; Kohyama, Norihiko

    2006-04-01

    In this study, a gold amalgam method called the "Double amalgam method" was compared with the ISO 17733 method for mercury vapor analysis method. In terms of sensitivity and ease of operation, the amalgamation method is superior to the oxidation method. Two parallel samplings were carried out in this research at a button battery factory, where the mercury vapor level in the air was about 0.001 mg/m3 and at a fluorescent lamp factory, where the mercury vapor level was about 0.015 mg/m3. In the both cases, the measured values of the two showed good agreement with each other. As these two workplaces represent typical mercury levels in industries today, the double amalgam method is applicable to working environment measurement.

  17. Managing the phase-down of amalgam: Part I. Educational and training issues.

    Science.gov (United States)

    Lynch, C D; Wilson, N H F

    2013-08-01

    Following the recently agreed Minamata Convention, a phase-down in the use of dental amalgam will become a priority for the profession. With a lead-in period of a number of years, important changes in the mind-set of the profession are required to ensure that patient safety is not compromised. Posterior composites have been a viable, and in many cases preferable, alternative to amalgam for many years. However, notwithstanding considerable developments in dental school teaching on the application and placement of posterior composites, growing evidence to support the use of composites in the restoration of posterior teeth and advances in composite systems, many practitioners remain reluctant to place composite rather than amalgam. This paper considers the present and future use of posterior composites and highlights ways in which dental school teaching and continuing professional development (CPD) may contribute to the successful phase-down, and now inevitable discontinuation, in the use of dental amalgam.

  18. Amalgam contact hypersensitivity lesion: an unusual presentation-report of a rare case.

    Science.gov (United States)

    Ramnarayan, Bk; Maligi, Pm; Smitha, T; Patil, Us

    2014-09-01

    Amalgam or its components may cause Type IV hypersensitivity reactions on the oral mucosa. These amalgam contact hypersensitivity lesions (ACHL) present as white striae and plaques, erythematous, erosive, atrophic, or ulcerative lesions. Postinflammatory pigmentation in such lesions and pigmentation due to amalgam incorporation in the soft tissue have been reported in the literature. However, ACHL presenting primarily as a black pigmented lesion is extremely rare if not reported. The clinician should be aware of one such presentation of ACHL; we report a unique case of ACHL in a 30-year-old female with such a pigmented lesion in close contact with amalgam restorations. The lesion regressed considerably in a year after replacement of the restoration with posterior composites.

  19. ON THE WEIGHTED VARIABLE EXPONENT AMALGAM SPACE W (Lp(x), Lqm)

    Institute of Scientific and Technical Information of China (English)

    A.Turan GURKANLI; Ismail AYDIN

    2014-01-01

    In [4] , a new family W (Lp(x), Lqm) of Wiener amalgam spaces was defined and investigated some properties of these spaces, where local component is a variable exponent Lebesgue space Lp(x) (R) and the global component is a weighted Lebesgue space Lqm (R). This present paper is a sequel to our work [4]. In Section 2, we discuss necessary and sufficient conditions for the equality W Lp(x), Lqm=Lq (R) . Later we give some characterization of Wiener amalgam space WLp(x), Lqm. In Section 3 we define the Wiener amalgam space W FLp(x),Lq m and investigate some properties of this space, where F Lp(x) is the image of Lp(x) under the Fourier transform. In Section 4, we discuss boundedness of the Hardy-Littlewood maximal operator between some Wiener amalgam spaces.

  20. Daya Antibakteri Bahan Tumpat Amalgam dan Resin Komposit Berfluor Terhadap Bakteri Streptococcus Mutans Serotipe KPSK2

    Directory of Open Access Journals (Sweden)

    Dewa Ayu Nyoman Putri Artiningsih

    2015-09-01

    Full Text Available This research was carried out to study the difference in the antibacterial capacity of two kinds of filling materials, namely amalgam and composite resin, on S. mutans KPSK2 bacteria with different times of treatment. In total, 48 amalgam and composite resin samples each were prepared and then divided into four groups of treatment. Of each group, 6 samples were used to count the number of bacterial colonies and 6 samples to count the right obstacle zone. The results show that the best antibacterial capacity of composite resin occurred within one week, while for amalgam the best performance appears within one day. The antibacterial capacity of fluorine containing composites is stronger than that of amalgam for a time of 1 to 2 weeks.

  1. New science challenges old notion that mercury dental amalgam is safe.

    Science.gov (United States)

    Homme, Kristin G; Kern, Janet K; Haley, Boyd E; Geier, David A; King, Paul G; Sykes, Lisa K; Geier, Mark R

    2014-02-01

    Mercury dental amalgam has a long history of ostensibly safe use despite its continuous release of mercury vapor. Two key studies known as the Children's Amalgam Trials are widely cited as evidence of safety. However, four recent reanalyses of one of these trials now suggest harm, particularly to boys with common genetic variants. These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from dental amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best. Throughout the world, efforts are underway to phase down or eliminate the use of mercury dental amalgam.

  2. [Management of wastes from dental amalgam by dentists in Burkina Faso and Morocco].

    Science.gov (United States)

    Chala, S; Sawadogo, A; Sakout, M; Abdallaoui, F

    2012-12-01

    Dental amalgam is a metallic restorative material that is used for direct filling of carious lesions since many years. The use of this material generates solid and particulate wastes that present potential challenges to the environment. This study was carried out to assess amalgam use and waste management protocols practiced by Moroccan and Burkinabe dentists. A cross-sectional study was made of 79 in Rabat, Sale and Temara in Morocco and 56 in Ouagadougou, Bobo-Dioulasso in Burkina-Faso. The results showed that 69.5% of dental amalgam waste in Morocco vs 49.9% in Burkina-Faso was disposed with household waste which is a problem for both the environment and a risk to human being. Proper methods of dental amalgam waste disposal should be carried out to prevent indirect mercury poisoning for human.

  3. Cracked mercury dental amalgam as a possible cause of fever of unknown origin: a case report

    Directory of Open Access Journals (Sweden)

    Bamonti Fabrizia

    2008-03-01

    Full Text Available Abstract Introduction Sudden fever of unknown origin is quite a common emergency and may lead to hospitalization. A rise in body temperature can be caused by infectious diseases and by other types of medical condition. This case report is of a woman who had fever at night for several days and other clinical signs which were likely related to cracked dental mercury amalgam. Case presentation A healthy women developed fever many days after had cracked a mercury dental amalgam filling. Blood tests evidenced increased erythrocyte sedimentation rate, anemia and elevated white cell count; symptoms were headache and palpitations. Blood tests and symptoms normalized within three weeks of removal of the dental amalgam. Conclusion This case highlights the possible link between mercury vapor exposure from cracked dental amalgam and early activation of the immune system leading to fever of unknown origin.

  4. Treatment of amalgam tattoo with a subepithelial connective tissue graft and acellular dermal matrix.

    Science.gov (United States)

    Thumbigere-Math, Vivek; Johnson, Deborah K

    2014-04-01

    A 54-year-old female was referred for management of a large amalgam tattoo involving the alveolar mucosa between teeth #6 and #9. The lesion had been present for over 20 years following endodontic treatment of teeth #7 and #8. A two-stage surgical approach was used to remove the pigmentation, beginning with removal of amalgam fragments from the underlying bone and placement of a subepithelial connective tissue graft and acellular dermal matrix to increase soft tissue thickness subadjacent to the amalgam. Following 7 weeks of healing, gingivoplasty was performed to remove the overlying pigmented tissue. At the 21-month follow-up appointment, the patient exhibited naturally appearing soft tissue with no evidence of amalgam tattoo.

  5. Bond strength comparison of amalgam repair protocols using resin composite in situations with and without dentin exposure.

    Science.gov (United States)

    Ozcan, Mutlu; Schoonbeek, Geert; Gökçe, Bülent; Cömlekoglu, Erhan; Dündar, Mine

    2010-01-01

    The replacement of defective amalgam restorations leads to loss of tooth material and weakens the tooth, creating an increased risk of cusp fracture. The repair of such defects is a minimal intervention technique. The current study compared the repair bond strengths of a resin composite to amalgam and an amalgam-dentin complex after various surface conditioning methods. The specimens (N = 50) consisted of sound human canines with cylindrical preparations (diameter: 2.3 mm, depth: 3 mm) with amalgam-dentin complex (N = 30, n = 10/per group) and two groups with amalgam only (N = 20, n = 10/per group). The teeth were embedded in auto-polymerized polymethylmethacrylate (PMMA). The preparations were filled with non-Gamma 2 amalgam. The enamel was removed to expose dentin. The specimens with the amalgam-dentin complex were randomly assigned to one of the following conditioning methods: Group 1: Silicacoating amalgam, etching dentin, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both; Group 2: Etching dentin, silicacoating amalgam, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both and Group 3: Etching dentin, primer/bonding on dentin, opaquer, resin composite. The specimens with only amalgam were assigned to one of the following conditioning methods: Group 4: Silicacoating, silane application, opaquer, resin composite and Group 5: Opaquer, resin composite. For the two control groups, where no dentin was involved (Groups 4 and 5), bonding was achieved only on amalgam and Group 5 had no conditioning. The specimens were kept in water at 37 degrees C for five weeks before bond strength (MPa +/- SD) testing (Universal Testing Machine). After debonding, the failure types were analyzed. The results were significantly affected by the surface conditioning method (ANOVA). Only dentin conditioning (Group 3) showed the highest bond strength (39.9 +/- 14). The unconditioned control

  6. Copper Aluminum Nano Junction Normal Temperature Processes and Methods Applied to the LED High Heat Transfer Performance

    Directory of Open Access Journals (Sweden)

    Ming-Wen Wang

    2014-03-01

    Full Text Available High-power light-emitting diodes (LED have extremely broad applications. However, with the job requirements of high-brightness and high color temperature from light-emitting diodes, it must be followed to enlarge the operating current, thus heating up more rapidly. If its heat dissipation problem cannot be effectively solved, operation will be prone to bring about color shift, and it may even considerably shorten its life. Moreover, application value will therefore be greatly reduced. So in order to enhance the high-power LED luminous brightness and life to cope with the future development needs of high-power LED components, it is necessary to replace the use of conductive silver paste to stick thermally conductive Cu slug fixing grain and lead frame heat dissipation aluminum sheet. This is done by directly bonding thermally conductive Cu slug with pure aluminum, the formation of highly efficient direct heat conduction cooling structure. Therefore the topic points at the crux of the LED heat dissipation difficulty, puts forward of copper and aluminum bonding technology in the ordinary temperature and pressure, method to effectively improve thermal conductivity performance between LED die bond Cu slug and joining aluminum cooling module. This will ultimately make the LED's operation and applications perfect.

  7. Thermal behavior of silicon-copper micro vapor chamber for high power LEDs

    Science.gov (United States)

    Luo, Yi; Li, Zhi-xin; Zhou, Chuan-peng; Wang, Xiao-dong; You, Bo

    2016-03-01

    Micro vapor chamber (MVC) for light emitting diodes (LEDs) can be designed and fabricated to enhance the heat dissipation efficiency and improve the reliability. In this paper, we used photoresist SU-8 and electroforming copper (Cu) to fabricate three kinds of wick structures, which are star, radiation and parallel ones, and the substrate is silicon with thickness of 0.5 mm. Electroforming Cu on silicon to make micro wick structure was a critical step, the ampere-hour factor was used, and accordingly the electroforming time was predicted. The composition of electroforming solution and parameters of electroforming were optimized too. After charging and packaging, thermal behavior tests were carried out to study the heat dissipation performance of MVCs. When the input power was 8 W, the parallel wick structure reached the equivalent temperature of 69.0 °C in 226 s, while the others were higher than that. The experimental results prove that the wick structures have significant influence on the heat transfer capability of MVCs.

  8. Shape-controlled synthesis of palladium and copper superlattice nanowires for high-stability hydrogen sensors.

    Science.gov (United States)

    Yang, Dachi; Carpena-Núñez, Jennifer; Fonseca, Luis F; Biaggi-Labiosa, Azlin; Hunter, Gary W

    2014-01-20

    For hydrogen sensors built with pure Pd nanowires, the instabilities causing baseline drifting and temperature-driven sensing behavior are limiting factors when working within a wide temperature range. To enhance the material stability, we have developed superlattice-structured palladium and copper nanowires (PdCu NWs) with random-gapped, screw-threaded, and spiral shapes achieved by wet-chemical approaches. The microstructure of the PdCu NWs reveals novel superlattices composed of lattice groups structured by four-atomic layers of alternating Pd and Cu. Sensors built with these modified NWs show significantly reduced baseline drifting and lower critical temperature (259.4 K and 261 K depending on the PdCu structure) for the reverse sensing behavior than those with pure Pd NWs (287 K). Moreover, the response and recovery times of the PdCu NWs sensor were of ~9 and ~7 times faster than for Pd NWs sensors, respectively.

  9. High-mobility solution-processed copper phthalocyanine-based organic field-effect transistors

    Directory of Open Access Journals (Sweden)

    Nandu B Chaure, Andrew N Cammidge, Isabelle Chambrier, Michael J Cook, Markys G Cain, Craig E Murphy, Chandana Pal and Asim K Ray

    2011-01-01

    Full Text Available Solution-processed films of 1,4,8,11,15,18,22,25-octakis(hexyl copper phthalocyanine (CuPc6 were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs in the bottom-gate configurations using chemical vapour deposited silicon dioxide (SiO2 as gate dielectrics. The surface treatment of the gate dielectric with a self-assembled monolayer of octadecyltrichlorosilane (OTS resulted in values of 4×10−2 cm2 V−1 s−1 and 106 for saturation mobility and on/off current ratio, respectively. This improvement was accompanied by a shift in the threshold voltage from 3 V for untreated devices to -2 V for OTS treated devices. The trap density at the interface between the gate dielectric and semiconductor decreased by about one order of magnitude after the surface treatment. The transistors with the OTS treated gate dielectrics were more stable over a 30-day period in air than untreated ones.

  10. Results of crack-arrest tests on two irradiated high-copper welds

    Energy Technology Data Exchange (ETDEWEB)

    Iskander, S.K.; Corwin, W.R.; Nanstead, R.K. (Oak Ridge National Lab., TN (USA))

    1990-12-01

    The objective of this study was to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288{degree}C to an average fluence of 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). Evaluation of the results shows that the neutron-irradiation-induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves (for the range of test temperatures covered) did not seem to have been altered by irradiation compared to those of the ASME K{sub Ia} curve. 9 refs., 21 figs., 10 tabs.

  11. Achieving High Strength Joint of Pure Copper Via Laser-Cold Metal Transfer Arc Hybrid Welding

    Science.gov (United States)

    Chen, Yulong; Chen, Cong; Gao, Ming; Zeng, Xiaoyan

    2016-06-01

    Fiber laser-cold metal transfer arc hybrid welding of pure copper was studied. Weld porosity was tested by X-ray nondestructive testing. Microstructure and fracture features were observed by scanning electron microscopy. Mechanical properties were evaluated by cross weld tensile test. Full penetrated and continuous welds were obtained by hybrid welding once the laser power reached 2 kW, while they could not be obtained by laser welding alone, even though the laser power reached 5 kW. The ultimate tensile strength (UTS), the yield strength (YS), and the elongation of the best hybrid weld material were up to 227, 201 MPa, and 21.5 pct, respectively. The joint efficiencies in UTS and YS of hybrid weld were up to 84 and 80 pct of the BM, respectively. The fracture location changes from the fusion zone to the heat-affected zone with the increase of laser power. Besides, the mechanisms of process stability and porosity suppression were clarified by laser-arc interaction and pool behavior. The strengthening mechanism was discussed by microstructure characteristics.

  12. The amalgam of faith and reason: Euclid’s Elements and the scientific thinker

    DEFF Research Database (Denmark)

    Andrade-Molina, Melissa; Valero, Paola; Ravn, Ole

    2017-01-01

    child intertwines with what was ought to be the ‘scientific thinker’ to Christianity. We focus on how Euclidean geometry, taken as a proper method of inquiry amalgamated with the Christian worldview to provide explanations about the natural world. In modern education, the core of this amalgamation...... continues connecting reason with faith, and science with Platonic views of mathematics. The effect of power is the making of the Modern scientific thinker....

  13. Marginal behaviour of self-etch adhesive/composite and combined amalgam-composite restorations.

    Science.gov (United States)

    Kournetas, Nikos; Kakaboura, Afrodite; Giftopoulos, Dimitrios; Chakmachi, Magdad; Rahiotis, Christos; Geis-Gerstorfer, J

    2010-06-01

    The aim of this study was to compare the marginal and internal adaptation in self-etching adhesive (SEA)/composite restorations with combined amalgam-resin-based composite restorations in the proximal box with and without bonding agent beneath amalgam both before and after load-cycling. Class II restorations, were manufactured as following a) Bonding agent (Clearfil Liner Bond 2V, Kuraray) beneath amalgam (Tytin, SDS Kerr) and resin-based composite (Clearfil APX, Kuraray) with SEA, b) Amalgam without bonding agent and resin-based composite with SEA and c) Resin-based composite with SEA. Each group divided into two equal subgroups (n=8). Marginal and internal adaptation of first subgroup evaluated after 7-day water storage and of the second after load-cycling in chewing simulator for 1.2 x 10(6) cycles. Marginal and internal adaptation at cervical and amalgam-composite sites evaluated by videomicroscope and ranked as "excellent"/"non-excellent". Slices of restorations examined under optical microscope to determine the quality of bonding layer. Defects in cervical adaptation observed in the three restorative techniques examined prior loading. Amalgam-composite combination in proximal surface provided comparable marginal and internal adaptation results at cervical wall, to self-etching-composite combination. Portion (25-37.5%) of amalgam-resin-based composite interfaces in proximal box presented no perfect sealing. The application of bonding agent beneath amalgam resulted in relatively inferior cervical adaptation. Loading resulted in fewer excellent restorations in all three restorative techniques but not in a statistically significant level.

  14. Minor changes in serum levels of cytokines after removal of amalgam restorations.

    Science.gov (United States)

    Björkman, Lars; Brokstad, Karl A; Moen, Ketil; Jonsson, Roland

    2012-06-01

    Dental amalgam restorations release mercury and silver which is absorbed and distributed in the body. Animal studies have shown that both elements may interfere with the host by activation of the immune system in genetically susceptible strains at exposure levels relevant to those from dental amalgam restorations. The aim of this study was to test the hypothesis of no change over time in concentrations of a number of immune mediators in serum after removal of all dental amalgam restorations in patients with health complaints attributed to their amalgam restorations and compare with a healthy reference group. Twenty patients previously examined at a specialty unit for health complaints attributed to dental materials were included in a clinical trial and had all amalgam restorations replaced with other dental restorative materials. Serum samples were collected before amalgam removal and 3 and 12 months after the removal was finished. Twenty blood donors matched for age and gender were used as comparison group. A fluorescent bead-based (Luminex) immunoassay kit was used to measure cytokines, chemokines and growth factors in serum. At baseline, the patient group had slightly higher values for GM-CSF, IL-6, IL-2R, IFN-alpha, IL-7, and IL-12p40/p70 compared with the reference group. After amalgam removal a decrease towards the median value of the reference group was found for GM-CSF, IL-8, and IL-7. In conclusion, removal of all dental amalgam restorations and replacement with other dental restorative materials was associated with decreased concentrations of Th1-type proinflammatory markers in serum.

  15. 2-Local Amalgams for the Simple Groups GL(5, 2), M24 and He, Ⅱ

    Institute of Scientific and Technical Information of China (English)

    Wolfgang Lempken

    2003-01-01

    We elaborate on a method of G. Michler [6] to construct finite groups with a prescribed involution centralizer H using compatible pairs and amalgamation of H and another naturally arising 2-local subgroup. Modifying this approach we deal with the particular set-up leading to the simple groups GL(5, 2), M24 and He and characterize these groups as the universal completions of certain 2-local amalgams of rank 3.

  16. Preparation of High-purity Copper Xxide for Electroplating%电镀用高纯氧化铜的合成方法

    Institute of Scientific and Technical Information of China (English)

    闫静; 王学炜; 王宇

    2015-01-01

    Basic copper carbonate was prepared with copper nitrate and ammonium bicarbonate as raw materials. Then active copper oxide was prepared by basic copper carbonate after high-temperature roasting. The properties of the active copper oxide were characterized by X-ray diffraction (XRD), purity determination and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The purity of active copper oxide prepared by this method could reach more than 99.3%, higher than the universal national standard of analytical reagent. And impurity content was far superior to the universal national standard of analytical reagent. Hence it could meet the requirements of high-purity, low-impurity for electroplating.%以硝酸铜与碳酸氢铵为原料,制备碱式碳酸铜,再经过高温焙烧,合成活性氧化铜粉.用X射线衍射(XRD)、含量测定、电感耦合等离子体原子发射光谱(ICP-AES)等方法对所得活性氧化铜粉末进行了表征.本方法合成的氧化铜纯度能达到99.3%以上,高于目前市场上的分析纯试剂标准,其它金属杂质也远远优于分析纯标准,达到了电镀用氧化铜高纯度、低杂质的要求.

  17. Monopicolinate cross-bridged cyclam combining very fast complexation with very high stability and inertness of its copper(II) complex.

    Science.gov (United States)

    Lima, Luís M P; Halime, Zakaria; Marion, Ronan; Camus, Nathalie; Delgado, Rita; Platas-Iglesias, Carlos; Tripier, Raphaël

    2014-05-19

    The synthesis of a new cross-bridged 1,4,8,11-tetraazacyclotetradecane (cb-cyclam) derivative bearing a picolinate arm (Hcb-te1pa) was achieved by taking advantage of the proton sponge properties of the starting constrained macrocycle. The structure of the reinforced ligand as well as its acid-base properties and coordination properties with Cu(2+) and Zn(2+) was investigated. The X-ray structure of the free ligand showed a completely preorganized conformation that lead to very fast copper(II) complexation under mild conditions (instantaneous at pH 7.4) or even in acidic pH (3 min at pH 5) at room temperature and that demonstrated high thermodynamic stability, which was measured by potentiometry (at 25 °C and 0.10 M in KNO3). The results also revealed that the complex exists as a monopositive copper(II) species in the intermediate pH range. A comparative study highlighted the important selectivity for Cu(2+) over Zn(2+). The copper(II) complex was synthesized and investigated in solution using different spectroscopic techniques and DFT calculations. The kinetic inertness of the copper(II) complex in acidic medium was evaluated by spectrophotometry, revealing the very slow dissociation of the complex. The half-life of 96 days, in 5 M HClO4, and 465 min, in 5 M HCl at 25 °C, show the high kinetic stability of the copper(II) chelate compared to that of the corresponding complexes of other macrocyclic ligands. Additionally, cyclic voltammetry experiments underlined the perfect electrochemical inertness of the complex as well as the quasi-reversible Cu(2+)/Cu(+) redox system. The coordination geometry of the copper center in the complex was established in aqueous solution from UV-vis and EPR spectroscopies.

  18. High-Temperature Tribological and Self-Lubricating Behavior of Copper Oxide-Doped Y-TZP Composite Sliding Against Alumina

    NARCIS (Netherlands)

    Valefi, Mahdiar; de Rooij, Matthias B.; Schipper, Dirk J.; Winnubst, Aloysius J.A.

    2011-01-01

    The tribological behavior of 5 wt% copper oxide-doped tetragonal zirconia polycrystal composite has been investigated while it slides against an alumina counterface under high temperature conditions. The effects of load (1, 2.5, and 5 N) and velocity (0.05 and 0.1 m/s) on the wear mechanism have

  19. A highly active and reusable copper(I)-tren catalyst for the "click" 1,3-dipolar cycloaddition of azides and alkynes.

    Science.gov (United States)

    Candelon, Nicolas; Lastécouères, Dominique; Diallo, Abdou Khadri; Aranzaes, Jaime Ruiz; Astruc, Didier; Vincent, Jean-Marc

    2008-02-14

    The copper(I) complex [Cu(C18(6)tren)]Br 1 (C18(6)tren = tris(2-dioctadecylaminoethyl)amine) which exhibits a good stability towards aerobic conditions is a versatile, highly reactive and recyclable catalyst for the Huisgen cycloaddition of azides with terminal or internal alkynes and is a useful catalyst for the preparation of "click" dendrimers.

  20. Copper-Catalyzed [4 + 1] Annulation between α-Hydroxy Ketones and Nitriles: An Approach to Highly Substituted 3(2H)-Furanones.

    Science.gov (United States)

    He, Haitao; Qi, Chaorong; Hu, Xiaohan; Ouyang, Lu; Xiong, Wenfang; Jiang, Huanfeng

    2015-05-15

    A copper-catalyzed [4 + 1] annulation between α-hydroxy ketones and nitriles has been developed. The reaction provides a facile and efficient method for the construction of a wide range of highly substituted 3(2H)-furanones, a class of important compounds known to be associated with several biological activities.

  1. Jiangrun Copper Limited Company Set its Eyes on the Leading Position of Copper Processing Industry in China

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Jiangrun Copper Limited Company’s total investment volume for projects of stranded copper wire with high strength and high conductivity as well as high-performance copper and copper alloy wire are 500 million yuan and 360 million yuan, respectively. The company plans to introduce 85 units (sets) of high-end

  2. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin

    Directory of Open Access Journals (Sweden)

    Mahdi S

    2008-06-01

    Full Text Available Amalgam′s non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05 Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  3. Characterisation of baroque tin amalgam mirrors of the historical Green Vault in Dresden

    Science.gov (United States)

    Zywitzki, O.; Nedon, W.; Kopte, T.; Modes, T.

    2008-07-01

    The historical Green Vault, one of Europe’s most sumptuous treasure chambers, has reopened in September 2006 in the Dresden Royal Palace. For the baroque presentation of the artworks the special properties of tin amalgam mirrors are of great importance. A comprehensive analytic characterisation was necessary for restoration and reconstruction. The different original casting glasses were analysed in respect of chemical composition, roughness, waviness and optical properties like chromaticity coordinates and transmittance. The microstructure of the tin amalgam layers were investigated on metallographic cross-sections and by X-ray diffraction. The investigations reveal that the tin amalgam layers are composed of γ-HgSn6-10 phase with a grain size between 5 and 50 μm surrounded by a thin mercury phase with about 2 wt. % tin. However the most important property of the baroque tin amalgam mirrors is a relative low reflectivity of about 59% which is drastically lower than for silver mirrors with a reflectivity of about 96%. According to the characterisation results a suitable glass for reconstruction was selected. The mirror layers were produced by historical tin amalgam technology for the rooms not destroyed by bombarding of Dresden in February 1945. For the completely destroyed Jewel Room pure tin layers were deposited by magnetron sputtering. The results show that this new technology enables an adequate substitute for the original tin amalgam layers.

  4. Central centrifugal cicatricial alopecia amalgamated with alopecia areata: immunologic findings

    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu Velez

    2014-07-01

    Full Text Available Introduction: Both scarring and non-scarring alopecias exist; however, rare cases demonstrate features of both classes. Case Report: We describe an interesting alopecia case with amalgamated clinical, histologic and immunopathologic features of scarring and non-scarring alopecia. Specifically, the case displays combined features of alopecia areata (AA and of central centrifugal cicatricial alopecia (CCCA. A 36 year old female presented with symmetric, round, patchy hair loss on her scalp. Methods: Biopsies for hematoxylin and eosin (H&E examination, as well as for special stains, direct immunofluorescence (DIF and immunohistochemistry (IHC were performed. Results: The H&E biopsy revealed focally diminished hair follicular units, and sebaceous gland damage. Perifollicular concentric fibrosis was confirmed by Verhoeff elastin special staining. Antibodies to micelles were noted. Positive IHC staining for CD4, CD8, CD45 and multiple proteases and protease inhibitors was noted around selected follicular unit remnants. Conclusion: We present a rare alopecia, combining histologic features of CCCA with additional, selected immunologic features of AA.

  5. Reduction in operatory mercury levels after contamination or amalgam removal.

    Science.gov (United States)

    Ferracane, J L; Engle, J H; Okabe, T; Mitchem, J C

    1994-04-01

    The threshold limit value (TLV) for occupational exposure to mercury can be exceeded in the dental operatory after a contamination event or during certain dental procedures. The objective of this study was to determine the time required for the mercury vapor levels to return to baseline in both non-ventilated and ventilated operatories after they had been contaminated with mercury to the TLV of 0.050 mg/m3; and to evaluate the efficiency of an activated charcoal filtering device for removing mercury vapor. The results showed that even in a poorly ventilated operatory, the mercury vapor level returned to background within 20-30 minutes after a contamination, and within 10-20 minutes when the operatory was ventilated. The filtering device reduced the level of mercury vapor by approximately 25% during a continuous contamination event, but did not clear the operatory faster than normal settling after a limited source contamination. The filter caused a significant reduction in mercury in the breathing zones of the patient and dentist during and after amalgam removal, but did not eliminate the exposure. This study demonstrated the difficulty in contaminating an operatory with mercury vapor and confirmed the limited time mercury remains airborne, presumably due to its density and affinity for surfaces.

  6. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  7. Potentiometric stripping analysis of zinc and copper in human teeth and dental materials.

    Science.gov (United States)

    Kalicanin, Biljana M; Nikolić, Ruzica S

    2008-01-01

    Potentiometric stripping analysis (PSA) with oxygen as the oxidant has been used to determine soluble zinc and copper levels in exfoliated human teeth (all of which required extraction for orthodontic reasons) and commercial dental materials. The soluble zinc and copper contents of teeth were slightly below the zinc and copper contents in whole teeth reported by other researchers, except in the case of tooth with removed amalgam filling. Soluble zinc and copper concentrations of the dental materials and metal ceramic crowns were 0.50-6.30, and of 2.00-4.30 microg/g, respectively. The results of this work suggest that PSA may be a good method for zinc and copper leaching studies during the investigation of dental prosthetic materials' biocompatibility. Corrosive action of acidic media as evidenced by SEM micrographs caused the leaching of metal ions from teeth.

  8. Poor quality evidence suggests that failure rates for atraumatic restorative treatment and conventional amalgam are similar.

    Science.gov (United States)

    Hurst, Dominic

    2012-06-01

    The Medline, Cochrane CENTRAL, Biomed Central, Database of Open Access Journals (DOAJ), OpenJ-Gate, Bibliografia Brasileira de Odontologia (BBO), LILACS, IndMed, Sabinet, Scielo, Scirus (Medicine), OpenSIGLE and Google Scholar databases were searched. Hand searching was performed for journals not indexed in the databases. References of included trials were checked. Prospective clinical trials with test and control groups with a follow up of at least one year were included. Data abstraction was conducted independently and clinical and methodologically homogeneous data were pooled using a fixed-effects model. Eighteen trials were included. From these 32 individual dichotomous datasets were extracted and analysed. The majority of the results show no differences between both types of intervention. A high risk of selection-, performance-, detection- and attrition bias was identified. Existing research gaps are mainly due to lack of trials and small sample size. The current evidence indicates that the failure rate of high-viscosity GIC/ART restorations is not higher than, but similar to that of conventional amalgam fillings after periods longer than one year. These results are in line with the conclusions drawn during the original systematic review. There is a high risk that these results are affected by bias, and thus confirmation by further trials with suitably high numbers of participants is needed.

  9. Effects of Laser Pulse Heating of Copper Photocathodes on High-brightness Electron Beam Production at Blowout Regime

    CERN Document Server

    Zheng, Lianmin; Tang, Chuanxiang; Gai, Wei

    2016-01-01

    Producing high-brightness and high-charge (>100 pC) electron bunches at blowout regime requires ultrashort laser pulse with high fluence. The effects of laser pulse heating of the copper photocathode are analyzed in this paper. The electron and lattice temperature is calculated using an improved two-temperature model, and an extended Dowell-Schmerge model is employed to calculate the thermal emittance and quantum efficiency. A time-dependent growth of the thermal emittance and the quantum efficiency is observed. For a fixed amount of charge, the projected thermal emittance increases with the decreasing laser radius, and this effect should be taken into account in the laser optimization at blowout regime. Moreover, laser damage threshold fluence is simulated, showing that the maximum local fluence should be less than 40 mJ/cm^2 to prevent damage to the cathode. The cryogenic effect on the laser pulse heating is studied, showing that the hazards caused by the laser pulse heating will be significantly mitigated ...

  10. Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

    Directory of Open Access Journals (Sweden)

    Xin Wen Zhang

    2015-07-01

    Full Text Available Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.

  11. Enhancing the Wettability of High Aspect-Ratio Through-Silicon Vias Lined with LPCVD Silicon Nitride or PE-ALD Titanium Nitride for Void-Free Bottom-Up Copper Electroplating

    NARCIS (Netherlands)

    Saadaoui, M.; van Zeijl, H.; Wien, W. H. A.; Pham, H. T. M.; Kwakernaak, C.; Knoops, H. C. M.; Kessels, W. M. M.; R. van de Sanden,; Voogt, F. C.; Roozeboom, F.; Sarro, P. M.

    2011-01-01

    One of the critical steps toward producing void-free and uniform bottom-up copper electroplating in high aspect-ratio (AR) through-silicon vias (TSVs) is the ability of the copper electrolyte to spontaneously flow through the entire depth of the via. This can be accomplished by reducing the concentr

  12. Does intermunicipal cooperation create inefficiency? A comparison of interest rates paid by intermunicipal organizations, amalgamated municipalities and not recently amalgamated municipalities

    NARCIS (Netherlands)

    Allers, Maarten; van Ommeren, Bernard; Geertsema, Bieuwe

    2015-01-01

    In many countries, local governments operating on a small scale face a choice between amalgamation and cooperation. This paper applies a novel methodology to investigate the implications of this choice for operating efficiency. Using a unique micro-level dataset of over 11,000 loans made to both mun

  13. Highly stable copper oxide composite as an effective photocathode for water splitting via a facile electrochemical synthesis strategy

    KAUST Repository

    Zhang, Zhonghai

    2012-01-01

    Hydrogen generation through photoelectrochemical (PEC) water splitting using solar light as an energy resource is believed to be a clean and efficient way to overcome the global energy and environmental problems. Extensive research effort has been focused on n-type metal oxide semiconductors as photoanodes, whereas studies of p-type metal oxide semiconductors as photocathodes where hydrogen is generated are scarce. In this paper, highly efficient and stable copper oxide composite photocathode materials were successfully fabricated by a facile two-step electrochemical strategy, which consists of electrodeposition of a Cu film on an ITO glass substrate followed by anodization of the Cu film under a suitable current density and then calcination to form a Cu 2O/CuO composite. The synthesized Cu 2O/CuO composite was composed of a thin layer of Cu 2O with a thin film of CuO on its top as a protecting coating. The rational control of chemical composition and crystalline orientation of the composite materials was easily achieved by varying the electrochemical parameters, including electrodeposition potential and anodization current density, to achieve an enhanced PEC performance. The best photocathode material among all materials prepared was the Cu 2O/CuO composite with Cu 2O in (220) orientation, which showed a highly stable photocurrent of -1.54 mA cm -2 at a potential of 0 V vs reversible hydrogen electrode at a mild pH under illumination of AM 1.5G. This photocurrent density was more than 2 times that generated by the bare Cu 2O electrode (-0.65 mAcm -2) and the stability was considerably enhanced to 74.4% from 30.1% on the bare Cu 2O electrode. The results of this study showed that the top layer of CuO in the Cu 2O/CuO composite not only minimized the Cu 2O photocorrosion but also served as a recombination inhibitor for the photogenerated electrons and holes from Cu 2O, which collectively explained much enhanced stability and PEC activity of the Cu 2O/CuO composite

  14. Effect of Surface Polishing on Mercury Release from Dental Amalgam After Treatment 16% Carbamide Peroxide Gel

    Directory of Open Access Journals (Sweden)

    Z. Khamverdi

    2011-03-01

    Full Text Available Objectives: This study evaluated the effect of surface polishing on mercury release from dental amalgam after treatment with 16% carbamide peroxide gel.Materials and Methods: Ninety-six samples from two different amalgam brands were prepared in truncated cone-shaped PVC polymer molds with an external surface area of 195 mm². Half of the specimens were polished with green and red rubber, a brush and tin oxide paste at low speed. Samples were treated with 16% carbamide peroxide gel intubes containing 3 mL of carbamide peroxide gel and 0.1 mL of distilled water for 14 and 28 hours. Subsequently, carbamide peroxide gel on the sample surfaces was rinsed away with 7.0 mL of distilled water until the volume of each tube increased to 10 mL. Themercury level of each solution was measured using the VAV–440 mercury analyzer system.Considering the surface area of each amalgam disc, mercury amounts were calculated in μg ⁄mm². Data were analyzed using two-way ANOVA.Results: There were significant differences between the mean levels of mercury release from polished vs. unpolished amalgam surfaces after treatment with 16% carbamide peroxide.Increasing the storage time from 14 to 28 hours did not result in significant changes in the amount of mercury release. There was no significant interaction effect between amalgam surface polish and storage time statistically.Conclusion: Polished amalgam restorations release less mercury after treatment with carbamide peroxide bleaching gel in comparison with unpolished amalgam restorations.

  15. The effect of surface treatment and position of the dental restoration on amalgam corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Mortazavi, V. [Isfahan Univ. of Medical Sciences, Faculty of Dentistry, Isfahan (Iran, Islamic Republic of); Fathi, M.H. [Isfahan Univ. of Technology, Materials Engineering Dept., Isfahan (Iran, Islamic Republic of)

    2003-07-01

    The aim of this research was to evaluate the effect of surface treatment, clinical operations and the condition and position of the dental restoration on amalgam corrosion behavior. Commercial amalgam alloy namely Oralloy was selected. Twenty-one amalgam samples were prepared. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of three surface clinical procedures; carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the interproximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was laid on the internal mold surfaces and amalgam paste was compacted in the mold. Electrochemical potentiodynamic tests were performed at a temperature of 37{+-}1 {sup o}C in physiological solution in order to determine and compare the corrosion behavior of dental amalgam samples, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam (P<0.05). The polished group possesses the lowest and the carved group shows the highest corrosion current density. The carved group shows more corrosion resistance in compare with the sample near the matrix band as an index of the proximal surfaces of restorations. It was concluded that even a simple clinical operation could effect on dental amalgam corrosion resistance. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance because dentist could perform no clinical surface treatment. (author)

  16. Uptake and accumulation of mercury from dental amalgam in the common goldfish, Carassius auratus

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, C.J

    2003-03-01

    Exposure of fish to concentrations of dental amalgam typically found in waste discharge leads to mercury accumulation in tissues. - In this study, the bioavailability and accumulation of mercury from external environmental exposure to mixed, cured, milled, sieved and proportioned dental amalgam was examined in the common goldfish, Carassius auratus. Fish were exposed to dental amalgam (particle size range from <0.10 to 3.15 mm) in order to represent the particle size and distribution of that found within the typical dental office wastewater discharge stream. Experimental amalgam water loadings were 0 g/l, 0.5 g/l and 1 g/l in glass aquaria at 15 deg. C for 28 days. Fish tissues were sampled at 5 min and 28 days of exposure, and the liver, brain, muscle and whole body analyzed for total mercury using cold vapor atomic fluorescence spectroscopy. Mercury was found in several tissues examined and generally increased with exposure to higher amounts of dental amalgam. The highest levels were found in the whole body (17.68{+-}5.73 {mu}g/g) followed by the liver (0.80{+-}0.16 {mu}g/g) and muscle (0.47{+-}0.16 {mu}g/g). The lowest concentrations were seen in the brain (0.28{+-}0.19 {mu}g/g). Compared to controls, concentrations in the whole body, muscle and liver in fish exposed for 28 days to the highest concentration of amalgam were 200-, 233-, and 40-fold higher, respectively. This study shows that mercury from an environmental exposure to representative samples of dental amalgam typically found within the dental wastewater discharge stream is bioavailable to fish and may accumulate in internal tissues.

  17. Biotemplated synthesis of high specific surface area copper-doped hollow spherical titania and its photocatalytic research for degradating chlorotetracycline

    Science.gov (United States)

    Bu, Dan; Zhuang, Huisheng

    2013-01-01

    Copper-doped titania (Cu/TiO2) hollow microspheres were fabricated using the rape pollen as biotemplates via an improved sol-gel method and a followed calcinations process. In the fabricated process, a titanium(IV)-isopropoxide-based sol directly coated onto the surface of rape pollen. Subsequently, after calcinations, rape pollen was removed by high temperature and the hollow microsphere structure was retained. The average diameter of as-obtained hollow microspheres is 15-20 μm and the thickness of shell is approximately 0.6 μm. Knowing from XRD results, the main crystal phase of microspheres is anatase, coupled with rutile. The specific surface area varied between 141.80 m2/g and 172.51 m2/g. This hollow sphere photocatalysts with high specific surface area exhibited stronger absorption ability and higher photoactivity, stimulated by visible light. The degradation process of chlortetracycline (CTC) solution had been studied. The degradated results indicate that CTC could be effective degradated by fabricated hollow spherical materials. And the intermediate products formed in the photocatalytic process had been identified.

  18. Eta Production at High Transverse Momentum by Negative 520 GeV/c Pions Incident on Beryllium and Copper Targets

    Energy Technology Data Exchange (ETDEWEB)

    Roser, Robert Martin [Univ. of Rochester, NY (United States)

    1994-01-01

    This thesis presents a measurement of the production of high transverse momentum 17 mesons by a 520 GeV /c $\\sqrt{s}$ = 31.2) $\\pi^-$ beam using data collected during the 1990 fixed target run of Fermilab experiment E706. E706 is a second generation fixed target experiment designed to measure direct-photon production in hadron-nucleus collisions. These data provide a clean test of perturbative QCD and serve as a valuable tool for probing hadronic structure. The $\\gamma\\gamma$ decay mode of the $\\eta$ meson was studied using data from a highly segmented electromagnetic lead liquid argon sampling calorimeter. Results are presented for inclusive $\\eta$ production by $\\pi^-$ beams on both beryllium and copper targets. The $\\eta$ to $\\pi^0$ production ratio and the nuclear dependence of the $\\eta$ production cross section are also reported. These results are for $\\eta$'s in the transverse momentum range 3.5 to 9 Ge V / c and the center of mass rapidity range -0.75 to 0.75, and are the highest energy results ever obtained for inclusive $\\eta$ production using a $\\pi^-$ beam.

  19. Abundance, activity, and diversity of archaeal and bacterial communities in both uncontaminated and highly copper-contaminated marine sediments.

    Science.gov (United States)

    Besaury, Ludovic; Ghiglione, Jean-François; Quillet, Laurent

    2014-04-01

    We analyzed the impact of copper mine tailing discharges on benthic Archaea and Bacteria around the city of Chanaral in northern Chile. Quantitative PCR (Q-PCR) showed that the bacteria dominated the prokaryotic community at both sites, but only the bacteria showed a decrease in abundance in the copper-contaminated site. Q-PCR on reverse transcripts indicated a higher activity of both bacterial and archaeal communities in the contaminated site, suggesting an adaptation of the two communities to copper. This hypothesis was reinforced by the concomitant augmentation of the copper-resistant copA gene coding for a P-type ATP-ase pump in the contaminated site. The metabolically active bacterial community of the contaminated site was dominated by Gammaproteobacteria related to Ectothiorhodospiraceae and Chromatiaceae and by Alphaproteobacteria phylum related to Rhodobacteraceae. The metabolically active archaeal community was dominated by one lineage belonging to unclassified Euryarchaeota and to methanogenic Archaea.

  20. Quantitative evaluation of metal artifacts using different CBCT devices, high-density materials and field of views.

    Science.gov (United States)

    Codari, Marina; de Faria Vasconcelos, Karla; Ferreira Pinheiro Nicolielo, Laura; Haiter Neto, Francisco; Jacobs, Reinhilde

    2017-04-22

    To objectively compare the influence of different cone-beam computed tomography (CBCT) devices, high-density materials and field of views (FOVs) on metal artifact expression. For this in vitro study, three customized acrylic resin phantoms containing high-density materials cylinders: titanium, copper-aluminum alloy and amalgam were scanned on three CBCT devices using high-resolution protocols, same voxel size (0.2 mm) and different FOVs. After fully automatic segmentation and image registration, the same region of interest was defined for the small and medium FOVs. The difference between the segmented and the real volume of the metal cylinders was assessed. Moreover for each segmented slice, the area difference between the segmented and the real axial section was determined. The artifacts on the background were measured as normalizing standard deviation of voxel values in the vicinity of the cylinder, in three different distances. Considerable differences were observed in volume measurements for all CBCTs devices and materials for both FOV sizes (up to 67%). The slice per slice area analysis indicated higher artifacts at the edges of the metal cylinder. Within the materials, amalgam and titanium had, respectively, the worst and best artifact expression in all the CBCT devices. Standard deviation values varied differently between the three distances in each device. Our in vitro study showed that different CBCT devices, high-density materials and FOV should be considered while evaluating CBCT images. More carefully, diagnosis conclusions should be drawn in images containing amalgam and copper-aluminum alloy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.