WorldWideScience

Sample records for base metal

  1. Refractory metal based superalloys

    International Nuclear Information System (INIS)

    Alonso, Paula R.; Vicente, Eduardo E.; Rubiolo, Gerardo H.

    1999-01-01

    Refractory metals are looked as promising materials for primary circuits in fission reactors and even as fusion reactor components. Indeed, superalloys could be developed which take advantage of their high temperature properties together with the benefits of a two- phase (intermetallic compound-refractory metal matrix) coherent structure. In 1993, researchers of the Office National d'Etudes et de Recherches Aerospatiales of France reported the observation of such a coherent structure in the Ta-Ti-Zr-Al-Nb-Mo system although the exact composition is not reported. The intermetallic compound would be Ti 2 AlMo based. However, the formation of this compound and its possible coexistence with a disordered bcc phase in the ternary system Ti-Al-Mo is a controversial subject in the related literature. In this work we develop a technique to obtain homogeneous alloys samples with 50 Ti-25 Al-25 Mo composition. The resulting specimens were characterized by optical and electronic metallography (SEM), microprobe composition measurements (EPMA) and X-ray diffraction (XRD) analyses. The results show the evidence for a bcc (A2→B2) ordering reaction in the Ti-Al-Mo system in the 50 Ti-25 Al-25 Mo composition. (author)

  2. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  3. Metal-Based PSMA Radioligands

    Directory of Open Access Journals (Sweden)

    Eleni Gourni

    2017-03-01

    Full Text Available Prostate cancer is one of the most common malignancies for which great progress has been made in identifying appropriate molecular targets that would enable efficient in vivo targeting for imaging and therapy. The type II integral membrane protein, prostate specific membrane antigen (PSMA is overexpressed on prostate cancer cells in proportion to the stage and grade of the tumor progression, especially in androgen-independent, advanced and metastatic disease, rendering it a promising diagnostic and/or therapeutic target. From the perspective of nuclear medicine, PSMA-based radioligands may significantly impact the management of patients who suffer from prostate cancer. For that purpose, chelating-based PSMA-specific ligands have been labeled with various diagnostic and/or therapeutic radiometals for single-photon-emission tomography (SPECT, positron-emission-tomography (PET, radionuclide targeted therapy as well as intraoperative applications. This review focuses on the development and further applications of metal-based PSMA radioligands.

  4. Gold based bulk metallic glass

    Science.gov (United States)

    Schroers, Jan; Lohwongwatana, Boonrat; Johnson, William L.; Peker, Atakan

    2005-08-01

    Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5mm in the best glassformer. Au49Ag5.5Pd2.3Cu26.9Si16.3 has a liquidus temperature of 644K, a glass transition temperature of 401K, and a supercooled liquid region of 58K. The Vickers hardness of the alloys in this system is ˜350Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry.

  5. Speciation in Metal Toxicity and Metal-Based Therapeutics

    Directory of Open Access Journals (Sweden)

    Douglas M. Templeton

    2015-04-01

    Full Text Available Metallic elements, ions and compounds produce varying degrees of toxicity in organisms with which they come into contact. Metal speciation is critical to understanding these adverse effects; the adjectives “heavy” and “toxic” are not helpful in describing the biological properties of individual elements, but detailed chemical structures are. As a broad generalization, the metallic form of an element is inert, and the ionic salts are the species that show more significant bioavailability. Yet the salts and other chelates of a metal ion can give rise to quite different toxicities, as exemplified by a range of carcinogenic potential for various nickel species. Another important distinction comes when a metallic element is organified, increasing its lipophilicity and hence its ability to penetrate the blood brain barrier, as is seen, for example, with organic mercury and tin species. Some metallic elements, such as gold and platinum, are themselves useful therapeutic agents in some forms, while other species of the same element can be toxic, thus focusing attention on species interconversions in evaluating metal-based drugs. The therapeutic use of metal-chelating agents introduces new species of the target metal in vivo, and this can affect not only its desired detoxification, but also introduce a potential for further mechanisms of toxicity. Examples of therapeutic iron chelator species are discussed in this context, as well as the more recent aspects of development of chelation therapy for uranium exposure.

  6. Metallic Nanostructures Based on DNA Nanoshapes

    Directory of Open Access Journals (Sweden)

    Boxuan Shen

    2016-08-01

    Full Text Available Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable development of DNA-based nanostructures has provided many successful methods and realizations for these needs, such as chemical DNA metallization via seeding or ionization, as well as DNA-guided lithography and casting of metallic nanoparticles by DNA molds. These methods offer high resolution, versatility and throughput and could enable the fabrication of arbitrarily-shaped structures with a 10-nm feature size, thus bringing novel applications into view. In this review, we cover the evolution of DNA-based metallic nanostructures, starting from the metallized double-stranded DNA for electronics and progress to sophisticated plasmonic structures based on DNA origami objects.

  7. Metal detector technology data base

    Energy Technology Data Exchange (ETDEWEB)

    Porter, L.K.; Gallo, L.R.; Murray, D.W.

    1990-08-01

    The tests described in this report were conducted to obtain information on the effects target characteristics have on portal type metal detector response. A second purpose of the tests was to determine the effect of detector type and settings on the detection of the targets. Although in some cases comparison performance of different types and makes of metal detectors is found herein, that is not the primary purpose of the report. Further, because of the many variables that affect metal detector performance, the information presented can be used only in a general way. The results of these tests can show general trends in metal detection, but do little for making accurate predictions as to metal detector response to a target with a complex shape such as a handgun. The shape of an object and its specific metal content (both type and treatment) can have a significant influence on detection. Thus it should not be surprising that levels of detection for a small 100g stainless steel handgun are considerably different than for detection of the 100g stainless steel right circular cylinder that was used in these tests. 7 figs., 1 tab.

  8. Model Based Metal Transfer Control

    DEFF Research Database (Denmark)

    Thomsen, Jesper Sandberg

    2006-01-01

    In pulsed gas metal arc welding (pulsed GMAW) current pulses are used for detaching drops at the tip of the electrode. To obtain a high weld quality one drop should be detached for every pulse, and moreover, the amount of energy used for detachment should be kept at a minimum. Thus, each pulse mu...

  9. Thermodynamic data-base for metal fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

    2001-05-01

    This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project.

  10. Thermodynamic data-base for metal fluorides

    International Nuclear Information System (INIS)

    Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

    2001-05-01

    This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project

  11. Base Metal Co-Fired Multilayer Piezoelectrics

    Directory of Open Access Journals (Sweden)

    Lisheng Gao

    2016-03-01

    Full Text Available Piezoelectrics have been widely used in different kinds of applications, from the automobile industry to consumer electronics. The novel multilayer piezoelectrics, which are inspired by multilayer ceramic capacitors, not only minimize the size of the functional parts, but also maximize energy efficiency. Development of multilayer piezoelectric devices is at a significant crossroads on the way to achieving low costs, high efficiency, and excellent reliability. Concerning the costs of manufacturing multilayer piezoelectrics, the trend is to replace the costly noble metal internal electrodes with base metal materials. This paper discusses the materials development of metal co-firing and the progress of integrating current base metal chemistries. There are some significant considerations in metal co-firing multilayer piezoelectrics: retaining stoichiometry with volatile Pb and alkaline elements in ceramics, the selection of appropriate sintering agents to lower the sintering temperature with minimum impact on piezoelectric performance, and designing effective binder formulation for low pO2 burnout to prevent oxidation of Ni and Cu base metal.

  12. 21 CFR 872.3710 - Base metal alloy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that is...

  13. Ta-based amorphous metal thin films

    Energy Technology Data Exchange (ETDEWEB)

    McGlone, John M., E-mail: mcglone@eecs.oregonstate.edu [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-5501 (United States); Olsen, Kristopher R. [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Stickle, William F.; Abbott, James E.; Pugliese, Roberto A.; Long, Greg S. [Hewlett-Packard Company, Corvallis, OR, 97333 (United States); Keszler, Douglas A. [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Wager, John F. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-5501 (United States)

    2015-11-25

    With their lack of grains and grain boundaries, amorphous metals are known to possess advantageous mechanical properties and enhanced chemical stability relative to crystalline metals. Commonly, however, they exhibit poor high-temperature stability because of their metastable nature. Here, we describe two new Ta-based ternary metal thin films that retain thermal stability to 600 °C and above. The new thin-film compositions, Ta{sub 2}Ni{sub 2}Si{sub 1} and Ta{sub 2}Mo{sub 2}Si{sub 1}, are amorphous, exhibiting ultra-smooth surfaces (<0.4 nm) and resistivities typical of amorphous metals (224 and 177 μΩ cm, respectively). - Highlights: • New Ta-based amorphous metals were sputter deposited from individual targets. • As-deposited amorphous structure was confirmed through diffraction techniques. • Electrical and surface properties were characterized and possess smooth surfaces. • No evidence of crystallization up to 600 °C (TaNiSi) and 800 °C (TaMoSi). • Ultra-smooth surfaces remained unchanged up to crystallization temperature.

  14. Chemoelectronic circuits based on metal nanoparticles

    Science.gov (United States)

    Yan, Yong; Warren, Scott C.; Fuller, Patrick; Grzybowski, Bartosz A.

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the ‘jammed’ nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems ‘chemoelectronic’. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also ‘green’, in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

  15. Computational chemistry and metal-based radiopharmaceuticals

    International Nuclear Information System (INIS)

    Neves, M.; Fausto, R.

    1998-01-01

    Computer-assisted techniques have found extensive use in the design of organic pharmaceuticals but have not been widely applied on metal complexes, particularly on radiopharmaceuticals. Some examples of computer generated structures of complexes of In, Ga and Tc with N, S, O and P donor ligands are referred. Besides parameters directly related with molecular geometries, molecular properties of the predicted structures, as ionic charges or dipole moments, are considered to be related with biodistribution studies. The structure of a series of oxo neutral Tc-biguanide complexes are predicted by molecular mechanics calculations, and their interactions with water molecules or peptide chains correlated with experimental data of partition coefficients and percentage of human protein binding. The results stress the interest of using molecular modelling to predict molecular properties of metal-based radiopharmaceuticals, which can be successfully correlated with results of in vitro studies. (author)

  16. Base metal dehydrogenation of amine-boranes

    Science.gov (United States)

    Blacquiere, Johanna Marie [Ottawa, CA; Keaton, Richard Jeffrey [Pearland, TX; Baker, Ralph Thomas [Los Alamos, NM

    2009-06-09

    A method of dehydrogenating an amine-borane having the formula R.sup.1H.sub.2N--BH.sub.2R.sup.2 using base metal catalyst. The method generates hydrogen and produces at least one of a [R.sup.1HN--BHR.sup.2].sub.m oligomer and a [R.sup.1N--BR.sup.2].sub.n oligomer. The method of dehydrogenating amine-boranes may be used to generate H.sub.2 for portable power sources, such as, but not limited to, fuel cells.

  17. Effect of Metal Collar on Marginal Distortion of Base Metal Crowns

    Directory of Open Access Journals (Sweden)

    Grami Panah F

    2000-06-01

    Full Text Available It has been shown that noble alloys require metal collar to resist distortion when subjected to"nrepeat firing cycle of porcelain. Metal collar is undesirable due to esthetic concerns. Since base metal"nalloys have superior physical properties, it seems that metal collar would not be necessary for obtaining"nbetter marginal adaptation of base metal crowns. The Purpose of this study was to evaluate the effect of"nmetal collar on marginal distortion of base metal- ceramic crowns, Twenty base metal copings were"nconstructed and divided into two groups with and without collars. After surface preparation, porcelain"nwas applied onto the surface of specimens. Marginal gap was measured by scanning electron microscope"nduring three stages of crown fabrication: before degassing, after degassing and after glazing. The mean"nmeasurements in collarless group were; 21.4±13.4, 2I.4±14.9 and 21.9±11.9 u_m, respectively, and in-"ngroup with collar; 24.7±11.4, 24.0±! 1.5 and 26.6±11.7 urn, respectively. Two- way ANOVA revealed"nno significant difference in the mean values between two groups and among different stages of crown"nfabrication. The results of this study showed that base metal alloys did not distort during crown"nfabrication and metal collar had no effect on the amount of marginal opening (gap.

  18. Application of Fe-based metallic glasses in wastewater treatment

    International Nuclear Information System (INIS)

    Lin Bao; Bian Xiufang; Wang Pan; Luo Guanping

    2012-01-01

    Highlights: ► We found the Fe-based metallic glasses have potential application in wastewater treatment. ► The corrosion on the surface of Fe-based metallic glasses is related to the application. ► We set a new theory to explain the process of degredation organic metters with Fe-based metallic glasses. - Abstract: This work pioneered the use of the Fe 78 Si 9 B 13 metallic glass ribbons in wastewater treatment. Fe 78 Si 9 B 13 metallic glass was employed to remediate wastewater contaminated with a mixture of organic dyes. The removal rate of chemical oxygen demand (COD) with Fe 78 Si 9 B 13 metallic glass and metallic Fe 0 was up to 23 ± 0.93% in 30 min and 21 ± 0.67% with in 45 min, respectively. The dosage of Fe-based metallic glass was only 1/25 of that of metallic Fe 0 to obtain equivalent effects. The mechanism of wastewater treatment through Fe-based metallic glasses is discussed.

  19. Carbon-supported base metal nanoparticles : Cellulose at work

    NARCIS (Netherlands)

    Hoekstra, Jacco; Versluijs-Helder, Marjan; Vlietstra, Edward J.; Geus, John W.; Jenneskens, Leonardus W.

    2015-01-01

    Pyrolysis of base metal salt loaded microcrystalline cellulose spheres gives a facile access to carbon-supported base metal nanoparticles, which have been characterized with temperature-dependent XRD, SEM, TEM, ICP-MS and elemental analysis. The role of cellulose is multifaceted: 1) it facilitates a

  20. Development of metal based thermal barrier coatings

    Science.gov (United States)

    Shin, Dong-Il

    In this work, metal-based thermal barrier coatings (MBTBCs) have been produced, using high frequency induction plasma spraying (IPS) of iron-based nanostructured alloy powders. Important advances have been made over recent years to the development of ceramic-based thermal barrier coatings (TBCs) for internal combustion engines application, but they are not yet applied in mass production situations. Besides the important economic considerations, the reliability of ceramic: TBCs is also an issue, being associated with the difficulty of predicting their "in-service" lifetime. Through engineering of the nano/amorphous structure of MBTBCs, their thermal conductivity can be made as low as those of ceramic-based TBCs, with reduced mean free paths of the electrons/phonons scattering. In this work, nano/amorphous structured coatings were deposited by IPS using the following spray parameters: spraying distance (210 ˜ 270 mm), plasma gas composition (Ar/N2), IPS torch power (24kW), and powder feed-rate (16g/min.). The structure and properties of the deposited layers were characterized through SEM (Scanning Electron Microscopy) observations. The thermal diffusivity (alpha) properties of the MBTBCs were measured using a laser flash method. Density (rho) and specific heat (Cp) of the MBTBCs were also measured, and their thermal conductivity (k) calculated (k =alpharhoCp). The thermal conductivity of MBTBCs was found to be as low as 1.99 W/m/K. The heat treatment study showed that crystal structure changes, and grain size growth from a few nanometers to tenth of nanometers occurred at 550°C under static exposure conditions. Thermal expansion coefficient (TEC) of MBTBCs was 13E-6/K, which is close to the TEC of cast iron and thus, closer to the TEC values of aluminium alloys than are conventional TBCs. Fracture toughness of MBTBCs has also been assessed by use of Vickers hardness tests, with a 500 g load for 15 s, and the results show that there are no measurable crack

  1. Plasmonic modulator based on gain-assisted metal-semiconductor-metal waveguide

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia E.; Kulkova, Irina V.; Malureanu, Radu

    2012-01-01

    We investigate plasmonic modulators with a gain material to be implemented as ultra-compact and ultra-fast active nanodevices in photonic integrated circuits. We analyze metal-semiconductor-metal (MSM) waveguides with InGaAsP-based active material layers as ultra-compact plasmonic modulators. The...

  2. Surface/structure functionalization of copper-based catalysts by metal-support and/or metal-metal interactions

    Science.gov (United States)

    Konsolakis, Michalis; Ioakeimidis, Zisis

    2014-11-01

    Cu-based catalysts have recently attracted great attention both in catalysis and electro-catalysis fields due to their excellent catalytic performance and low cost. Given that their performance is determined, to a great extent, by Cu sites local environment, considerable efforts have been devoted on the strategic modifications of the electronic and structural properties of Cu sites. In this regard, the feasibility of tuning the local structure of Cu entities by means of metal-support or metal-metal interactions is investigated. More specifically, the physicochemical properties of Cu entities are modified by employing: (i) different oxides (CeO2, La2O3, Sm2O3), or (ii) ceria-based mixed oxides (Ce1-xSmxOδ) as supporting carriers, and (iii) a second metal (Cobalt) adjacent to Cu (bimetallic Cu-Co/CeO2). A characterization study, involving BET, XRD, TPR, and XPS, reveal that significant modifications on structural, redox and electronic properties of Cu sites can be induced by adopting either different oxide carriers or bimetallic complexes. Fundamental insights into the tuning of Cu local environment by metal-support or metal-metal interactions are provided, paving the way for real-life industrial applications.

  3. Saccharide-based Approach to Green Metallic Nanostructure Synthesis

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Sørensen, Karsten Holm; Jensen, Palle Skovhus

    A green approach to solution synthesis of metallic nanoparticles has been developed using harmless and bioapplicable chemicals as well as moderate temperatures. Metal precursors are reduced by glucose/buffers and sterically stabilized by starch. The saccharide based procedure is highly diverse...

  4. Liquid metal actuation-based reversible frequency tunable monopole antenna

    Science.gov (United States)

    Kim, Daeyoung; Pierce, Richard G.; Henderson, Rashaunda; Doo, Seok Joo; Yoo, Koangki; Lee, Jeong-Bong

    2014-12-01

    We report the fabrication and characterization of a reversible resonant frequency tunable antenna based on liquid metal actuation. The antenna is composed of a coplanar waveguide fed monopole stub printed on a copper-clad substrate, and a tunnel-shaped microfluidic channel linked to the printed metal. The gallium-based liquid metal can be injected and withdrawn from the channel in response to an applied air pressure. The gallium-based liquid metal is treated with hydrochloric acid to eliminate the oxide layer, and associated wetting/sticking problems, that arise from exposure to an ambient air environment. Elimination of the oxide layer allows for reliable actuation and repeatable and reversible tuning. By controlling the liquid metal slug on-demand with air pressure, the liquid metal can be readily controllable to connect/disconnect to the monopole antenna so that the physical length of the antenna reversibly tunes. The corresponding reversible resonant frequency changes from 4.9 GHz to 1.1 GHz. The antenna properties based on the liquid metal actuation were characterized by measuring the reflection coefficient and agreed well with simulation results. Additionally, the corresponding time-lapse images of controlling liquid metal in the channel were studied.

  5. SILANE-BASED CONVERSION COATING FOR METALS

    Science.gov (United States)

    For the past three years, a project to develop new pretreatment rinses for metals was carried out by the U.S. Environmental Protection Agency and the University of Cincinnati. The project involved optimization of laboratory rinses with dilute aqueous solutions organofunctional s...

  6. A Gallium-Based Magnetocaloric Liquid Metal Ferrofluid.

    Science.gov (United States)

    A de Castro, Isabela; Chrimes, Adam F; Zavabeti, Ali; Berean, Kyle J; Carey, Benjamin J; Zhuang, Jincheng; Du, Yi; Dou, Shi X; Suzuki, Kiyonori; Shanks, Robert A; Nixon-Luke, Reece; Bryant, Gary; Khoshmanesh, Khashayar; Kalantar-Zadeh, Kourosh; Daeneke, Torben

    2017-12-13

    We demonstrate a magnetocaloric ferrofluid based on a gadolinium saturated liquid metal matrix, using a gallium-based liquid metal alloy as the solvent and suspension medium. The material is liquid at room temperature, while exhibiting spontaneous magnetization and a large magnetocaloric effect. The magnetic properties were attributed to the formation of gadolinium nanoparticles suspended within the liquid gallium alloy, which acts as a reaction solvent during the nanoparticle synthesis. High nanoparticle weight fractions exceeding 2% could be suspended within the liquid metal matrix. The liquid metal ferrofluid shows promise for magnetocaloric cooling due to its high thermal conductivity and its liquid nature. Magnetic and thermoanalytic characterizations reveal that the developed material remains liquid within the temperature window required for domestic refrigeration purposes, which enables future fluidic magnetocaloric devices. Additionally, the observed formation of nanometer-sized metallic particles within the supersaturated liquid metal solution has general implications for chemical synthesis and provides a new synthetic pathway toward metallic nanoparticles based on highly reactive rare earth metals.

  7. Dual-energy-based metal segmentation for metal artifact reduction in dental computed tomography.

    Science.gov (United States)

    Hegazy, Mohamed A A; Eldib, Mohamed Elsayed; Hernandez, Daniel; Cho, Myung Hye; Cho, Min Hyoung; Lee, Soo Yeol

    2018-02-01

    In a dental CT scan, the presence of dental fillings or dental implants generates severe metal artifacts that often compromise readability of the CT images. Many metal artifact reduction (MAR) techniques have been introduced, but dental CT scans still suffer from severe metal artifacts particularly when multiple dental fillings or implants exist around the region of interest. The high attenuation coefficient of teeth often causes erroneous metal segmentation, compromising the MAR performance. We propose a metal segmentation method for a dental CT that is based on dual-energy imaging with a narrow energy gap. Unlike a conventional dual-energy CT, we acquire two projection data sets at two close tube voltages (80 and 90 kV p ), and then, we compute the difference image between the two projection images with an optimized weighting factor so as to maximize the contrast of the metal regions. We reconstruct CT images from the weighted difference image to identify the metal region with global thresholding. We forward project the identified metal region to designate metal trace on the projection image. We substitute the pixel values on the metal trace with the ones computed by the region filling method. The region filling in the metal trace removes high-intensity data made by the metallic objects from the projection image. We reconstruct final CT images from the region-filled projection image with the fusion-based approach. We have done imaging experiments on a dental phantom and a human skull phantom using a lab-built micro-CT and a commercial dental CT system. We have corrected the projection images of a dental phantom and a human skull phantom using the single-energy and dual-energy-based metal segmentation methods. The single-energy-based method often failed in correcting the metal artifacts on the slices on which tooth enamel exists. The dual-energy-based method showed better MAR performances in all cases regardless of the presence of tooth enamel on the slice of

  8. CARBON-CONTAINING COMPOSITES BASED ON METALS

    Directory of Open Access Journals (Sweden)

    VAGANOV V. E.

    2015-10-01

    Full Text Available Problem statement Among the developed technologies metal-composites production,a special place takes powder metallurgy, having fundamental differences from conventionally used foundry technologies. The main advantages of this technology are: the possibility of sensitive control, the structure and phase composition of the starting components, and ultimately the possibility of obtaining of bulk material in nanostructured state with a minimum of processing steps. The potential reinforcers metals include micro and nano-sized oxides, carbides, nitrides, whiskers. The special position is occupied with carbon nanostructures (CNS: С60 fullerenes, single-layer and multi-layer nanotubes, onions (spherical "bulbs", nano-diamonds and graphite,their properties are being intensively studied in recent years. These objects have a high thermal and electrical conductivity values, superelasticity, and have a strength approximate to the theoretical value, which can provide an obtaining composite nanomaterial with a unique set of physical and mechanical properties. In creation of a metal matrix composite nanomaterials (CM, reinforced by various CNS, a special attention should be given to mechanical activation processes (MA already at the stage of preparation of the starting components affecting the structure, phase composition and properties of aluminum-matrix composites. Purpose. To investigate the influence of mechanical activation on the structure and phase composition of aluminum-matrix composites. Conclusion. The results of the study of the structure and phase composition of the initial and mechanically activated powders and bulk-modified metal-composites are shown, depending on the type and concentration of modifying varieties CNS, regimes of MA and parameters of compaction. The study is conducted of tribological properties of Al-CNS OF nanostructured materials.

  9. [Exposure to vegetal esters based metal cutting fluids: health effects].

    Science.gov (United States)

    Riva, M M; Bellini, M; Leghissa, P; Gambini, D; Mosconi, G

    2012-01-01

    The aim of our research is to study respiratory and dermatologic diseases (irritative and allergic) in a cohort of workers exposed to vegetal esters based metal cutting fluids of the latest generation. A cohort of 81 workers (mean age 34.5 years, seniority 17.4 years), with mean exposure to vegetal esters based metal cutting fluids of 2.8 years, has been subjected to clinical evaluations. The investigation did not reveal any disease or disorder of the respiratory system, any folluculitis or any allergic contact dermatitis caused by sensitization to vegetal esters based metal cutting fluids. On the contrary we documented 5 cases of irritant contact dermatitis, even if favored by an improper use of protection devices. According to early results, the introduction of vegetal esters based metal cutting fluids seems to reduce the risk to the worker's health. A longitudinal surveillance is still needed to confirm that even in the medium and long-term sensitizations will not occur.

  10. Exploration of the catalytic use of alkali metal bases

    OpenAIRE

    Bao, Wei

    2017-01-01

    This PhD thesis project was concerned with the use of alkali metal amide Brønsted bases and alkali metal alkoxide Lewis bases in (asymmetric) catalysis. The first chapter deals with formal allylic C(sp3)–H bond activation of aromatic and functionalized alkenes for subsequent C–C and C–H bond formations. The second chapter is focused on C(sp3)–Si bond activation of fluorinated pro-nucleophiles in view of C–C bond formations. In the first chapter, a screening of various metal amides...

  11. A new kind of metal detector based on chaotic oscillator

    Science.gov (United States)

    Hu, Wenjing

    2017-12-01

    The sensitivity of a metal detector greatly depends on the identification ability to weak signals from the probe. In order to improve the sensitivity of metal detectors, this paper applies the Duffing chaotic oscillator to metal detectors based on its characteristic which is very sensitive to weak periodic signals. To make a suitable Duffing system for detectors, this paper computes two Lyapunov characteristics exponents of the Duffing oscillator, which help to obtain the threshold of the Duffing system in the critical state accurately and give quantitative criteria for chaos. Meanwhile, a corresponding simulation model of the chaotic oscillator is made by the Simulink tool box of Matlab. Simulation results shows that Duffing oscillator is very sensitive to sinusoidal signals in high frequency cases. And experimental results show that the measurable diameter of metal particles is about 1.5mm. It indicates that this new method can feasibly and effectively improve the metal detector sensitivity.

  12. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  13. Heavy Metal Uptake by Novel Miscanthus Seed-Based Hybrids Cultivated in Heavy Metal Contaminated Soil

    Directory of Open Access Journals (Sweden)

    Krzyżak Jacek

    2017-09-01

    Full Text Available When heavy metal contaminated soils are excluded from food production, biomass crops offer an alternative commercial opportunity. Perennial crops have potential for phytoremediation. Whilst the conditions at heavy metal contaminated sites are challenging, successful phytoremediation would bring significant economic and social benefits. Seed-based Miscanthus hybrids were tested alongside the commercial clone Miscanthus × giganteus on arable land, contaminated with Pb, Cd and Zn near Katowice. Before the randomized experimental plots were established (25m2 plots with plant density 2/m2 ‘time-zero’ soil samples were taken to determine initial levels of total (aqua regia and bioavailable (CaCl2 extraction concentration of Pb, Cd and Zn. After the growing season plant material was sampled during autumn (October, green harvest and winter (March, brown harvest to determine differences in heavy metal uptake. Results after the first growing season are presented, including the plot establishment success, biomass yield and heavy metal uptake.

  14. Tunable, omnidirectional structural color on reflection based on metal-SiOx-metal structure

    Science.gov (United States)

    Yang, Chenying; Mao, Kening; Shen, Weidong; Fang, Bo; Fang, Xu; Zhang, Xing; Zhang, Yueguang; Liu, Xu

    2016-12-01

    An omnidirectional structural color based on the metal-SiOx-metal stack structure is proposed, which can present the same perceived color for a broad range of incidence angles. The tunable structural color can be obtained with adjustable intermediate dielectric layer by simply adjusting the deposition condition, especially the oxygen flow rate during the deposition processes. The resonance condition can be satisfied across the whole visible light region with this special dielectric. The strong absorption caused by the resonance within the metal-SiOx-metal structure accounts for the efficient spectral filtering feature, and the constant phase shift within the dielectric layer leads to angle insensitivity of this color filter. This simple color tuning method for omnidirectional structural colors can have a great potential in various applications such as displaying, imaging, colorful decoration, anti-counterfeiting and so forth.

  15. Structure and properties of transition metal-metalloid glasses based on refractory metals

    International Nuclear Information System (INIS)

    Johnson, W.L.; Williams, A.R.

    1979-01-01

    The structure and properties of several new transition metal-metalloid (TM/sub 1-x/M/sub x/) metallic glasses based on refractory transition metals (e.g. Mo, W, Ru etc.) have been systemically investigated as a function of composition. The structure of the alloys has been investigated by x-ray diffraction methods and measurements of superconducting properties, electrical resistivity, density, hardness, and mechanical behavior were made. These data are used in developing a novel description of the structure of TM/sub 1-x/M/sub x/ glasses. The experimental evidence suggests that an ideal amorphous phase forms at a specific composition x/sub c/ and that this phase has a well defined atomic short range order. For metallic glasses having x x/sub c/. This novel picture can explain the variation of many properties of these glasses with metalloid concentration

  16. Heavy Metal Uptake by Novel Miscanthus Seed-Based Hybrids Cultivated in Heavy Metal Contaminated Soil

    Science.gov (United States)

    Krzyżak, Jacek; Pogrzeba, Marta; Rusinowski, Szymon; Clifton-Brown, John; McCalmont, Jon Paul; Kiesel, Andreas; Mangold, Anja; Mos, Michal

    2017-09-01

    When heavy metal contaminated soils are excluded from food production, biomass crops offer an alternative commercial opportunity. Perennial crops have potential for phytoremediation. Whilst the conditions at heavy metal contaminated sites are challenging, successful phytoremediation would bring significant economic and social benefits. Seed-based Miscanthus hybrids were tested alongside the commercial clone Miscanthus × giganteus on arable land, contaminated with Pb, Cd and Zn near Katowice. Before the randomized experimental plots were established (25m2 plots with plant density 2/m2) `time-zero' soil samples were taken to determine initial levels of total (aqua regia) and bioavailable (CaCl2 extraction) concentration of Pb, Cd and Zn. After the growing season plant material was sampled during autumn (October, green harvest) and winter (March, brown harvest) to determine differences in heavy metal uptake. Results after the first growing season are presented, including the plot establishment success, biomass yield and heavy metal uptake.

  17. Chitosan-based Schiff base-metal complexes (Mn, Cu, Co) as ...

    Indian Academy of Sciences (India)

    based Schiff base-metal complexes (Mn, Cu, Co) as heterogeneous, new catalysts for the -isophorone oxidation. C S Thatte ... A new chitosan-based Schiff base was prepared and complexed with manganese, cobalt and copper. These Schiff ...

  18. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P. [A.V. Topchiev Institute of Petrochemical Synthesis RAS, Leninskiy Prospekt 29, 119991 Moscow Russia (Russian Federation)

    2016-05-18

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  19. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    International Nuclear Information System (INIS)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P.

    2016-01-01

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  20. Polyamorphism in Yb-based metallic glass induced by pressure

    Science.gov (United States)

    Li, Liangliang; Luo, Qiang; Li, Renfeng; Zhao, Haiyan; Chapman, Karena W.; Chupas, Peter J.; Wang, Luhong; Liu, Haozhe

    2017-04-01

    The Yb62.5Zn15Mg17.5Cu5 metallic glass is investigated using synchrotron x-ray total scattering method up to 38.4 GPa. The polyamorphic transformation from low density to high density with a transition region between 14.1 and 25.2 GPa is observed, accompanying with a volume collapse reflected by a discontinuousness of isothermal bulk modulus. This collapse is caused by that distortional icosahedron short range order precedes to perfect icosahedron, which might link to Yb 4f electron delocalization upon compression, and match the result of in situ electrical resistance measurement under high pressure conditions. This discovery in Yb-based metallic glass, combined with the previous reports on other metallic glass systems, demonstrates that pressure induced polyamorphism is the general behavior for typical lanthanide based metallic glasses.

  1. A new Mannich base and its transition metal (II) complexes ...

    Indian Academy of Sciences (India)

    Unknown

    some metal complexes of this type of Mannich base and investigate its bonding characteristics. We herein report a new Mannich base, N-(1-morpholinoben- zyl) semicarbazide formed by the three-component condensation, containing active hydrogen on nitro- gen (morpholine), benzaldehyde and semicarbazide.

  2. Indicator minerals as guides to base metal sulphide mineralisation ...

    Indian Academy of Sciences (India)

    and metamorphosed volcanogenic base metal sul- phide mineralisation, and based on compositional considerations, zincian spinel has been proposed as an indicator mineral and a potential exploration guide in the search of ores of this type (Sandhaus and Craig 1986; Sheridan and Raymond 1984; Spry and Scott 1986a ...

  3. Metal hydride-based thermal energy storage systems

    Science.gov (United States)

    Vajo, John J.; Fang, Zhigang

    2017-10-03

    The invention provides a thermal energy storage system comprising a metal-containing first material with a thermal energy storage density of about 1300 kJ/kg to about 2200 kJ/kg based on hydrogenation; a metal-containing second material with a thermal energy storage density of about 200 kJ/kg to about 1000 kJ/kg based on hydrogenation; and a hydrogen conduit for reversibly transporting hydrogen between the first material and the second material. At a temperature of 20.degree. C. and in 1 hour, at least 90% of the metal is converted to the hydride. At a temperature of 0.degree. C. and in 1 hour, at least 90% of the metal hydride is converted to the metal and hydrogen. The disclosed metal hydride materials have a combination of thermodynamic energy storage densities and kinetic power capabilities that previously have not been demonstrated. This performance enables practical use of thermal energy storage systems for electric vehicle heating and cooling.

  4. U-based metallic glasses with superior glass forming ability

    Science.gov (United States)

    Xu, Hongyang; Ke, Haibo; Huang, Huogen; Zhang, Pengguo; Pu, Zhen; Zhang, Pei; Liu, Tianwei

    2018-02-01

    By using Al as the third and B as the fourth but minor alloying elements for the U66.7Co33.3 basic metallic glass, a series of U-Co-Al(-B) alloys were designed. The quaternary U-Co-Al-B alloys exhibit significantly improved glass-forming ability (GFA) than previously reported U-based metallic glasses. Low fragility (∼24) is found for these new U-based metallic glasses. The improvement in GFA would result from denser atomic packing in the undercooled liquids due to the presence of small B atoms. Some U-Co-Al(-B) glasses showed corrosion resistance comparable to that of U64Co34Al2 glass, known for premium anti-corrosive performance among the unveiled U-based glasses.

  5. Base metal alloys used for dental restorations and implants.

    Science.gov (United States)

    Roach, Michael

    2007-07-01

    One of the primary reasons for the development of base metal alloys for dental applications has been the escalating cost of gold throughout the 20th century. In addition to providing lower cost alternatives, these nonprecious alloys were also found to provide better mechanical properties and aesthetics for some oral applications. Additionally, certain base metal alloy systems are preferred because of their superior mechanical properties, lower density, and in some cases, their capability to osseo-integrate. The base metal alloy systems most commonly used in dentistry today include stainless steels, nickel-chromium, cobalt-chromium, titanium, and nickel-titanium alloys. Combined, these alloy systems provide a wide range of available properties to choose the correct material for both temporary and long-term restoration and implant applications.

  6. Biomaterial based novel polyurethane adhesives for wood to wood and metal to metal bonding

    Directory of Open Access Journals (Sweden)

    Mitesh Ramanlal Patel

    2009-01-01

    Full Text Available Polyurethane adhesives made from synthetic chemicals are non-biodegradable, costly and difficult to find raw materials from local market. To avoid solid pollution problem, cost effectiveness and easy availability of raw materials, biomaterials based polyurethane adhesives are used in current industrial interest. Direct use of castor oil in polyurethane adhesive gives limited hardness. Modification on active sites of castor oil to utilize double bond of unsaturated fatty acid and carboxyl group yields new modified or activated polyols, which can be utilized for polyurethane adhesive formulation. In view of this, we have synthesized polyurethane adhesives from polyester polyols, castor oil based polyols and epoxy based polyols with Isocyanate adducts based on castor oil and trimethylolpropane. To study the effects of polyurethane adhesive strength (i.e. lap shear strength on wood-to-wood and metal-to-metal bonding through various types of polyols, cross-linking density, isocyanate adducts and also to compare adhesive strength between wood to wood and metal to metal surface. These polyols and polyurethanes were characterized through GPC, NMR and IR-spectroscopy, gel and surface drying time. Thermal stability of PU adhesives was determined under the effect of cross-linking density (NCO/OH ratio. The NCO/OH ratio (1.5 was optimized for adhesives as the higher NCO/OH ratio (2.0 increasing cross-linking density and decreases adhesion. Lower NCO/OH ratio (1.0 provideslow cross-linking density and low strength of adhesives.

  7. Plasmonic modulator based on thin metal-semiconductor-metal waveguide with gain core

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Malureanu, Radu; Lavrinenko, Andrei

    2013-01-01

    We focus on plasmonic modulators with a gain core to be implemented as active nanodevices in photonic integrated circuits. In particular, we analyze metal–semiconductor–metal (MSM) waveguides with InGaAsP-based active material layers. A MSM waveguide enables high field localization and therefore...

  8. Metal speciation in Dutch soils: Field-based partition coefficients for heavy metals at background levels

    NARCIS (Netherlands)

    Hoop MAGT van den; LAC

    1995-01-01

    For 13 Dutch soil samples, total concentrations in the solid phase and in the soil solution were determined for the heavy metals Cd, Cu, Ni, Pb and Zn. The soils were characterized in terms of organic carbon content, pH, clay content and cation exchange capacity. Average field-based

  9. Antimicrobial resistance challenged with metal-based antimicrobial macromolecules.

    Science.gov (United States)

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola

    2017-02-01

    Antimicrobial resistance threatens the achievements of science and medicine, as it deactivates conventional antimicrobial therapeutics. Scientists respond to the threat by developing new antimicrobial platforms to prevent and treat infections from these resistant strains. Metal-based antimicrobial macromolecules are emerging as an alternative to conventional platforms because they combine multiple mechanisms of action into one platform due to the distinctive properties of metals. For example, metals interact with intracellular proteins and enzymes, and catalyse various intracellular processes. The macromolecular architecture offers a means to enhance antimicrobial activity since several antimicrobial moieties can be conjugated to the scaffold. Further, these macromolecules can be fabricated into antimicrobial materials for contact-killing medical implants, fabrics, and devices. As volatilization or leaching out of the antimicrobial moieties from the macromolecular scaffold is reduced, these medical implants, fabrics, and devices can retain their antimicrobial activity over an extended period. Recent advances demonstrate the potential of metal-based antimicrobial macromolecules as effective platforms that prevent and treat infections from resistant strains. In this review these advances are thoroughly discussed within the context of examples of metal-based antimicrobial macromolecules, their mechanisms of action and biocompatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Charge transport in metal oxide nanocrystal-based materials

    Science.gov (United States)

    Runnerstrom, Evan Lars

    There is probably no class of materials more varied, more widely used, or more ubiquitous than metal oxides. Depending on their composition, metal oxides can exhibit almost any number of properties. Of particular interest are the ways in which charge is transported in metal oxides: devices such as displays, touch screens, and smart windows rely on the ability of certain metal oxides to conduct electricity while maintaining visible transparency. Smart windows, fuel cells, and other electrochemical devices additionally rely on efficient transport of ionic charge in and around metal oxides. Colloidal synthesis has enabled metal oxide nanocrystals to emerge as a relatively new but highly tunable class of materials. Certain metal oxide nanocrystals, particularly highly doped metal oxides, have been enjoying rapid development in the last decade. As in myriad other materials systems, structure dictates the properties of metal oxide nanocrystals, but a full understanding of how nanocrystal synthesis, the processing of nanocrystal-based materials, and the structure of nanocrystals relate to the resulting properties of nanocrystal-based materials is still nascent. Gaining a fundamental understanding of and control over these structure-property relationships is crucial to developing a holistic understanding of metal oxide nanocrystals. The unique ability to tune metal oxide nanocrystals by changing composition through the introduction of dopants or by changing size and shape affords a way to study the interplay between structure, processing, and properties. This overall goal of this work is to chemically synthesize colloidal metal oxide nanocrystals, process them into useful materials, characterize charge transport in materials based on colloidal metal oxide nanocrystals, and develop ways to manipulate charge transport. In particular, this dissertation characterizes how the charge transport properties of metal oxide nanocrystal-based materials depend on their processing and

  11. Theoretical analysis of a nanoscale plasmonic filter based on a rectangular metal-insulator-metal waveguide

    International Nuclear Information System (INIS)

    Yun Binfeng; Hu Guohua; Cui Yiping

    2010-01-01

    A compact and nanometric surface plasmon polariton (SPP) band-pass filter based on a rectangular ring resonator composed of metal-insulator-metal waveguides is proposed. Using the finite difference time domain method, the effects of the structure parameters on the transmission characteristics of this SPP band-pass filter are analysed in detail. The results show that the proposed SPP filter has narrow transmission peaks and the corresponding resonance wavelengths can be linearly tuned by altering the resonator's cavity length. Moreover, the transmission ratios of the pass bands can be tuned by changing the coupling gaps between the input/output MIM waveguides and the resonator. Also the metal loss and dispersion effects on the filter responses are included. The simple band-pass SPP filter is very promising for high-density SPP waveguide integrations.

  12. DFT study on metal-mediated uracil base pair complexes

    Directory of Open Access Journals (Sweden)

    Ayhan Üngördü

    2017-11-01

    Full Text Available The most stable of metal-mediated uracil base pair complexes were determined. Method was used density functional theory, B3LYP. The calculations of systems containing C, H, N, O were described by 6-311++G(d,p and cc-PVTZ basis sets and LANL2DZ and SDD basis sets was used for transition metals. Then Egap values of complexes were calculated and the electrical conductivity of the complexes for single nanowires was studied by band theory. Metal-mediated uracil base pair complexes which will be used as conductive wires in nanotechnology were predicted. In nanoworld, this study is expected to show a way for practical applications.

  13. A transparent electrode based on a metal nanotrough network.

    Science.gov (United States)

    Wu, Hui; Kong, Desheng; Ruan, Zhichao; Hsu, Po-Chun; Wang, Shuang; Yu, Zongfu; Carney, Thomas J; Hu, Liangbing; Fan, Shanhui; Cui, Yi

    2013-06-01

    Transparent conducting electrodes are essential components for numerous flexible optoelectronic devices, including touch screens and interactive electronics. Thin films of indium tin oxide-the prototypical transparent electrode material-demonstrate excellent electronic performances, but film brittleness, low infrared transmittance and low abundance limit suitability for certain industrial applications. Alternatives to indium tin oxide have recently been reported and include conducting polymers, carbon nanotubes and graphene. However, although flexibility is greatly improved, the optoelectronic performance of these carbon-based materials is limited by low conductivity. Other examples include metal nanowire-based electrodes, which can achieve sheet resistances of less than 10Ω □(-1) at 90% transmission because of the high conductivity of the metals. To achieve these performances, however, metal nanowires must be defect-free, have conductivities close to their values in bulk, be as long as possible to minimize the number of wire-to-wire junctions, and exhibit small junction resistance. Here, we present a facile fabrication process that allows us to satisfy all these requirements and fabricate a new kind of transparent conducting electrode that exhibits both superior optoelectronic performances (sheet resistance of ~2Ω □(-1) at 90% transmission) and remarkable mechanical flexibility under both stretching and bending stresses. The electrode is composed of a free-standing metallic nanotrough network and is produced with a process involving electrospinning and metal deposition. We demonstrate the practical suitability of our transparent conducting electrode by fabricating a flexible touch-screen device and a transparent conducting tape.

  14. Synthesis and heavy metal immobilization behaviors of slag based geopolymer.

    Science.gov (United States)

    Yunsheng, Zhang; Wei, Sun; Qianli, Chen; Lin, Chen

    2007-05-08

    In this paper, two aspects of studies are carried out: (1) synthesis of geopolymer by using slag and metakaolin; (2) immobilization behaviors of slag based geopolymer in a presence of Pb and Cu ions. As for the synthesis of slag based geopolymer, four different slag content (10%, 30%, 50%, 70%) and three types of curing regimes (standard curing, steam curing and autoclave curing) are investigated to obtain the optimum synthesis condition based on the compressive and flexural strength. The testing results showed that geopolymer mortar containing 50% slag that is synthesized at steam curing (80 degrees C for 8h), exhibits higher mechanical strengths. The compressive and flexural strengths of slag based geopolymer mortar are 75.2 MPa and 10.1 MPa, respectively. Additionally, Infrared (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques are used to characterize the microstructure of the slag based geopolymer paste. IR spectra show that the absorptive band at 1086 cm(-1) shifts to lower wave number around 1007 cm(-1), and some six-coordinated Als transforms into four-coordination during the synthesis of slag based geopolymer paste. The resulting slag based geopolymeric products are X-ray amorphous materials. SEM observation shows that it is possible to have geopolymeric gel and calcium silicate hydrate (C-S-H) gel forming simultaneously within slag based geopolymer paste. As for immobilization of heavy metals, the leaching tests are employed to investigate the immobilization behaviors of the slag based geopolymer mortar synthesized under the above optimum condition. The leaching tests show that slag based geopolymer mortar can effectively immobilize Cu and Pb heavy metal ions, and the immobilization efficiency reach 98.5% greater when heavy metals are incorporated in the slag geopolymeric matrix in the range of 0.1-0.3%. The Pb exhibits better immobilization efficiency than the Cu in the case of large dosages of heavy metals.

  15. Schiff base transition metal complexes for Suzuki–Miyaura cross ...

    Indian Academy of Sciences (India)

    RASHEEDA M ANSARI

    2017-08-19

    Aug 19, 2017 ... Abstract. Schiff base ligand and its complex with iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) ions were synthesized using 4-aminoacetophenone and salicylaldehyde and characterized. FTIR spectrum shows that bidentate coordination of metal ions with ligand where O, N are electron donating sites of ...

  16. Shear Zone-Hosted Base Metal Mineralization near Abraha ...

    African Journals Online (AJOL)

    Low-grade basement rocks of Neoproterozoic age with well developed shear zones and posttectonic granitic intrusives from Hawzien area of northern Ethiopia were studied for field characteristics, mineralogy, textures, alteration assemblages and geochemistry to explore their potential for base metal mineralization.

  17. Synthesis, spectral characterization of Schiff base transition metal ...

    Indian Academy of Sciences (India)

    TECS

    Synthesis, spectral characterization of Schiff base transition metal complexes: DNA cleavage and antimicrobial activity studies. N RAMAN,* J DHAVEETHU RAJA and A SAKTHIVEL. Department of Chemistry, VHNSN College, Virudhunagar 626 001 e-mail: drn_ raman@yahoo.co.in. MS received 1 May 2007; revised 7 July ...

  18. Schiff base transition metal complexes for Suzuki–Miyaura cross ...

    Indian Academy of Sciences (India)

    Schiff base ligand and its complex with iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) ions were synthesized using 4-aminoacetophenone and salicylaldehyde and characterized. FTIR spectrum shows that bidentate coordination of metal ions with ligand where O, N are electron donating sites of azomethine group.

  19. Phenalenyl-based ligand for transition metal chemistry: Application ...

    Indian Academy of Sciences (India)

    mandal@iiserkol.ac.in. Abstract. We report the synthesis and characterization of the first transition metal complex of a phenalenyl- based ligand. The reaction of Cu(OAc)2.H2O with 9-N-methylamino-1-N -methylimino-phenalene (LH) in 1:1.

  20. Tridentate Schiff base (ONO) transition metal complexes: Synthesis ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 7. Tridentate Schiff base (ONO) transition metal complexes: Synthesis, crystal structure, spectroscopic and larvicidal studies. SUNDARAMURTHY SANTHA LAKSHMI KANNAPPAN GEETHA P MAHADEVI. Regular Article Volume 128 Issue 7 July 2016 pp ...

  1. Schiff base transition metal complexes for Suzuki–Miyaura cross

    Indian Academy of Sciences (India)

    Schiff base ligand and its complex with iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) ions were synthesized using 4-aminoacetophenone and salicylaldehyde and characterized. FTIR spectrum shows that bidentate coordination of metal ions with ligand where O, N are electron donating sites of azomethine group.

  2. Indicator minerals as guides to base metal sulphide mineralisation ...

    Indian Academy of Sciences (India)

    Zn-bearing minerals that act as indicator minerals for base metal sulphide mineralization from the Proterozoic Betul Belt,central India with special emphasis on their genetic significance have been discussed.Sulphide mineralisation is hosted by the felsic volcanic rocks and has similarities with volcanic-hosted massive ...

  3. Hydrometallurgical Approach for Leaching of Metals from Copper Rich Side Stream Originating from Base Metal Production

    Directory of Open Access Journals (Sweden)

    Udit Surya Mohanty

    2018-01-01

    Full Text Available Pyrometallurgical metal production results in side streams, such as dusts and slags, which are carriers of metals, though commonly containing lower metal concentrations compared to the main process stream. In order to improve the circular economy of metals, selective leaching of copper from an intermediate raw material originating from primary base metal production plant was investigated. The raw material investigated was rich in Cu (12.5%, Ni (2.6%, Zn (1.6%, and Fe (23.6% with the particle size D80 of 124 µm. The main compounds present were nickel ferrite (NiFe2O4, fayalite (Fe2SiO4, cuprite (Cu2O, and metallic copper. Leaching was studied in 16 different solutions. The results revealed that copper phases could be dissolved with high yield (>90% and selectivity towards nickel (Cu/Ni > 7 already at room temperature with the following solutions: 0.5 M HCl, 1.5 M HCl, 4 M NaOH, and 2 M HNO3. A concentration of 4 M NaOH provided a superior selectivity between Cu/Ni (340 and Cu/Zn (51. In addition, 1–2 M HNO3 and 0.5 M HCl solutions were shown to result in high Pb dissolution (>98%. Consequently, 0.5 M HCl leaching is suggested to provide a low temperature, low chemical consumption method for selective copper removal from the investigated side stream, resulting in PLS (pregnant leach solution which is a rich in Cu and lead free residue, also rich in Ni and Fe.

  4. Metallic component with a chromium carbide base protective coating

    International Nuclear Information System (INIS)

    Wolfla, T.A.; Tucker, R.C. Jr.

    1976-01-01

    The invention concerns a coating system to protect metal components in sodium and helium cooled nuclear reactors. It includes a nickel or iron based alloy metal substrate, a first coat formed on the substrate and comprising chromium carbides and a binder selected among the chromium-nickel, chromium-cobalt, chromium-iron alloys and the super-alloys, the first coating being between 25 and 380 microns thick, and a surface coating comprising pure chromium carbides and being between 12.5 and 125 microns thick [fr

  5. Chemical sensors based on molecularly modified metallic nanoparticles

    International Nuclear Information System (INIS)

    Haick, Hossam

    2007-01-01

    This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

  6. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-08-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  7. Quantum-based Atomistic Simulation of Transition Metals

    International Nuclear Information System (INIS)

    Moriarty, J A; Benedict, L X; Glosli, J N; Hood, R Q; Orlikowski, D A; Patel, M V; Soderlind, P; Streitz, F H; Tang, M; Yang, L H

    2005-01-01

    First-principles generalized pseudopotential theory (GPT) provides a fundamental basis for transferable multi-ion interatomic potentials in d-electron transition metals within density-functional quantum mechanics. In mid-period bcc metals, where multi-ion angular forces are important to structural properties, simplified model GPT or MGPT potentials have been developed based on canonical d bands to allow analytic forms and large-scale atomistic simulations. Robust, advanced-generation MGPT potentials have now been obtained for Ta and Mo and successfully applied to a wide range of structural, thermodynamic, defect and mechanical properties at both ambient and extreme conditions of pressure and temperature. Recent algorithm improvements have also led to a more general matrix representation of MGPT beyond canonical bands allowing increased accuracy and extension to f-electron actinide metals, an order of magnitude increase in computational speed, and the current development of temperature-dependent potentials

  8. Structure and properties of transition metal-metalloid glasses based on refractory metals

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.L.; Williams, A.R.

    1979-01-01

    The structure and properties of several new transition metal-metalloid (TM/sub 1-x/M/sub x/) metallic glasses based on refractory transition metals (e.g. Mo, W, Ru etc.) have been systemically investigated as a function of composition. The structure of the alloys has been investigated by x-ray diffraction methods and measurements of superconducting properties, electrical resistivity, density, hardness, and mechanical behavior were made. These data are used in developing a novel description of the structure of TM/sub 1-x/M/sub x/ glasses. The experimental evidence suggests that an ideal amorphous phase forms at a specific composition x/sub c/ and that this phase has a well defined atomic short range order. For metallic glasses having x < x/sub c/ (metalloid poor glasses) vacancy-like defects form, which are characterized by the excess volume which they contribute to the glass. Another, as yet unspecified defect appears to form in glasses with x > x/sub c/. This novel picture can explain the variation of many properties of these glasses with metalloid concentration.

  9. Acceptorless dehydrogenation of small molecules through cooperative base metal catalysis.

    Science.gov (United States)

    West, Julian G; Huang, David; Sorensen, Erik J

    2015-12-11

    The dehydrogenation of unactivated alkanes is an important transformation both in industrial and biological systems. Recent efforts towards this reaction have revolved around high temperature, organometallic C-H activation by noble metal catalysts that produce alkenes and hydrogen gas as the sole products. Conversely, natural desaturase systems proceed through stepwise hydrogen atom transfer at physiological temperature; however, these transformations require a terminal oxidant. Here we show combining tetra-n-butylammonium decatungstate (TBADT) and cobaloxime pyridine chloride (COPC) can catalytically dehydrogenate unactivated alkanes and alcohols under near-UV irradiation at room temperature with hydrogen as the sole by-product. This noble metal-free process follows a nature-inspired pathway of high- and low-energy hydrogen atom abstractions. The hydrogen evolution ability of cobaloximes is leveraged to render the system catalytic, with cooperative turnover numbers up to 48 and yields up to 83%. Our results demonstrate how cooperative base metal catalysis can achieve transformations previously restricted to precious metal catalysts.

  10. Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Zhenzhong Guo

    2016-10-01

    Full Text Available The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclusion and future expectations are described herein.

  11. Development of a thermodynamic data base for selected heavy metals

    International Nuclear Information System (INIS)

    Hageman, Sven; Scharge, Tina; Willms, Thomas

    2015-07-01

    The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.

  12. Magnetic properties of fcc Ni-based transition metal alloy

    Czech Academy of Sciences Publication Activity Database

    Kudrnovský, Josef; Drchal, Václav

    2009-01-01

    Roč. 100, č. 9 (2009), s. 1193-1196 ISSN 1862-5282 R&D Projects: GA MŠk OC 150; GA AV ČR IAA100100616 Institutional research plan: CEZ:AV0Z10100520 Keywords : transition metal alloys * Ni-based * pair exchange interactions * Curie temperatures * renormalized RPA Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.862, year: 2009

  13. GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

    KAUST Repository

    Khan, Mujeeb

    2015-06-11

    Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

  14. Theoretical bases on thermal stability of layered metallic systems

    International Nuclear Information System (INIS)

    Kadyrzhanov, K.K.; Rusakov, V.S.; Turkebaev, T.Eh.; Zhankadamova, A.M.; Ensebaeva, M.Z.

    2003-01-01

    The paper is dedicated to implementation of the theoretical bases for layered metallic systems thermal stabilization. The theory is based on the stabilization mechanism expense of the intermediate two-phase field formation. As parameters of calculated model are coefficients of mutual diffusion and inclusions sizes of generated phases in two-phase fields. The stabilization time dependence for beryllium-iron (Be (1.1 μm)-Fe(5.5 μm)) layered system from iron and beryllium diffusion coefficients, and inclusions sizes is shown as an example. Conclusion about possible mechanisms change at transition from microscopic consideration to the nano-crystal physics level is given

  15. Heavy metals contamination and their risk assessment around the abandoned base metals and Au-Ag mines in Korea

    Science.gov (United States)

    Chon, Hyo-Taek

    2017-04-01

    Heavy metals contamination in the areas of abandoned Au-Ag and base metal mines in Korea was investigated in order to assess the level of metal pollution, and to draw general summaries about the fate of toxic heavy metals in different environments. Efforts have been made to compare the level of heavy metals, chemical forms, and plant uptake of heavy metals in each mine site. In the base-metals mine areas, significant levels of Cd, Cu, Pb and Zn were found in mine dump soils developed over mine waste materials and tailings. Leafy vegetables tend to accumulate heavy metals(in particular, Cd and Zn) higher than other crop plants, and high metal concentrations in rice crops may affect the local residents' health. In the Au-Ag mining areas, arsenic would be the most characteristic contaminant in the nearby environment. Arsenic and heavy metals were found to be mainly associated with sulfide gangue minerals, and the mobility of these metals would be enhanced by the effect of continuing weathering and oxidation. According to the sequential extraction of metals in soils, most heavy metals were identified as non-residual chemical forms, and those are very susceptible to the change of ambient conditions of a nearby environment. The concept of pollution index(PI) of soils gives important information on the extent and degree of multi-element contamination, and can be applied to the evaluation of mine soils before their agricultural use and remediation. The risk assessment process comprising exposure assessment, dose-response assessment, and risk characterization was discussed, and the results of non-cancer risk of As, Cd, and Zn, and those of cancer risk of As were suggested.

  16. Constructing metal-based structures on nanopatterned etched silicon.

    Science.gov (United States)

    Zhang, Xiaojiang; Qiao, Yinghong; Xu, Lina; Buriak, Jillian M

    2011-06-28

    Silicon surfaces with nanoscale etched patterns were obtained using polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer films as templates, followed by brief immersion in HF(aq). The resulting interfaces were comprised of pseudohexagonal arrays of pits on the silicon, whose shapes depended upon the chosen silicon orientation. The top unetched face of silicon remains capped by the native oxide, and the pit interiors are terminated by Si-H(x). Selective chemical functionalization via these two chemical handles was demonstrated to be a viable approach toward building nanostructured metal oxide and metal features within these silicon pits and on the top face. Using a series of interfacial chemical reactions, including oxidation (of Si-H(x)-terminated regions), hydrosilylation, and alkoxysilane-based chemistry on silicon oxide, the growth of metal-based structures can be spatially controlled. In the first approach, titania nanobowls were grown within the etch pits, and in the second, galvanic displacement was used to produce gold nanoparticles either within the etch pits, on the top silicon face, or both.

  17. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  18. High pressure die casting of Fe-based metallic glass.

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-11

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  19. Metal-composite adhesion based on diazonium chemistry.

    Science.gov (United States)

    Oweis, Yara; Alageel, Omar; Kozak, Paige; Abdallah, Mohamed-Nur; Retrouvey, Jean-Marc; Cerruti, Marta; Tamimi, Faleh

    2017-11-01

    Composite resins do not adhere well to dental alloys. This weak bond can result in failure at the composite-metal interface in fixed dental prostheses and orthodontic brackets. The aim of this study was to develop a new adhesive, based on diazonium chemistry, to facilitate chemical bonding between dental alloys and composite resin. Samples of two types of dental alloys, stainless steel and cobalt chromium were primed with a diazonium layer in order to create a surface coating favorable for composite adhesion. Untreated metal samples served as controls. The surface chemical composition of the treated and untreated samples was analyzed by X-ray photoelectron spectroscopy (XPS) and the tensile strength of the bond with composite resin was measured. The diazonium adhesive was also tested for shear bond strength between stainless steel orthodontic brackets and teeth. XPS confirmed the presence of a diazonium coating on the treated metals. The coating significantly increased the tensile and shear bond strengths by three and four folds respectively between the treated alloys and composite resin. diazonium chemistry can be used to develop composite adhesives for dental alloys. Diazonium adhesion can effectively achieve a strong chemical bond between dental alloys and composite resin. This technology can be used for composite repair of fractured crowns, for crown cementation with resin based cements, and for bracket bonding. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Terahertz Modulator based on Metamaterials integrated with Metal-Semiconductor-Metal Varactors

    Science.gov (United States)

    Nouman, Muhammad Tayyab; Kim, Hyun-Woong; Woo, Jeong Min; Hwang, Ji Hyun; Kim, Dongju; Jang, Jae-Hyung

    2016-01-01

    The terahertz (THz) band of the electromagnetic spectrum, with frequencies ranging from 300 GHz to 3 THz, has attracted wide interest in recent years owing to its potential applications in numerous areas. Significant progress has been made toward the development of devices capable of actively controlling terahertz waves; nonetheless, further advances in device functionality are necessary for employment of these devices in practical terahertz systems. Here, we demonstrate a low voltage, sharp switching terahertz modulator device based on metamaterials integrated with metal semiconductor metal (MSM) varactors, fabricated on an AlGaAs/InGaAs based heterostructure. By varying the applied voltage to the MSM-varactor located at the center of split ring resonator (SRR), the resonance frequency of the SRR-based metamaterial is altered. Upon varying the bias voltage from 0 V to 3 V, the resonance frequency exhibits a transition from 0.52 THz to 0.56 THz, resulting in a modulation depth of 45 percent with an insertion loss of 4.3 dB at 0.58 THz. This work demonstrates a new approach for realizing active terahertz devices with improved functionalities. PMID:27194128

  1. Terahertz Modulator based on Metamaterials integrated with Metal-Semiconductor-Metal Varactors.

    Science.gov (United States)

    Nouman, Muhammad Tayyab; Kim, Hyun-Woong; Woo, Jeong Min; Hwang, Ji Hyun; Kim, Dongju; Jang, Jae-Hyung

    2016-05-19

    The terahertz (THz) band of the electromagnetic spectrum, with frequencies ranging from 300 GHz to 3 THz, has attracted wide interest in recent years owing to its potential applications in numerous areas. Significant progress has been made toward the development of devices capable of actively controlling terahertz waves; nonetheless, further advances in device functionality are necessary for employment of these devices in practical terahertz systems. Here, we demonstrate a low voltage, sharp switching terahertz modulator device based on metamaterials integrated with metal semiconductor metal (MSM) varactors, fabricated on an AlGaAs/InGaAs based heterostructure. By varying the applied voltage to the MSM-varactor located at the center of split ring resonator (SRR), the resonance frequency of the SRR-based metamaterial is altered. Upon varying the bias voltage from 0 V to 3 V, the resonance frequency exhibits a transition from 0.52 THz to 0.56 THz, resulting in a modulation depth of 45 percent with an insertion loss of 4.3 dB at 0.58 THz. This work demonstrates a new approach for realizing active terahertz devices with improved functionalities.

  2. Allosterically tunable, DNA-based switches triggered by heavy metals.

    Science.gov (United States)

    Porchetta, Alessandro; Vallée-Bélisle, Alexis; Plaxco, Kevin W; Ricci, Francesco

    2013-09-11

    Here we demonstrate the rational design of allosterically controllable, metal-ion-triggered molecular switches. Specifically, we designed DNA sequences that adopt two low energy conformations, one of which does not bind to the target ion and the other of which contains mismatch sites serving as specific recognition elements for mercury(II) or silver(I) ions. Both switches contain multiple metal binding sites and thus exhibit homotropic allosteric (cooperative) responses. As heterotropic allosteric effectors we employ single-stranded DNA sequences that either stabilize or destabilize the nonbinding state, enabling dynamic range tuning over several orders of magnitude. The ability to rationally introduce these effects into target-responsive switches could be of value in improving the functionality of DNA-based nanomachines.

  3. Silicon-based metallic micro grid for electron field emission

    International Nuclear Information System (INIS)

    Kim, Jaehong; Jeon, Seok-Gy; Kim, Jung-Il; Kim, Geun-Ju; Heo, Duchang; Shin, Dong Hoon; Sun, Yuning; Lee, Cheol Jin

    2012-01-01

    A micro-scale metal grid based on a silicon frame for application to electron field emission devices is introduced and experimentally demonstrated. A silicon lattice containing aperture holes with an area of 80 × 80 µm 2 and a thickness of 10 µm is precisely manufactured by dry etching the silicon on one side of a double-polished silicon wafer and by wet etching the opposite side. Because a silicon lattice is more rigid than a pure metal lattice, a thin layer of Au/Ti deposited on the silicon lattice for voltage application can be more resistant to the geometric stress caused by the applied electric field. The micro-fabrication process, the images of the fabricated grid with 88% geometric transparency and the surface profile measurement after thermal feasibility testing up to 700 °C are presented. (paper)

  4. Seismic Base Isolation Analysis for PASCAR Liquid Metal Reactor

    International Nuclear Information System (INIS)

    Lee, Kuk Hee; Yoo, Bong; Kim, Yun Jae

    2008-01-01

    This paper presents a study for developing a seismic isolation system for the PASCAR (Proliferation resistant, Accident-tolerant, Self-supported, Capsular and Assured Reactor) liquid metal reactor design. PASCAR use lead-bismuth eutectic (LBE) as coolant. Because the density (10,000kg/m 3 ) of LBE coolant is very heavier than sodium coolant and water, this presents a challenge to designers of the seismic isolation systems that will be used with these heavy liquid metal reactors. Finite element analysis is adapted to determine the characteristics of the isolator device. Results are presented from a study on the use of three-dimensional seismic isolation devices to the full-scale reactor. The seismic analysis responses of the two-dimensional and the three-dimensional isolation systems for the PASCAR are compared with that of the conventional fixed base system

  5. Metal shell technology based upon hollow jet instability

    International Nuclear Information System (INIS)

    Kendall, J.M.; Lee, M.C.; Wang, T.G.

    1982-01-01

    Spherical shells of submillimeter size are sought as ICF targets. Such shells must be dimensionally precise, smooth, of high strength, and composed of a high atomic number material. We describe a technology for the production of shells based upon the hydrodynamic instability of an annular jet of molten metal. We have produced shells in the 0.7--2.0 mm size range using tin as a test material. Specimens exhibit good sphericity, fair concentricity, and excellent finish over most of the surface. Work involving a gold--lead--antimony alloy is in progress. Droplets of this are amorphous and possess superior surface finish. The flow of tin models that of the alloy well; experiments on both metals show that the technique holds considerable promise

  6. Simulation of metal cutting using a physically based plasticity model

    International Nuclear Information System (INIS)

    Svoboda, Ales; Lindgren, Lars-Erik; Wedberg, Dan

    2010-01-01

    Metal cutting is one of the most common metal shaping processes. Specified geometrical and surface properties are obtained by break-up of the material removed by the cutting edge into a chip. The chip formation is associated with a large strain, high strain rate and a locally high temperature due to adiabatic heating which make the modelling of cutting processes difficult. This study compares a physically based plasticity model and the Johnson–Cook model. The latter is commonly used for high strain rate applications. Both material models are implemented into the finite element software MSC.Marc and compared with cutting experiments. The deformation behaviour of SANMAC 316L stainless steel during an orthogonal cutting process is studied

  7. Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator.

    Science.gov (United States)

    Lam, K H; Sun, C L; Kwok, K W; Chan, H L W

    2009-07-01

    A piezoelectric dispenser has been fabricated based on the idea of a piezoelectric-metal-cavity (PMC) actuator. The PMC actuator consists of a metal ring sandwiched between two identical piezoelectric unimorphs. The radial contraction of the piezoelectric ceramic is converted into a flextensional motion of the unimorph, causing a large flexural displacement in the center part of the actuator. With the PMC actuator as a fluid chamber, the large flexural actuation can be used to produce the displacement needed to eject fluid. By applying an appropriate voltage to the piezoelectric unimorphs, a drop-on-demand ejection of ink or water can be achieved. The efficiency of fluid ejection can be enhanced after installing a valve in the fluid chamber. With the simple PMC structure, the dispenser can be operated with a low driving voltage of 12-15 V.

  8. Leachability of metals from sludge-based artificial lightweight aggregate

    Energy Technology Data Exchange (ETDEWEB)

    Chang, F.-C. [Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan (China); Lo, S.-L. [Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan (China)]. E-mail: sllo@ccms.ntu.edu.tw; Lee, M.-Y. [Department of Civil Engineering, National Central University, 300 Jhongda Road, Jhongli 320, Taiwan (China); Ko, C.-H. [Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan (China); Lin, J.-D. [Department of Civil Engineering, National Central University, 300 Jhongda Road, Jhongli 320, Taiwan (China); Huang, S.-C. [Department of Atomic Science, National Tsing Hua University, 101, Sec. 2, Kuang Fu Road, Hsinchu 300, Taiwan (China); Wang, C.-F. [Department of Atomic Science, National Tsing Hua University, 101, Sec. 2, Kuang Fu Road, Hsinchu 300, Taiwan (China)

    2007-07-19

    Metal sludge from industrial wastewater treatment plants was mixed with mining residues to be recycled into lightweight aggregate (LWA) through sintering at different temperatures. The physical properties of the LWA thus obtained were examined by scanning electron microscopy analyzer (SEM) coupled with an energy dispersive X-ray analyzer (EDX). The sequential extraction method combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) was employed to determine the concentration and distribution of hazardous toxic elements in the metal sludge-based artificial LWA. The results show that the leaching concentrations of Cd, Cr, Cu, and Pb present in the non-sintered raw aggregate pellets reached 7.4, 68.0, 96.0, and 61.4 mg/l, respectively, far exceeding the regulatory threshold. Sintering at 1150 deg. C for 15 min results in stronger chemical bonds being formed between the elements. Hence, after the first three steps of sequential extraction, the concentrations of Cr, Cu, and Pb reached 2.69, 1.50, and 1.88 mg/l at 1150 deg. C, while the final residues had total concentrations of 96.1, 88.4, and 60.6 mg/kg, respectively, with Cd undetected in both phases. The concentration levels fell within the regulatory threshold, indicating that the LWA fabricated from recycled metal sludge contains elements that are toxic and hazardous but not leached. Having no harmful effect on the environment, the metal sludge-based artificial LWA is not only safe but also practical with good physical properties.

  9. Metal-organic frameworks based membranes for liquid separation.

    Science.gov (United States)

    Li, Xin; Liu, Yuxin; Wang, Jing; Gascon, Jorge; Li, Jiansheng; Van der Bruggen, Bart

    2017-11-27

    Metal-organic frameworks (MOFs) represent a fascinating class of solid crystalline materials which can be self-assembled in a straightforward manner by the coordination of metal ions or clusters with organic ligands. Owing to their intrinsic porous characteristics, unique chemical versatility and abundant functionalities, MOFs have received substantial attention for diverse industrial applications, including membrane separation. Exciting research activities ranging from fabrication strategies to separation applications of MOF-based membranes have appeared. Inspired by the marvelous achievements of MOF-based membranes in gas separations, liquid separations are also being explored for the purpose of constructing continuous MOFs membranes or MOF-based mixed matrix membranes. Although these are in an emerging stage of vigorous development, most efforts are directed towards improving the liquid separation efficiency with well-designed MOF-based membranes. Therefore, as an increasing trend in membrane separation, the field of MOF-based membranes for liquid separation is highlighted in this review. The criteria for judicious selection of MOFs in fabricating MOF-based membranes are given. Special attention is paid to rational design strategies for MOF-based membranes, along with the latest application progress in the area of liquid separations, such as pervaporation, water treatment, and organic solvent nanofiltration. Moreover, some attractive dual-function applications of MOF-based membranes in the removal of micropollutants, degradation, and antibacterial activity are also reviewed. Finally, we define the remaining challenges and future opportunities in this field. This Tutorial Review provides an overview and outlook for MOF-based membranes for liquid separations. Further development of MOF-based membranes for liquid separation must consider the demands of strict separation standards and environmental safety for industrial application.

  10. Metal-directed topological diversity of three fluorescent metal-organic frameworks based on a new tetracarboxylate strut

    KAUST Repository

    Lou, Xinhua

    2013-01-01

    Three d- or p-block metal ions based metal-organic frameworks (MOFs) were isolated by employing a new tetracarboxylate linker, featuring unusual flu, self-interpenetrated lvt and new (3,5)-c topological nets, respectively. Interesting photoluminescent properties of these solid-state materials were also observed. © 2013 The Royal Society of Chemistry.

  11. Metal based SOD mimetic therapeutic agents: Synthesis, characterization and biochemical studies of metal complexes

    Directory of Open Access Journals (Sweden)

    J. Joseph

    2017-05-01

    Full Text Available Coordination compounds of Fe(III, Co(II, Ni(II, Cu(II and Zn(II with the Schiff base obtained through the condensation of L1 and L2 (L1 – obtained through the condensation of 4-aminoantipyrine with furfuraldehyde and L2 – derived from 2-aminobenzothiazole and 3-nitrobenzaldehyde were synthesized under reflux conditions. The newly formed complexes were characterized using elemental analysis, magnetic susceptibility, molar conductance, 1H NMR, UV–Vis., IR and ESR techniques. Cyclic voltammogram of the complexes in DMSO solution at 300 K was recorded and their salient features were summarized. The X-band ESR spectrum of the copper complex in DMSO solution at 300 and 77 K was recorded. The in vitro biological screening of the investigated compounds was tested against the bacterial species, and fungal species by disc diffusion method. The antimicrobial activity of metal complexes was dependent on the microbial species tested, ligand and the metal salts used. A comparative study of inhibition values of Schiff bases and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. The DNA binding studies were performed for the complexes using cyclic voltammetry and electronic absorption spectra. Superoxide dismutase activity of these complexes has also been examined.

  12. Spectrophotometric study of some metal ions using some Schiff's bases

    International Nuclear Information System (INIS)

    Elnager, Nawal Mohomed Ibrahim

    2000-05-01

    In this work two schiff bases namely N,N Bis(benzoyl acetone)-o-phenylene diamine (NNBBPD) and N,N Bis(benzoyl acetone)-isopropylene diamine (NNBBAID) were prepared by direct coupling of benzoyl acetone with o-phenylene and isopropylene diamine respectively. The two reagents were identified by IR spectra, thin layer chromatography (TLC) and determination of the percentage of nitrogen contents (N%). It is found that the two reagents form coloured chelates with Fe (II), Fe (III), Cu (II), U (VI), Ni (II) and Co (II). The two reagents were used for the determination of Fe (II), Fe (III) and U (VI). The formulate of these metal ion complexes were obtained using continuous variations, mole ratio and slope ratio methods. Effect of two micelles, namely sodium n-dodecyl sulphate (SDS) and hexadecyl pyridinum broinide monohydrate (HPB) on metal ion complexes were studied. It is found that both of them increase the solubility and the absorbances of the metal ion complexes with variable effects of the absorption maxima. Calibration curves for Fe (II), Fe (II) and U (VI) were obtained in optimum conditions of pH and micelles solutions. (Author)

  13. Spintronic materials and devices based on antiferromagnetic metals

    Directory of Open Access Journals (Sweden)

    Y.Y. Wang

    2017-04-01

    Full Text Available In this paper, we review our recent experimental developments on antiferromagnet (AFM spintronics mainly comprising Mn-based noncollinear AFM metals. IrMn-based tunnel junctions and Hall devices have been investigated to explore the manipulation of AFM moments by magnetic fields, ferromagnetic materials and electric fields. Room-temperature tunneling anisotropic magnetoresistance based on IrMn as well as FeMn has been successfully achieved, and electrical control of the AFM exchange spring is realized by adopting ionic liquid. In addition, promising spin-orbit effects in AFM as well as spin transfer via AFM spin waves reported by different groups have also been reviewed, indicating that the AFM can serve as an efficient spin current source. To explore the crucial role of AFM acting as efficient generators, transmitters, and detectors of spin currents is an emerging topic in the field of magnetism today. AFM metals are now ready to join the rapidly developing fields of basic and applied spintronics, enriching this area of solid-state physics and microelectronics.

  14. Multifunctional methacrylate-based coatings for glass and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pospiech, Doris, E-mail: pospiech@ipfdd.de [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Jehnichen, Dieter [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Starke, Sandra; Müller, Felix [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Technische Universität Dresden, Organic Chemistry of Polymers, Dresden (Germany); Bünker, Tobias [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Wollenberg, Anne [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Technische Universität Dresden, Organic Chemistry of Polymers, Dresden (Germany); Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Opitz, Michael; Kruspe, Rainer [IDUS Biologisch Analytisches Umweltlabor GmbH, Ottendorf-Okrilla (Germany)

    2017-03-31

    Highlights: • New methacrylate-based copolymers synthesized by free radical polymerization. • Comonomer AAMA was able to complex Cu (II) ions in solvent annealing procedure. • Coatings had efficient anti-biofouling efficacy. - Abstract: In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating’s upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  15. Multifunctional methacrylate-based coatings for glass and metal surfaces

    International Nuclear Information System (INIS)

    Pospiech, Doris; Jehnichen, Dieter; Starke, Sandra; Müller, Felix; Bünker, Tobias; Wollenberg, Anne; Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich; Opitz, Michael; Kruspe, Rainer

    2017-01-01

    Highlights: • New methacrylate-based copolymers synthesized by free radical polymerization. • Comonomer AAMA was able to complex Cu (II) ions in solvent annealing procedure. • Coatings had efficient anti-biofouling efficacy. - Abstract: In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating’s upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  16. ACCEPTABILITY ENVELOPE FOR METAL HYDRIDE-BASED HYDROGEN STORAGE SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, B.; Corgnale, C.; Tamburello, D.; Garrison, S.; Anton, D.

    2011-07-18

    The design and evaluation of media based hydrogen storage systems requires the use of detailed numerical models and experimental studies, with significant amount of time and monetary investment. Thus a scoping tool, referred to as the Acceptability Envelope, was developed to screen preliminary candidate media and storage vessel designs, identifying the range of chemical, physical and geometrical parameters for the coupled media and storage vessel system that allow it to meet performance targets. The model which underpins the analysis allows simplifying the storage system, thus resulting in one input-one output scheme, by grouping of selected quantities. Two cases have been analyzed and results are presented here. In the first application the DOE technical targets (Year 2010, Year 2015 and Ultimate) are used to determine the range of parameters required for the metal hydride media and storage vessel. In the second case the most promising metal hydrides available are compared, highlighting the potential of storage systems, utilizing them, to achieve 40% of the 2010 DOE technical target. Results show that systems based on Li-Mg media have the best potential to attain these performance targets.

  17. Ultramicrosensors based on transition metal hexacyanoferrates for scanning electrochemical microscopy

    Directory of Open Access Journals (Sweden)

    Maria A. Komkova

    2013-10-01

    Full Text Available We report here a way for improving the stability of ultramicroelectrodes (UME based on hexacyanoferrate-modified metals for the detection of hydrogen peroxide. The most stable sensors were obtained by electrochemical deposition of six layers of hexacyanoferrates (HCF, more specifically, an alternating pattern of three layers of Prussian Blue and three layers of Ni–HCF. The microelectrodes modified with mixed layers were continuously monitored in 1 mM hydrogen peroxide and proved to be stable for more than 5 h under these conditions. The mixed layer microelectrodes exhibited a stability which is five times as high as the stability of conventional Prussian Blue-modified UMEs. The sensitivity of the mixed layer sensor was 0.32 A·M−1·cm−2, and the detection limit was 10 µM. The mixed layer-based UMEs were used as sensors in scanning electrochemical microscopy (SECM experiments for imaging of hydrogen peroxide evolution.

  18. Biomedical application of hierarchically built structures based on metal oxides

    Science.gov (United States)

    Korovin, M. S.; Fomenko, A. N.

    2017-12-01

    Nowadays, the use of hierarchically built structures in biology and medicine arouses much interest. The aim of this work is to review and summarize the available literature data about hierarchically organized structures in biomedical application. Nanoparticles can serve as an example of such structures. Medicine holds a special place among various application methods of similar systems. Special attention is paid to inorganic nanoparticles based on different metal oxides and hydroxides, such as iron, zinc, copper, and aluminum. Our investigations show that low-dimensional nanostructures based on aluminum oxides and hydroxides have an inhibitory effect on tumor cells and possess an antimicrobial activity. At the same time, it is obvious that the large-scale use of nanoparticles by humans needs to thoroughly study their properties. Special attention should be paid to the study of nanoparticle interaction with living biological objects. The numerous data show that there is no clear understanding of interaction mechanisms between nanoparticles and various cell types.

  19. SVM-based base-metal prospectivity modeling of the Aravalli Orogen, Northwestern India

    Science.gov (United States)

    Porwal, Alok; Yu, Le; Gessner, Klaus

    2010-05-01

    The Proterozoic Aravalli orogen in the state of Rajasthan, northwestern India, constitutes the most important metallogenic province for base-metal deposits in India and hosts the entire economically viable lead-zinc resource-base of the country. The orogen evolved through near-orderly Wilson cycles of repeated extensional and compressional tectonics resulting in sequential opening and closing of intracratonic rifts and amalgamation of crustal domains during a circa 1.0-Ga geological history from 2.2 Ga to 1.0 Ga. This study develops a conceptual tectonostratigraphic model of the orogen based on a synthesis of the available geological, geophysical and geochronological data followed by deep-seismic-reflectivity-constrained 2-D forward gravity modeling, and links it to the Proterozoic base-metal metallogeny in the orogen in order to identify key geological controls on the base-metal mineralization. These controls are translated into exploration criteria for base-metal deposits, validated using empirical spatial analysis, and used to derive input spatial variables for model-based base-metal prospectivity mapping of the orogen. A support vector machine (SVM) algorithm augmented by incorporating a feature selection procedure is used in a GIS environment to implement the prospectivity mapping. A comparison of the SVM-derived prospectivity map with the ones derived using other established models such as neural-networks, logistic regression, and Bayesian weights-of-evidence indicates that the SVM outperforms other models, which is attributed to the capability of the SVM to return robust classification based on small training datasets.

  20. Charge transport in metal oxide nanocrystal-based materials

    OpenAIRE

    Runnerstrom, Evan Lars

    2016-01-01

    There is probably no class of materials more varied, more widely used, or more ubiquitous than metal oxides. Depending on their composition, metal oxides can exhibit almost any number of properties. Of particular interest are the ways in which charge is transported in metal oxides: devices such as displays, touch screens, and smart windows rely on the ability of certain metal oxides to conduct electricity while maintaining visible transparency. Smart windows, fuel cells, and other electrochem...

  1. Multifunctional methacrylate-based coatings for glass and metal surfaces

    Science.gov (United States)

    Pospiech, Doris; Jehnichen, Dieter; Starke, Sandra; Müller, Felix; Bünker, Tobias; Wollenberg, Anne; Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich; Opitz, Michael; Kruspe, Rainer

    2017-03-01

    In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating's upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  2. Memory phenomenon in a lanthanum based bulk metallic glass

    International Nuclear Information System (INIS)

    Zhou, Ye; Huang, Wei Min; Zhao, Yong; Ding, Zhen; Li, Yan; Tor, Shu Beng; Liu, Erjia

    2016-01-01

    In this paper, we experimentally investigate two memory phenomena in a lanthanum based bulk metallic glass (BMG). While the temperature memory effect (TME) is not found by differential scanning calorimeter (DSC) test, shape recovery is observed in samples indented at both low and high temperatures. In terms of shape memory related characteristics, this BMG shares some features of shape memory alloys (SMAs) due to its metal nature, and some other features of shape memory polymers (SMPs) owing to its glassy–rubbery transition. The formation of protrusion in the polished sample after heating to super-cooled liquid region (SCLR) indicates that surface tension is not a necessarily positive contributor for shape recovery. Release of internal elastic stress is concluded as the major player. Although the amorphous nature of BMGs enables for storing appreciable amount of internal elastic stress upon deformation, without the presence of cross-linker as in typical SMPs, the shape recovery in BMGs is rather limited. - Highlights: • Experimental investigation of shape recovery in BMG. • Surface tension is not the major reason for shape recovery in BMG. • Release of internal stress is the major contributor for shape recovery. • Comparison of shape memory features of BMG with other shape memory materials.

  3. Evaluation of different finish line designs in base metal alloys

    Directory of Open Access Journals (Sweden)

    Aghandeh R

    1999-06-01

    Full Text Available This investigation was performed according to the widespread application of base metal alloys"nand few articles published about the marginal integrity of restorations fabricated by these metals."nThree standard dies of a maxillary first premolar were prepared with a flat shoulder finish line in buccal"naspect and chamfer in palatal. One of them left with no change. On the buccal aspect of the second and"nthird dies 135?and 1607 bevel were added respectively"nUsing dual wax technique, nine wax patterns were formed on each die and casting procedure of selected"nnon precious alloy was performed by centrifugal method. Marginal gaps of each copping seated on dies"nwere measured by scanning electron microscope (SEM with X500 magnification. Measurements were"ndone on three areas of marked dies on buccal aspect. Measurement son palatal aspect was done on"nmarked midpalatal point as control."nResults and statistical analysis showed no significant difference among marginal gaps in lingual aspect."nBut on the buccal aspect there were statistically significant differences among the groups (P<0.001. Flat"nshoulder had the best marginal integrity (mean 4 micron. Shoulder with 160' bevel had the most marginal"ngap (mean 26.5 micron and shoulder with 1357 bevel was between two other groups (mean 15.7 micron.

  4. Process for recovering uranium and other base metals

    International Nuclear Information System (INIS)

    Jan, R. J-J.

    1979-01-01

    Uranium and other base metals are leached from their ores with aqueous solutions containing bicarbonate ions that have been generated or reconstituted by converting other non-bicarbonate anions into bicarbonate ions. The conversion is most conveniently effected by contacting solutions containing SO 4 - and Cl - ions with a basic anion exchange resin so that the SO 4 - and Cl - ions are converted into or exhanged for HCO 3 - ions. CO 2 may be dissolved in the solution so it is present during the exhange. The resin is preferably in bicarbonate form prior to contact and CO 2 partial pressure is adjusted so that the resin is not fouled by depositing metal precipitates. In-situ uranium mining is conducted by circulating such solutions through the ore deposit. Oxidizing agents are included in the injected lixiviant. The leaching strength of the circulating bicarbonate lixiviant is maintained by converting the anions generated during leaching or above-ground recovery processes into HCO 3 - ions. The resin may conveniently be eluted and reformed intermittently

  5. Process for recovering uranium and other base metals

    International Nuclear Information System (INIS)

    Jan, R.J.

    1981-01-01

    Uranium and other base metals are leached from their ores with aqueous solutions containing bicarbonate ions that have been generated or reconstituted by converting other non-bicarbonate anions into bicarbonate ions. The conversion is most conveniently effected by contacting solutions containing SO 4 -- and C1 - ions with a basic anion exchange resin so that the SO 4 -- and Cl - ions are converted into or exchanged for HCO 3 - ions. CO 2 may be dissolved in the solution so it is present during the exchange. The resin is preferably in bicarbonate form prior to contact and CO 2 partial pressure is adjusted so that the resin is not fouled by depositing metal precipitates. In-situ uranium mining is conducted by circulating such solutions through the ore deposit. Oxidizing agents are included in the injected lixiviant. The leaching strength of the circulating bicarbonate lixiviant is maintained by converting the anions generated during leaching or above-ground recovery processes into HCO 3 - ions. The resin may conveniently be eluted and performed intermittently. (author)

  6. Process for recovering uranium and other base metals

    International Nuclear Information System (INIS)

    Jan, R.J.

    1984-01-01

    Uranium and other base metals are leached from their ores with aqueous solutions containing bicarbonate ions that have been generated or reconstituted by converting other non-bicarbonate anions into bicarbonate ions. The conversion is most conveniently effected by contacting solutions containing SO 4 2- and Cl - ions with a basic anion exchange resin so that the SO 4 2- and Cl - ions are converted into or exchanged for HCO 3 - ions. CO 2 may be dissolved in the solution so it is present during the exchange. The resin is preferably in bicarbonate form prior to contact and CO 2 partial pressure is adjusted so that the resin is not fouled by depositing metal precipitates. In-situ uranium mining is conducted by circulating such solutions through the ore deposit. Oxidizing agents are included in the injected lixiviant. The leaching strength of the circulating bicarbonate lixiviant is maintained by converting the anions generated during leaching or above-ground recovery processes into HCO 3 - ions. The resin may conveniently be eluted and reformed intermittently

  7. Compact-Morphology-based poly-metallic Nodule Delineation.

    Science.gov (United States)

    Schoening, Timm; Jones, Daniel O B; Greinert, Jens

    2017-10-17

    Poly-metallic nodules are a marine resource considered for deep sea mining. Assessing nodule abundance is of interest for mining companies and to monitor potential environmental impact. Optical seafloor imaging allows quantifying poly-metallic nodule abundance at spatial scales from centimetres to square kilometres. Towed cameras and diving robots acquire high-resolution imagery that allow detecting individual nodules and measure their sizes. Spatial abundance statistics can be computed from these size measurements, providing e.g. seafloor coverage in percent and the nodule size distribution. Detecting nodules requires segmentation of nodule pixels from pixels showing sediment background. Semi-supervised pattern recognition has been proposed to automate this task. Existing nodule segmentation algorithms employ machine learning that trains a classifier to segment the nodules in a high-dimensional feature space. Here, a rapid nodule segmentation algorithm is presented. It omits computation-intense feature-based classification and employs image processing only. It exploits a nodule compactness heuristic to delineate individual nodules. Complex machine learning methods are avoided to keep the algorithm simple and fast. The algorithm has successfully been applied to different image datasets. These data sets were acquired by different cameras, camera platforms and in varying illumination conditions. Their successful analysis shows the broad applicability of the proposed method.

  8. Metal content of Dendrobaena rubida (Oligochaeta) in a base metal mining area

    Energy Technology Data Exchange (ETDEWEB)

    Ireland, M.P.

    1975-01-01

    Metal analysis of soils collected near disused lead and zinc mines showed high concentrations of total iron, zinc, lead and available lead, together with free iron. Field and experimental studies on the metal content of the earthworm Dendrobaena rubida (Savigny) living in soils of high and low metal levels showed that the earthworms probably regulated the iron and zinc content of the tissues but retained lead. It is tentatively suggested that soil calcium may influence the uptake of metals by D. rubida while the results for tissue lead content appeared to show a direct effect of calcium on lead by the regulation of endogenous tissue calcium. (auth)

  9. Resistive switching in ZrO2 based metal-oxide-metal structures

    International Nuclear Information System (INIS)

    Kaerkkaenen, Irina

    2014-01-01

    The goal of this work is a deeper understanding of the influence of the (i) metal-oxide-metal (MOM) layer stacks configuration, (ii) the oxide films microstructure, (iii) and their defect structure on the appearance of different switching modes, i.e. unipolar (UP) and bipolar (BP). The first part deals with the fabrication of ZrO 2 thin films by an industrial compatible atomic layer deposition (ALD) process, the chemical, structural and morphological characterization of the films, the growth of ZrO 2 /TiO 2 bilayers, the integration of the layers into metal-oxide-metal (MOM) devices and the electrical characterization with focus on the RS behavior. In the second part the effect of the device structure, in particular the thickness of the electrochemical active electrode (EAE) and the ZrO 2 film morphology, on the RS switching polarity of Pt/ZrO 2 /(EAE) cells is discussed. ZrO 2 films and ZrO 2 /TiO 2 bilayers were grown by ALD and were carefully structurally and electrically characterized. The ZrO 2 films grown from Zr[N(CH 3 )C 2 H 5 ] 4 (TEMA-Zr) at 240 C were polycrystalline with a mixture of cubic/tetragonal phases. ALD/H 2 O-ZrO 2 films exhibited a random oriented polycrystalline structure, whereas the ALD/O 3 -ZrO 2 films consisted of preferably oriented cubic shaped grains. Pt/ZrO 2 /Ti/Pt structures with a Ti top electrode (TE) thickness of 5 to 20 nm showed unipolar type RS behavior, while by increasing the Ti TE thickness a gradual change of switching polarity from unipolar to bipolar with a completely bipolar type RS behavior for a Ti TE thickness of 40 nm is found. The switching in Pt/ZrO 2 /TiO 2 /Ti/Pt devices was unipolar, comparable to Pt/ZrO 2 /Ti/Pt cells. In contrast, bilayers with the reverse structure, Pt/TiO 2 /ZrO 2 /Ti/Pt, showed non-switching behavior. The effect of the cells stack structure on the polarity of the RS behavior was studied in detail for 20 nm thick ZrO 2 films grown by an ozone based ALD process and integrated into Pt/ZrO 2

  10. Commercial Implementation of Model-Based Manufacturing of Nanostructured Metals

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, Terry C. [Los Alamos National Laboratory

    2012-07-24

    Computational modeling is an essential tool for commercial production of nanostructured metals. Strength is limited by imperfections at the high strength levels that are achievable in nanostructured metals. Processing to achieve homogeneity at the micro- and nano-scales is critical. Manufacturing of nanostructured metals is intrinsically a multi-scale problem. Manufacturing of nanostructured metal products requires computer control, monitoring and modeling. Large scale manufacturing of bulk nanostructured metals by Severe Plastic Deformation is a multi-scale problem. Computational modeling at all scales is essential. Multiple scales of modeling must be integrated to predict and control nanostructural, microstructural, macrostructural product characteristics and production processes.

  11. Microstructure-Based Counterfeit Detection in Metal Part Manufacturing

    Science.gov (United States)

    Dachowicz, Adam; Chaduvula, Siva Chaitanya; Atallah, Mikhail; Panchal, Jitesh H.

    2017-11-01

    Counterfeiting in metal part manufacturing has become a major global concern. Although significant effort has been made in detecting the implementation of such counterfeits, modern approaches suffer from high expense during production, invasiveness during manufacture, and unreliability in practice if parts are damaged during use. In this paper, a practical microstructure-based counterfeit detection methodology is proposed, which draws on inherent randomness present in the microstructure as a result of the manufacturing process. An optical Physically Unclonable Function (PUF) protocol is developed which takes a micrograph as input and outputs a compact, unique string representation of the micrograph. The uniqueness of the outputs and their robustness to moderate wear and tear is demonstrated by application of the methodology to brass samples. The protocol is shown to have good discriminatory power even between samples manufactured in the same batch, and runs on the order of several seconds per part on inexpensive machines.

  12. A metal-based inhibitor of NEDD8-activating enzyme.

    Directory of Open Access Journals (Sweden)

    Hai-Jing Zhong

    Full Text Available A cyclometallated rhodium(III complex [Rh(ppy(2(dppz](+ (1 (where ppy=2-phenylpyridine and dppz=dipyrido[3,2-a:2',3'-c]phenazine dipyridophenazine has been prepared and identified as an inhibitor of NEDD8-activating enzyme (NAE. The complex inhibited NAE activity in cell-free and cell-based assays, and suppressed the CRL-regulated substrate degradation and NF-κB activation in human cancer cells with potency comparable to known NAE inhibitor MLN4924. Molecular modeling analysis suggested that the overall binding mode of 1 within the binding pocket of the APPBP1/UBA3 heterodimer resembled that for MLN4924. Complex 1 is the first metal complex reported to suppress the NEDDylation pathway via inhibition of the NEDD8-activating enzyme.

  13. Chitosan-based Schiff base-metal complexes (Mn, Cu, Co) as ...

    Indian Academy of Sciences (India)

    catalyst was studied using a batch reactor and gas chromatography for product identification and quantifica- tion. The results were compared against the ... It has many applications in medicine such as wound dressings, artificial ...... a stable Schiff base, which can form a com- plex with metal ion, resulting in a promising cata-.

  14. Nanofluid based on self-nanoencapsulated metal/metal alloys phase change materials with tuneable crystallisation temperature.

    Science.gov (United States)

    Navarrete, Nuria; Gimeno-Furio, Alexandra; Mondragon, Rosa; Hernandez, Leonor; Cabedo, Luis; Cordoncillo, Eloisa; Julia, J Enrique

    2017-12-14

    Nanofluids using nanoencapsulated Phase Change Materials (nePCM) allow increments in both the thermal conductivity and heat capacity of the base fluid. Incremented heat capacity is produced by the melting enthalpy of the nanoparticles core. In this work two important advances in this nanofluid type are proposed and experimentally tested. It is firstly shown that metal and metal alloy nanoparticles can be used as self-encapsulated nePCM using the metal oxide layer that forms naturally in most commercial synthesis processes as encapsulation. In line with this, Sn/SnOx nanoparticles morphology, size and thermal properties were studied by testing the suitability and performance of encapsulation at high temperatures and thermal cycling using a commercial thermal oil (Therminol 66) as the base fluid. Secondly, a mechanism to control the supercooling effect of this nePCM type based on non-eutectic alloys was developed.

  15. Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

    Directory of Open Access Journals (Sweden)

    Naomi Tanoue

    2013-07-01

    Full Text Available OBJECTIVE: The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. MATERIAL AND METHODS: Disk specimens (diameter 10 mm and thickness 2.5 mm were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1 air-abraded with 50-70-µm grain alumina (CON; 2 1 + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA; 3 1 + conditioned with a primer including a diphosphate monomer (MDP; 4 treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. RESULTS: The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05 greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. CONCLUSION: Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.

  16. In situ X-ray absorption spectroscopy of transition metal based water oxidation catalysts.

    Science.gov (United States)

    van Oversteeg, Christina H M; Doan, Hoang Q; de Groot, Frank M F; Cuk, Tanja

    2017-01-03

    X-ray absorption studies of the geometric and electronic structure of primarily heterogeneous Co, Ni, and Mn based water oxidation catalysts are reviewed. The X-ray absorption near edge and extended X-ray absorption fine structure studies of the metal K-edge, characterize the metal oxidation state, metal-oxygen bond distance, metal-metal distance, and degree of disorder of the catalysts. These properties guide the coordination environment of the transition metal oxide radical that localizes surface holes and is required to oxidize water. The catalysts are investigated both as-prepared, in their native state, and under reaction conditions, while transition metal oxide radicals are generated. The findings of many experiments are summarized in tables. The advantages of future X-ray experiments on water oxidation catalysts, which include the limited data available of the oxygen K-edge, metal L-edge, and resonant inelastic X-ray scattering, are discussed.

  17. Novel thiosalicylate-based ionic liquids for heavy metal extractions

    Energy Technology Data Exchange (ETDEWEB)

    Leyma, Raphlin; Platzer, Sonja [Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna (Austria); Jirsa, Franz [Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna (Austria); Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, 2006, Johannesburg (South Africa); Kandioller, Wolfgang, E-mail: wolfgang.kandioller@univie.ac.at [Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna (Austria); Krachler, Regina; Keppler, Bernhard K. [Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna (Austria)

    2016-08-15

    Highlights: • Six thiosalicylate-based ammonium and phosphonium ionic liquids (ILs) were newly synthesized. • ILs showed good extraction of cadmium, copper, and zinc. • Phosphonium ILs showed better extraction efficiencies than their ammonium counterparts. - Abstract: This study aims to develop novel ammonium and phosphonium ionic liquids (ILs) with thiosalicylate (TS) derivatives as anions and evaluate their extracting efficiencies towards heavy metals in aqueous solutions. Six ILs were synthesized, characterized, and investigated for their extracting efficacies for cadmium, copper, and zinc. Liquid-liquid extractions of Cu, Zn, or Cd with ILs after 1–24 h using model solutions (pH 7; 0.1 M CaCl{sub 2}) were assessed using flame atomic absorption spectroscopy (F-AAS). Phosphonium-based ILs trihexyltetradecylphosphonium 2-(propylthio)benzoate [P{sub 66614}][PTB] and 2-(benzylthio)benzoate [P{sub 66614}][BTB] showed best extraction efficiency for copper and cadmium, respectively and zinc was extracted to a high degree by [P{sub 66614}][BTB] exclusively.

  18. The mineral base and productive capacities of metals and non-metals of Kosovo

    Energy Technology Data Exchange (ETDEWEB)

    Rizaj, M.; Beqiri, E.; McBow, I.; O' Brien, E.Z.; Kongoli, F. [University of Prishtina, Prishtina (Kosovo)

    2008-08-15

    All historical periods of Kosovo - Ilirik, Roman, Medieval, Turkish, and former Yugoslavian - are linked with the intensive development of mining and metallurgy. This activity influenced and still is influencing the overall position of Kosovo as a country. For example, according to a 2006 World Bank report as well as other studies, Kosovo has potential lignite resources (geological reserves) of about 1.5 billion tonnes, which are ranked fifth in the world in importance. Other significant Kosovan mineral resources include lead, zinc, gold, silver, bauxite, and uranium, and rare metals accompanying those minerals, including indium, cadmium, thallium, gallium, and bismuth. These rare metals are of particular importance in developing advanced industrial technologies. Kosovo also has reserves of high-quality non-metals, including magnesite, quartz grit, bentonite, argil, talc, and asbestos. No database exists for these non-metal reserves, and further research and studies are needed.

  19. The mineral base and productive capacities of metals and non-metals of Kosovo

    Science.gov (United States)

    Rizaj, M.; Beqiri, E.; McBow, I.; O'Brien, E. Z.; Kongoli, F.

    2008-08-01

    All historical periods of Kosovo—Ilirik, Roman, Medieval, Turkish, and former Yugoslavian—are linked with the intensive development of mining and metallurgy. This activity influenced and still is influencing the overall position of Kosovo as a country. For example, according to a 2006 World Bank report as well as other studies, Kosovo has potential lignite resources (geological reserves) of about 1.5 billion tonnes, which are ranked fifth in the world in importance. Other significant Kosovan mineral resources include lead, zinc, gold, silver, bauxite, and uranium, and rare metals accompanying those minerals, including indium, cadmium, thallium, gallium, and bismuth. These rare metals are of particular importance in developing advanced industrial technologies. Kosovo also has reserves of high-quality non-metals, including magnesite, quartz grit, bentonite, argil, talc, and asbestos. No database exists for these non-metal reserves, and further research and studies are needed.

  20. Defining a metal-based waste form for IFR pyroprocessing wastes

    International Nuclear Information System (INIS)

    McDeavitt, S.M.; Park, J.Y.; Ackerman, J.P.

    1994-01-01

    Pyrochemical electrorefining to recover actinides from metal nuclear fuel is a key element of the Integral Fast Reactor (IFR) fuel cycle. The process separates the radioactive fission products from the long-lived actinides in a molten LiCl-KCl salt, and it generates a lower waste volume with significantly less long-term toxicity as compared to spent nuclear fuel. The process waste forms include a mineral-based waste form that will contain fission products removed from an electrolyte salt and a metal-based waste form that will contain metallic fission products and the fuel cladding and process materials. Two concepts for the metal-based waste form are being investigated: (1) encapsulating the metal constituents in a Cu-Al alloy and (2) alloying the metal constituents into a uniform stainless steel-based waste form. Results are given from our recent studies of these two concepts

  1. Leaching of metals on stabilization of metal sludge using cement based materials.

    Science.gov (United States)

    Sophia, Carmalin A; Swaminathan, K

    2005-01-01

    Toxicity characteristic leaching procedure(TCLP) of zinc plating sludge was carried out to assess the leaching potential of the sludge and the leachates were analyzed for heavy metals. The concentration of zinc, chromium, and lead in the leachate were 371.5 mg/L, 1.95 mg/L and 1.99 mg/L respectively. Solidification of zinc sludge was carried out using four different binder systems consisting of cement mortar, fly ash, clay and lime and cured for 28 d. The ratio of sludge added varied from 60% to 80% by volume. The solidified products were tested for metal fixing efficiency and physical strength. It was observed that the volume of sludge added that resulted in maximum metal stabilization was 60% for all the combinations, above which the metal fixation efficiency decreased resulting in high values of zinc in the leachate. Addition of 5% sodium silicate enhanced the chemical fixation of metals in all the binder systems. Among the four fixing agents studied, mixture of fly ash: lime, and cement mortar: lime stabilized zinc and other metals in the sludge effectively than other combinations. Addition of lime increased the stabilization of zinc whereas cement mortar increased the strength of the solidified product.

  2. Selective extraction and detection of noble metal based on ionic ...

    Indian Academy of Sciences (India)

    With the dramatic increase in economic growth, noble metals have been extensively utilized for wide range of industries and economic activities. Gold is one of the noble metals, which used in various applications because of its unique properties. However, various reports have mentioned that gold species may cause an ...

  3. Metal Phosphides and Phosphates-based Electrodes for Electrochemical Supercapacitors.

    Science.gov (United States)

    Li, Xin; Elshahawy, Abdelnaby M; Guan, Cao; Wang, John

    2017-10-01

    Phosphorus compounds, such as metal phosphides and phosphates have shown excellent performances and great potential in electrochemical energy storage, which are demonstrated by research works published in recent years. Some of these metal phosphides and phosphates and their hybrids compare favorably with transition metal oxides/hydroxides, which have been studied extensively as a class of electrode materials for supercapacitor applications, where they have limitations in terms of electrical and ion conductivity and device stability. To be specific, metal phosphides have both metalloid characteristics and good electric conductivity. For metal phosphates, the open-framework structures with large channels and cavities endow them with good ion conductivity and charge storage capacity. In this review, we present the recent progress on metal phosphides and phosphates, by focusing on their advantages/disadvantages and potential applications as a new class of electrode materials in supercapacitors. The synthesis methods to prepare these metal phosphides/phosphates are looked into, together with the scientific insights involved, as they strongly affect the electrochemical energy storage performance. Particular attentions are paid to those hybrid-type materials, where strong synergistic effects exist. In the summary, the future perspectives and challenges for the metal phosphides, phosphates and hybrid-types are proposed and discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    Science.gov (United States)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  5. Applications of Open Source GMAW-Based Metal 3-D Printing

    OpenAIRE

    Yuenyong Nilsiam; Paul G. Sanders; Joshua M. Pearce

    2018-01-01

    The metal 3-D printing market is currently dominated by high-end applications, which make it inaccessible for small and medium enterprises, fab labs, and individual makers who are interested in the ability to prototype and additively manufacture final products in metal. Recent progress led to low-cost open-source metal 3-D printers using a gas metal arc welding (GMAW)-based print head. This reduced the cost of metal 3-D printers into the range of desktop prosumer polymer 3-D printers. Consequ...

  6. Removal of metal cations from wastewater using recycled wool-based non-woven material

    Directory of Open Access Journals (Sweden)

    MAJA RADETIC

    2007-06-01

    Full Text Available In this study, the effect of low-temperature air plasma, biopolymer chitosan and hydrogen peroxide treatment of recycled wool-based non-woven material on metal cation uptake was investigated. Recycled wool-based material either as an untreated or modified material showed ability to bind all investigated metal cations in the following order: Pb2+>Cu2+>Zn2+>Co2+. Material performed good selectivity due to distinct sorption rates of studied metal cations.

  7. Porous silicon based anode material formed using metal reduction

    Science.gov (United States)

    Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

    2015-09-22

    A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

  8. Gas metal arc welding in refurbishment of cobalt base superalloys

    Science.gov (United States)

    Shahriary, M. S.; Miladi Gorji, Y.; Kolagar, A. M.

    2017-01-01

    Refurbishments of superalloys which are used in manufacturing gas turbine hot components usually consists of removing cracks and other defects by blending and then repair welding in order to reconstruct damaged area. In this study, the effects of welding parameters on repair of FSX-414 superalloy, as the most applicable cobalt base superalloy in order to manufacture gas turbine nozzles, by use of Gas Metal Arc Welding (GMAW) technic were investigated. Results then were compared by Gas Tungsten Arc Welding (GTAW). Metallographic and SEM studies of the microstructure of the weld and HAZ showed that there are no noticeable defects in the microstructure by use of GMAW. Also, chemical analysis and morphologies of carbide in both methods are similar. Hardness profile of the GM AW structure then also compared with GTAW and no noticeable difference was observed between the profiles. Also, proper tensile properties, compared with GTAW, can be achieved by use of optimum parameters that can be obtained by examining the current and welding speed. Tensile properties of optimized condition of the GMAW then were compared with GTAW. It was seen that the room and high temperature tensile properties of the GMAW structure is very similar and results confirmed that changing the technic did not have any significant influence on the properties.

  9. Friction and wear of some ferrous-base metallic glasses

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1984-01-01

    Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminium oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

  10. Laser assisted anticancer activity of benzimidazole based metal organic nanoparticles.

    Science.gov (United States)

    Praveen, P A; Ramesh Babu, R; Balaji, P; Murugadas, A; Akbarsha, M A

    2018-03-01

    Recent studies showed that the photothermal therapy can be effectively used for the targeted cancerous cells destruction. Hence, in the present study, benzimidazole based metal organic complex nanoparticles, dichloro cobalt(II) bis-benzimidazole (Co-BMZ) and dichloro copper(II) bis-benzimidazole (Cu-BMZ), were synthesized by reprecipitation method and their anti-cancer activity by means of photothermal effect has been studied. Transmission electron microscopy analysis shows that the particle size of Cu-BMZ is ∼100 nm and Co-BMZ is in the range between 100 and 400 nm. Zeta potential analysis ensures the stability of the synthesized nanoparticles. It is found that the nonlinear absorption of the nanoparticles increases with increase in laser power intensity. Phototoxicity of human lung cancer (A549) and the normal mouse embryonic fibroblast (NIH-3T3) cells was studied using a 650 nm laser. Even though both the cell lines were affected by laser irradiation, A549 cells show higher cell destruction and lower IC 50 values than the normal cells. Docking studies were used to analyse the interaction site and the results showed that the Cu-BMZ molecules have higher dock score than the Co-BMZ molecules. The obtained results indicate that Cu-BMZ samples have lesser particle size, higher nonlinear absorption and higher interaction energy than the Co-BMZ samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Milling of Nanoparticles Reinforced Al-Based Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Alokesh Pramanik

    2018-03-01

    Full Text Available This study investigated the face milling of nanoparticles reinforced Al-based metal matrix composites (nano-MMCs using a single insert milling tool. The effects of feed and speed on machined surfaces in terms of surface roughness, surface profile, surface appearance, chip surface, chip ratio, machining forces, and force signals were analyzed. It was found that surface roughness of machined surfaces increased with the increase of feed up to the speed of 60 mm/min. However, at the higher speed (100–140 mm/min, the variation of surface roughness was minor with the increase of feed. The machined surfaces contained the marks of cutting tools, lobes of material flow in layers, pits and craters. The chip ratio increased with the increase of feed at all speeds. The top chip surfaces were full of wrinkles in all cases, though the bottom surfaces carried the evidence of friction, adhesion, and deformed material layers. The effect of feed on machining forces was evident at all speeds. The machining speed was found not to affect machining forces noticeably at a lower feed, but those decreased with the increase of speed for the high feed scenario.

  12. Luminescent multifunctional lanthanides-based metal-organic frameworks.

    Science.gov (United States)

    Rocha, João; Carlos, Luís D; Paz, Filipe A Almeida; Ananias, Duarte

    2011-02-01

    Metal-organic frameworks based on trivalent lanthanides (LnMOFs) are a very promising class of materials for addressing the challenges in engineering of luminescent centres. Lanthanide-bearing phosphors find numerous applications in lighting, optical communications, photonics and biomedical devices. In this critical review we discuss the potential of LnMOFs as multifunctional systems, which combine light emission with properties such as microporosity, magnetism, chirality, molecule and ion sensing, catalysis and activity as multimodal imaging contrast agents. We argue that these materials present a unique chance of observing synergy between several of these properties, such as the coupling between photoluminescence and magnetism. Moreover, an integrated approach towards the design of efficient, stable, cheap, environmentally-friendly and multifunctional luminescent LnMOFs is still missing. Although research into LnMOFs is at its early stage and much basic knowledge is still needed, the field is ripe for new ideas, which will enable sensor devices and photonic prototypes to become a commercial reality (81 references).

  13. A Fundamental Approach to Developing Aluminium based Bulk Amorphous Alloys based on Stable Liquid Metal Structures and Electronic Equilibrium - 154041

    Science.gov (United States)

    2017-03-28

    AFRL-AFOSR-JP-TR-2017-0027 A Fundamental Approach to Developing Aluminium -based Bulk Amorphous Alloys based on Stable Liquid-Metal Structures and...to 16 Dec 2016 4.  TITLE AND SUBTITLE A Fundamental Approach to Developing Aluminium -based Bulk Amorphous Alloys based on Stable Liquid-Metal...Air Force Research Laboratory for accurately predicting compositions of new amorphous alloys specifically based on aluminium with properties superior

  14. Bond strength of self-adhesive resin cement to base metal alloys having different surface treatments

    Directory of Open Access Journals (Sweden)

    Farhad Shafiei

    2018-01-01

    Conclusion: Based on the results, sandblasting improves the shear bond strength of self-etch and self-adhesive resin cement to base metal alloys. The best results can be achieved with a combination of sandblasting and metal primers. The performance of resin cement depends on to their chemical composition, not to the type of system.

  15. Nano-structured noble metal catalysts based on hexametallate architecture for the reforming of hydrocarbon fuels

    Science.gov (United States)

    Gardner, Todd H.

    2015-09-15

    Nano-structured noble metal catalysts based on hexametallate lattices, of a spinel block type, and which are resistant to carbon deposition and metal sulfide formation are provided. The catalysts are designed for the reforming of hydrocarbon fuels to synthesis gas. The hexametallate lattices are doped with noble metals (Au, Pt, Rh, Ru) which are atomically dispersed as isolated sites throughout the lattice and take the place of hexametallate metal ions such as Cr, Ga, In, and/or Nb. Mirror cations in the crystal lattice are selected from alkali metals, alkaline earth metals, and the lanthanide metals, so as to reduce the acidity of the catalyst crystal lattice and enhance the desorption of carbon deposit forming moieties such as aromatics. The catalysts can be used at temperatures as high as 1000.degree. C. and pressures up to 30 atmospheres. A method for producing these catalysts and applications of their use also is provided.

  16. Terahertz wave manipulation with metamaterials based on metal and graphene

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    2013-01-01

    for active and passive materials and devices. Metamaterials, metal-dielectric artificial composites, propose wide possibilities for achieving unconventional electromagnetic properties, not found in nature. Moreover, metamaterials constructed of graphene, a monolayer of carbon atoms, allow for tunable...

  17. High pressure and microwave based synthesis of transition metal pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Pobel, Roman Rupert

    2016-04-11

    The goal of this thesis was to explore the possibilities of synthetic methods that are not very common in current transition metal pnictide research. The substitution of the Ca-site in CaFe{sub 2}As{sub 2} with rare earth elements such as Pr the has been reported to induce superconductivity. However, some inconsistencies in the data suggested a non-intrinsic origin of the observed diamagnetic signal. Furthermore a solubility limit of 13% was found when prepared in an electrical furnace thus leaving a huge part of the physical phase diagram inaccessible. A high pressure/high temperature synthesis was developed to allow access to the whole doping range and an in-depth characterization of this compound was carried out. During the experiments concerning the high pressure synthesis of Ca{sub 1-x}Pr{sub x}Fe{sub 2}As{sub 2} the new ternary iron arsenide CaFe{sub 5}As{sub 3} was identified and classified as a member of the Ca{sub n(n+1)/2}(Fe{sub 1-x}M{sub x}){sub (2+3n)}M'{sub n(n-1)/2}As{sub (n+1)(n+2)/2} (n = 1-3; M =Nb, Pd, Pt; M' = □, Pd, Pt) family. The complete solid solution Ca{sub 1-x}Pr{sub x}Fe{sub 5}As{sub 3} (O ≤ x ≤ 1) was prepared and physically characterized. Furthermore, several useful techniques were developed to aid in future high pressure based investigations of transition metal pnictides. The second part of this thesis concerns a completely different, but equally promising synthetic approach. Microwave based synthesis is a well-established technique in many solution based fields, such as organic, medicinal or nano chemistry. For solid state and materials research several parameters and particularities have to be considered. But when successful, it allows for the reduction of reaction time by several orders of magnitude. It has very rarely been applied in the preparation of pnictides and on1y once in the context of pnictide superconductor research. The possibilities of this method were explored and employed in the preparation of several

  18. A plasmonic modulator based on metal-insulator-metal waveguide with barium titanate core

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2013-01-01

    We design a plasmonic modulator which can be utilized as a compact active device in photonic integrated circuits. The active material, barium titanate (BaTiO3), is sandwiched between metal plates and changes its refractive index under applied voltage. Some degree of switching of ferroelectric...

  19. Carbon-Based Metal-Free Catalysts for Electrocatalysis beyond the ORR.

    Science.gov (United States)

    Hu, Chuangang; Dai, Liming

    2016-09-19

    Besides their use in fuel cells for energy conversion through the oxygen reduction reaction (ORR), carbon-based metal-free catalysts have also been demonstrated to be promising alternatives to noble-metal/metal oxide catalysts for the oxygen evolution reaction (OER) in metal-air batteries for energy storage and for the splitting of water to produce hydrogen fuels through the hydrogen evolution reaction (HER). This Review focuses on recent progress in the development of carbon-based metal-free catalysts for the OER and HER, along with challenges and perspectives in the emerging field of metal-free electrocatalysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

    Gao, Changhua (Michael)

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

  1. Metallated porphyrin based porous organic polymers as efficient electrocatalysts

    Science.gov (United States)

    Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

    2015-10-01

    Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm-2) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm-2). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e- pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system.Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both

  2. Review of Ni-Cu Based Front Side Metallization for c-Si Solar Cells

    Directory of Open Access Journals (Sweden)

    Mehul C. Raval

    2013-01-01

    Full Text Available Given the high percentage of metal cost in cell processing and concerns due to increasing Ag prices, alternative metallization schemes are being considered. Ni-Cu based front side metallization offers potential advantages of finer grid lines, lower series resistance, and reduced costs. A brief overview of various front side patterning techniques is presented. Subsequently, working principle of various plating techniques is discussed. For electroless plated Ni seed layer, fill factor values nearing 80% and efficiencies close to 17.5% have been demonstrated, while for Light Induced Plating deposited layers, an efficiency of 19.2% has been reported. Various methods for qualifying adhesion and long term stability of metal stack are discussed. Adhesion strengths in the range of 1–2.7 N/mm have been obtained for Ni-Cu contacts tabbed with conventional soldering process. Given the significance of metallization properties, different methods for characterization are outlined. The problem of background plating for Ni-Cu based metallization along with the various methods for characterization is summarized. An economic evaluation of front side metallization indicates process cost saving of more than 50% with Ni-Cu-Sn based layers. Recent successful commercialization and demonstration of Ni-Cu based metallization on industrial scale indicate a potential major role of Ni-Cu based contacts in near future.

  3. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, Bartley B. [Univ. of California, Berkeley, CA (United States)

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF2, ThO2, YDT(0.85ThO2-0.15YO1.5), and LDT(0.85ThO2- 0.15LaO1.5) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  4. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF[sub 2], ThO[sub 2], YDT(0.85ThO[sub 2]-0.15YO[sub 1.5]), and LDT(0.85ThO[sub 2]- 0.15LaO[sub 1.5]) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  5. Gallium-Based Room-Temperature Liquid Metals: Actuation and Manipulation of Droplets and Flows

    Directory of Open Access Journals (Sweden)

    Leily Majidi

    2017-08-01

    Full Text Available Gallium-based room-temperature liquid metals possess extremely valuable properties, such as low toxicity, low vapor pressure, and high thermal and electrical conductivity enabling them to become suitable substitutes for mercury and beyond in wide range of applications. When exposed to air, a native oxide layer forms on the surface of gallium-based liquid metals which mechanically stabilizes the liquid. By removing or reconstructing the oxide skin, shape and state of liquid metal droplets and flows can be manipulated/actuated desirably. This can occur manually or in the presence/absence of a magnetic/electric field. These methods lead to numerous useful applications such as soft electronics, reconfigurable devices, and soft robots. In this mini-review, we summarize the most recent progresses achieved on liquid metal droplet generation and actuation of gallium-based liquid metals with/without an external force.

  6. In situ X-ray absorption spectroscopy of transition metal based water oxidation catalysts

    NARCIS (Netherlands)

    van Oversteeg, Christina H M|info:eu-repo/dai/nl/413490483; Doan, Hoang Q; de Groot, Frank M F|info:eu-repo/dai/nl/08747610X; Cuk, Tanja

    2016-01-01

    X-ray absorption studies of the geometric and electronic structure of primarily heterogeneous Co, Ni, and Mn based water oxidation catalysts are reviewed. The X-ray absorption near edge and extended X-ray absorption fine structure studies of the metal K-edge, characterize the metal oxidation state,

  7. Gamma Prime Morphology and Creep Properties of Nickel Based Superalloys With Platinum Group Metal Additions (Preprint)

    Science.gov (United States)

    2008-04-01

    Cobalt on the Tensile and Stress Rupture Properties of the Nickel-Base Superalloy MAR-M247,” Metallurgical Transactions A, 13 (A) (1982), 1767-1774.           10 ...AFRL-RX-WP-TP-2008-4320 GAMMA PRIME MORPHOLOGY AND CREEP PROPERTIES OF NICKEL BASED SUPERALLOYS WITH PLATINUM GROUP METAL ADDITIONS...AND SUBTITLE GAMMA PRIME MORPHOLOGY AND CREEP PROPERTIES OF NICKEL BASED SUPERALLOYS WITH PLATINUM GROUP METAL ADDITIONS (PREPRINT) 5a.

  8. High-temperature performance of a new nickel-based filler metal for power generation application

    Energy Technology Data Exchange (ETDEWEB)

    Shingledecker, J.; Coleman, K. [Electric Power Research Institute, Charlotte, NC (United States); Siefert, J.; Tanzosh, J. [Babcok and Wilcox Research Center, Barberton, OH (United States); Newell, W. [Euroweld, Mooresville, NC (United States)

    2010-07-01

    A new nickel-based weld filler metal, EPRI P87, has been developed as a superior alternative to ERNiCr-3 for use in dissimilar metal welds (DMW) between ferritic and austenitic materials. EPRI P87 has a low coefficient of thermal expansion more closely matching alloys such as Grade 91 and 92 than other available filler metals. Additionally, the size of the carbon denuded region adjacent to the weld in the heat-affected-zone is minimized/eliminated by proper control of weld metal composition. In this work the high-temperature mechanical behavior of DMWs utilizing EPRI P87 (GTAW and GMAW processes) was characterized through tensile and long-term creep-rupture testing. Microstructure analysis was also conducted on tested specimens to evaluate the HAZ regions and failure modes. Performance of the weld metal and welded joints is discussed and compared with ERNiCr-3 and typical 9%Cr-MoV filler metals. (orig.)

  9. Design of Cu8Zr5-based bulk metallic glasses

    DEFF Research Database (Denmark)

    Yang, L.; Xia, J.H.; Wang, Q.

    2006-01-01

    Basic polyhedral clusters have been derived from intermetallic compounds at near-eutectic composition by considering a dense packing and random arrangement of atoms at shell sites. Using such building units, bulk metallic glasses can be formed. This strategy was verified in the Cu-Zr binary syste...

  10. Thin metal films in resistivity-based chemical sensing

    Czech Academy of Sciences Publication Activity Database

    Podešva, Pavel; Foret, František

    2013-01-01

    Roč. 9, č. 4 (2013), s. 642-652 ISSN 1573-4110 R&D Projects: GA ČR(CZ) GAP301/11/2055 Institutional support: RVO:68081715 Keywords : voltohmmetric sensing * chemiresistor * thin metal film * gas sensing Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.194, year: 2013

  11. Transition metal-free, base-promoted hydroalkoxylation: Synthesis ...

    Indian Academy of Sciences (India)

    Abstract. An efficient,transition metal-free method to synthesize substituted imidazo[2,1-c][1,4]oxazine derivatives via hydroalkoxylation of 1,5-alkynyl alcohol has been described. The reaction ... Muthusubramanian1. Department of Organic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India ...

  12. Synthesis, spectral characterization of Schiff base transition metal ...

    Indian Academy of Sciences (India)

    The UV-Vis, magnetic susceptibility and ESR spectral data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The redox behaviour of copper and vanadyl complexes was studied by cyclic voltammetry. Antimicrobial screening tests ...

  13. Systems and Methods for Fabricating Structures Including Metallic Glass-Based Materials Using Low Pressure Casting

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Kennett, Andrew (Inventor)

    2018-01-01

    Systems and methods to fabricate objects including metallic glass-based materials using low-pressure casting techniques are described. In one embodiment, a method of fabricating an object that includes a metallic glass-based material includes: introducing molten alloy into a mold cavity defined by a mold using a low enough pressure such that the molten alloy does not conform to features of the mold cavity that are smaller than 100 microns; and cooling the molten alloy such that it solidifies, the solid including a metallic glass-based material.

  14. Carbon based secondary compounds do not provide protection against heavy metal road pollutants in epiphytic macrolichens.

    Science.gov (United States)

    Gauslaa, Yngvar; Yemets, Olena A; Asplund, Johan; Solhaug, Knut Asbjørn

    2016-01-15

    Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to search for relationships between concentrations of heavy metals and CBSCs along a gradient in heavy metal pollutants. Viability parameters and concentrations of 21 elements including nutrients and heavy metals in these lichen samples were reported in a separate paper. Medullary CBSCs in fruticose lichens (Ramalina farinacea, Usnea dasypoga) were reduced in the most polluted sites, but not in foliose ones (Parmelia sulcata, Lobaria pulmonaria), whereas cortical CBSC did not change with distance from the road in any species. Strong positive correlations only occurred between the major medullary compound stictic acid present in L. pulmonaria and most heavy metals, consistent with a chelating role of stictic acid, but not of other studied CBSCs or in other species. However, heavy metal chelating did not protect L. pulmonaria against damage because this species experienced the strongest reduction in viability in the polluted sites. CBSCs with an accumulation potential for heavy metals should be quantified in lichen biomonitoring studies of heavy metals because they, like stictic acid, could overshadow pollutant inputs in some species rendering biomonitoring data less useful. In the two fruticose lichen species, CBSCs decreased with increasing heavy metal concentration, probably because heavy metal exposure impaired secondary metabolism. Thus, we found no support for a heavy metal protection role of any CBSCs in studied epiphytic lichens. No intraspecific relationships occurred between CBSCs versus N or C/N-ratio. Interspecifically, medullary CBSCs decreased and cortical CBSCs increased with increasing C/N-ratio. Copyright © 2015

  15. Influence of S. mutans on base-metal dental casting alloy toxicity.

    Science.gov (United States)

    McGinley, E L; Dowling, A H; Moran, G P; Fleming, G J P

    2013-01-01

    We have highlighted that exposure of base-metal dental casting alloys to the acidogenic bacterium Streptococcus mutans significantly increases cellular toxicity following exposure to immortalized human TR146 oral keratinocytes. With Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), S. mutans-treated nickel-based (Ni-based) and cobalt-chromium-based (Co-Cr-based) dental casting alloys were shown to leach elevated levels of metal ions compared with untreated dental casting alloys. We targeted several biological parameters: cell morphology, viable cell counts, cell metabolic activity, cell toxicity, and inflammatory cytokine expression. S. mutans-treated dental casting alloys disrupted cell morphology, elicited significantly decreased viable cell counts (p dental casting alloys induced elevated levels of cellular toxicity compared with S. mutans-treated Co-Cr-based dental casting alloys. While our findings indicated that the exacerbated release of metal ions from S. mutans-treated base-metal dental casting alloys was the likely result of the pH reduction during S. mutans growth, the exact nature of mechanisms leading to accelerated dissolution of alloy-discs is not yet fully understood. Given the predominance of S. mutans oral carriage and the exacerbated cytotoxicity observed in TR146 cells following exposure to S. mutans-treated base-metal dental casting alloys, the implications for the long-term stability of base-metal dental restorations in the oral cavity are a cause for concern.

  16. Poultry litter-based activated carbon for removing heavy metal ions in water.

    Science.gov (United States)

    Guo, Mingxin; Qiu, Guannan; Song, Weiping

    2010-02-01

    Utilization of poultry litter as a precursor material to manufacture activated carbon for treating heavy metal-contaminated water is a value-added strategy for recycling the organic waste. Batch adsorption experiments were conducted to investigate kinetics, isotherms, and capacity of poultry litter-based activated carbon for removing heavy metal ions in water. It was revealed that poultry litter-based activated carbon possessed significantly higher adsorption affinity and capacity for heavy metals than commercial activated carbons derived from bituminous coal and coconut shell. Adsorption of metal ions onto poultry litter-based carbon was rapid and followed Sigmoidal Chapman patterns as a function of contact time. Adsorption isotherms could be described by different models such as Langmuir and Freundlich equations, depending on the metal species and the coexistence of other metal ions. Potentially 404 mmol of Cu2+, 945 mmol of Pb2+, 236 mmol of Zn2+, and 250-300 mmol of Cd2+ would be adsorbed per kg of poultry litter-derived activated carbon. Releases of nutrients and metal ions from litter-derived carbon did not pose secondary water contamination risks. The study suggests that poultry litter can be utilized as a precursor material for economically manufacturing granular activated carbon that is to be used in wastewater treatment for removing heavy metals.

  17. Accumulation of Heavy Metals in Soil and Kiwifruit of Planting Base in Western Hunan Province, China

    Directory of Open Access Journals (Sweden)

    WANG Ren-cai

    2017-05-01

    Full Text Available The heavy metals accumulation in soil and kiwi fruit plant in Western Hunan Province main kiwifruit planting base were analyzed, such as As, Pb, Hg, Cd, Cr. The results showed that the accumulation of heavy metals in soil of 6 kiwifruit planting areas were not obvious. The contents of heavy metals in most of areas of Western Hunan Province were below the national standard, except one area where the soil contents of cadmium (4.900 mg·kg-1, mercury (0.634 mg·kg-1were exceeded. At the same time, the comprehensive pollution index of heavy metals was less than 0.7 in these areas. There were 5 bases with no pollution of heavy metal, all which the kiwifruit could be safely produced in line with the requirements of the green kiwifruit planting base soil standards. At these areas, the contents of various heavy metals(except cadmium and mercurywere small in the branches and leaves of kiwifruit; kiwifruit had a very well capacity to absorb the cadmium when the cadmium content of its branches reached 12.73%. The heavy metal contents of the kiwifruit in the 6 regions, which belonging to the pollutionfree green fruits, were below or far lower than the national standard. According to the comprehensive analysis, the soil condition of the main cultivated land in Western Hunan Province was good, and the fruit had no heavy metal residues.

  18. Evaluating Heavy Metal Stress Levels in Rice Based on Remote Sensing Phenology

    Directory of Open Access Journals (Sweden)

    Tianjiao Liu

    2018-03-01

    Full Text Available Heavy metal pollution of croplands is a major environmental problem worldwide. Methods for accurately and quickly monitoring heavy metal stress have important practical significance. Many studies have explored heavy metal stress in rice in relation to physiological function or physiological factors, but few studies have considered phenology, which can be sensitive to heavy metal stress. In this study, we used an integrated Normalized Difference Vegetation Index (NDVI time-series image set to extract remote sensing phenology. A phenological indicator relatively sensitive to heavy metal stress was chosen from the obtained phenological periods and phenological parameters. The Dry Weight of Roots (WRT, which directly affected by heavy metal stress, was simulated by the World Food Study (WOFOST model; then, a feature space based on the phenological indicator and WRT was established for monitoring heavy metal stress. The results indicated that the feature space can distinguish the heavy metal stress levels in rice, with accuracy greater than 95% for distinguishing the severe stress level. This finding provides scientific evidence for combining rice phenology and physiological characteristics in time and space, and the method is useful to monitor heavy metal stress in rice.

  19. Evaluating Heavy Metal Stress Levels in Rice Based on Remote Sensing Phenology.

    Science.gov (United States)

    Liu, Tianjiao; Liu, Xiangnan; Liu, Meiling; Wu, Ling

    2018-03-14

    Heavy metal pollution of croplands is a major environmental problem worldwide. Methods for accurately and quickly monitoring heavy metal stress have important practical significance. Many studies have explored heavy metal stress in rice in relation to physiological function or physiological factors, but few studies have considered phenology, which can be sensitive to heavy metal stress. In this study, we used an integrated Normalized Difference Vegetation Index (NDVI) time-series image set to extract remote sensing phenology. A phenological indicator relatively sensitive to heavy metal stress was chosen from the obtained phenological periods and phenological parameters. The Dry Weight of Roots (WRT), which directly affected by heavy metal stress, was simulated by the World Food Study (WOFOST) model; then, a feature space based on the phenological indicator and WRT was established for monitoring heavy metal stress. The results indicated that the feature space can distinguish the heavy metal stress levels in rice, with accuracy greater than 95% for distinguishing the severe stress level. This finding provides scientific evidence for combining rice phenology and physiological characteristics in time and space, and the method is useful to monitor heavy metal stress in rice.

  20. Wear behaviour of Zr-based in situ bulk metallic glass matrix ...

    Indian Academy of Sciences (India)

    based bulk metallic glass (BMG) and its in situ BMG matrix composites with diameter of 3 mm were fabricated by conventional Cu-mould casting method and ... The composites showed lower friction coefficient and wear rate than the pure BMG.

  1. PHYSICAL BASES OF SYSTEMS CREATION FOR MAGNETIC-IMPULSIVE ATTRACTION OF THIN-WALLED SHEET METALS

    Directory of Open Access Journals (Sweden)

    Y. Batygin

    2009-01-01

    Full Text Available The work is dedicated to the physical base of systems creating for the thin-walled sheet metals magnetic pulse attraction. Some practical realization models of the author’s suggestions are represented.

  2. Reliability Modeling Development and Its Applications for Ceramic Capacitors with Base-Metal Electrodes (BMEs)

    Science.gov (United States)

    Liu, Donhang

    2014-01-01

    This presentation includes a summary of NEPP-funded deliverables for the Base-Metal Electrodes (BMEs) capacitor task, development of a general reliability model for BME capacitors, and a summary and future work.

  3. Development of Low Density CaMg-A1-Based Bulk Metallic Glasses (Preprint)

    National Research Council Canada - National Science Library

    Senkov, O. N; Scott, J. M; Miracle, D. B

    2006-01-01

    Low density Ca-Mg-Al-based bulk metallic glasses containing additionally Cu and Zn, were produced by a copper mold casting method as wedge-shaped samples with thicknesses varying from 0.5 mm to 10 rom...

  4. Precipitation of Niobium Boride Phases at the Base Metal/Weld Metal Interface in Dissimilar Weld Joints

    Science.gov (United States)

    Výrostková, Anna; Kepič, Ján; Homolová, Viera; Falat, Ladislav

    2015-07-01

    In this work, the analysis of failure mechanism in the heat affected zone is described in dissimilar weld joints between advanced martensitic steel T92 and Ni-base weld metal. The joints were treated with two different post-weld heat treatments and tested. For the creep, tensile, and Charpy impact tests, the samples with interfacially located notch were used. Moreover long term aging at 625 °C was applied before the tensile and notch toughness tests. Decohesion fractures ran along carbides at the T92 BM/WM interfaces in case of the modified PWHT, whereas type IV cracking was the prevailing failure mechanism after the classical PWHT in the creep test. In the notch tensile and Charpy impact tests, with the notch at T92 base metal/weld metal interface, fractures ran along the interface with a hard phase on the fracture surface along with the ductile dimple and brittle quasi-cleavage fracture. The phase identified as niobium boride (either NbB and/or Nb3B2) was produced during welding at the end of the solidification process. It was found in the welds regardless of the post-weld heat treatment and long-term aging.

  5. Comparison of metals extractability from Al/Fe-based drinking water treatment residuals.

    Science.gov (United States)

    Wang, Changhui; Bai, Leilei; Pei, Yuansheng; Wendling, Laura A

    2014-12-01

    Recycling of drinking water treatment residuals (WTRs) as environment amendments has attracted substantial interest due to their productive reuse concomitant with waste minimization. In the present study, the extractability of metals within six Al/Fe-hydroxide-comprised WTRs collected throughout China was investigated using fractionation, in vitro digestion and the toxicity characteristic leaching procedure (TCLP). The results suggested that the major components and structure of the WTRs investigated were similar. The WTRs were enriched in Al, Fe, Ca, and Mg, also contained varying quantities of As, Ba, Be, Cd, Co, Cr, Cu, K, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn, but Ag, Hg, Sb, and Se were not detected. Most of the metals within the WTRs were largely non-extractable using the European Community Bureau of Reference (BCR) procedure, but many metals exhibited high bioaccessibility based on in vitro digestion. However, the WTRs could be classified as non-hazardous according to the TCLP assessment method used by the US Environmental Protection Agency (USEPA). Further analysis showed the communication factor, which is calculated as the ratio of total extractable metal by BCR procedure to the total metal, for most metals in the six WTRs, was similar, whereas the factor for Ba, Mn, Sr, and Zn varied substantially. Moreover, metals in the WTRs investigated had different risk assessment code. In summary, recycling of WTRs is subject to regulation based on assessment of risk due to metals prior to practical application.

  6. Permutation entropy based speckle analysis in metal cutting

    Science.gov (United States)

    Nair, Usha; Krishna, Bindu M.; Namboothiri, V. N. N.; Nampoori, V. P. N.

    2008-08-01

    Machine tool chatter is an unfavorable phenomenon during metal cutting, which results in heavy vibration of cutting tool. With increase in depth of cut the cutting regime changes from chatter- free cutting to one with chatter. In this paper, we propose the use of permutation entropy (PE), a conceptually simple and computationally fast measure to detect the onset of chatter from the time series generated using laser speckle pattern recorded using Charge Couple Device (CCD) camera. Laser speckle is an interference pattern produced by light reflected or scattered from different parts of the illuminated surface. It is the superposition of many wave fronts with random phases, scattered from different parts of the rough surface. If a speckle pattern is produced by coherent light incident on a rough surface, then surely the speckle pattern, or at least the statistics of the speckle pattern, must depend upon the detailed surface properties. Therefore we propose PE as an ideal measure, which can efficiently distinguish regular and complex nature of any signal, to extract information about the roughness of the reflecting surface. In the present study two work pieces, one taper cut and one step cut are machined to form cylindrical pieces, by continuously varying the depth of cut. As the depth of cut increases the surface finish is expected to deteriorate, mainly due to the onset of chatter vibrations. To analyze the surface texture characteristics, the speckle pattern is obtained by illuminating this curved surface using a collimated laser beam (5mW Diode Laser at 676nm wavelength.). The laser beam is made to incident obliquely to the curved surface of the work piece, and the speckle pattern is recorded using a CCD camera. The beam is scanned along the axis of the work-piece and the speckle pattern is recorded at different regions at constant intervals. A time series is generated from the speckle data and analyzed using PE. Permutation entropy is a complexity measure suitable

  7. Terahertz artificial material based on integrated metal-rod-array for phase sensitive fluid detection.

    Science.gov (United States)

    You, Borwen; Chen, Ching-Yu; Yu, Chin-Ping; Liu, Tze-An; Hattori, Toshiaki; Lu, Ja-Yu

    2017-04-17

    A terahertz artificial material composed of metal rod array is experimentally investigated on its transmission spectral property and successfully incorporated into microfluidics as a miniaturized terahertz waveguide with an extended optical-path-length for label-free fluidic sensing. Theoretical and experimental characterizations of terahertz transmission spectra show that the wave guidance along the metal rod array originates from the resonance of transverse-electric-polarized waves within the metal rod slits. The extended optical path length along three layers of metal-rod-array enables terahertz waves sufficiently overlapping the fluid molecules embedded among the rods, leading to strongly enhanced phase change by approximately one order of magnitude compared with the blank metal-parallel-plate waveguide. Based on the enhanced phase sensitivity, three kinds of colorless liquid analytes, namely, acetone, methanol, and ethanol, with different dipole moments are identified in situ using the metal-rod-array-based microfluidic sensor. The detection limit in molecular amounts of a liquid analyte is experimentally demonstrated to be less than 0.1 mmol, corresponding to 2.7 μmol/mm2. The phase sensitive terahertz metal-rod-array-based sensor potentially has good adaptability in lab-chip technology for various practical applications, such as industrial toxic fluid detection and medical breath inspection.

  8. The effect of recasting on bond strength between porcelain and base-metal alloys.

    Science.gov (United States)

    Madani, Azam S; Rokni, Shahin Rezaii; Mohammadi, Abolghasem; Bahrami, Mehran

    2011-04-01

    Long-term success of metal ceramic restorations depends on metal ceramic bond strength. The purpose of this study was to determine whether recasting of base-metal alloys has any effect on metal ceramic bond strength. Super Cast and Verabond base-metal alloys were used to cast 260 wax patterns. The alloy specimens were equally divided into five groups and cast as: group A 0.0%, B 25%, C 50%, D 75%, and E 100% once-cast alloy. Each group was divided into two subgroups: the first group was cast with Super Cast and the second with Verabond. In each subgroup half of the cast alloys were veneered with Vita VMK 68 and the others with Ceramco 3. Recasting decreased bond strength (p alloy. Group E with 100% new Super Cast alloy veneered with Vita VMK 68 porcelain had the highest bond strength (30.75 ± 9.58 MPa), and group B including 25% new and 75% recast Super Cast alloy veneered with the same porcelain had the lowest bond strength (21.72 ± 5.19 MPa). By adding over 50% once-cast alloy in base-metal alloys, metal-ceramic bond strength decreases significantly. © 2011 by The American College of Prosthodontists.

  9. Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

    Energy Technology Data Exchange (ETDEWEB)

    Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

    2017-02-07

    The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

  10. Recent advances in DNA-based electrochemical biosensors for heavy metal ion detection: A review.

    Science.gov (United States)

    Saidur, M R; Aziz, A R Abdul; Basirun, W J

    2017-04-15

    The presence of heavy metal in food chains due to the rapid industrialization poses a serious threat on the environment. Therefore, detection and monitoring of heavy metals contamination are gaining more attention nowadays. However, the current analytical methods (based on spectroscopy) for the detection of heavy metal contamination are often very expensive, tedious and can only be handled by trained personnel. DNA biosensors, which are based on electrochemical transduction, is a sensitive but inexpensive method of detection. The principles, sensitivity, selectivity and challenges of electrochemical biosensors are discussed in this review. This review also highlights the major advances of DNA-based electrochemical biosensors for the detection of heavy metal ions such as Hg 2+ , Ag + , Cu 2+ and Pb 2+ . Copyright © 2016 Elsevier B.V. All rights reserved.

  11. PREPARATION AND PROPERTIES OF THE COLLODIAL SOLUTION BASED ON BIOGENIC METAL NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    K. V. Liapina

    2014-12-01

    Full Text Available The aim of the work was obtaining a stable suspension based on biocompatible substances with application of biogenic metal nanoparticles encapsulated into NaCl salt matrix, as a precursor. Water-soluble complex based on different amine derivatives with antiseptic properties was selected as a liquid for salt dissolution. The solution was subjected to dispersion using ultrasonication at elevated temperature. Dispersion is accompanied by salt shell removal with simultaneous formation of an organic shell on the surfaces of metal nanoparticles that ensure their stabilization. Study of the suspension after soaking at room temperature for 100 days showed that its characteristics remain stable. A method for producing a stable colloidal solution based on nanoparticles of biogenic metal (Cu, Co, fem etc. was developed. Metal nanopowder encapsulated into salt shell was used as a precursor. It is shown that such colloidal solutions are characterized by narrow size dispersion, as well as stability to temperature impact and time factor.

  12. Vacuum spark breakdown model based on exploding metal wire phenomena

    International Nuclear Information System (INIS)

    Haaland, J.

    1984-06-01

    Spark source mass spectra (SSMS) indicates that ions are extracted from an expanding and decaying plasma. The intensity distribution shows no dependance on vaporization properties of individual elements which indicates explosive vapour formation. This seems further to be a requirement for bridging a vacuum gap. A model including plasma ejection from a superheated anode spot by a process similar to that of an exploding metal wire is proposed. The appearance of hot plasma points in low inductance vacuum sparks can then be explained as exploding micro particles ejected from a final central anode spot. The phenomenological model is compared with available experimental results from literature, but no extensive quantification is attempted

  13. Polyacrylonitrile-based carbonized fibers and metal-carbonized fiber nanocomposites for thermal transport.

    Science.gov (United States)

    Ochanda, Fredrick; Atkinson, Ariel; Fey, Edmond O; Andala, Dickson; Jones, Wayne E

    2010-12-01

    This work examines the fabrication and thermal analysis of metal-carbon composite fibers prepared via an electrospinning process. The metal-carbon composite fibers of silver, copper, gold, and nickel were prepared by electrospinning of a composite solution of polyacrylonitrile (PAN) and metal precursor followed by heat treatment in air, nitrogen to 1000 degrees C and in 6% H2, respectively. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and Scanning thermal microscopy (SThM) were applied to characterize the metal-carbon fibers. TEM analysis showed a relatively uniform, contact-free distribution of the nanoparticles on the surface of the carbon fibers with size range of 3 nm-10 nm. Thermal analysis data showed an enhancement in the thermal conductivity of the nanomaterials when compared with the model PAN-based carbonized fibers. This was attributed to the incorporation of metal nanoparticles in the fiber matrix and on the surface.

  14. The development of PC-based real time ultrasonic metal thickness inspection system

    International Nuclear Information System (INIS)

    Suhairy Sani; Mohd Hanif Md Saad; Mohamad Pauzi Ismail; Ab Razak Hamzah; Abd Nassir Ibrahim; Amri Amin Abas

    2006-01-01

    This paper discusses the development of a PC-Based Real Time Ultrasonic Thickness Measurement system (UTMS) for metallic components such as pipes, pressure vessels and metal slabs. Metal thickness measurement for these components is crucial in industrial plants with dangerous environment, such as in oil and gas industry. From the measured metal thickness, a number of deductions could be made, for example the state and the rate of corrosion propagation inside a pipe or pressure vessel, etc. One of the most widely used methods in assessing metal thickness in industry is through the use of Ultrasonic technology. The benefits of using UTMS lies in the flexibility of data analysis, which includes signal processing, feature extraction, visualization capability and intelligent diagnosis. Data can be acquired in real-time and stored for future usage and application. The system was developed as a standalone computer software using Microsoft Visual-BASIC 6. (Author)

  15. A novel wideband optical absorber based on all-metal 2D gradient nanostructures

    Science.gov (United States)

    Gong, Jianhao; Yang, Fulong; Zhang, Xiaoping

    2017-11-01

    Recently, all-metal nanostructures for perfect absorption of light have attracted much attention due to their excellent plasmonic and photonic properties, but only narrow absorption bands were obtained in previous studies. In this paper, a new kind of metallic metasurface with wideband absorption of visible light is designed, which consists only of a gold nanotriangle array on the opaque metal substrate. By combining different resonant modes in the gradual-changed triangular nanostructure, the wide absorption waveband in visible region from 378 to 626 nm is achieved with more than 90% absorptivity. We demonstrate that the absorption property of the nanostructure can be controlled by tuning the cell size and incident angle. In addition, a metallic trapezoidal grating structure is proposed which can also realize wideband light absorption. This research provides a novel strategy in designing wideband metamaterial absorbers for visible light based on all-metal nanostructures which have great potential applications in light energy harvesting and photoelectric conversion.

  16. Immobilisation of heavy metal in cement-based solidification/stabilisation: A review

    International Nuclear Information System (INIS)

    Chen, Q.Y.; Tyrer, M.; Hills, C.D.; Yang, X.M.; Carey, P.

    2009-01-01

    Heavy metal-bearing waste usually needs solidification/stabilization (s/s) prior to landfill to lower the leaching rate. Cement is the most adaptable binder currently available for the immobilisation of heavy metals. The selection of cements and operating parameters depends upon an understanding of chemistry of the system. This paper discusses interactions of heavy metals and cement phases in the solidification/stabilisation process. It provides a clarification of heavy metal effects on cement hydration. According to the decomposition rate of minerals, heavy metals accelerate the hydration of tricalcium silicate (C 3 S) and Portland cement, although they retard the precipitation of portlandite due to the reduction of pH resulted from hydrolyses of heavy metal ions. The chemical mechanism relevant to the accelerating effect of heavy metals is considered to be H + attacks on cement phases and the precipitation of calcium heavy metal double hydroxides, which consumes calcium ions and then promotes the decomposition of C 3 S. In this work, molecular models of calcium silicate hydrate gel are presented based on the examination of 29 Si solid-state magic angle spinning/nuclear magnetic resonance (MAS/NMR). This paper also reviews immobilisation mechanisms of heavy metals in hydrated cement matrices, focusing on the sorption, precipitation and chemical incorporation of cement hydration products. It is concluded that further research on the phase development during cement hydration in the presence of heavy metals and thermodynamic modelling is needed to improve effectiveness of cement-based s/s and extend this waste management technique

  17. Structurally enhanced anelasticity in Zr-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Caron, A.; Wunderlich, R.; Gu, L.; Fecht, H.-J.

    2011-01-01

    Research highlights: → The authors reports on the occurrence of mesostructure in the Zr 63-x Cu 24 Al x Ni 10 Co 3 with a length scale in the 250-400 nm range, depending on the aluminum content. → The frequency dependence of the longitudinal sound velocity correlates with the measured mesostructural lengths while interpreting the ultrasonic data with the thermoelastic model. → It appears that the mesostructural length scale is a governing parameter for the mechanical behavior of this alloys system. → The present work first demonstrates the interplay of mesostructure and mechanical behavior of metallic glasses. -- Atomic force acoustic microscopy was used to image bulk metallic glasses of composition Zr 63-x Cu 24 Al x Ni 10 Co 3 with 8 < x < 15. The elastic contrast was modulated on a length scale of 250-400 nm. A similar modulation was identified by transmission electron microscopy. Using the thermoelastic, model a good correlation between the observed anelasticity and the evidenced mesostructure was obtained.

  18. Spectral CT metal artifact reduction with an optimization-based reconstruction algorithm

    Science.gov (United States)

    Gilat Schmidt, Taly; Barber, Rina F.; Sidky, Emil Y.

    2017-03-01

    Metal objects cause artifacts in computed tomography (CT) images. This work investigated the feasibility of a spectral CT method to reduce metal artifacts. Spectral CT acquisition combined with optimization-based reconstruction is proposed to reduce artifacts by modeling the physical effects that cause metal artifacts and by providing the flexibility to selectively remove corrupted spectral measurements in the spectral-sinogram space. The proposed Constrained `One-Step' Spectral CT Image Reconstruction (cOSSCIR) algorithm directly estimates the basis material maps while enforcing convex constraints. The incorporation of constraints on the reconstructed basis material maps is expected to mitigate undersampling effects that occur when corrupted data is excluded from reconstruction. The feasibility of the cOSSCIR algorithm to reduce metal artifacts was investigated through simulations of a pelvis phantom. The cOSSCIR algorithm was investigated with and without the use of a third basis material representing metal. The effects of excluding data corrupted by metal were also investigated. The results demonstrated that the proposed cOSSCIR algorithm reduced metal artifacts and improved CT number accuracy. For example, CT number error in a bright shading artifact region was reduced from 403 HU in the reference filtered backprojection reconstruction to 33 HU using the proposed algorithm in simulation. In the dark shading regions, the error was reduced from 1141 HU to 25 HU. Of the investigated approaches, decomposing the data into three basis material maps and excluding the corrupted data demonstrated the greatest reduction in metal artifacts.

  19. Characterization of protein degradation in serum-based lubricants during simulation wear testing of metal-on-metal hip prostheses.

    Science.gov (United States)

    Maskiewicz, Victoria K; Williams, Paul A; Prates, Sarah J; Bowsher, John G; Clarke, Ian C

    2010-08-01

    A size exclusion high performance liquid chromatography (SEC-HPLC) method has been developed which is capable of separation and quantitation of bovine serum albumin (BSA) and bovine serum globulin (BSG) components of serum-based lubricant (SBL) solutions. This allowed characterization of the stability profiles of these proteins when acting as lubricants during hip wear simulation, and identification of wear-specific mechanisms of degradation. Using cobalt-chromium metal-on-metal (MOM) hip joints, it was observed that BSA remained stable for up to 3 days (215K cycles) of wear testing after which the protein degraded in a fairly linear fashion. BSG on the other hand, began to degrade immediately and in a linear fashion with a rate constant of 5% per day. Loss of both proteins occurred via the formation of high molecular weight aggregates which precipitated out of solution. No fragmentation of the polypeptide backbone of either protein was observed. Data obtained suggest that protein degradation was not due to microbial contamination, denaturation at the air-water interface, or frictional heating of articulating joint surfaces in these studies. We conclude that the primary source of protein degradation during MOM simulation testing occurs via high shear rates experienced by SBL solutions at articulating surfaces, possibly coupled with metal-protein interactions occurring as new and reactive metal surfaces are generated during wear testing. The development of this analytical methodology will allow new studies to clarify the role of SBL solutions in wear simulation studies and the interactions and lubricating properties of serum proteins with prosthetic surfaces other than MOM.

  20. Applications of Open Source GMAW-Based Metal 3-D Printing

    Directory of Open Access Journals (Sweden)

    Yuenyong Nilsiam

    2018-03-01

    Full Text Available The metal 3-D printing market is currently dominated by high-end applications, which make it inaccessible for small and medium enterprises, fab labs, and individual makers who are interested in the ability to prototype and additively manufacture final products in metal. Recent progress led to low-cost open-source metal 3-D printers using a gas metal arc welding (GMAW-based print head. This reduced the cost of metal 3-D printers into the range of desktop prosumer polymer 3-D printers. Consequent research established good material properties of metal 3-D printed parts with readily-available weld filler wire, reusable substrates, thermal and stress properties, toolpath planning, bead-width control, mechanical properties, and support for overhangs. These previous works showed that GMAW-based metal 3-D printing has a good adhesion between layers and is not porous inside the printed parts, but they did not proceed far enough to demonstrate applications. In this study, the utility of the GMAW approach to 3-D printing is investigated using a low-cost open-source metal 3-D printer and a converted Computer Numerical Control router machine to make useful parts over a range of applications including: fixing an existing part by adding a 3-D metal feature, creating a product using the substrate as part of the component, 3-D printing in high resolution of useful objects, near net objects, and making an integrated product using a combination of steel and polymer 3-D printing. The results show that GMAW-based 3-D printing is capable of distributed manufacturing of useful products for a wide variety of applications for sustainable development.

  1. Effects of accelerated degradation on metal supported thin film-based solid oxide fuel cell

    DEFF Research Database (Denmark)

    Reolon, R. P.; Sanna, S.; Xu, Yu

    2018-01-01

    A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte and nanostruct......A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte...

  2. Metal-carbon C/Co nanocomposites based on activated pyrolyzed polyacrylonitrile and cobalt particles

    Science.gov (United States)

    Efimov, M. N.; Vasilev, A. A.; Muratov, D. G.; Zemtsov, L. M.; Karpacheva, G. P.

    2017-09-01

    A new way of synthesizing metal-carbon nanocomposites via simultaneous pyrolysis and the chemical activation of a precursor based on polyacrylonitrile and cobalt carbonate under IR radiation is proposed. Structural characteristics of samples synthesized both without alkali and in the activation process are compared. The effect the metal has on the structure of the carbon and the size of its specific surface area is shown. The specific surface area of the sample synthesized with the simultaneous formation of the carbon matrix, its activation, and the reduction of the metal is 1232 m2/g. Cobalt nanoparticles are found to have cubic face-centered and hexagonal close-packed lattices.

  3. Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines

    Directory of Open Access Journals (Sweden)

    M. Manuela M Raposo

    2007-10-01

    Full Text Available The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II and Ni(II metal ions and with diamagnetic Hg(II, as shown by theabsorption and steady-state fluorescence spectroscopy studies. The formation ofmononuclear or dinuclear metal complexes was postulated based on the presence of thefree carboxylic acid as binding site and also with the interaction with the donor atoms inthe chromophore. Interaction with other important biological metal ions such as Zn(II,Ca(II and Na(I was also explored.

  4. Fe-based bulk metallic glasses used for magnetic shielding

    Science.gov (United States)

    Şerban, Va; Codrean, C.; Uţu, D.; Ercuţa, A.

    2009-01-01

    The casting in complex shapes (tubullar) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small adittion of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  5. Metal Speciation in the Rivers Around Potchefstroom Based on Seasonality.

    Science.gov (United States)

    Manyatshe, Alusani; Fosso-Kankeu, Elvis; van der Berg, Divan; Lemmer, Nico; Waanders, Frans; Tutu, Hlanganani

    2018-01-01

      About 44 surface water samples were collected in the wet and dry seasons around mining areas near the city of Potchefstroom in South Africa, and physicochemical parameters were analyzed to assess the speciation of pollutants and impact on dispersion potential. It was found that concentrations of the trace elements measured decreased significantly during the dry season. High concentrations of trace elements during the wet season were correlated to high effluents from anthropogenic sources which were flowing into the surface water. Aqueous metal speciation in both seasons was conducted using the PHREEQC geochemical modelling code. The seasonal variation of species observed was due to changes in the physicochemical quality of water between the two seasons. Collected data indicated that high percentages of Ca and Mg were present as free hydrate species, whereas the Fe, Cd, As, and U were mostly present as carbonate or hydroxide species.

  6. The genesis of the base metal ore deposit from Herja

    Directory of Open Access Journals (Sweden)

    Gheorghe Damian

    2003-04-01

    Full Text Available The Herja ore deposit is one of the most known of the Baia Mare Neogene metallogenetic district and is associated with a complex stock of Pannonian age. The hydrothermal alterations associated with the mineralizations are represented by: the propylitization, the argillization, the phyllic and potassic alteration. The monoascenedant character of the mineralizations is predominant. The magmatic intrusions have been sequential placed and have represented the heat, metals and hydrothermal solutions source. In the first stages of mineralization the hydrothermal solutions contain predominantly magmatic water and in the final stages the water is of connate and meteoric origin. According to the structural magmatic control, to the mineralogical composition and to the hydrothermal alterations, the Herja ore deposits are of a low sulphidation epithermal systems type.

  7. Performance of metal Hall sensors based on copper

    Czech Academy of Sciences Publication Activity Database

    Sentkerestiová, J.; Ďuran, Ivan; Kovařík, Karel; Viererbl, L.; Kohout, Michal

    2013-01-01

    Roč. 88, 6-8 (2013), s. 1310-1314 ISSN 0920-3796. [Symposium on Fusion Technology (SOFT-27)/27./. Liège, 24.09.2012-28.09.2012] R&D Projects: GA MŠk 7G10072; GA MŠk(CZ) LM2011021 Grant - others:EUROATOM(XE) FU07-CT-2007-00060 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : Metal Hall sensor * Magnetic diagnostics * Copper Hall sensor * Fusion reactors * Neutron irradiation Subject RIV: BL - Plasma and Gas Discharge Physics; BM - Solid Matter Physics ; Magnetism (FZU-D) Impact factor: 1.149, year: 2013 http://www.sciencedirect.com/science/article/pii/S0920379613001701#

  8. Screenable silver and base metal solar cell contacts

    Science.gov (United States)

    Ross, B.

    1980-01-01

    The metallurgical soundness of the all-metal screenable thick film electrode system is established for silver and copper electrodes. Silver fluoride was identified as a successful etchant material and is found most effective in the liquid phase (435-460 C). Best results were achieved with the eutectic alloys of dopants and semiconductors. The air-fired silver inks were strongly adherent, rugged, and solderable, whereas the hydrogen-fired silver inks had very poor adhesion. A two-step firing process was devised in which copper inks containing silver fluoride were activated in a nitrogen atmosphere, with sintering done at the same or higher temperatures in hydrogen. Good solar cells were made using the copper paste back contacts demonstrating that the electrodes are not the limiting factors in efficiency.

  9. Fe-based bulk metallic glasses used for magnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Va; Codrean, C; UTu, D [Politehnica University of Timisoara, Depart for Materials Science and Welding, 1, M. Viteazu Bvd., 300222, Timisoara (Romania); ErcuTa, A, E-mail: serban@mec.upt.r [West University of Timisoara, Faculty of Physics, 4, Vasile Parvan Bdv., Timisoara 300223 (Romania)

    2009-01-01

    The casting in complex shapes (tubular) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small addition of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  10. A Comprehensive Review of Glucose Biosensors Based on Nanostructured Metal-Oxides

    Science.gov (United States)

    Rahman, Md. Mahbubur; Saleh Ahammad, A. J.; Jin, Joon-Hyung; Ahn, Sang Jung; Lee, Jae-Joon

    2010-01-01

    Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation. This article concentrates mainly on the development of different nanostructured metal-oxide [such as ZnO, Cu(I)/(II) oxides, MnO2, TiO2, CeO2, SiO2, ZrO2, and other metal-oxides] based glucose biosensors. Additionally, we devote our attention to the operating principles (i.e., potentiometric, amperometric, impedimetric and conductometric) of these nanostructured metal-oxide based glucose sensors. Finally, this review concludes with a personal prospective and some challenges of these nanoscaled sensors. PMID:22399911

  11. Recovery of Precious and Base Metals from Waste Printed Circuit Boards Using a Sequential Leaching Procedure

    Science.gov (United States)

    Batnasan, Altansukh; Haga, Kazutoshi; Shibayama, Atsushi

    2018-02-01

    This paper considers the issue of recycling of waste printed circuit boards (WPCBs) containing precious and base metals in appreciable amounts. High-pressure oxidative leaching (HPOL) with dilute sulfuric acid resulted in removal of a significant amount of base metals from a WPCB ash sample obtained by incineration at 800°C. The parameters investigated in the precious metal leaching from WPCB residue after HPOL included the sulfuric acid concentration, thiourea concentration, oxidant concentration, leaching temperature, and leaching time. Recovery of gold, silver, and palladium of 100%, 81%, and 13% from the WPCB residue sample was achieved by thiourea leaching under optimized conditions. The results show that the efficiency of precious metal dissolution from the WPCB sample using thiourea solution depended strongly on the concentration of both thiourea and oxidant.

  12. Functional nucleic acid-based sensors for heavy metal ion assays.

    Science.gov (United States)

    Zhu, Guichi; Zhang, Chun-yang

    2014-12-21

    Heavy metal contaminants such as lead ions (Pb(2+)), mercury ions (Hg(2+)) and silver ions (Ag(+)) can cause significant harm to humans and generate enduring bioaccumulation in ecological systems. Even though a variety of methods have been developed for Pb(2+), Hg(2+) and Ag(+) assays, most of them are usually laborious and time-consuming with poor sensitivity. Due to their unique advantages of excellent catalytic properties and high affinity for heavy metal ions, functional nucleic acids such as DNAzymes and aptamers show great promise in the development of novel sensors for heavy metal ion assays. In this review, we summarize the development of functional nucleic acid-based sensors for the detection of Pb(2+), Hg(2+) and Ag(+), and especially focus on two categories including the direct assay and the amplification-based assay. We highlight the emerging trends in the development of sensitive and selective sensors for heavy metal ion assays as well.

  13. Use of Ferritin-Based Metal-Encapsulated Nanocarriers as Anticancer Agents

    Directory of Open Access Journals (Sweden)

    Luciana Mosca

    2017-01-01

    Full Text Available The ability of ferritin to bind and deliver metals and metal-based drugs to human neuroblastoma SH-SY5Y cells was studied. We used heavy chain (H ferritin-based metal-containing nanocarriers to test whether these constructs, which are able to cross the blood-brain barrier, may be used for the delivery of toxic molecules to brain cells, and to study their effect on the viability and cellular redox homeostasis of human neuroblastoma cells. We show that metal-containing nanocarriers are efficiently captured by SH-SY5Y cells. Iron-containing nanocarriers have a proliferative effect, while silver and cisplatin-encapsulated nanocarriers determine concentration-dependent neuroblastoma cell death. This work is a proof of concept for the use of ferritins for the delivery of toxic molecules to brain tumors.

  14. Normal metal tunnel junction-based superconducting quantum interference proximity transistor: the N-SQUIPT

    OpenAIRE

    D'Ambrosio, S.; Meissner, M.; Blanc, C.; Ronzani, A.; Giazotto, F.

    2015-01-01

    We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current \\textit{via} the application of an external magnetic field. This results into a drastic suppression of power dissipatio...

  15. Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases

    OpenAIRE

    PAWAR, Vijay; NAIK, Prashant; GIRIDHAR, Rajani; YADAV, Mange Ram

    2014-01-01

    In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanol-amine, and diethylamine) had lowered ...

  16. A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations

    OpenAIRE

    Topal, Giray; Tümerdem, Recep; Basaran, Ismet; Gümüş, Arzu; Cakir, Umit

    2007-01-01

    The constants of the extraction equilibrium and the distribution for dichloromethane as an organic solvent having low dielectric constant of metal cations with chiral Schiff bases, benzaldehydene-(S)-2-amino-3-phenylpropanol (I), ohydroxybenzaldehydene-( S)-2-amino-3-phenyl-propanol (II), benzaldehydene-(S)-2- amino-3-methylbutanol (III) with anionic dyes [4-(2-pyridylazo)-resorcinol mono sodium monohydrate (NaPar), sodium picrat (NaPic) and potassium picrat (KPic)] and some heavy metal chlor...

  17. Zr-based conversion coatings for multi-metal substrates

    NARCIS (Netherlands)

    Cerezo Palacios, J.M.

    2015-01-01

    In this PhD work, a new surface treatment based on the application of Zr-based conversion coatings by immersion in a Cu containing Zr-based conversion solution was investigated as a replacement of the traditional phosphating process for the automotive industry. Nowadays most of the cars are made of

  18. The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants : a phantom study

    NARCIS (Netherlands)

    Harnish, Roy; Prevrhal, Sven; Alavi, Abass; Zaidi, Habib; Lang, Thomas F.

    To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of F-18-fluorodeoxyglucose uptake in lesions near metallic prostheses. A custom

  19. Effect of Microstructure on Hydrogen Diffusion in Weld and API X52 Pipeline Steel Base Metals under Cathodic Protection

    Directory of Open Access Journals (Sweden)

    R. C. Souza

    2017-01-01

    Full Text Available The aim of this research was to evaluate the influence of microstructure on hydrogen permeation of weld and API X52 base metal under cathodic protection. The microstructures analyzed were of the API X52, as received, quenched, and annealed, and the welded zone. The test was performed in base metal (BM, quenched base metal (QBM, annealed base metal (ABM, and weld metal (WM. Hydrogen permeation flows were evaluated using electrochemical tests in a Devanathan cell. The potentiodynamic polarization curves were carried out to evaluate the corrosion resistance of each microstructure. All tests were carried out in synthetic soil solutions NS4 and NS4 + sodium thiosulfate at 25°C. The sodium thiosulfate was used to simulate sulfate reduction bacteria (SRB. Through polarization, assays established that the microstructure does not influence the corrosion resistance. The permeation tests showed that weld metal had lower hydrogen flow than base metal as received, quenched, and annealed.

  20. Complexing of heavy metals with DNA and new bioaffinity method of their determination based on amperometric DNA-based biosensor.

    Science.gov (United States)

    Babkina, S S; Ulakhovich, N A

    2005-09-01

    The immobilized single-stranded DNA (ssIDNA) has been found to be a very effective biospecific analytical reagent when used in a newly developed bioaffinity method of the determination of heavy metals based on the amperometric DNA-based biosensor. This has been concluded from the comparative study of the complexing of heavy metals with double-stranded DNA, single-stranded DNA, and ssIDNA, using Fe(III) and Cu(II) as a model (metal/nucleotide ratio and stability constants are maximum for ssIDNA), from the study of adsorption of Fe(III), Cu(II), Pb(II), and Cd(II) on nitrocellulose membranes, containing single-stranded DNA, and from the determination of their binding constants with ssIDNA. According to these data, the chosen heavy metals can be lined up in a series of binding strengths with ssIDNA: Cu(II) > Pb(II) > Fe(III) > Cd(II). The method of the determination of heavy metals is based on biospecific preconcentration of metal ions on the biosensor followed by the destruction of DNA-metal complexes with ethylenediaminetetraacetate and voltammogram recording has been proposed. The lower detection limits are 4.0 x 10(-11), 1.0 x 10(-10), 1.0 x 10(-9), and 5.0 x 10(-9) M for Cu(II), Pb(II), Cd(II), and Fe(III), respectively. The heavy metals have been assayed in multicomponent environmental and biological systems such as natural and drinking water, milk, and blood serum samples.

  1. Neural networks-based modeling applied to a process of heavy metals removal from wastewaters.

    Science.gov (United States)

    Suditu, Gabriel D; Curteanu, Silvia; Bulgariu, Laura

    2013-01-01

    This article approaches the problem of environment pollution with heavy metals from disposal of industrial wastewaters, namely removal of these metals by means of biosorbents, particularly with Romanian peat (from Poiana Stampei). The study is carried out by simulation using feed-forward and modular neural networks with one or two hidden layers, pursuing the influence of certain operating parameters (metal nature, sorbent dose, pH, temperature, initial concentration of metal ion, contact time) on the amount of metal ions retained on the unit mass of sorbent. In neural network modeling, a consistent data set was used, including five metals: lead, mercury, cadmium, nickel and cobalt, the quantification of the metal nature being done by its electronegativity. Even if based on successive trials, the method of designing neural models was systematically conducted, recording and comparing the errors obtained with different types of neural networks, having various numbers of hidden layers and neurons, number of training epochs, or using various learning methods. The errors with values under 5% make clear the efficiency of the applied method.

  2. Strain-engineering stabilization of BaTi O3 -based polar metals

    Science.gov (United States)

    Ma, Chao; Jin, Kui-juan; Ge, Chen; Yang, Guo-zhen

    2018-03-01

    Polar metals, which possess ferroelectriclike polar structure and conductivity simultaneously, have attracted wide interest since the first solid example, LiOs O3 (below 140 K), was discovered. However, the lack of room-temperature polar metals hinders further research and applications. Thus abundant properties of polar metals are unexplored. Here, with first-principles calculations, we report that the polar metal phase can be stabilized in the strain-engineered BaTi O3 with electron doping. The mechanism relates to the competition between the shifting of the t2 g energy levels and the narrowing of their bandwidth. Surprisingly, it is predicted that the ferroelectric-to-paraelectric transition temperature can be increased by electron doping when the strain is large enough, which holds potential for room-temperature polar metals. Our results indicate that strain engineering is a promising way to achieve BaTi O3 -based polar metals, and they should have practical significance for obtaining easily accessible, ecofriendly, and potential room-temperature polar metals.

  3. Behavior and Potential Impacts of Metal-Based Engineered Nanoparticles in Aquatic Environments

    Directory of Open Access Journals (Sweden)

    Cheng Peng

    2017-01-01

    Full Text Available The specific properties of metal-based nanoparticles (NPs have not only led to rapidly increasing applications in various industrial and commercial products, but also caused environmental concerns due to the inevitable release of NPs and their unpredictable biological/ecological impacts. This review discusses the environmental behavior of metal-based NPs with an in-depth analysis of the mechanisms and kinetics. The focus is on knowledge gaps in the interaction of NPs with aquatic organisms, which can influence the fate, transport and toxicity of NPs in the aquatic environment. Aggregation transforms NPs into micrometer-sized clusters in the aqueous environment, whereas dissolution also alters the size distribution and surface reactivity of metal-based NPs. A unique toxicity mechanism of metal-based NPs is related to the generation of reactive oxygen species (ROS and the subsequent ROS-induced oxidative stress. Furthermore, aggregation, dissolution and ROS generation could influence each other and also be influenced by many factors, including the sizes, shapes and surface charge of NPs, as well as the pH, ionic strength, natural organic matter and experimental conditions. Bioaccumulation of NPs in single organism species, such as aquatic plants, zooplankton, fish and benthos, is summarized and compared. Moreover, the trophic transfer and/or biomagnification of metal-based NPs in an aquatic ecosystem are discussed. In addition, genetic effects could result from direct or indirect interactions between DNA and NPs. Finally, several challenges facing us are put forward in the review.

  4. Novel High-Speed Photopolarimeter Based on a Metallic Grating

    International Nuclear Information System (INIS)

    Du, X L; Dai, J M; Sun, X G

    2006-01-01

    A novel high-speed photopolarimeter is presented in this paper, which is composed by the optical system, electronics system and PC. This instrument uses a metallic grating that can produce both reflective diffraction and transmission diffraction as a beam splitter to divide the incident light into many components, and the light fluxes of the four 1st order diffracted beams are converted linearly into four electrical signals by four photodiodes. After going through a signal conditioning circuit, these electrical signals are converted into digital values by high-speed A/D converters that can implement synchronous multi-channels sampling, and then the data sampled are high-speedily transmitted into the PC via a USB2.0 interface. The electrical signal vector I composed by the four electrical signals possesses the linear relationship with the incident light Stokes vector S. The nonsingular instrument matrix A of this instrument can be obtained by the calibration, and then the unknown Stokes vector S of the incidence light can be obtained from the equation S = A -1 I. The testing results show that the mean deviations of the measured Stokes parameters compared with the predicted values are less than 1% at 632.8nm. It is compact and easy to be installed, and can be used as a polarization state detector in real-time polarimetry and ellipsometry

  5. Polymer waveguide couplers based on metal nanoparticle–polymer nanocomposites

    International Nuclear Information System (INIS)

    Signoretto, M; Suárez, I; Chirvony, V S; Martínez-Pastor, J; Abargues, R; Rodríguez-Cantó, P J

    2015-01-01

    In this work Au nanoparticles (AuNPs) are incorporated into poly(methyl methacrylate) (PMMA) waveguides to develop optical couplers that are compatible with planar organic polymer photonics. A method for growing AuNPs (of 10 to 100 nm in size) inside the commercially available Novolak resist is proposed with the intention of tuning the plasmon resonance and the absorption/scattering efficiencies inside the patterned structures. The refractive index of the MNP–Novolak nanocomposite (MNPs: noble metal nanoparticles) is carefully analysed both experimentally and numerically in order to find the appropriate fabrication conditions (filling factor and growth time) to optimize the scattering cross section at a desired wavelength. Then the nanocomposite is patterned inside a PMMA waveguide to exploit its scattering properties to couple and guide a normal incident laser light beam along the polymer. In this way, light coupling is experimentally demonstrated in a broad wavelength range (404–780 nm). Due to the elliptical shape of the MNPs the nanocomposite demonstrates a birefringence, which enhances the coupling to the TE mode up to efficiencies of around 1%. (paper)

  6. Commercial Metal-Based Nanocolloids - Evaluation of Cytotoxicity

    Directory of Open Access Journals (Sweden)

    Małaczewska Joanna

    2015-04-01

    Full Text Available The purpose of the study was to determine the cytotoxicity of commercial silver, gold, and copper nanocolloids towards two established cell lines (NIH/3T3 and GMK and primary chick embryo cell culture (CECC, using routine colorimetric assays: MTT, NRU, and LDH, which enable a preliminary evaluation of the mechanism of cytotoxic effect of the tested substances. The MTT assay evaluates the activity of mitochondria, NRU assay reveals the damage to lysosomes, while LDH assay shows injuries to the cytoplasmic membrane. The NRU assay proved to be non-applicable to the tested nanocolloids, most probably due to the interaction of nanoparticles with neutral red dye, which affected the colorimetric reaction. The MTT assay was more sensitive than LDH because the intercellular effect of a substance occurs before permanent damage to the cytoplasmic membrane. Silver nanocolloid was distinguished by the highest cytotoxicity, irrespective of the applied cell model, although the other two metals showed some cytotoxic effects as well, with gold nanocolloid being more toxic than copper one. Although the primary chick embryo cell culture, as a model reflecting more faithfully the conditions in a living organism than continuous cell lines, was undistinguished by elevated tolerance to the most toxic silver nanocolloid, it showed the tendency to recovery from the growth suppression with longer exposure after the application of less toxic gold and copper nanocolloids.

  7. Advanced Coatings from Natural-Based Polymers for Metals

    National Research Council Canada - National Science Library

    Sugama, Toshifumi

    2000-01-01

    ... natural polysaccharide biopolymers originating from pectin, starch, and chitosan as renewable agricultural and marine resources, and on assessing their potential as the corrosion-preventing water-based...

  8. Biomaterial based novel polyurethane adhesives for wood to wood and metal to metal bonding

    OpenAIRE

    Patel,Mitesh Ramanlal; Shukla,Jignesh Markandray; Patel,Natvarbhai Khodidas; Patel,Ketan Haribhai

    2009-01-01

    Polyurethane adhesives made from synthetic chemicals are non-biodegradable, costly and difficult to find raw materials from local market. To avoid solid pollution problem, cost effectiveness and easy availability of raw materials, biomaterials based polyurethane adhesives are used in current industrial interest. Direct use of castor oil in polyurethane adhesive gives limited hardness. Modification on active sites of castor oil to utilize double bond of unsaturated fatty acid and carboxyl grou...

  9. Novel Base Metal-Palladium Catalytic Diesel Filter Coating with NO2 Reducing Properties

    DEFF Research Database (Denmark)

    Johansen, K.; Dahl, S.; Mogensen, G.

    2007-01-01

    A novel alternative base metal/palladium coat has been developed that has limited NO2 formation and which even removes NO2 in a wide temperature range.Soot combustion, HC conversion and CO conversion properties are comparable to current platinum based solutions but the coating has a more attracti...

  10. Luminescent Stability of Hybrids Based on Different Borate Glass Matrix’s and Organic Metal Complexes

    Science.gov (United States)

    Petrova, Olga; Avetisov, Roman; Akkuzina, Alina; Anurova, Mariia; Mozhevitina, Elena; Khomyakov, Andrew; Taydakov, Ilya; Avetissov, Igor

    2017-08-01

    The stability of the luminescent properties of new hybrid materials based on 8-oxyquinoline metal (Li, Rb, Sr) complexes and Eu complex with phenanthroline and low-melting Pb-based inorganic glass matrixes under conditions of prolonged exposure under ambient conditions and heating above the glass transition temperature of the matrix’s has been investigated.

  11. Corrosion of metals in treated wood examined by synchrotron based xanes and XFM

    Science.gov (United States)

    Samuel L. Zelinka; Joseph E. Jakes; Grant T. Kirker; Leandro Passarini; Barry Lai

    2016-01-01

    Copper based waterborne wood preservatives are frequently used to extend the service life of wood products used in outdoor environments. While these copper based treatments protect the wood from fungal decay and insect attack, they increase the corrosion of metals embedded or in contact with the treated wood. Over the past ten years, several studies have looked at the...

  12. Large capacitance enhancement induced by metal-doping in graphene-based supercapacitors: a first-principles-based assessment.

    Science.gov (United States)

    Paek, Eunsu; Pak, Alexander J; Hwang, Gyeong S

    2014-08-13

    Chemically doped graphene-based materials have recently been explored as a means to improve the performance of supercapacitors. In this work, we investigate the effects of 3d transition metals bound to vacancy sites in graphene with [BMIM][PF6] ionic liquid on the interfacial capacitance; these results are compared to the pristine graphene case with particular attention to the relative contributions of the quantum and electric double layer capacitances. Our study highlights that the presence of metal-vacancy complexes significantly increases the availability of electronic states near the charge neutrality point, thereby enhancing the quantum capacitance drastically. In addition, the use of metal-doped graphene electrodes is found to only marginally influence the microstructure and capacitance of the electric double layer. Our findings indicate that metal-doping of graphene-like electrodes can be a promising route toward increasing the interfacial capacitance of electrochemical double layer capacitors, primarily by enhancing the quantum capacitance.

  13. [Mapping Critical Loads of Heavy Metals for Soil Based on Different Environmental Effects].

    Science.gov (United States)

    Shi, Ya-xing; Wu, Shao-hua; Zhou, Sheng-lu; Wang, Chun-hui; Chen, Hao

    2015-12-01

    China's rapid development of industrialization and urbanization causes the growing problem of heavy metal pollution of soil, threatening environment and human health. Therefore, prevention and management of heavy metal pollution become particularly important. Critical loads of heavy metals are an important management tool that can be utilized to prevent the occurrence of heavy metal pollution. Our study was based on three cases: status balance, water environmental effects and health risks. We used the steady-state mass balance equation to calculate the critical loads of Cd, Cu, Pb, Zn at different effect levels and analyze the values and spatial variation of critical loads. In addition, we used the annual input fluxes of heavy metals of the agro-ecosystem in the Yangtze River delta and China to estimate the proportion of area with exceedance of critical loads. The results demonstrated that the critical load value of Cd was the minimum, and the values of Cu and Zn were lager. There were spatial differences among the critical loads of four elements in the study area, lower critical loads areas mainly occurred in woodland and high value areas distributed in the east and southwest of the study area, while median values and the medium high areas mainly occurred in farmland. Comparing the input fluxes of heavy metals, we found that Pb and Zn in more than 90% of the area exceeded the critical loads under different environmental effects in the study area. The critical load exceedance of Cd mainly occurred under the status balance and the water environmental effect, while Cu under the status balance and water environmental effect with a higher proportion of exceeded areas. Critical loads of heavy metals at different effect levels in this study could serve as a reference from effective control of the emissions of heavy metals and to prevent the occurrence of heavy metal pollution.

  14. Research on Ground Motion Metal Target Based on Rocket Projectile by Using Millimeter Wave Radiometer Technology

    Directory of Open Access Journals (Sweden)

    Zhang Dongyang

    2014-06-01

    Full Text Available How to detect the ground motion metal target effectively is an important guarantee for precision strike in the process of Rocket Projectile flight. Accordingly and in view of the millimeter- wave radiation characteristic of the ground motion metal target, a mathematical model was established based on Rocket Projectile about millimeter-wave detection to the ground motion metal target. Through changing various parameters in the process of Rocket Projectile flight, the detection model was studied by simulation. The parameters variation and effective range of millimeter wave radiometer were obtained in the process of rotation and horizontal flight. So a certain theoretical basis was formed for the precision strike to the ground motion metal target.

  15. Dealloying of Cu-Based Metallic Glasses in Acidic Solutions: Products and Energy Storage Applications.

    Science.gov (United States)

    Wang, Zhifeng; Liu, Jiangyun; Qin, Chunling; Yu, Hui; Xia, Xingchuan; Wang, Chaoyang; Zhang, Yanshan; Hu, Qingfeng; Zhao, Weimin

    2015-04-29

    Dealloying, a famous ancient etching technique, was used to produce nanoporous metals decades ago. With the development of dealloying techniques and theories, various interesting dealloying products including nanoporous metals/alloys, metal oxides and composites, which exhibit excellent catalytic, optical and sensing performance, have been developed in recent years. As a result, the research on dealloying products is of great importance for developing new materials with superior physical and chemical properties. In this paper, typical dealloying products from Cu-based metallic glasses after dealloying in hydrofluoric acid and hydrochloric acid solutions are summarized. Several potential application fields of these dealloying products are discussed. A promising application of nanoporous Cu (NPC) and NPC-contained composites related to the energy storage field is introduced. It is expected that more promising dealloying products could be developed for practical energy storage applications.

  16. Raman spectroscopy study of metal-containing boron carbide-based ceramics

    Science.gov (United States)

    Radev, Dimitar D.; Mihailova, Boriana; Konstantinov, Ludmil

    2002-01-01

    Dense boron carbide-based materials, B 4C-Me xB y (Me = V, W), are obtained by pressureless sintering in the presence of metal carbides. The sintered B 4CVB 2 and B 4CW 2B 5 ceramics, with various contents of the metal borides, are investigated by powder X-ray diffraction and Raman spectroscopy. The results obtained show that the non-homogeneity of the ceramic samples increases with increasing the content of metal and, additionally, metal cations replace a part of boron atoms in icosahedra positions in the B 4C network, thus stiffening the B 4C lattice and improving the micro-hardness and the wear resistance of the boron carbide ceramics.

  17. Experimental study on the surface characteristics of Pd-based bulk metallic glass

    International Nuclear Information System (INIS)

    Zhang, Xiang; Sun, Bingli; Zhao, Na; Li, Qian; Hou, Jianhua; Feng, Weina

    2014-01-01

    Highlights: • Wetting behavior of four polymer melts on Pd-based bulk metallic glass was investigated. • From results, in general, the contact angle of polymer on Pd-based BMG decreases with temperature increasing. • We find a critical temperature for each polymer, above this temperature, contact angle on Pd-based BMG does not decrease with temperature increasing. • Surface free energy of Pd-based BMG was estimated by Owens–Wendt method. - Abstract: The metallic glass has many unique and desirable physical and chemical characteristics for their long-range disordered atomic structure, among them the interfacial properties of the metallic glasses are crucial for their applications and manufacturing. In this work, the contact wetting angles between the polymer melts and Pd 40 Cu 30 Ni 10 P 20 bulk metallic glass (Pd-BMG) with four kinds of roughness were analyzed. Experiments show the order of four polymers wettability on Pd-BMG was PP > HDPE > COC > PC. The surface free energy of Pd-BMG was estimated by Owens–Wendt method using the contact angles of three testing liquids. Neumann method was also used to further evidence the surface free energy of Pd-BMG comparing with PTFE, mold steels NAK80 and LKM2343ESR. The results provide theoretical and technical supports for the fabrication of metallic glass micro mold and the parameter optimization of polymer micro injection molding

  18. Influence of metallic based fuel additives on performance and exhaust emissions of diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Keskin, Ali [Tarsus Technical Education Faculty, Mersin University, 33500 Mersin (Turkey); Guerue, Metin, E-mail: mguru@gazi.edu.t [Engineering and Architectural Faculty, Gazi University, 06570 Maltepe, Ankara (Turkey); Altiparmak, Duran [Technical Education Faculty, Gazi University, 06500 Ankara (Turkey)

    2011-01-15

    In this experimental study, influence of the metallic-based additives on fuel consumption and exhaust emissions of diesel engine were investigated. The metallic-based additives were produced by synthesizing of resin acid (abietic acid) with MnO{sub 2} or MgO. These additives were doped into diesel fuel at the rate of 8 {mu}mol/l and 16 {mu}mol/l for preparing test fuels. Both additives improved the properties of diesel fuel such as viscosity, flash point, cloud point and pour point. The fuels with and without additives were tested in a direct injection diesel engine at full load condition. Maximum reduction of specific fuel consumption was recorded as 4.16%. CO emission and smoke opacity decreased by 16.35% and by 29.82%, respectively. NO{sub x} emission was measured higher and CO{sub 2} emission was not changed considerably with the metallic-based additives.

  19. Enhanced thermoelectric properties of metal film on bismuth telluride-based materials

    International Nuclear Information System (INIS)

    Chao, Wen Hsuan; Chen, Yi Ray; Tseng, Shih Chun; Yang, Ping Hsing; Wu, Ren Jye; Hwang, Jenn Yeu

    2014-01-01

    Diffusion barriers have a significant influence on the reliability and life time of thermoelectric modules. Although nickel is commonly used as a diffusion barrier in commercial thermoelectric modules, several studies have verified that Ni migrates to bismuth telluride-based material during high temperature cycles and causes a loss in efficacy. In this paper, the influence of metal layers coated to p-type and n-type Bi 2 Te 3 on the interface characterization and thermoelectric property is studied using a RF magnetron sputtering. The findings from this study demonstrate the structural and thermoelectric properties of p-type and n-type Bi 2 Te 3 coated with different metal layers. The crystalline phase and compositional change of the interface between the Bi 2 Te 3 materials and the metal layers were determined using an X-ray diffractometer and scanning electron microscopy with energy dispersive spectroscopy. Formation of NiTe was observed in the sample of Ni/p-type Bi 2 Te 3 based films post-annealed in an N 2 atmosphere at 200 °C. In contrast, no Co x Te y was formed in the sample of Co/p-type Bi 2 Te 3 based films post-annealed at 200 °C. For as-deposited Ni/p-type and n-type Bi 2 Te 3 based legs, the Ni slightly diffused into the Bi 2 Te 3 based legs. A similar phenomenon also occurred in the as-deposited Co/p-type and n-type Bi 2 Te 3 based legs. The Seebeck coefficients of the Co contacts on the Bi 2 Te 3 based material displayed better behavior than those of the Ni contacts on the Bi 2 Te 3 based legs. Thus Co could be a suitable diffusion barrier for bulk Bi 2 Te 3 based material. The observed effects on the thermoelectric and structural properties of metal/Bi 2 Te 3 based material are crucial for understanding the interface between the diffusion barrier and thermoelectric materials. - Highlights: • Interface characterization of metal coated to p-type and n-type Bi 2 Te 3 is studied. • We examined the phase transformation of metal/Bi 2 Te 3 based films

  20. Compact wideband plasmonic filter with flat-top transmission response based on corrugated metal-insulator-metal ring resonator.

    Science.gov (United States)

    Yang, Liu; Zhou, Yong Jin; Zhang, Chao; Xiao, Qian Xun

    2017-10-27

    We demonstrate a novel route to control the filtering of spoof localized surface plasmons (LSPs) on the corrugated metal-insulator-metal (MIM) ring resonator. The spoof LSPs resonance modes can be effectively tuned to achieve broad passband (covering the quadrupole mode and the hexapole mode) by selecting proper lengths in the input and output coupling area. The mutual coupling between the input and output lines produces the flat-top transmission response and sharp out-of-band rejection. Compared with the wideband bandpass filters based on spoof plasmonic waveguides, the proposed filter is ultra-compact and only 0.35λ*0.35λ. In order to further improve the property of the bandpass plasmonic filter, all the out-of-band frequencies (the dipole mode and the octopole mode) have been rejected by introducing a shunt stepped-impedance resonator and double C-shaped rings on the back of the substrate of the filter. Simulated results are confirmed via experiment, showing good rejection and wideband filtering performance with low insertion loss, flat-top transmission response and sharp out-of-band suppression. The proposed filter can find more applications in the highly integrated plasmonic circuits and systems in both terahertz and microwave regimes.

  1. Structure Analyses of Fe-based Metallic Glasses by Electron Diffraction

    Directory of Open Access Journals (Sweden)

    Akihiko Hirata

    2010-12-01

    Full Text Available Nanoscale structural information of amorphous structures has become obtainable by using nanobeam electron diffraction in combination with high resolution imaging. In addition, accurate radial distribution function analysis using energy filter has also become available to know averaged amorphous structures. In this paper, we introduce some applications of these techniques, especially to several Fe-based metallic glasses. On the basis of these results, we discuss a relationship between the glass structure and the glass stability in Fe-based metallic glasses

  2. Polyetheretherketone Overlay Prosthesis over High Noble Ball Attachments to Overcome Base Metal Sensitivity: A Clinical Report.

    Science.gov (United States)

    Zoidis, Panagiotis

    2018-01-11

    A modified polyetheretherketone (PEEK) framework material in combination with heat-polymerized denture base acrylic resin was used for the fabrication of an overlay prosthesis for a patient sensitive to base metals. High noble metal was used for the fabrication of the post/coping/ball attachment assemblies to promote retention and stability. These protruding attachments into the acrylic resin could result in stress concentration; therefore, a framework is often used to strengthen the prosthesis. PEEK frameworks could be a treatment alternative to high noble or Ti frameworks since they combine good mechanical properties with biocompatibility, reduced cost, and common laboratory procedures. © 2018 by the American College of Prosthodontists.

  3. Stability and electronic structure of Zr-based ternary metallic glasses and relevant compounds

    International Nuclear Information System (INIS)

    Hasegawa, M.; Soda, K.; Sato, H.; Suzuki, T.; Taketomi, T.; Takeuchi, T.; Kato, H.; Mizutani, U.

    2007-01-01

    The electronic structure of the Zr-based metallic glasses has been investigated by theoretical and experimental approaches. One approach is band calculations of the Zr 2 Ni (Zr 66.7 Ni 33.3 ) compound to investigate the electronic structure of the Zr 66.7 Ni 33.3 metallic glass (ΔT x = 0 K) of which the local atomic structure is similar to that of the Zr 2 Ni compound. The other is photoemission spectroscopy of the Zr 50 Cu 35 Al 15 bulk metallic glass (BMG) (ΔT x = 69 K). Here ΔT x = T x - T g where T x and T g are crystallization and glass transition temperature, respectively. Both results and previous ones on the Zr 55 Cu 30 Ni 5 Al 10 BMG indicate that there is a pseudogap at the Fermi level in the electronic structure of these Zr-based metallic glasses, independent of the value of the ΔT x . This implies that the pseudogap at the Fermi level is one of the factors that stabilize the glass phase of Zr-based metallic glasses

  4. Viscous surface flow induced on Ti-based bulk metallic glass by heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kun [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Hu, Zheng [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Science and Technology on Vehicle Transmission Laboratory, China North Vehicle Research Institute, Beijing 100072 (China); Li, Fengjiang [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wei, Bingchen, E-mail: weibc@imech.ac.cn [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-12-30

    Highlights: • Obvious smoothing and roughening phases on the Ti-based MG surface resulted, which correspond respectively to the normal and off-normal incidence angles. • Atomic force microscopy confirms two types of periodic ripples distributed evenly over the rough surface. • The irradiation-induced viscosity of MG is about 4×10{sup 12} Pa·s, which accords with the theoretical prediction for metallic glasses close to glass transition temperature. • Surface-confined viscous flow plays a dominant quantitative role, which is due to radiation-induced softening of the low-viscosity surface layer. - Abstract: Ti-based bulk metallic glass was irradiated by a 20 MeV Cl{sup 4+} ion beam under liquid-nitrogen cooling, which produced remarkable surface smoothing and roughening that respectively correspond to normal and off-normal incidence angles of irradiation. Atomic force microscopy confirms two types of periodic ripples distributed evenly over the rough glass surface. In terms of mechanism, irradiation-induced viscosity agrees with the theoretical prediction for metallic glasses near glass transition temperature. Here, a model is introduced, based on relaxation of confined viscous flow with a thin liquid-like layer, that explains both surface smoothing and ripple formation. This study demonstrates that bulk metallic glass has high morphological instability and low viscosity under ion irradiation, which assets can pave new paths for metallic glass applications.

  5. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    Science.gov (United States)

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and…

  6. A dysprosium-based metal-organic framework: Synthesis ...

    Indian Academy of Sciences (India)

    -BSA adduct was assumed to be the .... A Dy-based MOF and biological activity ... Crystal data and details of refinement for com- pound 1. Empirical Formula. C21H32Ca1.50DyN3O22.50. Formula Weight. 909.12. Crystal System. Monoclinic.

  7. Effects of Er:YAG laser treatments on surface roughness of base metal alloys.

    Science.gov (United States)

    Kunt, Göknil Ergün; Güler, Ahmet Umut; Ceylan, Gözlem; Duran, Ibrahim; Ozkan, Pelin; Kirtiloğlu, Tuğrul

    2012-01-01

    We investigated the effects of different Er:YAG laser treatments on the surface roughness of base metal alloys. A total of 36 specimens were prepared of two base metal alloys (Wiron 99, Bellabond plus). The surfaces of the specimens were standardized by gradual wet grinding with 320-, 600-, 800- and 1,000-grit silicon carbide paper for 10 s each on a grinding machine at 300 rpm. Specimens of each alloy were randomly divided into six groups (n = 6) comprising a control group (group C), a group sandblasted with Al(2)O(3) powder at 60 psi for 10 s through a nozzle at a distance of 10 mm (group S), and four Er:YAG laser (Fotona AT) treatment groups. The laser treatment groups were as follows: 500 mJ, 10 Hz, 100 μs (group 500MSP); 500 mJ, 10 Hz, 300 μs (group 500SP); 400 mJ, 10 Hz, 100 μs (group 400MSP); and 400 mJ, 10 Hz, 300 μs (group 400SP). Surface roughness measurements (Ra) were performed using a profilometer. The data were analysed by two-way ANOVA, and mean values were compared using Tukey's HSD test (α = 0.05). According to the two-way ANOVA results, the base metal alloys and interaction between base metal alloy and surface treatment were not statistically significant different (p > 0.05), the surface treatments were significantly different (p metal alloy groups, no significant differences were observed among the control, 400MSP, and 400SP groups (p = 0.912), and these groups demonstrated the lowest Ra values. The highest Ra value was observed in group S (p laser treatment at 400 and 500 mJ/10 Hz is not an alternative method for surface roughening of base metal alloys.

  8. Transparent electrode designs based on optimal nano-patterning of metallic films

    KAUST Repository

    Catrysse, Peter B.

    2010-09-10

    Transparent conductive electrodes are critical to the operation of optoelectronic devices, such as photovoltaic cells and light emitting diodes. Effective electrodes need to combine excellent electrical and optical properties. Metal oxides, such as indium tin oxide, are commonly used. There is substantial interest in replacing them, however, motivated by practical problems and recent discoveries regarding the optics of nano-patterned metals. When designing nano-patterned metallic films for use as electrodes, one needs to account for both optical and electrical properties. In general, it is insufficient to optimize nano-structured films based upon optical properties alone, since structural variations will also affect the electrical properties. In this work, we investigate the need for simultaneous optical and electrical performance by analyzing the optical properties of a class of nano-patterned metallic electrodes that is obtained by a constant-sheet-resistance transformation. Within such a class the electrical and optical properties can be separated, i.e., the sheet resistance can be kept constant and the transmittance can be optimized independently. For simple one-dimensional periodic patterns with constant sheet-resistance, we find a transmission maximum (polarization-averaged) when the metal sections are narrow (< 40 nm, ~ 10% metal fill-factor) and tall (> 100 nm). Our design carries over to more complex two-dimensional (2D) patterns. This is significant as there are no previous reports regarding numerical studies on the optical and electrical properties of 2D nano-patterns in the context of electrode design.

  9. Synthesis, characterization, anti-microbial, DNA binding and cleavage studies of Schiff base metal complexes

    Directory of Open Access Journals (Sweden)

    Poomalai Jayaseelan

    2016-09-01

    Full Text Available A novel Schiff base ligand has been prepared by the condensation between butanedione monoxime with 3,3′-diaminobenzidine. The ligand and metal complexes have been characterized by elemental analysis, UV, IR, 1H NMR, conductivity measurements, EPR and magnetic studies. The molar conductance studies of Cu(II, Ni(II, Co(II and Mn(II complexes showed non-electrolyte in nature. The ligand acts as dibasic with two N4-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The spectroscopic data of metal complexes indicated that the metal ions are complexed with azomethine nitrogen and oxyimino nitrogen atoms. The binuclear metal complexes exhibit octahedral arrangements. DNA binding properties of copper(II metal complex have been investigated by electronic absorption spectroscopy. Results suggest that the copper(II complex bind to DNA via an intercalation binding mode. The nucleolytic cleavage activities of the ligand and their complexes were assayed on CT-DNA using gel electrophoresis in the presence and absence of H2O2. The ligand showed increased nuclease activity when administered as copper complex and copper(II complex behave as efficient chemical nucleases with hydrogen peroxide activation. The anti-microbial activities and thermal studies have also been studied. In anti-microbial activity all complexes showed good anti-microbial activity higher than ligand against gram positive, gram negative bacteria and fungi.

  10. BODIPY-based fluorometric sensor array for the highly sensitive identification of heavy-metal ions.

    Science.gov (United States)

    Niu, Li-Ya; Li, Hui; Feng, Liang; Guan, Ying-Shi; Chen, Yu-Zhe; Duan, Chun-Feng; Wu, Li-Zhu; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-05-02

    A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Rapid Detection of Transition Metals in Welding Fumes Using Paper-Based Analytical Devices

    Science.gov (United States)

    Volckens, John

    2014-01-01

    Metals in particulate matter (PM) are considered a driving factor for many pathologies. Despite the hazards associated with particulate metals, personal exposures for at-risk workers are rarely assessed due to the cost and effort associated with monitoring. As a result, routine exposure assessments are performed for only a small fraction of the exposed workforce. The objective of this research was to evaluate a relatively new technology, microfluidic paper-based analytical devices (µPADs), for measuring the metals content in welding fumes. Fumes from three common welding techniques (shielded metal arc, metal inert gas, and tungsten inert gas welding) were sampled in two welding shops. Concentrations of acid-extractable Fe, Cu, Ni, and Cr were measured and independently verified using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results from the µPAD sensors agreed well with ICP-OES analysis; the two methods gave statistically similar results in >80% of the samples analyzed. Analytical costs for the µPAD technique were ~50 times lower than market-rate costs with ICP-OES. Further, the µPAD method was capable of providing same-day results (as opposed several weeks for ICP laboratory analysis). Results of this work suggest that µPAD sensors are a viable, yet inexpensive alternative to traditional analytic methods for transition metals in welding fume PM. These sensors have potential to enable substantially higher levels of hazard surveillance for a given resource cost, especially in resource-limited environments. PMID:24515892

  12. Creep behaviour of austenitic stainless steels, base and weld metals used in liquid metal fast breeder reactors, during temperature variations

    International Nuclear Information System (INIS)

    Felsen, M.F.

    1982-07-01

    Creep rupture and deformation during temperature variations have been studied for 316 austenitic steel, base and weld metals. Loaded specimens were heated to 900 0 C or 1000 0 C and maintained at this temperature for different durations. The heating rate to these temperatures was between 5 and 50 0 C h -1 , whilst the cooling rate was between 5 and 20 0 C h -1 . The above tests were coupled with short time creep and tensile tests (straining rate 10 -2 h -1 to 10 3 h -1 ) at constant temperature. These tests were used for predicting the creep behaviour of the materials under changing temperature condition. The predictions were in good agreement with the changing temperature and creep experimental results. In addition, a correlation between certains tensile properties, such as the rupture time as a function of stress was observed at high temperature

  13. Magnetic properties of fcc Ni-based transition metal alloy

    Czech Academy of Sciences Publication Activity Database

    Kudrnovský, Josef; Drchal, Václav; Bruno, P.

    2008-01-01

    Roč. 77, č. 22 (2008), 224422/1-224422/8 ISSN 1098-0121 R&D Projects: GA MŠk OC 150; GA AV ČR IAA100100616; GA ČR GA202/07/0456 Institutional research plan: CEZ:AV0Z10100520 Keywords : Ni-based alloys * magnetic properties * Curie temperatures Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008

  14. Metal Iodate-Based Energetic Composites and Their Combustion and Biocidal Performance.

    Science.gov (United States)

    Wang, H; Jian, G; Zhou, W; DeLisio, J B; Lee, V T; Zachariah, M R

    2015-08-12

    The biological agents that can be weaponized, such as Bacillus anthracis, pose a considerable potential public threat. Bacterial spores, in particular, are highly stress resistant and cannot be completely neutralized by common bactericides. This paper reports on synthesis of metal iodate-based aluminized electrospray-assembled nanocomposites which neutralize spores through a combined thermal and chemical mechanism. Here metal iodates (Bi(IO3)3, Cu(IO3)2, and Fe(IO3)3) act as a strong oxidizer to nanoaluminum to yield a very exothermic and violent reaction, and simultaneously generate iodine as a long-lived bactericide. These microparticle-assembled nanocomposites when characterized in terms of reaction times and temporal pressure release show significantly improved reactivity. Furthermore, sporicidal performance superior to conventional metal-oxide-based thermites clearly shows the advantages of combining both a thermal and biocidal mechanism in spore neutralization.

  15. Reversible light-controlled conductance switching of azobenzene-based metal/polymer nanocomposites

    International Nuclear Information System (INIS)

    Pakula, Christina; Zaporojtchenko, Vladimir; Strunskus, Thomas; Faupel, Franz; Zargarani, Dordaneh; Herges, Rainer

    2010-01-01

    We present a new concept of light-controlled conductance switching based on metal/polymer nanocomposites with dissolved chromophores that do not have intrinsic current switching ability. Photoswitchable metal/PMMA nanocomposites were prepared by physical vapor deposition of Au and Pt clusters, respectively, onto spin-coated thin poly(methylmethacrylate) films doped with azo-dye molecules. High dye concentrations were achieved by functionalizing the azo groups with tails and branches, thus enhancing solubility. The composites show completely reversible optical switching of the absorption bands upon alternating irradiation with UV and blue light. We also demonstrate reversible light-controlled conductance switching. This is attributed to changes in the metal cluster separation upon isomerization based on model experiments where analogous conductance changes were induced by swelling of the composite films in organic vapors and by tensile stress.

  16. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Escribano, J. A.; Ferrari, B.; Alvaredo, P.; Gordo, E.; Sanchez-Herencia, A. J.

    2013-07-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  17. Synthesis and Structural Characterization of Carboxylate-Based Metal-Organic Frameworks and Coordination Networks

    Science.gov (United States)

    Calderone, Paul

    Coordination networks (CNs) and metal-organic frameworks (MOFs) are crystalline materials composed of metal ions linked by multifunctional organic ligands. From these connections, infinite arrays of one-, two-, or three-dimensional networks can be formed. Exploratory synthesis and research of novel CNs and MOFs is of current interest because of their many possible industrial applications including gas storage, catalysis, magnetism, and luminescence. A variety of metal centers and organic ligands can be used to synthesize MOFs and CNs under a range of reaction conditions, leading to extraordinary structural diversity. The characteristics of the metals and linkers, such as properties and coordination preferences, play the biggest role in determining the structure and properties of the resulting network. Thus, the choice of metal and linker is dictated by the desired traits of the target network. The pervasive use of transition metal centers in MOF synthesis stems from their well-known coordination behavior with carboxylate-based linkers, thus facilitating design strategies. Conversely, CNs and MOFs based on s-block and lanthanide metals are less studied because each group presents unique challenges to structure prediction. Lanthanide metals have variable coordination spheres capable of accommodating up to twelve atoms, while the bonding in s-block metals takes on a mainly ionic character. In spite of these obstacles, lanthanide and s-block CNs are worthwhile synthetic targets because of their unique properties. Interesting photoluminescent and sensing materials can be developed using lanthanide metals, whereas low atomic weight s-block metals may afford an advantage in gravimetric advantages for gas storage applications. The aim of this research was to expand the current understanding of carboxylate-based CN and MOF synthesis by varying the metals, solvents, and temperatures used. To this end, magnesium-based CNs were examined using a variety of aromatic carboxylate

  18. Identification of metal ion binding sites based on amino acid sequences

    Science.gov (United States)

    Cao, Xiaoyong; Zhang, Xiaojin; Gao, Sujuan; Ding, Changjiang; Feng, Yonge; Bao, Weihua

    2017-01-01

    The identification of metal ion binding sites is important for protein function annotation and the design of new drug molecules. This study presents an effective method of analyzing and identifying the binding residues of metal ions based solely on sequence information. Ten metal ions were extracted from the BioLip database: Zn2+, Cu2+, Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Na+, K+ and Co2+. The analysis showed that Zn2+, Cu2+, Fe2+, Fe3+, and Co2+ were sensitive to the conservation of amino acids at binding sites, and promising results can be achieved using the Position Weight Scoring Matrix algorithm, with an accuracy of over 79.9% and a Matthews correlation coefficient of over 0.6. The binding sites of other metals can also be accurately identified using the Support Vector Machine algorithm with multifeature parameters as input. In addition, we found that Ca2+ was insensitive to hydrophobicity and hydrophilicity information and Mn2+ was insensitive to polarization charge information. An online server was constructed based on the framework of the proposed method and is freely available at http://60.31.198.140:8081/metal/HomePage/HomePage.html. PMID:28854211

  19. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Yang, Weiming; Sun, Baoan; Zhao, Yucheng; Li, Qiang; Hou, Long; Luo, Ning; Dun, Chaochao; Zhao, Chengliang; Ma, Zhanguo; Liu, Haishun; Shen, Baolong

    2016-01-01

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe 50 Ni 30 P 13 C 7 glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe 50 Ni 30 P 13 C 7 metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  20. Ultrafast Transient Absorption Spectroscopy of Polymer-Based Organophotoredox Catalysts Mimicking Transition-Metal Complexes

    Science.gov (United States)

    Jamhawi, Abdelqader; Paul, Anam C.; Smith, Justin D.; Handa, Sachin; Liu, Jinjun

    2017-06-01

    Transition-metal complexes of rare earth metals including ruthenium and iridium are most commonly employed as visible-light photocatalysts. Despite their highly important and broad applications, they have many disadvantages including high cost associated with low abundance in earth crust, potential toxicity, requirement of specialized ligands for desired activity, and difficulty in recycling of metal contents as well as associated ligands. Polymer-based organophotoredox catalysts are promising alternatives and possess unique advantages such as easier synthesis from inexpensive starting material, longer excited state life time, broad range of activity, sustainability, and recyclability. In this research talk, time-resolved photoluminescence and femtosecond transient absorption (TA) spectroscopy measurements of three novel polymer-based organophotoredox catalysts will be presented. By our synthetic team, their catalytic activity has been proven in some highly valuable chemical transformations, that otherwise require transition metal complexes. Time-resolved spectroscopic investigations have demonstrated that photoinduced processes in these catalysts are similar to the transition metal complexes. Especially, intramolecular vibrational relaxation, internal conversion, and intersystem crossing from the S1 state to the T1 state all occur on a sub-picosecond timescale. The long lifetime of the T1 state ( 2-3 microsecond) renders these polymers potent oxidizing and reducing agents. A spectroscopic and kinetic model has been developed for global fitting of TA spectra in both the frequency and time domains. Implication of the current ultrafast spectroscopy studies of these novel molecules to their roles in photocatalysis will be discussed.

  1. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weiming [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Sun, Baoan [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Zhao, Yucheng, E-mail: zhaoyc1972@163.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Li, Qiang [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Hou, Long; Luo, Ning [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Dun, Chaochao [Department of Physics, Wake Forest University, Winston Salem, NC 27109 (United States); Zhao, Chengliang [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Ma, Zhanguo [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Haishun, E-mail: liuhaishun@126.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Shen, Baolong [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-08-15

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  2. Effect of Repeated Firings of Porcelain on Bond Strength of Two Base Metal Alloys

    Directory of Open Access Journals (Sweden)

    Gerami Panah F

    2001-05-01

    Full Text Available The formation of oxides on the surface of the metal are proven to contribute to the formation of strong bonding. However, The base metal alloys are expected to exhibit more oxidation than high gold alloys, increase in oxide layer thickness due to repeated firing in them can reduce the bond strength. The aim of this study was to compare the effect of repeated porcelain firing on the bond strength of two base metal alloys (Minalux and Verabond II. Sixteen metal plates (20x5x0.5 from each alloy were cast and prepared according to the manufacturers' instruction. Porcelain with uniform thickness (Imm was applied on the middle one third of metal plates. After this stage, each alloy group divided to three subgroups. Group I was fired for the second time to form the final glaze, group II and III were fired two and four more times respectively. Specimens were subjected to 3-point flexural test in a digital tritest machine. Results showed no significant differences between bond strength of two alloys. Also results showed repeated firing had no significant effect on bond strength. Due to these findings, this study support similarity of two alloys (Minalux and Verabond II in their bond strength with porcelain.

  3. Pharmaceutical development of the novel metal-based anticancer agents NAMI-A and AP 5280

    NARCIS (Netherlands)

    Bouma, M. (Marjan)

    2002-01-01

    The pharmaceutical development of the two novel metal-based anticancer agents NAMI-A and AP 5280 is described in this thesis, starting with the development of analytical methods for the quality control of drug substance and final product, via the formulation process leading to a stable, intravenous

  4. Non-newtonian deformation of co-based metallic glass at low stresses

    NARCIS (Netherlands)

    Fursova, YV; Khonik, VA; Csach, K; Ocelik, Vaclav

    2000-01-01

    The results of precision measurements of creep in Co-based metallic glass are presented. It is shown that, in spite of generally accepted concepts, plastic flow at low stresses under intense structural relaxation conditions is of a non-Newtonian type. Consequences of this fact are considered. (C)

  5. Emerging protein targets for metal-based pharmaceutical agents : An update

    NARCIS (Netherlands)

    de Almeida, Andreia; Oliveira, Bruno L.; Correia, Joao D. G.; Soveral, Graca; Casini, Angela

    2013-01-01

    The peculiar chemical properties of metal-based drugs impart innovative pharmacological profiles to this class of therapeutic and diagnostic agents, most likely in relation to novel molecular mechanisms still poorly understood. However, inorganic drugs have been scarcely considered for medicinal

  6. Metal-based nanoparticles in soil: Fate, behaviour, and effects on soil invertebrates.

    NARCIS (Netherlands)

    Tourinho, P.S.; van Gestel, C.A.M.; Lofts, S.; Svendsen, C.; Soares, A.M.V.M.; Loureiro, S.

    2012-01-01

    Metal-based nanoparticles (NPs) (e.g., silver, zinc oxide, titanium dioxide, iron oxide) are being widely used in the nanotechnology industry. Because of the release of particles from NP-containing products, it is likely that NPs will enter the soil compartment, especially through land application

  7. Calculating the Entropy of Solid and Liquid Metals, Based on Acoustic Data

    Science.gov (United States)

    Tekuchev, V. V.; Kalinkin, D. P.; Ivanova, I. V.

    2018-05-01

    The entropies of iron, cobalt, rhodium, and platinum are studied for the first time, based on acoustic data and using the Debye theory and rigid-sphere model, from 298 K up to the boiling point. A formula for the melting entropy of metals is validated. Good agreement between the research results and the literature data is obtained.

  8. Evaluation of fatigue crack growth rate for iron-carbon metals based ...

    African Journals Online (AJOL)

    Evaluation of fatigue crack growth rate for iron-carbon metals based on degradation-entropy generation theorem. R Idris, S Abdullah, P Thamburaja, M.Z. Omar. Abstract. No Abstract. Keywords: degradation-entropy generation theorem; entropy generation; fatigue crack growth rate; tempered Fe-C steel. Full Text:.

  9. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    2014-01-01

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  10. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  11. Theoretical evaluation on selective adsorption characteristics of alkali metal-based sorbents for gaseous oxidized mercury.

    Science.gov (United States)

    Tang, Hongjian; Duan, Yufeng; Zhu, Chun; Cai, Tianyi; Li, Chunfeng; Cai, Liang

    2017-10-01

    Alkali metal-based sorbents are potential for oxidized mercury (Hg 2+ ) selective adsorption but show hardly effect to elemental mercury (Hg 0 ) in flue gas. Density functional theory (DFT) was employed to investigate the Hg 0 and HgCl 2 adsorption mechanism over alkali metal-based sorbents, including calcium oxide (CaO), magnesium oxide (MgO), potassium chloride (KCl) and sodium chloride (NaCl). Hg 0 was found to weakly interact with CaO (001), MgO (001), KCl (001) and NaCl (001) surfaces while HgCl 2 was effectively adsorbed on top-O and top-Cl sites. Charge transfer and bond population were calculated to discuss the covalency and ionicity of HgCl 2 bonding with the adsorption sites. The partial density of states (PDOS) analysis manifests that HgCl 2 strongly interacts with surface sites through the orbital hybridizations between Hg and top O or Cl. Frontier molecular orbital (FMO) energy and Mulliken electronegativity are introduced as the quantitative criteria to evaluate the reactivity of mercury species and alkali metal-based sorbents. HgCl 2 is identified as a Lewis acid and more reactive than Hg 0 . The Lewis basicity of the four alkali metal-based sorbents is predicted as the increasing order: NaCl < MgO < KCl < CaO, in consistence with the trend of HgCl 2 adsorption energies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Wear behaviour of Zr-based in situ bulk metallic glass matrix ...

    Indian Academy of Sciences (India)

    Zr-based bulk metallic glass (BMG) and its in situ BMG matrix composites with diameter of 3 mm were fabricated by conventional .... with no evidence of any crystalline Bragg peaks, indicating that the as-cast sample is fully ..... Acknowledgements. Funding by education fund item of Liaoning Province under grant no.

  13. Sensing of polymeric sensor-based rhodamine B derivative for metal ...

    Indian Academy of Sciences (India)

    ity after complexes with metal ions by activating a carbonyl group in a spirolactone or a spirolactam moiety [27–30]. The mechanism is based on the switch off/on of the spirocyclic moiety mediated by guests. In general, spirolactam formation of rhodamine derivatives is non-fluorescent, whereas its ring-opened amide system ...

  14. Certain relationships in the luminescence of organophosphors based on metal complexes

    International Nuclear Information System (INIS)

    Zel'tser, L.E.; Talipov, S.T.; Vereshchagina, N.G.

    1986-01-01

    A study has been made of general relationships in the luminescent radiation of organophosphors based on metal complexes and the specific features of chemical and analytical properties of organic analytical reagents in the electronically excited state. Routes have been proposed for activation of emission and for the improvement of metrological characteristics of the luminescence method of analysis

  15. Porphyrin-Based Metal-Organic Frameworks as Heterogeneous Catalysts in Oxidation Reactions

    Directory of Open Access Journals (Sweden)

    Carla F. Pereira

    2016-10-01

    Full Text Available Porphyrin-based Metal-Organic Frameworks (Por-MOFs constitute a special branch of the wide MOF family that has proven its own value and high potential in different applications. In this mini-review the application of these materials as catalysts in oxidation reactions is highlighted.

  16. Lanthanide-Based Metal Organic Frameworks: Synthetic Strategies and Catalytic Applications

    NARCIS (Netherlands)

    Pagis, C.; Ferbinteanu, M.; Rothenberg, G.; Grecea, S.

    2016-01-01

    This short critical review outlines the main synthetic strategies used in the designed synthesis of lanthanide-based metal organic frameworks (Ln-MOFs). It explains the impact of the choice of organic linker on the final network topology, and it highlights the applications of Ln-MOFs in the

  17. Base-oxidant promoted metal-free N-demethylation of arylamines

    Indian Academy of Sciences (India)

    A metal-free oxidative N-demethylation of arylamines with triethylamine as a base and tert-butyl hydroperoxide (TBHP) as oxidant is reported in this paper. The reaction is general, practical, inexpensive, non-toxic, and the method followed is environmentally benign, with moderate to good yields.

  18. Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures (TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties.

    Science.gov (United States)

    Tang, Jianbo; Zhao, Xi; Li, Jing; Guo, Rui; Zhou, Yuan; Liu, Jing

    2017-10-18

    Metals are excellent choices for electrical- and thermal-current conducting. However, either the stiffness of solid metals or the fluidity of liquid metals could be troublesome when flexibility and formability are both desired. To address this problem, a reliable two-stage route to improve the functionalities of gallium-based liquid metals is proposed. A series of stable semiliquid/semisolid gallium-based liquid metal amalgams with well-controlled particle packing ratios, which we call TransM 2 ixes, are prepared and characterized. Through effectively packing the liquid metal with copper particles (which are found to turn into intermetallic compound, CuGa 2 , after dispersing), remarkable enhancements in electrical conductivity (6 × 10 6 S m -1 , ∼80% increase) and thermal conductivity (50 W m -1 K -1 , ∼100% increase) are obtained, making the TransM 2 ixes stand out from current conductive soft materials. The TransM 2 ixes also exhibit appealing semiliquid/semisolid mechanical behaviors such as excellent adhesion, tunable formability, and self-healing ability. As a class of highly conductive yet editable metallic mixtures, the TransM 2 ixes demonstrate potential applications in fields like printed and/or flexible electronics and thermal interface materials, as well as other circumstances where the flexibility and conductivity of interfaces and connections are crucial.

  19. Economizer Based Data Center Liquid Cooling with Advanced Metal Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Timothy Chainer

    2012-11-30

    A new chiller-less data center liquid cooling system utilizing the outside air environment has been shown to achieve up to 90% reduction in cooling energy compared to traditional chiller based data center cooling systems. The system removes heat from Volume servers inside a Sealed Rack and transports the heat using a liquid loop to an Outdoor Heat Exchanger which rejects the heat to the outdoor ambient environment. The servers in the rack are cooled using a hybrid cooling system by removing the majority of the heat generated by the processors and memory by direct thermal conduction using coldplates and the heat generated by the remaining components using forced air convection to an air- to- liquid heat exchanger inside the Sealed Rack. The anticipated benefits of such energy-centric configurations are significant energy savings at the data center level. When compared to a traditional 10 MW data center, which typically uses 25% of its total data center energy consumption for cooling this technology could potentially enable a cost savings of up to $800,000-$2,200,000/year (assuming electricity costs of 4 to 11 cents per kilowatt-hour) through the reduction in electrical energy usage.

  20. Plasma-implantation-based surface modification of metals with single-implantation mode

    Science.gov (United States)

    Tian, X. B.; Cui, J. T.; Yang, S. Q.; Fu, Ricky K. Y.; Chu, Paul K.

    2004-12-01

    Plasma ion implantation has proven to be an effective surface modification technique. Its biggest advantage is the capability to treat the objects with irregular shapes without complex manipulation of target holder. Many metal materials such as aluminum, stainless steel, tool steel, titanium, magnesium etc, has been treated using this technique to improve their wear-resistance, corrosion-resistance, fatigue-resistance, oxidation-resistance, bio-compatiblity etc. However in order to achieve thicker modified layers, hybrid processes combining plasma ion implantation with other techniques have been frequently employed. In this paper plasma implantation based surface modification of metals using single-implantation mode is reviewed.

  1. Friction and surface chemistry of some ferrous-base metallic glasses

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The friction properties of some ferrous-base metallic glasses were measured both in argon and in vacuum to a temperature of 350 C. The alloy surfaces were also analyzed with X-ray photoelectron spectroscopy to identify the compounds and elements present on the surface. The results of the investigation indicate that even when the surfaces of the amorphous alloys, or metallic glasses, are atomically clean, bulk contaminants such as boric oxide and silicon dioxide diffuse to the surfaces. Friction measurements in both argon and vacuum indicate that the alloys exhibit higher coefficients of friction in the crystalline state than they do in the amorphous state.

  2. Hot metal temperature prediction in blast furnace using advanced model based on fuzzy logic tools

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.D.; Obeso, F.; Mochon, J.; Barea, R.; Jimenez, J.

    2007-05-15

    The present work presents a model based on fuzzy logic tools to predict and simulate the hot metal temperature in a blast furnace (BF). As input variables this model uses the control variables of a current BF such as moisture, pulverised coal injection, oxygen addition, mineral/coke ratio and blast volume, and it yields as a result of the hot metal temperature. The variables employed to develop the model have been obtained from data supplied by current sensors of a Spanish BF In the model training stage the adaptive neurofuzzy inference system and the subtractive clustering algorithms have been used.

  3. Superhydrophobic Zr-based metallic glass surface with high adhesive force

    Science.gov (United States)

    Li, Ning; Xia, Ting; Heng, Liping; Liu, Lin

    2013-06-01

    Micro/nano hierarchical structures were constructed on Zr35Ti30Be26.75Cu8.25 metallic glass surface by silicon moulding and subsequently chemical etching. The as-formed surface exhibited both superhydrophobicity and high adhesive force towards water. The superhydrophobicity is rationalized based on the modified Cassie-Baxter model [A. B. D. Cassie and S. Baxter, Trans. Faraday Soc. 40, 546 (1944)]. The origin of the robust adhesion is described in terms of intermolecular capillary forces. The present results not only provide a method to fabricate superhydrophobic metallic glasses surface but also explore an important industrial application as dry adhesives and transport of liquid microdroplets.

  4. Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

    KAUST Repository

    Al-ShaikhAli, Anaam H.

    2016-11-30

    Liquid organic chemical hydride is a promising candidate for hydrogen storage and transport. Methylcyclohexane (MCH) to toluene (TOL) cycle has been considered as one of the feasible hydrogen carrier systems, but selective dehydrogenation of MCH to TOL has only been achieved using the noble Pt-based catalysts. The aim of this study is to develop non-noble, cost-effective metal catalysts that can show excellent catalytic performance, mainly maintaining high TOL selectivity achievable by Pt based catalysts. Mono-metallic Ni based catalyst is a well-known dehydrogenation catalyst, but the major drawback with Ni is its hydrogenolysis activity to cleave C-C bonds, which leads to inferior selectivity towards dehydrogenation of MCH to TOL. This study elucidate addition of the second metal to Ni based catalyst to improve the TOL selectivity. Herein, ubiquitous bi-metallic nanoparticles catalysts were investigated including (Ni–M, M: Ag, Zn, Sn or In) based catalysts. Among the catalysts investigated, the high TOL selectivity (> 99%) at low conversions was achieved effectively using the supported NiZn catalyst under flow of excess H2. In this work, a combined study of experimental and computational approaches was conducted to determine the main role of Zn over Ni based catalyst in promoting the TOL selectivity. A kinetic study using mono- and bimetallic Ni based catalysts was conducted to elucidate reaction mechanism and site requirement for MCH dehydrogenation reaction. The impact of different reaction conditions (feed compositions, temperature, space velocity and stability) and catalyst properties were evaluated. This study elucidates a distinctive mechanism of MCH dehydrogenation to TOL reaction over the Ni-based catalysts. Distinctive from Pt catalyst, a nearly positive half order with respect to H2 pressure was obtained for mono- and bi-metallic Ni based catalysts. This kinetic data was consistent with rate determining step as (somewhat paradoxically) hydrogenation

  5. NHC–metal complexes based on benzimidazolium moiety for chemical transformation

    Directory of Open Access Journals (Sweden)

    Prashant Narayan Muskawar

    2016-11-01

    Full Text Available N-heterocyclic carbenes (NHC are now commonly encountered in organometallic and inorganic coordination chemistry because of its environmental friendly nature as solvent and catalyst, high activity, selectivity and easily recovered materials that were used to replace the traditional volatile organic solvents which generally suffered from environmental problems. Benzimidazole based ionic liquids (BILs offering a new possibility for developing environmentally-friendly basic catalyst with transition metal and non-transition metal (Ag, Au, Ru, Rh, Fe, Co, Cu, Cd and Pd. They are flexible, nonvolatile, noncorrosive and immiscible with many organic solvents. In this review, we wish to present an overview of the preparation and applications in various reactions like alkylation, arylation, etherification, benzoin reaction, aldol condensation and metal mediated catalyst in Suzuki, Suzuki–Miyaura, Heck cross coupling and reduction, also in electrochemical application (electrocatalyst, anion sensor, solar cell, proton conduction, malaria parasite, antimicrobial activity, etc.

  6. Springback prediction in sheet metal forming process based on the hybrid SA

    International Nuclear Information System (INIS)

    Guo Yuqin; Jiang Hong; Wang Xiaochun; Li Fuzhu

    2005-01-01

    In terms of the intensive similarity between the sheet metal forming-springback process and that of the annealing of metals, it is suggested that the simulation of the sheet metal forming process is performed with the Nonlinear FEM and the springback prediction is implemented by solving the large-scale combinational optimum problem established on the base of the energy descending and balancing in deformed part. The BFGS-SA hybrid SA approach is proposed to solve this problem and improve the computing efficiency of the traditional SA and its capability of obtaining the global optimum solution. At the same time, the correlative annealing strategies for the SA algorithm are determined in here. By comparing the calculation results of sample part with those of experiment measurement at the specified sections, the rationality of the schedule of springback prediction used and the validity of the BFGS-SA algorithm proposed are verified

  7. Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines

    Science.gov (United States)

    Costa, Susana P. G.; Oliveira, Elisabete; Lodeiro, Carlos; Raposo, M. Manuela M.

    2007-01-01

    The synthesis of new fluorescent probes containing the thiophene and benzoxazole moieties combined with an alanine residue is described. The resulting highly fluorescent heterocyclic alanine derivatives respond via a quenching effect, with paramagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by the absorption and steady-state fluorescence spectroscopy studies. The formation of mononuclear or dinuclear metal complexes was postulated based on the presence of the free carboxylic acid as binding site and also with the interaction with the donor atoms in the chromophore. Interaction with other important biological metal ions such as Zn(II), Ca(II) and Na(I) was also explored. PMID:28903216

  8. Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases.

    Science.gov (United States)

    Pawar, Vijay; Naik, Prashant; Giridhar, Rajani; Yadav, Mange Ram

    2015-01-01

    In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanolamine, and diethylamine) had lowered melting points while the alkali metal salt (sodium) had a higher melting point than BPA. The in vitro study showed that salt formation improves the physicochemical properties of BPA, leading to improved permeability through the skin. Amongst all the prepared salts, ethanolamine salt (1b) showed 7.2- and 5.4-fold higher skin permeation than the parent drug at pH 7.4 and 5.0, respectively, using rat skin.

  9. Magnetic nanoparticle based solid-phase extraction of heavy metal ions: A review on recent advances.

    Science.gov (United States)

    Hemmati, Maryam; Rajabi, Maryam; Asghari, Alireza

    2018-02-06

    This review (with 151 refs) focuses on recent progress that has been made in magnetic nanoparticle-based solid phase extraction (SPE), pre-concentration and speciation of heavy metal ions. In addition, it discusses applications to complex real samples such as environmental, food, and biological matrices. The introduction addresses current obstacles and limitations associated with established SPE approaches and discusses the present state of the art in different formats of off-line and on-line SPE. The next section covers magnetized inorganic nanomaterials for use in SPE, with subsections on magnetic silica, magnetic alumina and titania, and on magnetic layered double oxides. A further section treats magnetized carbonaceous nanomaterials for use in SPE, with subsections on magnetic graphene and/or graphene oxides, magnetic carbon nanotubes and magnetic carbon nitrides. We then discuss the progress made in SPE based on the use of magnetized organic polymers (mainly non-imprinted and ion-imprinted polymer). This is followed by shorter sections on the use of magnetized metal organic frameworks, magnetized ionic liquids and magnetized biosorbents. All sections include discussions of the nanomaterials in terms of selectivity, sorption capacity, mechanisms of sorption and common routes for material synthesis. A concluding section addresses actual challenges and discusses perspective routes towards further improvements. Graphical abstract An overview on booster nanomaterials (ionic liquids, inorganic, organic and biological materials, and metal-organic frameworks) for use in magnetic nanoparticle-based solid-phase extraction of heavy metal ions.

  10. Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base.

    Science.gov (United States)

    Abu Al-Nasr, Ahmad K; Ramadan, Ramadan M

    2013-03-15

    Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H(2)O)(4)](NO(3))(3), M=Cr(III) and Fe(III), [NiL(H(2)O)(4)](NO(3))(2), [ML(H(2)O)(2)](NO(3))(2), M=Zn(II) and Cd(II), [Cl(2)Pd(μ-Cl)(2)PdL], [PtL(Cl)(2)] and [PtL(Cl)(4)] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and (1)H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)(2)] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2). Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base

    Science.gov (United States)

    Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

    2013-03-01

    Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H2O)4](NO3)3, M = Cr(III) and Fe(III), [NiL(H2O)4](NO3)2, [ML(H2O)2](NO3)2, M = Zn(II) and Cd(II), [Cl2Pd(μ-Cl)2PdL], [PtL(Cl)2] and [PtL(Cl)4] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)2] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2).

  12. Standardized hydrogen storage module with high utilization factor based on metal hydride-graphite composites

    OpenAIRE

    Bürger, Inga; Dieterich, Mila; Pohlmann, Carsten; Röntzsch, Lars; Linder, Marc

    2017-01-01

    In view of hydrogen based backup power systems or small-scale power2gas units, hydrogen storages based on metal hydrides offer a safe and reliable solution. By using Hydralloy C5 as suitable hydride forming alloy, the present tank design guarantees very simple operating conditions: pressures between 4 bar and 30 bar, temperatures between 15 C and 40 C and minimal efforts for thermal management in combination with fast and constant charging and discharging capabilities. The modular...

  13. Structure vs chemistry: friction and wear of Pt-based metallic surfaces.

    Science.gov (United States)

    Caron, A; Louzguine-Luzguin, D V; Bennewitz, R

    2013-11-13

    In comparison of a Pt57.5Cu14.7Ni5.3P22.5 metallic glass with a Pt(111) single crystal we find that wearless friction is determined by chemistry through bond formation alloying, while wear is determined by structure through plasticity mechanisms. In the wearless regime, friction is affected by the chemical composition of the counter body and involves the formation of a liquid-like neck and interfacial alloying. The wear behavior of Pt-based metallic surfaces is determined by their structural properties and corresponding mechanisms for plastic deformation. In the case of Pt(111) wear occurs by dislocation-mediated homogeneous plastic deformation. In contrast the wear of Pt57.5Cu14.7Ni5.3P22.5 metallic glass occurs through localized plastic deformation in shear bands that merge together in a single shear zone above a critical load and corresponds to the shear softening of metallic glasses. These results open a new route in the control of friction and wear of metals and are relevant for the development of self-lubricated and wear-resistant mechanical devices.

  14. Flexible strain sensors with high performance based on metallic glass thin film

    Science.gov (United States)

    Xian, H. J.; Cao, C. R.; Shi, J. A.; Zhu, X. S.; Hu, Y. C.; Huang, Y. F.; Meng, S.; Gu, L.; Liu, Y. H.; Bai, H. Y.; Wang, W. H.

    2017-09-01

    Searching strain sensitive materials for electronic skin is of crucial significance because of the restrictions of current materials such as poor electrical conductivity, large energy consumption, complex manufacturing process, and high cost. Here, we report a flexible strain sensor based on the Zr55Cu30Ni5Al10 metallic glass thin film which we name metallic glass skin. The metallic glass skin, synthesized by ion beam deposition, exhibits piezoresistance effects with a gauge factor of around 2.86, a large detectable strain range (˜1% or 180° bending angle), and good conductivity. Compared to other e-skin materials, the temperature coefficient of resistance of the metallic glass skin is extremely low (9.04 × 10-6 K-1), which is essential for the reduction in thermal drift. In addition, the metallic glass skin exhibits distinct antibacterial behavior desired for medical applications, also excellent reproducibility and repeatability (over 1000 times), nearly perfect linearity, low manufacturing cost, and negligible energy consumption, all of which are required for electronic skin for practical applications.

  15. Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels

    Directory of Open Access Journals (Sweden)

    Subramanian B

    2015-10-01

    Full Text Available Balasubramanian Subramanian,1 Sundaram Maruthamuthu,2 Senthilperumal Thanka Rajan1 1Electrochemical Material Science Division, 2Corrosion and Materials Protection Division, Central Electrochemical Research Institute, Karaikudi, India Abstract: Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.% of approximately 1.5 µm and 3 µm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature. Keywords: thin film metallic glasses, sputtering, biocompatibility, corrosion, antimicrobial activity

  16. Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes

    Science.gov (United States)

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-01

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation.

  17. Fluorescence array-based sensing of metal ions using conjugated polyelectrolytes.

    Science.gov (United States)

    Wu, Yi; Tan, Ying; Wu, Jiatao; Chen, Shangying; Chen, Yu Zong; Zhou, Xinwen; Jiang, Yuyang; Tan, Chunyan

    2015-04-01

    Array-based sensing offers several advantages for detecting a series of analytes with common structures or properties. In this study, four anionic conjugated polyelectrolytes (CPEs) with a common poly(p-pheynylene ethynylene) (PPE) backbone and varying pendant ionic side chains were designed. The conjugation length, repeat unit pattern, and ionic side chain composition were the main factors affecting the fluorescence patterns of CPE polymers in response to the addition of different metal ions. Eight metal ions, including Pb(2+), Hg(2+), Fe(3+), Cr(3+), Cu(2+), Mn(2+), Ni(2+), and Co(2+), categorized as water contaminants by the Environmental Protection Agency, were selected as analytes in this study. Fluorescence intensity response patterns of the four-PPE sensor array toward each of the metal ions were recorded, analyzed, and transformed into canonical scores using linear discrimination analysis (LDA), which permitted clear differentiation between metal ions using both two-dimensional and three-dimensional graphs. In particular, the array could readily differentiate between eight toxic metal ions in separate aqueous solutions at 100 nM. Our four-PPE sensor array also provides a practical application to quantify Pb(2+) and Hg(2+) concentrations in blind samples within a specific concentration range.

  18. Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

    Science.gov (United States)

    Blasco-Ahicart, Marta; Soriano-López, Joaquín; Carbó, Jorge J.; Poblet, Josep M.; Galan-Mascaros, J. R.

    2018-01-01

    Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm-2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

  19. Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

    International Nuclear Information System (INIS)

    Raja, Mohan; Shanmugharaj, A.M.; Ryu, Sung Hun; Subha, J.

    2011-01-01

    Highlights: → Polyurethane based on pristine and metal (Ag and Cu) nanoparticle decorated CNTs nanocomposites are prepared through melt blending process. → The electrical, mechanical, dynamic mechanical, thermal conductivity and electro active shape memory properties of the PU nanocomposites were investigated. → The influence of metal nanoparticle decorated CNTs showed significant improvement in their all properties to compare to pristine CNTs. → Electro active shape memory studies of the PU/M-CNTs nanocomposites reveal extraordinary recoverability of its shape at lower applied dc voltages. - Abstract: Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.

  20. Synthesis and heavy metal immobilization behaviors of fly ash based geopolymer

    Energy Technology Data Exchange (ETDEWEB)

    Yunsheng Zhang; Wei Sun; Wei She; Guowei Sun [Southeast University, Nanjing (China). Jiangsu Civil Engineering Materials Key Laboratory

    2009-10-15

    Two aspects of studies were carried out: 1) synthesis of geopolymer by using fly ash and metakaolin; 2) Immobilization behaviors of fly ash based geopolymer in a presence of Pb and Cu ions. As for the synthesis of fly ash based geopolymer, 4 different fly ash content (10%, 30%, 50%, 70%) and 3 types of curing regimes (standard curing, steam curing and autoclave curing) were investigated to obtain the optimum synthesis condition based on the compressive and flexural strength. The experimental results show that geopolymer, containing 30% fly ash and synthesized at steam curing (80{sup o}C for 8 h), exhibits higher mechanical strengths. The compressive and flexural strengths of fly ash based geopolymer reach 32.2 MPa and 7.15 MPa, respectively. Additionally, Infrared (IR) and X-ray diffraction (XRD) techniques were used to characterize the microstructure of the fly ash geopolymer. IR spectra shows that the absorptive band at 1086 cm{sup -1} shifts to lower wave number around 1033 cm{sup -1}, and the 6-coordinated Al transforms into 4-coordination during the synthesis of fly ash based geopolymer. The resulting geopolymeric products were X-ray amorphous materials. As for immobilization of heavy metals, leaching tests were employed to investigate the immobilization behaviors of the fly ash based geopolymer synthesized under the above optimum condition. The leaching tests showed that fly ash based geopolymer can effectively immobilize Cu and Pb heavy metal ions, and the immobilization efficiency reached 90% greater when heavy metals were incorporated in the fly ash geopolymer in the range of 0.1% to 0.3%. The Pb exhibits better immobilization efficiency than the Cu, especially in the case of large dosages of heavy metals.

  1. Improved image quality in abdominal CT in patients who underwent treatment for hepatocellular carcinoma with small metal implants using a raw data-based metal artifact reduction algorithm.

    Science.gov (United States)

    Sofue, Keitaro; Yoshikawa, Takeshi; Ohno, Yoshiharu; Negi, Noriyuki; Inokawa, Hiroyasu; Sugihara, Naoki; Sugimura, Kazuro

    2017-07-01

    To determine the value of a raw data-based metal artifact reduction (SEMAR) algorithm for image quality improvement in abdominal CT for patients with small metal implants. Fifty-eight patients with small metal implants (3-15 mm in size) who underwent treatment for hepatocellular carcinoma were imaged with CT. CT data were reconstructed by filtered back projection with and without SEMAR algorithm in axial and coronal planes. To evaluate metal artefact reduction, mean CT number (HU and SD) and artefact index (AI) values within the liver were calculated. Two readers independently evaluated image quality of the liver and pancreas and visualization of vasculature using a 5-point visual score. HU and AI values and image quality on images with and without SEMAR were compared using the paired Student's t-test and Wilcoxon signed rank test. Interobserver agreement was evaluated using linear-weighted κ test. Mean HU and AI on images with SEMAR was significantly lower than those without SEMAR (P small metal implants by reducing metallic artefacts. • SEMAR algorithm significantly reduces metallic artefacts from small implants in abdominal CT. • SEMAR can improve image quality of the liver in dynamic CECT. • Confidence visualization of hepatic vascular anatomies can also be improved by SEMAR.

  2. A multi-metal risk assessment strategy for natural freshwater ecosystems based on the additive inhibitory free metal ion concentration index.

    Science.gov (United States)

    Alves, Cristina M; Ferreira, Carlos M H; Soares, Eduardo V; Soares, Helena M V M

    2017-04-01

    Scientifically sound risk assessment strategies and derivations of environmental quality standards for metals present in freshwater environments are currently hampered by insufficient chronic toxicity data collected from natural ecosystems, as well as inadequate information on metal speciation. Thus, the aim of the present study was to evaluate the impact of freshwater containing multiple metals (Cd, Cr, Cu, Ni, Pb and Zn) on the chronic toxicity (72h) to the alga Pseudokirchneriella subcapitata and compare the observed toxicity results to the total and free metal concentration of the samples. Based on the information obtained herein, an additive inhibitory free multi-metal ion concentration index, calculated as the sum of the equivalent toxicities to the free metal ion concentration of each sample, was developed. The proposed index was well correlated to the observed chronic toxicity results, indicating that the concentration addition, when expressed as the free-ion activity, can be considered a reliable indicator for the evaluation of ecological risk assessments for natural waters containing multiple metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    Science.gov (United States)

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  4. A 1-dodecanethiol-based phase transfer protocol for the highly efficient extraction of noble metal ions from aqueous phase.

    Science.gov (United States)

    Chen, Dong; Cui, Penglei; Cao, Hongbin; Yang, Jun

    2015-03-01

    A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an ethanolic solution of 1-dodecanethiol, and then extracting the coordination compounds formed between noble metal ions and 1-dodecanethiol into a non-polar organic solvent. A number of characterization techniques, including inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis demonstrate that this protocol could be applied to extract a wide variety of noble metal ions from water to dichloromethane with an efficiency of >96%, and has high selectivity for the separation of the noble metal ions from other transition metals. It is therefore an attractive alternative for the extraction of noble metals from water, soil, or waste printed circuit boards. Copyright © 2015. Published by Elsevier B.V.

  5. Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2015-09-01

    Full Text Available This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.

  6. Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

    Science.gov (United States)

    Ley, Morten B.; Meggouh, Mariem; Moury, Romain; Peinecke, Kateryna; Felderhoff, Michael

    2015-01-01

    This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM) fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability. PMID:28793541

  7. A review on versatile applications of transition metal complexes incorporating Schiff bases

    Directory of Open Access Journals (Sweden)

    Ahmed M. Abu-Dief

    2015-06-01

    Full Text Available Schiff bases and their complexes are versatile compounds synthesized from the condensation of an amino compound with carbonyl compounds and widely used for industrial purposes and also exhibit a broad range of biological activities including antifungal, antibacterial, antimalarial, antiproliferative, anti-inflammatory, antiviral, and antipyretic properties. Many Schiff base complexes show excellent catalytic activity in various reactions and in the presence of moisture. Over the past few years, there have been many reports on their applications in homogeneous and heterogeneous catalysis. The high thermal and moisture stabilities of many Schiff base complexes were useful attributes for their application as catalysts in reactions involving at high temperatures. The activity is usually increased by complexation therefore to understand the properties of both ligands and metal can lead to the synthesis of highly active compounds. The influence of certain metals on the biological activity of these compounds and their intrinsic chemical interest as multidentate ligands has prompted a considerable increase in the study of their coordination behaviour. Development of a new chemotherapeutic Schiff bases and their metal complexes is now attracting the attention of medicinal chemists. This review compiles examples of the most promising applied Schiff bases and their complexes in different areas.

  8. Tailoring the optical properties of wide-bandgap based microcavities via metal films

    Energy Technology Data Exchange (ETDEWEB)

    Sebald, K., E-mail: ksebald@ifp.uni-bremen.de; Rahman, SK. S.; Cornelius, M.; Gutowski, J. [Semiconductor Optics, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klein, T.; Klembt, S.; Kruse, C.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany)

    2015-08-10

    We report on the tuning of the optical properties of II-VI-material-based microcavity samples, which is achieved by depositing Ag films on top of the structures. The micro-reflectivity spectra show a spectral shift of the sample resonance dependent on the metal layer thickness. By comparison of the experimental findings with the theoretical calculations applying the transfer matrix method on a metal-dielectric mirror structure, the influence of the metal layer particularly with regard to its partial oxidation was explored. Tamm plasmon modes are created at the interface between an open cavity with three ZnSe quantum wells and a metal layer on top. When tuning the excitonic emission relative to the mode by changing the sample temperature, an anticrossing of the resonances was observed. This is a clear indication that the strong coupling regime has been achieved in that sample configuration yielding a Rabi splitting of 18.5 meV. These results are promising for the realization of polariton-based optical devices with a rather simple sample configuration.

  9. Synthesis, characterization, biological and electrical conductivity studies of some Schiff base metal complexes

    Directory of Open Access Journals (Sweden)

    A. R. Yaul

    2014-05-01

    Full Text Available Metal complexes of VO(IV, Zr(IV, Th(IV and UO2(VI with Schiff base ligands derived from 4-nitrobenzoylhydrazide with 2-hydroxy-5-methylacetophenone (H2L1 or 2-hydroxy-5-chloroacetophenone (H2L2 have been prepared. All the complexes have been characterized on the basis of elemental analyses, magnetic susceptibility measurement, electronic and IR spectra and thermogravimetric analysis. The IR spectral data suggested that the ligands behave as dibasic tridentate moiety towards the central metal ion coordinating through phenolic oxygen, enolic oxygen and azomethine nitrogen atoms. The elemental analyses show a 1:1 metal:ligand stoichiometry for all the complexes except Th(IV which has 1:2 stoichiometry. The thermal analysis evidenced that thermal transformations of complexes are processes according to TG curves including dehydration, thermolysis and oxidative degradation of Schiff base. The final product of decomposition is the most stable metallic oxide. The kinetic analysis of the thermogravimetric data was performed by using the Coats-Redfern method. Solid state electrical conductivity of the complexes has been measured in their compressed pellet form over a 310-413 K temperature range. All the complexes show semiconducting behavior as their conductivity increases with increasing temperature and a function of ionic size. All the complexes along with ligands were also screened for their antibacterial and antifungal activities. DOI: http://dx.doi.org/10.4314/bcse.v28i2.9

  10. Stability and Activity of Non-Noble-Metal-Based Catalysts Toward the Hydrogen Evolution Reaction.

    Science.gov (United States)

    Ledendecker, Marc; Mondschein, Jared S; Kasian, Olga; Geiger, Simon; Göhl, Daniel; Schalenbach, Max; Zeradjanin, Aleksandar; Cherevko, Serhiy; Schaak, Raymond E; Mayrhofer, Karl

    2017-08-07

    A fundamental understanding of the behavior of non-noble based materials toward the hydrogen evolution reaction is crucial for the successful implementation into practical devices. Through the implementation of a highly sensitive inductively coupled plasma mass spectrometer coupled to a scanning flow cell, the activity and stability of non-noble electrocatalysts is presented. The studied catalysts comprise a range of compositions, including metal carbides (WC), sulfides (MoS 2 ), phosphides (Ni 5 P 4 , Co 2 P), and their base metals (W, Ni, Mo, Co); their activity, stability, and degradation behavior was elaborated and compared to the state-of-the-art catalyst platinum. The non-noble materials are stable at HER potentials but dissolve substantially when no current is flowing. Through pre- and post-characterization of the catalysts, explanations of their stability (thermodynamics and kinetics) are discussed, challenges for the application in real devices are analyzed, and strategies for circumventing dissolution are suggested. The precise correlation of metal dissolution with applied potential/current density allows for narrowing down suitable material choices as replacement for precious group metals as for example, platinum and opens up new ways in finding cost-efficient, active, and stable new-generation electrocatalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Comparative study of ceramometal tensile bonding strength in two base metal alloys

    Directory of Open Access Journals (Sweden)

    Comparative study of ceramometal tensile bonding strength in two base metal alloys

    2005-06-01

    Full Text Available Statement of Problem: One of the greatest problems in metal –ceramic restorations is debonding of porcelain from dental alloys. Production of dental alloys by Iranian companies necessitates the evaluation of physical and handling properties of these products. Purpose: In this study the bond strength between porcelain and two types of base metal alloys, Supercast (with beryllium and Minalux (without beryllium was investigated. Materials and Methods: In this experimental study 10 cylindric bars from each base metal alloy were prepared. The bars were degassed and porcelain was applied around them in a disc form (8 mm diameter and 2 mm thickness. The bond strength of porcelain to metal bars was tested with the shear strength test by Instron. Data were analyzed with student t-test and P<0.05 was considered as the limit of significance. Results: The mean failure load was 71.58±6.4 KgF for Supercast and 67.34±5.48 for Minalux alloy. The bond strength of Supercast and Minalux were 55.85±4.99 MPa and 52.54±4.27 MPa respectively. The difference was statistically significant (P0.001. Conclusions: This study showed that nickel-chromium-beryllium alloy (Supercast produced significantly better ceramometal bonding than nickel chromium alloy without beryllium (Minalux.

  12. Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ping; Guliaev, Anton B.; Hang, Bo

    2006-02-28

    Cadmium (Cd{sup 2+}), nickel (Ni{sup 2+}) and cobalt (Co{sup 2+}) are human and/or animal carcinogens. Zinc (Zn{sup 2+}) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (var epsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1000 {micro}M, both Cd{sup 2+} and Zn{sup 2+} showed metal-dependent inhibition of the MPG catalytic activity. Ni{sup 2+} also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co{sup 2+} and Mg{sup 2+} did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the var epsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd{sup 2+}, Zn{sup 2+}, and Ni{sup 2+} at concentrations that show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn{sup 2+} showed that the MPG active site has a potential binding site for Zn{sup 2+}, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.

  13. Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection

    Directory of Open Access Journals (Sweden)

    Kwangjae Lee

    2017-02-01

    Full Text Available A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD technique is used to make the highly porous structure such as nanocolumns (NCs of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO2, WO3 and In2O3 NCs is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides (PVC decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C, the resistances of the metal-oxide NCs are abruptly changed and SnO2 NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C. The response time of SnO2 NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection.

  14. Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection.

    Science.gov (United States)

    Lee, Kwangjae; Shim, Young-Seok; Song, Young Geun; Han, Soo Deok; Lee, Youn-Sung; Kang, Chong-Yun

    2017-02-07

    A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique is used to make the highly porous structure such as nanocolumns (NCs) of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO₂, WO₃ and In₂O₃ NCs) is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides) (PVC) decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C), the resistances of the metal-oxide NCs are abruptly changed and SnO₂ NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p -type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C). The response time of SnO₂ NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection.

  15. Simultaneous and integrated neutron-based techniques for material analysis of a metallic ancient flute

    Science.gov (United States)

    Festa, G.; Pietropaolo, A.; Grazzi, F.; Sutton, L. F.; Scherillo, A.; Bognetti, L.; Bini, A.; Barzagli, E.; Schooneveld, E.; Andreani, C.

    2013-09-01

    A metallic 19th century flute was studied by means of integrated and simultaneous neutron-based techniques: neutron diffraction, neutron radiative capture analysis and neutron radiography. This experiment follows benchmark measurements devoted to assessing the effectiveness of a multitask beamline concept for neutron-based investigation on materials. The aim of this study is to show the potential application of the approach using multiple and integrated neutron-based techniques for musical instruments. Such samples, in the broad scenario of cultural heritage, represent an exciting research field. They may represent an interesting link between different disciplines such as nuclear physics, metallurgy and acoustics.

  16. Simultaneous and integrated neutron-based techniques for material analysis of a metallic ancient flute

    International Nuclear Information System (INIS)

    Festa, G; Andreani, C; Pietropaolo, A; Grazzi, F; Scherillo, A; Barzagli, E; Sutton, L F; Bognetti, L; Bini, A; Schooneveld, E

    2013-01-01

    A metallic 19th century flute was studied by means of integrated and simultaneous neutron-based techniques: neutron diffraction, neutron radiative capture analysis and neutron radiography. This experiment follows benchmark measurements devoted to assessing the effectiveness of a multitask beamline concept for neutron-based investigation on materials. The aim of this study is to show the potential application of the approach using multiple and integrated neutron-based techniques for musical instruments. Such samples, in the broad scenario of cultural heritage, represent an exciting research field. They may represent an interesting link between different disciplines such as nuclear physics, metallurgy and acoustics. (paper)

  17. Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Petre Flaviu Gostin

    2015-07-01

    Full Text Available Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to localized corrosion in halide-containing aqueous environments. Relevant features of the mechanical and corrosion behavior of Zr-based bulk metallic glasses are described, and an account of knowledge regarding corrosion-deformation interactions gathered from ex situ experimental procedures is provided. Subsequently the literature on key phenomena including hydrogen damage, stress corrosion cracking, and corrosion fatigue is reviewed. Critical factors for such phenomena will be highlighted. The review also presents an outlook for the topic.

  18. Normal metal tunnel junction-based superconducting quantum interference proximity transistor

    Energy Technology Data Exchange (ETDEWEB)

    D' Ambrosio, Sophie, E-mail: sophie.dambrosio@nano.cnr.it; Meissner, Martin; Blanc, Christophe; Ronzani, Alberto; Giazotto, Francesco, E-mail: francesco.giazotto@sns.it [NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy)

    2015-09-14

    We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current via the application of an external magnetic field. This results into a drastic suppression of power dissipation which can be as low as a few ∼10{sup −17} W. In this context, the interferometer allows an improvement of up to four orders of magnitude with respect to earlier SQUIPT designs and makes it ideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has been recently predicted to be the enabling candidate for the implementation of coherent caloritronic devices based on proximity effect.

  19. Normal metal tunnel junction-based superconducting quantum interference proximity transistor

    Science.gov (United States)

    D'Ambrosio, Sophie; Meissner, Martin; Blanc, Christophe; Ronzani, Alberto; Giazotto, Francesco

    2015-09-01

    We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current via the application of an external magnetic field. This results into a drastic suppression of power dissipation which can be as low as a few ˜10-17 W. In this context, the interferometer allows an improvement of up to four orders of magnitude with respect to earlier SQUIPT designs and makes it ideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has been recently predicted to be the enabling candidate for the implementation of coherent caloritronic devices based on proximity effect.

  20. Nanoscale luminescent lanthanide-based metal-organic frameworks: properties, synthesis, and applications

    Science.gov (United States)

    Hu, Dongqin; Song, Yonghai; Wang, Li

    2015-07-01

    Nanoscale luminescent lanthanide-based metal-organic frameworks (NLLn-MOFs) possess superior optical and physical properties such as higher luminescent lifetime, quantum yield, high stability, high surface area, high agent loading, and intrinsic biodegradability, and therefore are regarded as a novel generation of luminescent material compared with bulk lanthanide-based metal-organic frameworks (Ln-MOFs). Traditional luminescent Ln-MOFs have been well studied; however, NLLn-MOFs taking the advantages of nanomaterials have attracted extensive investigations for applications in optical imaging in living cells, light-harvesting, and sensing. In this review, we provide a survey of the latest progresses made in developing NLLn-MOFs, which contains the fundamental optical features, synthesis, and their potential applications. Finally, the future prospects and challenges of the rapidly growing field are summarized.

  1. Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels.

    Science.gov (United States)

    Subramanian, Balasubramanian; Maruthamuthu, Sundaram; Rajan, Senthilperumal Thanka

    2015-01-01

    Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.%) of approximately 1.5 μm and 3 μm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature.

  2. Inspection and Reconstruction of Metal-Roof Deformation under Wind Pressure Based on Bend Sensors.

    Science.gov (United States)

    Yang, Liman; Cui, Langfu; Li, Yunhua; An, Chao

    2017-05-06

    Metal roof sheathings are widely employed in large-span buildings because of their light weight, high strength and corrosion resistance. However, their severe working environment may lead to deformation, leakage and wind-lift, etc. Thus, predicting these damages in advance and taking maintenance measures accordingly has become important to avoid economic losses and personal injuries. Conventionally, the health monitoring of metal roofs mainly relies on manual inspection, which unavoidably compromises the working efficiency and cannot diagnose and predict possible failures in time. Thus, we proposed a novel damage monitoring scheme implemented by laying bend sensors on vital points of metal roofs to precisely monitor the deformation in real time. A fast reconstruction model based on improved Levy-type solution is established to estimate the overall deflection distribution from the measured data. A standing seam metal roof under wind pressure is modeled as an elastic thin plate with a uniform load and symmetrical boundaries. The superposition method and Levy solution are adopted to obtain the analytical model that can converge quickly through simplifying an infinite series. The truncation error of this model is further analyzed. Simulation and experiments are carried out. They show that the proposed model is in reasonable agreement with the experimental results.

  3. Spatial Pattern Analysis of Heavy Metals in Beijing Agricultural Soils Based on Spatial Autocorrelation Statistics

    Science.gov (United States)

    Huo, Xiao-Ni; Zhang, Wei-Wei; Sun, Dan-Feng; Li, Hong; Zhou, Lian-Di; Li, Bao-Guo

    2011-01-01

    This study explored the spatial pattern of heavy metals in Beijing agricultural soils using Moran’s I statistic of spatial autocorrelation. The global Moran’s I result showed that the spatial dependence of Cr, Ni, Zn, and Hg changed with different spatial weight matrixes, and they had significant and positive global spatial correlations based on distance weight. The spatial dependence of the four metals was scale-dependent on distance, but these scale effects existed within a threshold distance of 13 km, 32 km, 50 km, and 29 km, respectively for Cr, Ni, Zn, and Hg. The maximal spatial positive correlation range was 57 km, 70 km, 57 km, and 55 km for Cr, Ni, Zn, and Hg, respectively and these were not affected by sampling density. Local spatial autocorrelation analysis detected the locations of spatial clusters and spatial outliers and revealed that the pollution of these four metals occurred in significant High-high spatial clusters, Low-high, or even High-low spatial outliers. Thus, three major areas were identified and should be receiving more attention: the first was the northeast region of Beijing, where Cr, Zn, Ni, and Hg had significant increases. The second was the southeast region of Beijing where wastewater irrigation had strongly changed the content of metals, particularly of Cr and Zn, in soils. The third area was the urban fringe around city, where Hg showed a significant increase. PMID:21776217

  4. Gas Sensors Based on One Dimensional Nanostructured Metal-Oxides: A Review

    Directory of Open Access Journals (Sweden)

    A. S. M. A. Haseeb

    2012-05-01

    Full Text Available Recently one dimensional (1-D nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO2, TiO2, In2O3, WOx, AgVO3, CdO, MoO3, CuO, TeO2 and Fe2O3. Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research.

  5. Hydrogen sensors using nitride-based semiconductor diodes: the role of metal/semiconductor interfaces.

    Science.gov (United States)

    Irokawa, Yoshihiro

    2011-01-01

    In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C-V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C-V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C-V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I-V) characterization, suggesting that low-frequency C-V method would be effective in detecting very low hydrogen concentrations.

  6. Hydrogen Sensors Using Nitride-Based Semiconductor Diodes: The Role of Metal/Semiconductor Interfaces

    Directory of Open Access Journals (Sweden)

    Yoshihiro Irokawa

    2011-01-01

    Full Text Available In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C-V characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C-V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C-V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I-V characterization, suggesting that low-frequency C-V method would be effective in detecting very low hydrogen concentrations.

  7. Correlation-driven metal-insulator transition in proximity to an iron-based superconductor

    Science.gov (United States)

    Charnukha, A.; Yin, Z. P.; Song, Y.; Cao, C. D.; Dai, Pengcheng; Haule, K.; Kotliar, G.; Basov, D. N.

    2017-11-01

    We report the direct spectroscopic observation of a metal to correlated-insulator transition in the family of iron-based superconducting materials. By means of optical spectroscopy we demonstrate that the excitation spectrum of NaFe1 -xCuxAs develops a large gap with increasing copper substitution. Dynamical mean-field theory calculations show a good agreement with the experimental data and suggest that the formation of the charge gap requires an intimate interplay of strong on-site electronic correlations and spin-exchange coupling, revealing the correlated Slater-insulator nature of the antiferromagnetic ground state. Our calculations further predict the high-temperature paramagnetic state of the same compound to be a highly incoherent correlated metal. We verify this prediction experimentally by showing that the doping-induced weakening of antiferromagnetic correlations enables a thermal crossover from an insulating to an incoherent metallic state. Redistribution of the optical spectral weight in this crossover uncovers the characteristic energy of Hund's-coupling and Mott-Hubbard electronic correlations essential for the electronic localization. Our results demonstrate that NaFe1 -xCuxAs continuously transitions from the typical itinerant phases of iron pnictides to a highly incoherent metal and ultimately a correlated insulator. Such an electronic state is expected to favor high-temperature superconductivity.

  8. Molecular polypyridine-based metal complexes as catalysts for the reduction of CO2.

    Science.gov (United States)

    Elgrishi, Noémie; Chambers, Matthew B; Wang, Xia; Fontecave, Marc

    2017-02-06

    Polypyridyl transition metal complexes represent one of the more thoroughly studied classes of molecular catalysts towards CO 2 reduction to date. Initial reports in the 1980s began with an emphasis on 2nd and 3rd row late transition metals, but more recently the focus has shifted towards earlier metals and base metals. Polypyridyl platforms have proven quite versatile and amenable to studying various parameters that govern product distribution for CO 2 reduction. However, open questions remain regarding the key mechanistic steps that govern product selectivity and efficiency. Polypyridyl complexes have also been immobilized through a variety of methods to afford active catalytic materials for CO 2 reductions. While still an emerging field, materials incorporating molecular catalysts represent a promising strategy for electrochemical and photoelectrochemical devices capable of CO 2 reduction. In general, this class of compounds remains the most promising for the continued development of molecular systems for CO 2 reduction and an inspiration for the design of related non-polypyridyl catalysts.

  9. Piezoelectric sensor for sensitive determination of metal ions based on the phosphate-modified dendrimer

    Science.gov (United States)

    Wang, S. H.; Shen, C. Y.; Lin, Y. M.; Du, J. C.

    2016-08-01

    Heavy metal ions arising from human activities are retained strongly in water; therefore public water supplies must be monitored regularly to ensure the timely detection of potential problems. A phosphate-modified dendrimer film was investigated on a quartz crystal microbalance (QCM) for sensing metal ions in water at room temperature in this study. The chemical structures and sensing properties were characterized by Fourier transform infrared spectroscopy and QCM measurement, respectively. This phosphate-modified dendrimer sensor can directly detect metal ions in aqueous solutions. This novel sensor was evaluated for its capacity to sense various metal ions. The sensor exhibited a higher sensitivity level and shorter response time to copper(II) ions than other sensors. The linear detection range of the prepared QCM based on the phosphate-modified dendrimer was 0.0001 ∼ 1 μM Cu(II) ions (R2 = 0.98). The detection properties, including sensitivity, response time, selectivity, reusability, maximum adsorption capacity, and adsorption equilibrium constants, were also investigated.

  10. Retrospective analysis of heavy metal contamination in Rhode Island based on old and new herbarium specimens.

    Science.gov (United States)

    Rudin, Sofia M; Murray, David W; Whitfeld, Timothy J S

    2017-01-01

    Herbarium specimens may provide a record of past environmental conditions, including heavy metal pollution. To explore this potential, we compared concentrations of copper, lead, and zinc in historical and new collections from four sites in Rhode Island, USA. We compared historical specimens (1846 to 1916) to congener specimens collected in 2015 at three former industrial sites in Providence, Rhode Island, and one nonindustrial site on Block Island. Leaf material was prepared by UltraWAVE SRC Microwave Digestion, and heavy metal concentrations were measured by inductively coupled plasma-atomic emission spectroscopy. Heavy metal concentrations in the historical and new specimens were measurable for all elements tested, and levels of copper and zinc were comparable in the historical and 2015 collections. By contrast, the concentration of lead declined at all sites over time. Significant variability in heavy metal concentration was observed between taxa, reflecting their varied potential for elemental accumulation. It seems clear that herbarium specimens can be used to evaluate past levels of pollution and assess local environmental changes. With careful sampling effort, these specimens can be a valuable part of environmental science research. Broadening the possible applications for herbarium collections in this way increases their relevance in an era of reduced funding for collections-based research.

  11. Interfacial shear bond strength between different base metal alloys and five low fusing feldspathic ceramic systems.

    Science.gov (United States)

    Sipahi, Cumhur; Ozcan, Mutlu

    2012-01-01

    This study compared the bond strength between metal alloys and 5 ceramic systems. Ceramic systems (Vita VMK68, Ivoclar IPSd. SIGN, Ceramco II, Matchmaker and Finesse) were fired onto either Ni-Cr or Co-Cr base metal alloy. Metal-ceramic interfaces were subjected to shear loading until failure. The ceramic type significantly affected the bond strength results (palloy, the results ranged between 15.4-25.3 MPa and for Co-Cr alloy between 13.3-19.0 MPa. The highest mean bond strength value was obtained with the combination of Ni-Cr alloy-Ceramco II (25.3 MPa), the lowest bond strength was received from the combination of Co-Cr alloy-Ivoclar IPS d.SIGN ceramic (13.3 MPa). Adhesive failures between metal and ceramic were significantly more frequent with Ni-Cr alloy (31 out of 50) than with Co-Cr (20 out of 50) (p<0.05). Ceramco II presented the highest bond strength with both Ni-Cr and Co-Cr being significantly different from one another.

  12. Wear Behavior of Mechanically Alloyed Ti-Based Bulk Metallic Glass Composites Containing Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yung-Sheng Lin

    2016-11-01

    Full Text Available The present paper reports the preparation and wear behavior of mechanically alloyed Ti-based bulk metallic glass composites containing carbon nanotube (CNT particles. The differential scanning calorimeter results show that the thermal stability of the amorphous matrix is affected by the presence of CNT particles. Changes in glass transition temperature (Tg and crystallization temperature (Tx suggest that deviations in the chemical composition of the amorphous matrix occurred because of a partial dissolution of the CNT species into the amorphous phase. Although the hardness of CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composites is increased with the addition of CNT particles, the wear resistance of such composites is not directly proportional to their hardness, and does not follow the standard wear law. A worn surface under a high applied load shows that the 12 vol. % CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composite suffers severe wear compared with monolithic Ti50Cu28Ni15Sn7 bulk metallic glass.

  13. Bulk glass formation and crystallization in zirconium based bulk metallic glass forming alloys

    International Nuclear Information System (INIS)

    Savalia, R.T.; Neogy, S.; Dey, G.K.; Banerjee, S.

    2002-01-01

    The microstructures of Zr based metallic glasses produced in bulk form have been described in the as-cast condition and after crystallization. Various microscopic techniques have been used to characterize the microstructures. The microstructure in the as-cast condition was found to contain isolated crystals and crystalline aggregates embedded in the amorphous matrix. Quenched-in nuclei of crystalline phases were found to be present in fully amorphous regions. These glasses after crystallization gave rise to nanocrystalline solids. (author)

  14. Mechanical properties of permeable materials with an organized structure on the base of continuous metal fibers

    International Nuclear Information System (INIS)

    Karpinos, D.M.; Rutkovskij, A.E.; Zorin, V.A.; Ivanchuk, A.A.

    1979-01-01

    The mechanical properties were studied for permeable fibrous materials with an organized structure on the base of continuous metal fibers (from Kh18N9T steel) subjected to preliminary reprocessing volumetric net half-finished products. The effect of geometrical parameters of the net half-finished products and of their orientation in packing are shown to affect the mechanical properties within a wide range of porosities

  15. Improved image quality in abdominal CT in patients who underwent treatment for hepatocellular carcinoma with small metal implants using a raw data-based metal artifact reduction algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Sofue, Keitaro; Sugimura, Kazuro [Kobe University Graduate School of Medicine, Department of Radiology, Kobe, Hyogo (Japan); Yoshikawa, Takeshi; Ohno, Yoshiharu [Kobe University Graduate School of Medicine, Advanced Biomedical Imaging Research Center, Kobe, Hyogo (Japan); Kobe University Graduate School of Medicine, Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe, Hyogo (Japan); Negi, Noriyuki [Kobe University Hospital, Division of Radiology, Kobe, Hyogo (Japan); Inokawa, Hiroyasu; Sugihara, Naoki [Toshiba Medical Systems Corporation, Otawara, Tochigi (Japan)

    2017-07-15

    To determine the value of a raw data-based metal artifact reduction (SEMAR) algorithm for image quality improvement in abdominal CT for patients with small metal implants. Fifty-eight patients with small metal implants (3-15 mm in size) who underwent treatment for hepatocellular carcinoma were imaged with CT. CT data were reconstructed by filtered back projection with and without SEMAR algorithm in axial and coronal planes. To evaluate metal artefact reduction, mean CT number (HU and SD) and artefact index (AI) values within the liver were calculated. Two readers independently evaluated image quality of the liver and pancreas and visualization of vasculature using a 5-point visual score. HU and AI values and image quality on images with and without SEMAR were compared using the paired Student's t-test and Wilcoxon signed rank test. Interobserver agreement was evaluated using linear-weighted κ test. Mean HU and AI on images with SEMAR was significantly lower than those without SEMAR (P < 0.0001). Liver and pancreas image qualities and visualizations of vasculature were significantly improved on CT with SEMAR (P < 0.0001) with substantial or almost perfect agreement (0.62 ≤ κ ≤ 0.83). SEMAR can improve image quality in abdominal CT in patients with small metal implants by reducing metallic artefacts. (orig.)

  16. Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.

    Science.gov (United States)

    Ei Ei, Htwe; Nakama, Yuhi; Tanaka, Hiroshi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi

    2016-11-01

    The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Role of Metal Contacts in High-Performance Phototransistors Based on WSe 2 Monolayers

    KAUST Repository

    Zhang, Wenjing

    2014-08-26

    Phototransistors based on monolayer transition metal dichalcogenides (TMD) have high photosensitivity due to their direct band gap transition. However, there is a lack of understanding of the effect of metal contacts on the performance of atomically thin TMD phototransistors. Here, we fabricate phototransistors based on large-area chemical vapor deposition (CVD) tungsten diselenide (WSe2) monolayers contacted with the metals of different work function values. We found that the low Schottky-contact WSe2 phototransistors exhibit a very high photo gain (105) and specific detectivity (1014Jones), values higher than commercial Si- and InGaAs-based photodetectors; however, the response speed is longer than 5 s in ambient air. In contrast, the high Schottky-contact phototransistors display a fast response time shorter than 23 ms, but the photo gain and specific detectivity decrease by several orders of magnitude. Moreover, the fast response speed of the high Schottky-contact devices is maintained for a few months in ambient air. This study demonstrates that the contact plays an important role in TMD phototransistors, and barrier height tuning is critical for optimizing the photoresponse and photoresponsivity. © 2014 American Chemical Society.

  18. Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

    Science.gov (United States)

    Fu, Kun (Kelvin); Gong, Yunhui; Liu, Boyang; Zhu, Yizhou; Xu, Shaomao; Yao, Yonggang; Luo, Wei; Wang, Chengwei; Lacey, Steven D.; Dai, Jiaqi; Chen, Yanan; Mo, Yifei; Wachsman, Eric; Hu, Liangbing

    2017-01-01

    Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li7La3Zr2O12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10−3 to 10−4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnet solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm2 for the surface-engineered garnet/Li. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries. PMID:28435874

  19. Mechanical behavior of polymer-based vs. metallic-based bioresorbable stents

    OpenAIRE

    Ang, Hui Ying; Huang, Ying Ying; Lim, Soo Teik; Wong, Philip; Joner, Michael; Foin, Nicolas

    2017-01-01

    Bioresorbable scaffolds (BRS) were developed to overcome the drawbacks of current metallic drug-eluting stents (DES), such as late in-stent restenosis and caging of the vessel permanently. The concept of the BRS is to provide transient support to the vessel during healing before being degraded and resorbed by the body, freeing the vessel and restoring vasomotion. The mechanical properties of the BRS are influenced by the choice of the material and processing methods. Due to insufficient radia...

  20. The Gellyfish: An In-Situ Equilibrium-Based Sampler for Determining Multiple Free Metal Ion Concentrations in Marine Ecosystems

    Science.gov (United States)

    Dong, Zhao; Lewis, Christopher G.; Burgess, Robert M.; Shine, James P.

    2016-01-01

    Free metal ions are usually the most bioavailable and toxic metal species to aquatic organisms, but they are difficult to measure due to their extremely low concentrations in the marine environment. Many of the current methods for determining free metal ions are complicated, time-consuming, and can only measure one metal at a time. We developed a new version of the ‘Gellyfish’, an in-situ equilibrium-based sampler, with significantly reduced equilibration time and the capability of measuring multiple free metal ions simultaneously. By calibrating the Gellyfish to account for its uptake of cationic metal complexes and validating them in multi-metal competition experiments, we were able to determine free metal ion concentrations previously collected over ten months at five locations in Boston Harbor for Cu, Zn, Pb, Ni, and Cd. This work generated one of the largest free metal ion datasets and demonstrated the applicability of the Gellyfish as an easy-to-use and inexpensive tool for monitoring free ion concentrations of metal mixtures in marine ecosystems. PMID:25598362

  1. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...

  2. 1H NMR spectroscopic analysis detects metabolic disturbances in rat urine on acute exposure to heavy metal tungsten alloy based metals salt.

    Science.gov (United States)

    Tyagi, Ritu; Rana, Poonam; Gupta, Mamta; Bhatnagar, Deepak; Srivastava, Shatakshi; Roy, Raja; Khushu, Subash

    2014-03-25

    Heavy metal tungsten alloys (HMTAs) have been found to be safer alternatives for making military munitions. Recently, some studies demonstrating the toxic potential of HMTAs have raised concern over the safety issues, and further propose that HMTAs exposure may lead to physiological disturbances as well. To look for the systemic effect of acute toxicity of HMTA based metals salt, (1)H nuclear magnetic resonance ((1)H NMR) spectroscopic profiling of rat urine was carried out. Male Sprague Dawley rats were administered (intraperitoneal) low and high dose of mixture of HMTA based metals salt and NMR spectroscopy was carried out in urine samples collected at 8, 24, 72 and 120 h post dosing (p.d.). Serum biochemical parameters and liver histopathology were also conducted. The (1)H NMR spectra were analysed using multivariate analysis techniques to show the time- and dose-dependent biochemical variations in post HMTA based metals salt exposure. Urine metabolomic analysis showed changes associated with energy metabolism, amino acids, N-methyl nicotinamide, membrane and gut flora metabolites. Multivariate analysis showed maximum variation with best classification of control and treated groups at 24h p.d. At the end of the study, for the low dose group most of the changes at metabolite level reverted to control except for the energy metabolites; whereas, in the high dose group some of the changes still persisted. The observations were well correlated with histopathological and serum biochemical parameters. Further, metabolic pathway analysis clarified that amongst all the metabolic pathways analysed, tricarboxylic acid cycle was most affected at all the time points indicating a switchover in energy metabolism from aerobic to anaerobic. These results suggest that exposure of rats to acute doses of HMTA based metals salt disrupts physiological metabolism with moderate injury to the liver, which might indirectly result from heavy metals induced oxidative stress. Copyright

  3. Synthesis and Characterization of Sn2+- based and Bi3+- based metal oxides for photocatalytic applications

    KAUST Repository

    Noureldine, Dalal

    2016-07-01

    The main challenge of water splitting technology is to develop stable, visible responsive photocatalysts that satisfy the thermodynamic requirements to achieve water redox reactions. This study investigates development of the semiconductors containing metals with s2d10 electronic configuration such as Sn2+ or Bi3+ which shifts the valence band position negatively. Efficient water splitting can, however, be only achieved by understanding the fundamental semiconductor properties of underlying processes. This work elucidates the semiconductor properties through two approaches: the first is to synthesize the materials of various stoichiometry in various forms (powders, thin film etc.) and the second is to perform a combined experimental-theoretical studies to determine the optoelectronic properties of the synthesized materials. The study includes the synthesis and characterization of a series of Bi3+ based semiconductors (Bi2Ti2O7, Bi12TiO20, and Bi4Ti3O12) to resolve inconsistencies in their optoelectronic properties. The crystal parameters and stoichiometry were confirmed by the Rietveld refinement and XRD measurements. These compounds showed a UV responsive absorption, high dielectric constants, and low electron and hole effective masses in one crystallographic reflecting their good charge separation and carrier diffusion properties. The approach showed to be accurate in determining the optoelectronic properties due to good agreement between experimental and theoretical values. The second study investigated the synthesis of SnNb2O6 and using flux assisted method which afforded control over the surface. Increasing the flux to reactant molar ratio resulted in a 2D platelets with anisotropic growth along bc plane as confirmed by XRD and SEM. The photocatalytic activity increased while increasing the flux to reactant ratio exceeding solid state synthesis. This method minimized the oxidation of the surface and formation of grain boundaries and enabled the synthesis of

  4. Practice-based clinical evaluation of metal-ceramic and zirconia molar crowns: 3-year results.

    Science.gov (United States)

    Rinke, S; Schäfer, S; Lange, K; Gersdorff, N; Roediger, M

    2013-03-01

    This practice-based study evaluates the clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with pronounced anatomical core design and a prolonged cooling period of the veneering porcelain. Fifty-three patients were treated from 07/2008 until 07/2009 with either metal-ceramic crowns (MCC) (high-noble alloy + low-fusing porcelain) or zirconia crowns (Cercon System, DeguDent, Germany). Forty-nine patients (30 women/19 men) with 100 restorations (metal-ceramic: 48/zirconia: 52, mean observational period: 36·5 ± 6 months) participated in a clinical follow-up examination and were included in the study. Time-dependent survival (in situ criteria), success (event-free restorations) and chipping rates (defects of the veneering ceramics) were calculated according to the Kaplan-Meier method and analysed in relation to the crown fabrication technique, using a Cox regression model (P zirconia: 2) were recorded (survival rate after 3 years: metal-ceramic: 97·6%, zirconia: 95·2%). Of the metal-ceramic restorations, 90·9% remained event-free (two ceramic fractures, one endodontic treatment), whereas the success rate for the zirconia was 86·8% (two ceramic fractures, one endodontic treatment, one secondary caries). No significant differences in survival (P = 0·53), success (P = 0·49) and ceramic fracture rates (P = 0·57) were detected. The combination of a pronounced anatomical core design and a modified firing of the veneering porcelain for the fabrication of zirconia molar crowns resulted in a 3-year survival, success and chipping rate comparable to MCC. © 2012 Blackwell Publishing Ltd.

  5. A novel forward projection-based metal artifact reduction method for flat-detector computed tomography

    International Nuclear Information System (INIS)

    Prell, Daniel; Kyriakou, Yiannis; Beister, Marcel; Kalender, Willi A

    2009-01-01

    Metallic implants generate streak-like artifacts in flat-detector computed tomography (FD-CT) reconstructed volumetric images. This study presents a novel method for reducing these disturbing artifacts by inserting discarded information into the original rawdata using a three-step correction procedure and working directly with each detector element. Computation times are minimized by completely implementing the correction process on graphics processing units (GPUs). First, the original volume is corrected using a three-dimensional interpolation scheme in the rawdata domain, followed by a second reconstruction. This metal artifact-reduced volume is then segmented into three materials, i.e. air, soft-tissue and bone, using a threshold-based algorithm. Subsequently, a forward projection of the obtained tissue-class model substitutes the missing or corrupted attenuation values directly for each flat detector element that contains attenuation values corresponding to metal parts, followed by a final reconstruction. Experiments using tissue-equivalent phantoms showed a significant reduction of metal artifacts (deviations of CT values after correction compared to measurements without metallic inserts reduced typically to below 20 HU, differences in image noise to below 5 HU) caused by the implants and no significant resolution losses even in areas close to the inserts. To cover a variety of different cases, cadaver measurements and clinical images in the knee, head and spine region were used to investigate the effectiveness and applicability of our method. A comparison to a three-dimensional interpolation correction showed that the new approach outperformed interpolation schemes. Correction times are minimized, and initial and corrected images are made available at almost the same time (12.7 s for the initial reconstruction, 46.2 s for the final corrected image compared to 114.1 s and 355.1 s on central processing units (CPUs)).

  6. Improving the photocatalytic activity of s-triazine based graphitic carbon nitride through metal decoration: an ab initio investigation.

    Science.gov (United States)

    Srinivasu, K; Modak, Brindaban; Ghosh, Swapan K

    2016-09-29

    Graphitic carbon nitride based semiconductor materials are found to be potential photocatalysts for generating hydrogen through solar water splitting. Through more accurate hybrid density functional theory calculations, we attempted to tune the electronic band structure of poly s-triazine based graphitic carbon nitride by decorating it with different metal atoms and clusters for improving its visible light absorption efficiency. For deposition on the two-dimensional carbon nitride surface, a range of metals have been considered which include all the 3d transition metals and the noble metals (Ag, Au, Pt and Pd). Our study reveals that though the band gaps of all the metal decorated systems were less than that of pristine carbon nitride, in most of the cases, metal decoration leads to the formation of mid gap impurity states, which can hinder the mobility of charge carriers. However, in the case of Ag and its four atom cluster deposited systems, no mid gap states were observed. In all the metal decorated systems, the measured band edge potentials were also found to satisfy the thermodynamic criterion for overall water splitting. The calculated optical absorption spectra show a shift in the absorption band towards the visible region upon metal decoration. Our results indicate that among all the considered metal atoms silver is the preferred candidate for deposition on the carbon nitride surface for improved photocatalytic activity.

  7. Pt-based Bi-metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil

    Energy Technology Data Exchange (ETDEWEB)

    Lawal, Adeniyi [Stevens Inst. of Technology, Hoboken, NJ (United States); Manganaro, James [Anasyn LLC, Princeton, NJ (United States); Goodall, Brian [Valicor Renewables LLC, Dexter, MI (United States); Farrauto, Robert [Columbia Univ., New York, NY (United States)

    2015-03-24

    Valicor’s proprietary wet extraction process in conjunction with thermochemical pre-treatment was performed on algal biomass from two different algae strains, Nannochloropsis Salina (N.S.) and Chlorella to produce algae oils. Polar lipids such as phospholipids were hydrolyzed, and metals and metalloids, known catalyst poisons, were separated into the aqueous phase, creating an attractive “pre-refined” oil for hydrodeoxygenation (HDO) upgrading by Stevens. Oil content and oil extraction efficiency of approximately 30 and 90% respectively were achieved. At Stevens, we formulated a Pt-based bi-metallic catalyst which was demonstrated to be effective in the hydro-treating of the algae oils to produce ‘green’ diesel. The bi-metallic catalyst was wash-coated on a monolith, and in conjunction with a high throughput high pressure (pilot plant) reactor system, was used in hydrotreating algae oils from N.S. and Chlorella. Mixtures of these algae oils and refinery light atmospheric gas oil (LAGO) supplied by our petroleum refiner partner, Marathon Petroleum Corporation, were co-processed in the pilot plant reactor system using the Pt-based bi-metallic monolith catalyst. A 26 wt% N.S. algae oil/74 wt % LAGO mixture hydrotreated in the reactor system was subjected to the ASTM D975 Diesel Fuel Specification Test and it met all the important requirements, including a cetane index of 50.5. An elemental oxygen analysis performed by an independent and reputable lab reported an oxygen content of trace to none found. The successful co-processing of a mixture of algae oil and LAGO will enable integration of algae oil as a refinery feedstock which is one of the goals of DOE-BETO. We have presented experimental data that show that our precious metal-based catalysts consume less hydrogen than the conventional hydrotreating catalyst NiMo Precious metal catalysts favor the hydrodecarbonylation/hydrodecarboxylation route of HDO over the dehydration route preferred by base metal

  8. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    International Nuclear Information System (INIS)

    ME Petrichek

    2005-01-01

    Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel base alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed

  9. A numerical study of multi filament formation in metal-ion based CBRAM

    Directory of Open Access Journals (Sweden)

    Dan Berco

    2016-02-01

    Full Text Available This study investigates the underlying mechanisms of multiple conductive filaments (CF creation in metal-ion based conductive bridge RRAM (CBRAM by using the Metropolis Monte Carlo algorithm and suggests a possible explanation for this phenomenon. The simulation method is demonstrated over a Cu/HfO2 structure, starting from a random initial distribution of oxygen vacancies (OV defects in the resistive switching layer, to a formed CF and ending in a ruptured state. the results indicate that “Hot Spots” (HS, where agglomeration of OV trap like states for electron hopping based conduction induce local heating, create favorable energy conditions to attract diffused metal species originating from the top electrode. While HS may be created and annihilated by random OV generation and recombination processes, the precipitated metal forms a stem out of which a CF could evolve. The CF stem’s final growth stage is mainly driven by drift and diffusion. This process may lead to the formation of one or more CFs as a function of the forming bias voltage. This bias dependence is demonstrated over a large range, where the creation of a single, double and multiple CFs are shown. In addition, the reset process of the multi CF device is presented, and the experimentally observed, step like, gradual CBRAM reset is verified. The simulated results are in good agreement with experimental data and promote the idea that OV defect engineering may be used to improve CBRAM performance.

  10. A QM/MM refinement of an experimental DNA structure with metal-mediated base pairs.

    Science.gov (United States)

    Kumbhar, Sadhana; Johannsen, Silke; Sigel, Roland K O; Waller, Mark P; Müller, Jens

    2013-10-01

    A series of hybrid quantum mechanical/molecular mechanical (QM/MM) calculations was performed on models of a DNA duplex with artificial silver(I)-mediated imidazole base pairs. The optimized structures were compared to the original experimental NMR structure (Nat. Chem. 2 (2010) 229-234). The metal⋯metal distances are significantly shorter (~0.5Å) in the QM/MM model than in the original NMR structure. As a result, argentophilic interactions are feasible between the silver(I) ions of neighboring metal-mediated base pairs. Using the computationally determined metal⋯metal distances, a re-refined NMR solution structure of the DNA duplex was obtained. In this new NMR structure, all experimental constraints remain fulfilled. The new NMR structure shows less deviation from the regular B-type conformation than the original one. This investigation shows that the application of QM/MM models to generate additional constraints to be used during NMR structural refinements represents an elegant approach to obtaining high-resolution NMR structures. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. A unified dislocation density-dependent physical-based constitutive model for cold metal forming

    Science.gov (United States)

    Schacht, K.; Motaman, A. H.; Prahl, U.; Bleck, W.

    2017-10-01

    Dislocation-density-dependent physical-based constitutive models of metal plasticity while are computationally efficient and history-dependent, can accurately account for varying process parameters such as strain, strain rate and temperature; different loading modes such as continuous deformation, creep and relaxation; microscopic metallurgical processes; and varying chemical composition within an alloy family. Since these models are founded on essential phenomena dominating the deformation, they have a larger range of usability and validity. Also, they are suitable for manufacturing chain simulations since they can efficiently compute the cumulative effect of the various manufacturing processes by following the material state through the entire manufacturing chain and also interpass periods and give a realistic prediction of the material behavior and final product properties. In the physical-based constitutive model of cold metal plasticity introduced in this study, physical processes influencing cold and warm plastic deformation in polycrystalline metals are described using physical/metallurgical internal variables such as dislocation density and effective grain size. The evolution of these internal variables are calculated using adequate equations that describe the physical processes dominating the material behavior during cold plastic deformation. For validation, the model is numerically implemented in general implicit isotropic elasto-viscoplasticity algorithm as a user-defined material subroutine (UMAT) in ABAQUS/Standard and used for finite element simulation of upsetting tests and a complete cold forging cycle of case hardenable MnCr steel family.

  12. Gas Sensors Based on Locally Heated Multiwall Carbon Nanotubes Decorated with Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    R. Savu

    2015-01-01

    Full Text Available We report the design and fabrication of microreactors and sensors based on metal nanoparticle-decorated carbon nanotubes. Titanium adhesion layers and gold films were sputtered onto Si/SiO2 substrates for obtaining the electrical contacts. The gold layers were electrochemically thickened until 1 μm and the electrodes were patterned using photolithography and wet chemical etching. Before the dielectrophoretic deposition of the nanotubes, a gap 1 μm wide and 5 μm deep was milled in the middle of the metallic line by focused ion beam, allowing the fabrication of sensors based on suspended nanotubes bridging the electrodes. Subsequently, the sputtering technique was used for decorating the nanotubes with metallic nanoparticles. In order to test the as-obtained sensors, microreactors (100 μL volume were machined from a single Kovar piece, being equipped with electrical connections and 1/4′′ Swagelok-compatible gas inlet and outlets for controlling the atmosphere in the testing chamber. The sensors, electrically connected to the contact pins by wire-bonding, were tested in the 10−5 to 10−2 W working power interval using oxygen as target gas. The small chamber volume allowed the measurement of fast characteristic times (response/recovery, with the sensors showing good sensitivity.

  13. Non-Noble Metal-based Carbon Composites in Hydrogen Evolution Reaction: Fundamentals to Applications.

    Science.gov (United States)

    Wang, Jing; Xu, Fan; Jin, Haiyan; Chen, Yiqing; Wang, Yong

    2017-04-01

    Hydrogen has been hailed as a clean and sustainable alternative to finite fossil fuels in many energy systems. Water splitting is an important method for hydrogen production in high purity and large quantities. To accelerate the hydrogen evolution reaction (HER) rate, it is highly necessary to develop high efficiency catalysts and to select a proper electrolyte. Herein, the performances of non-noble metal-based carbon composites under various pH values (acid, alkaline and neutral media) for HER in terms of catalyst synthesis, structure and molecular design are systematically discussed. A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provide guidance for future HER mechanism studies on non-noble metal-based carbon composites. Furthermore, this Review gives a fresh impetus to rational design of high-performance noble-metal-free composites catalysts and guide researchers to employ the established electrocatalysts in proper water electrolysis technologies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Design for a Crane Metallic Structure Based on Imperialist Competitive Algorithm and Inverse Reliability Strategy

    Science.gov (United States)

    Fan, Xiao-Ning; Zhi, Bo

    2017-07-01

    Uncertainties in parameters such as materials, loading, and geometry are inevitable in designing metallic structures for cranes. When considering these uncertainty factors, reliability-based design optimization (RBDO) offers a more reasonable design approach. However, existing RBDO methods for crane metallic structures are prone to low convergence speed and high computational cost. A unilevel RBDO method, combining a discrete imperialist competitive algorithm with an inverse reliability strategy based on the performance measure approach, is developed. Application of the imperialist competitive algorithm at the optimization level significantly improves the convergence speed of this RBDO method. At the reliability analysis level, the inverse reliability strategy is used to determine the feasibility of each probabilistic constraint at each design point by calculating its α-percentile performance, thereby avoiding convergence failure, calculation error, and disproportionate computational effort encountered using conventional moment and simulation methods. Application of the RBDO method to an actual crane structure shows that the developed RBDO realizes a design with the best tradeoff between economy and safety together with about one-third of the convergence speed and the computational cost of the existing method. This paper provides a scientific and effective design approach for the design of metallic structures of cranes.

  15. Metal-Free Carbon-Based Nanomaterial Coatings Protect Silicon Photoanodes in Solar Water-Splitting.

    Science.gov (United States)

    Yoon, KunHo; Lee, Jae-Hyeok; Kang, Joohoon; Kang, Junmo; Moody, Michael J; Hersam, Mark C; Lauhon, Lincoln J

    2016-12-14

    The decreasing cost of silicon-based photovoltaics has enabled significant increases in solar electricity generation worldwide. Silicon photoanodes could also play an important role in the cost-effective generation of solar fuels, but the most successful methods of photoelectrode passivation and performance enhancement rely on a combination of precious metals and sophisticated processing methods that offset the economic arguments for silicon. Here we show that metal-free carbon-based nanomaterial coatings deposited from solution can protect silicon photoanodes carrying out the oxygen evolution reaction in a range of working environments. Purified semiconducting carbon nanotubes (CNTs) act as a hole extraction layer, and a graphene (Gr) capping layer both protects the CNT film and acts as a hole exchange layer with the electrolyte. The performance of semiconducting CNTs is found to be superior to that of metallic or unsorted CNTs in this context. Furthermore, the insertion of graphene oxide (GO) between the n-Si and CNTs reduces the overpotential relative to photoanodes with CNTs deposited on hydrogen-passivated silicon. The composite photoanode structure of n-Si/GO/CNT/Gr shows promising performance for oxygen evolution and excellent potential for improvement by optimizing the catalytic properties and stability of the graphene protective layer.

  16. Synthesis, structure, DNA/BSA binding and antibacterial studies of NNO tridentate Schiff base metal complexes

    Science.gov (United States)

    Sakthi, Marimuthu; Ramu, Andy

    2017-12-01

    A new salicylaldehyde derived 2,4-diiodo-6-((2-phenylaminoethylimino)methyl)phenol Schiff base(L) and its transition metal complexes of the type MLCl where, M = Cu(II), Ni(II), Co(II), Mn(II) and Zn(II) have been synthesized. The coordination mode of Schiff base holding NNO donor atoms with metal ions was well investigated by elemental analysis, ESI-mass as well as IR, UV-vis, CV and NMR spectral studies. The binding efficiency and mode of these complexes with biological macromolecules viz., herring sperm DNA (HS- DNA) and bovine serum albumin (BSA) have been explored through various spectroscopic techniques. The characteristic changes in absorption, emission and, circular dichroism spectra of the complexes with DNA indicate the noticeable interaction between them. From the all spectral information complexes could interact with DNA via non-intercalation mode of binding. The hyperchromisim in absorption band and hypochromisim in emission intensity of BSA with different complex concentrations shown significant information, and the binding affinity value has been predicted from Stern-Volmer plots. Further, all the complexes could cleave the circular plasmid pUC19 DNA efficiently by using an activator H2O2. The ligand and all metal(II) complexes showed good antibacterial activities. The molecular docking studies of the complexes with DNA were performed in order to make a comparison and conclusion with spectral technic results.

  17. Study of surface modifications for improved selected metal (II-VI) semiconductor based devices

    Science.gov (United States)

    Blomfield, Christopher James

    Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe.Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state.Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi

  18. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles.

    KAUST Repository

    Choudhury, Snehashis

    2015-12-04

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

  19. Hard metals performance evaluation based on testing the transitions in their wear behaviour

    International Nuclear Information System (INIS)

    Scieszka, S.F.; Filipowicz, K.

    2000-01-01

    Abrasive wear and brittle fracture lead to massive losses of function in drilling and mining equipment involving high replacement costs and extended downtime. In industrial processes involving direct impact and rubbing contact the main question remains unanswered - namely what is the optimal balance between wear resistance and fracture toughness of rock-bit hard metals. The apparatus and method presented in this paper might be able to fill this gap. During the course of this investigation the abrasive wear resistance and the fracture toughness of fifteen selected hard metals were evaluated. The apparatus used simulated the tribo-condition between drilling (mining) tools and the rock. The equation that enables calculation of the fracture toughness factor K WR , based on results from the carefully controlled repeated abrasion tests, is proposed (author)

  20. Ionic-Liquid-Based Acidic Aqueous Biphasic Systems for Simultaneous Leaching and Extraction of Metallic Ions.

    Science.gov (United States)

    Gras, Matthieu; Papaiconomou, Nicolas; Schaeffer, Nicolas; Chainet, Eric; Tedjar, Farouk; Coutinho, Joao A P; Billard, Isabelle

    2018-02-05

    The first instance of an acidic aqueous biphasic system (AcABS) based on tributyltetradecyl phosphonium chloride ([P 44414 ][Cl]) and an acid is here reported. This AcABS exhibits pronounced thermomorphic behavior and is shown to be applicable to the extraction of metal ions from concentrated acidic solutions. Metal ions such as cobalt(II), iron(III), platinum(IV) and nickel(II) are found to partition preferentially to one of the phases of the acidic aqueous biphasic system and it is here shown that it successfully allows the difficult separation of Co II from Ni II , here studied at 24 and 50 °C. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Design of an ultrabroadband visible metamaterial absorber based on three-dimensional metallic nanostructures

    Science.gov (United States)

    Luo, Hao; Cheng, Yong Zhi

    2017-09-01

    We present the design and numerical simulations of an ultrabroadband visible metamaterial absorber (MMA) with polarization-insensitive and wide-angle based on three-dimensional (3D) metallic nanostructure. Distinct from previous designs, the proposed visible MMA only consisted of structured 3D metallic film constructed with an assembly of four vertical split-rings (FVSR) structure. For the optimized design of our MMA, the absorbance of over 90% with a relative bandwidth of 94.8% can be obtained. Further simulation results indicate that our design is polarization-insensitive and also operated well in a wide range of incident angles for both TE and TM modes. In addition, the designed visible MMA design can tolerate some geometric parameters errors in fabrication. Thus, the proposed visible MMA can be potential application in the photodetectors, thermal imaging, photoelectrochemical, and solar energy harvesting devices.

  2. Alternative Processes for Manufacturing of Metal Oxide-based Potentiometric Chemosensors

    Directory of Open Access Journals (Sweden)

    Winfried VONAU

    2015-10-01

    Full Text Available New possibilities for the preparation of partially selective redox electrodes based on passivated metals of the subgroups IV to VI of the periodic system are presented by the example of vanadium. The gas phase oxidation at controlled oxygen partial pressures (CPO and the pulsed laser deposition (PLD as an high-vacuum method are utilised as alternative methods beside the well- established chemical and electrochemical passivation which usually lead to the highest possible oxidation state of the passivated metal. These newly available methods enable in principle the tailoring of oxidation states in the sensitive layer and therefore the optimisation of the electrochemical sensitivity and selectivity of sensors equipped with it. The use of vanadium as basic electrode material is crucial because it shows in several matrices a remarkable corrosion susceptibility. This problem can be solved by the introduction of stable alloys with high vanadium contents. These materials can be efficiently produced by pulsed laser deposition (PLD.

  3. A constitutive model of nanocrystalline metals based on competing grain boundary and grain interior deformation mechanisms

    KAUST Repository

    Gurses, Ercan

    2011-12-01

    In this work, a viscoplastic constitutive model for nanocrystalline metals is presented. The model is based on competing grain boundary and grain interior deformation mechanisms. In particular, inelastic deformations caused by grain boundary diffusion, grain boundary sliding and dislocation activities are considered. Effects of pressure on the grain boundary diffusion and sliding mechanisms are taken into account. Furthermore, the influence of grain size distribution on macroscopic response is studied. The model is shown to capture the fundamental mechanical characteristics of nanocrystalline metals. These include grain size dependence of the strength, i.e., both the traditional and the inverse Hall-Petch effects, the tension-compression asymmetry and the enhanced rate sensitivity. © 2011 Elsevier B.V. All rights reserved.

  4. Modeling Adsorption Based Filters (Bio-remediation of Heavy Metal Contaminated Water)

    Science.gov (United States)

    McCarthy, Chris

    I will discuss kinetic models of adsorption, as well as models of filters based on those mechanisms. These mathematical models have been developed in support of our interdisciplinary lab group, which is centered at BMCC/CUNY (City University of New York). Our group conducts research into bio-remediation of heavy metal contaminated water via filtration. The filters are constructed out of biomass, such as spent tea leaves. The spent tea leaves are available in large quantities as a result of the industrial production of tea beverages. The heavy metals bond with the surfaces of the tea leaves (adsorption). The models involve differential equations, stochastic methods, and recursive functions. I will compare the models' predictions to data obtained from computer simulations and experimentally by our lab group. Funding: CUNY Collaborative Incentive Research Grant (Round 12); CUNY Research Scholars Program.

  5. A Review of Model-Based Design Tools for Metal-Air Batteries

    Directory of Open Access Journals (Sweden)

    Simon Clark

    2018-01-01

    Full Text Available The advent of large-scale renewable energy generation and electric mobility is driving a growing need for new electrochemical energy storage systems. Metal-air batteries, particularly zinc-air, are a promising technology that could help address this need. While experimental research is essential, it can also be expensive and time consuming. The utilization of well-developed theory-based models can improve researchers’ understanding of complex electrochemical systems, guide development, and more efficiently utilize experimental resources. In this paper, we review the current state of metal-air batteries and the modeling methods that can be implemented to advance their development. Microscopic and macroscopic modeling methods are discussed with a focus on continuum modeling derived from non-equilibrium thermodynamics. An applied example of zinc-air battery engineering is presented.

  6. A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration.

    Science.gov (United States)

    Bai, Min; Huang, Hui; Hao, Jian; Zhang, Ji; Wu, Haibo; Qu, Bo

    2015-05-28

    Trace analysis of liquid samples has wide applications in life science and environmental monitor. In this paper, a compact and low-cost photometer based on metal-waveguide-capillary (MWC) was developed for ultra-sensitive absorbance detection. The optical-path can be greatly enhanced and much longer than the physical length of MWC, because the light scattered by the rippled and smooth metal sidewall can be confined inside the capillary regardless of the incident-angle. For the photometer with a 7 cm long MWC, the detection limit is improved ~3000 fold compared with that of commercial spectrophotometer with 1 cm-cuvette, owing to the novel nonlinear optical-path enhancement as well as fast sample switching, and detecting glucose of a concentration as low as 5.12 nM was realized with conventional chromogenic reagent.

  7. Preparation of Al-based metal matrix composites reinforced by Cu coated SiC particles

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hailong; Zhang Rui; Xu Hongliang; Lu Hongxia; Guan Shaokang [Coll. of Materials Engineering, Zhengzhou Univ., HEN (China)

    2005-07-01

    In order to improve the interfacial behavior between SiC and Al, a surface layer of Cu was coated on SiC particles. The influence of pH value on the coating process was analyzed. A powder metallurgy method was used to prepare the Al-based metal matrix composites (MMCs). SEM, XRD techniques were used to characterize the sintered compacts. It was found that the optimized pH value during the coating process was 1{proportional_to}2. The specimen showed the maximum density when sintered at 750 C. Inter-metallic compound of Al{sub 3.21}Si{sub 0.47} was detected which contributed to the enhancement at the interface between SiC and Al. The hardness of the composites is improved to 90 MPa. (orig.)

  8. A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations

    Directory of Open Access Journals (Sweden)

    Umit Cakir

    2007-09-01

    Full Text Available The constants of the extraction equilibrium and the distribution fordichloromethane as an organic solvent having low dielectric constant of metal cations withchiral Schiff bases, benzaldehydene-(S-2-amino-3-phenylpropanol (I, o- benzaldehydene-(S-2-hydroxybenzaldehydene-(S-2-amino-3-phenyl-propanol (II,amino-3-methylbutanol (III with anionic dyes [4-(2-pyridylazo-resorcinol mono sodiummonohydrate (NaPar, sodium picrat (NaPic and potassium picrat (KPic] and some heavymetal chlorides were determined at 25 oC. All the ligands have given strongestcomplexation for NaPar. In contrast, similar behaviour for both alkali metal picrates is notapparent in the complexation of corresponding ligands.

  9. Ligand and Metal Based Multielectron Redox Chemistry of Cobalt Supported by Tetradentate Schiff Bases.

    Science.gov (United States)

    Andrez, Julie; Guidal, Valentin; Scopelliti, Rosario; Pécaut, Jacques; Gambarelli, Serge; Mazzanti, Marinella

    2017-06-28

    We have investigated the influence of bound cations on the reduction of cobalt complexes of redox active ligands and explored the reactivity of reduced species with CO 2 . The one electron reduction of [Co II ( R salophen)] with alkali metals (M = Li, Na, K) leads to either ligand-centered or metal-centered reduction depending on the alkali ion. It affords either the [Co I ( R salophen)K] complexes or the [Co II 2 (bis-salophen)M 2 ] (M = Li, Na) dimers that are present in solution in equilibrium with the respective [Co I (salophen)M] complexes. The two electron reduction of [Co II ( OMe salophen)] results in both ligand centered and metal centered reduction affording the Co(I)-Co(II)-Co(I) [Co 3 (tris- OMe salophen)Na 6 (THF) 6 ], 6 complex supported by a bridging deca-anionic tris- OMe salophen 10- ligand where three OMe salophen units are connected by two C-C bonds. Removal of the Na ion from 6 leads to a redistribution of the electrons affording the complex [(Co( OMe salophen)) 2 Na][Na(cryptand)] 3 , 7. The EPR spectrum of 7 suggests the presence of a Co(I) bound to a radical anionic ligand. Dissolution of 7 in pyridine leads to the isolation of [Co I 2 (bis- OMe salophen)Na 2 Py 4 ][Na(cryptand)] 2 , 8. Complex 6 reacts with ambient CO 2 leading to multiple CO 2 reduction products. The product of CO 2 addition to the OMe salophen ligand, [Co( OMe salophen-CO 2 )Na] 2 [Na(cryptand)] 2 , 9, was isolated but CO 3 2- formation in 53% yield was also detected. Thus, the electrons stored in the reversible C-C bonds may be used for the transformation of carbon dioxide.

  10. Investigation on Wire Electrochemical Micro Machining of Ni-based Metallic Glass

    International Nuclear Information System (INIS)

    Meng, Lingchao; Zeng, Yongbin; Zhu, Di

    2017-01-01

    Highlights: • WECMM with nanosecond pulses is proposed firstly for fabricating micro complex components based on metallic glasses. • Applicable electrolyte for WECMM of the Ni-based MG is discussed. • Significantly uniform machined surface is achieved in H 2 SO 4 solution. • High machining efficiency and stability are obtained experimentally by modifying pulse waveforms and electrolyte compositions. • Complex microstructures of Ni-based MG are fabricated by WECMM with optimized parameters. - Abstract: Metallic glasses (MGs) have been recognized as promising materials for realizing high-performance micro devices in micro electromechanical systems (MEMS) due to their excellent functional and structural characteristics. However, the applications of MGs are currently limited because of the difficulty of shaping them on the microscale. Wire electrochemical micro machining (WECMM) is increasingly recognized as a flexible and effective method to fabricate complex-shaped micro metal components with many advantages relative to the thermomechanical processing, which appears to be well suitable for micro shaping of MGs. We consider the example of a Ni-based MG, Ni 72 Cr 19 Si 7 B 2 , which has a typical passivation characteristic in 0.1 M H 2 SO 4 solution. The transpassive process can be used for localized material removal when combined with nanosecond pulsed WECMM technique. In present work, the applicable electrolyte for WECMM of the Ni-based MG was discussed firstly. Then the voltage pulse waveform and electrolyte composition were modified to improve machining efficiency and stability. Several complex microstructures such as micro curved cantilever beam, micro gear, and micro square helix were machined with different optimized parameters.

  11. Effects of Metallic Nanoparticles on Interfacial Intermetallic Compounds in Tin-Based Solders for Microelectronic Packaging

    Science.gov (United States)

    Haseeb, A. S. M. A.; Arafat, M. M.; Tay, S. L.; Leong, Y. M.

    2017-10-01

    Tin (Sn)-based solders have established themselves as the main alternative to the traditional lead (Pb)-based solders in many applications. However, the reliability of the Sn-based solders continues to be a concern. In order to make Sn-based solders microstructurally more stable and hence more reliable, researchers are showing great interest in investigating the effects of the incorporation of different nanoparticles into them. This paper gives an overview of the influence of metallic nanoparticles on the characteristics of interfacial intermetallic compounds (IMCs) in Sn-based solder joints on copper substrates during reflow and thermal aging. Nanocomposite solders were prepared by mechanically blending nanoparticles of nickel (Ni), cobalt (Co), zinc (Zn), molybdenum (Mo), manganese (Mn) and titanium (Ti) with Sn-3.8Ag-0.7Cu and Sn-3.5Ag solder pastes. The composite solders were then reflowed and their wetting characteristics and interfacial microstructural evolution were investigated. Through the paste mixing route, Ni, Co, Zn and Mo nanoparticles alter the morphology and thickness of the IMCs in beneficial ways for the performance of solder joints. The thickness of Cu3Sn IMC is decreased with the addition of Ni, Co and Zn nanoparticles. The thickness of total IMC layer is decreased with the addition of Zn and Mo nanoparticles in the solder. The metallic nanoparticles can be divided into two groups. Ni, Co, and Zn nanoparticles undergo reactive dissolution during solder reflow, causing in situ alloying and therefore offering an alternative route of alloy additions to solders. Mo nanoparticles remain intact during reflow and impart their influence as discrete particles. Mechanisms of interactions between different types of metallic nanoparticles and solder are discussed.

  12. A generalized physiologically-based toxicokinetic modeling system for chemical mixtures containing metals

    Directory of Open Access Journals (Sweden)

    Isukapalli Sastry S

    2010-06-01

    Full Text Available Abstract Background Humans are routinely and concurrently exposed to multiple toxic chemicals, including various metals and organics, often at levels that can cause adverse and potentially synergistic effects. However, toxicokinetic modeling studies of exposures to these chemicals are typically performed on a single chemical basis. Furthermore, the attributes of available models for individual chemicals are commonly estimated specifically for the compound studied. As a result, the available models usually have parameters and even structures that are not consistent or compatible across the range of chemicals of concern. This fact precludes the systematic consideration of synergistic effects, and may also lead to inconsistencies in calculations of co-occurring exposures and corresponding risks. There is a need, therefore, for a consistent modeling framework that would allow the systematic study of cumulative risks from complex mixtures of contaminants. Methods A Generalized Toxicokinetic Modeling system for Mixtures (GTMM was developed and evaluated with case studies. The GTMM is physiologically-based and uses a consistent, chemical-independent physiological description for integrating widely varying toxicokinetic models. It is modular and can be directly "mapped" to individual toxicokinetic models, while maintaining physiological consistency across different chemicals. Interaction effects of complex mixtures can be directly incorporated into the GTMM. Conclusions The application of GTMM to different individual metals and metal compounds showed that it explains available observational data as well as replicates the results from models that have been optimized for individual chemicals. The GTMM also made it feasible to model toxicokinetics of complex, interacting mixtures of multiple metals and nonmetals in humans, based on available literature information. The GTMM provides a central component in the development of a "source

  13. A new method for the characterisation and quantitative speciation of base metal smelter stack particulates.

    Science.gov (United States)

    Skeaff, James M; Thibault, Yves; Hardy, David J

    2011-06-01

    Base metal smelters may be a source of particulates containing metals of environmental concern released to the atmosphere. Knowledge of the quantitative chemical speciation of particulate releases from base metal smelters will be of value in smelter emission fingerprinting, site-specific risk assessments, predictions of the behaviour of smelter stack particulates released to the environment and in resolving liability issues related to current and historic releases. Accordingly, we have developed an innovative approach comprising bulk chemical analysis, a leaching procedure, X-ray diffraction analysis and scanning electron microscopy/electron probe microanalysis characterisation in a step-wise apportioning procedure to derive the quantitative speciation of particulate samples from the stacks of three copper smelters designated as A, B and C. For the A smelter stack particulates, the major calculated percentages were 29 CuSO(4), 20 ZnSO(4).H(2)O, 13 (Cu(0.94)Zn(0.06))(2)(AsO(4))(OH), 11 PbSO(4) and four As(2)O(3). For the B smelter stack particulates, the primary calculated percentages were 20 ZnSO(4).H(2)O, 20 PbSO(4), 12 CuSO(4) and nine As(2)O(3). Finally, we calculated that the C smelter stack particulates mostly comprised 34 ZnSO(4).H(2)O, 19 (Cu(0.84)Zn(0.16))(AsO(3)OH), 11 PbSO(4), 10 As(2)O(3) and nine Zn(3)(AsO(4))(2). Between 56% and 67% by weight of the smelter stack particulates, including the As, was soluble in water. For these and other operations, the data and approach may be useful in estimating metals partitioning among water, soil and sediment, as well as predictions of the effects of the stack particulates released to the environment.

  14. Image-based metal artifact reduction in x-ray computed tomography utilizing local anatomical similarity

    Science.gov (United States)

    Dong, Xue; Yang, Xiaofeng; Rosenfield, Jonathan; Elder, Eric; Dhabaan, Anees

    2017-03-01

    X-ray computed tomography (CT) is widely used in radiation therapy treatment planning in recent years. However, metal implants such as dental fillings and hip prostheses can cause severe bright and dark streaking artifacts in reconstructed CT images. These artifacts decrease image contrast and degrade HU accuracy, leading to inaccuracies in target delineation and dose calculation. In this work, a metal artifact reduction method is proposed based on the intrinsic anatomical similarity between neighboring CT slices. Neighboring CT slices from the same patient exhibit similar anatomical features. Exploiting this anatomical similarity, a gamma map is calculated as a weighted summation of relative HU error and distance error for each pixel in an artifact-corrupted CT image relative to a neighboring, artifactfree image. The minimum value in the gamma map for each pixel is used to identify an appropriate pixel from the artifact-free CT slice to replace the corresponding artifact-corrupted pixel. With the proposed method, the mean CT HU error was reduced from 360 HU and 460 HU to 24 HU and 34 HU on head and pelvis CT images, respectively. Dose calculation accuracy also improved, as the dose difference was reduced from greater than 20% to less than 4%. Using 3%/3mm criteria, the gamma analysis failure rate was reduced from 23.25% to 0.02%. An image-based metal artifact reduction method is proposed that replaces corrupted image pixels with pixels from neighboring CT slices free of metal artifacts. This method is shown to be capable of suppressing streaking artifacts, thereby improving HU and dose calculation accuracy.

  15. Metal oxide-based nanoparticles: revealing their potential to enhance oil recovery in different wettability systems

    Science.gov (United States)

    Hendraningrat, Luky; Torsæter, Ole

    2015-02-01

    This paper presents systematic studies of hydrophilic metal oxide nanoparticles (NPs) dispersed in brine intended to reveal their potential to enhance oil recovery (EOR) in various rock wettability systems. The stability in suspension (nanofluid) of the NPs has been identified as a key factor related to their use as an EOR agent. Experimental techniques have been developed for nanofluid stability using three coupled methods: direct visual observation, surface conductivity and particle size measurements. The use of a dispersant has been investigated and has been shown to successfully improve metal oxide nanofluid stability as a function of its concentration. The dispersant alters the nanofluid properties, i.e. surface conductivity, pH and particle size distribution. A two-phase coreflood experiment was conducted by injecting the stable nanofluids as a tertiary process (nano-EOR) through core plugs with various wettabilities ranging from water-wet to oil-wet. The combination of metal oxide nanofluid and dispersant improved the oil recovery to a greater extent than either silica-based nanofluid or dispersant alone in all wettability systems. The contact angle, interfacial tension (IFT) and effluent were also measured. It was observed that metal oxide-based nanofluids altered the quartz plates to become more water-wet, and the results are consistent with those of the coreflood experiment. The particle adsorption during the transport process was identified from effluent analysis. The presence of NPs and dispersant reduced the IFT, but its reduction is sufficient to yield significant additional oil recovery. Hence, wettability alteration plays a dominant role in the oil displacement mechanism using nano-EOR.

  16. Differentiation of nonferrous metal particles in lubrication oil using an electrical conductivity measurement-based inductive sensor

    Science.gov (United States)

    Wu, Yu; Zhang, Hongpeng; Wang, Man; Chen, Haiquan

    2018-02-01

    A method that measures the electrical conductivity of metal based on monitoring the inductance changes of coils via an inductive sensor is introduced in this work to differentiate metal particles in lubrication oil. Theoretical analysis coupled with experimentation is employed to differentiate varieties of nonferrous metal particles, including copper and aluminum particles, ranging from 860 μm to 880 μm in diameter. The results show that the inductive sensor is capable of the identification and differentiation of nonferrous metal particles in lubrication oil based on the electrical conductivity measurement. The concept demonstrated in this paper can be extended to inductive sensors in metal particle detection and other scientific and industrial applications.

  17. A versatile MOF-based trap for heavy metal ion capture and dispersion

    OpenAIRE

    Peng, Yaguang; Huang, Hongliang; Zhang, Yuxi; Kang, Chufan; Chen, Shuangming; Song, Li; Liu, Dahuan; Zhong, Chongli

    2018-01-01

    Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, ...

  18. Ross filter pairs for metal artefact reduction in x-ray tomography: a case study based on imaging and segmentation of metallic implants

    Science.gov (United States)

    Arhatari, Benedicta D.; Abbey, Brian

    2018-01-01

    Ross filter pairs have recently been demonstrated as a highly effective means of producing quasi-monoenergetic beams from polychromatic X-ray sources. They have found applications in both X-ray spectroscopy and for elemental separation in X-ray computed tomography (XCT). Here we explore whether they could be applied to the problem of metal artefact reduction (MAR) for applications in medical imaging. Metal artefacts are a common problem in X-ray imaging of metal implants embedded in bone and soft tissue. A number of data post-processing approaches to MAR have been proposed in the literature, however these can be time-consuming and sometimes have limited efficacy. Here we describe and demonstrate an alternative approach based on beam conditioning using Ross filter pairs. This approach obviates the need for any complex post-processing of the data and enables MAR and segmentation from the surrounding tissue by exploiting the absorption edge contrast of the implant.

  19. Role of perfluoropolyether-based electrolytes in lithium metal batteries: Implication for suppressed Al current collector corrosion and the stability of Li metal/electrolytes interfaces

    Science.gov (United States)

    Cong, Lina; Liu, Jia; Armand, Michel; Mauger, Alain; Julien, Christian M.; Xie, Haiming; Sun, Liqun

    2018-03-01

    The development of safe and high performance lithium metal batteries represents a major technological challenge for this new century. Historically, intrinsic instabilities of conventional liquid organic electrolytes induced battery failures and safety issues that hinder the practical utilization of advanced rechargeable lithium metal batteries. Herein, we report a multifunctional perfluoropolyether-based liquid polymer electrolyte (PFPE-MC/LiTFSI), presenting a unique "anion-solvent" interaction. This interaction optimizes the interfacial chemistry of lithium metal batteries, which effectively inhibits the corrosion of aluminum current collectors, suppresses lithium dendrite growth, and also facilitates the formation of a thin and stable SEI layer on Li anode. Even at a high current density of 0.7 mA cm-2, the lithium dendrites do not form after 1360 h of continuous operation. The LiFePO4|PFPE-MC/LiTFSI|Li cell delivers a stable cycling performance with over 99.9% columbic efficiency either at ambient temperature or high temperature, which is significantly superior to those using traditional carbonate electrolytes. In addition, PFPE-MC/LiTFSI electrolyte also possesses eye-catching properties, such as being non-flammable, non-volatile, non-hygroscopic, and existing in the liquid state between -90 °C and 200 °C, which further ensures the high safety of the lithium metal batteries, making this electrolyte promising for the development of high energy lithium metal batteries.

  20. [Analysis of heavy-metal-mediated disease and development of a novel remediation system based on fieldwork and experimental research].

    Science.gov (United States)

    Yajima, Ichiro; Zou, Cunchao; Li, Xiang; Nakano, Chizuru; Omata, Yasuhiro; Kumasaka, Mayuko Y

    2015-01-01

    Heavy-metal pollution occurs in various environments, including water, air and soil, and has serious effects on human health. Since heavy-metal pollution in drinking water causes various diseases including skin cancer, it has become a global problem worldwide. However, there is limited information on the mechanism of development of heavy-metal-mediated disease. We performed both fieldwork and experimental studies to elucidate the levels of heavy-metal pollution and mechanisms of development of heavy-metal-related disease and to develop a novel remediation system. Our fieldwork in Bangladesh, Vietnam and Malaysia demonstrated that drinking well water in these countries was polluted with high concentrations of several heavy metals including arsenic, barium, iron and manganese. Our experimental studies based on the data from our fieldwork demonstrated that these heavy metals caused skin cancer and hearing loss. Further experimental studies resulted in the development of a novel remediation system with which toxic heavy metals were absorbed from polluted drinking water. Implementation of both fieldwork and experimental studies is important for prediction, prevention and therapy of heavy-metal-mediated diseases.

  1. Zirconium-Based metal organic framework (Zr-MOF) material with high hydrostability for hydrogen storage applications

    CSIR Research Space (South Africa)

    Ren, Jianwei

    2013-09-01

    Full Text Available Material-based solutions, such as metal organic frameworks (MOFs), continue to attract increasing attention as viable options for hydrogen storage applications. MOFs are widely regarded as promising materials for hydrogen storage due to their high...

  2. High-energy in-beam neutron measurements of metal-based shielding for accelerator-driven spallation neutron sources

    Science.gov (United States)

    DiJulio, D. D.; Cooper-Jensen, C. P.; Björgvinsdóttir, H.; Kokai, Z.; Bentley, P. M.

    2016-05-01

    Metal-based shielding plays an important role in the attenuation of harmful and unwanted radiation at an accelerator-driven spallation neutron source. At the European Spallation Source, currently under construction in Lund, Sweden, metal-based materials are planned to be used extensively as neutron guide substrates in addition to other shielding structures around neutron guides. The usage of metal-based materials in the vicinity of neutron guides however requires careful consideration in order to minimize potential background effects in a neutron instrument at the facility. Therefore, we have carried out a combined study involving high-energy neutron measurements and Monte Carlo simulations of metal-based shielding, both to validate the simulation methodology and also to investigate the benefits and drawbacks of different metal-based solutions. The measurements were carried out at The Svedberg Laboratory in Uppsala, Sweden, using a 174.1 MeV neutron beam and various thicknesses of aluminum-, iron-, and copper-based shielding blocks. The results were compared to geant4 simulations and revealed excellent agreement. Our combined study highlights the particular situations where one type of metal-based solution may be preferred over another.

  3. Systematically biological prioritizing remediation sites based on datasets of biological investigations and heavy metals in soil

    Science.gov (United States)

    Lin, Wei-Chih; Lin, Yu-Pin; Anthony, Johnathen

    2015-04-01

    Heavy metal pollution has adverse effects on not only the focal invertebrate species of this study, such as reduction in pupa weight and increased larval mortality, but also on the higher trophic level organisms which feed on them, either directly or indirectly, through the process of biomagnification. Despite this, few studies regarding remediation prioritization take species distribution or biological conservation priorities into consideration. This study develops a novel approach for delineating sites which are both contaminated by any of 5 readily bioaccumulated heavy metal soil contaminants and are of high ecological importance for the highly mobile, low trophic level focal species. The conservation priority of each site was based on the projected distributions of 6 moth species simulated via the presence-only maximum entropy species distribution model followed by the subsequent application of a systematic conservation tool. In order to increase the number of available samples, we also integrated crowd-sourced data with professionally-collected data via a novel optimization procedure based on a simulated annealing algorithm. This integration procedure was important since while crowd-sourced data can drastically increase the number of data samples available to ecologists, still the quality or reliability of crowd-sourced data can be called into question, adding yet another source of uncertainty in projecting species distributions. The optimization method screens crowd-sourced data in terms of the environmental variables which correspond to professionally-collected data. The sample distribution data was derived from two different sources, including the EnjoyMoths project in Taiwan (crowd-sourced data) and the Global Biodiversity Information Facility (GBIF) ?eld data (professional data). The distributions of heavy metal concentrations were generated via 1000 iterations of a geostatistical co-simulation approach. The uncertainties in distributions of the heavy

  4. Flexible and Robust Thermoelectric Generators Based on All-Carbon Nanotube Yarn without Metal Electrodes.

    Science.gov (United States)

    Choi, Jaeyoo; Jung, Yeonsu; Yang, Seung Jae; Oh, Jun Young; Oh, Jinwoo; Jo, Kiyoung; Son, Jeong Gon; Moon, Seung Eon; Park, Chong Rae; Kim, Heesuk

    2017-08-22

    As practical interest in flexible/or wearable power-conversion devices increases, the demand for high-performance alternatives to thermoelectric (TE) generators based on brittle inorganic materials is growing. Herein, we propose a flexible and ultralight TE generator (TEG) based on carbon nanotube yarn (CNTY) with excellent TE performance. The as-prepared CNTY shows a superior electrical conductivity of 3147 S/cm due to increased longitudinal carrier mobility derived from a highly aligned structure. Our TEG is innovative in that the CNTY acts as multifunctions in the same device. The CNTY is alternatively doped into n- and p-types using polyethylenimine and FeCl 3 , respectively. The highly conductive CNTY between the doped regions is used as electrodes to minimize the circuit resistance, thereby forming an all-carbon TEG without additional metal deposition. A flexible TEG based on 60 pairs of n- and p-doped CNTY shows the maximum power density of 10.85 and 697 μW/g at temperature differences of 5 and 40 K, respectively, which are the highest values among reported TEGs based on flexible materials. We believe that the strategy proposed here to improve the power density of flexible TEG by introducing highly aligned CNTY and designing a device without metal electrodes shows great potential for the flexible/or wearable power-conversion devices.

  5. [An optical-fiber-sensor-based spectrophotometer for soil non-metallic nutrient determination].

    Science.gov (United States)

    He, Dong-xian; Hu, Juan-xiu; Lu, Shao-kun; He, Hou-yong

    2012-01-01

    In order to achieve rapid, convenient and efficient soil nutrient determination in soil testing and fertilizer recommendation, a portable optical-fiber-sensor-based spectrophotometer including immersed fiber sensor, flat field holographic concave grating, and diode array detector was developed for soil non-metallic nutrient determination. According to national standard of ultraviolet and visible spectrophotometer with JJG 178-2007, the wavelength accuracy and repeatability, baseline stability, transmittance accuracy and repeatability measured by the prototype instrument were satisfied with the national standard of III level; minimum spectral bandwidth, noise and excursion, and stray light were satisfied with the national standard of IV level. Significant linear relationships with slope of closing to 1 were found between the soil available nutrient contents including soil nitrate nitrogen, ammonia nitrogen, available phosphorus, available sulfur, available boron, and organic matter measured by the prototype instrument compared with that measured by two commercial single-beam-based and dual-beam-based spectrophotometers. No significant differences were revealed from the above comparison data. Therefore, the optical-fiber-sensor-based spectrophotometer can be used for rapid soil non-metallic nutrient determination with a high accuracy.

  6. Direct observation of shear–induced nanocrystal attachment and coalescence in CuZr-based metallic glasses: TEM investigation

    International Nuclear Information System (INIS)

    Hajlaoui, K.; Alrasheedi, Nashmi H.; Yavari, A.R.

    2016-01-01

    In-situ tensile straining tests were performed in a transmission electron microscope (TEM) to analyse the deformation processes in CuZr-based metallic glasses and to directly observe the phase transformation occurrence. We report evidence of shear induced coalescence of nanocrystals in the vicinity of deformed regions. Nanocrystals grow in shear bands, come into contact, being attached and progressively coalesce under applied shear stress. - Highlights: • In-situ tensile straining test in TEM was investigated on CuZr-Based metallic glass. • Strain induces nanocrystallization and subsequent attachment and coalescence of nanocrystals. • The coalescence of nanocrystals compensates strain softening in metallic glasses.

  7. Adsorption of aqueous metal ions on cattle-manure-compost based activated carbons.

    Science.gov (United States)

    Zaini, Muhammad Abbas Ahmad; Okayama, Reiko; Machida, Motoi

    2009-10-30

    The objective of this study is to examine the suitability and performance of cattle-manure-compost (CMC) based activated carbons in removing heavy metal ions from aqueous solution. The influence of ZnCl(2) activation ratios and solution pH on the removal of Cu(II) and Pb(II) were studied. Pore texture, available surface functional groups, pH of point zero charge (pH(PZC)), thermogravimetric analysis and elemental compositions were obtained to characterize the activated carbons. Batch adsorption technique was used to determine the metal-binding ability of activated carbons. The equilibrium data were characterized using Langmuir, Freundlich and Redlich-Peterson models. It was found that the uptake of aqueous metal ions by activated carbons could be well described by Langmuir equation. It is suggested that the increase of surface area and mesopore ratio as a result of increasing activation ratios favored the removal of Cu(II), while activated carbon rich in acidic groups showed selective adsorption towards Pb(II). The preferable removal of Cu(II) over Pb(II) could be due to the rich nitrogen content as well as the higher mesoporous surface area in the CMC activated carbons. The impregnated CMC activated carbons also showed a better performance for Cu(II) removal at varying solution pH than Filtrasorb 400 (F400), while a similar performance was observed for Pb(II) removal.

  8. Fast and scalable synthesis of uniform zirconium-, hafnium-based metal-organic framework nanocrystals.

    Science.gov (United States)

    He, Ting; Xu, Xiaobin; Ni, Bing; Wang, Haiqing; Long, Yong; Hu, Wenping; Wang, Xun

    2017-12-14

    Metal-organic frameworks based on zirconium or hafnium possess tantalizing commercial prospects due to their high stability but require a long reaction time to form crystals. The fast synthesis of uniform Zr-, Hf-MOF nanocrystals at scale is of key importance in the potential commercial application of MOFs. In this work, we have developed a versatile strategy through controlling the hydrolysis and nucleation of metal salts in the presence of acetic acid and water; up to 24 grams of UiO-66-NH 2 nanocrystals with a uniform octahedron could be synthesized within 15 minutes using a one step method. The current synthetic strategy could be extended to other Zr-, Hf-MOF nanocrystals [UiO-66-Fast, UiO-66-(OH) 2 -Fast, UiO-66-2,6-NDC-Fast, UiO-67-Fast, BUT-12-Fast, PCN-222-Ni-Fast, PCN-222-Co-Fast, Hf-UiO-66-Fast, Hf-UiO-66-NH 2 -Fast, Hf-UiO-66-(OH) 2 -Fast, Hf-UiO-66-2,6-NDC-Fast and Hf-BUT-12-Fast]. Significantly, when noble metal nanoparticles (NPs) are introduced into MOF precursors, NPs encapsulated in MOFs with excellent dispersion have also been obtained and show outstanding performance in catalysis. This facile procedure is expected to pave the way to expand the commercial applications of MOFs.

  9. Polarizing color filter based on a subwavelength metal-dielectric grating.

    Science.gov (United States)

    Ye, Yan; Zhou, Yun; Zhang, Heng; Chen, Linsen

    2011-04-01

    We propose a polarizing color filter based on a one-dimensional subwavelength metal-dielectric grating combining the functions of a polarizer and a color filter. The proposed device consists of three parts: a substrate, a dielectric grating, and a metal grating. The effects of the dielectric grating and the metal grating are investigated in detail by rigorous coupled-wave analysis. Performance is enhanced effectively by utilizing a dielectric grating of high equivalent refractive index. Typical optimized structural parameters are obtained, in which more than 72.6% broadband transmission with >21 dB polarization extinction ratio are simultaneously achieved for a tricolor filter. For transverse electric (TE) polarized light, its reflection efficiency is more than 71.8% in the broad passband light range, which can be recycled by rotating the TE polarization in part into transverse magnetic polarization and reimpinging on the designed device to increase the total energy efficiency. Numerical results show that peak transmission efficiency (PTE) is increased by at least 12.9% using recycled TE-polarized light. © 2011 Optical Society of America

  10. Correlation between local structure and stability of supercooled liquid state in Zr-based metallic glasses

    International Nuclear Information System (INIS)

    Saida, Junji; Imafuku, Muneyuki; Sato, Shigeo; Sanada, Takashi; Matsubara, Eiichiro; Inoue, Akihisa

    2007-01-01

    The correlation between the local structure and stability of supercooled liquid state is investigated in the Zr 70 (Ni, Cu) 30 binary and Zr 70 Al 10 (Ni, Cu) 20 (numbers indicate at.%) ternary metallic glasses. The Zr 70 Ni 30 binary amorphous alloy with a low stability of supercooled liquid state has a tetragonal Zr 2 Ni-like local structure around Ni atom. Meanwhile, the Zr 70 Cu 30 binary metallic glass has a different local structure of tetragonal Zr 2 Cu, where we suggest the icosahedral local structure by the quasicrystallization behavior in addition of a very small amount of noble metals. The effect of Al addition on the local structure in the Zr-Ni alloy is also examined. We have investigated that the dominant local structure changes in the icosahedral-like structure from the tetragonal Zr 2 Ni-like local structure by the Al substitution with Ni accompanying with the significant stabilization of supercooled liquid state. It is concluded that the formation of icosahedral local structure contributes to the enhancement of stability of supercooled liquid state in the Zr-based alloys

  11. A New Model for Simulating Gas Metal Arc Welding based on Phase Field Model

    Science.gov (United States)

    Jiang, Yongyue; Li, Li; Zhao, Zhijiang

    2017-11-01

    Lots of physical process, such as metal melting, multiphase fluids flow, heat and mass transfer and thermocapillary effect (Marangoni) and so on, will occur in gas metal arc welding (GMAW) which should be considered as a mixture system. In this paper, based on the previous work, we propose a new model to simulate GMAW including Navier-Stokes equation, the phase field model and energy equation. Unlike most previous work, we take the thermocapillary effect into the phase field model considering mixture energy which is different of volume of fluid method (VOF) widely used in GMAW before. We also consider gravity, electromagnetic force, surface tension, buoyancy effect and arc pressure in momentum equation. The spray transfer especially the projected transfer in GMAW is computed as numerical examples with a continuous finite element method and a modified midpoint scheme. Pulse current is set as welding current as the numerical example to show the numerical simulation of metal transfer which fits the theory of GMAW well. From the result compared with the data of high-speed photography and VOF model, the accuracy and stability of the model and scheme are easily validated and also the new model has the higher precieion.

  12. Analysis of metal contents in Portland Type V and MTA-based cements.

    Science.gov (United States)

    Dorileo, Maura Cristiane Gonçales Orçati; Bandeca, Matheus Coelho; Pedro, Fábio Luis Miranda; Volpato, Luiz Evaristo Ricci; Guedes, Orlando Aguirre; Dalla Villa, Ricardo; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique

    2014-01-01

    The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS), the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion.

  13. Analysis of Metal Contents in Portland Type V and MTA-Based Cements

    Directory of Open Access Journals (Sweden)

    Maura Cristiane Gonçales Orçati Dorileo

    2014-01-01

    Full Text Available The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS, the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P<0.05. Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion.

  14. Analysis of Metal Contents in Portland Type V and MTA-Based Cements

    Science.gov (United States)

    Dorileo, Maura Cristiane Gonçales Orçati; Bandeca, Matheus Coelho; Pedro, Fábio Luis Miranda; Volpato, Luiz Evaristo Ricci; Guedes, Orlando Aguirre; Villa, Ricardo Dalla; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique

    2014-01-01

    The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS), the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P < 0.05). Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion. PMID:25436238

  15. Biomonitoring Study of Heavy Metals in Blood from a Cement Factory Based Community

    Directory of Open Access Journals (Sweden)

    Bank M.S.

    2014-07-01

    Full Text Available Little is known about the effects of cement factory pollution, emissions, and kiln dust on contaminant exposure in human populations, including school environments, in close proximity to these point sources. In Ravena, New York, USA and vicinity, environmental pollution from a local cement plant is considered significant and substantial according to the United States Environmental Protection Agency’s Toxic Release Inventory, published in 2006, 2007, and 2010. We hypothesized that cement factory based communities, such as the one in Ravena, NY, may be differentially exposed to heavy metals, including mercury, via dust, soil, and air in addition to any contributions from fish consumption, dental amalgams, smoking habits, and occupational exposures, etc. Here we report measurements of several heavy metals in blood (Pb, Cd, As, Hg, Se and Al and, for comparative purposes, total mercury in hair from a local (six-mile radius population of Caucasian adults and children. We also report and synthesize local atmospheric emissions inventory information and new indoor air data (NYSERDA, 2011 from the local school which is situated directly across the street (within 750 feet from the cement factory and quarry. In addition, to our human and environmental heavy metal results we also discuss scientific outreach coordination, and public health action opportunities that will likely have wide applicability for other community and environmental health studies confronting similar pollution issues.

  16. Impedance-Based Battery Management for Metal-O2 Systems

    DEFF Research Database (Denmark)

    Christensen, Andreas Elkjær; Højberg, Jonathan; Norby, Poul

    2015-01-01

    In electric vehicles, reliable estimation of the state-of-charge (SoC) is crucial to determine the remaining capacity, but the electrochemical processes in metal-O2 batteries are very different to the Li-ion batteries used today, and current SoC-estimation methods prove insufficient. In Li-O2...... batteries, the capacity is highly dependent on the discharge rate, since different current densities enable different growth mechanisms of Li2O2, and an on-board calibration of the SoC is therefore needed. Such a calibration is typically performed by measuring the open-circuit voltage (OCV), but as the OCV...... of many metal-O2 battery does not change as a function of capacity, this method cannot be used. In this manuscript, we propose a method, based on a single-frequency electrochemical impedance measurement, to estimate the remaining capacity and assess the state-of-health of reversible metal-O2 batteries...

  17. Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China

    Directory of Open Access Journals (Sweden)

    Bifeng Hu

    2018-04-01

    Full Text Available Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI and Nemerow integrated pollution index (NIPI were calculated for every surface sample (0–20 cm to assess the degree of heavy metal pollution. Ordinary kriging (OK was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK. The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution.

  18. Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China.

    Science.gov (United States)

    Hu, Bifeng; Zhao, Ruiying; Chen, Songchao; Zhou, Yue; Jin, Bin; Li, Yan; Shi, Zhou

    2018-04-10

    Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn) were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI) and Nemerow integrated pollution index (NIPI) were calculated for every surface sample (0-20 cm) to assess the degree of heavy metal pollution. Ordinary kriging (OK) was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK). The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution.

  19. Shear Bond Strength of Porcelain to a Base-Metal Compared to Zirconia Core

    Directory of Open Access Journals (Sweden)

    Abrisham SM

    2017-03-01

    Full Text Available Statement of Problem: Recent clinical results for Zirconia all-ceramic restorations have revealed that the fracture rate 6-15% of the Zirconia framework is so low and the core of Zirconia has high stability. However, chipping-off fractures of porcelain are the most common reason for failures of Zirconia in the fixed partial dentures. Objectives: The purpose of this study was to compare the shear bond strength (SBS of porcelain in the porcelain fused to metal and all-ceramic crowns with Zirconia core. Materials and Methods: Two groups were selected: porcelain fused to metal (PFM and porcelain fused to Zirconia (PFZ (n = 30.In the PFM group, a wax model (10 × 10 × 10mmwas used to cast metal base (Ni_Cr alloy. In the PFZ group, an acrylic cubic model (10 × 10 × 10mm was made as Zirconia model for scanning.15 cubic Zirconia samples were milled by CAD-CAM. The procedure of porcelain veneering was conducted by the conventional layering technique up to 2 mm thickness (2.5 × 2.5 × 2 mm. All specimens were stored in water for 48 hrs. Thermal cycling was conducted for 20000 cycles between 55°C and 5ºC alternatively for 30s.All samples were mounted in acrylic resin and the SBS test was performed, using a universal testing machine. The analysis of data was performed at a significance level of 0.05 using Kolmogorov-Smirnov and Mann-Whitney U-test. Results: Mean of SBS in PFM and PFZ was 24.57 and 20.88, respectively. The results of Mann-Whitney test showed that there was no statistically significant difference between the two groups of porcelain fused to metal and Zirconia in item shear bond strength (p = 0.455. Conclusions: There was no significant difference between the two groups of PFM and PFZ in the item SBS.

  20. Shear Bond Strength of Porcelain to a Base-Metal Compared to Zirconia Core.

    Science.gov (United States)

    Abrisham, S M; Fallah Tafti, A; Kheirkhah, S; Tavakkoli, M A

    2017-03-01

    Recent clinical results for Zirconia all-ceramic restorations have revealed that the fracture rate 6-15% of the Zirconia framework is so low and the core of Zirconia has high stability. However, chipping-off fractures of porcelain are the most common reason for failures of Zirconia in the fixed partial dentures. The purpose of this study was to compare the shear bond strength (SBS) of porcelain in the porcelain fused to metal and all-ceramic crowns with Zirconia core. Two groups were selected: porcelain fused to metal (PFM) and porcelain fused to Zirconia (PFZ) (n = 30).In the PFM group, a wax model (10 × 10 × 10mm)was used to cast metal base (Ni_Cr alloy). In the PFZ group, an acrylic cubic model (10 × 10 × 10mm) was made as Zirconia model for scanning.15 cubic Zirconia samples were milled by CAD-CAM. The procedure of porcelain veneering was conducted by the conventional layering technique up to 2 mm thickness (2.5 × 2.5 × 2 mm). All specimens were stored in water for 48 hrs. Thermal cycling was conducted for 20000 cycles between 55°C and 5ºC alternatively for 30s.All samples were mounted in acrylic resin and the SBS test was performed, using a universal testing machine. The analysis of data was performed at a significance level of 0.05 using Kolmogorov-Smirnov and Mann-Whitney U-test. Mean of SBS in PFM and PFZ was 24.57 and 20.88, respectively. The results of Mann-Whitney test showed that there was no statistically significant difference between the two groups of porcelain fused to metal and Zirconia in item shear bond strength ( p = 0.455). There was no significant difference between the two groups of PFM and PFZ in the item SBS.

  1. Solar Metal Sulfate-Ammonia Based Thermochemical Water Splitting Cycle for Hydrogen Production

    Science.gov (United States)

    Huang, Cunping (Inventor); T-Raissi, Ali (Inventor); Muradov, Nazim (Inventor)

    2014-01-01

    Two classes of hybrid/thermochemical water splitting processes for the production of hydrogen and oxygen have been proposed based on (1) metal sulfate-ammonia cycles (2) metal pyrosulfate-ammonia cycles. Methods and systems for a metal sulfate MSO.sub.4--NH3 cycle for producing H2 and O2 from a closed system including feeding an aqueous (NH3)(4)SO3 solution into a photoctalytic reactor to oxidize the aqueous (NH3)(4)SO3 into aqueous (NH3)(2)SO4 and reduce water to hydrogen, mixing the resulting aqueous (NH3)(2)SO4 with metal oxide (e.g. ZnO) to form a slurry, heating the slurry of aqueous (NH4)(2)SO4 and ZnO(s) in the low temperature reactor to produce a gaseous mixture of NH3 and H2O and solid ZnSO4(s), heating solid ZnSO4 at a high temperature reactor to produce a gaseous mixture of SO2 and O2 and solid product ZnO, mixing the gaseous mixture of SO2 and O2 with an NH3 and H2O stream in an absorber to form aqueous (NH4)(2)SO3 solution and separate O2 for aqueous solution, recycling the resultant solution back to the photoreactor and sending ZnO to mix with aqueous (NH4)(2)SO4 solution to close the water splitting cycle wherein gaseous H2 and O2 are the only products output from the closed ZnSO4--NH3 cycle.

  2. Shear bond strength of a ceromer to noble and base metal alloys

    Directory of Open Access Journals (Sweden)

    Dorriz H.

    2006-08-01

    Full Text Available Background and Aim: The improvement of the physical and chemical properties of resins as well as great advances achieved in the field of chemical bonding of resin to metal has changed the trend of restorative treatments. Today the second generation of laboratory resins have an important role in the restoration of teeth. The clinical bond strength should be reliable in order to gain successful results. In this study the shear bond strength (SBS between targis (a ceromer and two alloys (noble and base metal was studied and the effect of thermocycling on the bond investigated. Materials and Methods: In this experimental study, alloys samples were prepared according to the manufacturer. After sandblasting of bonding surfaces with 50µ AI2o3 Targis was bonded to the alloy using Targis I link. All of the samples were placed in 37°C water for a period of 24 hours. Then half of the samples were subjected to 1000 cycles of thermocycling at temperatures of 5°C and 55°C. Planear shear test was used to test the bond strength in the Instron machine with the speed rate of 0.5mm/min. Data were analyzed by SPSS software. Two-way analysis of variance was used to compare the bond strength among the groups. T test was used to compare the alloys. The influence of thermocycling and alloy type on bond strength was studied using Mann Whitney test. P<0.05 was considered as the limit of significance. Result: The studied alloys did not differ significantly, when the samples were not thermocycled (P=0.136 but after thermocycling a significant difference was observed in SBS of resin to different alloys (P=000.1. Thermal stress and alloy type had significant interaction, with regard to shear bond strength (P=0.003. There was a significant difference in SBS before and after thermocycling in noble alloys (P=0.009, but this was not true in base metals (P=0.29. Maximum SBS (19.09 Mpa belonged to Degubond 4, before thermocycling. Minimum SBS (8.21 Mpa was seen in Degubond 4

  3. Manipulating fluorescence color and intensity with regular metal nanoparticle-based composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, Andrey G., E-mail: nikitin@cinam.univ-mrs.fr [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM, UPR 3118 CNRS), Aix-Marseille University, Campus de Luminy, Case 913, 13288 Marseille, France and Faculty of Physics and Technology, Al-Farabi Kazakh National University, 71 Al-Farabi Ave., 050040 Almaty (Kazakhstan)

    2016-02-01

    This paper first studies the role of structural parameters of ordered metal nanoparticle-based composites in the modification of the spectra and intensity of directional emission from organic molecules. It then investigates the possibilities of white light generation via color conversion using two materials, one emitting in the green and the other one in the red spectral region. The structures under study exhibit enhanced emission within small solid angle in the forward direction due to excitation of the quasiguided modes. These modes modify the angle-dependent local photon density of states and, thus, result in efficient directional outcoupling of radiation.

  4. Electrical Switching in Thin Film Structures Based on Transition Metal Oxides

    Directory of Open Access Journals (Sweden)

    A. Pergament

    2015-01-01

    Full Text Available Electrical switching, manifesting itself in the nonlinear current-voltage characteristics with S- and N-type NDR (negative differential resistance, is inherent in a variety of materials, in particular, transition metal oxides. Although this phenomenon has been known for a long time, recent suggestions to use oxide-based switching elements as neuristor synapses and relaxation-oscillation circuit components have resumed the interest in this area. In the present review, we describe the experimental facts and theoretical models, mainly on the basis of the Mott transition in vanadium dioxide as a model object, of the switching effect with special emphasis on the emerging applied potentialities for oxide electronics.

  5. Recent Advances in Electronic and Optoelectronic Devices Based on Two-Dimensional Transition Metal Dichalcogenides

    Directory of Open Access Journals (Sweden)

    Mingxiao Ye

    2017-06-01

    Full Text Available Two-dimensional transition metal dichalcogenides (2D TMDCs offer several attractive features for use in next-generation electronic and optoelectronic devices. Device applications of TMDCs have gained much research interest, and significant advancement has been recorded. In this review, the overall research advancement in electronic and optoelectronic devices based on TMDCs are summarized and discussed. In particular, we focus on evaluating field effect transistors (FETs, photovoltaic cells, light-emitting diodes (LEDs, photodetectors, lasers, and integrated circuits (ICs using TMDCs.

  6. Gas metal arc welding of butt joint with varying gap width based on neural networks

    DEFF Research Database (Denmark)

    Christensen, Kim Hardam; Sørensen, Torben

    2005-01-01

    This paper describes the application of the neural network technology for gas metal arc welding (GMAW) control. A system has been developed for modeling and online adjustment of welding parameters, appropriate to guarantee a certain degree of quality in the field of butt joint welding with full...... penetration, when the gap width is varying during the welding process. The process modeling to facilitate the mapping from joint geometry and reference weld quality to significant welding parameters, has been based on a multi-layer feed-forward network. The Levenberg-Marquardt algorithm for non-linear least...

  7. Facile creation of bio-inspired superhydrophobic Ce-based metallic glass surfaces

    Science.gov (United States)

    Liu, Kesong; Li, Zhou; Wang, Weihua; Jiang, Lei

    2011-12-01

    A bio-inspired synthesis strategy was conducted to fabricate superhydrophobic Ce-based bulk metallic glass (BMG) surfaces with self-cleaning properties. Micro-nanoscale hierarchical structures were first constructed on BMG surfaces and then modified with the low surface energy coating. Surface structures, surface chemical compositions, and wettability were characterized by combining scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and contact angle measurements. Research indicated that both surface multiscale structures and the low surface free energy coating result in the final formation of superhydrophobicity.

  8. Hierarchical Pore Development by Plasma Etching of Zr-Based Metal-Organic Frameworks.

    Science.gov (United States)

    DeCoste, Jared B; Rossin, Joseph A; Peterson, Gregory W

    2015-12-07

    The typically stable Zr-based metal-organic frameworks (MOFs) UiO-66 and UiO-66-NH2 were treated with tetrafluoromethane (CF4 ) and hexafluoroethane (C2 F6 ) plasmas. Through interactions between fluoride radicals from the perfluoroalkane plasma and the zirconium-oxygen bonds of the MOF, the resulting materials showed the development of mesoporosity, creating a hierarchical pore structure. It is anticipated that this strategy can be used as a post-synthetic technique for developing hierarchical networks in a variety of MOFs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Thermodynamic and structural basis for electrochemical response of Cu–Zr based metallic glass

    International Nuclear Information System (INIS)

    Zhang, Chunzhi; Qiu, Nannan; Kong, Lingliang; Yang, Xiaodan; Li, Huiping

    2015-01-01

    Highlights: • Thermodynamic and structural basis for electrochemical response were proposed. • La improves the corrosion resistance by inhibition of the selective dissolution. • Corrosion of the MG responses well with thermodynamic and structural parameters. - Abstract: Cu–Zr based metallic glasses were prepared by hyperquenching strategy to explore the thermodynamic and structural basis for electrochemical response. The thermodynamic parameters and the local atomic structure were obtained. Corrosion resistance in seawater was investigated via potentiodynamic polarization curve. The results indicate that increasing thermodynamic parameter values improves the corrosion resistance. The topological instability represented by the nearest neighbor atomic distance yields same tendency as the corrosion resistance with La addition

  10. Theoretical study of metal ion binding in modified and natural cytosine-cytosine base pairs

    Czech Academy of Sciences Publication Activity Database

    Šebera, Jakub; Sugiyama, K.; Ono, A.; Mulder, J.; Bickelhaupt, F. M.; Tanaka, Y.; Sychrovský, Vladimír; Guerra, C. F.

    2013-01-01

    Roč. 20, č. 1 (2013), s. 39-39 ISSN 1211-5894. [Discussions in Structural Molecular Biology. Annual Meeting of the Czech Society for Structural Biology /11./. 14.03.2013-16.03.2013, Nové Hrady] R&D Projects: GA ČR GAP205/10/0228; GA ČR(CZ) GAP304/10/1951; GA TA ČR TA01011165 Institutional support: RVO:61388963 Keywords : DFT * NMR * base pair * metal-mediated Subject RIV: CF - Physical ; Theoretical Chemistry

  11. Atomic polar tensors and acid-base properties of metal-oxide building blocks

    International Nuclear Information System (INIS)

    Ferris, K.F.

    1993-02-01

    The sensitivity of the atomic polar tensor to compositional substituents is reported for the alkali silicate series. Rotational invariants, effective atomic charge (GAPT) and charge normalized anisotropy and dipole (α n and γ n ) are used to characterize the charge distribution and chemical environment of the atomic sites. Comparison of α n and γ n with a series of known Bronsted and Lewis acids and bases suggests that these rotational invariants may act as indicators for metal-oxide site acidities. Basis set and electron correlation particularly affect the determined effective charge, but show minimal effect on α and γ quantities

  12. Endothelial cell activation, oxidative stress and inflammation induced by a panel of metal-based nanomaterials

    DEFF Research Database (Denmark)

    Danielsen, Pernille Høgh; Cao, Yi; Roursgaard, Martin

    2015-01-01

    The importance of composition, size, crystal structure, charge and coating of metal-based nanomaterials (NMs) were evaluated in human umbilical vein endothelial cells (HUVECs) and/or THP-1 monocytic cells. Biomarkers of oxidative stress and inflammation were assessed because they are important...... in the development of cardiovascular diseases. The NMs used were five TiO2 NMs with different charge, size and crystal structure, coated and uncoated ZnO NMs and Ag which were tested in a wide concentration range. There were major differences between the types of NMs; exposure to ZnO and Ag resulted in cytotoxicity...

  13. Toxicities and risk assessment of heavy metals in sediments of Taihu Lake, China, based on sediment quality guidelines.

    Science.gov (United States)

    Zhang, Yanfeng; Han, Yuwei; Yang, Jinxi; Zhu, Lingyan; Zhong, Wenjue

    2017-12-01

    The occurrence, toxicities, and ecological risks of five heavy metals (Pb, Cu, Cd, Zn and Ni) in the sediment of Taihu Lake were investigated in this study. To evaluate the toxicities caused by the heavy metals, the toxicities induced by organic contaminants and ammonia in the sediments were screened out with activated carbon and zeolite. The toxicities of heavy metals in sediments were tested with benthic invertebrates (tubificid and chironomid). The correlations between toxicity of sediment and the sediment quality guidelines (SQGs) derived previously were evaluated. There were significant correlations (pheavy metals based on SQGs, indicating that threshold effect level (TEL) and probable effect level (PEL) were reliable to predict the toxicities of heavy metals in the sediments of Taihu Lake. By contrast, the method based on acid volatile sulfides (AVS) and simultaneously extracted metals (SEM), such as ∑SEM/AVS and ∑SEM-AVS, did not show correlations with the toxicities. Moreover, the predictive ability of SQGs was confirmed by a total predicting accuracy of 77%. Ecological risk assessment based on TELs and PELs showed that the contaminations of Pb, Cu, Cd and Zn in the sediments of Taihu Lake were at relatively low or medium levels. The risks caused by heavy metals in the sediments of northern bay of the lake, which received more wastewater discharge from upper stream, were higher than other area of the lake. Copyright © 2017. Published by Elsevier B.V.

  14. PVC-based composite material containing recycled non-metallic printed circuit board (PCB) powders.

    Science.gov (United States)

    Wang, Xinjie; Guo, Yuwen; Liu, Jingyang; Qiao, Qi; Liang, Jijun

    2010-12-01

    The study is directed to the use of non-metallic powders obtained from comminuted recycled paper-based printed circuit boards (PCBs) as an additive to polyvinyl chloride (PVC) substrate. The physical properties of the non-metallic PCB (NMPCB) powders were measured, and the morphological, mechanical and thermal properties of the NMPCB/PVC composite material were investigated. The results show that recycled NMPCB powders, when added below a threshold, tended to increase the tensile strength and bending strength of PVC. When 20 wt% NMPCB powders (relative to the substrate PVC) of an average diameter of 0.08 mm were added, the composite tensile strength and bending strength reached 22.6 MPa and 39.83 MPa, respectively, representing 107.2% and 123.1% improvement over pure PVC. The elongation at break of the composite material reached 151.94% of that of pure PVC, while the Vicat softening temperature of the composite material did not increase significantly compared to the pure PVC. The above results suggest that paper-based NMPCB powders, when used at appropriate amounts, can be effective for toughening PVC. Thus, this study suggests a new route for reusing paper-based NMPCB, which may have a significant beneficial environmental impact. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. The supercooled liquid region span of Fe-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ferenc, Jaroslaw, E-mail: jferenc@inmat.pw.edu.p [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw (Poland); Erenc-Sedziak, Tatiana; Kowalczyk, Maciej; Kulik, Tadeusz [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw (Poland)

    2010-04-16

    This work presents the results of the study of the magnetically soft, iron-based bulk metallic glasses, from the viewpoint of their ability to deform in the supercooled liquid region and to resist the tendency to crystallise. The calorimetric measurements of glass transition and crystallisation temperatures (T{sub g} and T{sub x1} respectively) were employed, accompanied by the measurements of magnetic properties as the monitor of structural changes after heat treatment. It was found that the widest supercooled liquid region was obtained when zirconium was selected as one of the alloying elements, yielding the T{sub x1}-T{sub g} span of about 70 {sup o}C. Also, it was observed that the values of T{sub g} and T{sub x} may be controlled by the proportions of the main elements (Fe, Co, Ni), and the glass forming elements (such as B, Nb, Zr). As a guideline, it is suggested that the glassy Fe-based alloys may be maintained in the supercooled liquid state without crystallisation for several minutes, if T{sub x1}-T{sub g} is wider than 50 {sup o}C. Basing on this estimation, calorimetric measurements may be a good indicator of the ability of bulk metallic glasses to be suitable for superplastic compaction into larger shapes.

  16. Comparison of Shear Bond Strengths of three resin systems for a Base Metal Alloy bonded to

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

    Full Text Available Resin-bonded fixed partial dentures (F.P.D can be used for conservative treatment of partially edentulous"npatients. There are numerous studies regarding the strength of resin composite bond to base meta! alloys. Shear bond"nstrength of three resin systems were invistigated. In this study these systems consisted of: Panavia Ex, Mirage FLC and"nMarathon V. Thirty base metal specimens were prepared from rexillium III alloy and divided into three groups. Then each"ngroup was bonded to enamel of human extracted molar teeth with these systems. All of specimens were stored in water at"n37ac for 48 hours. A shear force was applied to each specimen by the instron universal testing machine. A statistical"nevaluation of the data using one-way analysis of variance showed that there was highly significant difference (P<0.01"nbetween the bond strengths of these three groups."nThe base metal specimens bonded with panavia Ex luting agent, exhibited the highest mean bond strength. Shear bond"nstrength of the specimens bonded to enamel with Mirage F1C showed lower bond strenght than panavia EX. However, the"nlowest bond strength was obtained by the specimens bonded with Marathon V.

  17. Additive Manufacturing of H11 with Wire-Based Laser Metal Deposition

    Directory of Open Access Journals (Sweden)

    Stella Holzbach Oliari

    2017-12-01

    Full Text Available Abstract Laser additive manufacturing (LAM is a near-net-shape production technique by which a part can be built up from 3D CAD model data, without material removal. Recently, these production processes gained attention due to the spreading of polymer-based processes in private and commercial applications. However, due to the insufficient development of metal producing processes regarding design, process information and qualification, resistance on producing functional components with this technology is still present. To overcome this restriction further studies have to be undertaken. The present research proposes a parametric study of additive manufacturing of hot work tool steel, H11. The selected LAM process is wire-based laser metal deposition (LMD-W. The study consists of parameters optimization for single beads (laser power, travel speed and wire feed rate as well as lateral and vertical overlap for layer-by-layer technique involved in LMD process. Results show that selection of an ideal set of parameters affects substantially the surface quality, bead uniformity and bond between substrate and clad. Discussion includes the role of overlapping on the soundness of parts based on the height homogeneity of each layer, porosity and the presence of gaps. For the conditions tested it was shown that once the deposition parameters are selected, lateral and vertical overlapping determines the integrity and quality of parts processed by LAM.

  18. Highly Conductive, Transparent Flexible Films Based on Metal Nanoparticle-Carbon Nanotube Composites

    Directory of Open Access Journals (Sweden)

    Wen-Yin Ko

    2013-01-01

    Full Text Available Metallic nanoparticles decorated on MWCNTs based transparent conducting thin films (TCFs show a cheap and efficient option for the applications in touch screens and the replacement of the ITO film because of their interesting properties of electrical conductivity, mechanical property, chemical inertness, and other unique properties, which may not be accessible by their individual components. However, a great challenge that always remains is to develop effective ways to prepare junctions between metallic nanoparticles and MWCNTs for the improvement of high-energy barriers, high contact resistances, and weak interactions which could lead to the formation of poor conducting pathways and result in the CNT-based devices with low mechanical flexibility. Herein, we not only discuss recent progress in the preparation of MNP-CNT flexible TCFs but also describe our research studies in the relevant areas. Our result demonstrated that the MNP-CNT flexible TCFs we prepared could achieve a highly electrical conductivity with the sheet resistance of ~100 ohm/sq with ~80% transmittance at 550 nm even after being bent 500 times. This electrical conductivity is much superior to the performances of other MWCNT-based transparent flexible films, making it favorable for next-generation flexible touch screens and optoelectronic devices.

  19. Chemical Reactions Catalyzed by Metalloporphyrin-Based Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Kelly Aparecida Dias de Freitas Castro

    2013-06-01

    Full Text Available The synthetic versatility and the potential application of metalloporphyrins (MP in different fields have aroused researchers’ interest in studying these complexes, in an attempt to mimic biological systems such as cytochrome P-450. Over the last 40 years, synthetic MPs have been mainly used as catalysts for homogeneous or heterogeneous chemical reactions. To employ them in heterogeneous catalysis, chemists have prepared new MP-based solids by immobilizing MP onto rigid inorganic supports, a strategy that affords hybrid inorganic-organic materials. More recently, materials obtained by supramolecular assembly processes and containing MPs as building blocks have been applied in a variety of areas, like gas storage, photonic devices, separation, molecular sensing, magnets, and heterogeneous catalysis, among others. These coordination polymers, known as metal-organic frameworks (MOFs, contain organic ligands or complexes connected by metal ions or clusters, which give rise to a 1-, 2- or 3-D network. These kinds of materials presents large surface areas, Brønsted or redox sites, and high porosity, all of which are desirable features in catalysts with potential use in heterogeneous phases. Building MOFs based on MP is a good way to obtain solid catalysts that offer the advantages of bioinspired systems and zeolitic materials. In this mini review, we will adopt a historical approach to present the most relevant MP-based MOFs applicable to catalytic reactions such as oxidation, reduction, insertion of functional groups, and exchange of organic functions.

  20. A versatile MOF-based trap for heavy metal ion capture and dispersion.

    Science.gov (United States)

    Peng, Yaguang; Huang, Hongliang; Zhang, Yuxi; Kang, Chufan; Chen, Shuangming; Song, Li; Liu, Dahuan; Zhong, Chongli

    2018-01-15

    Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd 2+ -loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.

  1. Verification of Structural Simulation Results of Metal-based Additive Manufacturing by Means of Neutron Diffraction

    Science.gov (United States)

    Krol, T. A.; Seidel, C.; Schilp, J.; Hofmann, M.; Gan, W.; Zaeh, M. F.

    Metal-based additive processes are characterized by numerous transient physical effects, which exhibit an adverse influence on the production result. Hence, various research approaches for the optimization of e. g. the structural part behavior exist for layered manufacturing. Increasingly, these approaches are based on the finite element analysis to be able to understand the complexity. Hereby it should be considered that the significance of the calculation results depends on the quality of modeling the process in the simulation environment. Based on a selected specimen, the current work demonstrates in which way the numerical accuracy of the residual stress state can be analyzed by utilizing the neutron diffraction. Thereby, different process parameter settings were examined.

  2. Rational Design of Two-Dimensional Metallic and Semiconducting Spintronic Materials Based on Ordered Double-Transition-Metal MXenes

    KAUST Repository

    Dong, Liang

    2016-12-30

    Two-dimensional (2D) materials that display robust ferromagnetism have been pursued intensively for nanoscale spintronic applications, but suitable candidates have not been identified. Here we present theoretical predictions on the design of ordered double-transition-metal MXene structures to achieve such a goal. On the basis of the analysis of electron filling in transition-metal cations and first-principles simulations, we demonstrate robust ferromagnetism in Ti2MnC2Tx monolayers regardless of the surface terminations (T = O, OH, and F), as well as in Hf2MnC2O2 and Hf2VC2O2 monolayers. The high magnetic moments (3–4 μB/unit cell) and high Curie temperatures (495–1133 K) of these MXenes are superior to those of existing 2D ferromagnetic materials. Furthermore, semimetal-to-semiconductor and ferromagnetic-to-antiferromagnetic phase transitions are predicted to occur in these materials in the presence of small or moderate tensile in-plane strains (0–3%), which can be externally applied mechanically or internally induced by the choice of transition metals.

  3. Kinetics of heavy metal adsorption and desorption in soil: Developing a unified model based on chemical speciation

    Science.gov (United States)

    Peng, Lanfang; Liu, Paiyu; Feng, Xionghan; Wang, Zimeng; Cheng, Tao; Liang, Yuzhen; Lin, Zhang; Shi, Zhenqing

    2018-03-01

    Predicting the kinetics of heavy metal adsorption and desorption in soil requires consideration of multiple heterogeneous soil binding sites and variations of reaction chemistry conditions. Although chemical speciation models have been developed for predicting the equilibrium of metal adsorption on soil organic matter (SOM) and important mineral phases (e.g. Fe and Al (hydr)oxides), there is still a lack of modeling tools for predicting the kinetics of metal adsorption and desorption reactions in soil. In this study, we developed a unified model for the kinetics of heavy metal adsorption and desorption in soil based on the equilibrium models WHAM 7 and CD-MUSIC, which specifically consider metal kinetic reactions with multiple binding sites of SOM and soil minerals simultaneously. For each specific binding site, metal adsorption and desorption rate coefficients were constrained by the local equilibrium partition coefficients predicted by WHAM 7 or CD-MUSIC, and, for each metal, the desorption rate coefficients of various binding sites were constrained by their metal binding constants with those sites. The model had only one fitting parameter for each soil binding phase, and all other parameters were derived from WHAM 7 and CD-MUSIC. A stirred-flow method was used to study the kinetics of Cd, Cu, Ni, Pb, and Zn adsorption and desorption in multiple soils under various pH and metal concentrations, and the model successfully reproduced most of the kinetic data. We quantitatively elucidated the significance of different soil components and important soil binding sites during the adsorption and desorption kinetic processes. Our model has provided a theoretical framework to predict metal adsorption and desorption kinetics, which can be further used to predict the dynamic behavior of heavy metals in soil under various natural conditions by coupling other important soil processes.

  4. Transient performance of a thermal energy storage-based heat sink using a liquid metal as the phase change material

    International Nuclear Information System (INIS)

    Fan, Li-Wu; Wu, Yu-Yue; Xiao, Yu-Qi; Zeng, Yi; Zhang, Yi-Ling; Yu, Zi-Tao

    2016-01-01

    Highlights: • A liquid metal is adopted as the PCM in a thermal energy storage-based heat sink. • Transient performance of the heat sink is tested in comparison to an organic PCM. • The liquid metal has a similar volumetric latent heat of fusion to the organic PCM. • Outperformance of the liquid metal is found due to its higher thermal conductivity. • Liquid metals are preferred when the system weight is less important than volume. - Abstract: In this Technical Note, the use of a liquid metal, i.e., a low melting point Pb–Sn–In–Bi alloy, as the phase change material (PCM) in thermal energy storage-based heat sinks is tested in comparison to an organic PCM (1-octadecanol) having a similar melting point of ∼60 °C. The thermophysical properties of the two types of PCM are characterized, revealing that the liquid metal is much more conductive while both have nearly identical volumetric latent heat of fusion (∼215 MJ/m 3 ). By using at the same volume of 80 mL, i.e., the same energy storage capacity, the liquid metal is shown to outperform significantly over the organic PCM under the various heating powers up to 105.3 W/cm 2 . During the heating period, the use of the liquid metal leads to a remarkable extension of the effective protection time to nearly twice longer as well as a reduction of the highest overheating temperature by up to 50 °C. The cool-down period can also be shortened significantly by taking advantage of the much higher thermal conductivity of the liquid metal. These findings suggest that liquid metals could serve as a promising PCM candidate for particular applications where the volume limit is very rigorous and the penalty in weight increment is acceptable.

  5. Metal-based nanoparticle interactions with the nervous system: The challenge of brain entry and the risk of retention in the organism

    Science.gov (United States)

    This review of metal and metal-oxide based nanoparticles focuses on factors that influence their distribution into the nervous system, evidence that they enter brain parenchyma, and nervous system responses. Emphasis is placed on gold as a model metal-based nanoparticle and for r...

  6. Resorcarene-based receptor: versatile behavior in its interaction with heavy and soft metal cations.

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K; Piro, Oscar E; Castellano, Eduardo E

    2006-02-09

    Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal

  7. Metal-glass based composites for application in TBC-systems

    Science.gov (United States)

    Mack, D. E.; Vaßen, R.; Stöver, D.; Gross, S. M.

    2006-12-01

    A new type of thermal barrier coating (TBC) based on metal-glass composite (MGC) consisting of an ordinary container glass and a NiCoCrAlY-alloy has been recently presented. This TBC material provides the possibility to easily adjust its thermal expansion coefficient to match the substrate by changing the metal to glass ratio of the composite. Vacuum plasma spraying (VPS) has been applied as a possible technologies for deposition of MGC coatings. Isothermal oxidation tests were carried out in air at temperatures of 950, 1000, and 1050 °C, respectively. Thermal cycling tests were carried out by applying a temperature gradient across the sample thickness by heating with an open flame of natural gas followed by removal of the burner and air cooling. Changes in the microstructure were examined by means of microscopy, microanalysis, and x-ray powder diffraction. For long-time annealing at high temperatures, a progressive degradation of the glass matrix as well as oxidation of the metal phases cannot be fully suppressed up to now. By lowering the effective temperature at the MGC layer when used as an intermediate layer, the degradation of the MGC can be reduced without losing its advanced features with respect to creeping and gas-tightness. Additional concepts for improved oxidation resistance of the MGC based on suitable heat treatments and on alternative glass compositions have been developed, and primary results are shown. Evaluation of results from isothermal oxidation experiments and from thermal cycling in burner-rig facilities validates a clear improvement of the lifetime of the coatings compared with earlier results.

  8. Atmospheric metal deposition in France: Estimation based on moss analysis. First results

    International Nuclear Information System (INIS)

    Galsomies, L.; Letrouit-Galinou, M.A.; Avnaim, M.; Duclaux, G.; Deschamps, C.; Savanne, D.

    2000-01-01

    The aim of this programme set up by University Pierre and Marie Curie-Paris VI and ADEME (French Agency for the Environment and Energy Management) is to obtain information on the atmospheric deposition of 36 elements (most being heavy metals) all over France, using 5 common mosses as bioaccumulators: Pleurozium schreberi, Hylocomium splendens, Hypnum cupressiforme, Scleropodium purum and Thuidium tamariscinum. Sampling was performed in 1996 from April to November thanks to 43 collectors. One sample of moss at least has been collected in 512 sites distributed over France, with an average density of one site each 1000 km 2 . Procedures for sampling, drying, cleaning, sorting are strictly codified based on Scandinavian guidelines. Analyses are performed according to two procedures: ICP-MS (Inductively Coupled Plasma, Mass Spectrometry) for Pb, Ni specialty and INAA (instrumental Neutron Activation Analysis for other elements. Data concerning As, Cd, Cr, Cu, Fe, Hg, Pb. Ni, V, Zn will be incorporated into the 1995-1996 European Programme 'Atmospheric Heavy Metal Deposition in Europe - estimation based on moss analysis' coordinated by the Nordic Council. The analyses are in progress, but preliminary results from Ile-de-France have been achieved for 34 elements in INAA. A preliminary study has shown that interspecies calibration could be possible for some heavy metals and that saturation effects in one species could be present when the intercalibration between species is not possible. Such a programme is made possible thanks to the financial support of the French Ministry of Environment and ADEME and with the active cooperation of several national organisations, especially the Laboratory Pierre Sue (CNRS-CEA). (author)

  9. Dynamically controllable plasmon induced transparency based on hybrid metal-graphene metamaterials.

    Science.gov (United States)

    Yan, Xicheng; Wang, Tao; Xiao, Shuyuan; Liu, Tingting; Hou, Haowen; Cheng, Le; Jiang, Xiaoyun

    2017-10-24

    Novel hybrid metal-graphene metamaterials featuring dynamically controllable single, double and multiple plasmon induced transparency (PIT) windows are numerically explored in the terahertz (THz) regime. The designed plasmonic metamaterials composed of a strip and a ring with graphene integration generate a novel PIT window. Once the ring is divided into pairs of asymmetrical arcs, double PIT windows both with the spectral contrast ratio 100% are obtained, where one originates from the destructive interference between bright-dark modes, and the other is based on the interaction of bright-bright modes. Just because the double PIT windows are induced by two different mechanisms, the continuously controllable conductivity and damping of graphene are employed to appropriately interpret the high tunability in double transparency peaks at the resonant frequency, respectively. Moreover, multiple PIT windows can be achieved by introducing an additional bright mode to form the other bright-bright modes coupling. At the PIT transparent windows, the dispersions undergo tremendous modifications and the group delays reach up to 43 ps, 22 ps, and 25 ps, correspondingly. Our results suggest the existence of strong interaction between the monolayer graphene layer and metal-based resonant plasmonic metamaterials, which may hold widely applications in filters, modulators, switching, sensors and optical buffers.

  10. Catalytic Transfer Hydrogenation of Biomass-Derived Carbonyls over Hafnium-Based Metal-Organic Frameworks.

    Science.gov (United States)

    Rojas-Buzo, Sergio; García-García, Pilar; Corma, Avelino

    2018-01-23

    A series of highly crystalline, porous, hafnium-based metal-organic frameworks (Hf-MOFs) have been shown to catalyze the transfer hydrogenation reaction of levulinic ester to produce γ-valerolactone by using isopropanol as a hydrogen donor. The results are compared with their zirconium-based counterparts. The role of the metal center in Hf-MOFs has been identified and reaction parameters optimized. NMR studies using isotopically labeled isopropanol provide evidence that the transfer hydrogenation occurs through a direct intermolecular hydrogen transfer route. The catalyst, Hf-MOF-808, can be recycled several times with only a minor decrease in catalytic activity. The generality of the procedure has been demonstrated by accomplishing the transformation with aldehydes, ketones, and α,β-unsaturated carbonyl compounds. The combination of Hf-MOF-808 with the Brønsted-acidic Al-Beta zeolite gives the four-step one-pot transformation of furfural to γ-valerolactone in good yield of 75 %. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Influence of alkali metal hydroxides on corrosion of Zr-based alloys

    International Nuclear Information System (INIS)

    Jeong, Y.H.; Ruhmann, H.; Garzarolli, F.

    1997-01-01

    In this study the influence of group-1 alkali hydroxides on different zirconium based alloys has been evaluated. The experiments have been carried out in small stainless steel autoclaves at 350 deg. C in pressurized 17 MPa water, with in low (0.32 mmol), medium (4.3 mmol) and high (31.5 mmol) equimolar concentrations of Li-, Na-, K-, Rb- and Cs-Hydroxides. Two types of alloys have been investigated: Zr-Sn-(Transition metal) and Zr-Sn-Nb-(Transition metal). The corrosion behaviour was evaluated from weight gain measurements. From the experiments the cation could be identified as the responsible species for zirconium alloy corrosion in alkalized water. The radius of the cation governs the corrosion behaviour in the pre accelerated region of zircaloy corrosion. Incorporating of alkali cations into the zirconium oxide lattice is probably the mechanism which allows the corrosion enhancement for Li and Na and the significantly lower effect for the other bases. Nb containing alloys show lower corrosion resistance than alloys from the Zr-Sn-TRM system in all alkali solutions. Both types of alloys corrode significantly more in LiOH and NaOH than in the other alkali environments. Lowest corrosive aggressiveness has been found for CsOH followed by KOH. Concluding from the corrosion behaviour in the different alkali environments and taking into account the tendency to promote accelerate corrosion, CsOH and KOH are possible alternate alkalis for PWR application. (author). 17 refs, 15 figs, 5 tabs

  12. Paper-Based Sensor Chip for Heavy Metal Ion Detection by SWSV

    Directory of Open Access Journals (Sweden)

    Xiaoqing Wang

    2018-03-01

    Full Text Available Heavy metal ion pollution problems have had a terrible influence on human health and the environment. Therefore, the monitoring of heavy metal ions is of great practical significance. In this paper, an electrochemical three-electrode system was fabricated and integrated on nitrocellulose membrane (NC by the use of magnetron sputtering technology, which exhibited a uniform arrangement of porous structure without further film modification. This paper-based sensor chip was used for Cu2+ detection by square-wave stripping voltammetry (SWSV. Within the ranges of 5~200 μg·L−1 and 200~1000 μg·L−1, it showed good linearity of 99.58% and 98.87%, respectively. The limit of detection was 2 μg·L−1. On the basis of satisfying the detection requirements (10 μg·L−1, the integrated sensor was small in size and inexpensive in cost. Zn2+, Cd2+, Pb2+ and Bi3+ were also detected by this paper-based sensor chip with good linearity.

  13. Standardized hydrogen storage module with high utilization factor based on metal hydride-graphite composites

    Science.gov (United States)

    Bürger, Inga; Dieterich, Mila; Pohlmann, Carsten; Röntzsch, Lars; Linder, Marc

    2017-02-01

    In view of hydrogen based backup power systems or small-scale power2gas units, hydrogen storages based on metal hydrides offer a safe and reliable solution. By using Hydralloy C5 as suitable hydride forming alloy, the present tank design guarantees very simple operating conditions: pressures between 4 bar and 30 bar, temperatures between 15 °C and 40 °C and minimal efforts for thermal management in combination with fast and constant charging and discharging capabilities. The modular tank consists of 4 layers with 5 reactor tubes each that are filled with metal hydride-graphite composites of a diameter of 21 mm. Experiments show that each layer of this tank is able to desorb the desired amount of hydrogen for a fuel cell operation at electrical power of 160 Wel for 100 min reaching a utilization factor of 93% of the stored hydrogen at RC. Furthermore, the experimental results of modularity, increasing loads and the electric air ventilation are presented.

  14. Recent advances in metal oxide-based electrode architecture design for electrochemical energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jian; Liu, Jinping; Huang, Xintang [Institute of Nanoscience and Nanotechnology, Department of Physics, Central China Normal University, Wuhan, Hubei (China); Li, Yuanyuan [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan (China); Yuan, Changzhou; Lou, Xiong Wen [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore (China)

    2012-10-02

    Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part ''how to design superior electrode architectures''. In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Recent advances in metal oxide-based electrode architecture design for electrochemical energy storage.

    Science.gov (United States)

    Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang; Yuan, Changzhou; Lou, Xiong Wen David

    2012-10-02

    Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part "how to design superior electrode architectures". In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Mechanical behavior of polymer-basedvs. metallic-based bioresorbable stents.

    Science.gov (United States)

    Ang, Hui Ying; Huang, Ying Ying; Lim, Soo Teik; Wong, Philip; Joner, Michael; Foin, Nicolas

    2017-08-01

    Bioresorbable scaffolds (BRS) were developed to overcome the drawbacks of current metallic drug-eluting stents (DES), such as late in-stent restenosis and caging of the vessel permanently. The concept of the BRS is to provide transient support to the vessel during healing before being degraded and resorbed by the body, freeing the vessel and restoring vasomotion. The mechanical properties of the BRS are influenced by the choice of the material and processing methods. Due to insufficient radial strength of the bioresorbable material, BRS often required large strut profile as compared to conventional metallic DES. Having thick struts will in turn affect the deliverability of the device and may cause flow disturbance, thereby increasing the incidence of acute thrombotic events. Currently, the bioresorbable poly-l-lactic acid (PLLA) polymer and magnesium (Mg) alloys are being investigated as materials in BRS technologies. The bioresorption process, mechanical properties, in vitro observations and clinical outcomes of PLLA-based and Mg-based BRS will be examined in this review.

  17. Metal oxide resistive random access memory based synaptic devices for brain-inspired computing

    Science.gov (United States)

    Gao, Bin; Kang, Jinfeng; Zhou, Zheng; Chen, Zhe; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan

    2016-04-01

    The traditional Boolean computing paradigm based on the von Neumann architecture is facing great challenges for future information technology applications such as big data, the Internet of Things (IoT), and wearable devices, due to the limited processing capability issues such as binary data storage and computing, non-parallel data processing, and the buses requirement between memory units and logic units. The brain-inspired neuromorphic computing paradigm is believed to be one of the promising solutions for realizing more complex functions with a lower cost. To perform such brain-inspired computing with a low cost and low power consumption, novel devices for use as electronic synapses are needed. Metal oxide resistive random access memory (ReRAM) devices have emerged as the leading candidate for electronic synapses. This paper comprehensively addresses the recent work on the design and optimization of metal oxide ReRAM-based synaptic devices. A performance enhancement methodology and optimized operation scheme to achieve analog resistive switching and low-energy training behavior are provided. A three-dimensional vertical synapse network architecture is proposed for high-density integration and low-cost fabrication. The impacts of the ReRAM synaptic device features on the performances of neuromorphic systems are also discussed on the basis of a constructed neuromorphic visual system with a pattern recognition function. Possible solutions to achieve the high recognition accuracy and efficiency of neuromorphic systems are presented.

  18. A high-performance complementary inverter based on transition metal dichalcogenide field-effect transistors.

    Science.gov (United States)

    Cho, Ah-Jin; Park, Kee Chan; Kwon, Jang-Yeon

    2015-01-01

    For several years, graphene has been the focus of much attention due to its peculiar characteristics, and it is now considered to be a representative 2-dimensional (2D) material. Even though many research groups have studied on the graphene, its intrinsic nature of a zero band-gap, limits its use in practical applications, particularly in logic circuits. Recently, transition metal dichalcogenides (TMDs), which are another type of 2D material, have drawn attention due to the advantage of having a sizable band-gap and a high mobility. Here, we report on the design of a complementary inverter, one of the most basic logic elements, which is based on a MoS2 n-type transistor and a WSe2 p-type transistor. The advantages provided by the complementary metal-oxide-semiconductor (CMOS) configuration and the high-performance TMD channels allow us to fabricate a TMD complementary inverter that has a high-gain of 13.7. This work demonstrates the operation of the MoS2 n-FET and WSe2 p-FET on the same substrate, and the electrical performance of the CMOS inverter, which is based on a different driving current, is also measured.

  19. Anthracene-Based Lanthanide Metal-Organic Frameworks: Synthesis, Structure, Photoluminescence, and Radioluminescence Properties

    Directory of Open Access Journals (Sweden)

    Stephan R. Mathis

    2018-01-01

    Full Text Available Four anthracene-based lanthanide metal-organic framework structures (MOFs were synthesized from the combination of the lanthanide ions, Eu3+, Tb3+, Er3+, and Tm3+, with 9,10-anthracenedicarboxylic acid (H2ADC in dimethylformamide (DMF under hydrothermal conditions. The 3-D networks crystalize in the triclinic system with P-1 space group with the following compositions: (i {{[Ln2(ADC3(DMF4·DMF]}n, Ln = Eu (1 and Tb (2} and (ii {{[Ln2(ADC3(DMF2(OH22·2DMF·H2O]}n, Ln = Er (3 and Tm (4}. The metal centers exist in various coordination environments; nine coordinate in (i, while seven and eight coordinate in (ii. The deprotonated ligand, ADC, assumes multiple coordination modes, with its carboxylate functional groups severely twisted away from the plane of the anthracene moiety. The structures show ligand-based photoluminescence, which appears to be significantly quenched when compared with that of the parent H2ADC solid powder. Structure 2 is the least quenched and showed an average photoluminescence lifetime from bi-exponential decay of 0.3 ns. On exposure to ionizing radiation, the structures show radioluminescence spectral features that are consistent with the isolation of the ligand units in its 3-D network. The spectral features vary among the 3-D networks and appear to suggest that the latter undergo significant changes in their molecular and/or electronic structure in the presence of the ionizing radiation.

  20. Influence of alkali metal hydroxides on corrosion of Zr-base alloys

    International Nuclear Information System (INIS)

    Jeong, Yong Hwan

    1996-01-01

    The influence of group-1 alkali hydroxides on different Zr-based alloys have been carried out in static autoclaves at 350 deg C in pressurized water, conditioned in low(0.32 mmol), medium(4.3 mmol) and high(31.5 mmol) equimolar concentration of Li-, Na-, K-, Rb- and Cs-hydroxide. Two types of alloys have been investigated: Zr-Sn-(TRM, Transition metal) and Zr-Sn-Nb-(TRM, Transition metal). From the experiments the cation could be identified as the responsible species for corrosion of Zr alloy in alkalized water. The radius of the cation governs the accelerated corrosion in the pre-transition region of Zr alloy. Incorporation of alkali cation into the zirconium oxide lattice is probably the mechanism which allows the corrosion enhancement for Li and Na and the significant lower effect for the other bases. Nb containing alloys showed lower corrosion resistance than Zr-Sn-TRM alloys in all alkali solutions. Both types of alloys were corroded significantly more in LiOH and NaOH than in the other alkali environments. Lowest corrosive aggressiveness has been found for CsOH followed by KOH. Concluding from the corrosion behavior in the different alkali environments and taking into account the tendency to accelerate the corrosion of Zr alloys, CsOH and KOH are possible alternate alkali for PWR (Pressurized Water Reactor) application. (author)

  1. Knowledge based system and decision making methodologies in materials selection for aircraft cabin metallic structures

    Science.gov (United States)

    Adhikari, Pashupati Raj

    Materials selection processes have been the most important aspects in product design and development. Knowledge-based system (KBS) and some of the methodologies used in the materials selection for the design of aircraft cabin metallic structures are discussed. Overall aircraft weight reduction means substantially less fuel consumption. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures inside the cabin. Among various methodologies of materials selection using Multi Criterion Decision Making (MCDM) techniques, a few of them are demonstrated with examples and the results are compared with those obtained using Ashby's approach in materials selection. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes in the process. Aluminum alloys with high strength-to-weight ratio have been second-to-none in most of the aircraft parts manufacturing. Magnesium alloys that are much lighter in weight as alternatives to the Al-alloys currently in use in the structures are tested using the methodologies and ranked results are compared. Each material attribute considered in the design are categorized as benefit and non-benefit attribute. Using Ashby's approach, material indices that are required to be maximized for an optimum performance are determined, and materials are ranked based on the average of consolidated indices ranking. Ranking results are compared for any disparity among the methodologies.

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

    Science.gov (United States)

    Mudunkotuwa, Imali Ama

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

  3. Metal-organic and supramolecular architectures based on mechanically interlocked molecules

    Science.gov (United States)

    Fernando, Isurika Rosini

    The focus of this work is on mechanically interlocked molecules (MIMs), which have unusual physicochemical and mechanical properties with potential applications in nano-scale/molecular devices and high strength materials. Rotaxanes, for example, consist of an axle-like molecule threaded through a wheel-like molecule, with bulky groups at the two ends of the axle preventing the wheel from dissociating. The position of the wheel along the axle can be switched in a controllable and reversible manner by applying external stimuli, a feature that might lead to the next generation of computers. Molecularly woven materials (MWMs), another example of molecules with mechanically interlocked features, are predicted to be unprecedentedly strong while being lightweight and flexible. With the ultimate goal of achieving control over the functioning of molecular devices in the solid state, a variety of pseudorotaxane building blocks were prepared and characterized, including a novel, rare blue-colored motif. The temperature-dependent assembly/disassembly of pseudorotaxanes was exploited for the construction of single-wavelength colorimetric temperature sensors over a 100 °C window. Pseudorotaxanes based on aromatic crown ether wheels and disubstituted 4,4'-bipyridinium axles were converted into rotaxanes upon binding to metal complexes (zinc, cadmium, mercury, copper, cobalt), and the formation of ordered crystalline arrays was studied in the solid state. The columnar organization of pseudorotaxanes by Hg2X6 2-- complexes (X = Cl, Br, I), leading to unprecedented dichroic (blue/red) rotaxane crystals, was demonstrated for the first time. From the crystal structures studied it became apparent that negatively charged metal complexes are needed for successful assembly with the positively charged pseudorotaxane units. To be able to use the more common, positively charged metal ions for rotaxane framework construction, neutral and negatively charged pseudorotaxanes were synthesized

  4. Remote stabilization of copper paddlewheel based molecular building blocks in metal-organic frameworks

    KAUST Repository

    Gao, Wenyang

    2015-03-24

    Copper paddlewheel based molecular building blocks (MBBs) are ubiquitous and have been widely employed for the construction of highly porous metal-organic frameworks (MOFs). However, most copper paddlewheel based MOFs fail to retain their structural integrity in the presence of water. This instability is directly correlated to the plausible displacement of coordinating carboxylates in the copper paddlewheel MBB, [Cu2(O2C-)4], by the strongly coordinating water molecules. In this comprehensive study, we illustrate the chemical stability control in the rht-MOF platform via strengthening the coordinating bonds within the triangular inorganic MBB, [Cu3O(N4-x(CH)xC-)3] (x = 0, 1, or 2). Remotely, the chemical stabilization propagated into the paddlewheel MBB to afford isoreticular rht-MOFs with remarkably enhanced water/chemical stabilities compared to the prototypal rht-MOF-1. © 2015 American Chemical Society.

  5. Metal-oxide based nanoobjects: reactivity, building blocks for polymeric structures and structural variety

    International Nuclear Information System (INIS)

    Mueller, A.; Roy, S.

    2002-01-01

    The latest achievements in the new field of nanochemistry, i.e. investigation of reactions proceeding at selected sites of well-characterized metal-oxide based nanoobjects are reviewed. It is demonstrated that from the unique library of molybdenum-oxide based building blocks/fragments under reducing conditions in aqueous solution a huge variety of nanoobjects can be generated. Examples include the well-known molecular big-wheel of the type { Mo 176 } and big-ball of the type { Mo 132 } including their derivatives which are considered here. In addition, the by far largest structurally well-characterized cluster having 368 molybdenum atoms with the shape of a lemon is outlines and discussed [ru

  6. Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

    Directory of Open Access Journals (Sweden)

    Yongsheng Wang

    2014-04-01

    Full Text Available The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass–matrix composite (MGMC were investigated by using an in-situ tensile test under transmission electron microscopy (TEM. It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.

  7. Investigation on the tensile behavior of fiber metal laminates based on self-reinforced polypropylene

    Science.gov (United States)

    Lee, Byoung-Eon; Park, Tom; Kim, Jeong; Kang, Beom-Soo; Song, Woo-Jin

    2013-12-01

    Mechanical tests have been carried out to accurately evaluate the tensile properties of fiber metal laminates (FMLs). The FMLs in this paper comprised of a layer of self-reinforced polypropylene (SRPP) sandwiched between two layers of aluminum alloy 5052-H34. In this study, nonlinear tensile and fracture behavior of FMLs under the in-plane loading conditions has been investigated with numerical simulations and theoretical analysis. The numerical simulation based on finite element modeling using the ABAQUS/Explicit and the theoretical constitutive model based on a volume fraction approach and a modified classical lamination theory, which incorporates the elastic-plastic behavior of the aluminum alloy are used to predict the mechanical properties such as stress-strain response and deformation behavior of FMLs. In addition, through comparing the numerical simulations and the theoretical analysis with experimental results, it was concluded that a numerical simulation model adopted describes with sufficient accuracy the overall tensile stress-strain curve.

  8. Influence of air and vacuum environment on fatigue behavior of Zr-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Wang, G.Y.; Liaw, P.K.; Yokoyama, Y.; Peter, W.H.; Yang, B.; Freels, M.; Buchanan, R.A.; Liu, C.T.; Brooks, C.R.

    2007-01-01

    High-cycle fatigue (HCF) experiments in air and vacuum at room temperature were conducted on zirconium (Zr)-based bulk-metallic glasses (BMGs): Zr 50 Cu 40 Al 10 , Zr 50 Cu 30 Al 10 Ni 10 , and Zr 50 Cu 37 Al 10 Pd 3 in atomic percent. The fatigue-endurance limit of Zr 50 Cu 37 Al 10 Pd 3 was found to be significantly greater than those of Zr 50 Cu 40 Al 10 and Zr 50 Cu 30 Al 10 Ni 10 , which indicates that the inclusions of Pd and the resulting nano structures improve the fatigue resistances of the Zr-based BMGs. The fatigue lives in vacuum and air were generally found to be comparable

  9. Spatially correlated two-dimensional arrays of semiconductor and metal quantum dots in GaAs-based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nevedomskiy, V. N., E-mail: nevedom@mail.ioffe.ru; Bert, N. A.; Chaldyshev, V. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Preobrazhernskiy, V. V.; Putyato, M. A.; Semyagin, B. R. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2015-12-15

    A single molecular-beam epitaxy process is used to produce GaAs-based heterostructures containing two-dimensional arrays of InAs semiconductor quantum dots and AsSb metal quantum dots. The twodimensional array of AsSb metal quantum dots is formed by low-temperature epitaxy which provides a large excess of arsenic in the epitaxial GaAs layer. During the growth of subsequent layers at a higher temperature, excess arsenic forms nanoinclusions, i.e., metal quantum dots in the GaAs matrix. The two-dimensional array of such metal quantum dots is created by the δ doping of a low-temperature GaAs layer with antimony which serves as a precursor for the heterogeneous nucleation of metal quantum dots and accumulates in them with the formation of AsSb metal alloy. The two-dimensional array of InAs semiconductor quantum dots is formed via the Stranski–Krastanov mechanism at the GaAs surface. Between the arrays of metal and semiconductor quantum dots, a 3-nm-thick AlAs barrier layer is grown. The total spacing between the arrays of metal and semiconductor quantum dots is 10 nm. Electron microscopy of the structure shows that the arrangement of metal quantum dots and semiconductor quantum dots in the two-dimensional arrays is spatially correlated. The spatial correlation is apparently caused by elastic strain and stress fields produced by both AsSb metal and InAs semiconductor quantum dots in the GaAs matrix.

  10. Spatially correlated two-dimensional arrays of semiconductor and metal quantum dots in GaAs-based heterostructures

    International Nuclear Information System (INIS)

    Nevedomskiy, V. N.; Bert, N. A.; Chaldyshev, V. V.; Preobrazhernskiy, V. V.; Putyato, M. A.; Semyagin, B. R.

    2015-01-01

    A single molecular-beam epitaxy process is used to produce GaAs-based heterostructures containing two-dimensional arrays of InAs semiconductor quantum dots and AsSb metal quantum dots. The twodimensional array of AsSb metal quantum dots is formed by low-temperature epitaxy which provides a large excess of arsenic in the epitaxial GaAs layer. During the growth of subsequent layers at a higher temperature, excess arsenic forms nanoinclusions, i.e., metal quantum dots in the GaAs matrix. The two-dimensional array of such metal quantum dots is created by the δ doping of a low-temperature GaAs layer with antimony which serves as a precursor for the heterogeneous nucleation of metal quantum dots and accumulates in them with the formation of AsSb metal alloy. The two-dimensional array of InAs semiconductor quantum dots is formed via the Stranski–Krastanov mechanism at the GaAs surface. Between the arrays of metal and semiconductor quantum dots, a 3-nm-thick AlAs barrier layer is grown. The total spacing between the arrays of metal and semiconductor quantum dots is 10 nm. Electron microscopy of the structure shows that the arrangement of metal quantum dots and semiconductor quantum dots in the two-dimensional arrays is spatially correlated. The spatial correlation is apparently caused by elastic strain and stress fields produced by both AsSb metal and InAs semiconductor quantum dots in the GaAs matrix

  11. The determination, by x-ray-fluorescence spectrometry, of noble and base metals in matte-leach residues

    International Nuclear Information System (INIS)

    Austen, C.E.

    1977-01-01

    An accurate and precise method is described for the determination of noble and base metals in matte-leach residues. Preparation of the samples essentially involves fusion with sodium peroxide in a zirconium crucible and leaching with hydrochloric and nitric acids. Matrix correction and calibration are achieved by use of the single-standard calibration method with reference solutions prepared from pure metals or from compounds of the element to be determined

  12. A luminescent lanthanide coordination polymer based on energy transfer from metal to metal for hydrogen peroxide detection.

    Science.gov (United States)

    Zeng, Hui-Hui; Zhang, Li; Rong, Lian-Qing; Liang, Ru-Ping; Qiu, Jian-Ding

    2017-03-15

    A bimetal lanthanide coordination polymer nanoparticle (ATP-Ce/Tb-Tris CPNs) with good biocompatibility was synthesized in Tris-HCl buffer using adenosine triphosphate (ATP) molecules as the bridge ligands. The large absorption cross section and suitable emission energy of Ce 3+ matching to the adsorption energy of Tb 3+ ( 4 f n ) results in the efficient energy transfer from Ce 3+ to Tb 3+ , thus the synthesized ATP-Ce/Tb-Tris CPNs exhibit the characteristic green emission of Tb 3+ . Such energy transfer from metal to metal in fluorescent lanthanide coordination polymer nanoparticles (Ln-CPNs) has been demonstrated. It is found that the oxidation of Ce 3+ in ATP-Ce/Tb-Tris CNPs to Ce 4+ would interrupt the energy transfer from Ce 3+ to Tb 3+ , leading to fluorescence quenching of Tb 3+ . On the basis of this quenching mechanism, ATP-Ce/Tb-Tris CPNs has been successfully used to detect reactive oxygen H 2 O 2 with detection limit as low as 2nM. If glucose oxidase is present in the system, glucose can be determined using the ATP-Ce/Tb-Tris CNPs nanosensor. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Spurious structures created by interpolation-based CT metal artifact reduction

    Science.gov (United States)

    Müller, J.; Buzug, T. M.

    2009-02-01

    Under normal circumstances the quality of images reconstructed with the classic FBP CT reconstruction algorithm is adequate for medical diagnosis. However, in some special cases the assumptions made by this method are not applicable because of non-linearities in the underlying physical imaging processes. Especially in the presence of metal implants in the field of view, effects like beam hardening, scatter and photon starvation result in serious streaking and banding artifacts around and between these objects. In order to reduce the artifacts, several different types of correction methods were introduced during the last two decades. In one of the most often used approaches, an interpolation scheme is used to replace all corrupted beam data in the shadow of the metal with artificially generated values. Although this leads to a reduction of the most severe artifacts, typically the results are far from being perfect. Instead of removing all artifacts, in most cases new streak artifacts are introduced. In the present work it is shown that the origin of these new artifacts is related to the loss of edge information of the objects by using surrogate data. The application of a more sophisticated artifact reduction method based on a segmentation of a preliminary reconstructed image decreases the number of newly introduced artifacts to a large degree. This is possible, because edge information between air and tissue recovered from the preliminary reconstruction can be included into the correction scheme. It is concluded that a restoration scheme without additionally information is not sufficient for a successful metal artifact reduction method.

  14. Training and operation of an integrated neuromorphic network based on metal-oxide memristors

    Science.gov (United States)

    Prezioso, M.; Merrikh-Bayat, F.; Hoskins, B. D.; Adam, G. C.; Likharev, K. K.; Strukov, D. B.

    2015-05-01

    Despite much progress in semiconductor integrated circuit technology, the extreme complexity of the human cerebral cortex, with its approximately 1014 synapses, makes the hardware implementation of neuromorphic networks with a comparable number of devices exceptionally challenging. To provide comparable complexity while operating much faster and with manageable power dissipation, networks based on circuits combining complementary metal-oxide-semiconductors (CMOSs) and adjustable two-terminal resistive devices (memristors) have been developed. In such circuits, the usual CMOS stack is augmented with one or several crossbar layers, with memristors at each crosspoint. There have recently been notable improvements in the fabrication of such memristive crossbars and their integration with CMOS circuits, including first demonstrations of their vertical integration. Separately, discrete memristors have been used as artificial synapses in neuromorphic networks. Very recently, such experiments have been extended to crossbar arrays of phase-change memristive devices. The adjustment of such devices, however, requires an additional transistor at each crosspoint, and hence these devices are much harder to scale than metal-oxide memristors, whose nonlinear current-voltage curves enable transistor-free operation. Here we report the experimental implementation of transistor-free metal-oxide memristor crossbars, with device variability sufficiently low to allow operation of integrated neural networks, in a simple network: a single-layer perceptron (an algorithm for linear classification). The network can be taught in situ using a coarse-grain variety of the delta rule algorithm to perform the perfect classification of 3 × 3-pixel black/white images into three classes (representing letters). This demonstration is an important step towards much larger and more complex memristive neuromorphic networks.

  15. Bond strength of resin cements to noble and base metal alloys with different surface treatments.

    Directory of Open Access Journals (Sweden)

    Farkhondeh Raeisosadat

    2014-10-01

    Full Text Available The bond strength of resin cements to metal alloys depends on the type of the metal, conditioning methods and the adhesive resins used. The purpose of this study was to evaluate the bond strength of resin cements to base and noble metal alloys after sand blasting or application of silano-pen.Cylinders of light cured Z 250 composite were cemented to "Degubond 4" (Au Pd and "Verabond" (Ni Cr alloys by either RelyX Unicem or Panavia F2, after sandblasting or treating the alloys with Silano-Pen. The shear bond strengths were evaluated. Data were analyzed by three-way ANOVA and t tests at a significance level of P<0.05.When the alloys were treated by Silano-Pen, RelyX Unicem showed a higher bond strength for Degubond 4 (P=0.021 and Verabond (P< 0.001. No significant difference was observed in the bond strength of Panavia F2 to the alloys after either of surface treatments, Degubond 4 (P=0.291 and Verabond (P=0.899. Panavia F2 showed a higher bond strength to sandblasted Verabond compared to RelyX Unicem (P=0.003. The bond strength of RelyX Unicem was significantly higher to Silano-Pen treated Verabond (P=0.011. The bond strength of the cements to sandblasted Degubond 4 showed no significant difference (P=0.59. RelyX Unicem had a higher bond strength to Silano-Pen treated Degubond 4 (P=0.035.The bond strength of resin cements to Verabond alloy was significantly higher than Degubond 4. RelyX Unicem had a higher bond strength to Silano-Pen treated alloys. Surface treatments of the alloys did not affect the bond strength of Panavia F2.

  16. Enhanced vasculotoxic metal excretion in post-myocardial infarction patients following a single edetate disodium-based infusion.

    Science.gov (United States)

    Arenas, Ivan A; Navas-Acien, Ana; Ergui, Ian; Lamas, Gervasio A

    2017-10-01

    Toxic metals have been associated with cardiovascular mortality and morbidity. We have hypothesized that enhanced excretion of vasculotoxic metals might explain the positive results of the Trial to Assess Chelation Therapy (TACT). The purpose of this study was to determine whether a single infusion of the edetate disodium- based infusion used in TACT led to enhanced excretion of toxic metals known to be associated with cardiovascular events. Twenty six patients (post-MI, age > 50 years, serum creatinine ≤ 2.0mg/dL) were enrolled in this open-label study. Urinary levels of 20 toxic metals normalized to urinary creatinine concentrations were measured at baseline in overnight urine collections, for 6h following a placebo infusion of 500mL normal saline and 1.2% dextrose, and for 6h following a 3g edetate disodium-based infusion. Self-reported metal exposure, smoking status, food frequency, occupational history, drinking water source, housing and hobbies were collected at baseline by a metal exposure questionnaire. The mean age was 65 years (range 51-81 years). All patients were male. 50% had diabetes mellitus and 58% were former smokers. Mean (SD) serum creatinine was 0.95 (0.31) mg/dL. Toxic metals were detected in the baseline urine of >80% of patients. After placebo infusion there were no significant changes in total urinary metal levels. After edetate infusion, total urinary metal level increased by 71% compared to baseline (1500 vs. 2580µg/g creatinine; Pmetals with established epidemiologic evidence and mechanisms linking them to coronary and vascular events. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Automatic BSS-based filtering of metallic interference in MEG recordings: definition and validation using simulated signals

    Science.gov (United States)

    Migliorelli, Carolina; Alonso, Joan F.; Romero, Sergio; Mañanas, Miguel A.; Nowak, Rafał; Russi, Antonio

    2015-08-01

    Objective. One of the principal drawbacks of magnetoencephalography (MEG) is its high sensitivity to metallic artifacts, which come from implanted intracranial electrodes and dental ferromagnetic prosthesis and produce a high distortion that masks cerebral activity. The aim of this study was to develop an automatic algorithm based on blind source separation (BSS) techniques to remove metallic artifacts from MEG signals. Approach. Three methods were evaluated: AMUSE, a second-order technique; and INFOMAX and FastICA, both based on high-order statistics. Simulated signals consisting of real artifact-free data mixed with real metallic artifacts were generated to objectively evaluate the effectiveness of BSS and the subsequent interference reduction. A completely automatic detection of metallic-related components was proposed, exploiting the known characteristics of the metallic interference: regularity and low frequency content. Main results. The automatic procedure was applied to the simulated datasets and the three methods exhibited different performances. Results indicated that AMUSE preserved and consequently recovered more brain activity than INFOMAX and FastICA. Normalized mean squared error for AMUSE decomposition remained below 2%, allowing an effective removal of artifactual components. Significance. To date, the performance of automatic artifact reduction has not been evaluated in MEG recordings. The proposed methodology is based on an automatic algorithm that provides an effective interference removal. This approach can be applied to any MEG dataset affected by metallic artifacts as a processing step, allowing further analysis of unusable or poor quality data.

  18. Fe(III)-based metal-organic framework-derived core-shell nanostructure: Sensitive electrochemical platform for high trace determination of heavy metal ions.

    Science.gov (United States)

    Zhang, Zhihong; Ji, Hongfei; Song, Yingpan; Zhang, Shuai; Wang, Minghua; Jia, Changchang; Tian, Jia-Yue; He, Linghao; Zhang, Xiaojing; Liu, Chun-Sen

    2017-08-15

    A new core-shell nanostructured composite composed of Fe(III)-based metal-organic framework (Fe-MOF) and mesoporous Fe 3 O 4 @C nanocapsules (denoted as Fe-MOF@mFe 3 O 4 @mC) was synthesized and developed as a platform for determining trace heavy metal ions in aqueous solution. Herein, the mFe 3 O 4 @mC nanocapsules were prepared by calcining the hollow Fe 3 O 4 @C that was obtained using the SiO 2 nanoparticles as the template, followed by composing the Fe-MOF. The Fe-MOF@mFe 3 O 4 @mC nanocomposite demonstrated excellent electrochemical activity, water stability and high specific surface area, consequently resulting in the strong biobinding with heavy-metal-ion-targeted aptamer strands. Furthermore, by combining the conformational transition interaction, which is caused by the formation of the G-quadruplex between a single-stranded aptamer and high adsorbed amounts of heavy metal ions, the developed aptasensor exhibited a good linear relationship with the logarithm of heavy metal ion (Pb 2+ and As 3+ ) concentration over the broad range from 0.01 to 10.0nM. The detection limits were estimated to be 2.27 and 6.73 pM toward detecting Pb 2+ and As 3+ , respectively. The proposed aptasensor showed good regenerability, excellent selectivity, and acceptable reproducibility, suggesting promising applications in environment monitoring and biomedical fields. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Raman spectroscopy of metal/organic/inorganic heterostructures and pentacene-based OFETs

    Energy Technology Data Exchange (ETDEWEB)

    Paez-Sierra, Beynor Antonio

    2007-12-20

    In the framework of this thesis the interaction of In and Mg as top electrodes on two perylene derivates, 3,4,9,10-perylene tetracarbonic acid dianhydride (PTCDA) and dimethyl-3,4,9,10-perylene tetracarbonic acid diimide (DiMe-PTCDI) was studied. The metal-organic layers wer fabricated on S-passivated GaAs(100)2 x 1 substrates. As main characterization method the Raman spectroscopy was applied. The PTCDA/Mg form themselves by two stages of the metal growth, the first belongs to a new molecular structure for a Mg layer thinner than 2.8 nm, whereby the PTCA molecule loses the oxygen atom from the dianhydride group. The second belongs to the surface-amplified Raman spectrum of the preceding structure. In the case of the Mg/DiMe-PTCDI heterostructures the molecule is well conserved, whereby the Raman shift on the diimide group is not modified. Also this structure shows a coupling between discrete molecule eigenvibrations of 221 cm{sup -1}, 1291 cm{sup -1}, and 1606 cm{sup -1} of the organic material and the electronic continuum states of the Mg metal contact. The studies on the preceding heterostructures helped to analyze experimentally the channel formation of pentacene-based organic field-effect transistors. [German] Im Rahmen dieser Arbeit wurden die Wechselwirkung von In und Mg als Topelektroden auf zwei Perylen-Derivativen, 3,4,9,10-Perylentetracarbonsaure Dianhydrid (PTCDA) und Dimethyl-3,4,9,10- Perylentetracarbonsaure Diimid (DiMe-PTCDI) untersucht. Die Metal/organische Schichten wurden auf S-passivierten GaAs(100):2 x 1-Substraten hergestellt. Als Hauptcharakterisierungsmethode wird die Raman-Spektroskopie eingesetzt. Die PTCDA/Mg Strukturen formen sich durch zwei Stufen des Metallwachstum, die erste gehoert zu einer neuen molekularen Struktur fuer eine Mg Schicht duenner als 2.8 nm, wobei das PTCA-Molekuel das Sauerstoffatom von der Dianhydridgruppe verliert. Die zweite gehoert zu dem oberflaechenverstaerkten Ramanspektrum von der vorherigen Struktur. Im

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

    Science.gov (United States)

    Murahashi, Shun-Ichi

    2011-01-01

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

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

    Science.gov (United States)

    MURAHASHI, Shun-Ichi

    2011-01-01

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

  2. Metal Artifact Reduction in Dental Computed Tomography Images Based on Sinogram Segmentation Using Curvelet Transform Followed by Hough Transform.

    Science.gov (United States)

    Yazdi, Mehran; Mohammadi, Maryam

    2017-01-01

    In X-ray computed tomography (CT), the presence of metal objects in a patient's body produces streak artifacts in the reconstructed images. During the past decades, many different methods were proposed for the reduction or elimination of the streaking artifacts. When scanning a patient, the projection data affected by metal objects (missing projections) appear as regions with high intensities in the sinogram. In spiral fan beam CT, these regions are sinusoid-like curves on sinogram. During the first time, if the metal curves are detected carefully, then, they can be replaced by corresponding unaffected projections using other slices or opposite views; therefore, the CT slices regenerated by the modified sonogram will be imaged with high quality. In this paper, a new method of the segmentation of metal traces in spiral fan-beam CT sinogram is proposed. This method is based on a sinogram curve detection using a curvelet transform followed by 2D Hough transform. The initial enhancement of the sinogram using modified curvelet transform coefficients is performed by suppressing all the coefficients of one band and applying 2D Hough transform to detect more precisely metal curves. To evaluate the performance of the proposed method for the detection of metal curves in a sinogram, precision and recall metrics are calculated. Compared with other methods, the results show that the proposed method is capable of detecting metal curves, with better precision and good recovery.

  3. Ice-core based assessment of historical anthropogenic heavy metal (Cd, Cu, Sb, Zn) emissions in the Soviet Union.

    Science.gov (United States)

    Eichler, Anja; Tobler, Leonhard; Eyrikh, Stella; Malygina, Natalia; Papina, Tatyana; Schwikowski, Margit

    2014-01-01

    The development of strategies and policies aiming at the reduction of environmental exposure to air pollution requires the assessment of historical emissions. Although anthropogenic emissions from the extended territory of the Soviet Union (SU) considerably influenced concentrations of heavy metals in the Northern Hemisphere, Pb is the only metal with long-term historical emission estimates for this region available, whereas for selected other metals only single values exist. Here we present the first study assessing long-term Cd, Cu, Sb, and Zn emissions in the SU during the period 1935-1991 based on ice-core concentration records from Belukha glacier in the Siberian Altai and emission data from 12 regions in the SU for the year 1980. We show that Zn primarily emitted from the Zn production in Ust-Kamenogorsk (East Kazakhstan) dominated the SU heavy metal emission. Cd, Sb, Zn (Cu) emissions increased between 1935 and the 1970s (1980s) due to expanded non-ferrous metal production. Emissions of the four metals in the beginning of the 1990s were as low as in the 1950s, which we attribute to the economic downturn in industry, changes in technology for an increasing metal recovery from ores, the replacement of coal and oil by gas, and air pollution control.

  4. A dipeptide-based superhydrogel: Removal of toxic dyes and heavy metal ions from waste water.

    Science.gov (United States)

    Nandi, Nibedita; Baral, Abhishek; Basu, Kingshuk; Roy, Subhasish; Banerjee, Arindam

    2017-01-01

    A short peptide-based molecule has been found to form a strong hydrogel at phosphate buffer solution of pH 7.46. The hydrogel has been characterized thoroughly using various techniques including field emission scanning electron microscopy (FE-SEM), wide angle powder X-ray diffraction (PXRD), and rheological analysis. It has been observed from FE-SEM images that entangled nanofiber network is responsible for gelation. Rheological investigation demonstrates that the self-assembly of this synthetic dipeptide results in the formation of mechanically strong hydrogel with storage modulus (G') around 10 4 Pa. This gel has been used for removing both cationic and anionic toxic organic dyes (Brilliant Blue, Congo red, Malachite Green, Rhodamine B) and metal ions (Co 2+ and Ni 2+ ) from waste water. Moreover, only a small amount of the gelator is required (less than 1 mg/mL) for preparation of this superhydrogel and even this hydrogel can be reused three times for dye/metal ion absorption. This signifies the importance of the hydrogel towards waste water management. © 2016 Wiley Periodicals, Inc.

  5. Nanoparticle-based immunosensor with apoferritin templated metallic phosphate label for quantification of phosphorylated acetylcholinesterase

    Energy Technology Data Exchange (ETDEWEB)

    Du, Dan; Chen, Aiqiong; Xie, Yunying; Zhang, Aidong; Lin, Yuehe

    2011-05-15

    A new sandwich-like electrochemical immunosensor has been developed for quantification of organophosphorylated acetylcholinesterase (OP-AChE), an exposure biomarker of organophosphate pesticides and nerve agents. Zirconia nanoparticles (ZrO2 NPs) were anchored on a screen printed electrode (SPE) to preferably capture OP-AChE adducts by metal chelation with phospho-moieties, which was selectively recognized by lead phosphate-apoferritin labeled anti-AChE antibody (LPA-anti-AChE). The sandwich-like immunoreactions were performed among ZrO2 NPs, OP-AChE and LPA-anti-AChE to form ZrO2/OP-AChE/LPA-anti-AChE complex and the released lead ions were detected on a disposable SPE. The binding affinity was investigated by both square wave voltammetry (SWV) and quartz crystal microbalance (QCM) measurements. The proposed immunosensor yielded a linear response current over a broad OP-AChE concentrations range from 0.05 nM to 10 nM, with detection limit of 0.02 nM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This method avoids the drawback of unavailability of commercial OP-specific antibody as well as amplifies detection signal by using apoferritin encoded metallic phosphate nanoparticle tags. This nanoparticle-based immunosensor offers a new method for rapid, sensitive, selective and inexpensive quantification of phosphorylated adducts for monitoring of OP pesticides and nerve agents exposures.

  6. Mechanically durable underwater superoleophobic surfaces based on hydrophilic bulk metals for oil/water separation

    Science.gov (United States)

    Yu, Huadong; Lian, Zhongxu; Xu, Jinkai; Wan, Yanling; Wang, Zuobin; Li, Yiquan; Yu, Zhanjiang; Weng, Zhankun

    2018-04-01

    Despite the success of previous methods for fabricating underwater superoleophobic surfaces, most of the surfaces based on soft materials are prone to collapse and deformation due to their mechanically fragile nature, and they fail to perform their designed functions after the surface materials are damaged in water. In this work, the nanosecond laser-induced oxide coatings on hydrophilic bulk metals are reported which overcomes the limitation and shows the robust underwater superoleophobicity to a mechanical challenge encountered by surfaces deployed in water environment. The results show that the surface materials have the advantage that the underwater superoleophobicity is still preserved after the surfaces are scratched by knife or sandpaper and even completely destroyed because of the hydrophilic property of damaged materials in water. It is important that the results provide a guide for the design of durable underwater superoleophobic surfaces, and the development of superoleophobic materials in many potential applications such as the oil-repellent and the oil/water separation. Additionally, the nanosecond laser technology is simple, cost-effective and suitable for the large-area and mass fabrication of mechanically durable underwater superoleophobic metal materials.

  7. Nanoporous Hybrid Electrolytes for High-Energy Batteries Based on Reactive Metal Anodes

    KAUST Repository

    Tu, Zhengyuan

    2017-01-06

    Successful strategies for stabilizing electrodeposition of reactive metals, including lithium, sodium, and aluminum are a requirement for safe, high-energy electrochemical storage technologies that utilize these metals as anodes. Unstable deposition produces high-surface area dendritic structures at the anode/electrolyte interface, which causes premature cell failure by complex physical and chemical processes that have presented formidable barriers to progress. Here, it is reported that hybrid electrolytes created by infusing conventional liquid electrolytes into nanoporous membranes provide exceptional ability to stabilize Li. Electrochemical cells based on γ-Al2O3 ceramics with pore diameters below a cut-off value above 200 nm exhibit long-term stability even at a current density of 3 mA cm−2. The effect is not limited to ceramics; similar large enhancements in stability are observed for polypropylene membranes with less monodisperse pores below 450 nm. These findings are critically assessed using theories for ion rectification and electrodeposition reactions in porous solids and show that the source of stable electrodeposition in nanoporous electrolytes is fundamental.

  8. Role of nanorods insertion layer in ZnO-based electrochemical metallization memory cell

    Science.gov (United States)

    Mangasa Simanjuntak, Firman; Singh, Pragya; Chandrasekaran, Sridhar; Juanda Lumbantoruan, Franky; Yang, Chih-Chieh; Huang, Chu-Jie; Lin, Chun-Chieh; Tseng, Tseung-Yuen

    2017-12-01

    An engineering nanorod array in a ZnO-based electrochemical metallization device for nonvolatile memory applications was investigated. A hydrothermally synthesized nanorod layer was inserted into a Cu/ZnO/ITO device structure. Another device was fabricated without nanorods for comparison, and this device demonstrated a diode-like behavior with no switching behavior at a low current compliance (CC). The switching became clear only when the CC was increased to 75 mA. The insertion of a nanorods layer induced switching characteristics at a low operation current and improve the endurance and retention performances. The morphology of the nanorods may control the switching characteristics. A forming-free electrochemical metallization memory device having long switching cycles (>104 cycles) with a sufficient memory window (103 times) for data storage application, good switching stability and sufficient retention was successfully fabricated by adjusting the morphology and defect concentration of the inserted nanorod layer. The nanorod layer not only contributed to inducing resistive switching characteristics but also acted as both a switching layer and a cation diffusion control layer.

  9. Nanoarchitectures in dye-sensitized solar cells: metal oxides, oxide perovskites and carbon-based materials.

    Science.gov (United States)

    Shaikh, Jasmin S; Shaikh, Navajsharif S; Mali, Sawanta S; Patil, Jyoti V; Pawar, Krishna K; Kanjanaboos, Pongsakorn; Hong, Chang Kook; Kim, J H; Patil, Pramod S

    2018-03-15

    Dye-sensitized solar cells (DSSCs) have aroused great interest and been regarded as a potential renewable energy resource among the third-generation solar cell technologies to fulfill the 21 st century global energy demand. DSSCs have notable advantages such as low cost, easy fabrication process and being eco-friendly in nature. The progress of DSSCs over the last 20 years has been nearly constant due to some limitations, like poor long-term stability, narrow absorption spectrum, charge carrier transportation and collection losses and poor charge transfer mechanism for regeneration of dye molecules. The main challenge for the scientific community is to improve the performance of DSSCs by using different approaches, like finding new electrode materials with suitable nanoarchitectures, dyes in composition with promising semiconductors and metal quantum dot fluorescent dyes, and cost-effective hole transporting materials (HTMs). This review focuses on DSSC photo-physics, which includes charge separation, effective transportation, collection and recombination processes. Different nanostructured materials, including metal oxides, oxide perovskites and carbon-based composites, have been studied for photoanodes, and counter electrodes, which are crucial to achieve DSSC devices with higher efficiency and better stability.

  10. The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

    Full Text Available Effects of substitutions of rare earth (RE elements (Y, La, Ce, and Nd to the Zr-based AB2 multi-phase metal hydride (MH alloys on the structure, gaseous phase hydrogen storage (H-storage, and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15 are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation and is recommended for all the AB2 MH alloys for electrochemical applications.

  11. Nanoparticle-based immunosensor with apoferritin templated metallic phosphate label for quantification of phosphorylated acetylcholinesterase

    International Nuclear Information System (INIS)

    Du, Dan; Chen, Aiqiong; Xie, Yunying; Zhang, Aidong; Lin, Yuehe

    2011-01-01

    A new sandwich-like electrochemical immunosensor has been developed for quantification of organophosphorylated acetylcholinesterase (OP-AChE), an exposure biomarker of organophosphate pesticides and nerve agents. Zirconia nanoparticles (ZrO2 NPs) were anchored on a screen printed electrode (SPE) to preferably capture OP-AChE adducts by metal chelation with phospho-moieties, which was selectively recognized by lead phosphate-apoferritin labeled anti-AChE antibody (LPA-anti-AChE). The sandwich-like immunoreactions were performed among ZrO2 NPs, OP-AChE and LPA-anti-AChE to form ZrO2/OP-AChE/LPA-anti-AChE complex and the released lead ions were detected on a disposable SPE. The binding affinity was investigated by both square wave voltammetry (SWV) and quartz crystal microbalance (QCM) measurements. The proposed immunosensor yielded a linear response current over a broad OP-AChE concentrations range from 0.05 nM to 10 nM, with detection limit of 0.02 nM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This method avoids the drawback of unavailability of commercial OP-specific antibody as well as amplifies detection signal by using apoferritin encoded metallic phosphate nanoparticle tags. This nanoparticle-based immunosensor offers a new method for rapid, sensitive, selective and inexpensive quantification of phosphorylated adducts for monitoring of OP pesticides and nerve agents exposures.

  12. A novel Ni/ceria-based anode for metal-supported solid oxide fuel cells

    Science.gov (United States)

    Rojek-Wöckner, Veronika A.; Opitz, Alexander K.; Brandner, Marco; Mathé, Jörg; Bram, Martin

    2016-10-01

    For optimization of ageing behavior, electrochemical performance, and sulfur tolerance of metal-supported solid oxide fuel cells a new anode concept is introduced, which is based on a Ni/GDC cermet replacing the established Ni/YSZ anodes. In the present work optimized processing parameters compatible with MSC substrates are specified by doing sintering studies on pressed bulk specimen and on real porous anode structures. The electrochemical performance of the Ni/GDC anodes was characterized by means of symmetrical electrolyte supported model-type cells. In this study, three main objectives are pursued. Firstly, the effective technical realization of the Ni/GDC concept is demonstrated. Secondly, the electrochemical behavior of Ni/GDC porous anodes is characterized by impedance spectroscopy and compared with the current standard Ni/YSZ anode. Further, a qualitative comparison of the sulfur poisoning behavior of both anode types is presented. Thirdly, preliminary results of a successful implementation of the Ni/GDC cermet into a metal-supported single cell are presented.

  13. Microstructure Effects on Spall Strength of Titanium-based Bulk Metallic Glass Composites

    Science.gov (United States)

    Diaz, Rene; Hofmann, Douglas; Thadhani, Naresh; Georgia Tech Team; GT-JPL Collaboration

    2017-06-01

    The spall strength of Ti-based metallic glass composites is investigated as a function of varying volume fractions (0-80%) of in-situ formed crystalline dendrites. With increasing dendrite content, the topology changes such that neither the harder glass nor the softer dendrites dominate the microstructure. Plate-impact experiments were performed using the 80-mm single-stage gas gun over impact stresses up to 18 GPa. VISAR interferometry was used to obtain rear free-surface velocity profiles revealing the velocity pullback spall failure signals. The spall strengths were higher than for Ti-6Al-4V alloy, and remained high up to impact stress. The influence of microstructure on the spall strength is indicated by the constants of the power law fit with the decompression strain rate. Differences in fracture behavior reveal void nucleation as a dominant mechanism affecting the spall strength. The microstructure with neither 100% glass nor with very high crystalline content, provides the most tortuous path for fracture and therefore highest spall strength. The results allow projection of spall strength predictions for design of in-situ formed metallic glass composites. ARO Grant # W911NF-09 ``1-0403 NASA JPL Contract # 1492033 ``Prime # NNN12AA01C; NSF GRFP Grant #DGE-1148903; and NDSE & G.

  14. Metallic Langmuir and Langmuir-Blodgett films based on TTF derivatives and fatty acid

    International Nuclear Information System (INIS)

    Ohnuki, H.; Ishizaki, Y.; Suzuki, M.; Desbat, B.; Delhaes, P.; Giffard, M.; Imakubo, T.; Mabon, G.; Izumi, M.

    2002-01-01

    Recent progress in the metallic conducting Langmuir-Blodgett (LB) films built from TTF derivative and fatty acids is reported. A simple LB method of transferring the mixed Langmuir (L) film of BEDO-TTF (BO) and stearic acid (SA) onto substrates provided metallic conducting LB films. A homogeneous L film formation on the water surface observed by Brewster angle microscope (BAM) is an essential factor for the well-ordered LB films. In the L film, the carboxylate group of fatty acid forms anion layer bringing about a spontaneous formation of mixed valence state (MVS) of BO layer. Similar spontaneous formation was also found in the molecular combination of nonoxygen-substituted donor of EDT-TTF and octadecanesulfonic acid (OS). This type of reaction would be useful for obtaining conducting LB films. For the LB films of BEDO-TTF and stearic acid, we found a negative transverse magnetoresistance at low temperature that was interpreted in the weak localization of a two-dimensional (2D) electronic system based on the well-defined conducting layer

  15. Hot Embossing of Zr-Based Bulk Metallic Glass Micropart Using Stacked Silicon Dies

    Directory of Open Access Journals (Sweden)

    Zhijing Zhu

    2015-01-01

    Full Text Available We demonstrated hot embossing of Zr65Cu17.5Ni10Al7.5 bulk metallic glass micropart using stacked silicon dies. Finite element simulation was carried out, suggesting that it could reduce the stress below 400 MPa in the silicon dies and enhance the durability of the brittle silicon dies when using varying load mode (100 N for 60 s and then 400 N for 60 s compared with using constant load mode (200 N for 120 s. A micropart with good appearance was fabricated under the varying load, and no silicon die failure was observed, in agreement with the simulation. The amorphous state of the micropart was confirmed by differential scanning calorimeter and X-ray diffraction, and the nanohardness and Young’s modulus were validated close to those of the as-cast BMG rods by nanoindentation tests. The results proved that it was feasible to adopt the varying load mode to fabricate three-dimensional Zr-based bulk metallic glass microparts by hot embossing process.

  16. Surface Preparation and Deposited Gate Oxides for Gallium Nitride Based Metal Oxide Semiconductor Devices

    Science.gov (United States)

    Long, Rathnait D.; McIntyre, Paul C.

    2012-01-01

    The literature on polar Gallium Nitride (GaN) surfaces, surface treatments and gate dielectrics relevant to metal oxide semiconductor devices is reviewed. The significance of the GaN growth technique and growth parameters on the properties of GaN epilayers, the ability to modify GaN surface properties using in situ and ex situ processes and progress on the understanding and performance of GaN metal oxide semiconductor (MOS) devices are presented and discussed. Although a reasonably consistent picture is emerging from focused studies on issues covered in each of these topics, future research can achieve a better understanding of the critical oxide-semiconductor interface by probing the connections between these topics. The challenges in analyzing defect concentrations and energies in GaN MOS gate stacks are discussed. Promising gate dielectric deposition techniques such as atomic layer deposition, which is already accepted by the semiconductor industry for silicon CMOS device fabrication, coupled with more advanced physical and electrical characterization methods will likely accelerate the pace of learning required to develop future GaN-based MOS technology.

  17. Characterizing and modeling electrical response to light for metal-based EUV photoresists

    Science.gov (United States)

    Pret, Alessandro V.; Kocsis, Mike; De Simone, Danilo; Vandenberghe, Geert; Stowers, Jason; Giglia, Angelo; de Schepper, Peter; Mani, Antonio; Biafore, John J.

    2016-03-01

    Metal-based photoresists are appealing for use in EUV lithography due to their improved etch resistance and absorption compared with organic resists, and due to their resolving power demonstrated with 13.53 nm exposures using synchrotron light. Recently imec has started a new project to study novel photoresists for EUV lithography, with particular attention to metal containing materials, in order to explore alternative approaches that may offer superior characteristics in photoresist imaging and etching performance compared with more mature chemically amplified resists. In order to model these novel resists it is mandatory to understand both the optical properties and the electronic response to photon absorption. As in previous experiments on organic materials, some of the optical properties can be determined by merging analysis from high-energy electron scattering models (e.g. CXRO website), X-ray absorption spectroscopy, and DUV spectroscopic ellipsometry. Dispersion curves can be used to calculate the electronic inelastic and elastic mean-free paths; convolved with the expected spectrum at wafer level it is possible to estimate the electron yield and the secondary electron blur of the photoresist. These material properties can be used to modify the physical models currently used to simulate organic photoresist performance in computational lithography software.

  18. Alginate-based nanocomposites for efficient removal of heavy metal ions.

    Science.gov (United States)

    Esmat, Mohamed; Farghali, Ahmed A; Khedr, Mohamed H; El-Sherbiny, Ibrahim M

    2017-09-01

    Cobalt ferrite nanoparticles (CF), titanate nanotubes (T), alginate (G) and their nanocomposite microparticles (CF/G and T/G) were prepared and used for efficient removal of Cu 2+ , Fe 3+ and As 3+ ions from water. The nanocomposites were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), FTIR and vibrating sample magnetometer (VSM). In addition, the effects of pH, contact time, adsorbent weight and heavy metal ion concentration on the removal efficiency were investigated. Our results revealed a successful preparation of the nanocomposite particles. The optimized batch experiment conditions were found to be pH of 6.5, contact time of 2h and adsorbent weight of 0.15g. The removal efficiencies for Cu 2+ using G, CF, T, CF/G and T/G were found to be 91%, 100%, 99.9%, 95% and 98%, respectively. While that of Fe 3+ removal was 60%, 100%, 100%, 60% and 82%, respectively. Efficient removal of As 3+ ions was also attained (98% upon using T nanoadsorbents). The current study demonstrated that the developed nanomaterials (CF and T) and their corresponding alginate-based nanocomposite microparticles could be further tailored and used as efficient adsorbents for the uptake of different heavy metal ions from wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Modeling of stored charge in metallized biaxially oriented polypropylene film capacitors based on charging current measurement.

    Science.gov (United States)

    Li, Hua; Wang, Bowen; Li, Zhiwei; Liu, De; Lin, Fuchang; Dai, Ling; Zhang, Qin; Chen, Yaohong

    2013-10-01

    Metallized biaxially oriented polypropylene film (BOPP) capacitors are widely used in pulsed power systems. When the capacitor is used as the energy storage equipment under high electric field, more charges should be provided to maintain the voltage of the capacitor. This should be ascribed to the completion of the slow polarization which may take several hours or even longer. This paper focuses on the stored charge in metallized BOPP film capacitors. The modeling of the stored charge by the equivalent conversion of circuits is conducted to analyse the slow polarization in the BOPP film. The 3-RC network is proposed to represent the time-dependent charge stored in the capacitor. A charging current measurement system is established to investigate the charge storage property of the capacitor. The measurement system can measure the long time charging current with a sampling rate of 300 Hz. The total charge calculated by the charging current indicates that the stored charge in the capacitor under the electric field of 400 V/μm is 13.5% larger than the product of the voltage and the capacitance measured by the AC bridge. The nonlinear effect of the electric field on the slow polarization charge is also demonstrated. And the simulation of charge storage based on the 3-RC network can match well with the trend of the stored charge increasing with the time.

  20. Risk-Based Approach for Thermal Treatment of Soils Contaminated with Heavy Metals

    Directory of Open Access Journals (Sweden)

    Cocârţă D. M.

    2013-04-01

    Full Text Available In the actual context of limited soil resources and the significant degree of environmental pollution, public administrations and authorities are interested in restoring contaminated sites paying attention to the impact of these soils on human health. This paper aims to present the efficiency of the the incineration as a method for treatment of the contaminated soils t based on human health risk assessment. Through various experimentations, the following metals have been studied: Zn, Cu, Fe, Mn, Ni, Pb, Cr, Co, Cd, Hg, As and Be. The most important and interesting results concerning both thermal treatment removal efficiency and associated human health risk assessments were achieved concerning Cd, Pb and Ni contaminants. The behavior of Cadmium (Cd, Lead (Pb and Nickel (Ni concentrations from heavy metals incineration soil has been analyzed for three incineration temperatures (600°C, 800°C and 1000°C and two resident times of soil within the incineration reactor (30 min. and 60 min.. In this case, the level of contaminants in the treated soil can be reduced but not enough to ensure an acceptable risk for human health.

  1. A flexible ligand-based wavy layered metal-organic framework for lithium-ion storage.

    Science.gov (United States)

    An, Tiance; Wang, Yuhang; Tang, Jing; Wang, Yang; Zhang, Lijuan; Zheng, Gengfeng

    2015-05-01

    A substantial challenge for direct utilization of metal-organic frameworks (MOFs) as lithium-ion battery anodes is to maintain the rigid MOF structure during lithiation/delithiation cycles. In this work, we developed a flexible, wavy layered nickel-based MOF (C20H24Cl2N8Ni, designated as Ni-Me4bpz) by a solvothermal approach of 3,3',5,5'-tetramethyl-4,4'-bipyrazole (H2Me4bpz) with nickel(II) chloride hexahydrate. The obtained MOF materials (Ni-Me4bpz) with metal azolate coordination mode provide 2-dimensional layered structure for Li(+) intercalation/extraction, and the H2Me4bpz ligands allow for flexible rotation feature and structural stability. Lithium-ion battery anodes made of the Ni-Me4bpz material demonstrate excellent specific capacity and cycling performance, and the crystal structure is well preserved after the electrochemical tests, suggesting the potential of developing flexible layered MOFs for efficient and stable electrochemical storage. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Synthesis, Spectroscopic Characterization and Biological Activities of Transition Metal Complexes Derived from a Tridentate Schiff Base

    Directory of Open Access Journals (Sweden)

    J. Senthil Kumaran

    2013-01-01

    Full Text Available A new series of Cu (II, Ni (II, Co (II and Zn (II complexes have been synthesized from the Schiff base derived from 4-hydroxy-3-methoxybenzylidine-4-aminoantipyrine and 2-aminophenol. The structural features have been determined from their elemental analysis, magnetic susceptibility, molar conductance, Mass, IR, UV-Vis, 1H-NMR, 13C-NMR and ESR spectral studies. The redox behavior of the copper complex has been studied by cyclic voltammetry. The data confirm that the complexes have composition of ML2 type. The electronic absorption spectral data of the complexes propose an octahedral geometry around the central metal ion. All the metal complexes with DNA structure were guided by the presence of inter-molecular C–H⋯O and C–H⋯N hydrogen bonds. The biological activity of the synthesized compounds were tested against the bacterial species such as Bacillus subtilis, Staphylococcus aureus, Proteus vulgaris and fungal species such as Candida albicans by the well-diffusion method.

  3. Effect of base metal alloys recasting on marginal integrity of castable crowns.

    Science.gov (United States)

    Bajoghli, Farshad; Nosouhian, Saeid; Badrian, Hamid; Goroohi, Hossein; Saberian, Amir; Gadesi, Leyla

    2013-03-01

    Base metals have a wide use in casting methods. Sometimes they are reused in laboratories which may have an adverse effect on the restoration marginal integrity. This study aimed to investigate the effect of recasting of alloys on marginal integrity of restorations. Models with two types of finishing lines shoulder bevel 45° and shoulder 135° were produced and 15 wax copings were formed on each one of them. Each group containing 15 copings was divided into three subgroups A, B and C. Group A was casted with 100% new alloy, group B with 50% new and 50% recasted alloy and group C with 100% recasted alloy. Obtained metal copings were placed on dies and marginal gap size between restoration margin and the dies finishing line was measured using metric microscope and Moticam camera in four points, buccal, lingual, mesial and distal. A significant difference in mean marginal gap size exists among three types of alloys used (p-value = 0.036). A significant difference is observed between mean marginal gap size of two types of finishing lines for different alloys (p-value = 0.001). Using 100% recasted alloy is not recommended for any of the two types of finishing lines.

  4. Fatigue Life Prediction of Metallic Materials Based on the Combined Nonlinear Ultrasonic Parameter

    Science.gov (United States)

    Zhang, Yuhua; Li, Xinxin; Wu, Zhenyong; Huang, Zhenfeng; Mao, Hanling

    2017-08-01

    The fatigue life prediction of metallic materials is always a tough problem that needs to be solved in the mechanical engineering field because it is very important for the secure service of mechanical components. In this paper, a combined nonlinear ultrasonic parameter based on the collinear wave mixing technique is applied for fatigue life prediction of a metallic material. Sweep experiments are first conducted to explore the influence of driving frequency on the interaction of two driving signals and the fatigue damage of specimens, and the amplitudes of sidebands at the difference frequency and sum frequency are tracked when the driving frequency changes. Then, collinear wave mixing tests are carried out on a pair of cylindrically notched specimens with different fatigue damage to explore the relationship between the fatigue damage and the relative nonlinear parameters. The experimental results show when the fatigue degree is below 65% the relative nonlinear parameter increases quickly, and the growth rate is approximately 130%. If the fatigue degree is above 65%, the increase in the relative nonlinear parameter is slow, which has a close relationship with the microstructure evolution of specimens. A combined nonlinear ultrasonic parameter is proposed to highlight the relationship of the relative nonlinear parameter and fatigue degree of specimens; the fatigue life prediction model is built based on the relationship, and the prediction error is below 3%, which is below the prediction error based on the relative nonlinear parameters at the difference and sum frequencies. Therefore, the combined nonlinear ultrasonic parameter using the collinear wave mixing method can effectively estimate the fatigue degree of specimens, which provides a fast and convenient method for fatigue life prediction.

  5. Thermal conductivity studies of novel nanofluids based on metallic silver decorated mesoporous silica nanoparticles

    International Nuclear Information System (INIS)

    Tadjarodi, Azadeh; Zabihi, Fatemeh

    2013-01-01

    Graphical abstract: - Highlights: • Metallic silver was decorated in mSiO 2 with grafted hemiaminal functional groups. • Synthesized nanoparticles were used for preparation of glycerol based nanofluids. • The effect of temperature, weight fraction of mSiO 2 and concentration of silver nanoparticles on thermal conductivity of nanofluids was investigated. - Abstract: In the present study, the mesoporous structure of silica (mSiO 2 ) nanoparticles as well as hemiaminal grafted mSiO 2 decorated by metallic silver (Ag/mSiO 2 ) has been used for the preparation of glycerol based nanofluids. Structural and morphological characterization of the synthesized products have been carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), UV–vis spectroscopy, inductively coupled plasma (ICP) and N 2 adsorption–desorption isotherms. The thermal conductivity and viscosity of the nanofluids have been measured as a function of temperature for various weight fractions and silver concentrations of mSiO 2 and Ag/mSiO 2 nanoparticles, respectively. The results show that the thermal conductivity of the nanofluids increase up to 9.24% as the weight fraction of mSiO 2 increases up to 4 wt%. Also, increasing the percent of the silver decorated mSiO 2 (Ag/mSiO 2 ) up to 2.98% caused an enhancement in the thermal conductivity of the base fluid up to 10.95%. Furthermore, the results show that the nanofluids have Newtonian behavior in the tested temperature range for various concentrations of nanoparticles

  6. IMPROVED RISK ASSESSMENT AND REMEDIATION OF SOIL METALS BASED ON BIOAVAILABILITY MEASUREMENTS

    Science.gov (United States)

    Heavy metals in soils can comprise risk through plant uptake or soil ingestion. Recent research results and progress in understandings of risks and methods for soil metal remediation will be presented. Beneficial use of composts/bosolids plus limestone to remediate metal killed e...

  7. Benchmarking Anthropogenic Heavy Metals Emissions: Australian and Global Urban Environmental Health Risk Based Indicators of Sustainability

    Science.gov (United States)

    Dejkovski, Nick

    2016-01-01

    In Australia, the impacts of urbanisation and human activity are evident in increased waste generation and the emissions of metals into the air, land or water. Metals that have accumulated in urban soils almost exclusively anthropogenically can persist for long periods in the environment. Anthropogenic waste emissions containing heavy metals are a…

  8. Study on Gold and base metal occurrence in Uluwai Prospect, Western Latimojong Mountain, South Sulawesi

    Science.gov (United States)

    Maulana, Adi; Jaya, Asri; Imai, Akira

    2018-02-01

    Uluwai Prospect is located in the northern part of South Arm of Sulawesi along the eastern part of the Kalosi Fold Belt and Latimojong Mountain. The area is generally characterized by moderate to rugged topography area with elevation in the range of 700 to 1400 m above sea level in the mountainous complex called Latimojong Mountain Complex. The mineralization is characterized by a relatively simple sulphide ore mineral assemblage consists of pyrite, sphalerite and chalcopyrite. Samples were collected in areas showing abundant sulphide minerals where younger faults cut the bedding and foliation of country rocks. A number of silicified zones have been observed, as well as float material containing disseminated pyrite, chalcopyrite, and sphalerite with hematite, goethite and limonite. Some alteration types have been observed including sericitization, albitization, carbonatization and silisification. The samples collected indicated that the mineralisation is contained within metasedimentary (sandstone to mudstone) and greenschist. Geochemical analyses from 16 samples including 5 stream sediment samples indicated that the most promising mineralization occur in the prospect area are copper (Cu) and zinc (Zn). This is also supported by the abundance of chalcopyrite and sphalerite in some highly altered samples. Assaying of the collected samples revealed most of samples contain relatively low gold (Au) concentration. However, two samples contain 0.007 and 0.01 ppm of Au. In the mineralized area, Zn concentrations are up to 134 ppm, Cu up to 120 ppm and Pb up to 18 ppm and As up to 70 ppm. There is no clear relationship that exists between Au and the base metals except that one of the samples with highest Au values tend to have high Zn and As. This unclear pattern also shown by Cu, Pb and Zn. Base metal concentration in stream sediment samples show a relatively stable pattern than in rock samples. Arsenic tends to be elevated in base metal rich samples. Sb and Mo are

  9. Crack and wear behavior of SiC particulate reinforced aluminium based metal matrix composite fabricated by direct metal laser sintering process

    International Nuclear Information System (INIS)

    Ghosh, Subrata Kumar; Saha, Partha

    2011-01-01

    In this investigation, crack density and wear performance of SiC particulate (SiCp) reinforced Al-based metal matrix composite (Al-MMC) fabricated by direct metal laser sintering (DMLS) process have been studied. Mainly, size and volume fraction of SiCp have been varied to analyze the crack and wear behavior of the composite. The study has suggested that crack density increases significantly after 15 volume percentage (vol.%) of SiCp. The paper has also suggested that when size (mesh) of reinforcement increases, wear resistance of the composite drops. Three hundred mesh of SiCp offers better wear resistance; above 300 mesh the specific wear rate increases significantly. Similarly, there has been no improvement of wear resistance after 20 vol.% of reinforcement. The scanning electron micrographs of the worn surfaces have revealed that during the wear test SiCp fragments into small pieces which act as abrasives to result in abrasive wear in the specimen.

  10. Effect of chromium and phosphorus on the physical properties of iron and titanium-based amorphous metallic alloy films

    Science.gov (United States)

    Distefano, S.; Rameshan, R.; Fitzgerald, D. J.

    1991-01-01

    Amorphous iron and titanium-based alloys containing various amounts of chromium, phosphorus, and boron exhibit high corrosion resistance. Some physical properties of Fe and Ti-based metallic alloy films deposited on a glass substrate by a dc-magnetron sputtering technique are reported. The films were characterized using differential scanning calorimetry, stress analysis, SEM, XRD, SIMS, electron microprobe, and potentiodynamic polarization techniques.

  11. Synchrotron based x-ray fluorescence microscopy confirms copper in the corrosion products of metals in contact with treated wood

    Science.gov (United States)

    Samuel L. Zelinka; Joseph E. Jakes; Grant T. Kirker; David Vine; Stefan Vogt

    2017-01-01

    Copper based waterborne wood preservatives are frequently used to extend the service life of wood products when subjected to frequent moisture exposure. While these copper based treatments protect the wood from fungal decay and insect attack, they increase the corrosion of metals embedded or in contact with the treated wood. Previous research has shown the most...

  12. Development of Fe-based bulk metallic glasses as potential biomaterials.

    Science.gov (United States)

    Li, Shidan; Wei, Qin; Li, Qiang; Jiang, Bingliang; Chen, You; Sun, Yanfei

    2015-01-01

    A new series of Fe80-x-yCrxMoyP13C7 (x = 10, y = 10; x = 20, y = 5; x = 2 0, y = 10, all in at.%) bulk metallic glasses (BMGs) with the maximum diameter of 6mm have been developed for biomedical implant application by the combination method of fluxing treatment and J-quenching technique. The corrosion performance of the present Fe-based BMGs is investigated in both Hank's solution (pH = 7.4) and artificial saliva solution (pH = 6.3) at 37 °C by electrochemical measurements. The result indicates that the corrosion resistance of the present Fe-based BMGs in the above two simulated body solutions is much better than that of biomedical 316 L stainless steel (316 L SS), and approaching that of Ti6Al4V biomedical alloy (TC4). The concentrations of Fe, Ni and Cr ions released into the Hank's solution and artificial saliva solution from the present Fe-based BMGs after potentiodynamic polarization are significant lower than that released from 316 L SS. The biocompatibility of the present Fe-based BMGs is evaluated through the in vitro test of NIH3T3 cells culture in the present Fe-based BMG extraction media for 1, 3 and 5 days. The result indicates that the present Fe-based BMGs exhibit no cytotoxicity to NIH3T3 cells. And the test result of the cell adhesion and growth on the surface of the samples indicates that the present Fe-based BMGs exhibit the better cell viability compared with 316 L SS and TC4 biomedical alloys. The present Fe-based BMGs, especially Fe55Cr20Mo5P13C7 BMG, exhibit good glass formation ability, the high corrosion resistance and excellent biocompatibility, suggesting their promising potential as biomaterials. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. The Effect of the Use of Technological Lubricants Based on Vegetable Oils on the Process of Titanium Sheet Metal Forming

    Directory of Open Access Journals (Sweden)

    Więckowski W.

    2017-06-01

    Full Text Available The paper evaluates the drawability of titanium sheet metal Grade 2, with the focus on friction conditions that are present in the sheet metal forming process. The study aims to present the results of the examinations of the friction coefficient during a strip drawing test. The focus of the experiment was on lubricants based on vegetable oils i.e. rapeseed oil, sunflower oil and olive oil. Boric acid was used to improve the lubricating properties of vegetable oils. The results of numerical simulations of the process of forming a cover with stiffening components made of grade 2 titanium sheet metal was also presented. The numerical simulation was carried out using the FEM method with PAMStamp 2G software. The effect of conditions of friction between the sheet metal and tool parts and pressure force of the blank holder on the forming process were investigated. Numerical calculations were performed with consideration for the phenomenon of material strain hardening and anisotropy of plastic properties of the sheet metal formed. The analysis of the deformations and reduction in wall thickness of the drawn parts can be used for determination of the effect of changes in selected parameters on the process of drawn part forming. The quality of drawn parts was assessed based on the shape inaccuracy determined during simulation of forming. The inaccuracy depended on the conditions of the process and strength properties of the titanium sheet metal.

  14. Bio-rescue of marine environments: On the track of microbially-based metal/metalloid remediation.

    Science.gov (United States)

    Marques, Catarina R

    2016-09-15

    The recent awareness of the huge relevance of marine resources and ecological services is driving regulatory demands for their protection from overwhelming contaminants, such as metals/metalloids. These contaminants enter and accumulate in different marine niches, hence deeply compromising their quality and integrity. Bioremediation has been flourishing to counteract metal/metalloid impacts, since it provides cost-effective and sustainable options by relying on ecology-based technologies. The potential of marine microbes for metal/metalloid bioremediation is the core of many studies, due to their high plasticity to overcome successive environmental hurdles. However, any thorough review on the advances of metal/metalloid bioremediation in marine environments was so far unveiled. This review is designed to (i) outline the characteristics and potential of marine microbes for metal/metalloid bioremediation, (ii) describe the underlying pathways of resistance and detoxification, as well as useful methodologies for their characterization, (iii) identify major bottlenecks on metal/metalloid bioremediation with marine microbes, (iv) present alternative strategies based on microbial consortia and engineered microbes for enhanced bioremediation, and (v) propose key research avenues to keep pace with a changing society, science and economy in a sustainable manner. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. The study of metal contamination in urban soils of Hong Kong using a GIS-based approach

    International Nuclear Information System (INIS)

    Li Xiangdong; Lee Siulan; Wong Szechung; Shi Wenzhong; Thornton, Iain

    2004-01-01

    The study of regional variations and the anthropogenic contamination by metals of soils is very important for environmental planning and monitoring in urban areas. An extensive survey was conducted in the highly urbanized Kowloon area (46.9 km 2 ) of Hong Kong, using a systematic sampling strategy with a sampling density of 3-5 composite soil samples (0-15 cm) per km 2 . Geochemical maps of 'total' metals (Cd, Cr, Cu, Ni, Pb and Zn) from strong acid extraction in the surface soils were produced based on geographical information system (GIS) technology. A significant spatial relationship was found for Ni, Cu, Pb and Zn in the soils using a GIS-based analysis, suggesting that these metal contaminants in the soils of the Kowloon area had common sources. Several hot-spot areas of metal contamination were identified from the composite metal geochemical map, mainly in the old industrial and residential areas. A further GIS analysis revealed that road junctions, major roads and industrial buildings were possible sources of heavy metals in the urban soils. The Pb isotope composition of the contaminated soils showed clear anthropogenic origins. - GIS can be used to identify soil contamination hot-spot areas and to assess potential pollutant sources in an urban community

  16. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    Science.gov (United States)

    Gangwal, Santosh; Jothimurugesan, Kandaswamy

    1999-01-01

    A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

  17. Carbon based magnetism an overview of the magnetism of metal free carbon-based compounds and materials

    CERN Document Server

    Makarova, Tatiana

    2006-01-01

    Magnetism is one of the most intriguing phenomena observed in nature. Magnetism is relevant to physics and geology, biology and chemistry. Traditional magnets, an ubiquitous part of many everyday gadgets, are made of heavy iron- or nickel based materials. Recently there have been reports on the observation of magnetism in carbon, a very light and biocompatible element. Metal-free carbon structures exhibiting magnetic ordering represent a new class of materials and open a novel field of research that could lead to many new technologies. · The most complete, detailed, and accurate Guide in the magnetism of carbon · Dynamically written by the leading experts · Deals with recent scientific highlights · Gathers together chemists and physicists, theoreticians and experimentalists · Unified treatment rather than a series of individually authored papers · Description of genuine organic molecular ferromagnets · Unique description of new carbon materials with Curie temperatures well above ambient.

  18. Fly ash based geopolymer thin coatings on metal substrates and its thermal evaluation.

    Science.gov (United States)

    Temuujin, Jadambaa; Minjigmaa, Amgalan; Rickard, William; Lee, Melissa; Williams, Iestyn; van Riessen, Arie

    2010-08-15

    Class F fly ash based Na-geopolymer formulations have been applied as fire resistant coatings on steel. The main variables for the coating formulations were Si: Al molar and water: cement weight ratios. We have determined that the adhesive strength of the coatings strongly depend on geopolymer composition. The ease with which geopolymer can be applied onto metal surfaces and the resultant thickness depend on the water content of the formulation. Adhesive strengths of greater than 3.5 MPa have been achieved on mild steel surfaces for compositions with Si:Al of 3.5. Microstructure evolution and thermal properties of the optimised coating formulations show that they have very promising fire resistant characteristics. Copyright 2010 Elsevier B.V. All rights reserved.

  19. Production Methods of Van der Waals Heterostructures Based on Transition Metal Dichalcogenides

    Directory of Open Access Journals (Sweden)

    Haimei Qi

    2018-01-01

    Full Text Available Two dimensional (2D materials have gained significant attention since the discovery of graphene in 2004. Layered transition metal dichalcogenides (TMDs have become the focus of 2D materials in recent years due to their wide range of chemical compositions and a variety of properties. These TMDs layers can be artificially integrated with other layered materials into a monolayer (lateral or a multilayer stack (vertical heterostructures. The resulting heterostructures provide new properties and applications beyond their component 2D atomic crystals and many exciting experimental results have been reported during the past few years. In this review, we present the various synthesis methods (mechanical exfoliation, physical vapor transport, chemical vapor deposition, and molecular beam epitaxy method on van der Waals heterostructures based on different TMDs as well as an outlook for future research.

  20. Ni2+-based immobilized metal ion affinity chromatography of lactose operon repressor protein from Escherichia coli.

    Science.gov (United States)

    Velkov, Tony; Jones, Alun; Lim, Maria L R

    2008-01-01

    A two-step chromatographic sequence is described for the purification of native lactose operon repressor protein from Escherichia coli cells. The first step involves Ni(2+)-based immobilized metal ion affinity chromatography of the soluble cytoplasmic extract. This method provides superior speed, resolution and yield than the established phosphocellulose cation-exchange chromatographic procedure. Anion-exchange chromatography is used for further purification to >95% purity. The identity and purity of the lactose repressor protein were demonstrated using sodium dodecylsulphate polyacrylamide electrophoresis, crystallization, tryptic finger-printing mass spectrometry, and inducer binding assays. The purified lac repressor exhibited inducer sensitivity for operator DNA binding and undergoes a conformational change upon inducer binding. By all these extensive biochemical criteria, the purified protein behaves exactly as that described for the Escherichia coli lactose operon repressor.

  1. Development of friction welding process of Zr-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Shin, Hyung Seop; Jeong, Young Jin; Kim, Ki Hyun

    2004-01-01

    Bulk Metallic Glasses(BMG) with good mechanical properties have problems that engineering application fields have been limited because of limitation of the alloy size. In order to solving this problem, the friction welding of BMG has been tried using the superplastic-like deformation behavior under the supercooled liquid region. The apparatus for friction welding test was designed and constructed using pneumatic cylinder and gripper based on a conventional lathe. Friction welding have been tried to combination of same BMG alloy and crystalline alloys. The results of welding test were evaluated by X-ray diffraction, measurement of hardness and mechanical properties test. In order to obtain the optimized welding test conditions the temperature of friction interface was measured using Infrared thermal imager

  2. Impedance-Matched, Double-Zero Optical Metamaterials Based on Weakly Resonant Metal Oxide Nanowires

    Directory of Open Access Journals (Sweden)

    Diego R. Abujetas

    2018-03-01

    Full Text Available Artificial optical metamaterial with a zero index of refraction holds promise for many diverse phenomena and applications, which can be achieved with vacuum (or related surface impedance and materials in the optical domain. Here, we propose simple metal-oxide nanorods as meta-atoms on the basis of an effective medium approach, based on their weak overlapping (electric/magnetic resonances. We thus studied the optical properties of TiO 2 nanowire arrays with a high-filling fraction through their photonic band structure, which exhibits a double-degeneracy point without a band gap at the center of the Brillouin zone. Various configurations are considered that reveal their performance over a reasonable range of incident wave vectors as impedance-matched, double-zero, bulk (low-loss metamaterials.

  3. Hybrid materials based on polymethylsilsesquioxanes containing Fe, Pt, and Fe-Pt metallic nanoparticles

    Science.gov (United States)

    Vasil'kov, A. Yu.; Migulin, D. A.; Naumkin, A. V.; Zubavichus, Ya. V.; Budnikov, A. V.; Ellert, O. G.; Maksimov, Yu. V.; Muzafarov, A. M.

    2017-11-01

    New hybrid materials based on Pt, Fe, and Pt-Fe nanoparticles stabilized in a matrix of polymethylsilsesquioxane nanogel and ultrahigh molecular weight polyethylene (UHMWPE) were prepared. Metal vapor synthesis was used to produce mono- and bimetallic nanoparticles. It was shown that organosilicon nanogel effectively stabilizes Pt nanoparticles with an average size of 0.9 nm. Using the nanogel results in the formation of superparamagnetic Fe particles 3-5 nm in size that consist of ferromagnetic Fe0 core and antiferromagnetic shells of Fe oxides. It is established that using an organosilicon matrix in the formation of Pt-Fe/UHMWPE systems helps reduce the average particle size of Fe in the material from 6.5 to 4.5 nm and narrow their particle size distribution. The composition, magnetic and electronic characteristics of the nanocomposites are studied via transmission electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, XANES, and EXAFS.

  4. Coal fly ash-slag-based geopolymers: Microstructure and metal leaching

    International Nuclear Information System (INIS)

    Izquierdo, Maria; Querol, Xavier; Davidovits, Joseph; Antenucci, Diano; Nugteren, Henk; Fernandez-Pereira, Constantino

    2009-01-01

    This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilise a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.

  5. Development of Chemosorbent Based on Metallic Waste for Cleaning Mine Water From Molybdenum

    Directory of Open Access Journals (Sweden)

    Alexander Evgenyevich Isakov

    2018-01-01

    Full Text Available The article presents the results of hydrochemical studies of water objects, located in the impact zone of one of the largest mining enterprises in the Russian Federation – JSC “Apatite”. According to the monitoring studies, the source of surface water pollution with molybdenum was determined, geochemical assessment of the molybdenum transformation in the system “ore-bearing rocks – mine water – surface water” was performed. In order to reduce the technogenic load on the surface water located in the considered area, the way of large-tonnage mine waters purificationfrom molybdenum was proposed. The method involves using the chemical sorbent based on waste metals. The method of sewage purificationwill allow solving one of the key environmental problems of the considered enterprise and, in addition, to improve the environmental situation in the considered area as well as the quality of the local population life.

  6. Glass Formation, Chemical Properties and Surface Analysis of Cu-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Akihisa Inoue

    2011-04-01

    Full Text Available This paper reviews the influence of alloying elements Mo, Nb, Ta and Ni on glass formation and corrosion resistance of Cu-based bulk metallic glasses (BMGs. In order to obtain basic knowledge for application to the industry, corrosion resistance of the Cu–Hf–Ti–(Mo, Nb, Ta, Ni and Cu–Zr–Ag–Al–(Nb bulk glassy alloy systems in various solutions are reported in this work. Moreover, X-ray photoelectron spectroscopy (XPS analysis is performed to clarify the surface-related chemical characteristics of the alloy before and after immersion in the solutions; this has lead to a better understanding of the correlation between the surface composition and the corrosion resistance.

  7. Revealing homogeneous plastic deformation in dendrite-reinforced Ti-based metallic glass composites under tension

    Science.gov (United States)

    Wu, F. F.; Wei, J. S.; Chan, K. C.; Chen, S. H.; Zhao, R. D.; Zhang, G. A.; Wu, X. F.

    2017-01-01

    The tensile plastic deformation of dendrite-reinforced Ti-based metallic glass composites (MGCs) was investigated. It was found that there is a critical normalized strain-hardening rate (NSHR) that determines the plastic stability of MGCs: if the NSHR is larger than the critical value, the plastic deformation of the MGCs will be stable, i.e. the necking and strain localization can be effectively suppressed, resulting in homogeneous plastic elongation. In addition, dendrite-reinforce MGCs are verified as being intrinsically ductile, and can be used as good coatings for improving the surface properties of pure titanium or titanium alloys. These findings are helpful in designing, producing, and using MGCs with improved performance properties. PMID:28195216

  8. Novel synthetic phytochelatin-based capacitive biosensor for heavy metal ion detection.

    Science.gov (United States)

    Bontidean, Ibolya; Ahlqvist, Josefin; Mulchandani, Ashok; Chen, Wilfred; Bae, Weon; Mehra, Rajesh K; Mortari, Alessia; Csöregi, Elisabeth

    2003-05-01

    A novel capacitance biosensor based on synthetic phytochelatins for sensitive detection of heavy metals is described. Synthetic phytochelatin (Glu-Cys)(20)Gly (EC20) fused to the maltose binding domain protein was expressed in Escherichia coli and purified for construction of the biosensor. The new biosensor was able to detect Hg(2+), Cd(2+), Pb(2+), Cu(2+) and Zn(2+) ions in concentration range of 100 fM-10 mM, and the order of sensitivity was S(Zn)>S(Cu)>S(Hg)>S(Cd) congruent with S(Pb). The biological sensing element of the sensor could be regenerated using EDTA and the storage stability of the biosensor was 15 days.

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

    Science.gov (United States)

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

    2013-10-01

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

  10. Mechanical and corrosion behaviors of developed copper-based metal matrix composites

    Science.gov (United States)

    Singh, Manvandra Kumar; Gautam, Rakesh Kumar; Prakash, Rajiv; Ji, Gopal

    2018-03-01

    This work investigates mechanical properties and corrosion resistances of cast copper-tungsten carbide (WC) metal matrix composites (MMCs). Copper matrix composites have been developed by stir casting technique. Different sizes of micro and nano particles of WC particles are utilized as reinforcement to prepare two copper-based composites, however, nano size of WC particles are prepared by high-energy ball milling. XRD (X-rays diffraction) characterize the materials for involvement of different phases. The mechanical behavior of composites has been studied by Vickers hardness test and compression test; while the corrosion behavior of developed composites is investigated by electrochemical impedance spectroscopy in 0.5 M H2SO4 solutions. The results show that hardness, compressive strength and corrosion resistance of copper matrix composites are very high in comparison to that of copper matrix, which attributed to the microstructural changes occurred during composite formation. SEM (Scanning electron microscopy) reveals the morphology of the corroded surfaces.

  11. Titanium-Phosphonate-Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

    KAUST Repository

    Li, Hui

    2018-02-01

    Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. Herein a new photocatalyst of hierarchically mesoporous titanium-phosphonate-based metal-organic frameworks, featuring well-structured spheres, periodic mesostructure and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemical field.

  12. Heterogeneities in CuZr-based bulk metallic glasses studied by x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X D; Lou, H B; Gong, Y; Jiang, J Z [International Center for New-Structured Materials (ICNSM), Zhejiang University (China); Vainio, U, E-mail: wangxd@zju.edu.cn, E-mail: jiangjz@zju.edu.cn [HASYLAB at DESY, Notkestrasse 85, D-22607 Hamburg (Germany)

    2011-02-23

    Inhomogeneities in two CuZr-based bulk metallic glasses (BMGs) were studied by using synchrotron radiation x-ray scattering techniques. (Cu{sub 4.5/5.5}Ag{sub 1/5.5}){sub 46}Zr{sub 46}Al{sub 8} BMG was found to be more inhomogeneous than Cu{sub 46}Zr{sub 46}Al{sub 8} BMG on the small length scale, where Cu and Ag atoms form enriched zones. Such heterogeneities are locally favorable for forming close-packed icosahedron-like clusters in three-dimensional space, greatly promoting the glass forming ability of this alloy. Upon annealing near the T{sub g} temperature, the heterogeneities were reduced initially at low temperature and short time annealing, then regenerated again for temperature increase and time extension. The average environment around Zr atoms almost does not change. However, the heterogeneity increases for Cu, Zr and Ag atoms once nanocrystallization happens.

  13. N-aryl pyrrolo-tetrathiafulvalene based ligands: synthesis and metal coordination.

    Science.gov (United States)

    Balandier, Jean-Yves; Chas, Marcos; Dron, Paul I; Goeb, Sébastien; Canevet, David; Belyasmine, Ahmed; Allain, Magali; Sallé, Marc

    2010-03-05

    A straightforward general synthetic access to N-aryl-1,3-dithiolo[4,5-c]pyrrole-2-thione derivatives 6 from acetylenedicarbaldehyde monoacetal is depicted. In addition to their potentiality as precursors to dithioalkyl-pyrrole derivatives, thiones 6 are key building blocks to N-aryl monopyrrolo-tetrathiafulvalene (MPTTF) derivatives 10. X-ray structures of four of these thiones intermediates, reminiscent of the corresponding MPTTF derivatives, are provided. When the aryl group is a binding pyridyl unit, the MPTTF derivative 10a can coordinate M(II) salts (M = Pt, Pd). The first examples of metal-directed orthogonal MPTTF-based dimers 11-14, obtained through coordination of 10a to cis-blocked square planar Pt or Pd complexes are described. Studies on the parameters influencing the dimer construction are presented, as well as first recognition properties of the resulting electron-rich clip for C(60).

  14. A biomimetic jellyfish robot based on ionic polymer metal composite actuators

    International Nuclear Information System (INIS)

    Yeom, Sung-Weon; Oh, Il-Kwon

    2009-01-01

    A biomimetic jellyfish robot based on ionic polymer metal composite actuators was fabricated and activated to mimic real locomotive behavior with pulse and recovery processes. To imitate the curved shape of the jellyfish, a thermal treatment was applied to obtain a permanent initial deformation of a hemispherical form. The bio-inspired input signal was generated for mimicking real locomotion of the jellyfish. The vertical floating displacement and the thrust force of the biomimetic jellyfish robot under various input signals were measured and compared. The present results show that the bio-inspired electrical input signal with pulse-recovery process generates much higher floating velocity of the biomimetic jellyfish robot in comparison with pure sinusoidal excitations. The curved shape of the IPMC actuator through thermal treatments can be successfully applied to mimic the real biomimetic robots with smooth curves

  15. Light Hydrocarbons Adsorption Mechanisms in Two Calcium-based Microporous Metal Organic Frameworks

    KAUST Repository

    Plonka, Anna M.

    2016-01-25

    The adsorption mechanism of ethane, ethylene and acetylene (C2Hn; n=2, 4, 6) on two microporous metal organic frameworks (MOFs) is described here that is consistent with observations from single crystal and powder X-ray diffraction, calorimetric measurments and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined form single crystal diffraction experiments channel geometries of both SBMOF-1 and SBMOF-2 provide multiple adsorption sites for hydrocarbon molecules trough C-H…π and C-H…O interactions, similarly to interactions in the molecular and protein crystals. Both materials selectively adsorb C2 hydrocarbon gases over methane as determined with IAST and breakthrough calculations, with C2H6/CH4 selectivity as high as 74 in SBMOF-1.

  16. Micromechanical modeling of tungsten-based bulk metallic glass matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Li Hao [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 (United States); Li Ke [Department of Mechanical Engineering, Texas A and M University, TAMU 3123, College Station, TX 77843 (United States)]. E-mail: keli@tamu.edu; Subhash, Ghatu [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 (United States); Kecskes, Laszlo J. [Weapons and Materials Research Directorate, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Dowding, Robert J. [Weapons and Materials Research Directorate, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States)

    2006-08-15

    Micromechanics models are developed for tungsten (W)-based bulk metallic glass (BMG) matrix composites employing the Voronoi tessellation technique and the finite element (FE) method. The simulation results indicate that the computed elastic moduli are close to those measured in the experiments. The predicted stress-strain curves agree well with their experimentally obtained counterparts in the early stage of the plastic deformation. An increase in the W volume fraction leads to a decrease in the yield stress and an increase in the Young's modulus of the composite. In addition, contours of equivalent plastic strain for increasing applied strains provide an explanation why shear bands were observed in the glassy phase, along the W/BMG interface, and in the W phase of failed W/BMG composite specimens.

  17. Feedback Linearization Based Arc Length Control for Gas Metal Arc Welding

    DEFF Research Database (Denmark)

    Thomsen, Jesper Sandberg

    2005-01-01

    In this paper a feedback linearization based arc length controller for gas metal arc welding (GMAW) is described. A nonlinear model describing the dynamic arc length is transformed into a system where nonlinearities can be cancelled by a nonlinear state feedback control part, and thus, leaving only...... a linear system to be controlled by linear state feedback control. The advantage of using a nonlinear approach as feedback linearization is the ability of this method to cope with nonlinearities and different operating points. However, the model describing the GMAW process is not exact, and therefore......, the cancellation of nonlinear terms might give rise to problems with respect to robustness. Robustness of the closed loop system is therefore nvestigated by simulation....

  18. Analytical applications of some macro-schiff's bases for spectrophotometric determination of some metal ions

    International Nuclear Information System (INIS)

    Ahmed, N. A. M.

    2005-06-01

    In this research three schiff's bases PAD, N, NBPAD and N, NBHPAD were synthesized by condensation of o-phenylenediamine with p-aminoacetophenone, to give an intermediate which then further condensed with benzil, and 2,5 hexanedione, respectively, in ethanol to give macro schiff's bases. These schiff's bases were identified using I.R spectra, UV/VIS spectrophotometer, elemental analyzer, and melting point. Their applications as analytical reagents were studied using UV/VIS spectrophotometer with Pb(II), Cr(VI), Cu(II), Cd(II), V(V), Ni(II), Hg(II), Zn(II), Co(II), Fe(II) and Fe(III). Various parameters were investigated in order to find their optimum conditions for the analytical application of these schiff's bases. These include the effect of solvent, the effect of micelle as well as the presence of foreign metal ions. Good results were obtained for determination of Cr(VI), and V(V) with N, NBPAD in terms of linearity detection limit, and interference, and for the determination of Fe(II) with N, NBHPAD. The stoichiometry of some these complexes was determined. The study also showed a good results for the determination of Hg(II), and Pb(II) (two serious environmental pollutants) if interference is removed.(Author)

  19. MOORA-Based Tribological Studies on Red Mud Reinforced Aluminum Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    S. Rajesh

    2013-01-01

    Full Text Available This paper presents the findings of an experimental investigation on the effects of applied load, sliding velocity, wt.% of reinforcement and hardness of the counterface material in dry sliding wear studies performed on red mud-based aluminum metal matrix composites (MMC. The specific wear rate and the coefficient of friction are considered as the output quality characteristics. Taguchi-based L9 orthogonal array has been used to accomplish the objective of the experimental study. Analysis of variance (ANOVA is employed to find the optimal setting and the effect of each parameter on the output performance characteristics. It has been observed that optimal factor setting for each output performance is different. In order to minimize the two responses simultaneously, multiobjective optimization based on ratio analysis (MOORA is adopted. MOORA revealed that the optimal combination of the dry sliding wear parameters for the multiperformance characteristics of the red mud based aluminium is the set normal load at 20 N, sliding velocity 3 m/s, % of reinforcement 20%, and counterface hardness of the material 58 HRC.

  20. Fuzzy logic based sensor performance evaluation of vehicle mounted metal detector systems

    Science.gov (United States)

    Abeynayake, Canicious; Tran, Minh D.

    2015-05-01

    Vehicle Mounted Metal Detector (VMMD) systems are widely used for detection of threat objects in humanitarian demining and military route clearance scenarios. Due to the diverse nature of such operational conditions, operational use of VMMD without a proper understanding of its capability boundaries may lead to heavy causalities. Multi-criteria fitness evaluations are crucial for determining capability boundaries of any sensor-based demining equipment. Evaluation of sensor based military equipment is a multi-disciplinary topic combining the efforts of researchers, operators, managers and commanders having different professional backgrounds and knowledge profiles. Information acquired through field tests usually involves uncertainty, vagueness and imprecision due to variations in test and evaluation conditions during a single test or series of tests. This report presents a fuzzy logic based methodology for experimental data analysis and performance evaluation of VMMD. This data evaluation methodology has been developed to evaluate sensor performance by consolidating expert knowledge with experimental data. A case study is presented by implementing the proposed data analysis framework in a VMMD evaluation scenario. The results of this analysis confirm accuracy, practicability and reliability of the fuzzy logic based sensor performance evaluation framework.