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Sample records for metal organic chemical

  1. 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.

  2. Destruction of chemical warfare agents using metal-organic frameworks

    Science.gov (United States)

    Mondloch, Joseph E.; Katz, Michael J.; Isley, William C., III; Ghosh, Pritha; Liao, Peilin; Bury, Wojciech; Wagner, George W.; Hall, Morgan G.; Decoste, Jared B.; Peterson, Gregory W.; Snurr, Randall Q.; Cramer, Christopher J.; Hupp, Joseph T.; Farha, Omar K.

    2015-05-01

    Chemical warfare agents containing phosphonate ester bonds are among the most toxic chemicals known to mankind. Recent global military events, such as the conflict and disarmament in Syria, have brought into focus the need to find effective strategies for the rapid destruction of these banned chemicals. Solutions are needed for immediate personal protection (for example, the filtration and catalytic destruction of airborne versions of agents), bulk destruction of chemical weapon stockpiles, protection (via coating) of clothing, equipment and buildings, and containment of agent spills. Solid heterogeneous materials such as modified activated carbon or metal oxides exhibit many desirable characteristics for the destruction of chemical warfare agents. However, low sorptive capacities, low effective active site loadings, deactivation of the active site, slow degradation kinetics, and/or a lack of tailorability offer significant room for improvement in these materials. Here, we report a carefully chosen metal-organic framework (MOF) material featuring high porosity and exceptional chemical stability that is extraordinarily effective for the degradation of nerve agents and their simulants. Experimental and computational evidence points to Lewis-acidic ZrIV ions as the active sites and to their superb accessibility as a defining element of their efficacy.

  3. Metal organic frameworks for the catalytic detoxification of chemical warfare nerve agents

    Science.gov (United States)

    Hupp, Joseph T.; Farha, Omar K.; Katz, Michael J.; Mondloch, Joseph E.

    2017-04-18

    A method of using a metal organic framework (MOF) comprising a metal ion and an at least bidendate organic ligand to catalytically detoxify chemical warfare nerve agents including exposing the metal-organic-framework (MOF) to the chemical warfare nerve agent and catalytically decomposing the nerve agent with the MOF.

  4. Direct conversion of radioactive and chemical waste containing metals, ceramics, amorphous solids, and organics to glass

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

    1994-01-01

    The Glass Material Oxidation and Dissolution System (CMODS) is a new process for direct conversion of radioactive, mixed, and chemical wastes to glass. The wastes can be in the chemical forms of metals, ceramics, amorphous solids, and organics. GMODS destroys organics and it incorporates heavy metals and radionuclides into a glass. Processable wastes may include miscellaneous spent fuels (SF), SF hulls and hardware, plutonium wastes in different forms, high-efficiency particulate air (HEPA) filters, ion-exchange resins, failed equipment, and laboratory wastes. Thermodynamic calculations indicate theoretical feasibility. Small-scale laboratory experiments (< 100 g per test) have demonstrated chemical laboratory feasibility for several metals. Additional work is needed to demonstrate engineering feasibility

  5. Properties of alumina films by atmospheric pressure metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.

    1994-01-01

    Thin alumina films were deposited at low temperatures (290–420°C) on stainless steel, type AISI 304. The deposition process was carried out in nitrogen by metal-organic chemical vapour deposition using aluminum tri-sec-butoxide. The film properties including the protection of the underlying

  6. The mechanical properties of thin alumina film deposited by metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; Gellings, P.J.; van de Vendel, D.; Metselaar, H.S.C.; van Corbach, H.D.; Fransen, T.

    1995-01-01

    Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low and atmospheric pressures. The effects of deposition temperature, growth rate and film thickness on the mechanical

  7. Luminescent metal-organic frameworks for chemical sensing and explosive detection.

    Science.gov (United States)

    Hu, Zhichao; Deibert, Benjamin J; Li, Jing

    2014-08-21

    Metal-organic frameworks (MOFs) are a unique class of crystalline solids comprised of metal cations (or metal clusters) and organic ligands that have shown promise for a wide variety of applications. Over the past 15 years, research and development of these materials have become one of the most intensely and extensively pursued areas. A very interesting and well-investigated topic is their optical emission properties and related applications. Several reviews have provided a comprehensive overview covering many aspects of the subject up to 2011. This review intends to provide an update of work published since then and focuses on the photoluminescence (PL) properties of MOFs and their possible utility in chemical and biological sensing and detection. The spectrum of this review includes the origin of luminescence in MOFs, the advantages of luminescent MOF (LMOF) based sensors, general strategies in designing sensory materials, and examples of various applications in sensing and detection.

  8. Pulsed injection metal organic chemical vapour deposition and characterisation of thin CaO films

    Energy Technology Data Exchange (ETDEWEB)

    Borges, R.P., E-mail: rpborges@fc.ul.p [Centro de Fisica da Materia Condensada, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Ferreira, P. [Departamento de Engenharia Ceramica e do Vidro, CICECO, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Saraiva, A. [Centro de Fisica da Materia Condensada, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Goncalves, R., E-mail: rjbarrosog@hotmail.co [Centro de Fisica da Materia Condensada, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Rosa, M.A. [Centro de Fisica da Materia Condensada, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Goncalves, A.P. [Centro de Fisica da Materia Condensada, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Departamento de Quimica, Instituto Tecnologico e Nuclear, P-2686-953 Sacavem (Portugal); Silva, R.C. da [Laboratorio de Feixe de Ioes, Dep. Fisica, Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Magalhaes, S. [Laboratorio de Feixe de Ioes, Dep. Fisica, Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Lourenco, M.J.V.; Santos, F.J.V. [Centro de Ciencias Moleculares e Materiais, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016, Lisboa (Portugal); Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Godinho, M. [Centro de Fisica da Materia Condensada, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Dep. de Fisica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal)

    2009-05-01

    Thin films of CaO were grown on silicon (Si) and lanthanum aluminate (LaAlO{sub 3}) substrates by pulsed injection metal-organic chemical vapour deposition in a vertical injection MOCVD system. Growth parameters were systematically varied to study their effect on film growth and quality and to determine the optimal growth conditions for this material. Film quality and growth rate were evaluated by atomic force microscopy, X-ray diffraction and Rutherford Backscattering Spectroscopy measurements. Optimised conditions allowed growing transparent, single phase films textured along the (0 0 l) direction.

  9. Half-sandwich cobalt complexes in the metal-organic chemical vapor deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Georgi, Colin [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Hapke, Marko; Thiel, Indre [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Straße 29a, Rostock 18059 (Germany); Hildebrandt, Alexander [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Institute of Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz 09126 (Germany); Technische Universität Chemnitz, Center for Microtechnologies (ZfM), Chemnitz 09107 (Germany); Lang, Heinrich, E-mail: heinrich.lang@chemie.tu-chemnitz.de [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany)

    2015-03-02

    A series of cobalt half-sandwich complexes of type [Co(η{sup 5}-C{sub 5}H{sub 5})(L)(L′)] (1: L, L′ = 1,5-hexadiene; 2: L = P(OEt){sub 3}, L′ = H{sub 2}C=CHSiMe{sub 3}; 3: L = L′ = P(OEt){sub 3}) has been studied regarding their physical properties such as the vapor pressure, decomposition temperature and applicability within the metal-organic chemical vapor deposition (MOCVD) process, with a focus of the influence of the phosphite ligands. It could be shown that an increasing number of P(OEt){sub 3} ligands increases the vapor pressure and thermal stability of the respective organometallic compound. Complex 3 appeared to be a promising MOCVD precursor with a high vapor pressure and hence was deposited onto Si/SiO{sub 2} (100 nm) substrates. The resulting reflective layer is closed, dense and homogeneous, with a slightly granulated surface morphology. X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of metallic cobalt, cobalt phosphate, cobalt oxide and cobalt carbide. - Highlights: • Thermal studies and vapor pressure measurements of cobalt half-sandwich complexes was carried out. • Chemical vapor deposition with cobalt half-sandwich complexes is reported. • The use of Co-phosphites results in significant phosphorous-doped metallic layers.

  10. 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.

  11. Computational Investigations of Potential Energy Function Development for Metal--Organic Framework Simulations, Metal Carbenes, and Chemical Warfare Agents

    Science.gov (United States)

    Cioce, Christian R.

    Metal-Organic Frameworks (MOFs) are three-dimensional porous nanomaterials with a variety of applications, including catalysis, gas storage and separation, and sustainable energy. Their potential as air filtration systems is of interest for designer carbon capture materials. The chemical constituents (i.e. organic ligands) can be functionalized to create rationally designed CO2 sequestration platforms, for example. Hardware and software alike at the bleeding edge of supercomputing are utilized for designing first principles-based molecular models for the simulation of gas sorption in these frameworks. The classical potentials developed herein are named PHAST --- Potentials with High Accuracy, Speed, and Transferability, and thus are designed via a "bottom-up" approach. Specifically, models for N2 and CH4 are constructed and presented. Extensive verification and validation leads to insights and range of applicability. Through this experience, the PHAST models are improved upon further to be more applicable in heterogeneous environments. Given this, the models are applied to reproducing high level ab initio energies for gas sorption trajectories of helium atoms in a variety of rare-gas clusters, the geometries of which being representative of sorption-like environments commonly encountered in a porous nanomaterial. This work seeks to push forward the state of classical and first principles materials modeling. Additionally, the characterization of a new type of tunable radical metal---carbene is presented. Here, a cobalt(II)---porphyrin complex, [Co(Por)], was investigated to understand its role as an effective catalyst in stereoselective cyclopropanation of a diazoacetate reagent. Density functional theory along with natural bond order analysis and charge decomposition analysis gave insight into the electronics of the catalytic intermediate. The bonding pattern unveiled a new class of radical metal---carbene complex, with a doublet cobalt into which a triplet carbene

  12. Exploiting Diffusion Barrier and Chemical Affinity of Metal-Organic Frameworks for Efficient Hydrogen Isotope Separation.

    Science.gov (United States)

    Kim, Jin Yeong; Balderas-Xicohténcatl, Rafael; Zhang, Linda; Kang, Sung Gu; Hirscher, Michael; Oh, Hyunchul; Moon, Hoi Ri

    2017-10-25

    Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern separation technology. However, current commercial approaches suffer from extremely low separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale separation technique. Herein, we report a highly effective hydrogen isotope separation system based on metal-organic frameworks (MOFs) having the highest reported separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sites is chosen for CAQS functionality, and imidazole molecules (IM) are employed to the system for enhancing the KQS effect. To the best of our knowledge, this work is not only the first attempt to implement two quantum sieving effects, KQS and CAQS, in one system, but also provides experimental validation of the utility of this system for practical industrial usage by isolating high-purity D 2 through direct selective separation studies using 1:1 D 2 /H 2 mixtures.

  13. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-02-07

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  14. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-08-22

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  15. Study of the occurrence of organic matter, metals and chemicals in the SFR

    International Nuclear Information System (INIS)

    Sundqvist, J.O.

    2001-03-01

    Low- and intermediate level operational waste from the Swedish nuclear power plants, and the Studsvik facility, is currently placed in a repository, termed SFR-l (final repository for radioactive operational waste) near the Forsmark power plant. Two important components in the waste, which can affect the function of the repository, are organic materials, e.g. cloth and paper, and metals (scrap). The release of radionuclides from the repository may be affected by chemical reactions that involve both organic materials and metals. After sealing the repository, the conditions can be such that complexing agents (e.g. isosaccarinic acid) may form when organic materials degrade. These agents typically increase the mobility of radionuclides. Formation of gas, mainly due to metal corrosion, may affect the barrier system, surrounding the waste, such that the release of radionuclides is enhanced. SKB makes an annual report with a compilation of the waste that has been placed in SFR-l . The compilation contains both the amount of waste placed in the repository during the last year and a compilation of the waste that have been placed since the stall of SFR. Moreover, SKB provides a prognosis of the future situation in SFR-1 every third year. SKI (the Swedish Nuclear Power Inspectorate), is responsible for reviewing this reporting. This study was initiated with the purpose of evaluating the uncertainties in SKB's estimates of the amounts of organic matter, metals and chemicals in the waste in SFR- I. The estimates of the quantities of e.g. cellulose and metals in the waste are based on a method which is utilising what is called normal-containers. The waste is classified into certain waste categories. For each waste category there is a specified, presumed composition, named normal-container. The results of this study suggest that the documentation provided by SKB is lacking in some respects. There are for instance examples of incomplete notification of waste and container types

  16. Research Update: Mechanical properties of metal-organic frameworks – Influence of structure and chemical bonding

    Directory of Open Access Journals (Sweden)

    Wei Li

    2014-12-01

    Full Text Available Metal-organic frameworks (MOFs, a young family of functional materials, have been attracting considerable attention from the chemistry, materials science, and physics communities. In the light of their potential applications in industry and technology, the fundamental mechanical properties of MOFs, which are of critical importance for manufacturing, processing, and performance, need to be addressed and understood. It has been widely accepted that the framework topology, which describes the overall connectivity pattern of the MOF building units, is of vital importance for the mechanical properties. However, recent advances in the area of MOF mechanics reveal that chemistry plays a major role as well. From the viewpoint of materials science, a deep understanding of the influence of chemical effects on MOF mechanics is not only highly desirable for the development of novel functional materials with targeted mechanical response, but also for a better understanding of important properties such as structural flexibility and framework breathing. The present work discusses the intrinsic connection between chemical effects and the mechanical behavior of MOFs through a number of prototypical examples.

  17. Corrosion resistant coatings (Al@#2@#O@#3@#) produced by metal-organic chemical vapour deposition using ATSB

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.

    1993-01-01

    The metal organic chemical vapour deposition (MOCVD) of amorphous alumina films on steel was performed in nitrogen at atmospheric pressure. This MOCVD process is based on the thermal decomposition of aluminium-tri-sec-butoxide (ATSB). The effect of the deposition temperature (within the range

  18. Two level undercut-profile substrate-based filamentary coated conductors produced using metal organic chemical vapor deposition

    DEFF Research Database (Denmark)

    Insinga, Andrea R.; Sundaram, Aarthi; Hazelton, Drew W.

    2018-01-01

    of a filamentary CC produced in an industrial setup by SuperPower Inc. using ion beam assisted deposition and metal organic chemical vapor deposition (IBAD-MOCVD) on a 2LUPS substrate realized at the Technical University of Denmark (DTU), whereas previous studies discussed the fabrication using alternating beam...

  19. A novel three-jet microreactor for localized metal-organic chemical vapour deposition of gallium arsenide : Design and simulation

    NARCIS (Netherlands)

    Konakov, S.A.; Krzhizhanovskaya, V.V.

    2016-01-01

    We present a novel three-jet microreactor design for localized deposition of gallium arsenide (GaAs) by low-pressure Metal-Organic Chemical Vapour Deposition (MOCVD) for semiconductor devices, microelectronics and solar cells. Our approach is advantageous compared to the standard lithography and

  20. Deposition of highly (111)-oriented PZT thin films by using metal organic chemical deposition

    CERN Document Server

    Bu, K H; Choi, D K; Seong, W K; Kim, J D

    1999-01-01

    Lead zirconate titanate (PZT) thin films have been grown on Pt/Ta/SiNx/Si substrates by using metal organic chemical vapor deposition with Pb(C sub 2 H sub 5) sub 4 , Zr(O-t-C sub 4 H sub 9) sub 4 , and Ti(O-i-C sub 3 H sub 7) sub 4 as source materials and O sub 2 as an oxidizing gas. The Zr fraction in the thin films was controlled by varying the flow rate of the Zr source material. The crystal structure and the electrical properties were investigated as functions of the composition. X-ray diffraction analysis showed that at a certain range of Zr fraction, highly (111)-oriented PZT thin films with no pyrochlore phases were deposited. On the other hand, at low Zr fractions, there were peaks from Pb-oxide phases. At high Zr fractions, peaks from pyrochlore phase were seen. The films also showed good electrical properties, such as a high dielectric constant of more than 1200 and a low coercive voltage of 1.35 V.

  1. Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jagdale, Pravin, E-mail: pravin.jagdale@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy); Castellino, Micaela [Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Marrec, Françoise [Laboratory of Condensed Matter Physics, University of Picardie Jules Verne (UPJV), Amiens 80039 (France); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexicom (UNAM), Mexico D.F. 04510 (Mexico); Tagliaferro, Alberto [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy)

    2014-06-01

    Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl{sub 3}) in acetone (CH{sub 3}-CO-CH{sub 3}). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18–250 nm thick and a few micrometres wide.

  2. Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

    International Nuclear Information System (INIS)

    Jagdale, Pravin; Castellino, Micaela; Marrec, Françoise; Rodil, Sandra E.; Tagliaferro, Alberto

    2014-01-01

    Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl 3 ) in acetone (CH 3 -CO-CH 3 ). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18–250 nm thick and a few micrometres wide.

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

    Science.gov (United States)

    Gao, Wenyang

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

  4. Stress-induced chemical detection using flexible metal-organic frameworks.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Hesketh, Peter J. (Georgia Institute of Technology, Atlanta, GA); Gall, Kenneth A. (Georgia Institute of Technology, Atlanta, GA); Choudhury, A. (Georgia Institute of Technology, Atlanta, GA); Pikarsky, J. (Georgia Institute of Technology, Atlanta, GA); Andruszkiewicz, Leanne (Georgia Institute of Technology, Atlanta, GA); Houk, Ronald J. T.; Talin, Albert Alec (National Institute of Standards & Technology, Gaithersburg, MD)

    2009-09-01

    In this work we demonstrate the concept of stress-induced chemical detection using metal-organic frameworks (MOFs) by integrating a thin film of the MOF HKUST-1 with a microcantilever surface. The results show that the energy of molecular adsorption, which causes slight distortions in the MOF crystal structure, can be efficiently converted to mechanical energy to create a highly responsive, reversible, and selective sensor. This sensor responds to water, methanol, and ethanol vapors, but yields no response to either N{sub 2} or O{sub 2}. The magnitude of the signal, which is measured by a built-in piezoresistor, is correlated with the concentration and can be fitted to a Langmuir isotherm. Furthermore, we show that the hydration state of the MOF layer can be used to impart selectivity to CO{sub 2}. We also report the first use of surface-enhanced Raman spectroscopy to characterize the structure of a MOF film. We conclude that the synthetic versatility of these nanoporous materials holds great promise for creating recognition chemistries to enable selective detection of a wide range of analytes. A force field model is described that successfully predicts changes in MOF properties and the uptake of gases. This model is used to predict adsorption isotherms for a number of representative compounds, including explosives, nerve agents, volatile organic compounds, and polyaromatic hydrocarbons. The results show that, as a result of relatively large heats of adsorption (> 20 kcal mol{sup -1}) in most cases, we expect an onset of adsorption by MOF as low as 10{sup -6} kPa, suggesting the potential to detect compounds such as RDX at levels as low as 10 ppb at atmospheric pressure.

  5. Epitaxial Oxide Thin Films Grown by Solid Source Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Lu, Zihong

    1995-01-01

    The conventional liquid source metal-organic chemical vapor deposition (MOCVD) technique is capable of producing large area, high quality, single crystal semiconductor films. However, the growth of complex oxide films by this method has been hampered by a lack of suitable source materials. While chemists have been actively searching for new source materials, the research work reported here has demonstrated the successful application of solid metal-organic sources (based on tetramethylheptanedionate) to the growth of high quality thin films of binary compound cerium dioxide (CeO_2), and two more complex materials, the ternary compound lithium niobate (LiNbO_3), with two cations, and the quaternary compound strontium barium niobate (SBN), with three cations. The growth of CeO_2 thin films on (1012)Al_2O_3 substrates has been used as a model to study the general growth behavior of oxides. Factors affecting deposition rate, surface morphology, out-of-plane mosaic structure, and film orientation have been carefully investigated. A kinetic model based on gas phase prereaction is proposed to account for the substrate temperature dependence of film orientation found in this system. Atomically smooth, single crystal quality cerium dioxide thin films have been obtained. Superconducting YBCO films sputtered on top of solid source MOCVD grown thin cerium dioxide buffer layers on sapphire have been shown to have physical properties as good as those of YBCO films grown on single crystal MgO substrates. The thin film growth of LiNbO_3 and Sr_{1-x}Ba _{x}Nb_2 O_6 (SBN) was more complex and challenging. Phase purity, transparency, in-plane orientation, and the ferroelectric polarity of LiNbO _3 films grown on sapphire substrates was investigated. The first optical quality, MOCVD grown LiNbO _3 films, having waveguiding losses of less than 2 dB/cm, were prepared. An important aspect of the SBN film growth studies involved finding a suitable single crystal substrate material. Mg

  6. Heme-Containing Metal-Organic Frameworks for the Oxidative Degradation of Chemical Warfare Agents

    Science.gov (United States)

    2016-04-14

    P.O. Box 12211 Research Triangle Park, NC 27709-2211 metal-organic frameworks, catalysis , metalloporphyrins, oxidation chemistry REPORT DOCUMENTATION...respectively; hydrogen atoms are omitted for clarity. ARO Final Progress Report...red, gray, bright green, and dark green represent Fe, N, O, C, F, and Cl respectively; hydrogen atoms omitted from clarity. Right: Diffuse

  7. Soluble organic carbon and pH of organic amendments affect metal mobility and chemical speciation in mine soils.

    Science.gov (United States)

    Pérez-Esteban, Javier; Escolástico, Consuelo; Masaguer, Alberto; Vargas, Carmen; Moliner, Ana

    2014-05-01

    We evaluated the effects of pH and soluble organic carbon affected by organic amendments on metal mobility to find out the optimal conditions for their application in the stabilization of metals in mine soils. Soil samples (pH 5.5-6.2) were mixed with 0, 30 and 60 th a(-1) of sheep-horse manure (pH 9.4) and pine bark compost (pH 5.7). A single-step extraction procedure was performed using 0.005 M CaCl2 adjusted to pH 4.0-7.0 and metal speciation in soil solution was simulated using NICA-Donnan model. Sheep-horse manure reduced exchangeable metal concentrations (up to 71% Cu, 75% Zn) due to its high pH and degree of maturity, whereas pine bark increased them (32% Cu, 33% Zn). However, at increasing dose and hence pH, sheep-horse manure increased soluble Cu because of higher soluble organic carbon, whereas soluble Cu and organic carbon increased at increasing dose and correspondingly decreasing pH in pine bark and non-amended treatments. Near the native pH of these soils (at pH 5.8-6.3), with small doses of amendments, there was minimum soluble Cu and organic carbon. Pine bark also increased Zn solubility, whereas sheep-horse manure reduced it as soluble Zn always decreased with increasing pH. Sheep-horse manure also reduced the proportion of free metals in soil solution (from 41% to 4% Cu, from 97% to 94% Zn), which are considered to be more bioavailable than organic species. Sheep-horse manure amendment could be efficiently used for the stabilization of metals with low risk of leaching to groundwater at low doses and at relatively low pH, such as the native pH of mine soils. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Redox Active Transition Metal ions Make Melanin Susceptible to Chemical Degradation Induced by Organic Peroxide.

    Science.gov (United States)

    Zadlo, Andrzej; Pilat, Anna; Sarna, Michal; Pawlak, Anna; Sarna, Tadeusz

    2017-12-01

    With aging, retinal pigment epithelium melanosomes, by fusion with the age pigment lipofuscin, form complex granules called melanolipofuscin. Lipofuscin granules may contain oxidized proteins and lipid hydroperoxides, which in melanolipofuscin could chemically modify melanin polymer, while transition metal ions present in melanin can accelerate such oxidative modifications. The aim of this research was to examine the effect of selected transition metal ions on melanin susceptibility to chemical modification induced by the water-soluble tert-butyl hydroperoxide used as an oxidizing agent. Synthetic melanin obtained by DOPA autooxidation and melanosomes isolated from bovine retinal pigment epithelium were analyzed. To monitor tert-butyl hydroperoxide-induced oxidative changes of DMa and BMs, electron paramagnetic resonance spectroscopy, UV-vis absorption spectroscopy, dynamic light scattering, atomic force microscopy and electron paramagnetic resonance oximetry were employed. These measurements revealed that both copper and iron ions accelerated chemical degradation induced by tert-butyl hydroperoxide, while zinc ions had no effect. Strong prooxidant action was detected only in the case of melanosomes and melanin degraded in the presence of iron. It can be postulated that similar chemical processes, if they occur in situ in melanolipofuscin granules of the human retinal pigment epithelium, would modify antioxidant properties of melanin and its reactivity.

  9. Tuning of electrical and structural properties of indium oxide films grown by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Wang, Ch.Y.; Cimalla, V.; Romanus, H.; Kups, Th.; Niebelschuetz, M.; Ambacher, O.

    2007-01-01

    Tuning of structural and electrical properties of indium oxide (In 2 O 3 ) films by means of metal organic chemical vapor deposition is demonstrated. Phase selective growth of rhombohedral In 2 O 3 (0001) and body-centered cubic In 2 O 3 (001) polytypes on (0001) sapphire substrates was obtained by adjusting the substrate temperature and trimethylindium flow rate. The specific resistance of the as-grown films can be tuned by about two orders of magnitude by varying the growth conditions

  10. Metal-organic chemical vapor deposition enabling all-solid-state Li-ion microbatteries:a short review

    OpenAIRE

    Chen, C; Eichel, R-A; Notten, PHL Peter

    2017-01-01

    For powering small-sized electronic devices, all-solid-state Li-ion batteries are the most promising candidates due to its safety and allowing miniaturization. Thin film deposition methods can be used for building new all-solid-state architectures. Well-known deposition methods are sputter deposition, pulsed laser deposition, sol-gel deposition, atomic layer deposition, etc. This review summarizes thin film storage materials deposited by metal-organic chemical vapor deposition (MOCVD) for all...

  11. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Dutta, P.; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V.; Zheng, N.; Ahrenkiel, P.; Martinez, J.

    2014-01-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10 7  cm −2 . Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm 2 /V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  12. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    Science.gov (United States)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  13. Chemical reactions of metal powders with organic and inorganic liquids during ball milling

    Science.gov (United States)

    Arias, A.

    1975-01-01

    Chromium and/or nickel powders were milled in metal chlorides and in organic liquids representative of various functional groups. The powders always reacted with the liquid and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 weight percent. Compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid.

  14. Luminescent lanthanide metal-organic frameworks for chemical sensing and toxic anion detection.

    Science.gov (United States)

    Wu, Rui-Zhi; Yang, Xing; Zhang, Liang-Wei; Zhou, Pan-Pan

    2017-08-01

    Prototype lanthanide metal-organic frameworks (LnMOFs), Ln(BTC) (Ln = Eu and Tb; BTC = benzene-1,3,5-tricarboxylate), have been considered as luminescent sensors for detecting toxic anions, while their neutral pore structures have limited the entrance and encapsulation of anions to produce highly anion-responsive photoluminescence (PL). To facilitate anions to enter the pore space of Ln(BTC), a one-pot synthesis method was proposed in which BTC was partially replaced with its structural analogue L·BF 4 (H 3 L·BF 4 = 2,4,6-tricarboxy-1-methylpyridinium tetrafluoroborate) which consists of an anion affinity site of cationic methylpyridinium. Compared to the original Ln(BTC), the co-doped cationic framework Eu 0.05 Tb 0.95 -BTC 0.9 L 0.1 is highly sensitive for detecting different toxic anions by tuning the energy absorption of organic chromophores, the energy transfer efficiency to Ln 3+ ions and the energy allocation between different Ln 3+ ions in the PL spectra. We demonstrated that the Eu 0.05 Tb 0.95 -BTC 0.9 L 0.1 PL sensor has the capability of decoding various toxic anions with a clearly differentiable and unique emission intensity ratio of 5 D 4 → 7 F 5 (Tb 3+ , 545 nm) to 5 D 0 → 7 F 2 (Eu 3+ , 618 nm) transitions (I Tb /I Eu ). Compared to Ln(BTC), the co-doped Eu 0.05 Tb 0.95 -BTC 0.9 L 0.1 presents self-calibrating, high distinguishable and stable PL signals for detecting toxic anions.

  15. Natural radioactivity levels and heavy metals in chemical and organic fertilizers used in Kingdom of Saudi Arabia.

    Science.gov (United States)

    El-Taher, A; Althoyaib, S S

    2012-01-01

    The present work deals with identifying and determining the activity levels of natural occuring radionuclides, (226)Ra and (232)Th series, their decay products and (40)K, in chemical and organic fertilizers used in Kingdom of Saudi Arabia. A total of 30 samples: 20 phosphatic fertilizers (single super-phosphate SSP and triple super-phosphate,TSP) and 10 organic fertilizers (cow, sheep and chicken) collected from markets and farms. The gamma-ray spectrometer consists of NaI(Tl) detector and its electronic circuit was used for measuring γ-ray spectra. The ranges of radioactivity levels of (226)Ra, (232)Th and (40)K in chemical fertilizers are 51.5±5.2-106.3±7.5, 5.1±1.6-9.9±3.2. and 462.6±21-607.3±14Bqkg(-1), respectively. The activities of (226)Ra, (232)Th and (40)K in natural fertilizers (cow, sheep and chicken) are lower than the activities in chemical fertilizers. The obtained data are compared with available reported data from other countries in literature. The Ra(eq) in chemical fertilizer ranges from 100.37 to 161.43Bqkg(-1) and in organic fertilizer ranges from 34.07 to 102.19Bqkg(-1), which are lower than the limit of 370Bqkg(-1) adopted from NEA-OECD (1979). The average heavy metal (Pb, Cd, Ni, Co and Cr) contents of the fertilizers marketed in the Kingdom of Saudi Arabia are also determined and within the limits of those used worldwide. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, P., E-mail: pdutta2@central.uh.edu; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V. [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Zheng, N.; Ahrenkiel, P. [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States); Martinez, J. [Materials Evaluation Laboratory, NASA Johnson Space Center, Houston, Texas 77085 (United States)

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  17. Lanthanide-Functionalized Metal-Organic Framework Hybrid Systems To Create Multiple Luminescent Centers for Chemical Sensing.

    Science.gov (United States)

    Yan, Bing

    2017-11-21

    Metal-organic frameworks (MOFs) possess an important advantage over other candidate classes for chemosensory materials because of their exceptional structural tunability and properties. Luminescent sensing using MOFs is a simple, intuitive, and convenient method to recognize species, but the method has limitations, such as insufficient chemical selectivity and signal loss. MOFs contain versatile building blocks (linkers or ligands) with special chemical reactivity, and postsynthetic modification (PSM) provides an opportunity to exploit and expand their unique properties. The linkers in most MOFs contain aromatic subunits that can readily display luminescence after ultraviolet or visible (typically blue) excitation, and this is the main luminescent nature of most MOFs. The introduction of photoactive lanthanide ions (Ln 3+ ) into the MOF hosts may produce new luminescent signals at different positions from that of the MOF linker, but this depends on the intramolecular energy transfer (antenna effect) from the MOF (linkers) to the Ln 3+ ions. Controlling the Ln 3+ content in MOF hybrids may create multiple luminescent centers. The nature of the unique luminescent centers may cause different responses to sensing species (i.e., ratiometric sensing), which may provide a new opportunity for luminescence research with applications to chemical sensing. In this Account, recent research progress on using lanthanide-functionalized MOF hybrid materials to create multiple luminescent centers for chemical sensing is described. Here we propose a general strategy to functionalize MOF hosts with lanthanide ions, compounds, or other luminescent species (organic dyes or carbon dots) and to assemble types of photofunctional hybrid systems based on lanthanide-functionalized MOFs. Five main methods were used to functionalize the MOFs and assemble the hybrid materials: in situ composition, ionic doping, ionic exchange, covalent PSM, and coordinated PSM. Through the lanthanide

  18. InAs/GaSb core-shell nanowires grown on Si substrates by metal-organic chemical vapor deposition

    Science.gov (United States)

    Ji, Xianghai; Yang, Xiaoguang; Du, Wenna; Pan, Huayong; Luo, Shuai; Ji, Haiming; Xu, Hongqi; Yang, Tao

    2017-06-01

    We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition (MOCVD) with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core without any misfit dislocations.

  19. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO3 films

    International Nuclear Information System (INIS)

    Rozier, Y.; Gautier, B.; Hyvert, G.; Descamps, A.; Plossu, C.; Dubourdieu, C.; Ducroquet, F.

    2009-01-01

    The properties of SrTiO 3 thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO 2 , using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers

  20. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Rozier, Y. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France); Gautier, B. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France)], E-mail: bgautier@insa-lyon.fr; Hyvert, G.; Descamps, A.; Plossu, C. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France); Dubourdieu, C. [Laboratoire des Materiaux et du Genie Physique (LMGP), CNRS, INPG, 3 parvis L. Neel, BP 257, 38016 Grenoble Cedex 1 (France); Ducroquet, F. [Institut de Microelectronique, Electromagnetisme et Photonique (IMEP), 3, rue Parvis Louis Neel BP 257, 38016 GRENOBLE Cedex 1 (France)

    2009-01-30

    The properties of SrTiO{sub 3} thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO{sub 2}, using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers.

  1. Co3O4 protective coatings prepared by Pulsed Injection Metal Organic Chemical Vapour Deposition

    DEFF Research Database (Denmark)

    Burriel, M.; Garcia, G.; Santiso, J.

    2005-01-01

    of deposition temperature. Pure Co3O4 spinel structure was found for deposition temperatures ranging from 360 to 540 degreesC. The optimum experimental parameters to prepare dense layers with a high growth rate were determined and used to prepare corrosion protective coatings for Fe-22Cr metallic interconnects...

  2. A Chemical Role for Trichloromethane: Room-Temperature Removal of Coordinated Solvents from Open Metal Sites in the Copper-Based Metal-Organic Frameworks.

    Science.gov (United States)

    Choi, Jae Sun; Bae, Jinhee; Lee, Eun Ji; Jeong, Nak Cheon

    2018-04-17

    Open coordination sites (OCSs) in metal-organic frameworks (MOFs) have shown potential in applications such as molecular separation, sorption, catalysis, and sensing. Thus, the removal of coordinated solvent has been viewed as an essential step that needs to be performed prior to the use of the MOFs in the above applications. To date, a thermal method that is normally performed by applying heat and vacuum has been the most commonly employed activation method despite its negative influence on the structural integrity of the MOFs. In this report, we demonstrate that commonly inert trichloromethane (TCM) can activate OCSs; the TCM treatment process serves as an alternative chemical route to activation that does not require the external thermal energy. On the basis of the Raman study, we suggest a possible mechanism for the chemical activation process where TCM may weakly coordinate to the OCSs and then spontaneously dissociate. In addition, we prove that the chemical activation behavior is substantially boosted when a small amount of external heat energy (55 °C, 2.6 meV) is supplied during the TCM treatment. Using an HKUST-1-polyvinylidene fluoride (PVDF) mixed matrix (MM), we also demonstrate that this chemical activation strategy is a safe way to activate thermally deformable MOF-polymer mixed matrices.

  3. Impregnated Metal-Organic Frameworks for the Removal of Toxic Industrial Chemicals

    Science.gov (United States)

    2008-11-01

    enhance reactivity towards toxic chemicals. Typical impregnations of current materials, such as ASZM-TEDA, are done in an aqueous and/or ammoniacal ...ammonium hydroxide/ammonium carbonate/water solution (referred to as ammoniacal solution). Clearly, this solution would not be suitable for impregnation

  4. Metal organic chemical vapor deposition of 111-v compounds on silicon

    Science.gov (United States)

    Vernon, Stanley M.

    1986-01-01

    Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

  5. Fabrication of single-phase ε-GaSe films on Si(100) substrate by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Chang, Chia-Chen; Zeng, Jia-Xian; Lan, Shan-Ming; Uen, Wu-Yih; Liao, Sen-Mao; Yang, Tsun-Neng; Ma, Wei-Yang; Chang, Kuo-Jen

    2013-01-01

    Single-phase ε-gallium selenide (GaSe) films were fabricated on Si(100) substrate by metal organic chemical vapor deposition using dual-source precursors: triethylgallium (TEG) and hydrogen selenide (H 2 Se) with the flow ratio of [H 2 Se]/[TEG] being maintained at 1.2. In particular, an arsine (AsH 3 ) flow was introduced to the Si substrate before the film deposition to induce an arsenic (As)-passivation effect on the substrate. The crystalline structure of GaSe films prepared was analyzed using X-ray diffraction and the surface morphology of them was characterized by scanning electron microscopy. It was found that the film quality could be improved by the As-passivation effect. The optical properties of the films were studied by temperature dependent photoluminescence (PL) measurements. PL spectra obtained with different distributions and intensities favored for resolving the superior material quality of the films produced on the substrate with As-passivation compared to those produced on the substrate without As-passivation. The former was dominated by the excitonic emissions for the whole temperature range of 20–300 K examined, while the latter was initially dominated by the defect-related emission at 1.907 eV for a low-temperature range ≦ 80 K and then became dominated by the weak excitonic emission band instead. The ε modification of GaSe films prepared was further recognized by the Raman scattering measurements conducted at room temperature. - Highlights: • Gallium selenide (GaSe) layered structures are fabricated on Si(100) substrate. • Metal–organic chemical vapor deposition is used for film fabrication. • Arsenic-passivation effects of Si substrate on the GaSe film quality are analyzed. • Photoluminescence measurements of GaSe polycrystals are reported

  6. Metal organic chemical vapor deposition of superconducting YBa2Cu3O7-x thin films

    Science.gov (United States)

    Zawadzki, P. A.; Tompa, G. S.; Norris, P. E.; Chern, C. S.; Caracciolo, R.; Kear, B. H.; Noh, D. W.; Gallois, B.

    1990-04-01

    The discovery of YBCO superconductors has stimulated a great deal of scientific and technological research into thin films of these materials. Because the MOCVD technique is known to produce high quality films in the III/V and II/VI material groups, our approach has been to apply the method to superconducting thin films. Thin films were grown in a vertical high speed (0 2000 rpm) rotating disk reactor. The source materials were metal β-diketonates kept at temperatures in excess of 100° in order to obtain growth rates of 0.3 to 0.5 μm/hr. The precursors were transported to the chamber with a nitrogen carrier and injected separately in order to avoid any gas phase reactions. The chamber pressure was maintained at 76 Torr with an oxygen partial pressure of 38 Torr. A resistance heater was used to keep the substrate temperature at 500° YBa2Cu3O7- x films were deposited simultaneously on a variety of substrates such as (100) MgO, (1-102) sapphire, (100) SrTiO3 and (100) YSZ. Full XPS spectra were collected for the binary oxides. The scans demonstrate the existence of Y2O3, BaO, and CuO with the correct valence state for the metallic species. Energy dispersive analysis of x-ray (EDAX) was used to determine film compositions by comparing EDAX spectral intensity to a known superconducting standard. Appropriate changes were made in the precursor flows to correct the stoichiometry. The as-grown films were dark brown and semi-transparent. Cross-sectional SEM photomicrographs revealed an ordered columnar structure. After annealing at 950 980° however, the films on (100) SrTiO3 appeared dull black and opaque. The surface morphology exhibited smooth large plate-like grains. X-ray data clearly display an orthorhombic phase, with c-axis perpendicular to the substrate surface. Four point resistance measurements for films on (100) SrTiO3 show the onset of superconductivity at 90 K with a complete loss of resistance at 88 K. This sharp (≤2K) transition shows the high quality

  7. The protective properties of thin alumina films deposited by metal organic chemical vapour deposition against high-temperature corrosion of stainless steels

    NARCIS (Netherlands)

    Morssinkhof, R.W.J.; Fransen, T.; Heusinkveld, M.M.D.; Gellings, P.J.

    1989-01-01

    Coatings of Al2O3 were deposited on Incoloy 800H and AISI 304 by means of metal organic chemical vapour deposition. Diffusion limitation was the rate-determining step above 420 °C. Below this temperature, the activation energy of the reaction appeared to be 30 kJ mol−1. Coating with Al2O3 increases

  8. Properties of alumina films prepared by metal-organic chemical vapour deposition at atmospheric pressure in hte presence of small amounts of water

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Rem, J.B.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin alumina films were deposited on stainless steel, type AISI 304. The deposition process was carried out in nitrogen with low partial pressures of water (0–2.6 × 10−2 kPa (0−0.20 mmHg)) by metal-organic chemical vapour deposition (MOCVD) with aluminium-tri-sec-butoxide (ATSB) as the precursor.

  9. Characterization of TiO2 thin films obtained by metal-organic chemical vapour deposition

    International Nuclear Information System (INIS)

    Carriel, Rodrigo Crociati

    2015-01-01

    Titanium dioxide (TiO 2 ) thin films were grown on silicon substrate (100) by MOCVD process (chemical deposition of organometallic vapor phase). The films were grown at 400, 500, 600 and 700 ° C in a conventional horizontal equipment. Titanium tetraisopropoxide was used as source of both oxygen and titanium. Nitrogen was used as carrier and purge gas. X-ray diffraction technique was used for the characterization of the crystalline structure. Scanning electron microscopy with field emission gun was used to evaluate the morphology and thickness of the films. The films grown at 400 and 500°C presented anatase phase. The film grown at 600ºC presented rutile besides anatase phase, while the film grown at 700°C showed, in addition to anatase and rutile, brookite phase. In order to evaluate the electrochemical behavior of the films cyclic voltammetry technique was used. The tests revealed that the TiO2 films formed exclusively by the anatase phase exhibit strong capacitive character. The anodic current peak is directly proportional to the square root of the scanning rate for films grown at 500ºC, suggesting that linear diffusion is the predominant mechanism of cations transport. It was observed that in the film grown during 60 minutes the Na+ ions intercalation and deintercalation easily. The films grown in the other conditions did not present the anodic current peak, although charge was accumulated in the film. (author)

  10. Metal-organic chemical vapour deposition of lithium manganese oxide thin films via single solid source precursor

    Directory of Open Access Journals (Sweden)

    Oyedotun K.O.

    2015-12-01

    Full Text Available Lithium manganese oxide thin films were deposited on sodalime glass substrates by metal organic chemical vapour deposition (MOCVD technique. The films were prepared by pyrolysis of lithium manganese acetylacetonate precursor at a temperature of 420 °C with a flow rate of 2.5 dm3/min for two-hour deposition period. Rutherford backscattering spectroscopy (RBS, UV-Vis spectrophotometry, X-ray diffraction (XRD spectroscopy, atomic force microscopy (AFM and van der Pauw four point probe method were used for characterizations of the film samples. RBS studies of the films revealed fair thickness of 1112.311 (1015 atoms/cm2 and effective stoichiometric relationship of Li0.47Mn0.27O0.26. The films exhibited relatively high transmission (50 % T in the visible and NIR range, with the bandgap energy of 2.55 eV. Broad and diffused X-ray diffraction patterns obtained showed that the film was amorphous in nature, while microstructural studies indicated dense and uniformly distributed layer across the substrate. Resistivity value of 4.9 Ω·cm was obtained for the thin film. Compared with Mn0.2O0.8 thin film, a significant lattice absorption edge shift was observed in the Li0.47Mn0.27O0.26 film.

  11. Metal-Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform.

    Science.gov (United States)

    Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T; Ohodnicki, Paul R

    2018-02-23

    Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal-organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability of MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2 , N 2 , O 2 , and CO) with rapid (optical fiber platform which results in an amplification of inherent optical absorption present within the MOF-based sensing layer with increasing values of effective refractive index associated with adsorption of gases.

  12. In Situ Probes of Capture and Decomposition of Chemical Warfare Agent Simulants by Zr-Based Metal Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Plonka, Anna M.; Wang, Qi; Gordon, Wesley O.; Balboa, Alex; Troya, Diego; Guo, Weiwei; Sharp, Conor H.; Senanayake, Sanjaya D.; Morris, John R.; Hill, Craig L.; Frenkel, Anatoly I. (BNL); (Virginia Tech); (ECBC); (Emory); (SBU)

    2017-01-18

    Zr-based metal organic frameworks (MOFs) have been recently shown to be among the fastest catalysts of nerve-agent hydrolysis in solution. We report a detailed study of the adsorption and decomposition of a nerve-agent simulant, dimethyl methylphosphonate (DMMP), on UiO-66, UiO-67, MOF-808, and NU-1000 using synchrotron-based X-ray powder diffraction, X-ray absorption, and infrared spectroscopy, which reveals key aspects of the reaction mechanism. The diffraction measurements indicate that all four MOFs adsorb DMMP (introduced at atmospheric pressures through a flow of helium or air) within the pore space. In addition, the combination of X-ray absorption and infrared spectra suggests direct coordination of DMMP to the Zr6 cores of all MOFs, which ultimately leads to decomposition to phosphonate products. These experimental probes into the mechanism of adsorption and decomposition of chemical warfare agent simulants on Zr-based MOFs open new opportunities in rational design of new and superior decontamination materials.

  13. Influences of ultrathin amorphous buffer layers on GaAs/Si grown by metal-organic chemical vapor deposition

    Science.gov (United States)

    Hu, Haiyang; Wang, Jun; Cheng, Zhuo; Yang, Zeyuan; Yin, Haiying; Fan, Yibing; Ma, Xing; Huang, Yongqing; Ren, Xiaomin

    2018-04-01

    In this work, a technique for the growth of GaAs epilayers on Si, combining an ultrathin amorphous Si buffer layer and a three-step growth method, has been developed to achieve high crystalline quality for monolithic integration. The influences of the combined technique for the crystalline quality of GaAs on Si are researched in this article. The crystalline quality of GaAs epilayer on Si with the combined technique is investigated by scanning electron microscopy, double crystal X-ray diffraction (DCXRD), photoluminescence, and transmission electron microscopy measurements. By means of this technique, a 1.8-µm-thick high-quality GaAs/Si epilayer was grown by metal-organic chemical vapor deposition. The full-width at half-maximum of the DCXRD rocking curve in the (400) reflection obtained from the GaAs/Si epilayers is about 163 arcsec. Compared with only using three-step growth method, the current technique reduces etch pit density from 3 × 106 cm-2 to 1.5 × 105 cm-2. The results demonstrate that the combined technique is an effective approach for reducing dislocation density in GaAs epilayers on Si.

  14. Effects of deposition temperature and ammonia flow on metal-organic chemical vapor deposition of hexagonal boron nitride

    Science.gov (United States)

    Rice, Anthony; Allerman, Andrew; Crawford, Mary; Beechem, Thomas; Ohta, Taisuke; Spataru, Catalin; Figiel, Jeffrey; Smith, Michael

    2018-03-01

    The use of metal-organic chemical vapor deposition at high temperature is investigated as a means to produce epitaxial hexagonal boron nitride (hBN) at the wafer scale. Several categories of hBN films were found to exist based upon precursor flows and deposition temperature. Low, intermediate, and high NH3 flow regimes were found to lead to fundamentally different deposition behaviors. The low NH3 flow regimes yielded discolored films of boron sub-nitride. The intermediate NH3 flow regime yielded stoichiometric films that could be deposited as thick films. The high NH3 flow regime yielded self-limited deposition with thicknesses limited to a few mono-layers. A Langmuir-Hinshelwood mechanism is proposed to explain the onset of self-limited behavior for the high NH3 flow regime. Photoluminescence characterization determined that the intermediate and high NH3 flow regimes could be further divided into low and high temperature behaviors with a boundary at 1500 °C. Films deposited with both high NH3 flow and high temperature exhibited room temperature free exciton emission at 210 nm and 215.9 nm.

  15. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  16. Behavior and impact of sulfur incorporation in Zinc Oxysulfide alloy grown by metal organic chemical vapor deposition

    Science.gov (United States)

    Ma, Jingrui; Tang, Kun; Mao, Haoyuan; Ye, Jiandong; Zhu, Shunming; Xu, Zhonghua; Yao, Zhengrong; Gu, Shulin; Zheng, Youdou

    2018-03-01

    Highly mismatched ZnO1-xSx:N alloy films with various x were deposited on c-plane sapphire substrates by a near-equilibrium method, metal-organic chemical vapor deposition. The sulfur concentration in the films could be tuned by changing the flow rate of H2S during the growth process. The films that could maintain single phase have an upper limit for x ∼ 0.15, which is smaller than the x values obtained from other non-equilibrium-grown samples (x ∼ 0.23). When x > 0.15, phases other than the wurtzite ZnO (W-ZnO) one appeared. Those phases were ascribed to the sulfur-diluted W-ZnO like phase, low x W-ZnO like phase, and high x W-ZnS like phase. The S contents in different phase has been determined by using Vegard's law and the X-ray photoelectron spectroscopy. Meanwhile, the compositional dependence of the bandgap energy in the ZnO1-xSx alloyed material has been investigated and studied comparing with other reported results. The dispersed bowing parameter b and the mechanism of the phase separation in samples grown by both the near-equilibrium method and the non-equilibrium one have also been discussed based on the difference of the atomic radius and electronegativity of the oxygen and sulfur atoms. Furthermore, the Raman and photoluminescence spectra have shown that the sulfur incorporation may suppress zinc interstitials related defects, while the oxygen vacancies related defects may be easily formed at the same time. These results indicate that ZnO1-xSx films could be beneficial to the realization of p-type doping in ZnO, although no obvious p-type characteristic has been attained in the work yet.

  17. Metal Organic Framework

    Indian Academy of Sciences (India)

    IAS Admin

    X-ray crystallography is the most comprehensive character- ization tool to gain a molecular level understanding of a range of crystalline materials. One of the recent areas in which research with the aid of crystallography has exploded, is the metal organic frameworks (MOFs). These are porous crystal- line solids with ...

  18. Metal Organic Frameworks (MOFs)

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 11. Molecule Matters - Metal Organic Frameworks (MOFs). R Sarvanakumar S Sankararaman. Feature Article Volume 12 Issue 11 November 2007 pp 77-86. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. A New Class of Metal-Cyclam-Based Zirconium Metal–Organic Frameworks for CO 2 Adsorption and Chemical Fixation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jie [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Usov, Pavel M. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Xu, Wenqian [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS) and X-ray Science Division; Celis-Salazar, Paula J. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Lin, Shaoyang [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Kessinger, Matthew C. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Landaverde-Alvarado, Carlos [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemical Engineering and Macromolecules Innovation Inst.; Cai, Meng [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; May, Ann M. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Slebodnick, Carla [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry; Zhu, Dunru [Nanjing Univ. of Technology (China). State Key Lab. of Materials-Oriented Chemical Engineering (MCE) and College of Chemical Engineering; Senanayake, Sanjaya D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Chemistry; Morris, Amanda J. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Chemistry and Macromolecules Innovation Inst.

    2017-12-22

    Metal-organic frameworks (MOFs) have shown great promise in catalysis, mainly due to their high content of active centers, large internal surface areas, tunable pore size, and versatile chemical functionalities. However, it is a challenge to rationally design and construct MOFs that can serve as highly stable and reusable heterogeneous catalysts. Here two new robust 3D porous metal-cyclam-based zirconium MOFs, denoted VPI-100 (Cu) and VPI-100 (Ni), have been prepared by a modulated synthetic strategy. The frameworks are assembled by eight-connected Zr-6 clusters and metallocyclams as organic linkers. Importantly, the cyclam core has accessible axial coordination sites for guest interactions and maintains the electronic properties exhibited by the parent cyclam ring. The VPI-100 MOFs exhibit excellent chemical stability in various organic and aqueous solvents over a wide pH range and show high CO2 uptake capacity (up to similar to 9.83 wt% adsorption at 273 K under 1 atm). Moreover, VPI-100 MOFs demonstrate some of the highest reported catalytic activity values (turnover frequency and conversion efficiency) among Zr-based MOFs for the chemical fixation of CO2 with epoxides, including sterically hindered epoxides. The MOFs, which bear dual catalytic sites (Zr and Cu/Ni), enable chemistry not possible with the cyclam ligand under the same conditions and can be used as recoverable stable heterogeneous catalysts without losing performance.

  20. Chemical contaminants (trace metals, persistent organic pollutants) in albacore tuna from western Indian and south-eastern Atlantic Oceans: Trophic influence and potential as tracers of populations.

    Science.gov (United States)

    Chouvelon, Tiphaine; Brach-Papa, Christophe; Auger, Dominique; Bodin, Nathalie; Bruzac, Sandrine; Crochet, Sylvette; Degroote, Maxime; Hollanda, Stephanie J; Hubert, Clarisse; Knoery, Joël; Munschy, Catherine; Puech, Alexis; Rozuel, Emmanuelle; Thomas, Bastien; West, Wendy; Bourjea, Jérôme; Nikolic, Natacha

    2017-10-15

    Albacore tuna (Thunnus alalunga) is a highly commercial fish species harvested in the world's Oceans. Identifying the potential links between populations is one of the key tools that can improve the current management across fisheries areas. In addition to characterising populations' contamination state, chemical compounds can help refine foraging areas, individual flows and populations' structure, especially when combined with other intrinsic biogeochemical (trophic) markers such as carbon and nitrogen stable isotopes. This study investigated the bioaccumulation of seven selected trace metals - chromium, nickel, copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg) and lead - in the muscle of 443 albacore tunas, collected over two seasons and/or years in the western Indian Ocean (WIO: Reunion Island and Seychelles) and in the south-eastern Atlantic Ocean (SEAO: South Africa). The main factor that explained metal concentration variability was the geographic origin of fish, rather than the size and the sex of individuals, or the season/year of sampling. The elements Cu, Zn, Cd and Hg indicated a segregation of the geographic groups most clearly. For similar sized-individuals, tunas from SEAO had significantly higher concentrations in Cu, Zn and Cd, but lower Hg concentrations than those from WIO. Information inferred from the analysis of trophic markers (δ 13 C, δ 15 N) and selected persistent organic pollutants, as well as information on stomach contents, corroborated the geographical differences obtained by trace metals. It also highlighted the influence of trophic ecology on metal bioaccumulation. Finally, this study evidenced the potential of metals and chemical contaminants in general as tracers, by segregating groups of individuals using different food webs or habitats, to better understand spatial connectivity at the population scale. Limited flows of individuals between the SEAO and the WIO are suggested. Albacore as predatory fish also provided some

  1. Liquid Membranes as a Tool for Chemical Speciation of Metals in Natural Waters: Organic and Inorganic Complexes of Nickel.

    Science.gov (United States)

    Vergel, Cristina; Mendiguchía, Carolina; Moreno, Carlos

    2018-04-15

    The different species of nickel present in natural waters exhibit different transport behaviour through bulk liquid membranes (BLMs). This fact has been used to design and optimise a separation/pre-concentration system applicable to separate labile and non-labile nickel fractions. A hydrazone derivative-1,2-cyclohexanedione bis-benzoyl-hydrazone (1,2-CHBBH) dissolved in toluene/dimethyl formamide (2% DMF)-was used as a chemical carrier of nickel species, from an aqueous source solution (sample) to a receiving acidic solution. Both chemical and hydrodynamic conditions controlling the transport system were studied and optimised. Under optimum conditions, variations in the transport of nickel ions as a function of organic (humic acids) and inorganic (chloride ions) ligands were studied. Relationships between the permeability coefficient ( P ) or recovery efficiency (%R) and the concentrations of ligands and nickel species were analysed using Winhumic V software. A negative correlation between P and the concentration of organic nickel complexes was found, suggesting that only labile nickel species are transported through the liquid membrane, with non-labile complexes remaining in the water sample; allowing for their separation and subsequent quantification in natural waters.

  2. Influence of vicinal sapphire substrate on the properties of N-polar GaN films grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhiyu; Zhang, Jincheng, E-mail: jchzhang@xidian.edu.cn; Xu, Shengrui; Chen, Zhibin; Yang, Shuangyong; Tian, Kun; Hao, Yue [Key Lab of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi' an, Shaanxi 710071 (China); Su, Xujun [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123 (China); Shi, Xuefang [School of Advanced Materials and Nanotechnology, Xidian University, Xi' an, Shaanxi 710071 (China)

    2014-08-25

    The influence of vicinal sapphire substrates on the growth of N-polar GaN films by metal-organic chemical vapor deposition is investigated. Smooth GaN films without hexagonal surface feature are obtained on vicinal substrate. Transmission electron microscope results reveal that basal-plane stacking faults are formed in GaN on vicinal substrate, leading to a reduction in threading dislocation density. Furthermore, it has been found that there is a weaker yellow luminescence in GaN on vicinal substrate than that on (0001) substrate, which might be explained by the different trends of the carbon impurity incorporation.

  3. High-voltage vertical GaN Schottky diode enabled by low-carbon metal-organic chemical vapor deposition growth

    Science.gov (United States)

    Cao, Y.; Chu, R.; Li, R.; Chen, M.; Chang, R.; Hughes, B.

    2016-02-01

    Vertical GaN Schottky barrier diode (SBD) structures were grown by metal-organic chemical vapor deposition on free-standing GaN substrates. The carbon doping effect on SBD performance was studied by adjusting the growth conditions and spanning the carbon doping concentration between ≤3 × 1015 cm-3 and 3 × 1019 cm-3. Using the optimized growth conditions that resulted in the lowest carbon incorporation, a vertical GaN SBD with a 6-μm drift layer was fabricated. A low turn-on voltage of 0.77 V with a breakdown voltage over 800 V was obtained from the device.

  4. Recycling of metal-organic chemical vapor deposition waste of GaN based power device and LED industry by acidic leaching: Process optimization and kinetics study

    Science.gov (United States)

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon; Park, Jeung-Jin

    2015-05-01

    Recovery of metal values from GaN, a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acidic leaching. Leaching kinetics of gallium rich MOCVD waste is studied and the process is optimized. The gallium rich waste MOCVD dust is characterized by XRD and ICP-AES analysis followed by aqua regia digestion. Different mineral acids are used to find out the best lixiviant for selective leaching of the gallium and indium. Concentrated HCl is relatively better lixiviant having reasonably faster kinetic and better leaching efficiency. Various leaching process parameters like effect of acidity, pulp density, temperature and concentration of catalyst on the leaching efficiency of gallium and indium are investigated. Reasonably, 4 M HCl, a pulp density of 50 g/L, 100 °C and stirring rate of 400 rpm are the effective optimum condition for quantitative leaching of gallium and indium.

  5. Chemical speciation of trace metals in seawater: a review.

    Science.gov (United States)

    Hirose, Katsumi

    2006-08-01

    The recent development of the chemical speciation of trace metals in seawater is described. The speciation studies reveal that metal ion complexation is one of the most important processes in seawater; especially, most bioactive trace metals, such as Fe(III) and Cu, exist as complexes with ligands in dissolved organic matter. The organic ligands in seawater are characterized with metal ions selected by the HSAB concept. A strong organic ligand, which originates from marine microorganisms, is classified as a hard base including carboxylates. The free organic ligand concentrations in seawater are buffered by complexation with excess amounts of Ca and Mg in seawater. The chemical equilibrium model suggested that the concentrations of bioactive free metal ions are at an optimal level to activities of marine microorganisms. For chemical speciation, it is important to have a better understanding of the ecological roles of trace metals in seawater.

  6. Organic Superconductor, Made without Metals.

    Science.gov (United States)

    Science News, 1980

    1980-01-01

    The discovery of a superconducting organic compound is reported. The compound, (TMTSF)-2, has no metal in its composition, and the author believes that it is the precursor of a family of superconducting organics. (Author/SA)

  7. Chemical behaviour of heavy metals and their bioavailability and toxicity to organisms: implications for environmental quality criteria

    CSIR Research Space (South Africa)

    Pretorius, PJ

    2001-09-01

    Full Text Available Observed mortalities of Daphnia pulex exposed to a single concentration of zinc in different test waters are explained in terms of the chemical behaviour of zinc in solution, as predicted by chemical speciation modelling. Multivariate correlation...

  8. Effect of chemical structure of S-nitrosothiols on nitric oxide release mediated by the copper sites of a metal organic framework based environment.

    Science.gov (United States)

    Taylor-Edinbyrd, Kiara; Li, Tanping; Kumar, Revati

    2017-05-17

    The effect of chemical structure of different biologically compatible S-nitrosothiols on the solvation environment at catalytic copper sites in a metal organic framework (MOF) suspended in a solution of ethanol is probed using computational methods. The use of a copper based MOF as a storage vehicle and catalyst (copper sites of the MOF) in the controlled and sustained release of chemically stored nitric oxide (NO) from S-nitrosocysteine has been shown to occur both experimentally and computationally [J. Am. Chem. Soc., 2012, 134, 3330-3333; Phys. Chem. Chem. Phys., 2015, 17, 23403]. Previous studies on a copper based MOF, namely HKUST-1, concluded that modifications in the R-group of s-nitrosothiols and/or organic linkers of MOFs led to a method capable of modulating NO release. In order to test the hypothesis that larger R-groups slow down NO release, four different RSNOs (R = cysteine, N-acetylcysteine, N-acetyl-d,l-penicillamine or glutathione) of varying size were investigated, which in turn required the use of a larger copper based MOF. Due to its desirable copper centers and more extensive framework, MOF-143, an analog of HKUST-1 was chosen to further explore both the effect of different RSNOs as well as MOF environments on NO release. Condensed phase classical molecular dynamics simulations are utilized to study the effect of the complex MOF environment as well as the chemical structure and size of the RSNO on the species on the catalytic reaction. The results indicate that in addition to the size of the RSNO species and the organic linkers within the MOF, the reaction rates can be modulated by the molecular structure of the RSNO and furthermore combining different RSNO species can also be used to tune the rate of NO release.

  9. Characterization of Pb(Zr, Ti)O sub 3 thin films prepared by metal-organic chemical-vapor deposition using a solid delivery system

    CERN Document Server

    Shin, J C; Hwang, C S; Kim, H J; Lee, J M

    1999-01-01

    Pb(Zr, Ti)O sub 3 (PZT) thin films were deposited on Pt/SiO sub 2 /Si substrates by metal-organic chemical-vapor deposition technique using a solid delivery system to improve the reproducibility of the deposition. The self-regulation mechanism, controlling the Pb-content of the film, was observed to work above a substrate temperature of 620 .deg. C. Even with the self-regulation mechanism, PZT films having low leakage current were obtained only when the molar mixing ratio of the input precursors was 1

  10. Fabrication of 100 A class, 1 m long coated conductor tapes by metal organic chemical vapor deposition and pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V.; Lee, H.G.; Li, Y.; Xiong, X.; Qiao, Y.; Reeves, J.; Xie, Y.; Knoll, A.; Lenseth, K

    2003-10-15

    SuperPower has been scaling up YBa{sub 2}Cu{sub 3}O{sub x}-based second-generation superconducting tapes by techniques such as pulsed laser deposition (PLD) using industrial laser and metal organic chemical vapor deposition (MOCVD). Both techniques offer advantage of high deposition rates, which is important for high throughput. Using highly-polished substrates produced in a reel-to-reel polishing facility and buffer layers deposited in a pilot ion beam assisted deposition facility, meter-long second-generation high temperature superconductor tapes have been produced. 100 A class, meter-long coated conductor tapes have been reproducibly demonstrated in this work by both MOCVD and PLD. The best results to date are 148 A over 1.06 m by MOCVD and 135 A over 1.1 m by PLD using industrial laser.

  11. Axial heterostructure of Au-catalyzed InGaAs/GaAs nanowires grown by metal-organic chemical vapor deposition

    Science.gov (United States)

    Yuan, Huibo; Li, Lin; Li, Zaijin; Wang, Yong; Qu, Yi; Ma, Xiaohui; Liu, Guojun

    2018-01-01

    Nanowires (NWs) of GaAs and InGaAs/GaAs axial heterostructure are fabricated by metal-organic chemical vapor deposition (MOCVD) following the vapor-liquid-solid (VLS) mechanism. Thin film of Au is coated to generate catalytic droplets and the impact of film thickness on distribution of catalytic droplets is studied. With growth temperature varying, different geometries of GaAs NWs are observed and an assumption has been proposed to explain the phenomenon. InGaAs/GaAs NWs with axial heterostructures are synthesized. Most of InGaAs/GaAs NWs are perpendicular to substrates with cylindrical morphology and distinct heterostructure interface. Energy Dispersive X-ray Spectroscopy (EDX) line-scan's been applied to investigate the concentration changes of nanowires, indicating pure axial heterostructures without radial growth.

  12. chemical studies and sorption behavior of some hazardous metal ions on polyacrylamide stannic (IV) molybdophosphate as 'organic - inorganic' composite cation - exchanger

    International Nuclear Information System (INIS)

    Abdel-Galil, E.A.M.

    2010-01-01

    compsite materials formed by the combination of multivalent metal acid salts and organic polymers provide a new class of (organic-inorganic) hypride ion exchangers with better mechanical and granulometric properties, good ion-exchange capacity, higher chemical and radiation stabilites, reproducibility and selectivity for heavy metals. this material was characterized using X-ray (XRD and XRF), IR, TGA-DTA and total elemental analysis studies. on the basis of distribution studies, the material has been found to be highly selective for pb(II). thermodynamic parameters (i.e δG 0 , δ S 0 and δH 0 ) have also been calculated for the adsorption of Pb 2+ , Cs + , Fe 3+ , Cd 2+ , Cu +2 , Zn 2+ , Co 2+ and Eu 3+ ions on polyacrylamide Sn(IV) molybdophosphate showing that the overall adsorption process is spontaneous endothermic. the mechanism of diffusion of Fe 3+ , Co 2+ , Cu +2 , Zn 2+ , Cd 2+ , Cs + , Pb 2+ and Eu 3+ in the H-form of polyacrylamide Sn(IV) molybdophosphate composite as cation exchanger was studied as a function of particle size, concentration of the exchanging ions, reaction temperature, dring temperature and pH. the exchange rate was controlled by particle diffusion mechanism as a limited batch techneque and is confirmed from straight lines of B versus 1/r 2 polts. the values of diffusion coefficients, activation energy and entropy of activation were calculated and their significance was discussed. the data obtained have been comared with that reported for other organic and inorganic exchangers.

  13. Cu-Al alloy formation by thermal annealing of Cu/Al multilayer films deposited by cyclic metal organic chemical vapor deposition

    Science.gov (United States)

    Moon, Hock Key; Yoon, Jaehong; Kim, Hyungjun; Lee, Nae-Eung

    2013-05-01

    One of the most important issues in future Cu-based interconnects is to suppress the resistivity increase in the Cu interconnect line while decreasing the line width below 30 nm. For the purpose of mitigating the resistivity increase in the nanoscale Cu line, alloying Cu with traces of other elements is investigated. The formation of a Cu alloy layer using chemical vapor deposition or electroplating has been rarely studied because of the difficulty in forming Cu alloys with elements such as Al. In this work, Cu-Al alloy films were successfully formed after thermal annealing of Cu/Al multilayers deposited by cyclic metal-organic chemical vapor deposition (C-MOCVD). After the C-MOCVD of Cu/Al multilayers without gas phase reaction between the Cu and Al precursors in the reactor, thermal annealing was used to form Cu-Al alloy films with a small Al content fraction. The resistivity of the alloy films was dependent on the Al precursor delivery time and was lower than that of the aluminum-free Cu film. No presence of intermetallic compounds were detected in the alloy films by X-ray diffraction measurements and transmission electron spectroscopy.

  14. An evaluation of absorption spectroscopy to monitor YBa2Cu3O7-x precursors for metal organics chemical vapor deposition processing

    International Nuclear Information System (INIS)

    Matthew Edward Thomas

    1999-01-01

    Absorption spectroscopy was evaluated as a technique to monitor the metal organics chemical vapor deposition (MOCVD) process for forming YBa 2 Cu 3 O 7-x superconducting coated conductors. Specifically, this study analyzed the feasibility of using absorption spectroscopy to monitor the MOCVD supply vapor concentrations of the organic ligand 2,2,6,6-tetramethyl-3,5-heptanedionate (TMHD) metal chelates of barium, copper, and yttrium. Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 compounds have successfully been vaporized in the MOCVD processing technique to form high temperature superconducting ''coated conductors,'' a promising technology for wire fabrication. The absorption study of the barium, copper, and yttrium (TMHD) precursors was conducted in the ultraviolet wavelength region from 200nm to 400nm. To simulate the MOCVD precursor flows the Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 complexes were vaporized at vacuum pressures of (0.03--10)Torr. Spectral absorption scans of each precursor were conducted to examine potential measurement wavelengths for determining vapor concentrations of each precursor via Beer's law. The experimental results show that under vacuum conditions the barium, copper, and yttrium (TMHD) precursors begin to vaporize between 90 C and 135 C, which are considerably lower vaporization temperatures than atmospheric thermal gravimetric analyses indicate. Additionally, complete vaporization of the copper and yttrium (TMHD) precursors occurred during rapid heating at temperatures between 145 C and 195 C and after heating at constant temperatures between 90 C and 125 C for approximately one hour, whereas the Ba(TMHD) 2 precursor did not completely vaporize. At constant temperatures, near constant vaporization levels for each precursor were observed for extended periods of time. Detailed spectroscopic scans at stable vaporization conditions were conducted

  15. Epitaxial growth of CdTe thin film on cube-textured Ni by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Gaire, C.; Rao, S.; Riley, M.; Chen, L.; Goyal, A.; Lee, S.; Bhat, I.; Lu, T.-M.; Wang, G.-C.

    2012-01-01

    Single crystal-like CdTe thin film has been grown by metalorganic chemical vapor deposition on cube-textured Ni(100) substrate. Using X-ray pole figure measurements we observed the epitaxial relationship of {111} CdTe //{001} Ni with [11 ¯ 0] CdTe //[010] Ni and [112 ¯ ] CdTe //[100] Ni . The 12 diffraction peaks in the (111) pole figure of CdTe film and their relative positions with respect to the four peak positions in the (111) pole figure of Ni substrate are consistent with four equivalent orientational domains of CdTe with three to four superlattice match of about 1.6% in the [11 ¯ 0] direction of CdTe and the [010] direction of Ni. The electron backscattered diffraction images show that the CdTe domains are 30° oriented from each other. These high structural quality films may find applications in low cost optoelectronic devices.

  16. Post-synthesis amine borane functionalization of metal-organic framework and its unusual chemical hydrogen release phenomenon

    KAUST Repository

    Berke, Heinz

    2017-05-11

    We report a novel strategy for post-synthesis amine borane functionalization of MOFs under gas-solid phase transformation utilizing gaseous diborane. The covalently confined amine borane derivative decorated on the framework backbone is stable when preserved at low temperature, but spontaneously liberates soft chemical hydrogen at room temperature leading to the development of an unusual borenium type species (-NH=BH2+) ion-paired with hydroborate anion. Furthermore, the unsaturated amino borane (-NH=BH2) and the -iminodiborane ((--NHB2H5) were detected as final products. A combination of DFT based molecular dynamics simulations and solid state NMR spectroscopy, utilizing isotopically enriched materials, were undertaken to unequivocally elucidate the mechanistic pathways for H2 liberation.

  17. Physical-chemical and technological aspects of the preparation of think layers of the high temperature superconductors Bi-Sr-Ca-Cu-O by method of metal organic vapour phase epitaxy

    International Nuclear Information System (INIS)

    Stejskal, J.; Nevriva, M.; Leitner, J.

    1995-01-01

    The method of metal organic vapour phase epitaxy (MO VPE) was used for preparation of think layers of the high temperature superconductors Bi-Sr-Ca-Cu-O. The suitable chemical precursors (β-diketonates) on the literature data and of the own thermodynamic calculations were selected. The optimal thermodynamic data and thermodynamic stability of the prepared samples were determined

  18. Epitaxial growth of CdTe thin film on cube-textured Ni by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gaire, C. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States); Rao, S. [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States); Riley, M. [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States); Chen, L. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States); Goyal, A. [Oak Ridge National Lab, Oak ridge, TN, 37831-6116 (United States); Lee, S. [US Army ARDEC Benet Labs, Watervliet, NY, 12189-4050 (United States); Bhat, I. [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States); Lu, T.-M. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States); Wang, G.-C., E-mail: wangg@rpi.edu [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180-3590 (United States)

    2012-01-01

    Single crystal-like CdTe thin film has been grown by metalorganic chemical vapor deposition on cube-textured Ni(100) substrate. Using X-ray pole figure measurements we observed the epitaxial relationship of {l_brace}111{r_brace}{sub CdTe}//{l_brace}001{r_brace}{sub Ni} with [11{sup Macron }0]{sub CdTe}//[010]{sub Ni} and [112{sup Macron }] {sub CdTe}//[100]{sub Ni}. The 12 diffraction peaks in the (111) pole figure of CdTe film and their relative positions with respect to the four peak positions in the (111) pole figure of Ni substrate are consistent with four equivalent orientational domains of CdTe with three to four superlattice match of about 1.6% in the [11{sup Macron }0] direction of CdTe and the [010] direction of Ni. The electron backscattered diffraction images show that the CdTe domains are 30 Degree-Sign oriented from each other. These high structural quality films may find applications in low cost optoelectronic devices.

  19. Self-Catalyzed Growth of Vertical GaSb Nanowires on InAs Stems by Metal-Organic Chemical Vapor Deposition

    Science.gov (United States)

    Ji, Xianghai; Yang, Xiaoguang; Yang, Tao

    2017-06-01

    We report the first self-catalyzed growth of high-quality GaSb nanowires on InAs stems using metal-organic chemical vapor deposition (MOCVD) on Si (111) substrates. To achieve the growth of vertical InAs/GaSb heterostructure nanowires, the two-step flow rates of the trimethylgallium (TMGa) and trimethylantimony (TMSb) are used. We first use relatively low TMGa and TMSb flow rates to preserve the Ga droplets on the thin InAs stems. Then, the flow rates of TMGa and TMSb are increased to enhance the axial growth rate. Because of the slower radial growth rate of GaSb at higher growth temperature, GaSb nanowires grown at 500 °C exhibit larger diameters than those grown at 520 °C. However, with respect to the axial growth, due to the Gibbs-Thomson effect and the reduction in the droplet supersaturation with increasing growth temperature, GaSb nanowires grown at 500 °C are longer than those grown at 520 °C. Detailed transmission electron microscopy (TEM) analyses reveal that the GaSb nanowires have a perfect zinc-blende (ZB) crystal structure. The growth method presented here may be suitable for other antimonide nanowire growth, and the axial InAs/GaSb heterostructure nanowires may have strong potential for use in the fabrication of novel nanowire-based devices and in the study of fundamental quantum physics.

  20. Structural, electrical and optical properties of indium tin oxide thin film grown by metal organic chemical vapor deposition with tetramethyltin-precursor

    Science.gov (United States)

    Zhuo, Yi; Chen, Zimin; Tu, Wenbin; Ma, Xuejin; Wang, Gang

    2018-01-01

    Tin-doped indium oxide (ITO) is grown by metal organic chemical vapor deposition (MOCVD) using tetramethyltin (TDMASn) as tin precursor. The as-grown ITO films are polycrystalline with (111) and (100) textures. A gradual transition of crystallographic orientation from (111) preferred to (100) preferred is observed as the composition of tin changes. By precisely controlling the Sn doping, the ITO thin films present promising optical and electrical performances at either near-infrared-visible or visible-near-ultraviolet ranges. At low Sn doping level, the as-grown ITO possesses high electron mobility of 48.8 cm2 V‑1 s‑1, which results in high near-infrared transmittance and low resistivity. At higher Sn doping level, high carrier concentration (8.9 × 1020 cm‑3) and low resistivity (3 × 10‑4 Ω cm) are achieved. The transmittance is 97.8, 99.1, and 82.3% at the wavelength of 550, 365, and 320 nm, respectively. The results strongly suggest that MOCVD with TDMASn as tin precursor is an effective method to fabricate high quality ITO thin film for near-infrared, visible light, and near-ultraviolet application.

  1. High-resistivity unintentionally carbon-doped GaN layers with nitrogen as nucleation layer carrier gas grown by metal-organic chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Fu Chen

    2017-12-01

    Full Text Available In this letter, high-resistivity unintentionally carbon-doped GaN layers with sheet resistivity greater than 106 Ω/□ have been grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD. We have observed that the growth of GaN nucleation layers (NLs under N2 ambient leads to a large full width at half maximum (FWHM of (102 X-ray diffraction (XRD line in the rocking curve about 1576 arc sec. Unintentional carbon incorporation can be observed in the secondary ion mass spectroscopy (SIMS measurements. The results demonstrate the self-compensation mechanism is attributed to the increased density of edge-type threading dislocations and carbon impurities. The AlGaN/GaN HEMT grown on the high-resistivity GaN template has also been fabricated, exhibiting a maximum drain current of 478 mA/mm, a peak transconductance of 60.0 mS/mm, an ON/OFF ratio of 0.96×108 and a breakdown voltage of 621 V.

  2. Formation and characterization of the MgO protecting layer deposited by plasma-enhanced metal-organic chemical-vapor deposition

    CERN Document Server

    Kang, M S; Byun, J C; Kim, D S; Choi, C K; Lee, J Y; Kim, K H

    1999-01-01

    MgO films were prepared on Si(100) and soda-lime glass substrates by using plasma-enhanced metal-organic chemical-vapor deposition. Various ratios of the O sub 2 /CH sub 3 MgO sup t Bu gas mixture and various gas flow rates were tested for the film fabrications. Highly (100)-oriented MgO films with good crystallinity were obtained with a 10 sccm CH sub 3 MgO sup t Bu flow without an O sub 2 gas flow. About 5 % carbon was contained in all the MgO films. The refractive index and the secondary electron emission coefficient for the best quality film were 1.43 and 0.45, respectively. The sputtering rate was about 0.2 nm/min for 10 sup 1 sup 1 cm sup - sup 3 Ar sup + ion density. Annealing at 500 .deg. C in an Ar ambient promoted the grain size without inducing a phase transition.

  3. Fabrication of high-quality Y-Ba-Cu-O thin films by plasma-enhanced metal-organic chemical vapor deposition

    Science.gov (United States)

    Zhao, J.; Norris, P.

    The great versatility of plasma-enhanced metal-organic chemical vapor deposition (PE-MOCVD) in its application to the growth of high-quality YBa2Cu3O(7-x) (YBCO) has been demonstrated. Single-crystal epitaxial YBCO thin films with sharp superconducting transition temperatures above 89 K and critical current densities greater than 1 x 10(exp 6) A/sq cm at 77 K were formed in-situ by PE-MOCVD at a low substrate temperature of 670 C and a high oxygen partial pressure of 1 Torr. Our results reveal that high-quality YBCO thin films can be formed over an anomalously wide range of film compositions. The high degree of epitaxial crystallinity of the films was confirmed by Rutherford backscattering spectroscopy which gave a minimum channeling yield of 9%. High-resolution transmission electron microscopy revealed that the films grew epitaxially with the c axis normal to the substrate surface and atomically abrupt interface.

  4. Enhanced and uniform in-field performance in long (Gd, Y)-Ba-Cu-O tapes with zirconium doping fabricated by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Selvamanickam, V; Guevara, A; Zhang, Y; Kesgin, I; Xie, Y; Carota, G; Chen, Y; Dackow, J; Zhang, Y; Zuev, Y; Cantoni, C; Goyal, A; Coulter, J; Civale, L

    2010-01-01

    The influence of Zr doping in (Gd, Y)-Ba-Cu-O ((Gd, Y)BCO) tapes made by metal-organic chemical vapor deposition has been studied with a specific objective of uniform and reproducible enhancement in in-field critical current (I c ) over long lengths. 50 m long tapes with 7.5 and 10 at.% Zr doping in 1 μm thick (Gd, Y)BCO films have been found to exhibit a sharply enhanced peak in I c in the orientation of field parallel to the c-axis and retain 28% of their self-field I c value at 77 K and 1 T. BaZrO 3 (BZO) nanocolumn density in the cross-sectional microstructure was found to increase with increasing Zr addition. The end segments of the 50 m long tapes were found to display nearly identical angular dependence of critical current at 77 K and 1 T, indicative of the uniformity in in-field performance over this length. A 610 m long tape was fabricated with 10% Zr doping and a 130 m segment showed a 3.2% uniformity in critical current measured every meter in the orientation of B || c-axis. A retention factor of 36% of the zero-field I c value measured at 0.52 T over the 130 m is consistent with that obtained in short samples.

  5. Enhanced and uniform in-field performance in long (Gd, Y)-Ba-Cu-O tapes with zirconium doping fabricated by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V; Guevara, A; Zhang, Y; Kesgin, I [Texas Center for Superconductivity and Department of Mechanical Engineering, University of Houston, Houston, TX 77059 (United States); Xie, Y; Carota, G; Chen, Y; Dackow, J [SuperPower Incorporated, 450 Duane Avenue Schenectady, NY 12304 (United States); Zhang, Y; Zuev, Y; Cantoni, C; Goyal, A [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Coulter, J; Civale, L [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2010-01-15

    The influence of Zr doping in (Gd, Y)-Ba-Cu-O ((Gd, Y)BCO) tapes made by metal-organic chemical vapor deposition has been studied with a specific objective of uniform and reproducible enhancement in in-field critical current (I{sub c}) over long lengths. 50 m long tapes with 7.5 and 10 at.% Zr doping in 1 {mu}m thick (Gd, Y)BCO films have been found to exhibit a sharply enhanced peak in I{sub c} in the orientation of field parallel to the c-axis and retain 28% of their self-field I{sub c} value at 77 K and 1 T. BaZrO{sub 3} (BZO) nanocolumn density in the cross-sectional microstructure was found to increase with increasing Zr addition. The end segments of the 50 m long tapes were found to display nearly identical angular dependence of critical current at 77 K and 1 T, indicative of the uniformity in in-field performance over this length. A 610 m long tape was fabricated with 10% Zr doping and a 130 m segment showed a 3.2% uniformity in critical current measured every meter in the orientation of B || c-axis. A retention factor of 36% of the zero-field I{sub c} value measured at 0.52 T over the 130 m is consistent with that obtained in short samples.

  6. Influence of Zr and Ce doping on electromagnetic properties of (Gd,Y)-Ba-Cu-O superconducting tapes fabricated by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Selvamanickam, V.; Chen, Y.; Xie, J.; Zhang, Y.; Guevara, A.; Kesgin, I.; Majkic, G.; Martchevsky, M.

    2009-01-01

    (Gd,Y)Ba 2 Cu 3 O x tapes have been fabricated by metal organic chemical vapor deposition (MOCVD) with Zr-doping levels of 0-15 mol.% and Ce doping levels of 0-10 mol.% in 0.4 μm thick films. The critical current density (J c ) of Zr-doped samples at 77 K, 1 T applied in the orientation of H -parallel c is found to increase with Zr content and shows a maximum at 7.5% Zr doping. The 7.5% Zr-doped sample exhibits a critical current density (J c ) of 0.95 MA/cm 2 at H -parallel c which is more than 70% higher than the J c of the undoped sample. The peak in J c at H -parallel c is 83% of that at H -parallel a-b in the 7.5% Zr-doped sample which is more than twice as that in the undoped sample. Superconducting transition temperature (T c ) values as high as about 89 K have been achieved in samples even with 15% Zr and 10% Ce. Ce-doped samples with and without Ba compensation are found to exhibit substantially different J c values as well as angular dependence characteristics.

  7. Enhanced and Uniform in-Field Performance in Long (Gd,Y)-Ba-Cu-O Tapes with Zirconium Doping Fabricated by Metal Organic Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Guevara, A. [University of Houston, Houston; Zhang, Y. [University of Houston, Houston; Kesign, I. [University of Houston, Houston; Xie, Y. Y. [SuperPower Incorporated, Schenectady, New York; Carota, G. [SuperPower Incorporated, Schenectady, New York; Chen, Y. [SuperPower Incorporated, Schenectady, New York; Dackow, J. [SuperPower Incorporated, Schenectady, New York; Zhang, Yifei [ORNL; Zuev, Yuri L [ORNL; Cantoni, Claudia [ORNL; Goyal, Amit [ORNL; Coulter, J. [Los Alamos National Laboratory (LANL); Civale, L. [Los Alamos National Laboratory (LANL)

    2010-01-01

    The influence of Zr doping in (Gd, Y)-Ba-Cu-O ((Gd, Y)BCO) tapes made by metal-organic chemical vapor deposition has been studied with a specific objective of uniform and reproducible enhancement in in-field critical current (I{sub c}) over long lengths. 50 m long tapes with 7.5 and 10 at.% Zr doping in 1 {mu}m thick (Gd, Y)BCO films have been found to exhibit a sharply enhanced peak in I{sub c} in the orientation of field parallel to the c-axis and retain 28% of their self-field I{sub c} value at 77 K and 1 T. BaZrO{sub 3} (BZO) nanocolumn density in the cross-sectional microstructure was found to increase with increasing Zr addition. The end segments of the 50 m long tapes were found to display nearly identical angular dependence of critical current at 77 K and 1 T, indicative of the uniformity in in-field performance over this length. A 610 m long tape was fabricated with 10% Zr doping and a 130 m segment showed a 3.2% uniformity in critical current measured every meter in the orientation of {beta} {parallel} c-axis. A retention factor of 36% of the zero-field I{sub c} value measured at 0.52 T over the 130 m is consistent with that obtained in short samples.

  8. Influence of Zr and Ce doping on electromagnetic properties of (Gd,Y)-Ba-Cu-O superconducting tapes fabricated by metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V., E-mail: selva@uh.ed [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Rd., Houston, TX 77204-4006 (United States); Chen, Y.; Xie, J. [SuperPower Inc., 450 Duane Ave., Schenectady, NY 12304 (United States); Zhang, Y.; Guevara, A.; Kesgin, I.; Majkic, G. [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Rd., Houston, TX 77204-4006 (United States); Martchevsky, M. [SuperPower Inc., 450 Duane Ave., Schenectady, NY 12304 (United States)

    2009-12-01

    (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub x} tapes have been fabricated by metal organic chemical vapor deposition (MOCVD) with Zr-doping levels of 0-15 mol.% and Ce doping levels of 0-10 mol.% in 0.4 mum thick films. The critical current density (J{sub c}) of Zr-doped samples at 77 K, 1 T applied in the orientation of H -parallel c is found to increase with Zr content and shows a maximum at 7.5% Zr doping. The 7.5% Zr-doped sample exhibits a critical current density (J{sub c}) of 0.95 MA/cm{sup 2} at H -parallel c which is more than 70% higher than the J{sub c} of the undoped sample. The peak in J{sub c} at H -parallel c is 83% of that at H -parallel a-b in the 7.5% Zr-doped sample which is more than twice as that in the undoped sample. Superconducting transition temperature (T{sub c}) values as high as about 89 K have been achieved in samples even with 15% Zr and 10% Ce. Ce-doped samples with and without Ba compensation are found to exhibit substantially different J{sub c} values as well as angular dependence characteristics.

  9. The Structural Evolution of (Gd, Y)Ba2Cu3Ox Tapes With Zr Addition Made by Metal Organic Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lei, CH; Galstyan, E; Chen, YM; Shi, T; Liu, YH; Khatri, N; Liu, JF; Xiong, XM; Majkic, G; Selvamanickam, V

    2013-06-01

    Structural analysis of (Gd, Y) Ba2Cu3Ox tapes with Zr addition made by metal organic chemical vapor deposition has been conducted with transmission electron microscopy and X-ray diffraction. Zr content in the films was varied from 0 to 25% in the precursor. In all Zr-doped films, self-assembled nanocolumnar structures of BaZrO3 (BZO) were observed along the c-axis. The amount of BaZrO3 was found to increase steadily with Zr content. Additionally, planar BZO plates were found on the (001) plane of (Gd, Y) Ba2Cu3Ox film. The size and thickness of BZO plates were seen to increase with Zr doping level. Rare-earth copper oxide phases were observed to begin to emerge in the 20% Zr-doped film. Cross-sectional study of the interface between (Gd, Y)Ba2Cu3Ox and LaMnO3 cap layer revealed a thin discrete BZO layer on the LaMnO3 in the 20% Zr doped film.

  10. Cyclodextrin-based metal-organic frameworks particles as efficient carriers for lansoprazole: Study of morphology and chemical composition of individual particles.

    Science.gov (United States)

    Li, Xue; Guo, Tao; Lachmanski, Laurent; Manoli, Francesco; Menendez-Miranda, Mario; Manet, Ilse; Guo, Zhen; Wu, Li; Zhang, Jiwen; Gref, Ruxandra

    2017-10-15

    Cyclodextrin-based metal-organic frameworks (CD-MOFs) represent an environment-friendly and biocompatible class of MOFs drawing increasing attention in drug delivery. Lansoprazole (LPZ) is a proton-pump inhibitor used to reduce the production of acid in the stomach and recently identified as an antitubercular prodrug. Herein, LPZ loaded CD-MOFs were successfully synthesized upon the assembly with γ-CD in the presence of K + ions using an optimized co-crystallization method. They were characterized in terms of morphology, size and crystallinity, showing almost perfect cubic morphologies with monodispersed size distributions. The crystalline particles, loaded or not with LPZ, have mean diameters of around 6μm. The payloads reached 23.2±2.1% (wt) which corresponds to a molar ratio of 1:1 between LPZ and γ-CD. It was demonstrated that even after two years storage, the incorporated drug inside the CD-MOFs maintained its spectroscopic characteristics. Molecular modelling provided a deeper insight into the interaction between the LPZ and CD-MOFs. Raman spectra of individual particles were recorded, confirming the formation of inclusion complexes within the tridimensional CD-MOF structures. Of note, it was found that each individual particle had the same chemical composition. The LPZ-loaded particles had remarkable homogeneity in terms of both drug loading and size. These results pave the way towards the use of CD-MOFs for drug delivery purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Catalyst-free selective-area epitaxy of GaAs nanowires by metal-organic chemical vapor deposition using triethylgallium

    Science.gov (United States)

    Kim, Hyunseok; Ren, Dingkun; Farrell, Alan C.; Huffaker, Diana L.

    2018-02-01

    We demonstrate catalyst-free growth of GaAs nanowires by selective-area metal-organic chemical vapor deposition (MOCVD) on GaAs and silicon substrates using a triethylgallium (TEGa) precursor. Two-temperature growth of GaAs nanowires—nucleation at low temperature followed by nanowire elongation at high temperature—almost completely suppresses the radial overgrowth of nanowires on GaAs substrates while exhibiting a vertical growth yield of almost 100%. A 100% growth yield is also achieved on silicon substrates by terminating Si(111) surfaces by arsenic prior to the nanowire growth and optimizing the growth temperature. Compared with trimethylgallium (TMGa) which has been exclusively employed in the vapor–solid phase growth of GaAs nanowires by MOCVD, the proposed growth technique using TEGa is advantageous because of lower growth temperature and fully suppressed radial overgrowth. It is also known that GaAs grown by TEGa induce less impurity incorporation compared with TMGa, and therefore the proposed method could be a building block for GaAs nanowire-based high-performance optoelectronic and nanoelectronic devices on both III–V and silicon platforms.

  12. High-resistivity unintentionally carbon-doped GaN layers with nitrogen as nucleation layer carrier gas grown by metal-organic chemical vapor deposition

    Science.gov (United States)

    Chen, Fu; Sun, Shichuang; Deng, Xuguang; Fu, Kai; Yu, Guohao; Song, Liang; Hao, Ronghui; Fan, Yaming; Cai, Yong; Zhang, Baoshun

    2017-12-01

    In this letter, high-resistivity unintentionally carbon-doped GaN layers with sheet resistivity greater than 106 Ω/□ have been grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD). We have observed that the growth of GaN nucleation layers (NLs) under N2 ambient leads to a large full width at half maximum (FWHM) of (102) X-ray diffraction (XRD) line in the rocking curve about 1576 arc sec. Unintentional carbon incorporation can be observed in the secondary ion mass spectroscopy (SIMS) measurements. The results demonstrate the self-compensation mechanism is attributed to the increased density of edge-type threading dislocations and carbon impurities. The AlGaN/GaN HEMT grown on the high-resistivity GaN template has also been fabricated, exhibiting a maximum drain current of 478 mA/mm, a peak transconductance of 60.0 mS/mm, an ON/OFF ratio of 0.96×108 and a breakdown voltage of 621 V.

  13. In-situ wafer bowing measurements of GaN grown on Si (111) substrate by reflectivity mapping in metal organic chemical vapor deposition system

    International Nuclear Information System (INIS)

    Yang Yi-Bin; Liu Ming-Gang; Chen Wei-Jie; Han Xiao-Biao; Chen Jie; Lin Xiu-Qi; Lin Jia-Li; Luo Hui; Liao Qiang; Zang Wen-Jie; Chen Yin-Song; Qiu Yun-Ling; Wu Zhi-Sheng; Liu Yang; Zhang Bai-Jun

    2015-01-01

    In this work, the wafer bowing during growth can be in-situ measured by a reflectivity mapping method in the 3×2″ Thomas Swan close coupled showerhead metal organic chemical vapor deposition (MOCVD) system. The reflectivity mapping method is usually used to measure the film thickness and growth rate. The wafer bowing caused by stresses (tensile and compressive) during the epitaxial growth leads to a temperature variation at different positions on the wafer, and the lower growth temperature leads to a faster growth rate and vice versa. Therefore, the wafer bowing can be measured by analyzing the discrepancy of growth rates at different positions on the wafer. Furthermore, the wafer bowings were confirmed by the ex-situ wafer bowing measurement. High-resistivity and low-resistivity Si substrates were used for epitaxial growth. In comparison with low-resistivity Si substrate, GaN grown on high-resistivity substrate shows a larger wafer bowing caused by the highly compressive stress introduced by compositionally graded AlGaN buffer layer. This transition of wafer bowing can be clearly in-situ measured by using the reflectivity mapping method. (paper)

  14. Doping characteristics of Si-doped n-GaN Epilayers grown by low-pressure metal-organic chemical-vapor deposition

    CERN Document Server

    Noh, S K; Park, S E; Lee, I H; Choi, I H; Son, S J; Lim, K Y; Lee, H J

    1998-01-01

    We studied doping behaviors through analysis of the electronic properties of a series of undoped and Si-doped GaN epilayers grown on (0001) sapphire substrates by the low-pressure metal-organic chemical-vapor deposition (LP-MOCVD) technique. The doping efficiency was in the range of 0.4 - 0.8, and an empirical relation expressed as eta = 0.45 log[Si] - 8.1 was obtained. The temperature dependence of carrier concentration showed that the donor activation energy monotonically decreased from 17.6 meV to almost zero as the doping level increased. We suggest that the reduction in the activation energy is related not to autodoped defect centers but to doped Si donors and that the behavior originates from the formation of an impurity band. On the basis of an abrupt change in the compensation ratio from 0.9 to 0.5 by Si-doping, an exceptional difference in the Hall mobility between the undoped and the Si-doped films is explained by a mixed conduction mechanism of electrons and holes.

  15. As-grown deep-level defects in n-GaN grown by metal-organic chemical vapor deposition on freestanding GaN

    International Nuclear Information System (INIS)

    Chen Shang; Ishikawa, Kenji; Hori, Masaru; Honda, Unhi; Shibata, Tatsunari; Matsumura, Toshiya; Tokuda, Yutaka; Ueda, Hiroyuki; Uesugi, Tsutomu; Kachi, Tetsu

    2012-01-01

    Traps of energy levels E c -0.26 and E c -0.61 eV have been identified as as-grown traps in n-GaN grown by metal-organic chemical vapor deposition by using deep level transient spectroscopy of the Schottky contacts fabricated by resistive evaporation. The additional traps of E c -0.13 and E c -0.65 eV have been observed in samples whose contacts are deposited by electron-beam evaporation. An increase in concentration of the E c -0.13 and E c -0.65 eV traps when approaching the interface between the contact and the GaN film supports our argument that these traps are induced by electron-beam irradiation. Conversely, the depth profiles of as-grown traps show different profiles between several samples with increased or uniform distribution in the near surface below 50 nm. Similar profiles are observed in GaN grown on a sapphire substrate. We conclude that the growth process causes these large concentrations of as-grown traps in the near-surface region. It is speculated that the finishing step in the growth process should be an essential issue in the investigation of the surface state of GaN.

  16. Effect of AlN growth temperature on trap densities of in-situ metal-organic chemical vapor deposition grown AlN/AlGaN/GaN metal-insulator-semiconductor heterostructure field-effect transistors

    Directory of Open Access Journals (Sweden)

    Joseph J. Freedsman

    2012-06-01

    Full Text Available The trapping properties of in-situ metal-organic chemical vapor deposition (MOCVD grown AlN/AlGaN/GaN metal-insulator-semiconductor heterostructure field-effect transistors (MIS-HFETs with AlN layers grown at 600 and 700 °C has been quantitatively analyzed by frequency dependent parallel conductance technique. Both the devices exhibited two kinds of traps densities, due to AlN (DT-AlN and AlGaN layers (DT-AlGaN respectively. The MIS-HFET grown at 600 °C showed a minimum DT-AlN and DT-AlGaN of 1.1 x 1011 and 1.2 x 1010 cm-2eV-1 at energy levels (ET -0.47 and -0.36 eV. Further, the gate-lag measurements on these devices revealed less degradation ∼ ≤ 5% in drain current density (Ids-max. Meanwhile, MIS-HFET grown at 700 °C had more degradation in Ids-max ∼26 %, due to high DT-AlN and DT-AlGaN of 3.4 x 1012 and 5 x 1011 cm-2eV-1 positioned around similar ET. The results shows MIS-HFET grown at 600 °C had better device characteristics with trap densities one order of magnitude lower than MIS-HFET grown at 700 °C.

  17. New rht-Type Metal-Organic Frameworks Decorated with Acylamide Groups for Efficient Carbon Dioxide Capture and Chemical Fixation from Raw Power Plant Flue Gas.

    Science.gov (United States)

    Guo, Xiangyang; Zhou, Zhen; Chen, Cong; Bai, Junfeng; He, Cheng; Duan, Chunying

    2016-11-23

    The combination of carbon dioxide capture and chemical fixation in a one-pot process is attractive for both chemists and governments. The cycloaddition of carbon dioxide with epoxides to produce cyclic carbonates is an atomic economical reaction without any side products. By incorporating acylamide to enhance the binding affinity toward CO 2 , new rht-type metal-organic frameworks (MOFs) with (3, 28) and (3, 24) connected units were constructed. Zn-NTTA with two types of dinuclear paddlewheel building blocks-{Zn 2 (OOC - ) 4 } and {Zn 2 (OOC - ) 3 }. The high uptake of CO 2 (115.6 cm 3 ·g -1 ) and selectivity over N 2 (30:1) at 273 K indicated that these MOFs are excellent candidates for postcombustion CO 2 isolation and capture. The MOFs feature high catalytic activity, rapid dynamics of transformation and excellent stability with turnover number (TON) values up to 110 000 per paddlewheel unit after 5 × 6 rounds of recyclability, demonstrating that they are promising heterogeneous catalysts for CO 2 cyclo-addition to value-added cyclic carbonates. The cycloaddition of epoxides with wet gases demonstrated that the catalyst activity was not affected by moisture, and the indices of the PXRD patterns of the bulk samples filtered from the catalytic reaction revealed that the crystallinities were maintained. The combination of the selective capture and catalytic transformation in one-pot enables the use of a negative-cost feedstock-raw power plant flue gas without any separation and purification-revealing the broad prospects of such MOFs for practical CO 2 fixation in industry.

  18. In-situ wafer bowing measurements of GaN grown on Si (111) substrate by reflectivity mapping in metal organic chemical vapor deposition system

    Science.gov (United States)

    Yang, Yi-Bin; Liu, Ming-Gang; Chen, Wei-Jie; Han, Xiao-Biao; Chen, Jie; Lin, Xiu-Qi; Lin, Jia-Li; Luo, Hui; Liao, Qiang; Zang, Wen-Jie; Chen, Yin-Song; Qiu, Yun-Ling; Wu, Zhi-Sheng; Liu, Yang; Zhang, Bai-Jun

    2015-09-01

    In this work, the wafer bowing during growth can be in-situ measured by a reflectivity mapping method in the 3×2″ Thomas Swan close coupled showerhead metal organic chemical vapor deposition (MOCVD) system. The reflectivity mapping method is usually used to measure the film thickness and growth rate. The wafer bowing caused by stresses (tensile and compressive) during the epitaxial growth leads to a temperature variation at different positions on the wafer, and the lower growth temperature leads to a faster growth rate and vice versa. Therefore, the wafer bowing can be measured by analyzing the discrepancy of growth rates at different positions on the wafer. Furthermore, the wafer bowings were confirmed by the ex-situ wafer bowing measurement. High-resistivity and low-resistivity Si substrates were used for epitaxial growth. In comparison with low-resistivity Si substrate, GaN grown on high-resistivity substrate shows a larger wafer bowing caused by the highly compressive stress introduced by compositionally graded AlGaN buffer layer. This transition of wafer bowing can be clearly in-situ measured by using the reflectivity mapping method. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274039 and 51177175), the National Basic Research Program of China (Grant No. 2011CB301903), the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20110171110021), the International Science and Technology Collaboration Program of China (Grant No. 2012DFG52260), the International Science and Technology Collaboration Program of Guangdong Province, China (Grant No. 2013B051000041), the Science and Technology Plan of Guangdong Province, China (Grant No. 2013B010401013), the National High Technology Research and Development Program of China (Grant No. 2014AA032606), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics, China (Grant No. IOSKL2014KF17).

  19. Heavy metals in Antarctic organisms

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, J.E.A. de; Moreno, V.J. [Universidad Nacional de Mar del Plata (Argentina); Gerpe, M.S.; Vodopivez, C. [Instituto Antartico Argentino, Buenos Aires (Argentina)

    1997-02-01

    To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental changes. 46 refs., 7 figs., 8 tabs.

  20. Multifunctional Metal-Organic Frameworks for Photocatalysis.

    Science.gov (United States)

    Wang, Sibo; Wang, Xinchen

    2015-07-01

    Metal-organic frameworks (MOFs) have attracted significant research attention in diverse areas due to their unique physical and chemical characteristics that allow their innovative application in various research fields. Recently, the application of MOFs in heterogeneous photocatalysis for water splitting, CO2 reduction, and organic transformation have emerged, aiming at providing alternative solutions to address the world-wide energy and environmental problems by taking advantage of the unique porous structure together with ample physicochemical properties of the metal centers and organic ligands in MOFs. In this review, the latest progress in MOF-involved solar-to-chemical energy conversion reactions are summarized according to their different roles in the photoredox chemical systems, e.g., photocatalysts, co-catalysts, and hosts. The achieved progress and existing problems are evaluated and proposed, and the opportunities and challenges of MOFs and their related materials for their advanced development in photocatalysis are discussed and anticipated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Selective Metal-vapor Deposition on Organic Surfaces.

    Science.gov (United States)

    Tsujioka, Tsuyoshi

    2016-02-01

    Selective metal-vapor deposition signifies that metal-vapor atoms are deposited on a hard organic surface, but not on a soft (low glass transition temperature, low Tg ) surface. In this paper, we introduce the origin, extension, and applications of selective metal-vapor deposition. An amorphous photochromic diarylethene film shows light-controlled selective metal-vapor deposition, which is caused by a large Tg change based on photoisomerization, but various organic surfaces, including organic crystal and polymers, can be utilized for achieving selective metal-vapor deposition. Various applications of selective metal-vapor deposition, including cathode patterning of organic light-emitting devices, micro-thin-film fuses, multifunctional diffraction gratings, in-plane electrical bistability for memory devices, and metal-vapor integration, have been demonstrated. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    Abstract. Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force ...

  3. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force microscopy ...

  4. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes.

    Science.gov (United States)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X; Urban, Ania; Thacker, Nathan C; Lin, Wenbin

    2016-08-30

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  5. The effect of thermal annealing on the adherence of Al2O3-films deposited by low-pressure, metal-organic, chemical-vapor deposition on AISI 304

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van de Vendel, D.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin alumina films, deposited at 280°C by low-pressure, metal-organic, chemical-vapor deposition on stainless steel, type AISI 304, were annealed at 0.17 kPa in a nitrogen atmosphere for 2,4, and 17 hr at 600, 700, and 800°C. The effect of the annealing process on the adhesion of the thin alumina

  6. Thin films of metal-organic compounds and metal nanoparticle

    Indian Academy of Sciences (India)

    Thin films of metal-organic compounds and metal nanoparticle-embedded polymers for nonlinear optical applications. S Philip Anthony Shatabdi Porel D ... Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which ...

  7. Microstructural and superconducting properties of high current metal-organic chemical vapor deposition YBa2Cu3O7-δ coated conductor wires

    International Nuclear Information System (INIS)

    Holesinger, T G; Maiorov, B; Ugurlu, O; Civale, L; Chen, Y; Xiong, X; Xie, Y; Selvamanickam, V

    2009-01-01

    Metal-organic chemical vapor deposition (MOCVD) on flexible, ion beam assisted deposition MgO templates has been used to produce high critical current density (J c ) (Y,Sm) 1 Ba 2 Cu 3 O y (REBCO) films suitable for use in producing practical high temperature superconducting (HTS) coated conductor wires. Thick films on tape were produced with sequential additions of 0.7 μm of REBCO via a reel-to-reel progression through a custom-designed MOCVD reactor. Multi-pass processing for thick film deposition is critically dependent upon minimizing surface secondary phase formation. Critical currents (I c s) of up to 600 A/cm width (t = 2.8 μm, J c = 2.6 MA cm -2 , 77 K, self-field) were obtained in short lengths of HTS wires. These high performance MOCVD films are characterized by closely spaced (Y,Sm) 2 O 3 nanoparticle layers that may be tilted relative to the film normal and REBCO orientation. Small shifts in the angular dependence of J c in low and intermediate applied magnetic fields can be associated with the tilted nanoparticle layers. Also present in these films were YCuO 2 nanoplates aligned with the YBCO matrix (short dimension perpendicular to the film normal), threading dislocations, and oriented composite defects (OCDs). The latter structures consist of single or multiple a-axis oriented grains coated on each side with insulating (Y,Sm) 2 O 3 or CuO. The OCDs formed a connected network of insulating phases by the end of the fourth pass. Subsequent attempts at adding additional layers did not increase I c . There is an inconsistency between the measured J c and the observed microstructural degradation that occurs with each additional layer, suggesting that previously deposited layers are improving with each repeated reactor pass. These dynamic changes suggest a role for post-processing to optimize superconducting properties of as-deposited films, addressing issues associated with reproducibility and manufacturing yield.

  8. Nanomaterials derived from metal-organic frameworks

    Science.gov (United States)

    Dang, Song; Zhu, Qi-Long; Xu, Qiang

    2018-01-01

    The thermal transformation of metal-organic frameworks (MOFs) generates a variety of nanostructured materials, including carbon-based materials, metal oxides, metal chalcogenides, metal phosphides and metal carbides. These derivatives of MOFs have characteristics such as high surface areas, permanent porosities and controllable functionalities that enable their good performance in sensing, gas storage, catalysis and energy-related applications. Although progress has been made to tune the morphologies of MOF-derived structures at the nanometre scale, it remains crucial to further our knowledge of the relationship between morphology and performance. In this Review, we summarize the synthetic strategies and optimized methods that enable control over the size, morphology, composition and structure of the derived nanomaterials. In addition, we compare the performance of materials prepared by the MOF-templated strategy and other synthetic methods. Our aim is to reveal the relationship between the morphology and the physico-chemical properties of MOF-derived nanostructures to optimize their performance for applications such as sensing, catalysis, and energy storage and conversion.

  9. Metal-organic frameworks in chromatography.

    Science.gov (United States)

    Yusuf, Kareem; Aqel, Ahmad; ALOthman, Zeid

    2014-06-27

    Metal-organic frameworks (MOFs) emerged approximately two decades ago and are the youngest class of porous materials. Despite their short existence, MOFs are finding applications in a variety of fields because of their outstanding chemical and physical properties. This review article focuses on the applications of MOFs in chromatography, including high-performance liquid chromatography (HPLC), gas chromatography (GC), and other chromatographic techniques. The use of MOFs in chromatography has already had a significant impact; however, the utilisation of MOFs in chromatography is still less common than other applications, and the number of MOF materials explored in chromatography applications is limited. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Microwaves in organic chemistry and organic chemical

    Directory of Open Access Journals (Sweden)

    Mijin Dušan Ž.

    2005-01-01

    Full Text Available The usual way of applying heat to a chemical reaction is the use of a Bunsen burner, an oil or some other type of bath, or an electric heater. In inorganic chemistry, microwave technology has been used since the late 1970s while it has been implemented in organic chemistry since the mid-1980s. Microwave heating has been used in the food industry for almost fifty years. The shorter reaction times and expanded reaction range that is offered by microwave technology are suited to the increased demands in industry. For example, there is a requirement in the pharmaceutical industry for a higher number of a novel chemical entities to be produced, which requires chemists to employ a number of resources to reduce time for the production of compounds. Also, microwaves are used in the food industry, as well as in the pyrolysis of waste materials, sample preparation, the solvent extraction of natural products and the hydrolysis of proteins and peptides.

  11. Fiber-optic-based chemical sensors for in-situ measurement of metals and aromatic organic compounds in seawater and soil systems

    Science.gov (United States)

    Lieberman, Stephen H.; Inman, Scott; Theriault, Gregory A.; Cooper, Stafford S.; Malone, Philip G.; Shimizu, Yasuhiro; Lurk, Paul W.

    1990-08-01

    Use of UV-visibletransmitting optical fibers for real-time, remote, in situfluorescencemeasurementsof chemical constituents in environmental samples is described. In order to improve the capability of fluorescence techniques for resoMng complex mixtures we have deVelOped a fiber optic-based system that uses a pulsed nrogen laser to induce fluorescence and a time-gated linear photodiode array coupled to a spectrograph for measuring resutting emisalon spectra This permfts rapid extraction of both spectral information and temporal data (fluorescence decay times). The performance of the system for monftoring aromatic hydrocarbons directly in seawater over a bare-ended" fiber optic cable is discussed. Techniques for extending the Capability to determination of metals and other non-fluorescing compounds are presented. A system in which a fluorogenic indicator molecule for metal ions is constantly renewed at the sensing end of the fiber is described that (1)exhibits very fast response times (1 second) and (2)eliminates problems of reversibility common with immobilized indicators. Presently, the pulsed-laser/photodiode fiber optic system is being adapted to a truck-mounted cone penetrometer system for characterizing the distribution of chemical contaminants at hazardous waste sites. The system can push a 35.7 mm diameter rod up to 50 m into the sI at a rate of approximately 2 cm/sec. The penetrometer probe tip will be equipped with sapphire viewing windows that permft one fiber to screen for aromatic orgarc compounds and a fluorogeruc indicator release system that can be used with a second fiber for trace metal screening.

  12. Analytical chemical system for the determination of heavy metals and organic compounds. Annual progress report, December 1, 1978-November 30, 1979

    International Nuclear Information System (INIS)

    Siggia, S.; Barnes, R.M.

    1979-01-01

    Progress has been made in the synthesis and characterization of new resins for sequestering inorganic and organic compounds. The capabilities of the poly(dithiocarbamate) resin have been extended, a new poly(acrylamidoxime) resin prepared and characterized, and a series of resins for organic compounds prepared and tested. Limited actual sample analyses have been performed with these resins. A new inductively coupled plasma source, spectrometer, and computer system have been received and they are undergoing tests and installation. With this system in place, the multielement analysis of metals during the forthcoming period will insure the application of sequestering resins to practical analysis of energy-related materials. An automated sample handling and data system has been designed, some components purchased, and construction is scheduled for 1980

  13. Analytical chemical system for the determination of heavy metals and organic compounds. Annual progress report, December 1, 1978-November 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Siggia, S.; Barnes, R.M.

    1979-10-24

    Progress has been made in the synthesis and characterization of new resins for sequestering inorganic and organic compounds. The capabilities of the poly(dithiocarbamate) resin have been extended, a new poly(acrylamidoxime) resin prepared and characterized, and a series of resins for organic compounds prepared and tested. Limited actual sample analyses have been performed with these resins. A new inductively coupled plasma source, spectrometer, and computer system have been received and they are undergoing tests and installation. With this system in place, the multielement analysis of metals during the forthcoming period will insure the application of sequestering resins to practical analysis of energy-related materials. An automated sample handling and data system has been designed, some components purchased, and construction is scheduled for 1980.

  14. Gas adsorption on metal-organic frameworks

    Science.gov (United States)

    Willis, Richard R [Cary, IL; Low, John J. , Faheem, Syed A.; Benin, Annabelle I [Oak Forest, IL; Snurr, Randall Q [Evanston, IL; Yazaydin, Ahmet Ozgur [Evanston, IL

    2012-07-24

    The present invention involves the use of certain metal organic frameworks that have been treated with water or another metal titrant in the storage of carbon dioxide. The capacity of these frameworks is significantly increased through this treatment.

  15. Superconductivity in Layered Organic Metals

    Directory of Open Access Journals (Sweden)

    Jochen Wosnitza

    2012-04-01

    Full Text Available In this short review, I will give an overview on the current understanding of the superconductivity in quasi-two-dimensional organic metals. Thereby, I will focus on charge-transfer salts based on bis(ethylenedithiotetrathiafulvalene (BEDT-TTF or ET for short. In these materials, strong electronic correlations are clearly evident, resulting in unique phase diagrams. The layered crystallographic structure leads to highly anisotropic electronic as well as superconducting properties. The corresponding very high orbital critical field for in-plane magnetic-field alignment allows for the occurrence of the Fulde–Ferrell– Larkin–Ovchinnikov state as evidenced by thermodynamic measurements. The experimental picture on the nature of the superconducting state is still controversial with evidence both for unconventional as well as for BCS-like superconductivity.

  16. Organic chemicals in the environment

    International Nuclear Information System (INIS)

    Anderson, T.A.; Beauchamp, J.J.; Walton, B.T.

    1991-01-01

    Disappearance of 15 volatile and semivolatile organic compounds was determined in a mixture added to two different soil types using experimental procedures to distinguish abiotic losses from biological degradation over a 7-d period. Losses due to volatilization were quantified and mass balances were calculated for each compound. The compounds (methyl ethyl ketone; tetrahydrofuran; chlorobenzene; benzene; chloroform; carbon tetrachloride; p-xylene; 1,2-dichlorobenzene; cis-1,4-dich-loro-2-butene; 1,2,3-trichloropropane; 2-chloronaphthalene; ethylene dibromide; hexachlorobenzene; nitrobenzene; and toluene) were applied to the soil in a mixture such that the concentration of each chemical was 100 mg/kg soil (dry wt.). Apparent half-lives for the 15 organic compounds ranged from 14 C-toluene, were unsuccessful. Nonreversible sorption and preanalysis storage conditions were considered as contributors to this inability to achieve a mass balance. On the basis of these results, the authors strongly advise positive accounting for all test compounds and degradation products at the conclusion of studies involving volatile and semivolatile compounds

  17. Anomalous dissolution of metals and chemical corrosion

    Directory of Open Access Journals (Sweden)

    DRAGUTIN M. DRAZIC

    2005-03-01

    Full Text Available An overview is given of the anomalous behavior of some metals, in particular Fe and Cr, in acidic aqueous solutions during anodic dissolution. The anomaly is recognizable by the fact that during anodic dissolutionmore material dissolves than would be expected from the Faraday law with the use of the expected valence of the formed ions. Mechanical disintegration, gas bubble blocking, hydrogen embrittlement, passive layer cracking and other possible reasons for such behavior have been discussed. It was shown, as suggested by Kolotyrkin and coworkers, that the reason can be, also, the chemical reaction in which H2O molecules with the metal form metal ions and gaseous H2 in a potential independent process. It occurs simultaneously with the electrochemical corrosion process, but the electrochemical process controls the corrosion potential. On the example of Cr in acid solution itwas shown that the reason for the anomalous behavior is dominantly chemical dissolution, which is considerably faster than the electrochemical corrosion, and that the increasing temperature favors chemical reaction, while the other possible reasons for the anomalous behavior are of negligible effect. This effect is much smaller in the case of Fe, but exists. The possible role of the chemical dissolution reacton and hydrogen evolution during pitting of steels and Al and stress corrosion cracking or corrosion fatigue are discussed.

  18. Chemical segregation in metallic glass nanowires

    International Nuclear Information System (INIS)

    Zhang, Qi; Li, Mo; Li, Qi-Kai

    2014-01-01

    Nanowires made of metallic glass have been actively pursued recently due to the superb and unique properties over those of the crystalline materials. The amorphous nanowires are synthesized either at high temperature or via mechanical disruption using focused ion beam. These processes have potential to cause significant changes in structure and chemical concentration, as well as formation of defect or imperfection, but little is known to date about the possibilities and mechanisms. Here, we report chemical segregation to surfaces and its mechanisms in metallic glass nanowires made of binary Cu and Zr elements from molecular dynamics simulation. Strong concentration deviation are found in the nanowires under the conditions similar to these in experiment via focused ion beam processing, hot imprinting, and casting by rapid cooling from liquid state. Our analysis indicates that non-uniform internal stress distribution is a major cause for the chemical segregation, especially at low temperatures. Extension is discussed for this observation to multicomponent metallic glass nanowires as well as the potential applications and side effects of the composition modulation. The finding also points to the possibility of the mechanical-chemical process that may occur in different settings such as fracture, cavitation, and foams where strong internal stress is present in small length scales

  19. Understanding and optimization of InN and high indium containing InGaN alloys by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Tuna, Oecal

    2013-01-01

    Among the III-nitride semiconductors (Ga,Al,In)N, InN is the most attractive one due to having the narrowest bandgap of 0.64 eV. The revision in the bandgap of InN makes the InGaN more important since one can cover the whole solar spectrum by only changing In composition in an InGaN layer. The comparison of quality of InN and InGaN layers grown using a metal organic chemical vapor deposition (MOCVD) and a molecular beam epitaxy (MBE) methods indicate that growth with MOCVD is the more challenging, again due to the high dissociation temperature of NH 3 relative to the low decomposition temperature of InN (560-570 C). However, there is significant interest in developing an MOCVD process for InN and InGaN growth since MOCVD technology is the technology currently in use for commercial fabrication of group III nitride thin films. This thesis is therefore focused on a study of MOCVD growth of n- and p-type InN and In-rich InGaN films with the goal of providing new information on the influence of growth conditions on the film properties. Initially, a detailed investigation of MOCVD of InN is given. It is shown that MOCVD growth parameters (growth temperature and V/III ratio) have impacts on the layer properties such as In droplet formation on the surface as well as on its electrical and optical properties. PAS is employed for point defect analyzation. It is shown that In vacancies isolated by nitrogen vacancies are the dominant vacancy-type positron traps in InN. A decrease in the N vacancy concentration in InN is observed as a result of the growth temperature increase from 500 to 550 C. This is an indication of a reduction of N vacancy concentration by enhancing NH 3 dissociation at high growth temperature. Results obtained from optical techniques (Raman and PL) are used to estimate the free carrier concentrations in InN. Electrical characterizations are also carried out using Hall measurements. Carrier concentration values obtained by these three techniques revealed a

  20. Chemical vapor deposition of group IIIB metals

    Science.gov (United States)

    Erbil, A.

    1989-11-21

    Coatings of Group IIIB metals and compounds thereof are formed by chemical vapor deposition, in which a heat decomposable organometallic compound of the formula given in the patent where M is a Group IIIB metal, such as lanthanum or yttrium and R is a lower alkyl or alkenyl radical containing from 2 to about 6 carbon atoms, with a heated substrate which is above the decomposition temperature of the organometallic compound. The pure metal is obtained when the compound of the formula 1 is the sole heat decomposable compound present and deposition is carried out under nonoxidizing conditions. Intermetallic compounds such as lanthanum telluride can be deposited from a lanthanum compound of formula 1 and a heat decomposable tellurium compound under nonoxidizing conditions.

  1. Minerals with metal-organic framework structures.

    Science.gov (United States)

    Huskić, Igor; Pekov, Igor V; Krivovichev, Sergey V; Friščić, Tomislav

    2016-08-01

    Metal-organic frameworks (MOFs) are an increasingly important family of advanced materials based on open, nanometer-scale metal-organic architectures, whose design and synthesis are based on the directed assembly of carefully designed subunits. We now demonstrate an unexpected link between mineralogy and MOF chemistry by discovering that the rare organic minerals stepanovite and zhemchuzhnikovite exhibit structures found in well-established magnetic and proton-conducting metal oxalate MOFs. Structures of stepanovite and zhemchuzhnikovite, exhibiting almost nanometer-wide and guest-filled apertures and channels, respectively, change the perspective of MOFs as exclusively artificial materials and represent, so far, unique examples of open framework architectures in organic minerals.

  2. Selected heavy metals speciation in chemically stabilised sewage sludge

    Science.gov (United States)

    Wiśniowska, Ewa; Włodarczyk-Makuła, Marła

    2017-11-01

    Selected heavy metals (Pb, Ni, Cd) were analysed in soil, digested sewage sludge as well as in the sludge stabilised with CaO or Fenton's reagent. The dose of Fenton's reagent was as follows: Fe2+ = 1g.L-1, Fe2+/H2O2=1:100; stabilisation lasted for 2 h. Dose of CaO was equal to 1 g CaO.g d.m.-1 Total concentration of all metals in the digested sewage sludge was higher than in the soil. Chemical stabilisation of sludge with Fenton's reagent increased total metal content in the sludge as a result of total solids removal. Opposite effect was stated when the sludge was mixed with CaO. Also chemical fractions of heavy metals were identified (exchangeable, carbonate bound, iron oxides bound, organic and residual). The results indicate that stabilisation of the sludge with Fenton's reagent increased mobility of heavy metals compared to the digested sludge. Amendment of CaO increased percent share of examined metals in residual fraction, thus immobilised them and decreased their bioavailability.

  3. Understanding and optimization of InN and high indium containing InGaN alloys by metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tuna, Oecal

    2013-07-18

    Among the III-nitride semiconductors (Ga,Al,In)N, InN is the most attractive one due to having the narrowest bandgap of 0.64 eV. The revision in the bandgap of InN makes the InGaN more important since one can cover the whole solar spectrum by only changing In composition in an InGaN layer. The comparison of quality of InN and InGaN layers grown using a metal organic chemical vapor deposition (MOCVD) and a molecular beam epitaxy (MBE) methods indicate that growth with MOCVD is the more challenging, again due to the high dissociation temperature of NH{sub 3} relative to the low decomposition temperature of InN (560-570 C). However, there is significant interest in developing an MOCVD process for InN and InGaN growth since MOCVD technology is the technology currently in use for commercial fabrication of group III nitride thin films. This thesis is therefore focused on a study of MOCVD growth of n- and p-type InN and In-rich InGaN films with the goal of providing new information on the influence of growth conditions on the film properties. Initially, a detailed investigation of MOCVD of InN is given. It is shown that MOCVD growth parameters (growth temperature and V/III ratio) have impacts on the layer properties such as In droplet formation on the surface as well as on its electrical and optical properties. PAS is employed for point defect analyzation. It is shown that In vacancies isolated by nitrogen vacancies are the dominant vacancy-type positron traps in InN. A decrease in the N vacancy concentration in InN is observed as a result of the growth temperature increase from 500 to 550 C. This is an indication of a reduction of N vacancy concentration by enhancing NH{sub 3} dissociation at high growth temperature. Results obtained from optical techniques (Raman and PL) are used to estimate the free carrier concentrations in InN. Electrical characterizations are also carried out using Hall measurements. Carrier concentration values obtained by these three techniques

  4. Lewis acidic metal catalysed organic transformations by designed ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 3. Lewis acidic metal catalysed organic transformations by designed multi-component structures and assemblies. Afsar Ali Amit P Singh Rajeev Gupta. Perspective Articles Volume 122 Issue 3 May 2010 pp ...

  5. Predicting Metal Speciation & Bioavailability via Estimation of Metal-Organic Thermodynamic Properties

    Science.gov (United States)

    Prasad, A.; Howells, A. E.; Shock, E.

    2017-12-01

    The biological fate of any metal depends on its chemical form in the environment. Arsenic for example, is extremely toxic in the form of inorganic As+3 but completely benign in the organic form of arsenobetaine. Thus, given an exhaustive set of reactions and their equilibrium constants (logK), the bioavailability of any metal can be obtained for blood plasma, hydrothermal fluids or any system of interest. While many data exist for metal-inorganic ligands, logK data covering the temperature range of life for metal-organic complexes are sparse. Hence, we decided to estimate metal-organic logK values from correlations with the commonly available values of ligand pKa. Metal ion specific correlations were made with ligands classified according to their electron donor atoms, denticity and other chemical factors. While this approach has been employed before (Carbonaro et al. 2007, GCA 71, 3958-3968), new correlations were developed that provide estimates even when no metal-organic logK is available. In addition, we have used the same methods to make estimates of metal-organic entropy of association (ΔaS), which can provide logK for any temperature of biological relevance. Our current correlations employ logK and ΔaS data from 30 metal ions (like the biologically relevant Fe+3 & Zn+2) and 74 ligands (like formate and ethylenediamine), which can be expanded to estimate the metal-ligand reaction properties for these 30 metal ions with a possibly limitless number of ligands that may belong to our categories of ligands. With the help of such data, copper speciation was obtained for a defined growth medium for methanotrophs employed by Morton et al. (2000, AEM 66, 1730-1733) that agrees with experimental measurements showing that the free metal ion may not be the bioavailable form in all conditions. These results encourage us to keep filling the gaps in metal-organic logK data and continue finding relationships between biological responses (like metal-accumulation ratios

  6. Thin films of metal-organic compounds and metal nanoparticle ...

    Indian Academy of Sciences (India)

    Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which form perfectly polar assemblies in their crystalline state are found to organize as uniaxially oriented crystallites in vapor deposited thin films on glass substrate.

  7. Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents.

    Science.gov (United States)

    Štengl, Václav; Henych, Jiří; Janoš, Pavel; Skoumal, Miroslav

    2016-01-01

    Metal oxides have very important applications in many areas of chemistry, physics and materials science; their properties are dependent on the method of preparation, the morphology and texture. Nanostructured metal oxides can exhibit unique characteristics unlike those of the bulk form depending on their morphology, with a high density of edges, corners and defect surfaces. In recent years, methods have been developed for the preparation of metal oxide powders with tunable control of the primary particle size as well as of a secondary particle size: the size of agglomerates of crystallites. One of the many ways to take advantage of unique properties of nanostructured oxide materials is stoichiometric degradation of chemical warfare agents (CWAs) and volatile organic compounds (VOC) pollutants on their surfaces.

  8. Metal organic frameworks for gas storage

    KAUST Repository

    Alezi, Dalal

    2016-06-09

    Embodiments provide a method of storing a compound using a metal organic framework (MOF). The method includes contacting one or more MOFs with a fluid and sorbing one or more compounds, such as O2 and CH4. O2 and CH4 can be sorbed simultaneously or in series. The metal organic framework can be an M-soc-MOF, wherein M can include aluminum, iron, gallium, indium, vanadium, chromium, titanium, or scandium.

  9. Chemical metallization of KMPR photoresist polymer in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Zeb, Gul [MiQro Innovation Collaborative Centre (C2MI), 45, boul. de l' Aéroport, Bromont, QC, J2L 1S8 (Canada); Mining & Materials Engineering, McGill University, 3610,University Street, Montreal, QC, H3A 0C5 (Canada); Duong, Xuan Truong [Department of Mechanical Engineering, Ecole polytechnique de Montréal, Montréal, QC, H3C 3T5 (Canada); Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam); Vu, Ngoc Pi; Phan, Quang The; Nguyen, Duc Tuong; Ly, Viet Anh [Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam); Salimy, Siamak [ePeer Review LLC, 145 Pine Haven Shores Rd, Suite 1000-X, Shelburne, VT 05482 (United States); Le, Xuan Tuan, E-mail: xuantuan.le@teledyne.com [MiQro Innovation Collaborative Centre (C2MI), 45, boul. de l' Aéroport, Bromont, QC, J2L 1S8 (Canada); Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam)

    2017-06-15

    Highlights: • Electroless deposition of Ni-B film on KMPR photoresist polymer insulator with excellent adhesion has been achieved. • This metallization has been carried out in aqueous solutions at low temperature. • Polyamine palladium complexes grafts serve as seeds for the electroless plating on KMPR. • This electroless metallization process is simple, industrially feasible, chromium-free and environment-friendly. - Abstract: While conventional methods for preparing thin films of metals and metallic alloys on insulating substrates in the field of microelectromechanical systems (MEMS) include vapor deposition techniques, we demonstrate here that electroless deposition can be considered as an alternate efficient approach to metallize the surface of insulating substrates, such as KMPR epoxy photoresist polymer. In comparison with the physical and chemical vapor deposition methods, which are well-established for metallization of photoresist polymers, our electroless nickel plating requires only immersing the substrates into aqueous solutions in open air at low temperatures. Thin films of nickel alloy have been deposited electrolessly on KMPR surface, through a cost-effective and environmental chromium-free process, mediated through direct grafting of amine palladium complexes in aqueous medium. This covalent organic coating provides excellent adhesion between KMPR and the nickel film and allows better control of the palladium catalyst content. Covalent grafting and characterization of the deposited nickel film have been carried out by means of Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques.

  10. Surface morphological properties of CdxZn(1-x)S thin films deposited by low-cost atmospheric pressure metal organic chemical vapour deposition technique (AP-MOCVD)

    Science.gov (United States)

    Kamaruddin, Nurhafiza; Yusoff, Yulisa; Hossain, Towhid; Amin, Nowshad; Akhtaruzzaman, Md.

    2017-11-01

    The CdxZn(1-x)S films have been deposited by low cost atmospheric pressure metal organic chemical vapour deposition (AP-MOCVD) technique and the resulting morphological properties were successfully evaluated for solar cell applications. All morphological properties presented here were investigated by Field-Emission Scanning Microscopy (FESEM) and Energy Dispersive X-Ray (EDX) spectroscopy. It has been observed that the film thickness and grain size have been greatly influenced by the molar ratio of cadmium and zinc, deposition temperature and time. The average grain size of Cd0.5Zn0.5S films (98.16 nm thick) was obtained with deposition temperature and time of 440°C and 2.5 minutes, respectively.

  11. Development of Microwave-Excited Plasma-Enhanced Metal-Organic Chemical Vapor Deposition System for Forming Ferroelectric Sr2(Ta1-x,Nbx)2O7 Thin Film on Amorphous SiO2

    Science.gov (United States)

    Takahashi, Ichirou; Funaiwa, Kiyoshi; Azumi, Keita; Yamashita, Satoru; Shirai, Yasuyuki; Hirayama, Masaki; Teramoto, Akinobu; Sugawa, Shigetoshi; Ohmi, Tadahiro

    2007-04-01

    Sr2(Ta1-x,Nbx)2O7 (STN; x = 0.3) is suitable for use as ferroelectric gate field-effect transistors (FETs) for one-transistor-type ferroelectric memory devices, because it has a low dielectric constant. For applications using metal-ferroelectric-insulator-semiconductor (MFIS) FETs, crystallization of ferroelectric film on insulator is necessary. Perovskite STN can be successfully obtained on amorphous SiO2 by ferroelectric-multilayer-stack (FMLS) deposition, which uses alternating steps of STN sputtering deposition and oxygen radical treatment. In this study, we report on a newly developed microwave-excited plasma-enhanced metal-organic chemical vapor deposition (MOCVD) system, in which STN can be deposited in radical oxygen atmosphere. We succeeded in the fabrication of STN on amorphous SiO2 in a single process. The IrO2/STN (200 nm)/SiO2 (10 nm)/p-type Si device shows capacitance-voltage (C-V) hysteresis curves and a memory window of 1.2 V with a 5 V writing operation.

  12. Thin films of metal-organic compounds and metal nanoparticle ...

    Indian Academy of Sciences (India)

    Thin films based on two very different metal-organic systems are developed and some nonlinear optical ... capability of the nanoparticle-embedded polymer film is demonstrated. Keywords. Polar crystal; uniaxial ... systems promising candidates for a wide range of electronic, magnetic and optical applications. However ...

  13. Mechanism of metal cationization in organic SIMS

    International Nuclear Information System (INIS)

    Wojciechowski, I.; Delcorte, A.; Gonze, X.; Bertrand, P.

    2003-01-01

    A scenario of metal cationization in which the organic molecule combines with a neutral excited metal atom is proposed. Ionization of the nascent complex occurs via ejection of an electron during the association process. Electron structure calculations for the model systems C 6 H 6 +Me (Me=Ag, Cu, Au) using the density functional theory give a strong argument in favor of the proposed mechanism

  14. Self-Exfoliated Metal-Organic Nanosheets through Hydrolytic Unfolding of Metal-Organic Polyhedra.

    Science.gov (United States)

    Garai, Bikash; Mallick, Arijit; Das, Anuja; Mukherjee, Rabibrata; Banerjee, Rahul

    2017-05-29

    Few-layers thick metal-organic nanosheets have been synthesized using water-assisted solid-state transformation through a combined top-down and bottom-up approach. The metal-organic polyhedra (MOPs) convert into metal-organic frameworks (MOFs) which subsequently self-exfoliate into few-layered metal-organic nanosheets. These MOP crystals experience a hydrophobicity gradient with the inner surface during contact with water because of the existence of hydrophobic spikes on their outer surface. When the amount of water available for interaction is higher, the resultant layers are not stacked to form bulk materials; instead few-layered nanosheets with high uniformity were obtained in high yield. The phenomenon has resulted high yield production of uniformly distributed layered metal-organic nanosheets from three different MOPs, showing its general adaptability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A generalized physiologically-based toxicokinetic modeling system for chemical mixtures containing metals

    OpenAIRE

    Isukapalli Sastry S; Sasso Alan F; Georgopoulos Panos G

    2010-01-01

    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 m...

  16. Enhanced Structural Support of Metal Sites as Nodes in Metal-Organic Frameworks Compared to Metal Complexes

    OpenAIRE

    Das, Sanjit

    2013-01-01

    Metal-organic frameworks are a new class of crystalline, porous solid-state materials with metal ions periodically linked by organic linkers. This gives rise to one-, two- or three-dimensional structures. Here, we compare the stability of similar metal sites toward external ligand (solvent) induced disruption of the coordination environment in metal complexes and in metal-organic frameworks. Our experimental results show that a metal site as node of a metal-organic framework retains much high...

  17. POLAR ORGANIC CHEMICAL INTEGRATIVE SAMPLING ...

    Science.gov (United States)

    The purpose of the research presented in this paper is two-fold: (1) to demonstrate the 4 coupling of two state-of-the-art techniques: a time-weighted polar organic integrative sampler (POCIS) and micro-liquid chromatography-electrospray/ion trap mass spectrometry (u-LC-6 ES/ITMS); and (2) the assessment of these methodologies in a real-world environment -wastewater effluent - for detecting six drugs (four prescription and two illicit). In the effluent from three wastewater treatment plants (WWTP), azithromycin was detected at concentrations ranging from 15ng/L to 66ng/L, equivalent to the total annual release of 0.4 -4 kg into the receiving waters. Detected and confirmed in the effluent from two WWTPs were two illicit drugs methamphetamine and methylenedioxymethamphetamine (MDMA), at 2ng/L and 0.5ng/L, respectively. While the ecotoxicological significance of drugs in environmental matrices, particularly water, has not been closely examined, it can only be surmised that these substances have the potential to adversely affect biota that are continuously exposed to them even at very low levels. The potential for chronic affects on human health is also unknown, but of increasing concern due to the multi use character of water, particularly in densely populated arid areas. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality

  18. Disorder and conductivity of organic metal

    International Nuclear Information System (INIS)

    Bouffard, Serge

    1982-02-01

    At high temperature, quasi-one-dimensional organic conductors are metallic; at low temperature, the electron gas instabilities drive either a metal to insulator transition or a metal to superconductor transition. Precursors of these 3-D ordering could be appear at higher temperature. A study of the effects of irradiation induced defects on a few organic complexes has shown that defects are produced by radiolitic process. Their concentration can be easily deduced from resistivity measurement at room temperature. In the metallic state, the defects act as strong potentials which break the conducting chains and force the electron to jump to the neighbourg stack. The defects produce a mixing between longitudinal and transverse conductivities. While, it is the 3-D effect of the defects which pins the charge density waves and thus the 3-D ordering can not be acheived: the metal to insulator transition is destroyed, the metallic state is stabilized. In the same time, the fluctuative conductivity is suppress. The superconducting regime has been found to be extremely sensitive to irradiation induced defects. Thus we can demonstrate that the 1-D superconducting fluctuations contribute to the conductivity and that the transition temperature is correlated to the 3-D superconducting fluctuations. [fr

  19. Manipulating Light with Transition Metal Clusters, Organic Dyes, and Metal Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Ogut, Serdar [Univ. of Illinois, Chicago, IL (United States)

    2017-09-11

    The primary goals of our research program is to develop and apply state-of-the-art first-principles methods to predict electronic and optical properties of three systems of significant scientific and technological interest: transition metal clusters, organic dyes, and metal-organic frameworks. These systems offer great opportunities to manipulate light for a wide ranging list of energy-related scientific problems and applications. During this grant period, we focused our investigations on the development, implementation, and benchmarking of many-body Green’s function methods (GW approximation and the Bethe-Salpeter equation) to examine excited-state properties of transition metal/transition-metal-oxide clusters and organic molecules that comprise the building blocks of dyes and metal-organic frameworks.

  20. Preparation of silver thin films using liquid-phase precursors by metal organic chemical vapor deposition and their conversion to silver selenide films by selenium vapor deposition

    International Nuclear Information System (INIS)

    Kim, Hong-Ki; Jeong, Han-Cheol; Kim, Kyung Soo; Yoon, Seok Hwan; Lee, Seung Soo; Seo, Kook Won; Shim, Il-Wun

    2005-01-01

    A series of new Ag precursors containing β-diketonate and neutral phosphite ligands were synthesized and characterized by various spectroscopic methods. These volatile precursors in liquid phase were thermally stable and quite useful in the preparation of silver thin films through bubbler-type chemical vapor deposition (CVD). In a typical case of silver (I) 1,1,1-trifluoro-2,4-pentanedionate triethyl phosphite adduct ((tfac)AgP(OEt) 3 ) precursor, very pure silver thin films were obtained under relatively mild conditions without any appreciable amount of F, O, and P impurities. These thin films were easily converted to β-orthorhombic silver selenide by simple selenium vapor deposition method. In scanning electron microscopic analyses, the average particle size of the latter was found to increase to about 1.26 μm after gas-phase selenization reaction

  1. Chemical metallization of KMPR photoresist polymer in aqueous solutions

    Science.gov (United States)

    Zeb, Gul; Duong, Xuan Truong; Vu, Ngoc Pi; Phan, Quang The; Nguyen, Duc Tuong; Ly, Viet Anh; Salimy, Siamak; Le, Xuan Tuan

    2017-06-01

    While conventional methods for preparing thin films of metals and metallic alloys on insulating substrates in the field of microelectromechanical systems (MEMS) include vapor deposition techniques, we demonstrate here that electroless deposition can be considered as an alternate efficient approach to metallize the surface of insulating substrates, such as KMPR epoxy photoresist polymer. In comparison with the physical and chemical vapor deposition methods, which are well-established for metallization of photoresist polymers, our electroless nickel plating requires only immersing the substrates into aqueous solutions in open air at low temperatures. Thin films of nickel alloy have been deposited electrolessly on KMPR surface, through a cost-effective and environmental chromium-free process, mediated through direct grafting of amine palladium complexes in aqueous medium. This covalent organic coating provides excellent adhesion between KMPR and the nickel film and allows better control of the palladium catalyst content. Covalent grafting and characterization of the deposited nickel film have been carried out by means of Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques.

  2. Molecule Matters-Metal Organic Frameworks (MOFs)

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 11. Molecule Matters - Metal Organic Frameworks (MOFs). R Sarvanakumar S Sankararaman ... Author Affiliations. R Sarvanakumar1 S Sankararaman1. Department of Chemistry, Indian Institute of Technology, Madras, Chennai 600036, India.

  3. Metal Organic Framework: Crystalline Stacked Molecular Containers

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 12. Metal Organic Framework: ... Ramanathan Vaidhyanathan. General Article Volume 19 Issue 12 December 2014 pp 1147-1157 ... Vaidhyanathan1. Department of Chemistry Indian Institute of Science Education and Research Pune, India.

  4. The relevance of metal organic frameworks (MOFs)

    Indian Academy of Sciences (India)

    The metal organic frameworks (MOFs) have evolved to be an important family and a corner stone for research in the area of inorganic chemistry. The progress made since 2000 has attracted researchers from other disciplines to actively engage themselves in this area. This cooperative synergy of different scientific believes ...

  5. Magnetic behaviour in metal-organic frameworks

    Indian Academy of Sciences (India)

    The article describes the synthesis, structure and magnetic investigations of a series of metal-organic framework compounds formed with Mn+2 and Ni+2 ions. The structures, determined using the single crystal X-ray diffraction, indicated that the structures possess two- and three-dimensional structures with magnetically ...

  6. A topological approach to chemical organizations.

    Science.gov (United States)

    Benkö, Gil; Centler, Florian; Dittrich, Peter; Flamm, Christoph; Stadler, Bärbel M R; Stadler, Peter F

    2009-01-01

    Large chemical reaction networks often exhibit distinctive features that can be interpreted as higher-level structures. Prime examples are metabolic pathways in a biochemical context. We review mathematical approaches that exploit the stoichiometric structure, which can be seen as a particular directed hypergraph, to derive an algebraic picture of chemical organizations. We then give an alternative interpretation in terms of set-valued set functions that encapsulate the production rules of the individual reactions. From the mathematical point of view, these functions define generalized topological spaces on the set of chemical species. We show that organization-theoretic concepts also appear in a natural way in the topological language. This abstract representation in turn suggests the exploration of the chemical meaning of well-established topological concepts. As an example, we consider connectedness in some detail.

  7. Metal-organic chemical vapor deposition of high quality, high indium composition N-polar InGaN layers for tunnel devices

    Science.gov (United States)

    Lund, Cory; Romanczyk, Brian; Catalano, Massimo; Wang, Qingxiao; Li, Wenjun; DiGiovanni, Domenic; Kim, Moon J.; Fay, Patrick; Nakamura, Shuji; DenBaars, Steven P.; Mishra, Umesh K.; Keller, Stacia

    2017-05-01

    In this study, the growth of high quality N-polar InGaN films by metalorganic chemical vapor deposition is presented with a focus on growth process optimization for high indium compositions and the structural and tunneling properties of such films. Uniform InGaN/GaN multiple quantum well stacks with indium compositions up to 0.46 were grown with local compositional analysis performed by energy-dispersive X-ray spectroscopy within a scanning transmission electron microscope. Bright room-temperature photoluminescence up to 600 nm was observed for films with indium compositions up to 0.35. To study the tunneling behavior of the InGaN layers, N-polar GaN/In0.35Ga0.65N/GaN tunnel diodes were fabricated which reached a maximum current density of 1.7 kA/cm2 at 5 V reverse bias. Temperature-dependent measurements are presented and confirm tunneling behavior under reverse bias.

  8. TSCA Chemical Data Reporting Fact Sheet: Reporting Manufactured Chemical Substances from Metal Mining and Related Activities

    Science.gov (United States)

    This fact sheet provides guidance on the Chemical Data Reporting (CDR) rule requirements related to the reporting of mined metals, intermediates, and byproducts manufactured during metal mining and related activities.

  9. Chemical and cellular oxidant production induced by naphthalene secondary organic aerosol (SOA): effect of redox-active metals and photochemical aging.

    Science.gov (United States)

    Tuet, Wing Y; Chen, Yunle; Fok, Shierly; Gao, Dong; Weber, Rodney J; Champion, Julie A; Ng, Nga L

    2017-11-09

    Exposure to air pollution is a leading global health risk. Secondary organic aerosol (SOA) constitute a large portion of ambient particulate matter (PM). In this study, the water-soluble oxidative potential (OP) determined by dithiothreitol (DTT) consumption and intracellular reactive oxygen and nitrogen species (ROS/RNS) production was measured for SOA generated from the photooxidation of naphthalene in the presence of iron sulfate and ammonium sulfate seed particles. The measured intrinsic OP varied for aerosol formed using different initial naphthalene concentrations, however, no trends were observed between OP and bulk aerosol composition or seed type. For all experiments, aerosol generated in the presence of iron-containing seed induced higher ROS/RNS production compared to that formed in the presence of inorganic seed. This effect was primarily attributed to differences in aerosol carbon oxidation state [Formula: see text]. In the presence of iron, radical concentrations are elevated via iron redox cycling, resulting in more oxidized species. An exponential trend was also observed between ROS/RNS and [Formula: see text] for all naphthalene SOA, regardless of seed type or aerosol formation condition. This may have important implications as aerosol have an atmospheric lifetime of a week, over which [Formula: see text] increases due to continued photochemical aging, potentially resulting in more toxic aerosol.

  10. Mechanical Alloying of Metal-Organic Frameworks.

    Science.gov (United States)

    Panda, Tamas; Horike, Satoshi; Hagi, Keisuke; Ogiwara, Naoki; Kadota, Kentaro; Itakura, Tomoya; Tsujimoto, Masahiko; Kitagawa, Susumu

    2017-02-20

    The solvent-free mechanical milling process for two distinct metal-organic framework (MOF) crystals induced the formation of a solid solution, which is not feasible by conventional solution-based syntheses. X-ray and STEM-EDX studies revealed that performing mechanical milling under an Ar atmosphere promotes the high diffusivity of each metal ion in an amorphous solid matrix; the amorphous state turns into the porous crystalline structure by vapor exposure treatment to form a new phase of a MOF solid solution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Control of residual carbon concentration in GaN high electron mobility transistor and realization of high-resistance GaN grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Liu, Z.S.; Chen, P.; Le, L.C.; Yang, J.; Li, X.J. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhang, S.M.; Zhu, J.J.; Wang, H.; Yang, H. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2014-08-01

    GaN films were grown by metal-organic chemical vapor deposition (MOCVD) under various growth conditions. The influences of MOCVD growth parameters, i.e., growth pressure, ammonia (NH{sub 3}) flux, growth temperature, trimethyl-gallium flux and H{sub 2} flux, on residual carbon concentration ([C]) were systematically investigated. Secondary ion mass spectroscopy measurements show that [C] can be effectively modulated by growth conditions. Especially, it can increase by reducing growth pressure up to two orders of magnitude. High-resistance (HR) GaN epilayer with a resistivity over 1.0 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. The mechanism of the formation of HR GaN epilayer is discussed. An Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor structure with a HR GaN buffer layer and an additional low-carbon GaN channel layer is presented, exhibiting a high two dimensional electron gas mobility of 1815 cm{sup 2}/Vs. - Highlights: • Influence of MOCVD parameters on residual carbon concentration in GaN is studied. • GaN layer with a resistivity over 1 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. • High electron mobility transistor (HEMT) structures were prepared. • Control of residual carbon content results in HEMT with high 2-D electron gas mobility.

  12. Pilot-scale electron cyclotron resonance-metal organic chemical vapor deposition system for the preparation of large-area fluorine-doped SnO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Bup Ju [Department of Energy and Environmental Engineering, Shinhan University, 233-1, Sangpae-dong, Dongducheon, Gyeonggi-do 483-777 (Korea, Republic of); Hudaya, Chairul [Department of Electrical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI, Depok 16424 (Indonesia); Center for Energy Convergence, Green City Research Institute, Korea Institute of Science and Technology, Hwarangno 14 gil 5, Seoul 136-791 (Korea, Republic of); Department of Energy and Environmental Engineering, Korea University of Science and Technology, 176 Gajungro Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Lee, Joong Kee, E-mail: leejk@kist.re.kr [Center for Energy Convergence, Green City Research Institute, Korea Institute of Science and Technology, Hwarangno 14 gil 5, Seoul 136-791 (Korea, Republic of); Department of Energy and Environmental Engineering, Korea University of Science and Technology, 176 Gajungro Yuseong-gu, Daejeon 305-350 (Korea, Republic of)

    2016-05-15

    The authors report the surface morphology, optical, electrical, thermal and humidity impacts, and electromagnetic interference properties of fluorine-doped tin oxide (SnO{sub 2}:F or “FTO”) thin films on a flexible polyethylene terephthalate (PET) substrate fabricated by a pilot-scale electron cyclotron resonance–metal organic chemical vapor deposition (PS ECR-MOCVD). The characteristics of large area FTO thin films were compared with a commercially available transparent conductive electrode made of tin-doped indium oxide (ITO), prepared with an identical film and PET thickness of 125 nm and 188 μm, respectively. The results revealed that the as-prepared FTO thin films exhibited comparable performances with the incumbent ITO films, including a high optical transmittance of 97% (substrate-subtracted), low electrical resistivity of about 5 × 10{sup −3} Ω cm, improved electrical and optical performances due to the external thermal and humidity impact, and an excellent shielding effectiveness of electromagnetic interference of nearly 2.3 dB. These excellent performances of the FTO thin films were strongly attributed to the design of the PS ECR-MOCVD, which enabled a uniform plasma environment resulting from a proper mixture of electromagnetic profiles and microwave power.

  13. Organic/metal interfaces. Electronic and structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Duhm, Steffen

    2008-07-17

    measured shift in the vacuum level between monolayer and multilayer coverage was direct evidence for thermodynamically driven charge transfer between molecular layers. (iv) A clear correlation between the strength of chemical bonding of COMs and the bonding distance to metal substrates could be shown. All these findings lead to a better understanding of organic/metal interface physics and may help to enhance performance of organic devices in the future. (orig.)

  14. Chemical Dynamics at Surfaces of Metal Nanomaterials

    Science.gov (United States)

    2014-07-23

    method to determine 3D molecular structures One of the major problems in experimentally studying heterogeneous catalysis is the lack of tools...the determinations of molecular structures and dynamics on the surfaces of metal nanomaterials – the critical component of heterogeneous catalysts...for the determinations of molecular structures on the surfaces of metal nanomaterials. Practical catalysts, e.g. oxide-supported metal clusters, are

  15. Capture of organic iodides from nuclear waste by metal-organic framework-based molecular traps.

    Science.gov (United States)

    Li, Baiyan; Dong, Xinglong; Wang, Hao; Ma, Dingxuan; Tan, Kui; Jensen, Stephanie; Deibert, Benjamin J; Butler, Joseph; Cure, Jeremy; Shi, Zhan; Thonhauser, Timo; Chabal, Yves J; Han, Yu; Li, Jing

    2017-09-07

    Effective capture of radioactive organic iodides from nuclear waste remains a significant challenge due to the drawbacks of current adsorbents such as low uptake capacity, high cost, and non-recyclability. We report here a general approach to overcome this challenge by creating radioactive organic iodide molecular traps through functionalization of metal-organic framework materials with tertiary amine-binding sites. The molecular trap exhibits a high CH 3 I saturation uptake capacity of 71 wt% at 150 °C, which is more than 340% higher than the industrial adsorbent Ag 0 @MOR under identical conditions. These functionalized metal-organic frameworks also serve as good adsorbents at low temperatures. Furthermore, the resulting adsorbent can be recycled multiple times without loss of capacity, making recyclability a reality. In combination with its chemical and thermal stability, high capture efficiency and low cost, the adsorbent demonstrates promise for industrial radioactive organic iodides capture from nuclear waste. The capture mechanism was investigated by experimental and theoretical methods.Capturing radioactive organic iodides from nuclear waste is important for safe nuclear energy usage, but remains a significant challenge. Here, Li and co-workers fabricate a stable metal-organic framework functionalized with tertiary amine groups that exhibits high capacities for radioactive organic iodides uptake.

  16. Capture of organic iodides from nuclear waste by metal-organic framework-based molecular traps

    KAUST Repository

    Li, Baiyan

    2017-09-01

    Effective capture of radioactive organic iodides from nuclear waste remains a significant challenge due to the drawbacks of current adsorbents such as low uptake capacity, high cost, and non-recyclability. We report here a general approach to overcome this challenge by creating radioactive organic iodide molecular traps through functionalization of metal-organic framework materials with tertiary amine-binding sites. The molecular trap exhibits a high CH3I saturation uptake capacity of 71 wt% at 150 °C, which is more than 340% higher than the industrial adsorbent Ag0@MOR under identical conditions. These functionalized metal-organic frameworks also serve as good adsorbents at low temperatures. Furthermore, the resulting adsorbent can be recycled multiple times without loss of capacity, making recyclability a reality. In combination with its chemical and thermal stability, high capture efficiency and low cost, the adsorbent demonstrates promise for industrial radioactive organic iodides capture from nuclear waste. The capture mechanism was investigated by experimental and theoretical methods.Capturing radioactive organic iodides from nuclear waste is important for safe nuclear energy usage, but remains a significant challenge. Here, Li and co-workers fabricate a stable metal-organic framework functionalized with tertiary amine groups that exhibits high capacities for radioactive organic iodides uptake.

  17. Chemical and Electrochemical Metallic Covering of ABS polymers

    Directory of Open Access Journals (Sweden)

    Florentina Cziple

    2009-10-01

    Full Text Available The aim of this paper is the deposition of metallic layers on the surface of ABS plastic material, by means of two consecutive procedures, namely: the first is represented by the conductibility through chemical or electro-chemical metallic covering of the polymeric support and the second procedure is the electrodeposition of the metal through galvanization. The chemical mehtod consists in the submission of ABS polymers to some conductibility operations of the plastic material surface through chemical copper plating (chemical roughing, degreasing with ultra-sounds, chemical sensitivation, activation and proper conductibility of the material surface. The electrochemical deposition of nickel was made on the plastic material activated in the mixture solution of graphite with potassium carbonate.

  18. Compositions and methods of making and using metal-organic framework compositions

    KAUST Repository

    Mohideen, Mohamed Infas Haja

    2017-05-04

    Embodiments of the present disclosure include a metal-organic framework (MOF) composition comprising one or more metal ions, a plurality of organic ligands, and a solvent, wherein the one or more metal ions associate with the plurality of organic ligands sufficient to form a MOF with kag topology. Embodiments of the present disclosure further include a method of making a MOF composition comprising contacting one or more metal ions with a plurality of organic ligands in the presence of a solvent, sufficient to form a MOF with kag topology, wherein the solvent comprises water only. Embodiments of the present disclosure also describe a method of capturing chemical species from a fluid composition comprising contacting a MOF composition with kag topology and pore size of about 3.4Å to 4.8Å with a fluid composition comprising two or more chemical species and capturing one or more captured chemical species from the fluid composition.

  19. Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

    Energy Technology Data Exchange (ETDEWEB)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin (UC)

    2016-08-30

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  20. Microporous Metal Organic Materials for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    S. G. Sankar; Jing Li; Karl Johnson

    2008-11-30

    We have examined a number of Metal Organic Framework Materials for their potential in hydrogen storage applications. Results obtained in this study may, in general, be summarized as follows: (1) We have identified a new family of porous metal organic framework materials with the compositions M (bdc) (ted){sub 0.5}, {l_brace}M = Zn or Co, bdc = biphenyl dicarboxylate and ted = triethylene diamine{r_brace} that adsorb large quantities of hydrogen ({approx}4.6 wt%) at 77 K and a hydrogen pressure of 50 atm. The modeling performed on these materials agree reasonably well with the experimental results. (2) In some instances, such as in Y{sub 2}(sdba){sub 3}, even though the modeling predicted the possibility of hydrogen adsorption (although only small quantities, {approx}1.2 wt%, 77 K, 50 atm. hydrogen), our experiments indicate that the sample does not adsorb any hydrogen. This may be related to the fact that the pores are extremely small or may be attributed to the lack of proper activation process. (3) Some samples such as Zn (tbip) (tbip = 5-tert butyl isophthalate) exhibit hysteresis characteristics in hydrogen sorption between adsorption and desorption runs. Modeling studies on this sample show good agreement with the desorption behavior. It is necessary to conduct additional studies to fully understand this behavior. (4) Molecular simulations have demonstrated the need to enhance the solid-fluid potential of interaction in order to achieve much higher adsorption amounts at room temperature. We speculate that this may be accomplished through incorporation of light transition metals, such as titanium and scandium, into the metal organic framework materials.

  1. Local Chemical Reactivity of a Metal Alloy Surface

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Scheffler, Matthias

    1995-01-01

    The chemical reactivity of a metal alloy surface is studied by density functional theory investigating the interaction of H2 with NiAl(110). The energy barrier for H2 dissociation is largely different over the Al and Ni sites without, however, reflecting the barriers over the single component metal...

  2. Electronic and chemical structure of metal-silicon interfaces

    Science.gov (United States)

    Grunthaner, P. J.; Grunthaner, F. J.

    1984-01-01

    This paper reviews our current understanding of the near-noble metal silicides and the interfaces formed with Si(100). Using X-ray photoemission spectroscopy, we compare the chemical composition and electronic structure of the room temperature metal-silicon and reacted silicide-silicon interfaces. The relationship between the interfacial chemistry and the Schottky barrier heights for this class of metals on silicon is explored.

  3. Three-dimensional metal-intercalated covalent organic frameworks for near-ambient energy storage

    Science.gov (United States)

    Gao, Fei; Ding, Zijing; Meng, Sheng

    2013-01-01

    A new form of nanoporous material, metal intercalated covalent organic framework (MCOF) is proposed and its energy storage property revealed. Employing density functional and thermodynamical analysis, we find that stable, chemically active, porous materials could form by stacking covalent organic framework (COF) layers with metals as a gluing agent. Metal acts as active sites, while its aggregation is suppressed by a binding energy significantly larger than the corresponding cohesive energy of bulk metals. Two important parameters, metal binding and metal-metal separation, are tuned by selecting suitable building blocks and linkers when constructing COF layers. Systematic searches among a variety of elements and organic molecules identify Ca-intercalated COF with diphenylethyne units as optimal material for H2 storage, reaching a striking gravimetric density ~ 5 wt% at near-ambient conditions (300 K, 20 bar), in comparison to < 0.1 wt% for bare COF-1 under the same condition. PMID:23698018

  4. High-quality uniaxial In(x)Ga(1-x)N/GaN multiple quantum well (MQW) nanowires (NWs) on Si(111) grown by metal-organic chemical vapor deposition (MOCVD) and light-emitting diode (LED) fabrication.

    Science.gov (United States)

    Ra, Yong-Ho; Navamathavan, R; Park, Ji-Hyeon; Lee, Cheul-Ro

    2013-03-01

    This article describes the growth and device characteristics of vertically aligned high-quality uniaxial p-GaN/InxGa1-xN/GaN multiple quantum wells (MQW)/n-GaN nanowires (NWs) on Si(111) substrates grown by metal-organic chemical vapor deposition (MOCVD) technique. The resultant nanowires (NWs), with a diameter of 200-250 nm, have an average length of 2 μm. The feasibility of growing high-quality NWs with well-controlled indium composition MQW structure is demonstrated. These resultant NWs grown on Si(111) substrates were utilized for fabricating vertical-type light-emitting diodes (LEDs). The steep and intense photoluminescence (PL) and cathodoluminescence (CL) spectra are observed, based on the strain-free NWs on Si(111) substrates. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that the MQW NWs are grown along the c-plane with uniform thickness. The current-voltage (I-V) characteristics of these NWs exhibited typical p-n junction LEDs and showed a sharp onset voltage at 2.75 V in the forward bias. The output power is linearly increased with increasing current. The result indicates that the pulsed MOCVD technique is an effective method to grow uniaxial p-GaN/InxGa1-xN/GaN MQW/n-GaN NWs on Si(111), which is more advantageous than other growth techniques, such as molecular beam epitaxy. These results suggest the uniaxial NWs are promising to allow flat-band quantum structures, which can enhance the efficiency of LEDs.

  5. Strain-Compensated InGaAsP Superlattices for Defect Reduction of InP Grown on Exact-Oriented (001 Patterned Si Substrates by Metal Organic Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Ludovico Megalini

    2018-02-01

    Full Text Available We report on the use of InGaAsP strain-compensated superlattices (SC-SLs as a technique to reduce the defect density of Indium Phosphide (InP grown on silicon (InP-on-Si by Metal Organic Chemical Vapor Deposition (MOCVD. Initially, a 2 μm thick gallium arsenide (GaAs layer was grown with very high uniformity on exact oriented (001 300 mm Si wafers; which had been patterned in 90 nm V-grooved trenches separated by silicon dioxide (SiO2 stripes and oriented along the [110] direction. Undercut at the Si/SiO2 interface was used to reduce the propagation of defects into the III–V layers. Following wafer dicing; 2.6 μm of indium phosphide (InP was grown on such GaAs-on-Si templates. InGaAsP SC-SLs and thermal annealing were used to achieve a high-quality and smooth InP pseudo-substrate with a reduced defect density. Both the GaAs-on-Si and the subsequently grown InP layers were characterized using a variety of techniques including X-ray diffraction (XRD; atomic force microscopy (AFM; transmission electron microscopy (TEM; and electron channeling contrast imaging (ECCI; which indicate high-quality of the epitaxial films. The threading dislocation density and RMS surface roughness of the final InP layer were 5 × 108/cm2 and 1.2 nm; respectively and 7.8 × 107/cm2 and 10.8 nm for the GaAs-on-Si layer.

  6. Increasing the Stability of Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Mathieu Bosch

    2014-01-01

    Full Text Available Metal-organic frameworks (MOFs are a new category of advanced porous materials undergoing study by many researchers for their vast variety of both novel structures and potentially useful properties arising from them. Their high porosities, tunable structures, and convenient process of introducing both customizable functional groups and unsaturated metal centers have afforded excellent gas sorption and separation ability, catalytic activity, luminescent properties, and more. However, the robustness and reactivity of a given framework are largely dependent on its metal-ligand interactions, where the metal-containing clusters are often vulnerable to ligand substitution by water or other nucleophiles, meaning that the frameworks may collapse upon exposure even to moist air. Other frameworks may collapse upon thermal or vacuum treatment or simply over time. This instability limits the practical uses of many MOFs. In order to further enhance the stability of the framework, many different approaches, such as the utilization of high-valence metal ions or nitrogen-donor ligands, were recently investigated. This review details the efforts of both our research group and others to synthesize MOFs possessing drastically increased chemical and thermal stability, in addition to exemplary performance for catalysis, gas sorption, and separation.

  7. Metal-contaminated soil remediation by means of paper mill sludges addition: chemical and ecotoxicological evaluation

    International Nuclear Information System (INIS)

    Calace, N.; Campisi, T.; Iacondini, A.; Leoni, M.; Petronio, B.M.; Pietroletti, M.

    2005-01-01

    Metal pollution of soils is a great environmental problem. The major risks due to metal pollution of soil consist of leaching to groundwater and potential toxicity to plants and/or animals. The objective of this study is to evaluate by means of chemical and ecotoxicological approach the effects of paper mill sludge addition on the mobile metal fraction of polluted metal soils. The study was carried out on acidic soil derived from mining activities and thus polluted with heavy metals, and on two paper mill sludges having different chemical features. The results obtained by leaching experiments showed that the addition of a paper mill sludge, consisting mainly of carbonates, silicates and organic matter, to a heavy-metal polluted soil produces a decrease of available metal forms. The carbonate content seems to play a key role in the chemical stabilisation of metals and consequently in a decrease of toxicity of soil. The leached solutions have a non-toxic effect. The mild remediation by addition of sludge has moreover a lasting effect. - Paper mill sludge decreased available metals

  8. Biomimicry in metal-organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, MW; Gu, ZY; Bosch, M; Perry, Z; Zhou, HC

    2015-06-15

    Nature has evolved a great number of biological molecules which serve as excellent constructional or functional units for metal-organic materials (MOMs). Even though the study of biomimetic MOMs is still at its embryonic stage, considerable progress has been made in the past few years. In this critical review, we will highlight the recent advances in the design, development and application of biomimetic MOMs, and illustrate how the incorporation of biological components into MOMs could further enrich their structural and functional diversity. More importantly, this review will provide a systematic overview of different methods for rational design of MOMs with biomimetic features. Published by Elsevier B.V.

  9. Determination of physico-chemical parameters and heavy metals in ...

    African Journals Online (AJOL)

    EJIRO

    Water samples from selected hand-dug wells and Ona River in Itaogbolu area of Akure, Ondo State,. Nigeria were collected, physico-chemical parameters and heavy metals were determined using standard analytical procedure. The results of the physico-chemical analysis were obtained in the following range; PH ...

  10. Assembly, Structure, and Functionality of Metal-Organic Networks and Organic Semiconductor Layers at Surfaces

    Science.gov (United States)

    Tempas, Christopher D.

    Self-assembled nanostructures at surfaces show promise for the development of next generation technologies including organic electronic devices and heterogeneous catalysis. In many cases, the functionality of these nanostructures is not well understood. This thesis presents strategies for the structural design of new on-surface metal-organic networks and probes their chemical reactivity. It is shown that creating uniform metal sites greatly increases selectivity when compared to ligand-free metal islands. When O2 reacts with single-site vanadium centers, in redox-active self-assembled coordination networks on the Au(100) surface, it forms one product. When O2 reacts with vanadium metal islands on the same surface, multiple products are formed. Other metal-organic networks described in this thesis include a mixed valence network containing Pt0 and PtII and a network where two Fe centers reside in close proximity. This structure is stable to temperatures >450 °C. These new on-surface assemblies may offer the ability to perform reactions of increasing complexity as future heterogeneous catalysts. The functionalization of organic semiconductor molecules is also shown. When a few molecular layers are grown on the surface, it is seen that the addition of functional groups changes both the film's structure and charge transport properties. This is due to changes in both first layer packing structure and the pi-electron distribution in the functionalized molecules compared to the original molecule. The systems described in this thesis were studied using high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy. Overall, this work provides strategies for the creation of new, well-defined on-surface nanostructures and adds additional chemical insight into their properties.

  11. Thin metal electrodes for semitransparent organic photovoltaics

    KAUST Repository

    Lee, Kyusung

    2013-08-01

    We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100 mW/cm2 with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers. © 2013 ETRI.

  12. Modeling global persistent organic chemicals in clouds

    Science.gov (United States)

    Mao, Xiaoxuan; Gao, Hong; Huang, Tao; Zhang, Lisheng; Ma, Jianmin

    2014-10-01

    A cloud model was implemented in a global atmospheric transport model to simulate cloud liquid water content and quantify the influence of clouds on gas/aqueous phase partitioning of persistent organic chemicals (POCs). Partitioning fractions of gas/aqueous and particle phases in clouds for three POCs α-hexachlorocyclohexane (α-HCH), polychlorinated biphenyl-28 (PCB-28), and PCB-138 in a cloudy atmosphere were estimated. Results show that the partition fraction of these selected chemicals depend on cloud liquid water content (LWC) and air temperature. We calculated global distribution of water droplet/ice particle-air partitioning coefficients of the three chemicals in clouds. The partition fractions at selected model grids in the Northern Hemisphere show that α-HCH, a hydrophilic chemical, is sorbed strongly onto cloud water droplets. The computed partition fractions at four selected model grids show that α-HCH tends to be sorbed onto clouds over land (source region) from summer to early fall, and over ocean from late spring to early fall. 20-60% of α-HCH is able to be sorbed to cloud waters over mid-latitude oceans during summer days. PCB-138, one of hydrophobic POCs, on the other hand, tends to be sorbed to particles in the atmosphere subject to air temperature. We also show that, on seasonal or annual average, 10-20% of averaged PCB-28 over the Northern Hemisphere could be sorbed onto clouds, leading to reduction of its gas-phase concentration in the atmosphere.

  13. TMVOC, simulator for multiple volatile organic chemicals

    International Nuclear Information System (INIS)

    Pruess, Karsten; Battistelli, Alfredo

    2003-01-01

    TMVOC is a numerical simulator for three-phase non-isothermal flow of water, soil gas, and a multicomponent mixture of volatile organic chemicals (VOCs) in multidimensional heterogeneous porous media. It is an extension of the TOUGH2 general-purpose simulation program developed at the Lawrence Berkeley National Laboratory. TMVOC is designed for applications to contamination problems that involve hydrocarbon fuel or organic solvent spills in saturated and unsaturated zones. It can model contaminant behavior under ''natural'' environmental conditions, as well as for engineered systems, such as soil vapor extraction, groundwater pumping, or steam-assisted source remediation. TMVOC is upwards compatible with T2VOC (Falta et al., 1995) and can be initialized from T2VOC-style initial conditions. The main enhancements in TMVOC relative to T2VOC are as follows: a multicomponent mixture of volatile organic chemicals can be modeled; any and all combinations of the three phases water-oil-gas are treated; several non-condensible gases may be present; diffusion is treated in all phases in a manner that is fully coupled with phase partitioning. This paper gives a brief summary of the methodology used in TMVOC as well as highlighting some implementation issues. Simulation of a NAPL spill and subsequent remediation is discussed for a 2-D vertical section of a saturated-unsaturated flow problem

  14. Transition metal complexes supported on metal-organic frameworks for heterogeneous catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Farha, Omar K.; Hupp, Joseph T.; Delferro, Massimiliano; Klet, Rachel C.

    2017-02-07

    A robust mesoporous metal-organic framework comprising a hafnium-based metal-organic framework and a single-site zirconium-benzyl species is provided. The hafnium, zirconium-benzyl metal-organic framework is useful as a catalyst for the polymerization of an alkene.

  15. Metal-organic framework materials with ultrahigh surface areas

    Science.gov (United States)

    Farha, Omar K.; Hupp, Joseph T.; Wilmer, Christopher E.; Eryazici, Ibrahim; Snurr, Randall Q.; Gomez-Gualdron, Diego A.; Borah, Bhaskarjyoti

    2015-12-22

    A metal organic framework (MOF) material including a Brunauer-Emmett-Teller (BET) surface area greater than 7,010 m.sup.2/g. Also a metal organic framework (MOF) material including hexa-carboxylated linkers including alkyne bond. Also a metal organic framework (MOF) material including three types of cuboctahedron cages fused to provide continuous channels. Also a method of making a metal organic framework (MOF) material including saponifying hexaester precursors having alkyne bonds to form a plurality of hexa-carboxylated linkers including alkyne bonds and performing a solvothermal reaction with the plurality of hexa-carboxylated linkers and one or more metal containing compounds to form the MOF material.

  16. Metal nano-film resistivity chemical sensor.

    Science.gov (United States)

    Podešva, Pavel; Foret, František

    2016-02-01

    In this work, we present a study on reusable thin metal film resistivity-based sensor for direct measurement of binding of thiol containing molecules in liquid samples. While in bulk conductors the DC current is not influenced by the surface events to a measureable degree in a thin metal layer the electrons close to the surface conduct a significant part of electricity and are influenced by the surface interactions. In this study, the thickness of the gold layer was kept below 100 nm resulting in easily measureable resistivity changes of the metal element upon a surface SH-groups binding. No further surface modifications were necessary. Thin film gold layers deposited on a glass substrate by vacuum sputtering were photolithographically structured into four sensing elements arranged in a Wheatstone bridge to compensate for resistance fluctuations due to the temperature changes. Concentrations as low 100 pM provided measureable signals. The surface after the measurement could be electrolytically regenerated for next measurements. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Elimination kinetic model for organic chemicals in earthworms.

    NARCIS (Netherlands)

    Dimitrova, N.; Dimitrov, S.; Georgieva, D.; van Gestel, C.A.M.; Hankard, P.; Spurgeon, D.J.; Li, H.; Mekenyan, O.

    2010-01-01

    Mechanistic understanding of bioaccumulation in different organisms and environments should take into account the influence of organism and chemical depending factors on the uptake and elimination kinetics of chemicals. Lipophilicity, metabolism, sorption (bioavailability) and biodegradation of

  18. Hydrogen Storage in Metal-Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-04-28

    The design and characterization of new materials for hydrogen storage is an important area of research, as the ability to store hydrogen at lower pressures and higher temperatures than currently feasible would lower operating costs for small hydrogen fuel cell vehicles. In particular, metal-organic frameworks (MOFs) represent promising materials for use in storing hydrogen in this capacity. MOFs are highly porous, three-dimensional crystalline solids that are formed via linkages between metal ions (e.g., iron, nickel, and zinc) and organic molecules. MOFs can store hydrogen via strong adsorptive interactions between the gas molecules and the pores of the framework, providing a high surface area for gas adsorption and thus the opportunity to store hydrogen at significantly lower pressures than with current technologies. By lowering the energy required for hydrogen storage, these materials hold promise in rendering hydrogen a more viable fuel for motor vehicles, which is a highly desirable outcome given the clean nature of hydrogen fuel cells (water is the only byproduct of combustion) and the current state of global climate change resulting from the combustion of fossil fuels. The work presented in this report is the result of collaborative efforts between researchers at Lawrence Berkeley National Lab (LBNL), the National Institute of Standards and Technology (NIST), and General Motors Corporation (GM) to discover novel MOFs promising for H2 storage and characterize their properties. Described herein are several new framework systems with improved gravimetric and volumetric capacity to strongly bind H2 at temperatures relevant for vehicle storage. These materials were rigorously characterized using neutron diffraction, to determine the precise binding locations of hydrogen within the frameworks, and high-pressure H2 adsorption measurements, to provide a comprehensive picture of H2 adsorption at all relevant pressures. A

  19. Controlling the magnetism of adsorbed metal-organic molecules.

    Science.gov (United States)

    Kuch, Wolfgang; Bernien, Matthias

    2017-01-18

    Gaining control on the size or the direction of the magnetic moment of adsorbed metal-organic molecules constitutes an important step towards the realization of a surface-mounted molecular spin electronics. Such control can be gained by taking advantage of interactions of the molecule's magnetic moment with the environment. The paramagnetic moments of adsorbed metal-organic molecules, for example, can be controlled by the interaction with magnetically ordered substrates. Metalloporphyrins and -phthalocyanines display a quasi-planar geometry, allowing the central metal ion to interact with substrate electronic states. This can lead to magnetic coupling with a ferromagnetic or even antiferromagnetic substrate. The molecule-substrate coupling can be mediated and controlled by insertion layers such as oxygen atoms, graphene, or nonmagnetic metal layers. Control on the magnetic properties of adsorbed metalloporphyrins or -phthalocyanines can also be gained by on-surface chemical modification of the molecules. The magnetic moment or the magnetic coupling to ferromagnetic substrates can be changed by adsorption and thermal desorption of small molecules that interact with the fourfold-coordinated metal center via the remaining axial coordination site. Spin-crossover molecules, which possess a metastable spin state that can be switched by external stimuli such as temperature or light, are another promising class of candidates for control of magnetic properties. However, the immobilization of such molecules on a solid surface often results in a quench of the spin transition due to the interaction with the substrate. We present examples of Fe(II) spin-crossover complexes in direct contact with a solid surface that undergo a reversible spin-crossover transition as a function of temperature, by illumination with visible light, or can be switched by the tip of a scanning tunneling microscope.

  20. Templated synthesis, postsynthetic metal exchange, and properties of a porphyrin-encapsulating metal-organic material

    KAUST Repository

    Zhang, ZhenJie

    2012-01-18

    Reaction of biphenyl-3,4′,5-tricarboxylate (H 3BPT) and CdCl 2 in the presence of meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate (TMPyP) afforded porph@MOM-10, a microporous metal-organic material containing CdTMPyP cations encapsulated in an anionic Cd(II) carboxylate framework, [Cd 6(BPT) 4Cl 4(H 2O) 4]. Porph@MOM-10 is a versatile platform that undergoes exchange to serve as the parent of a series of porph@MOMs that exhibit permanent porosity and heterogeneous catalytic activity. © 2011 American Chemical Society.

  1. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    (figure 7). We have also been able to bond Al2O3 to graphene by using AlCl3 as the reactant. The oxide film was amor- phous after calcination at 600. ◦. C. We have prepared chemically bonded magnetic Fe3O4 nanoparticles to graphene by functionalizing Fe3O4 by amine, then reacting it with graphene functionalized with.

  2. Sorption of heavy metal ions on new metal-ligand complexes chemically derived from Lycopodium clavatum

    Energy Technology Data Exchange (ETDEWEB)

    Pehlivan, E.; Ersoz, M.; Yildiz, S. [Univ. of Selcuk, Konya (Turkey); Duncan, H.J. [Univ. of Glasgow, Scotland (United Kingdom)

    1994-08-01

    Sorption of heavy metal ions from aqueous solution has been investigated as a function of pH using a novel exchanger system whereby Lycopodium clavatum is functionalized with carboxylate and glyoxime metal-ligand complexes. The new ligand exchangers were prepared using a reaction of diaminosporopollenin with various metal-ligand complexes of glyoxime and monocarboxylic acid. The sorptive behavior of these metal-ligand exchangers and the possibilities to remove and to recover selectively heavy metal cations using these systems are discussed on the basis of their chemical natures and their complexing properties.

  3. Organic modification of metal / semiconductor Schottky contacts

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Pinzon, H.A.

    2006-07-10

    In the present work a Metal / organic / inorganic semiconductor hybrid heterostructure (Ag / DiMe-PTCDI / GaAs) was built under UHV conditions and characterised in situ. The aim was to investigate the influence of the organic layer in the surface properties of GaAs(100) and in the electrical response of organic-modified Ag / GaAs Schottky diodes. The device was tested by combining surface-sensitive techniques (Photoemission spectroscopy and NEXAFS) with electrical measurements (current-voltage, capacitance-voltage, impedance and charge transient spectroscopies). Core level examination by PES confirms removal of native oxide layers on sulphur passivated (S-GaAs) and hydrogen plasma treated GaAs(100) (H+GaAs) surfaces. Additional deposition of ultrathin layers of DiMe-PTCDI may lead to a reduction of the surface defects density and thereby to an improvement of the electronic properties of GaAs. The energy level alignment through the heterostructure was deduced by combining UPS and I-V measurements. This allows fitting of the I-V characteristics with electron as majority carriers injected over a barrier by thermionic emission as a primary event. For thin organic layers (below 8 nm thickness) several techniques (UPS, I-V, C-V, QTS and AFM) show non homogeneous layer growth, leading to formation of voids. The coverage of the H+GaAs substrate as a function of the nominal thickness of DiMe-PTCDI was assessed via C-V measurements assuming a voltage independent capacitance of the organic layer. The frequency response of the device was evaluated through C-V and impedance measurements in the range 1 kHz-1 MHz. The almost independent behaviour of the capacitance in the measured frequency range confirmed the assumption of a near geometrical capacitor, which was used for modelling the impedance with an equivalent circuit of seven components. From there it was found a predominance of the space charge region impedance, so that A.C. conduction can only takes place through the

  4. Dual Mechanism Nonlinear Response of Selected Metal Organic Chromophores

    National Research Council Canada - National Science Library

    Peak, John D

    2007-01-01

    13 The goal for the research described herein is the development of a series of transition metal based metal organic chromophores that display both two-photon and excited state absorption (TPA/ESA) character...

  5. Melt-quenched glasses of metal-organic frameworks

    DEFF Research Database (Denmark)

    Bennett, T.D.; Yue, Yuanzheng; Li, P.

    2016-01-01

    Crystalline solids dominate the field of metal−organic frameworks (MOFs), with access to the liquid and glass states of matter usually prohibited by relatively low temperatures of thermal decomposition. In this work, we give due consideration to framework chemistry and topology to expand...... of other MOFs. The glasses formed upon vitrification are chemically and structurally distinct from the three other existing categories of melt-quenched glasses (inorganic nonmetallic, organic, and metallic), and retain the basic metal−ligand connectivity of crystalline MOFs, which connects their mechanical...... the phenomenon of the melting of 3D MOFs, linking crystal chemistry to framework melting temperature and kinetic fragility of the glass-forming liquids. Here we show that melting temperatures can be lowered by altering the chemistry of the crystalline MOF state, which provides a route to facilitate the melting...

  6. The compositional, structural, and magnetic properties of a Fe{sub 3}O{sub 4}/Ga{sub 2}O{sub 3}/GaN spin injecting hetero-structure grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhonghua; Huang, Shimin [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Tang, Kun, E-mail: ktang@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Gu, Shulin, E-mail: slgu@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Zhu, Shunming [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Ye, Jiandong [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Nanjing University Institute of Optoelectronics at Yangzhou, Yangzhou 225009 (China); Xu, Mingxiang [Department of Physics, Southeast University, Nanjing 210096 (China); Wang, Wei; Zheng, Youdou [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China)

    2016-12-01

    Highlights: • The Fe{sub 3}O{sub 4}/Ga{sub 2}O{sub 3}/GaN hetero-structure has been fabricated by MOCVD successfully. • The formation mechanism of different layers in sample was revealed in details. • The properties of the hetero-structure have been presented and discussed extensively. • The effect of Ga diffusion on the magnetic properties of Fe{sub 3}O{sub 4} film has been shown. - Abstract: In this article, the authors have designed and fabricated a Fe{sub 3}O{sub 4}/Ga{sub 2}O{sub 3}/GaN spin injecting hetero-structure by metal-organic chemical vapor deposition. The compositional, structural, and magnetic properties of the hetero-structure have been characterized and discussed. From the characterizations, the hetero-structure has been successfully grown generally. However, due to the unintentional diffusion of Ga ions from Ga{sub 2}O{sub 3}/GaN layers, the most part of the nominal Fe{sub 3}O{sub 4} layer is actually in the form of Ga{sub x}Fe{sub 3−x}O{sub 4} with gradually decreased x values from the Fe{sub 3}O{sub 4}/Ga{sub 2}O{sub 3} interface to the Fe{sub 3}O{sub 4} surface. Post-annealing process can further aggravate the diffusion. Due to the similar ionic radius of Ga and Fe, the structural configuration of the Ga{sub x}Fe{sub 3−x}O{sub 4} does not differ from that of pure Fe{sub 3}O{sub 4}. However, the ferromagnetism has been reduced with the incorporation of Ga into Fe{sub 3}O{sub 4}, which has been explained by the increased Yafet-Kittel angles in presence of considerable amount of Ga incorporation. A different behavior of the magnetoresistance has been found on the as-grown and annealed samples, which could be modelled and explained by the competition between the spin-dependent and spin-independent conduction channels. This work has provided detailed information on the interfacial properties of the Fe{sub 3}O{sub 4}/Ga{sub 2}O{sub 3}/GaN spin injecting hetero-structure, which is the solid basis for further improvement and application of

  7. Microstructural and superconducting properties of high current metal-organic chemical vapor deposition YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} coated conductor wires

    Energy Technology Data Exchange (ETDEWEB)

    Holesinger, T G; Maiorov, B; Ugurlu, O; Civale, L [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Chen, Y; Xiong, X; Xie, Y; Selvamanickam, V [SuperPower, Inc., Schenectady, NY 12304 (United States)

    2009-04-15

    Metal-organic chemical vapor deposition (MOCVD) on flexible, ion beam assisted deposition MgO templates has been used to produce high critical current density (J{sub c}) (Y,Sm){sub 1}Ba{sub 2}Cu{sub 3}O{sub y} (REBCO) films suitable for use in producing practical high temperature superconducting (HTS) coated conductor wires. Thick films on tape were produced with sequential additions of 0.7 {mu}m of REBCO via a reel-to-reel progression through a custom-designed MOCVD reactor. Multi-pass processing for thick film deposition is critically dependent upon minimizing surface secondary phase formation. Critical currents (I{sub c}s) of up to 600 A/cm width (t = 2.8 {mu}m, J{sub c} = 2.6 MA cm{sup -2}, 77 K, self-field) were obtained in short lengths of HTS wires. These high performance MOCVD films are characterized by closely spaced (Y,Sm){sub 2}O{sub 3} nanoparticle layers that may be tilted relative to the film normal and REBCO orientation. Small shifts in the angular dependence of J{sub c} in low and intermediate applied magnetic fields can be associated with the tilted nanoparticle layers. Also present in these films were YCuO{sub 2} nanoplates aligned with the YBCO matrix (short dimension perpendicular to the film normal), threading dislocations, and oriented composite defects (OCDs). The latter structures consist of single or multiple a-axis oriented grains coated on each side with insulating (Y,Sm){sub 2}O{sub 3} or CuO. The OCDs formed a connected network of insulating phases by the end of the fourth pass. Subsequent attempts at adding additional layers did not increase I{sub c}. There is an inconsistency between the measured J{sub c} and the observed microstructural degradation that occurs with each additional layer, suggesting that previously deposited layers are improving with each repeated reactor pass. These dynamic changes suggest a role for post-processing to optimize superconducting properties of as-deposited films, addressing issues associated with

  8. Tri-metallic ferrite oxygen carriers for chemical looping combustion

    Science.gov (United States)

    Siriwardane, Ranjani V.; Fan, Yueying

    2017-10-25

    The disclosure provides a tri-metallic ferrite oxygen carrier for the chemical looping combustion of carbonaceous fuels. The tri-metallic ferrite oxygen carrier comprises Cu.sub.xFe.sub.yMn.sub.zO.sub.4-.delta., where Cu.sub.xFe.sub.yMn.sub.zO.sub.4-.delta. is a chemical composition. Generally, 0.5.ltoreq.x.ltoreq.2.0, 0.2.ltoreq.y.ltoreq.2.5, and 0.2.ltoreq.z.ltoreq.2.5, and in some embodiments, 0.8.ltoreq.x.ltoreq.1.2, y.ltoreq.1.2, and z.gtoreq.0.8. The tri-metallic ferrite oxygen carrier may be used in various applications for the combustion of carbonaceous fuels, including as an oxygen carrier for chemical looping combustion.

  9. Metal-adeninate vertices for the construction of an exceptionally porous metal-organic framework.

    Science.gov (United States)

    An, Jihyun; Farha, Omar K; Hupp, Joseph T; Pohl, Ehmke; Yeh, Joanne I; Rosi, Nathaniel L

    2012-01-03

    Metal-organic frameworks comprising metal-carboxylate cluster vertices and long, branched organic linkers are the most porous materials known, and therefore have attracted tremendous attention for many applications, including gas storage, separations, catalysis and drug delivery. To increase metal-organic framework porosity, the size and complexity of linkers has increased. Here we present a promising alternative strategy for constructing mesoporous metal-organic frameworks that addresses the size of the vertex rather than the length of the organic linker. This approach uses large metal-biomolecule clusters, in particular zinc-adeninate building units, as vertices to construct bio-MOF-100, an exclusively mesoporous metal-organic framework. Bio-MOF-100 exhibits a high surface area (4,300 m(2) g(-1)), one of the lowest crystal densities (0.302 g cm(-3)) and the largest metal-organic framework pore volume reported to date (4.3 cm(3) g(-1)).

  10. Metal-Organic Nanosheets Formed via Defect-Mediated Transformation of a Hafnium Metal-Organic Framework.

    Science.gov (United States)

    Cliffe, Matthew J; Castillo-Martínez, Elizabeth; Wu, Yue; Lee, Jeongjae; Forse, Alexander C; Firth, Francesca C N; Moghadam, Peyman Z; Fairen-Jimenez, David; Gaultois, Michael W; Hill, Joshua A; Magdysyuk, Oxana V; Slater, Ben; Goodwin, Andrew L; Grey, Clare P

    2017-04-19

    We report a hafnium-containing MOF, hcp UiO-67(Hf), which is a ligand-deficient layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its lower ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed "double cluster" (Hf 12 O 8 (OH) 14 ), analogous to the condensation of coordination polyhedra in oxide frameworks. In oxide frameworks, variable stoichiometry can lead to more complex defect structures, e.g., crystallographic shear planes or modules with differing compositions, which can be the source of further chemical reactivity; likewise, the layered hcp UiO-67 can react further to reversibly form a two-dimensional metal-organic framework, hxl UiO-67. Both three-dimensional hcp UiO-67 and two-dimensional hxl UiO-67 can be delaminated to form metal-organic nanosheets. Delamination of hcp UiO-67 occurs through the cleavage of strong hafnium-carboxylate bonds and is effected under mild conditions, suggesting that defect-ordered MOFs could be a productive route to porous two-dimensional materials.

  11. Modeling the role of microplastics in Bioaccumulation of organic chemicals to marine aquatic organisms. Critical Review

    NARCIS (Netherlands)

    Koelmans, A.A.

    2015-01-01

    It has been shown that ingestion of microplastics may increase bioaccumulation of organic chemicals by aquatic organisms. This paper critically reviews the literature on the effects of plastic ingestion on the bioaccumulation of organic chemicals, emphasizing quantitative approaches and mechanistic

  12. Zeolite-like metal-organic frameworks with ana topology

    KAUST Repository

    Eddaoudi, Mohamed

    2017-04-20

    Embodiments of the present disclosure describe a zeolite-like metal-organic framework composition comprising a metal-organic framework composition with ana topology characterized by the formula [MIII(4, 5-imidazole dicarboxylic acid)2X(solvent)a]n wherein MIII comprises a trivalent cation of a rare earth element, X comprises an alkali metal element or alkaline earth metal element, and solvent comprises a guest molecule occupying pores. Embodiments of the present disclosure describe a method of separating paraffins comprising contacting a zeolite-like metal-organic framework with ana topology with a flow of paraffins, and separating the paraffins by size.

  13. Metal-organic frameworks: structure, properties, methods of synthesis and characterization

    International Nuclear Information System (INIS)

    Butova, V V; Soldatov, M A; Guda, A A; Lomachenko, K A; Lamberti, C

    2016-01-01

    This review deals with key methods of synthesis and characterization of metal-organic frameworks (MOFs). The modular structure affords a wide variety of MOFs with different active metal sites and organic linkers. These compounds represent a new stage of development of porous materials in which the pore size and the active site structure can be modified within wide limits. The set of experimental methods considered in this review is sufficient for studying the short-range and long-range order of the MOF crystal structure, determining the morphology of samples and elucidating the processes that occur at the active metal site in the course of chemical reactions. The interest in metal-organic frameworks results, first of all, from their numerous possible applications, ranging from gas separation and storage to chemical reactions within the pores. The bibliography includes 362 references

  14. Chemical compatibility of structural materials in alkali metals

    International Nuclear Information System (INIS)

    Natesan, K.; Rink, D.L.; Haglund, R.

    1995-01-01

    The objectives of this task are to (a) evaluate the chemical compatibility of structural alloys such as V-5 wt.%Cr-5 wt.%Ti alloy and Type 316 stainless steel for application in liquid alkali metals such as lithium and sodium-78 wt.% potassium (NaK) at temperatures in the range that are of interest for International Thermonuclear Experimental Reactor (ITER); (b) evaluate the transfer of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen between structural materials and liquid metals; and (c) evaluate the effects of such transfers on the mechanical and microstructural characteristics of the materials for long-term service in liquid-metal-environments

  15. Removal of heavy metal ions from wastewater by chemically modified plant wastes as adsorbents: a review.

    Science.gov (United States)

    Wan Ngah, W S; Hanafiah, M A K M

    2008-07-01

    The application of low-cost adsorbents obtained from plant wastes as a replacement for costly conventional methods of removing heavy metal ions from wastewater has been reviewed. It is well known that cellulosic waste materials can be obtained and employed as cheap adsorbents and their performance to remove heavy metal ions can be affected upon chemical treatment. In general, chemically modified plant wastes exhibit higher adsorption capacities than unmodified forms. Numerous chemicals have been used for modifications which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. In this review, an extensive list of plant wastes as adsorbents including rice husks, spent grain, sawdust, sugarcane bagasse, fruit wastes, weeds and others has been compiled. Some of the treated adsorbents show good adsorption capacities for Cd, Cu, Pb, Zn and Ni.

  16. Preparation, Characterization, and Postsynthetic Modification of Metal-Organic Frameworks: Synthetic Experiments for an Undergraduate Laboratory Course in Inorganic Chemistry

    Science.gov (United States)

    Sumida, Kenji; Arnold, John

    2011-01-01

    Metal-organic frameworks (MOFs) are crystalline materials that are composed of an infinite array of metal nodes (single ions or clusters) linked to one another by polyfunctional organic compounds. Because of their extraordinary surface areas and high degree of control over the physical and chemical properties, these materials have received much…

  17. Metal ion sorption by untreated and chemically treated biomass

    Energy Technology Data Exchange (ETDEWEB)

    Kilbane, J.J.; Xie, J.

    1992-12-31

    The metal-binding ability of biosorbents is well known; however, in comparison with commercial ion-exchange resins the capacity of biosorbents is low. The purpose of this research was to examine chemically modified biosorbents and biosorbents prepared from microorganisms isolated from extreme environments to determine if significant improvements in metal-binding capacity or biosorbents with unique capabilities could be produced. Chemical treatments examined included acid, alkali, carbon disulfide, phosphorus oxychloride, anhydrous formamide, sodium thiosulfate, sodium chloroacetic acid, and phenylsulfonate. Biosorbents were prepared from microorganisms isolated from pristine and acid mine drainage impacted sites and included heterotrophs, methanotrophs, algae, and sulfate reducers. Chemical modification with carbon disulfide, phosphorous oxychloride, and sodium thiosulfate yielded biosorbents with such as much as 74%, 133%, and 155% improvements, respectively, in metal-binding capacity, but the performance of these chemically modified biosorbents deteriorated upon repeated use. A culture isolated from an acid mine drainage impacted site, IGTM17, exhibits about 3-fold higher metal-binding capacity in comparison with other biosorbents examined in this study. IGTM17 also exhibits superior metal-binding ability at decreased pH or in the presence of interfering common cations in comparison with other biosorbents or some commercially available cation exchange resins. Some biosorbents, such as IGTM5, can bind anions. To our knowledge this is the first demonstration of the ability of biosorbents to bind anions. Moreover, preliminary data indicate that the chemical modification of biosorbents may be capable of imparting the ability to selectively bind certain anions. Further research is needed to optimize conditions for the chemical modification and stabilization of biosorbents.

  18. Effect of plants on the bioavailability of metals and other chemical properties of biosolids in a column study.

    Science.gov (United States)

    Huynh, Trang T; Laidlaw, W Scott; Singh, Balwant; Zhang, Hao; Baker, Alan J M

    2012-10-01

    The effects of metal-accumulating plants (Salix x reichardtii and Populus balsamifera) on the chemical properties and dynamics of metals in biosolids were investigated using different techniques including diffusive gradients in thin films (DGT), sequential extraction procedures and partitioning coefficient (K(d)). Plants could effectively extract Cd, Ni, and Zn and decreased dissolved organic carbon (DOC). The presence of plants increased the potential bioavailability of these metals, as assessed by an increase in the ratio of metal measured by DGT and metals in the solution. The plants affected the Cd, Ni, and Zn pools (soluble/exchangeable; Fe/Mn oxide and organic matter bound) characterised by sequential extraction and K(d) but did not reduce the total metals in either substrate. However, plants had no effect on Cu, presumably because of the effective buffering of available Cu by organic matter in both solution and solid phases. A high density of plant roots was associated with increased leaching of metals.

  19. A metal-free organic-inorganic aqueous flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Huskinson, B; Marshak, MP; Suh, C; Er, S; Gerhardt, MR; Galvin, CJ; Chen, XD; Aspuru-Guzik, A; Gordon, RG; Aziz, MJ

    2014-01-08

    As the fraction of electricity generation from intermittent renewable sources-such as solar or wind-grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output(1,2). In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form(3-5). Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts(6,7). Here we describe a class of energy storage materials that exploits the favourable chemical and electro-chemical properties of a family of molecules known as quinones. The example we demonstrate is ametal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br-2/Br- redox couple, yields a peak galvanic power density exceeding 0.6 W cm(-2) at 1.3 A cm(-2). Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals(8). This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of p-aromatic redox-active organic molecules instead of redox-active metals

  20. Chemical Speciation of Some metal ions in Groundwaters of Yola ...

    African Journals Online (AJOL)

    Chemical speciation of some metal ions in groundwaters of Yola area using geochemical model were carried out to determine the water quality of the area using the PHREEQC speciation model. The study findings based on model calculations indicated that free Na+, Ca2+, Mg2+ and K+ ions are present and the ...

  1. Physico-chemical characteristics and Heavy metal levels in Drinking ...

    African Journals Online (AJOL)

    Physico-chemical characteristics and Heavy metal levels in Drinking Water sources in Sokoto metropolis in North-western Nigeria. ... Tap water samples had similar conductivity values (180 -190μS/m), sachet water samples had conductivity values ranging from 80μS/m to 260μS/m while well water samples had highest ...

  2. Determination of physico-chemical parameters and heavy metals in ...

    African Journals Online (AJOL)

    EJIRO

    Full Length Research Paper. Determination of physico-chemical parameters and heavy metals in water samples from Itaogbolu area of. Ondo-State, Nigeria. S. O. Adefemi* and E. E. Awokunmi. Department of Chemistry, University of Ado Ekiti, P. M. B. 5363, Nigeria. Accepted 22 December, 2009. Water samples from ...

  3. Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Henych, Jiří; Janos, P.; Skoumal, M.

    2016-01-01

    Roč. 236, č. 2016 (2016), s. 239-258 ISSN 0179-5953 R&D Projects: GA ČR(CZ) GAP106/12/1116 Institutional support: RVO:61388980 Keywords : chemical warfare agent * metal nanoparticle * unique surface-chemistry * mesoporous manganese oxide Subject RIV: CA - Inorganic Chemistry Impact factor: 3.930, year: 2016

  4. Chemical Abundances of Metal-poor stars in Dwarf Galaxies

    NARCIS (Netherlands)

    Venn, Kim A.; Jablonka, Pascale; Hill, Vanessa; Starkenburg, Else; Lemasle, Bertrand; Shetrone, Matthew; Irwin, Mike; Norris, John; Yong, David; Gilmore, Gerry; Salvadori, Stephania; Skuladottir, Asa; Tolstoy, Eline; Bragaglia, A.; Arnaboldi, M.; Rejkuba, M.; Romano, D.

    2016-01-01

    Stars in low-mass dwarf galaxies show a larger range in their chemical properties than those in the Milky Way halo. The slower star formation efficiency make dwarf galaxies ideal systems for testing nucleosynthetic yields. Not only are alpha-poor stars found at lower metallicities, and a higher

  5. Chemical Speciation and Mobility of Some Heavy Metals in Soils ...

    African Journals Online (AJOL)

    The mobility of some heavy metals (Fe, Co, Ni and Mn) in soils around automobile waste dumpsites in Northern part of Niger Delta was assessed using Tessier et al. five syteps sequential chemical extraction procedure. The results showed that majority of iron and manganese were associated with the residual fraction with ...

  6. Physico-chemical parameters and heavy metal contents of Ibuya ...

    African Journals Online (AJOL)

    The physico-chemical parameters and heavy metal contents of Ibuya River were investigated between September 2012 and August 2013 from four stations using standard methods to etermine acceptable water quality standards and evaluate possible sustainability of a thriving fisheries cum tourist sport fishing venture.

  7. 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

  8. Design, Synthesis and Characterization of Functional Metal-Organic Framework Materials

    KAUST Repository

    Alamer, Badriah

    2015-06-01

    Over the past few decades, vast majority of industrial and academic research throughout the world has witnessed the emergence of materials that can serve as ideal candidates for potential utility in desired applications, and these materials are known as Metal Organic Framework (MOFs). This exceptional new family of porous materials is fabricated by linkage of metal ions or clusters and organic linkers via strong bonds. MOFs have been awarded with remarkable interest and widely studied due to their inherent structural methodology (e.g. use of various metals, expanded library of organic building blocks with different geometry and functionality particularly frameworks designed from carboxylate organic linkers) and unquestionably unique structural and chemical features for many practical applications. (i.e. gas storage/separation, catalysis, drug delivery etc). Simply, metal organic frameworks epitomize the beauty of porous chemical structures. From a design perspective, the introduction of the Molecular Building Block (MBB) approach is actively being pursued pathway by researchers toward the construction of MOFs by employing inorganic building blocks and organic linkers and taking advantage of not only their multiple coordination modes and geometries but also the way in which they are reticulated to generate final framework. In this thesis, research studies will be directed toward (i) the investigation of the relationship between experimental parameters and synthesis of well-known fcu –MOF, (ii) rational design and synthesis of new rare earth (RE) based MOFs, (ii) isoreticular materials based on particular MBB ([M3O(RCO2)6]), M= p-and d-block metals, and (iv) zeolite- like metal organic framework assembled from single-metal ion based MBB ([MN2(CO2)4]) via 2-, 3-,and 4-connected organic linkers. Consequently, the porosity, chemical and thermal stability, and gas sorption properties will be evaluated and detailed.

  9. Text Mining Metal-Organic Framework Papers.

    Science.gov (United States)

    Park, Sanghoon; Kim, Baekjun; Choi, Sihoon; Boyd, Peter G; Smit, Berend; Kim, Jihan

    2018-02-26

    We have developed a simple text mining algorithm that allows us to identify surface area and pore volumes of metal-organic frameworks (MOFs) using manuscript html files as inputs. The algorithm searches for common units (e.g., m 2 /g, cm 3 /g) associated with these two quantities to facilitate the search. From the sample set data of over 200 MOFs, the algorithm managed to identify 90% and 88.8% of the correct surface area and pore volume values. Further application to a test set of randomly chosen MOF html files yielded 73.2% and 85.1% accuracies for the two respective quantities. Most of the errors stem from unorthodox sentence structures that made it difficult to identify the correct data as well as bolded notations of MOFs (e.g., 1a) that made it difficult identify its real name. These types of tools will become useful when it comes to discovering structure-property relationships among MOFs as well as collecting a large set of data for references.

  10. Thin films by metal-organic precursor plasma spray

    International Nuclear Information System (INIS)

    Schulz, Douglas L.; Sailer, Robert A.; Payne, Scott; Leach, James; Molz, Ronald J.

    2009-01-01

    While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd) 3 ), triethylsilane (HSi(C 2 H 5 ) 3 or HSiEt 3 ), and titanium tetrakisdiethylamide (Ti(N(C 2 H 5 ) 2 ) 4 or Ti(NEt 2 ) 4 ) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt 3 showed the formation of SiC phase but Al(hd) 3 -derived films were amorphous. The Ti(NEt 2 ) 4 precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO 2 anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.

  11. Recent Advances as Materials of Functional Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Xiao-Lan Tong

    2013-01-01

    Full Text Available Metal-organic frameworks (MOFs, also known as hybrid inorganic-organic materials, represent an emerging class of materials that have attracted the imagination of solid-state chemists because MOFs combine unprecedented levels of porosity with a range of other functional properties that occur through the metal moiety and/or the organic ligand. The purpose of this critical review is to give a representative and comprehensive overview of the arising developments in the field of functional metal-organic frameworks, including luminescence, magnetism, and porosity through presenting examples. This review will be of interest to researchers and synthetic chemists attempting to design multifunctional MOFs.

  12. 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)

  13. Highly stable ni-m f6-nh2o/onpyrazine2(solvent)x metal organic frameworks and methods of use

    KAUST Repository

    Eddaoudi, Mohamed

    2016-10-13

    Provided herein are metal organic frameworks comprising metal nodes and N-donor organic ligands. Methods for capturing chemical species from fluid compositions comprise contacting a metal organic framework characterized by the formula [MaMbF6-n(O/H2O)w(Ligand)x(solvent)y]z with a fluid composition and capturing one or more chemical species from the fluid composition.

  14. Metal accumulation by stream bryophytes, related to chemical speciation

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, E. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)], E-mail: et@ceh.ac.uk; Vincent, C.D.; Lawlor, A.J.; Lofts, S. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)

    2008-12-15

    Metal accumulation by aquatic bryophytes was investigated using data for headwater streams of differing chemistry. The Windermere Humic Aqueous Model (WHAM) was applied to calculate chemical speciation, including competitive proton and metal interactions with external binding sites on the plants. The speciation modelling approach gives smaller deviations between observed and predicted bryophyte contents of Cu, Zn, Cd and Pb than regressions based on total filtered metal concentrations. If all four metals, and Ni, are considered together, the WHAM predictions are superior at the 1% level. Optimised constants for bryophyte binding by the trace metals are similar to those for humic substances and simple carboxylate ligands. Bryophyte contents of Na, Mg and Ca are approximately explained by binding at external sites, while most of the K is intracellular. Oxide phases account for some of the Al, and most of the Mn, Fe and Co. - Speciation modelling can be used to interpret the accumulation of Ni, Cu, Zn, Cd and Pb by bryophytes, supporting its use to quantify trace metal bioavailability in the field.

  15. Extraction of metal ions using chemically modified silica gel: a PIXE analysis.

    Science.gov (United States)

    Jal, P K; Dutta, R K; Sudarshan, M; Saha, A; Bhattacharyya, S N; Chintalapudi, S N; K Mishra, B

    2001-08-30

    Organic ligand with carboxyhydrazide functional group was immobilised on the surface of silica gel and the metal binding capacity of the ligand-embedded silica was investigated. The functional group was covalently bonded to the silica matrix through a spacer of methylene groups by sequential reactions of silica gel with dibromobutane, malonic ester and hydrazine in different media. Surface area value of the modified silica was determined. The changes in surface area were correlated with the structural change of the silica surface due to chemical modifications. A mixture solution of metal ions [K(I),Cr(III),Co(II),Ni(II),Cu(II),Zn(II),Hg(II) and U(VI)] was treated with the ligand-embedded silica in 10(-3) M aqueous solution. The measurement of metal extraction capacity of the silica based ligand was done by multielemental analysis of the metal complexes thus formed by using Proton Induced X-ray Emission (PIXE) technique.

  16. 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.

  17. From metal-organic squares to porous zeolite-like supramolecular assemblies

    KAUST Repository

    Wang, Shuang

    2010-12-29

    We report the synthesis, structure, and characterization of two novel porous zeolite-like supramolecular assemblies, ZSA-1 and ZSA-2, having zeolite gis and rho topologies, respectively. The two compounds were assembled from functional metal-organic squares (MOSs) via directional hydrogen-bonding interactions and exhibited permanent microporosity and thermal stability up to 300 °C. © 2010 American Chemical Society.

  18. Metal-organic framework catalysts for selective cleavage of aryl-ether bonds

    Science.gov (United States)

    Allendorf, Mark D.; Stavila, Vitalie

    2017-08-01

    The present invention relates to methods of employing a metal-organic framework (MOF) as a catalyst for cleaving chemical bonds. In particular instances, the MOF results in selective bond cleavage that results in hydrogenolyzis. Furthermore, the MOF catalyst can be reused in multiple cycles. Such MOF-based catalysts can be useful, e.g., to convert biomass components.

  19. Microporous metal-organic framework with potential for carbon dioxide capture at ambient conditions

    NARCIS (Netherlands)

    Xiang, S.C.; He, Y.; Zhang, Z.; Wu, H.; Zhou, W.; Krishna, R.; Chen, B.

    2012-01-01

    Carbon dioxide capture and separation are important industrial processes that allow the use of carbon dioxide for the production of a range of chemical products and materials, and to minimize the effects of carbon dioxide emission. Porous metal-organic frameworks are promising materials to achieve

  20. Effect of organic inputs on soil properties, heavy metal content and ...

    African Journals Online (AJOL)

    The quality of soil resources and productivity are important indices for agricultural enterprise. A randomized complete block design (RCBD) experiment was set up to evaluate the effects of organic wastes on the chemical properties, heavy metal content and root dry matter yield of spent engine oil (EO) contaminated soil in ...

  1. Metal-organic scintillator crystals for X-ray, gamma ray, and neutron detection

    Science.gov (United States)

    Boatner, Lynn A [Oak Ridge, TN; Kolopus, James A [Clinton, TN; Neal, John S [Knoxville, TN; Ramey, Joanne Oxendine [Knoxville, TN; Wisniewski, Dariusz J [Torun, PL

    2012-01-03

    New metal-organic materials are useful as scintillators and have the chemical formula LX.sub.3(CH.sub.3OH).sub.4 where L is Y, Sc, or a lanthanide element, and X is a halogen element. An example of the scintillator materials is CeCl.sub.3(CH.sub.3OH).sub.4.

  2. Lipase-supported metal-organic framework bioreactor catalyzes warfarin synthesis.

    Science.gov (United States)

    Liu, Wan-Ling; Yang, Ni-Shin; Chen, Ya-Ting; Lirio, Stephen; Wu, Cheng-You; Lin, Chia-Her; Huang, Hsi-Ya

    2015-01-02

    A green and sustainable strategy synthesizes clinical medicine warfarin anticoagulant by using lipase-supported metal-organic framework (MOF) bioreactors (see scheme). These findings may be beneficial for future studies in the industrial production of chemical, pharmaceutical, and agrochemical precursors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Electronic properties of metal-organic and organic-organic interfaces studied by photoemission and photoabsorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Molodtsova, Olga

    2006-07-01

    In this work systematic studies of the organic semiconductor CuPc have been presented. In general the investigation can be devided in three parts. In the first one we have studied the electronic structure of clean CuPc thin film. The next two parts are devoted to organic-organic and metal-organic interface formation, where one of the interface components is CuPc thin film. The main results of this thesis are: - The electronic structure of the pristine organic semiconductor CuPc has been obtained by a combination of conventional and resonant photoemission, near-edge X-ray absorption, as well as by theoretical ab initio quantum-chemical calculations. The contributions of different atomic species as well as sites of the CuPc molecule to the electronic DOS has been established. A combined experimental and theoretical study of the unoccupied electronic density of states of CuPc was presented. - The electronic properties of the organic heterointerfaces between fullerite and pristine copper phthalocyanine were studied. Both interfaces, CuPc/C{sub 60} and C{sub 60}/CuPc, were found to be non-reactive with pronounced shifts of the vacuum level pointing to the formation of an interfacial dipole mainly at the CuPc side of the heterojunctions. The dipole values are close to the difference of the work functions of the two materials. Important interface parameters and hole-injection barriers were obtained. The sequence of deposition does not influence the electronic properties of the interfaces. - CuPc doped with potassium was studied by means of photoemission and photoabsorption spectroscopy. A detailed analysis of the core-level PE spectra allows one to propose possible lattice sites, which harbor the potassium ions. The films prepared in this thesis showed no finite electronic density of states at the Fermi level. - Two stages of the In/CuPc interface formation have been distinguished. The low-coverage stage is characterized by a strong diffusion of the In atoms into the

  4. Global contamination trends of persistent organic chemicals

    National Research Council Canada - National Science Library

    Loganathan, Bommanna G; Lam, Paul K. S

    2012-01-01

    "Composed by a diverse group of experts, this reference covers the history, present status, and projected future trends of environmental contamination from highly toxic synthetic chemical pollutants...

  5. Solving crystal structures of metal and chemical hydrides

    OpenAIRE

    Cerny, Radovan

    2008-01-01

    The methods of structural characterization of metal and chemical hydrides are reviewed. The existing difficulties and problems are outlined and possible solutions presented. It is shown that powder diffraction, and especially the Direct Space Method, is essential component of hydride research. Crystal structures containing as many as 55 independent atoms (including hydrogen) have been fully characterized using powder diffraction. This is of great importance, because rapid collection of powder...

  6. Shock Wave Energy Dissipation by Metal-Organic Framework

    Science.gov (United States)

    Zhou, Xuan; Miao, Yurun; Banlusan, Kiettipong; Shaw, William; Strachan, Alejandro; Suslick, Kenneth; Dlott, Dana

    2017-06-01

    Metal-organic framework (MOF) such as ZIF-8 and UiO-66 show promising shock energy dissipation abilities through mechano-chemical reactions including bond breaking and pore collapse. In this work, we performed quantitative measurements on the shock wave energy attenuated by MOF films using a laser-driven flyer-plate apparatus. Aluminum flyer plates of 75-um thick were accelerated to speeds up to 2.0 km/s by a flat-top pulsed laser to impact the MOF film. The MOF layer was coated on a 200-nm thick gold mirror, which was deposited previously on glass substrate. Photonic Doppler velocimetry (PDV) was used to track the motions of the gold mirror, which can be converted to the energy flux and fluence of the shock wave that transmitted through the MOF layer. We deduced the shock energy that was attenuated by the MOF film by comparing the transmitted energy flux/fluence obtained with and without the presence of the MOF layer. A two-wave-shaped flux-time curve was obtained with the MOF layer because of its nanoporous structure. Studies on the shock wave energy attenuation by ZIF-8 and UiO-66 were carried out under various flyer speeds and sample thicknesses. We used in situ emission spectroscopy to verify that pore collapse was accompanied by chemical bond breakage. Corresponding author:dlott@illinois.edu.

  7. Metal-organic frameworks and their applications in catalysis; Redes metalorganicas e suas aplicacoes em catalise

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Andre Luis Dantas, E-mail: aldramos@ufs.br [Universidade Federal de Sergipe (UFSE), Sao Cristovao, SE (Brazil). Departamento de Engenharia Quimica; Tanase, Stefania; Rothenberg, Gadi [Van' t Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam (Netherlands)

    2014-07-01

    Metal-organic frameworks (MOFs) form a new class of materials with well-defined yet tunable properties. These are crystalline, highly porous and exhibit strong metal-ligand interactions. Importantly, their physical and chemical properties, including pore size, pore structure, acidity, and magnetic and optical characteristics, can be tailored by choosing the appropriate ligands and metal precursors. Here we review the key aspects of synthesis and characterization of MOFs, focusing on lanthanide-based and vanadium-based materials. We also outline some of their applications in catalysis and materials science. (author)

  8. Structural and chemical evolution of propionate based metal-organic precursors for superconducting YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} epitaxial film growth

    Energy Technology Data Exchange (ETDEWEB)

    Armenio, A Angrisani; Augieri, A; Galluzzi, V; Mancini, A; Rufoloni, A; Vannozzi, A; Celentano, G [Associazione EURATOM-ENEA sulla Fusione, Frascati Research Centre, Via E Fermi, 45, 00044 Frascati (Rome) (Italy); Ciontea, L; Petrisor, T [Technical University of Cluj-Napoca, Str. C. Daicoviciu 15, 3400 Cluj-Napoca (Romania); Contini, G; Giovannantonio, M Di [Istituto di Struttura della Materia-CNR, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Davoli, I, E-mail: giorgio.contini@ism.cnr.it, E-mail: giuseppe.celentano@enea.it [Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Rome (Italy)

    2011-11-15

    The structural and chemical evolution of propionate based low fluorine YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) precursor during the conversion thermal treatment to obtain superconducting film has been investigated by both x-ray photoelectron and diffraction techniques in a set of partially converted films on SrTiO{sub 3} single crystals. The pyrolysis temperature within the range 400-480 deg. C mainly affects the copper valence state with an increase of the Cu{sup 2+} fraction with temperature with respect to the Cu{sup 1+} oxidation state. During the subsequent thermal treatment up to 700 deg. C, the reduction of fluorine content is mainly ascribed to the hydrolysis of YF{sub 3}. At higher temperatures, Ba hydrolysis, Y{sub 2}Cu{sub 2}O{sub 5} and YBCO phase formation (nucleation at 700 deg. C and 725 deg. C, respectively) have been observed. The temperature dependences of the formation and decomposition of YBCO, Y{sub 2}Cu{sub 2}O{sub 5} and Ba-oxyfluoride were evaluated by x-ray diffraction measurements. The reaction path emerging from these analyses agrees with the one observed for YBCO films obtained with the standard MOD method based on metal tri-fluoroacetate precursors.

  9. Chemically engineered graphene-based 2D organic molecular magnet.

    Science.gov (United States)

    Hong, Jeongmin; Bekyarova, Elena; de Heer, Walt A; Haddon, Robert C; Khizroev, Sakhrat

    2013-11-26

    Carbon-based magnetic materials and structures of mesoscopic dimensions may offer unique opportunities for future nanomagnetoelectronic/spintronic devices. To achieve their potential, carbon nanosystems must have controllable magnetic properties. We demonstrate that nitrophenyl functionalized graphene can act as a room-temperature 2D magnet. We report a comprehensive study of low-temperature magnetotransport, vibrating sample magnetometry (VSM), and superconducting quantum interference (SQUID) measurements before and after radical functionalization. Following nitrophenyl (NP) functionalization, epitaxially grown graphene systems can become organic molecular magnets with ferromagnetic and antiferromagnetic ordering that persists at temperatures above 400 K. The field-dependent, surface magnetoelectric properties were studied using scanning probe microscopy (SPM) techniques. The results indicate that the NP-functionalization orientation and degree of coverage directly affect the magnetic properties of the graphene surface. In addition, graphene-based organic magnetic nanostructures were found to demonstrate a pronounced magneto-optical Kerr effect (MOKE). The results were consistent across different characterization techniques and indicate room-temperature magnetic ordering along preferred graphene orientations in the NP-functionalized samples. Chemically isolated graphene nanoribbons (CINs) were observed along the preferred functionality directions. These results pave the way for future magnetoelectronic/spintronic applications based on promising concepts such as current-induced magnetization switching, magnetoelectricity, half-metallicity, and quantum tunneling of magnetization.

  10. InAlN/InGaN/GaN double heterostructure with improved carrier confinement and high-temperature transport performance grown by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Zhao, Yi; Xue, Jun Shuai; Zhang, Jin Cheng; Zhou, Xiao Wei; Zhang, Ya Chao; Hao, Yue

    2015-01-01

    A nearly lattice-matched InAlN/InGaN/GaN double heterostructure (DH) and traditional InAlN/GaN single heterostructure (SH) were grown by metal–organic chemical vapor deposition. The InN mole fraction of InGaN channel was deduced by XRD and photoluminescence. The electrical properties were characterized by capacitance-voltage and temperature-dependent Hall measurements. Both results revealed that the InAlN/InGaN/GaN DH possessed superior carrier confinement over traditional InAlN/GaN SH owing to the back barrier formed at the InGaN/GaN interface, which prevents the spilling over of carriers and thus remarkably improves the transport performance at high temperature. Furthermore, a thin InGaN layer was preferable for carrier channel applications to a thick one. (paper)

  11. Metal organic framework MIL-101(Cr) for dehydration reactions

    Indian Academy of Sciences (India)

    aration, catalysis and drug delivery.1 MOFs possess unique two or three dimensional structures formed by the self-assembly of metal ions or metal clusters. (the connectors) are bridged with polytopic organic ligands as linkers, which allows the design of spe- cific nanometer-scale framework geometries with pore structures.

  12. Neutron powder diffraction of metal-organic frameworks for ...

    Indian Academy of Sciences (India)

    Abstract. We review recent structural studies that we have undertaken aimed at eluci- dating the fundamental properties of metal-organic framework materials and their inter- actions with hydrogen. We have shown that exposing coordinatively unsaturated metal centers can greatly enhance the hydrogen binding energy and ...

  13. Neutron powder diffraction of metal-organic frameworks for ...

    Indian Academy of Sciences (India)

    We review recent structural studies that we have undertaken aimed at elucidating the fundamental properties of metal-organic framework materials and their interactions with hydrogen. We have shown that exposing coordinatively unsaturated metal centers can greatly enhance the hydrogen binding energy and that they ...

  14. Molecular Speciation of Trace Metal Organic Complexes in the Pacific Ocean

    Science.gov (United States)

    Repeta, D.; Boiteau, R. M.; Bundy, R. M.; Babcock-Adams, L.

    2017-12-01

    Microbial production across approximately one third of the surface ocean is limited by extraordinarily low (picomolar) concentrations of dissolved iron, essentially all of which is complexed to strong organic ligands of unknown composition. Other biologically important trace metals (cobalt, copper, zinc, nickel) are also complexed to strong organic ligands, which again have not been extensively characterized. Nevertheless, organic ligands exert a strong influence on metal bioavailability and toxicity. For example, amendment experiments using commercially available siderophores, organic compounds synthesized by microbes to facilitate iron uptake, show these ligands can both facilitate or impede iron uptake depending on the siderophore composition and available uptake pathways. Over the past few years we have developed analytical techniques using high pressure liquid chromatography interfaced with inductively coupled plasma and electrospray ionization mass spectrometry to identify and quantify trace metal organic complexes in laboratory cultures of marine microbes and in seawater. We found siderophores to be widely distributed in the ocean, particularly in regions characterized by low iron concentrations. We also find chemically distinct complexes of copper, zinc, colbalt and nickel that we have yet to fully characterize. We will discuss some of our recent work on trace metal organic speciation in seawater and laboratory cultures, and outline future efforts to better understand the microbial cycling of trace metal organic complexes in the sea.

  15. Applications of metal-organic frameworks in heterogeneous supramolecular catalysis.

    Science.gov (United States)

    Liu, Jiewei; Chen, Lianfen; Cui, Hao; Zhang, Jianyong; Zhang, Li; Su, Cheng-Yong

    2014-08-21

    This review summarizes the use of metal-organic frameworks (MOFs) as a versatile supramolecular platform to develop heterogeneous catalysts for a variety of organic reactions, especially for liquid-phase reactions. Following a background introduction about catalytic relevance to various metal-organic materials, crystal engineering of MOFs, characterization and evaluation methods of MOF catalysis, we categorize catalytic MOFs based on the types of active sites, including coordinatively unsaturated metal sites (CUMs), metalloligands, functional organic sites (FOS), as well as metal nanoparticles (MNPs) embedded in the cavities. Throughout the review, we emphasize the incidental or deliberate formation of active sites, the stability, heterogeneity and shape/size selectivity for MOF catalysis. Finally, we briefly introduce their relevance into photo- and biomimetic catalysis, and compare MOFs with other typical porous solids such as zeolites and mesoporous silica with regard to their different attributes, and provide our view on future trends and developments in MOF-based catalysis.

  16. Novel Metal Organic Framework Synthesis for Spacecraft Oxygen Capture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek and University of Utah propose to develop novel metal organic framework (MOF) material to efficiently capture oxygen in spacecraft cabin environment. The...

  17. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids

    OpenAIRE

    Manjula I. Nandasiri; Jian Liu; B. Peter McGrail; Jeromy Jenks; Herbert T. Schaef; Vaithiyalingam Shutthanandan; Zimin Nie; Paul F. Martin; Satish K. Nune

    2016-01-01

    Metal-organic heat carriers (MOHCs) are recently developed nanofluids containing metal-organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with th...

  18. Fuel upgrading and reforming with metal organic framework

    KAUST Repository

    Eddaoudi, Mohamed

    2016-03-31

    Systems and methods for separating hydrocarbons on an internal combustion powered vehicle via one or more metal organic frameworks are disclosed. Systems and methods can further include utilizing separated hydrocarbons and exhaust to generate hydrogen gas for use as fuel. In one aspect, a method for separating hydrocarbons can include contacting a first component containing a first metal organic framework with a flow of hydrocarbons and separating hydrocarbons by size. In certain embodiments, the hydrocarbons can include alkanes.

  19. Metal organic frameworks for removal of compounds from a fluid

    KAUST Repository

    Eddaoudi, Mohamed

    2016-03-03

    Embodiments provide a method of compound removal from a fluid. The method includes contacting one or more metal organic framework (MOF) compositions with a fluid and sorbing one or more compounds, such as CO2, H2S and condensable hydrocarbons. One or more of CO2, H2S and condensable hydrocarbons can be sorbed simultaneously or in series. The metal organic framework can be an M-soc-MOF.

  20. Radioactivity in chemical and organic fertilizer used in Egypt

    International Nuclear Information System (INIS)

    Abbady, A.G.E.; Yousef, A.M.M.; Abbady, A.; El-Taher, A.

    2005-01-01

    The Egypt Chemical factories (ECF); such as Talkha, Sues, Abo Qeyer, Kafer Elzayat, and Assuit factories, produces and markets a range of phosphate based fertilizers, including Simple Super Phosphate (SSP) fertilizer, Triple Super Phosphate (TSP) fertilizer and Urea. Phosphate fertilizers produced by ECF are derived from phosphate ore. In addition to phosphate minerals, these ores can contain significant amounts of a wide range of impurities, including heavy metals and naturally occurring radionuclides. This study was carried out to determine the content of radionuclides in fertilizer products produced by ECF and some organic fertilizer (animal manure) includes cow, sheep and chicken fertilizer. In both samples (Chemical and organic fertilizers), the activity concentrations of Ra 2 26 are higher than those Th 2 32. The radioactivity of 226 R a in chemical fertilizers ranged from 21.6 ± 3.6 to 111.2 ± 8.9 Bq kg-1, phosphate fertilizers TSP contained high contents of 226 R a. The average radioactivity of 226 R a in TSP was 79.3 ± 7.4 Bq kg-1, in SSP 51.2 ± 5 Bq kg-1, and in Urea 35.1± 3.5 Bq kg-1. The activity of 232 T h in the different fertilizers ranged from 1.3 ± 1.1 to 9.9 ± 3.2 Bq kg-1,the highest activity observed in SSP fertilizer. The activity of 40 K was found to be great in the TSP fertilizer, which contained a mean activity 478.1± 21.3 Bq kg-1. With respect to organic fertilizers the average radioactivity of 226 R a, 232 T h and 40 K are 40 ± 1.6 Bq kg-1, 3.1± 1.2 and 427.1± 20 Bq kg-1. The data are discussed and compared with those given in the literatures. This study could be useful as baseline data for radiation exposure to fertilizers, and their impact on human health

  1. Physico-Chemical Properties of Kaolin-Organic Acid

    Directory of Open Access Journals (Sweden)

    Yeo S.W.

    2017-01-01

    Full Text Available Soil with more than 20% of organic content is classified as organic soil in Malaysia. Contents of organic soil consist of different types of organic and inorganic matter. Each type of organic matter has its own characteristic and its effect on the properties of the soil is different. Hence, a good understanding on the effect of specific organic and inorganic matter on the physico-chemical characteristic of organic soils can serve as a guide for predicting the properties of organic soils. The main objective is to unveil the effect of organic acid on the physico-chemical properties of soil. Artificial organic soil (kaolin mixed with organic acid was utilized in order to minimize the geochemical variability of studied soil. The organic acid which consists of humic acid and fulvic acid was extracted from highly humificated plant–based compost. The effect of organic acid on the physico-chemical properties of soil was determined by varying the concentration of organic acid. The specific gravity, Atterberg limits, pH, bulk chemical composition and the functional group of kaolin-organic acid were determined. It was found that the plasticity index, specific gravity and pH value were decreased with lowered concentration of organic acid. However, the liquid limits and plastic limits were found to be increased with the concentration decrement of organic acid. The analysis of XRF on the bulk chemical composition and analysis of FTIR spectra on the functional group of artificial organic soils with different concentration have confirmed little geochemical variability between samples.

  2. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING; FINAL

    International Nuclear Information System (INIS)

    LICHTENBERGER, DENNIS L.

    2002-01-01

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems

  3. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING

    Energy Technology Data Exchange (ETDEWEB)

    LICHTENBERGER, DENNIS L.

    2002-03-26

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems.

  4. Chemical vapor deposition of refractory metals and ceramics III

    International Nuclear Information System (INIS)

    Gallois, B.M.; Lee, W.Y.; Pickering, M.A.

    1995-01-01

    The papers contained in this volume were originally presented at Symposium K on Chemical Vapor Deposition of Refractory Metals and Ceramics III, held at the Fall Meeting of the Materials Research Society in Boston, Massachusetts, on November 28--30, 1994. This symposium was sponsored by Morton International Inc., Advanced Materials, and by The Department of Energy-Oak Ridge National Laboratory. The purpose of this symposium was to exchange scientific information on the chemical vapor deposition (CVD) of metallic and ceramic materials. CVD technology is receiving much interest in the scientific community, in particular, to synthesize new materials with tailored chemical composition and physical properties that offer multiple functionality. Multiphase or multilayered films, functionally graded materials (FGMs), ''smart'' material structures and nanocomposites are some examples of new classes of materials being produced via CVD. As rapid progress is being made in many interdisciplinary research areas, this symposium is intended to provide a forum for reporting new scientific results and addressing technological issues relevant to CVD materials and processes. Thirty four papers have been processed separately for inclusion on the data base

  5. Residual metallic contamination of transferred chemical vapor deposited graphene.

    Science.gov (United States)

    Lupina, Grzegorz; Kitzmann, Julia; Costina, Ioan; Lukosius, Mindaugas; Wenger, Christian; Wolff, Andre; Vaziri, Sam; Östling, Mikael; Pasternak, Iwona; Krajewska, Aleksandra; Strupinski, Wlodek; Kataria, Satender; Gahoi, Amit; Lemme, Max C; Ruhl, Guenther; Zoth, Guenther; Luxenhofer, Oliver; Mehr, Wolfgang

    2015-05-26

    Integration of graphene with Si microelectronics is very appealing by offering a potentially broad range of new functionalities. New materials to be integrated with the Si platform must conform to stringent purity standards. Here, we investigate graphene layers grown on copper foils by chemical vapor deposition and transferred to silicon wafers by wet etching and electrochemical delamination methods with respect to residual submonolayer metallic contaminations. Regardless of the transfer method and associated cleaning scheme, time-of-flight secondary ion mass spectrometry and total reflection X-ray fluorescence measurements indicate that the graphene sheets are contaminated with residual metals (copper, iron) with a concentration exceeding 10(13) atoms/cm(2). These metal impurities appear to be partially mobile upon thermal treatment, as shown by depth profiling and reduction of the minority charge carrier diffusion length in the silicon substrate. As residual metallic impurities can significantly alter electronic and electrochemical properties of graphene and can severely impede the process of integration with silicon microelectronics, these results reveal that further progress in synthesis, handling, and cleaning of graphene is required to advance electronic and optoelectronic applications.

  6. Reconfigurable electronics using conducting metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Talin, Albert Alec; Leonard, Francois; Stavila, Vitalie

    2017-07-18

    A device including a porous metal organic framework (MOF) disposed between two terminals, the device including a first state wherein the MOF is infiltrated by a guest species to form an electrical path between the terminals and a second state wherein the electrical conductivity of the MOF is less than the electrical conductivity in the first state. A method including switching a porous metal organic framework (MOF) between two terminals from a first state wherein a metal site in the MOF is infiltrated by a guest species that is capable of charge transfer to a second state wherein the MOF is less electrically conductive than in the first state.

  7. Chemical reactions in organic monomolecular layers. Condensation of hydrazine on carbonyl functions

    International Nuclear Information System (INIS)

    Rosilio, Charles; Ruaudel-Teixier, Annie.

    1976-01-01

    Evidence is given for chemical reactions of hydrazine (NH 2 -NH 2 ) with different carbonyl functional groups of organic molecules in the solid state, in monomolecular layer structures. The condensation of hydrazine with these molecules leads to conjugated systems by bridging the N-N links, to cyclizations, and also to polycondensations. The reactions investigated were followed up by infrared spectrophotometry, by transmission and metallic reflection. These chemical reactions revealed in the solid phase constitute a polycondensation procedure which is valuable in obtaining organized polymers in monomolecular layers [fr

  8. Chemical speciation of sulfur and metals in biogas reactors - Implications for cobalt and nickel bio-uptake processes.

    Science.gov (United States)

    Yekta, Sepehr Shakeri; Skyllberg, Ulf; Danielsson, Åsa; Björn, Annika; Svensson, Bo H

    2017-02-15

    This article deals with the interrelationship between overall chemical speciation of S, Fe, Co, and Ni in relation to metals bio-uptake processes in continuous stirred tank biogas reactors (CSTBR). To address this topic, laboratory CSTBRs digesting sulfur(S)-rich stillage, as well as full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed co-digestion, were targeted. Sulfur speciation was evaluated using acid volatile sulfide extraction and X-ray absorption spectroscopy. Metal speciation was evaluated by chemical fractionation, kinetic and thermodynamic analyses. Relative Fe to S content is identified as a critical factor for chemical speciation and bio-uptake of metals. In reactors treating sewage sludge, quantity of Fe exceeds that of S, inducing Fe-dominated conditions, while sulfide dominates in laboratory and co-digestion reactors due to an excess of S over Fe. Under sulfide-dominated conditions, metals availability for microorganisms is restricted due to formation of metal-sulfide precipitates. However, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by microorganisms under sulfidic conditions. Concentrations of free metal ions and labile metal complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This in turn enhances metal adsorption on cell surfaces and bio-uptake rates. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Electrocatalysis of chemically synthesized noble metal nanoparticles on carbon electrodes

    DEFF Research Database (Denmark)

    Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

    Noble metal nanoparticles (NPs), such as platinum (Pt) and palladium (Pd) NPs are promising catalysts for dioxygen reduction and oxidation of molecules such as formic acid and ethanol in fuel cells. Carbon nanomaterials are ideal supporting materials for electrochemical catalysts due to their good...... on their interfacial interaction with the supporting electrodes. In this work we aim at chemical production of size and shape controlled, specifically 22 nm cubic Pd NPs, and further understanding of the Pd NPs as electrocatalysts at the nanometer scale using both scanning tunneling microscopy (STM) and atomic force...

  10. Comparative studies of metals in fish organs, sediments and water from Nigerian fresh water fish ponds

    International Nuclear Information System (INIS)

    Ipinmoroti, K.O.; Oshodi, A.A.; Owolabi, R.A.

    1997-01-01

    Fish samples (Illisha africana) were collected from six man-made fish pond in Edo and Ondo states, Nigeria. Some organs of the fish sediment and water from the fish habitat were analysed for Cd, Pb, Hg, Ca, Fe, Zn, Cu and Cr, Physico-chemical properties of water samples from the ponds were also re-corded. The concentration of the metals varied in the sediment water as well as in different organs of the fish. However, chromium was absent in all the samples. The descending order of metal concentration in fish organs was: gills intestine, head and muscle. To avoid harmful accumulation of these metals in the human system, the gills and the intestine should preferably be discarded while processing fish for consumption. The head with a relatively high concentration of calcium might be useful in feed formulation. (author)

  11. Lewis acidic metal catalysed organic transformations by designed ...

    Indian Academy of Sciences (India)

    Administrator

    ing metal–organic frameworks containing Lewis acidic metal ions. The emphasis has been given to un- derstand the ... frameworks (MOFs) and metal–organic coordination networks (MOCNs) offer unique opportunities.5 .... of square-grid complex 1 was postulated to be more cationic than that of Cd(NO3)2⋅4H2O and thus.

  12. Functionalised metal-organic frameworks : A novel approach to stabilising single metal atoms

    NARCIS (Netherlands)

    Szilagyi, P.A.; Rogers, D. M.; Zaiser, I.; Callini, E; Turner, Stuart; Borgschulte, A; Züttel, A.; Geerlings, J.J.C.; Hirscher, M; Dam, B.

    2017-01-01

    We have investigated the potential of metal-organic frameworks for immobilising single atoms of transition metals using a model system of Pd supported on NH2-MIL-101(Cr). Our transmission electron microscopy and in situ Raman spectroscopy results give evidence for the first time that

  13. Antimicrobial efficacy of chemical disinfectants on contaminated full metal crowns.

    Science.gov (United States)

    Orsi, Iara Augusta; Villabona, Camilo Andrés; Kameoka, Eliana; Ferreira, Marly Christiènne C G; Ito, Izabel Yoko; Saravia, Marta Estela

    2010-01-01

    Prosthetic restorations that have been tried in the patient's mouth are potential sources of infection. In order to avoid cross-infection, protocols for infection control should be established in dental office and laboratory. This study evaluated the antimicrobial efficacy of disinfectants on full metal crowns contaminated with microorganisms. Full crowns cast in a Ni-Cr alloy were assigned to one control group (n=6) and 5 experimental groups (n=18). The crowns were placed in flat-bottom glass balloons and were autoclaved. A microbial suspension of each type of strain - S. aureus, P. aeruginosa, S. mutans, E. faecalis and C. albicans- was aseptically added to each experimental group, the crowns being allowed for contamination during 30 min. The contaminated specimens were placed into recipients with the chemical disinfectants (1% and 2% sodium hypochlorite and 2% glutaraldehyde) for 5, 10 and 15 min. Thereafter, the crowns were placed into tubes containing different broths and incubated at 35ºC. The control specimens were contaminated, immersed in distilled water for 20 min and cultured in Thioglycollate broth at 35ºC. Microbial growth assay was performed by qualitative visual examination after 48 h, 7 and 12 days. Microbial growth was noticed only in the control group. In the experimental groups, turbidity of the broths was not observed, regardless of the strains and immersion intervals, thus indicating absence of microbial growth. In conclusion, all chemical disinfectants were effective in preventing microbial growth onto full metal crowns.

  14. From bioavailability science to regulation of organic chemicals

    NARCIS (Netherlands)

    Ortega-Calvo, J.J.; Harmsen, J.; Parsons, J.R.; Semple, K.T.; Aitkin, M.D.; Ajao, C.; Eadsforth, C.; Galay-Burgos, M.; Naidu, R.; Oliver, R.; Peijnenburg, W.J.G.M.; Römbke, J.; Streck, G.; Versonnen, B.

    2015-01-01

    The bioavailability of organic chemicals in soil and sediment is an important area of scientific investigation for environmental scientists, although this area of study remains only partially recognized by regulators and industries working in the environmental sector. Regulators have recently

  15. Metal Complexes for Organic Optoelectronic Applications

    Science.gov (United States)

    Huang, Liang

    Organic optoelectronic devices have drawn extensive attention by over the past two decades. Two major applications for Organic optoelectronic devices are efficient organic photovoltaic devices(OPV) and organic light emitting diodes (OLED). Organic Solar cell has been proven to be compatible with the low cost, large area bulk processing technology and processed high absorption efficiencies compared to inorganic solar cells. Organic light emitting diodes are a promising approach for display and solid state lighting applications. To improve the efficiency, stability, and materials variety for organic optoelectronic devices, several emissive materials, absorber-type materials, and charge transporting materials were developed and employed in various device settings. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. In this thesis, Chapter 1 provides an introduction to the background knowledge of OPV and OLED research fields presented. Chapter 2 discusses new porphyrin derivatives- azatetrabenzylporphyrins for OPV and near infrared OLED applications. A modified synthetic method is utilized to increase the reaction yield of the azatetrabenzylporphyrin materials and their photophysical properties, electrochemical properties are studied. OPV devices are also fabricated using Zinc azatetrabenzylporphyrin as donor materials. Pt(II) azatetrabenzylporphyrin were also synthesized and used in near infra-red OLED to achieve an emission over 800 nm with reasonable external quantum efficiencies. Chapter 3, discusses the synthesis, characterization, and device evaluation of a series of tetradentate platinum and palladium complexesfor single doped white OLED applications and RGB white OLED applications. Devices employing some of the developed emitters demonstrated impressively high external quantum efficiencies within the range of 22%-27% for various emitter concentrations. And the palladium complex, i

  16. Baade's window and APOGEE. Metallicities, ages, and chemical abundances

    Science.gov (United States)

    Schultheis, M.; Rojas-Arriagada, A.; García Pérez, A. E.; Jönsson, H.; Hayden, M.; Nandakumar, G.; Cunha, K.; Allende Prieto, C.; Holtzman, J. A.; Beers, T. C.; Bizyaev, D.; Brinkmann, J.; Carrera, R.; Cohen, R. E.; Geisler, D.; Hearty, F. R.; Fernandez-Tricado, J. G.; Maraston, C.; Minnitti, D.; Nitschelm, C.; Roman-Lopes, A.; Schneider, D. P.; Tang, B.; Villanova, S.; Zasowski, G.; Majewski, S. R.

    2017-04-01

    Context. Baade's window (BW) is one of the most observed Galactic bulge fields in terms of chemical abundances. Owing to its low and homogeneous interstellar absorption it is considered the perfect calibration field for Galactic bulge studies. Aims: In the era of large spectroscopic surveys, calibration fields such as BW are necessary for cross calibrating the stellar parameters and individual abundances of the APOGEE survey. Methods: We use the APOGEE BW stars to derive the metallicity distribution function (MDF) and individual abundances for α- and iron-peak elements of the APOGEE ASPCAP pipeline (DR13), as well as the age distribution for stars in BW. Results: We determine the MDF of APOGEE stars in BW and find a remarkable agreement with that of the Gaia-ESO survey (GES). Both exhibit a clear bimodal distribution. We also find that the Mg-metallicity planes of the two surveys agree well, except for the metal-rich part ([Fe/H] > 0.1), where APOGEE finds systematically higher Mg abundances with respect to the GES. The ages based on the [C/N] ratio reveal a bimodal age distribution, with a major old population at 10 Gyr, with a decreasing tail towards younger stars. A comparison of stellar parameters determined by APOGEE and those determined by other sources reveals detectable systematic offsets, in particular for spectroscopic surface gravity estimates. In general, we find a good agreement between individual abundances of O, Na, Mg, Al, Si, K, Ca, Cr, Mn, Co, and Ni from APOGEE with that of literature values. Conclusions: We have shown that in general APOGEE data show a good agreement in terms of MDF and individual chemical abundances with respect to literature works. Using the [C/N] ratio we found a significant fraction of young stars in BW.

  17. 2-periodic metal-organic frameworks (MOFs) as supermolecular building layers (SBLs) for making targeted 3-periodic MOFs

    KAUST Repository

    Eddaoudi, Mohamed

    2015-09-22

    Embodiments of the present disclosure provide for chemical assemblies, multidimensional metal-organic frameworks (MOFs), supermolecular building layers (SBLs), inorganic molecular building blocks (MBBs), organic MBBs (designed ligands), methods of making each, and methods of using each, and the like. In an embodiment, the composition can be used in catalysis, separations, gas storage, and drug delivery.

  18. Trace metals in pelagic organisms from the Mediterranean Sea

    International Nuclear Information System (INIS)

    Fowler, S.W.; Oregioni, B.; LaRosa, J.

    1976-01-01

    As a result of current interest in heavy metal pollution in the marine environment much information is accruing on the present levels of metals in certain marine species. By far the majority of the studies have involved elemental analysis of coastal organisms which are relatively easy to collect. However, due to inherent problems in sampling, far less information exists on element concentration in pelagic organisms, species which are important in terms of total marine biomass, their position in the food web, and their ability to concentrate and transport relatively large amounts of metals in various ways. Microplankton and larger zooplanktonic and nektonic species were sampled over a wide geographical range throughout the Mediterranean as well as along selected transects to assess possible gradients in metal concentrations in plankton communities

  19. Gravimetric chemical sensors based on silica-based mesoporous organic-inorganic hybrids.

    Science.gov (United States)

    Xu, Jiaqiang; Zheng, Qi; Zhu, Yongheng; Lou, Huihui; Xiang, Qun; Cheng, Zhixuan

    2014-09-01

    Silica-based mesoporous organic-inorganic hybrid material modified quartz crystal microbalance (QCM) sensors have been examined for their ability to achieve highly sensitive and selective detection. Mesoporous silica SBA-15 serves as an inorganic host with large specific surface area, facilitating gas adsorption, and thus leads to highly sensitive response; while the presence of organic functional groups contributes to the greatly improved specific sensing property. In this work, we summarize our efforts in the rational design and synthesis of novel sensing materials for the detection of hazardous substances, including simulant nerve agent, organic vapor, and heavy metal ion, and develop high-performance QCM-based chemical sensors.

  20. Metal-Organic Frameworks Stabilize Solution-Inaccessible Cobalt Catalysts for Highly Efficient Broad-Scope Organic Transformations.

    Science.gov (United States)

    Zhang, Teng; Manna, Kuntal; Lin, Wenbin

    2016-03-09

    New and active earth-abundant metal catalysts are critically needed to replace precious metal-based catalysts for sustainable production of commodity and fine chemicals. We report here the design of highly robust, active, and reusable cobalt-bipyridine- and cobalt-phenanthroline-based metal-organic framework (MOF) catalysts for alkene hydrogenation and hydroboration, aldehyde/ketone hydroboration, and arene C-H borylation. In alkene hydrogenation, the MOF catalysts tolerated a variety of functional groups and displayed unprecedentedly high turnover numbers of ∼2.5 × 10(6) and turnover frequencies of ∼1.1 × 10(5) h(-1). Structural, computational, and spectroscopic studies show that site isolation of the highly reactive (bpy)Co(THF)2 species in the MOFs prevents intermolecular deactivation and stabilizes solution-inaccessible catalysts for broad-scope organic transformations. Computational, spectroscopic, and kinetic evidence further support a hitherto unknown (bpy(•-))Co(I)(THF)2 ground state that coordinates to alkene and dihydrogen and then undergoing σ-complex-assisted metathesis to form (bpy)Co(alkyl)(H). Reductive elimination of alkane followed by alkene binding completes the catalytic cycle. MOFs thus provide a novel platform for discovering new base-metal molecular catalysts and exhibit enormous potential in sustainable chemical catalysis.

  1. A Kind of Energy Storage Technology: Metal Organic Frameworks

    OpenAIRE

    Ozturk, Zeynel; Kose, D. A.; Asan, A.; Ozturk, B.

    2016-01-01

    For last fifteen years energy has been transferred by using electricity and as an energy carrier media electricity has some disadvantages like its wire need for transportation and its being non-storable for large amounts. To store more energy safely and for transportation it easily, new storing medias and devices are needed. For easy and safe energy transport there are many technologies and some of these contain hydrogen energy. Metal hydrides, carbon nanotubes, metal organic frameworks (MOFs...

  2. Alkylamine functionalized metal-organic frameworks for composite gas separations

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R.; McDonald, Thomas M.; D' Alessandro, Deanna M.

    2018-01-09

    Functionalized metal-organic framework adsorbents with ligands containing basic nitrogen groups such as alkylamines and alkyldiamines appended to the metal centers and method of isolating carbon dioxide from a stream of combined gases and carbon dioxide partial pressures below approximately 1 and 1000 mbar. The adsorption material has an isosteric heat of carbon dioxide adsorption of greater than -60 kJ/mol at zero coverage using a dual-site Langmuir model.

  3. Cytotoxicity of nanoscaled metal-organic frameworks

    OpenAIRE

    Tamames-Tabar, Cristina; Cunha, Denise; Imbuluzqueta, Edurne; Ragon, Florence; Serre, Christian; Blanco-Prieto, Maria J.; Horcajada, Patricia

    2014-01-01

    A series of fourteen porous Metal–Organic Frameworks (MOFs) with different compositions (Fe, Zn, and Zr; carboxylates or imidazolates) and structures have been successfully synthesised at the nanoscale and fully characterised by XRPD, FTIR, TGA, N2 porosimetry, TEM, DLS and z-potential. Their toxicological assessment was performed using two different cell lines: human epithelial cells from foetal cervical carcinoma (HeLa) and murine macrophage cell line (J774). It appears that MOF...

  4. Bioavailability of heavy metals in soil: impact on microbial biodegradation of organic compounds and possible improvement strategies.

    Science.gov (United States)

    Olaniran, Ademola O; Balgobind, Adhika; Pillay, Balakrishna

    2013-05-15

    Co-contamination of the environment with toxic chlorinated organic and heavy metal pollutants is one of the major problems facing industrialized nations today. Heavy metals may inhibit biodegradation of chlorinated organics by interacting with enzymes directly involved in biodegradation or those involved in general metabolism. Predictions of metal toxicity effects on organic pollutant biodegradation in co-contaminated soil and water environments is difficult since heavy metals may be present in a variety of chemical and physical forms. Recent advances in bioremediation of co-contaminated environments have focussed on the use of metal-resistant bacteria (cell and gene bioaugmentation), treatment amendments, clay minerals and chelating agents to reduce bioavailable heavy metal concentrations. Phytoremediation has also shown promise as an emerging alternative clean-up technology for co-contaminated environments. However, despite various investigations, in both aerobic and anaerobic systems, demonstrating that metal toxicity hampers the biodegradation of the organic component, a paucity of information exists in this area of research. Therefore, in this review, we discuss the problems associated with the degradation of chlorinated organics in co-contaminated environments, owing to metal toxicity and shed light on possible improvement strategies for effective bioremediation of sites co-contaminated with chlorinated organic compounds and heavy metals.

  5. Bioavailability of Heavy Metals in Soil: Impact on Microbial Biodegradation of Organic Compounds and Possible Improvement Strategies

    Directory of Open Access Journals (Sweden)

    Balakrishna Pillay

    2013-05-01

    Full Text Available Co-contamination of the environment with toxic chlorinated organic and heavy metal pollutants is one of the major problems facing industrialized nations today. Heavy metals may inhibit biodegradation of chlorinated organics by interacting with enzymes directly involved in biodegradation or those involved in general metabolism. Predictions of metal toxicity effects on organic pollutant biodegradation in co-contaminated soil and water environments is difficult since heavy metals may be present in a variety of chemical and physical forms. Recent advances in bioremediation of co-contaminated environments have focussed on the use of metal-resistant bacteria (cell and gene bioaugmentation, treatment amendments, clay minerals and chelating agents to reduce bioavailable heavy metal concentrations. Phytoremediation has also shown promise as an emerging alternative clean-up technology for co-contaminated environments. However, despite various investigations, in both aerobic and anaerobic systems, demonstrating that metal toxicity hampers the biodegradation of the organic component, a paucity of information exists in this area of research. Therefore, in this review, we discuss the problems associated with the degradation of chlorinated organics in co-contaminated environments, owing to metal toxicity and shed light on possible improvement strategies for effective bioremediation of sites co-contaminated with chlorinated organic compounds and heavy metals.

  6. Bioavailability of Heavy Metals in Soil: Impact on Microbial Biodegradation of Organic Compounds and Possible Improvement Strategies

    Science.gov (United States)

    Olaniran, Ademola O.; Balgobind, Adhika; Pillay, Balakrishna

    2013-01-01

    Co-contamination of the environment with toxic chlorinated organic and heavy metal pollutants is one of the major problems facing industrialized nations today. Heavy metals may inhibit biodegradation of chlorinated organics by interacting with enzymes directly involved in biodegradation or those involved in general metabolism. Predictions of metal toxicity effects on organic pollutant biodegradation in co-contaminated soil and water environments is difficult since heavy metals may be present in a variety of chemical and physical forms. Recent advances in bioremediation of co-contaminated environments have focussed on the use of metal-resistant bacteria (cell and gene bioaugmentation), treatment amendments, clay minerals and chelating agents to reduce bioavailable heavy metal concentrations. Phytoremediation has also shown promise as an emerging alternative clean-up technology for co-contaminated environments. However, despite various investigations, in both aerobic and anaerobic systems, demonstrating that metal toxicity hampers the biodegradation of the organic component, a paucity of information exists in this area of research. Therefore, in this review, we discuss the problems associated with the degradation of chlorinated organics in co-contaminated environments, owing to metal toxicity and shed light on possible improvement strategies for effective bioremediation of sites co-contaminated with chlorinated organic compounds and heavy metals. PMID:23676353

  7. Assessment of heavy metal removal technologies for biowaste by physico-chemical fractionation

    NARCIS (Netherlands)

    Veeken, A.H.M.; Hamelers, H.V.M.

    2003-01-01

    In the Netherlands, the heavy metal content of biowaste-compost frequently exceeds the legal standards for heavy metals. In order to assess heavy metal removal technologies, a physico-chemical fractionation scheme was developed to gain insight into the distribution of heavy metals (Cd, Cu, Pb and

  8. Mechanochemical synthesis and characterisation of cocrystals and metal organic compounds.

    Science.gov (United States)

    Tröbs, L; Emmerling, F

    2014-01-01

    The mechanochemical synthesis of two model compounds, a metal organic framework (H2Im)[Bi(1,4-bdc)2] (bdc = benzene dicarboxylate, H2Im = imidazole cation)) and a cocrystal (carbamazepine : indometacin 1 : 1) were followed ex situ using a combination of two analytical methods. Powder X-ray diffraction (XRD) and Raman spectroscopy data were evaluated for the synthesis of the metal organic framework. The XRD measurements and REM images were analysed for the synthesis of the cocrystal. The measurements revealed that both model compounds were synthesised within minutes. The metal organic framework (H2Im)[Bi(1,4-bdc)2] is synthesised via an intermediate structure. The cocrystal carbamazepine : indometacin 1 : 1 is formed within a few seconds. The crystallite size decreases during the further milling treatment.

  9. Inorganic Metal Oxide/Organic Polymer Nanocomposites And Method Thereof

    Science.gov (United States)

    Gash, Alexander E.; Satcher, Joe H.; Simpson, Randy

    2004-11-16

    A synthetic method for preparation of hybrid inorganic/organic energetic nanocomposites is disclosed herein. The method employs the use of stable metal in organic salts and organic solvents as well as an organic polymer with good solubility in the solvent system to produce novel nanocomposite energetic materials. In addition, fuel metal powders (particularly those that are oxophilic) can be incorporated into composition. This material has been characterized by thermal methods, energy-filtered transmission electron microscopy (EFTEM), N.sub.2 adsoprtion/desorption methods, and Fourier-Transform (FT-IR) spectroscopy. According to these characterization methods the organic polymer phase fills the nanopores of the material, providing superb mixing of the component phases in the energetic nanocomposite.

  10. Microporous metal-organic framework with potential for carbon dioxide capture at ambient conditions.

    Science.gov (United States)

    Xiang, Shengchang; He, Yabing; Zhang, Zhangjing; Wu, Hui; Zhou, Wei; Krishna, Rajamani; Chen, Banglin

    2012-07-17

    Carbon dioxide capture and separation are important industrial processes that allow the use of carbon dioxide for the production of a range of chemical products and materials, and to minimize the effects of carbon dioxide emission. Porous metal-organic frameworks are promising materials to achieve such separations and to replace current technologies, which use aqueous solvents to chemically absorb carbon dioxide. Here we show that a metal-organic frameworks (UTSA-16) displays high uptake (160 cm(3) cm(-3)) of CO(2) at ambient conditions, making it a potentially useful adsorbent material for post-combustion carbon dioxide capture and biogas stream purification. This has been further confirmed by simulated breakthrough experiments. The high storage capacities and selectivities of UTSA-16 for carbon dioxide capture are attributed to the optimal pore cages and the strong binding sites to carbon dioxide, which have been demonstrated by neutron diffraction studies.

  11. CHEMICAL TRANSPORT FACILITATED BY COLLOIDAL-SIZED ORGANIC MOLECULES

    Science.gov (United States)

    The fluid passing through the pores of soils and geologic materials is not just water with dissolved inorganic chemicals, but a complex mixture of organic and inorganic molecules. Large organic molecules such as humic and fulvic materials may impact the movement of contaminants. ...

  12. Chemical and sequential analysis of some metals in sediments from the North Coast of the Gulf of Mexico

    International Nuclear Information System (INIS)

    Trinidad Martinez; Brenda Estanol; Miguel Angel Zuniga

    2016-01-01

    Sediments collected from the North Coast of the Gulf of Mexico got carefully mixed, dried, and finally subjected to physical and chemical analysis. Metal concentration was determined by energy dispersive X-ray fluorescence (EDXRF). Sequential chemical analysis was performed by modified TESSIER technique. Results and statistical analysis (α = 0.05) show concentrations of most elements (excepting Mn, Ca, Ga, As and Pb) in the range of those of the earth crust's values, which set a sampling zone base line. Sequential extraction shows the potential risk of mobilization of metals sequestered in particulate phases by oxidation of anoxic sediments or intense organic matter degradation. (author)

  13. Membrane-Organized Chemical Photoredox Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, James K.

    2014-09-18

    This project has three interrelated goals relevant to solar water photolysis, which are to develop: (1) vesicle-organized assemblies for H2 photoproduction that utilize pyrylium and structurally related compounds as combined photosensitizers and cyclic electroneutral transmembrane electron carriers; (2) transmembrane redox systems whose reaction rates can be modulated by light; and (3) homogeneous catalysts for water oxidation. . In area (1), initial efforts to photogenerate H2 from vectorially-organized vesicles containing occluded colloidal Pt and commonly available pyrylium ions as transmembrane redox mediators were unsuccessful. New pyrylium compounds with significantly lower reduction potentials have been synthesized to address this problem, their apparent redox potentials in functioning systems have been now evaluated by using a series of occluded viologens, and H2 photoproduction has been demonstrated in continuous illumination experiments. In area (2), spirooxazine-quinone dyads have been synthesized and their capacity to function as redox mediators across bilayer membranes has been evaluated through continuous photolysis and transient spectrophotometric measurements. Photoisomerization of the spiro moiety to the ring-open mero form caused net quantum yields to decrease significantly, providing a basis for photoregulation of transmembrane redox. Research on water oxidation (area 3) has been directed at understanding mechanisms of catalysis by cis,cis-[(bpy)2Ru(OH2)]2O4+ and related polyimine complexes. Using a variety of physical techniques, we have: (i) identified the redox state of the complex ion that is catalytically active; (ii) shown using 18O isotopic labeling that there are two reaction pathways, both of which involve participation of solvent H2O; and (iii) detected and characterized by EPR and resonance Raman spectroscopies new species which may be key intermediates in the catalytic cycle.

  14. Removal of trace organic chemical contaminants by a membrane bioreactor.

    Science.gov (United States)

    Trinh, T; van den Akker, B; Stuetz, R M; Coleman, H M; Le-Clech, P; Khan, S J

    2012-01-01

    Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.

  15. Metal organic frameworks as a drug delivery system for flurbiprofen

    Directory of Open Access Journals (Sweden)

    AL Haydar M

    2017-09-01

    Full Text Available Muder AL Haydar,1,2 Hussein Rasool Abid,3,4 Bruce Sunderland,2 Shaobin Wang5,6 1Pharmaceutics Department, College of the Pharmacy, University of Kerbala, Kerbala, Iraq; 2Pharmaceutics Department, School of Pharmacy, Faculty of Health Sciences, Curtin University, Perth, WA, Australia; 3Department of Chemical Engineering, Curtin University, Perth, WA, Australia; 4College of Applied Medical Sciences, University of Kerbala, Kerbala, Iraq; 5School of Pharmacy, Faculty of Health Sciences, Curtin University, Perth, WA, Australia; 6Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Faculty of Science and Engineering, Curtin University, Perth, WA, Australia Background: Metal organic frameworks (MOFs have attracted more attention in the last decade because of a suitable pore size, large surface area, and high pore volume. Developing biocompatible MOFs such as the MIL family as a drug delivery system is possible. Purpose: Flurbiprofen (FBP, a nonsteroidal anti-inflammatory agent, is practically insoluble in aqueous solution, and, therefore, needs suitable drug delivery systems. Different biocompatible MOFs such as Ca-MOF and Fe-MILs (53, 100, and 101 were synthesized and employed for FBP delivery. Patients and methods: A sample of 50 mg of each MOF was mixed and stirred for 24 h with 10 mL of 5 mg FBP in acetonitrile (40% in a sealed container. The supernatant of the mixture after centrifuging was analyzed by high-performance liquid chromatography to determine the loaded quantity of FBP on the MOF. The overnight-dried solid material after centrifuging the mixture was analyzed for loading percent using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, nuclear magnetic resonance, and FBP release profile. Results: The loading values of FBP were achieved at 10.0%±1%, 20%±0.8%, 37%±2.3%, and 46%±3.1% on Ca-MOF, Fe-MIL-53, Fe-MIL-101, and Fe-MIL-100, respectively. The FBP release

  16. The Precious metals (Au, Ag, Pt, Pd, Rh) adsorption on the Silicon – organic sorbents

    OpenAIRE

    G Burmaa; S Alen; Yu Ganchimeg; I Sukhbaatar

    2014-01-01

    Sorption activity of two types of Silicon-organic sorbents for the previous metals has been studied. A polymer – poly (3- silsesquioxanilpropylthiocarbamate) - 3- silsesquioxanilpropylammonium which was obtained by the hydrolytic poly-condensation reaction and has been determined its physical, chemical characteristics and its sorption activity for the Ag(I), Au(III), Pt(IV), Pd(II), Rh(III). It has been found out that the sorbent shows high static sorption of Gold (III), Mercury (II) at acidi...

  17. Humic acid metal cation interaction studied by spectromicroscopy techniques in combination with quantum chemical calculations.

    Science.gov (United States)

    Plaschke, M; Rothe, J; Armbruster, M K; Denecke, M A; Naber, A; Geckeis, H

    2010-03-01

    Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the (5)D(0) --> (7)F(1,2) fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a ;pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.

  18. CMP [Chemicals, Metals, and Pesticides] Pits: Environmental information document

    International Nuclear Information System (INIS)

    Scott, S.C.; Kolb, N.L.; Price, V.; Bledsoe, H.W.

    1986-12-01

    This document provides environmental information on postulated closure options for the Chemicals, Metals, and Pesticides (CMP) Pits at the Savannah River Plant and was developed as background technical documentation for the Department of Energy's proposed Environmental Impact Statement (EIS) on waste management activities for groundwater protection at the plant. The results of groundwater and atmospheric pathway analyses, accident analysis, and other environmental assessments discussed in this document are based upon a conservative analysis of all foreseeable scenarios as defined by the National Environmental Policy Act (40 CFR 1500-1508). The scenarios do not necessarily represent actual environmental conditions. This document is not meant to be used as a regulatory closure plan or other regulatory document to comply with required federal or state environmental regulations

  19. EXAFS characterization of supported metal catalysts in chemically dynamic environments

    International Nuclear Information System (INIS)

    Robota, H.J.

    1991-01-01

    Characterization of catalysts focuses on the identification of an active site responsible for accelerating desirable chemical reactions. The identification, characterization, and selective modification of such sites is fundamental to the development of structure-function relationships. Unfortunately, this goal is far from realized in nearly all catalysts, and particularly in catalysts comprised of small supported metal particles. X-ray absorption spectroscopy (XAS) has had a dramatic effect on our understanding of supported metal particles in their resting state. However, the performance of a catalyst can not be assessed from such simple resting state measurements. Among the factors which influence catalyst performance are the exact catalyst composition, including the support and any modifiers; particle size; catalyst finishing and pretreatment conditions; pressure, composition, and temperature of the operating environment; time. Gaining an understanding of how the structure of a catalytic site can change with such an array of variables requires that we begin to develop measurement methods which are effective under chemically dynamic conditions. Ideally, it should be possible to obtain a full X-ray absorption spectrum of each element thought to have a causal relationship with observed catalyst properties. From these spectra, we can optimally extract only a relatively limited amount of information which we must then piece together with information derived from other characterization methods and intuition to arrive at a hypothetical structure of the operating catalyst. Information about crystallinity, homogeneity, and general disorder can be obtained from the Debye-Waller factor. Finally, through analogy with known compounds, the electronic structure of the active atoms can be inferred from near edge absorption features

  20. Comparative toxicity of ten organic chemicals to four earthworm species

    Energy Technology Data Exchange (ETDEWEB)

    Neuhauser, E.F.; Durkin, P.R.; Malecki, M.R.; Anatra, M.

    1986-01-01

    Ten organic chemicals were tested for toxicity to four earthworm species: Allolobophora tuberculata, Eisenia fetida, Eudrilus eugeniae and Perionyx excavatus, using the European Economic Community's (EEC) earthworm artificial soil and contact testing procedure. The phenols were the most toxic chemicals tested, followed by the amine, substituted benzenes, halogenated aliphatic hydrocarbon, polycyclic aromatic hydrocarbon and phthalate as the least toxic chemical tested. Correlations among species within each type of test for a given chemical were extremely high, suggesting that the selection of earthworm test species does not markedly affect the assessment of a chemical's toxicity. The correlation between the two tests was low for all test species. The contact test LC50 for a given chemical cannot be directly correlated to an artificial soil test LC50 for the same earthworm species.

  1. Destruction of Moulding Sands with Chemical Binders Caused by the Thermal Radiation of Liquid Metal

    Directory of Open Access Journals (Sweden)

    Zych J.

    2015-12-01

    Full Text Available The obtained results of heating of sand moulds with binders by means of a thermal radiation of liquid metal are presented in this study. Standard samples for measuring Rg made of the tested moulding sands were suspended at the lower part of the cover which was covering the crucible with liquid metal (cast iron, placed in the induction furnace. The authors own methodology was applied in investigations. The progressing of the samples surface layers heating process was determined as the heating time function. Samples of a few kinds of moulding sands with chemical binders were tested. Samples without protective coatings as well as samples with such coatings were tested. The influence of the thermal radiation on bending resistance of samples after their cooling was estimated. The influence of several parameters such as: time of heating, distance from the metal surface, metal temperature, application of coatings, were tested. A very fast loss of strength of moulding sands with organic binders was found, especially in cases when the distance between metal and sample surfaces was small and equaled to 10÷15 mm. Then, already after app. 15 seconds of the radiation (at Tmet=1400°C, the resistance decreases by nearly 70%. Generally, moulding sands with organic binders are losing their strength very fast, while moulding sands with water glass at first increase their strength and later slightly lose. The deposition of protective coatings increases the strength of the mould surface layers, however does not allow to retain this strength after the metal thermal radiation.

  2. Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures.

    Science.gov (United States)

    Piacenza, Elena; Presentato, Alessandro; Turner, Raymond J

    2018-02-25

    In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids, DNA, and polysaccharides) or secondary metabolites (e.g. flavonoids, terpenoids, glycosides, organic acids, and alkaloids) naturally produced by organisms have been indicated as main contributors to the stabilization of Bio-Me-nanostructures. Nevertheless, the chemical-physical mechanisms behind the ability of these molecules in providing stability to Bio-Me-nanomaterials are unknown. In this context, transposing the stabilization theory of chemically synthesized Me-nanomaterials (Ch-Me-nanomaterials) to biogenic materials can be used towards a better comprehension of macromolecules and secondary metabolites role as stabilizing agents of Bio-Me-nanomaterials. According to this theory, nanomaterials are generally featured by high thermodynamic instability in suspension, due to their high surface area and surface energy. This feature leads to the necessity to stabilize chemical nanostructures, even during or directly after their synthesis, through the development of (i) electrostatic, (ii) steric, or (iii) electrosteric interactions occurring between molecules and nanomaterials in suspension. Based on these three mechanisms, this review is focused on parallels between the stabilization of biogenic or chemical nanomaterials, suggesting which chemical-physical mechanisms may be

  3. Speciation and Distribution of Trace Metals and Organic Matter in Marine Lake as In Situ Laboratory

    Science.gov (United States)

    Mlakar, M.; Fiket, Ž.; Cuculić, V.; Cukrov, N.; Geček, S.

    2016-02-01

    Marine lakes are unique, isolated marine systems, also recognized as in situ "laboratories" in which geochemical processes on a different scale compared to the open sea, can be observed. Impact of organic matter cycling on distribution of trace metals in the marine lake Mir, located on Dugi Otok Island, in the central part of the eastern Adriatic Sea, was investigated. Intense spatial and seasonal variations of physico-chemical parameters and organic matter concentrations in the water column of the Lake are governed predominantly by natural processes. Enhanced oxygen consumption in the Lake during summer season, high organic carbon concentrations and low redox potential result in occasional occurrence of anoxic conditions in the bottom layers. Speciation modelling showed that dissolved trace metals Cu, Pb and Zn, are mostly bound to organic matter, while Cd, Co and Ni are present predominantly as free ions and inorganic complexes. Trace metals removal from the water column and their retention in the sediment was found to depend on the nature of the relationship between specific metal and high proportion of organic matter (up to 9%) and inorganic phases, Fe-oxyhydroxydes or biogenic calcite. Surrounding karstic background, with occasional occurrences of red soil characterize deposited sediments as coarse grained and carbonate rich, whose elemental composition is affected by bathymetry of the basin and overall biological production.

  4. Ionic Transport Through Metal-Rich Organic Coatings

    Science.gov (United States)

    2016-08-19

    1 (2009): pp 1012-1013. 9. X. Zhang, F.Wang, Y. Du, “Effect of Nano-Sized Titanium Powder Addition on Corrosion Performance of Epoxy Coatings...choosing a coating is the substrate in question, the desired end use for the final product , and the environment in which the final product will be... product . Herein, we discuss the performance of one type of organic coating – metal-rich organic primer – as an ionic and electronic barrier for

  5. Ambient air monitoring for organic compounds, acids, and metals at Los Alamos National Laboratory, January 1991

    International Nuclear Information System (INIS)

    Williams, C.H.; Eberhart, C.F.

    1992-01-01

    Los Alamos National Laboratory (LANL) contracted Radian Corporation (Radian) to conduct a short-term, intensive air monitoring program whose goal was to estimate the impact of chemical emissions from LANL on the ambient air environment. A comprehensive emission inventory had identified more than 600 potential air contaminants in LANL's emissions. A subset of specific target chemicals was selected for monitoring: 20 organic vapors, 6 metals and 5 inorganic acid vapors. These were measured at 5 ground level sampling sites around LANL over seven consecutive days in January 1991. The sampling and analytical strategy used a combination of EPA and NIOSH methods modified for ambient air applications

  6. The relevance of metal organic frameworks (MOFs) in inorganic ...

    Indian Academy of Sciences (India)

    Vol. 124, No. 2, March 2012, pp. 339–353. c Indian Academy of Sciences. The relevance of metal organic frameworks (MOFs) in inorganic materials chemistry. SRINIVASAN NATARAJAN. ∗ .... preparing inorganic coordination compounds such as: .... (c) The connectivity between the heptanuclear cobalt cluster and the.

  7. SEQUESTERING AGENTS FOR ACTIVE CAPS - REMEDIATION OF METALS AND ORGANICS

    Energy Technology Data Exchange (ETDEWEB)

    Knox, A; Michael Paller, M; Danny D. Reible, D; Xingmao Ma, X; Ioana G. Petrisor, I

    2007-05-10

    This research evaluated organoclays, zeolites, phosphates, and a biopolymer as sequestering agents for inorganic and organic contaminants. Batch experiments were conducted to identify amendments and mixtures of amendments for metal and organic contaminants removal and retention. Contaminant removal was evaluated by calculating partitioning coefficients. Metal retention was evaluated by desorption studies in which residue from the removal studies was extracted with 1 M MgCl{sub 2} solution. The results indicated that phosphate amendments, some organoclays, and the biopolymer, chitosan, were very effective sequestering agents for metals in fresh and salt water. Organoclays were very effective sorbents for phenanthrene, pyrene, and benzo(a)pyrene. Partitioning coefficients for the organoclays were 3000-3500 ml g{sup -1} for benzo(a)pyrene, 400-450 ml g{sup -1} for pyrene, and 50-70 ml g{sup -1} for phenanthrene. Remediation of sites with a mixture of contaminants is more difficult than sites with a single contaminant because metals and organic contaminants have different fate and transport mechanisms in sediment and water. Mixtures of amendments (e.g., organoclay and rock phosphate) have high potential for remediating both organic and inorganic contaminants under a broad range of environmental conditions, and have promise as components in active caps for sediment remediation.

  8. The relevance of metal organic frameworks (MOFs) in inorganic ...

    Indian Academy of Sciences (India)

    The metal organic frameworks (MOFs) have evolved to be an important family and a corner stone for research in the area of inorganic chemistry. The progress made since 2000 has attracted researchers from other disciplines to actively engage themselves in this area. This cooperative synergy of different scientific believes ...

  9. Magnetic behaviour in metal-organic frameworks—Some recent ...

    Indian Academy of Sciences (India)

    The article describes the synthesis, structure and magnetic investigations of a series of metal-organic framework compounds formed with Mn+2 and Ni+2 ions. The structures, determined using the single crystal X-ray diffraction, indicated that the structures possess two- and three-dimensional structures with magnetically ...

  10. Levels of heavy metals, total hydrocarbon and organic carbon ...

    African Journals Online (AJOL)

    The sediment samples of River Ethiope and Ikpoba River were collected and extracted using n-hexane (BDH, England) and the resulting extracts were read at 460nm with a spectrophotometer. The heavy metal analysis was carried out by using atomic absorption spectroscopy. The organic carbon was determined by ...

  11. Metal Induced Luminescence Quenching in Organic Light Emitting Materials

    Science.gov (United States)

    Choong, Vi-En; Park, Yongsup; Gao, Yongli; Hsieh, Bing; Tang, Ching

    1997-03-01

    Organic materials have been demonstrated to have the necessary attributes for display applications. In typical organic light-emitting devices, metallic electrodes are used to inject charged carriers into the organic electroluminescent (EL) medium. We report severe photoluminescence (PL) quenching of organic thin films comprising of the most useful materials, namely tris-(8- hydroxyquinoline) aluminum and 1,4-bis[4-(3,5-di-tert- butylstyryl)styryl]benzene (4PV), upon sub-monolayer deposition of Al, Ag, and Ca in an ultra high vacuum environment. The severity of the luminescence quenching, which depends on the type of metal used, can greatly affect the EL device performance. For example, a sub-monolayer coverage of the various metals on a 300 /AA 4PV thin film can reduce the PL by as much as 50layer onto a metal substrate also exhibits PL quenching. An exciton diffusion length of 200 /AA can be estimated from the quenching data. Work supported in part by NSF DMR-9303019 and by DARPA DAAL 0196R9133.

  12. Organic matter and heavy metals in grey-water sludge

    African Journals Online (AJOL)

    ISSN 1816-7950 (On-line) = Water SA Vol. 36 No. 1 January 2010. 139. * To whom all correspondence should be addressed. ☎ (+45) 45 25 16 00; fax: (+45) 45 93 28 50; e-mail: eve@env.dtu.dk. Received 30 October2009; accepted in revised form 8 January 2010. Rapid communication. Organic matter and heavy metals ...

  13. Supramolecular Assembly of Calcium Metal - Organic Frameworks with Structural Transformation

    Czech Academy of Sciences Publication Activity Database

    Liang, P.-Ch.; Liu, H.-K.; Yeh, Ch.-T.; Lin, Ch.-H.; Zima, Vítězslav

    2011-01-01

    Roč. 11, č. 3 (2011), 699-708 ISSN 1528-7483 R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : metal - organic frameworks * calcium * structure Subject RIV: CA - Inorganic Chemistry Impact factor: 4.720, year: 2011

  14. Metal Organic Frameworks: Explorations and Design Strategies for MOF Synthesis

    KAUST Repository

    AbdulHalim, Rasha

    2016-11-27

    Metal-Organic Frameworks (MOFs) represent an emerging new class of functional crystalline solid-state materials. In the early discovery of this now rapidly growing class of materials significant challenges were often encountered. However, MOFs today, with its vast structural modularity, reflected by the huge library of the available chemical building blocks, and exceptional controlled porosity, stand as the most promising candidate to address many of the overbearing societal challenges pertaining to energy and environmental sustainability. A variety of design strategies have been enumerated in the literature which rely on the use of predesigned building blocks paving the way towards potentially more predictable structures. The two major design strategies presented in this work are the molecular building block (MBB) and supermolecular building block (SBB) -based approaches for the rationale assembly of functional MOF materials with the desired structural features. In this context, we targeted two highly connected MOF platforms, namely rht-MOF and shp-MOF. These two MOF platforms are classified based on their topology, defined as the underlying connectivity of their respective net, as edge transitive binodal nets; shp being (4,12)-connected net and rht being (3,24)-connected net. These highly connected nets were deliberately targeted due to the limited number of possible nets for connecting their associated basic building units. Two highly porous materials were designed and successfully constructed; namely Y-shp-MOF-5 and rht-MOF-10. The Y-shp-MOF-5 features a phenomenal water stability with an exquisite behavior when exposed to water, positioning this microporous material as the best adsorbent for moisture control applications. The shp-MOF platform proved to be modular to ligand functionalization and thus imparting significant behavioral changes when hydrophilic and hydrophobic functionalized ligands were introduced on the resultant MOF. On the other hand, rht

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

    Science.gov (United States)

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

    2012-03-01

    The agricultural use of anaerobically digested sewage sludge (ADSS) as stable, mature compost implies knowing its total content in heavy metals and their bioavailability. This depends not only on the initial characteristics of the composted substrates but also on the organic matter transformations during composting which may influence the chemical form of the metals and their bioavailability. The objective of this work was to examine the relationships between the changes in the organic matter content and humus fractions, and the bioavailability of heavy metals. A detailed sampling at 0, 14, 84, and 140 days of the composting process was performed to measure C contents in humic acids (HAs), fulvic acids, (FAs) and humin, the total content of Zn, Pb, Cu, Ni, and Cd, and also their distribution into mobile and mobilisable (MB), and low bioavailability (LB) forms. Significant changes of C contents in HA, FA, and Humin, and in the FA/HA, HA/Humin and C(humus)/TOC ratios were observed during composting. The MB and LB fractions of each metal also varied significantly during composting. The MB fraction increased for Zn, Cu, Ni, and Cd, and the LB fraction increased for Pb. Stepwise linear regressions and quadratic curve estimation conducted on the MB and LB fractions of each metal as dependent on the measured organic variables suggested that Zn bioavailability was mainly associated to percentage of C in FAs. Bioavailability of Cu, Ni and Cd during composting was associated to humin and HAs. Pb concentration increased in the LB form, and its variations followed a quadratic function with the C(humus)/TOC ratio. Our results suggest that the composting process renders the metals in more available forms. The main forms of metal binding in the sludge and their availability in the final compost may be better described when metal fractionation obtained in sequential extraction and humus fractionation during composting are considered together. Copyright © 2011 Elsevier Ltd. All

  16. Transport and Fate of Volatile Organic Chemical in Soils

    DEFF Research Database (Denmark)

    Petersen, Lis Wollesen

    Recently much attention has been paid to the behavior of volatile organic chemicals (VOCs) in the environment. This is due to the fact that the environmental pollution with these hazardous chemicals has drastically increased during the last decades. The present study is limited to consider...... the transport and fate of VOCs in the gaseous phase, thus contributing to the overall understanding of VOCs behavior in soil, which eventually will facilitate future cleanup....

  17. Thermodynamics of Pore Filling Metal Clusters in Metal Organic Frameworks: Pd in UiO-66

    DEFF Research Database (Denmark)

    Vilhelmsen, Lasse; Sholl, David S.

    2012-01-01

    Metal organic frameworks (MOFs) have experimentally been demonstrated to be capable of supporting isolated transition-metal clusters, but the stability of these clusters with respect to aggregation is unclear. In this letter we use a genetic algorithm together with density functional theory...... calculations to predict the structure of Pd clusters in UiO-66. The cluster sizes examined are far larger than those in any previous modeling studies of metal clusters in MOFs and allow us to test the hypothesis that the physically separated cavities in UiO-66 could stabilize isolated Pd clusters. Our...

  18. Chemical Annealing of Zinc Tetraphenylporphyrin Films: Effects on Film Morphology and Organic Photovoltaic Performance

    KAUST Repository

    Trinh, Cong

    2012-07-10

    We present a chemical annealing process for organic thin films. In this process, a thin film of a molecular material, such as zinc tetraphenylporphyrin (ZnTPP), is exposed to a vapor of nitrogen-based ligand (e.g., pyrazine, pz, and triazine, tz), forming a film composed of the metal-ligand complex. Fast and quantitative formation of the complex leads to marked changes in the morphology and optical properties of the film. X-ray diffraction studies show that the chemical annealing process converts amorphous ZnTPP films to crystalline ZnTPP•ligand films, whose porphryin planes lie nearly parallel to the substrate (average deviation is 8° for the ZnTPP•pz film). Organic solar cells were prepared with ZnTPP donor and C 60 acceptor layers. Devices were prepared with and without chemical annealing of the ZnTPP layer with a pyrazine ligand. The devices with chemically annealed ZnTPP donor layer show an increase in short-circuit current (J SC) and fill factor (FF) relative to analogous unannealed devices, presumably because of enhanced exciton diffusion length and improved charge conductivity. The open circuit voltages (V OC) of the chemically annealed devices are lower than their unannealed counterpart because of enhanced polaron pair recombination at the donor/acceptor heterojunction. A net improvement of 5-20% in efficiency has been achieved, after chemical annealing of ZnTPP films with pyrazine. © 2012 American Chemical Society.

  19. Predicting the bioconcentration factor of highly hydrophobic organic chemicals.

    Science.gov (United States)

    Garg, Rajni; Smith, Carr J

    2014-07-01

    Bioconcentration refers to the process of uptake and buildup of chemicals in living organisms. Experimental measurement of bioconcentration factor (BCF) is time-consuming and expensive, and is not feasible for a large number of chemicals of regulatory concern. Quantitative structure-activity relationship (QSAR) models are used for estimating BCF values to help in risk assessment of a chemical. This paper presents the results of a QSAR study conducted to address an important problem encountered in the prediction of the BCF of highly hydrophobic chemicals. A new QSAR model is derived using a dataset of diverse organic chemicals previously tested in a United States Environmental Protection Agency laboratory. It is noted that the linear relationship between the BCF and hydrophobic parameter, i.e., calculated octanol-water partition coefficient (ClogP), breaks down for highly hydrophobic chemicals. The parabolic QSAR equation, log BCF=3.036 ClogP-0.197 ClogP(2)-0.808 MgVol (n=28, r(2)=0.817, q(2)=0.761, s=0.558) (experimental log BCF range=0.44-5.29, ClogP range=3.16-11.27), suggests that a non-linear relationship between BCF and the hydrophobic parameter, along with inclusion of additional molecular size, weight and/or volume parameters, should be considered while developing a QSAR model for more reliable prediction of the BCF of highly hydrophobic chemicals. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. Chemically synthesized metal-oxide-metal segmented nanowires with high ferroelectric response

    Energy Technology Data Exchange (ETDEWEB)

    Herderick, Edward D; Padture, Nitin P [Department of Materials Science and Engineering, Center for Emergent Materials, Ohio State University, Columbus, OH 43210 (United States); Polomoff, Nicholas A; Huey, Bryan D, E-mail: padture.1@osu.edu [Department of Chemical, Materials, and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

    2010-08-20

    A chemical synthesis method is presented for the fabrication of high-definition segmented metal-oxide-metal (MOM) nanowires in two different ferroelectric oxide systems: Au-BaTiO{sub 3}-Au and Au-PbTiO{sub 3}-Au. This method entails electrodeposition of segmented nanowires of Au-TiO{sub 2}-Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO{sub 2} segments into BaTiO{sub 3} or PbTiO{sub 3} segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.

  1. 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.

  2. A Stable Metal-Organic Framework Featuring a Local Buffer Environment for Carbon Dioxide Fixation.

    Science.gov (United States)

    He, Hongming; Sun, Qi; Gao, Wenyang; Perman, Jason A; Sun, Fuxing; Zhu, Guangshan; Aguila, Briana; Forrest, Katherine; Space, Brian; Ma, Shengqian

    2018-04-16

    A majority of metal-organic frameworks (MOFs) fail to preserve their physical and chemical properties after exposure to acidic, neutral, or alkaline aqueous solutions, therefore limiting their practical applications in many areas. The strategy demonstrated herein is the design and synthesis of an organic ligand that behaves as a buffer to drastically boost the aqueous stability of a porous MOF (JUC-1000), which maintains its structural integrity at low and high pH values. The local buffer environment resulting from the weak acid-base pairs of the custom-designed organic ligand also greatly facilitates the performance of JUC-1000 in the chemical fixation of carbon dioxide under ambient conditions, outperforming a series of benchmark catalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Characterization of magnetite-organic complex nanoparticles by metal-reducing bacteria.

    Science.gov (United States)

    Kim, Yumi; Jang, Heedong; Suh, Yongjae; Roh, Yul

    2011-08-01

    Magnetite nanoparticles exhibit clear technological potential for biomedical applications. The objectives of this study were to synthesize magnetite-organic complex nanoparticles through the use of metal-reducing bacteria and characterize the mineralogical and surface chemical properties of these nanoparticles as well as to test their potential applications in biomedical technology with regards to their protein immobilization capacity. The microbially formed magnetite nanoparticles had a size of around 10 nm with a spherical shape and were coated with organics containing an abundance of reactive carboxyl groups without any chemical process for functionalizing them. These microbial processes may lead to a simple preparation of functional magnetite-organic complex nanoparticles which have benefits for biomedical applications.

  4. Metal Nanoparticles Protected with Monolayers: Applications for Chemical Vapor Sensing and Gas Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Nelson, David A.; Skaggs, Rhonda L.; Synovec, Robert E.; Gross, Gwen M.

    2004-03-31

    Nanoparticles and nanoparticle-based materials are of considerable interest for their unique properties and their potential for use in a variety of applications. Metal nanoparticles, in which each particle’s surface is coated with a protective organic monolayer, are of particular interest because the surface monolayer stabilizes them relative to aggregation and they can be taken up into solutions.(1-4) As a result they can be processed into thin films for device applications. We will refer to these materials as monolayer-protected nanoparticles, or MPNs. Typically the metal is gold, the organic layer is a self-assembled thiol layer, and this composition will be assumed throughout the remainder of this chapter. A diversity of materials and properties is readily accessible by straightforward synthetic procedures, either by the structures of the monolayer-forming thiols used in the synthesis or by post-synthetic modifications of the monolayers. A particularly promising application for these materials is as selective layers on chemical vapor sensors. In this role, the thin film of MPNs on the device surface serves to collect and concentrate gas molecules at the sensor’s surface. Their sorptive properties also lend them to use as new nanostructured gas chromatographic stationary phases. This chapter will focus on the sorptive properties of MPNs as they relate to chemical sensors and gas chromatography.

  5. Expanded Organic Building Units for the Construction of Highly Porous Metal-Organic Frameworks

    NARCIS (Netherlands)

    Kong, G.Q.; Han, Z.D.; He, Y.; Qu, S.; Zhou, W.; Yildirim, T.; Krishna, R.; Zou, C.; Chen, B.; Wu, C.D.

    2013-01-01

    wo new organic building units that contain dicarboxylate sites for their self-assembly with paddlewheel [Cu2(CO2)4] units have been successfully developed to construct two isoreticular porous metal-organic frameworks (MOFs), ZJU-35 and ZJU-36, which have the same tbo topologies (Reticular Chemistry

  6. Combinations of Aminocatalysts and Metal Catalysts: A Powerful Cooperative Approach in Selective Organic Synthesis.

    Science.gov (United States)

    Afewerki, Samson; Córdova, Armando

    2016-11-23

    The cooperation and interplay between organic and metal catalyst systems is of utmost importance in nature and chemical synthesis. Here innovative and selective cooperative catalyst systems can be designed by combining two catalysts that complement rather than inhibit one another. This refined strategy can permit chemical transformations unmanageable by either of the catalysts alone. This review summarizes innovations and developments in selective organic synthesis that have used cooperative dual catalysis by combining simple aminocatalysts with metal catalysts. Considerable efforts have been devoted to this fruitful field. This emerging area employs the different activation modes of amine and metal catalysts as a platform to address challenging reactions. Here, aminocatalysis (e.g., enamine activation catalysis, iminium activation catalysis, single occupied molecular orbital (SOMO) activation catalysis, and photoredox activation catalysis) is employed to activate unreactive carbonyl substrates. The transition metal catalyst complements by activating a variety of substrates through a range of interactions (e.g., electrophilic π-allyl complex formation, Lewis acid activation, allenylidene complex formation, photoredox activation, C-H activation, etc.), and thereby novel concepts within catalysis are created. The inclusion of heterogeneous catalysis strategies allows for "green" chemistry development, catalyst recyclability, and the more eco-friendly synthesis of valuable compounds.

  7. Bias-induced insulator-metal transition in organic electronics

    Science.gov (United States)

    Wei, J. H.; Xie, S. J.; Mei, L. M.; Yan, YiJing

    2007-07-01

    The authors investigate the bias-induced insulator-metal transition in organic electronics devices on the basis of the Su-Schrieffer-Heeger model [W. P. Su et al., Phys. Rev. B 22, 2099 (1980)] combined with the nonequilibrium Green's function formalism. The insulator-metal transition is explained with the energy level crossover that eliminates the Peierls phase [R. Peierls, Quantum Theory of Solids (Oxford University Press, Oxford, 1955)] and delocalizes the electron states near the threshold voltage. This may account for the experimental observations on the devices that exhibit intrinsic bistable conductance switching with large on-off ratio.

  8. Synthesis of borohydrides of rare earth metals by mechanic-chemical methods

    International Nuclear Information System (INIS)

    Gafurov, B.A.; Nasrulloeva, D.Kh.; Khakyorov, I.Z.; Saidov, V.Ya.

    2010-01-01

    Present article is devoted to synthesis of borohydrides of rare earth metals by mechanic-chemical methods. The borohydrides of rare earth metals were obtained by means of mechanic-chemical methods. Physicochemical properties of obtained lanthanoid borohydrides were studied by means of X-ray phase analysis.

  9. Chemical speciation of heavy metals in sandy soils in relation to availability and mobility

    NARCIS (Netherlands)

    Temminghoff, E.J.M.

    1998-01-01

    The environmental risk of heavy metals which are present in soil at a certain total content is highly dependent on soil properties. Chemical speciation is a comprehensive term for the distribution of heavy metals over all possible chemical forms (species) in soil solution and in the solid

  10. Physico-chemical changes in dissolved organic matters in the rhizosphere of plants grown in soil amended with organic wastes: an in-situ investigation.

    Science.gov (United States)

    Djae, Tanalou; Bravin, Matthieu; Garnier, Cédric; Mayen, Jean-Fabien; Doelsch, Emmanuel

    2014-05-01

    In agricultural context, prerequisite condition to forecast trace metal phytodisponibility is to evaluate trace metal speciation in the rhizosphere solution, especially in soil amended with organic wastes. The most advanced trace metal speciation models (e.g. WHAM, NICA-DONNAN) take into account dissolved organic matter (DOM) reactivity toward trace metals. Generally, the scientific community uses, a fixed percentage of DOM reactivity, usually of 40 % to 80 %, to predict trace metal speciation. However, recent studies have demonstrated that the binding capacity of DOM towards trace metals is much larger than expected. The aim of our study was to investigate the mechanisms supporting the variability in DOM reactivity by assessing the physico-chemical changes of DOM in the bulk-soil and rhizosphere in context of agricultural recycling of organic wastes. An in-situ experiment was conducted in Reunion Island (Indian Ocean). Two plant species, i.e. a graminaceous species the fescue (Festuca rubra) and a dicotyledonous species the tomato (Lycopersicon esculentum), were grown on a soil where we applied two types of organic wastes (pig manure compost and poultry manure compost) at three rates and a mineral fertilizer. Following this experiment, the soil either adhering to the roots (i.e. rhizosphere) or not (i.e. bulk-soil) was sampled and the soil solution was recovered by chemical extraction. DOM concentration, total acidity and DOM fluorescence were measured. Root activities and organic wastes induced variations in the physico-chemical parameters of DOM. DOM concentration tended to increase in bulk-soil with increasing organic waste application rate. DOM concentrations measured in rhizosphere are significantly greater than those in the bulk-soil especially when organic wastes were applied to soil. Preliminary results allow us to observe a decrease in the density of carboxylic-like (pKa

  11. Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

    Science.gov (United States)

    Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

    1990-01-01

    A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

  12. Effects of different organic materials and chemical fertilizers on ...

    African Journals Online (AJOL)

    This study was conducted under greenhouse conditions to investigate the effects of applied nutrients such as six organic materials (gyttja, alsil, humic acid, sea moss, straw and peat) and two chemical fertilizers (15-15-15, and 20-20-0) with different dosages on nutrient uptaking ability of one-year old and 7 cm long ...

  13. The chemistry of metal-organic frameworks for CO2 capture, regeneration and conversion

    Science.gov (United States)

    Trickett, Christopher A.; Helal, Aasif; Al-Maythalony, Bassem A.; Yamani, Zain H.; Cordova, Kyle E.; Yaghi, Omar M.

    2017-08-01

    The carbon dioxide challenge is one of the most pressing problems facing our planet. Each stage in the carbon cycle — capture, regeneration and conversion — has its own materials requirements. Recent work on metal-organic frameworks (MOFs) demonstrated the potential and effectiveness of these materials in addressing this challenge. In this Review, we identify the specific structural and chemical properties of MOFs that have led to the highest capture capacities, the most efficient separations and regeneration processes, and the most effective catalytic conversions. The interior of MOFs can be designed to have coordinatively unsaturated metal sites, specific heteroatoms, covalent functionalization, other building unit interactions, hydrophobicity, porosity, defects and embedded nanoscale metal catalysts with a level of precision that is crucial for the development of higher-performance MOFs. To realize a total solution, it is necessary to use the precision of MOF chemistry to build more complex materials to address selectivity, capacity and conversion together in one material.

  14. On the occurrence of metallic character in the periodic table of the chemical elements.

    Science.gov (United States)

    Hensel, Friedrich; Slocombe, Daniel R; Edwards, Peter P

    2015-03-13

    The classification of a chemical element as either 'metal' or 'non-metal' continues to form the basis of an instantly recognizable, universal representation of the periodic table (Mendeleeff D. 1905 The principles of chemistry, vol. II, p. 23; Poliakoff M. & Tang S. 2015 Phil. Trans. R. Soc. A 373: , 20140211). Here, we review major, pre-quantum-mechanical innovations (Goldhammer DA. 1913 Dispersion und Absorption des Lichtes; Herzfeld KF. 1927 Phys. Rev. 29: , 701-705) that allow an understanding of the metallic or non-metallic status of the chemical elements under both ambient and extreme conditions. A special emphasis will be placed on recent experimental advances that investigate how the electronic properties of chemical elements vary with temperature and density, and how this invariably relates to a changing status of the chemical elements. Thus, the prototypical non-metals, hydrogen and helium, becomes metallic at high densities; and the acknowledged metals, mercury, rubidium and caesium, transform into their non-metallic forms at low elemental densities. This reflects the fundamental fact that, at temperatures above the absolute zero of temperature, there is therefore no clear dividing line between metals and non-metals. Our conventional demarcation of chemical elements as metals or non-metals within the periodic table is of course governed by our experience of the nature of the elements under ambient conditions. Examination of these other situations helps us to examine the exact divisions of the chemical elements into metals and non-metals (Mendeleeff D. 1905 The principles of chemistry, vol. II, p. 23). © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  15. Trophic magnification of organic chemicals: A global synthesis

    Science.gov (United States)

    Walter, W. David; Jardine, T.D.; Cade, Brian S.; Kidd, K.A.; Muir, D.C.G.; Leipzig-Scott, Peter C.

    2016-01-01

    Production of organic chemicals (OCs) is increasing exponentially, and some OCs biomagnify through food webs to potentially toxic levels. Biomagnification under field conditions is best described by trophic magnification factors (TMFs; per trophic level change in log-concentration of a chemical) which have been measured for more than two decades. Syntheses of TMF behavior relative to chemical traits and ecosystem properties are lacking. We analyzed >1500 TMFs to identify OCs predisposed to biomagnify and to assess ecosystem vulnerability. The highest TMFs were for OCs that are slowly metabolized by animals (metabolic rate kM compounds, regardless of KOW, and lowest for chemicals with rapid transformation rates (kM > 0.2 day–1). This probabilistic model provides a new global tool for screening existing and new OCs for their biomagnification potential.

  16. Carotenoids Database: structures, chemical fingerprints and distribution among organisms.

    Science.gov (United States)

    Yabuzaki, Junko

    2017-01-01

    To promote understanding of how organisms are related via carotenoids, either evolutionarily or symbiotically, or in food chains through natural histories, we built the Carotenoids Database. This provides chemical information on 1117 natural carotenoids with 683 source organisms. For extracting organisms closely related through the biosynthesis of carotenoids, we offer a new similarity search system 'Search similar carotenoids' using our original chemical fingerprint 'Carotenoid DB Chemical Fingerprints'. These Carotenoid DB Chemical Fingerprints describe the chemical substructure and the modification details based upon International Union of Pure and Applied Chemistry (IUPAC) semi-systematic names of the carotenoids. The fingerprints also allow (i) easier prediction of six biological functions of carotenoids: provitamin A, membrane stabilizers, odorous substances, allelochemicals, antiproliferative activity and reverse MDR activity against cancer cells, (ii) easier classification of carotenoid structures, (iii) partial and exact structure searching and (iv) easier extraction of structural isomers and stereoisomers. We believe this to be the first attempt to establish fingerprints using the IUPAC semi-systematic names. For extracting close profiled organisms, we provide a new tool 'Search similar profiled organisms'. Our current statistics show some insights into natural history: carotenoids seem to have been spread largely by bacteria, as they produce C30, C40, C45 and C50 carotenoids, with the widest range of end groups, and they share a small portion of C40 carotenoids with eukaryotes. Archaea share an even smaller portion with eukaryotes. Eukaryotes then have evolved a considerable variety of C40 carotenoids. Considering carotenoids, eukaryotes seem more closely related to bacteria than to archaea aside from 16S rRNA lineage analysis. : http://carotenoiddb.jp. © The Author(s) 2017. Published by Oxford University Press.

  17. Transect studies on pine litter organic matter: decomposition and chemical properties of upper soil layers in Polish forests

    Science.gov (United States)

    Alicja Breymeyer; Marek Degorski; David Reed

    1998-01-01

    The relationship between litter decomposition rate, some chemical properties of upper soil layers (iron, manganese, zinc, copper, lead, mercury, nickel, chrome in humus-mineral horizon-A), and litter (the same eight elements in needle litter fraction) in pine forests of Poland was studied. Heavy metal content in organic-mineral horizon of soils was highly correlated...

  18. Signature of Metallic Behavior in the Metal-Organic Frameworks M3(hexaiminobenzene)2(M = Ni, Cu).

    Science.gov (United States)

    Dou, Jin-Hu; Sun, Lei; Ge, Yicong; Li, Wenbin; Hendon, Christopher H; Li, Ju; Gul, Sheraz; Yano, Junko; Stach, Eric A; Dincă, Mircea

    2017-10-04

    The two-dimensionally connected metal-organic frameworks (MOFs) Ni 3 (HIB) 2 and Cu 3 (HIB) 2 (HIB = hexaiminobenzene) are bulk electrical conductors and exhibit ultraviolet-photoelectron spectroscopy (UPS) signatures expected of metallic solids. Electronic band structure calculations confirm that in both materials the Fermi energy lies in a partially filled delocalized band. Together with additional structural characterization and microscopy data, these results represent the first report of metallic behavior and permanent porosity coexisting within a metal-organic framework.

  19. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids.

    Science.gov (United States)

    Nandasiri, Manjula I; Liu, Jian; McGrail, B Peter; Jenks, Jeromy; Schaef, Herbert T; Shutthanandan, Vaithiyalingam; Nie, Zimin; Martin, Paul F; Nune, Satish K

    2016-06-15

    Metal-organic heat carriers (MOHCs) are recently developed nanofluids containing metal-organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with the intrinsic nanoMIL-101(Cr) and the properties depended on the amount of GO added. MIL-101(Cr)/GO in methanol exhibited a significant increase in the thermal conductivity (by approximately 50%) relative to that of the intrinsic nanoMIL-101(Cr) in methanol. The thermal conductivity of the base fluid (methanol) was increased by about 20%. The increase in the thermal conductivity of nanoMIL-101(Cr) MOHCs due to GO functionalization is explained using a classical Maxwell model.

  20. An Ising model for metal-organic frameworks

    Science.gov (United States)

    Höft, Nicolas; Horbach, Jürgen; Martín-Mayor, Victor; Seoane, Beatriz

    2017-08-01

    We present a three-dimensional Ising model where lines of equal spins are frozen such that they form an ordered framework structure. The frame spins impose an external field on the rest of the spins (active spins). We demonstrate that this "porous Ising model" can be seen as a minimal model for condensation transitions of gas molecules in metal-organic frameworks. Using Monte Carlo simulation techniques, we compare the phase behavior of a porous Ising model with that of a particle-based model for the condensation of methane (CH4) in the isoreticular metal-organic framework IRMOF-16. For both models, we find a line of first-order phase transitions that end in a critical point. We show that the critical behavior in both cases belongs to the 3D Ising universality class, in contrast to other phase transitions in confinement such as capillary condensation.

  1. Metal-organic frameworks as selectivity regulators for hydrogenation reactions.

    Science.gov (United States)

    Zhao, Meiting; Yuan, Kuo; Wang, Yun; Li, Guodong; Guo, Jun; Gu, Lin; Hu, Wenping; Zhao, Huijun; Tang, Zhiyong

    2016-11-03

    Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe 3+ , Cr 3+ or both (known as MIL-101; refs 19, 20, 21) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon-oxygen rather than the carbon-carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design

  2. Ultrathin metal-organic framework array for efficient electrocatalytic water splitting

    Science.gov (United States)

    Duan, Jingjing; Chen, Sheng; Zhao, Chuan

    2017-06-01

    Two-dimensional metal-organic frameworks represent a family of materials with attractive chemical and structural properties, which are usually prepared in the form of bulk powders. Here we show a generic approach to fabricate ultrathin nanosheet array of metal-organic frameworks on different substrates through a dissolution-crystallization mechanism. These materials exhibit intriguing properties for electrocatalysis including highly exposed active molecular metal sites owning to ultra-small thickness of nanosheets, improved electrical conductivity and a combination of hierarchical porosity. We fabricate a nickel-iron-based metal-organic framework array, which demonstrates superior electrocatalytic performance towards oxygen evolution reaction with a small overpotential of 240 mV at 10 mA cm-2, and robust operation for 20,000 s with no detectable activity decay. Remarkably, the turnover frequency of the electrode is 3.8 s-1 at an overpotential of 400 mV. We further demonstrate the promise of these electrodes for other important catalytic reactions including hydrogen evolution reaction and overall water splitting.

  3. Effects of ultrasound on properties of ni-metal organic framework nanostructures

    Directory of Open Access Journals (Sweden)

    Abbas Pardakhty

    2016-10-01

    Full Text Available Objective(s: According to the unique properties of magnetic nanoparticles, Nickel Metal-Organic Frameworks (MOF was synthesized successfully by ultrasound irradiation. Metal-organic frameworks (MOFs are organic–inorganic hybrid extended networks that are constructed via covalent linkages between metal ions/metal clusters and organic ligands called a linker. Materials and Methods: The nanoparticles were synthesized by Ultrasound  Method Under a synthesis conditions, All chemicals were used as received without further purification. Scanning electron microscopy (SEM images were obtained on LEO- 1455VP equipped with an energy dispersive X-ray spectroscopy at university of Kashan in Iran. Transition electron microscopy (TEM images were obtained on EM208 Philips transmission electron microscope with an accelerating voltage of 200 kV. Results: Results showed that Ni-MOF synthesized by this method, had smaller particle size distribution and It was found that the different kinds of ligand leads to preparation products with different morphologies and textural properties. Moreover, ultrasound irradiation method has significant effect on microstructures of as-synthesized MOFs and can improve their textural properties compared to method without using hydrothermal route.The XRD patterns of the samples obtained from ultrasound irradiation was well matched with that of as-prepared Ni-MOF by solvothermal method. Conclusion: This rapid method of ultrasonic radiation as compared to the classical solvothermal synthesis, showed promising results in terms of size distribution, surface area, pore diameter and pore volume.

  4. Sinter-Resistant Platinum Catalyst Supported by Metal-Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Soo [Materials Science Division, Argonne National Lab, 9700 S Cass Ave. Argonne IL 60439 USA; Nanophotonics Center, Korea Institute of Science and Technology, Seoul 02792 South Korea; Li, Zhanyong [Department of Chemistry, Northwestern University, 2145 Sheridan Rd. Evanston IL 60208 USA; Zheng, Jian [Institute for Integrated Catalysis, Pacific Northwest National Lab, P.O. Box 999 Richland WA 99352 USA; Platero-Prats, Ana E. [X-ray Science Division, Argonne National Lab, 9700 S Cass Ave. Argonne IL 60439 USA; Mavrandonakis, Andreas [Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis MN 55455 USA; Pellizzeri, Steven [Chemical and Biomolecular Engineering, Clemson University, 205 Earle Hall Clemson SC 29634 USA; Ferrandon, Magali [Chemical Sciences and Engineering Division, Argonne National Lab, 9700 S. Cass Ave. Argonne IL 60439 USA; Vjunov, Aleksei [Institute for Integrated Catalysis, Pacific Northwest National Lab, P.O. Box 999 Richland WA 99352 USA; Gallington, Leighanne C. [X-ray Science Division, Argonne National Lab, 9700 S Cass Ave. Argonne IL 60439 USA; Webber, Thomas E. [Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis MN 55455 USA; Vermeulen, Nicolaas A. [Department of Chemistry, Northwestern University, 2145 Sheridan Rd. Evanston IL 60208 USA; Penn, R. Lee [Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis MN 55455 USA; Getman, Rachel B. [Chemical and Biomolecular Engineering, Clemson University, 205 Earle Hall Clemson SC 29634 USA; Cramer, Christopher J. [Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis MN 55455 USA; Chapman, Karena W. [X-ray Science Division, Argonne National Lab, 9700 S Cass Ave. Argonne IL 60439 USA; Camaioni, Donald M. [Institute for Integrated Catalysis, Pacific Northwest National Lab, P.O. Box 999 Richland WA 99352 USA; Fulton, John L. [Institute for Integrated Catalysis, Pacific Northwest National Lab, P.O. Box 999 Richland WA 99352 USA; Lercher, Johannes A. [Institute for Integrated Catalysis, Pacific Northwest National Lab, P.O. Box 999 Richland WA 99352 USA; Department of Chemistry and Catalysis Research Institute, Technische Universität München, Lichtenbergstrasse 4 85748 Garching Germany; Farha, Omar K. [Department of Chemistry, Northwestern University, 2145 Sheridan Rd. Evanston IL 60208 USA; Hupp, Joseph T. [Materials Science Division, Argonne National Lab, 9700 S Cass Ave. Argonne IL 60439 USA; Department of Chemistry, Northwestern University, 2145 Sheridan Rd. Evanston IL 60208 USA; Martinson, Alex B. F. [Materials Science Division, Argonne National Lab, 9700 S Cass Ave. Argonne IL 60439 USA

    2018-01-02

    Installed on the zirconia nodes of a metal-organic framework (MOF) NU-1000 via targeted vapor-phase synthesis. The catalytic Pt clusters, site-isolated by organic linkers, are shown to exhibit high catalytic activity for ethylene hydrogenation while exhibiting resistance to sintering up to 200 degrees C. In situ IR spectroscopy reveals the presence of both single atoms and few-atom clusters that depend upon synthesis conditions. Operando X-ray absorption spectroscopy and Xray pair distribution analyses reveal unique changes in chemical bonding environment and cluster size stability while on stream. Density functional theory calculations elucidate a favorable reaction pathway for ethylene hydrogenation with the novel catalyst. These results provide evidence that atomic layer deposition (ALD) in MOFs is a versatile approach to the rational synthesis of size-selected clusters, including noble metals, on a high surface area support.

  5. Nano-architecture of metal-organic frameworks

    Science.gov (United States)

    Milichko, Valentin A.; Zalogina, Anastasiia; Mingabudinova, Leila R.; Vinogradov, Alexander V.; Ubyivovk, Evgeniy; Krasilin, Andrei A.; Mukhin, Ivan; Zuev, Dmitry A.; Makarov, Sergey V.; Pidko, Evgeny A.

    2017-09-01

    Change the shape and size of materials supports new functionalities never found in the sources. This strategy has been recently applied for porous crystalline materials - metal-organic frameworks (MOFs) to create hollow nanoscale structures or mesostructures with improved functional properties. However, such structures are characterized by amorphous state or polycrystallinity which limits their applicability. Here we follow this strategy to create such nano- and mesostructures with perfect crystallinity and new photonics functionalities by laser or focused ion beam fabrication.

  6. Metal complex modified azo polymers for multilevel organic memories

    Science.gov (United States)

    Ma, Yong; Chen, Hong-Xia; Zhou, Feng; Li, Hua; Dong, Huilong; Li, You-Yong; Hu, Zhi-Jun; Xu, Qing-Feng; Lu, Jian-Mei

    2015-04-01

    Multilevel organic memories have attracted considerable interest due to their high capacity of data storage. Despite advances, the search for multilevel memory materials still remains a formidable challenge. Herein, we present a rational design and synthesis of a class of polymers containing an azobenzene-pyridine group (PAzo-py) and its derivatives, for multilevel organic memory storage. In this design, a metal complex (M(Phen)Cl2, M = Cu, Pd) is employed to modify the HOMO-LUMO energy levels of azo polymers, thereby converting the memory state from binary to ternary. More importantly, this approach enables modulating the energy levels of azo polymers by varying the coordination metal ions. This makes the achievement of high performance multilevel memories possible. The ability to tune the bandgap energy of azo polymers provides new exciting opportunities to develop new materials for high-density data storage.Multilevel organic memories have attracted considerable interest due to their high capacity of data storage. Despite advances, the search for multilevel memory materials still remains a formidable challenge. Herein, we present a rational design and synthesis of a class of polymers containing an azobenzene-pyridine group (PAzo-py) and its derivatives, for multilevel organic memory storage. In this design, a metal complex (M(Phen)Cl2, M = Cu, Pd) is employed to modify the HOMO-LUMO energy levels of azo polymers, thereby converting the memory state from binary to ternary. More importantly, this approach enables modulating the energy levels of azo polymers by varying the coordination metal ions. This makes the achievement of high performance multilevel memories possible. The ability to tune the bandgap energy of azo polymers provides new exciting opportunities to develop new materials for high-density data storage. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00871a

  7. Controlling Thermal Expansion: A Metal?Organic Frameworks Route

    OpenAIRE

    Balestra, Salvador R. G.; Bueno-Perez, Rocio; Hamad, Said; Dubbeldam, David; Ruiz-Salvador, A. Rabdel; Calero, Sofia

    2016-01-01

    Controlling thermal expansion is an important, not yet resolved, and challenging problem in materials research. A conceptual design is introduced here, for the first time, for the use of metal?organic frameworks (MOFs) as platforms for controlling thermal expansion devices that can operate in the negative, zero, and positive expansion regimes. A detailed computer simulation study, based on molecular dynamics, is presented to support the targeted application. MOF-5 has been selected as model m...

  8. Structural Origins of Scintillation: Metal Organic Frameworks as a Nanolaboratory

    Science.gov (United States)

    2016-06-01

    discrimination (PSD), for which the prompt component of the scintillation response is quenched for high specific energy loss (dE/dX) particles such as protons...for neutron discrimination (LDRD, $250k/year, FY10) - MOF-based scintillators (NA-22, ~600k / year, FY10-FY12) - Triplet-Harvesting doped plastic ...Structural Origins of Scintillation : Metal Organic Frameworks as a Nanolaboratory Distribution Statement A. Approved for public release

  9. Cerium-based metal organic frameworks with UiO-66 architecture: synthesis, properties and redox catalytic activity.

    Science.gov (United States)

    Lammert, Martin; Wharmby, Michael T; Smolders, Simon; Bueken, Bart; Lieb, Alexandra; Lomachenko, Kirill A; Vos, Dirk De; Stock, Norbert

    2015-08-14

    A series of nine Ce(iv)-based metal organic frameworks with the UiO-66 structure containing linker molecules of different sizes and functionalities were obtained under mild synthesis conditions and short reaction times. Thermal and chemical stabilities were determined and a Ce-UiO-66-BDC/TEMPO system was successfully employed for the aerobic oxidation of benzyl alcohol.

  10. Toxicity of selected organic chemicals to the earthworm Eisenia fetida

    Energy Technology Data Exchange (ETDEWEB)

    Neuhauser, E.F.; Loehr, R.C.; Malecki, M.R.; Milligan, D.L.; Durkin, P.R.

    A number of methods recently have been developed to biologically evaluate the impact of man's activities on soil ecosystems. Two test methods, the 2-d contact test and the 14-d artificial soil test, were used to evaluate the impact of six major classes of organic chemicals on the earthworm Eisenia fetida (Savigny). Of the organic chemicals tested, phenols and amines were the most toxic to the worms, followed in descending order of toxicity by the substituted aromatics, halogenated aliphatics, polycyclic aromatic hydrocarbons, and phthalates. No relationship was found between earthworm toxicity as determined by the contact test and rat, Rattus norvegicus Berkenhout and mouse, Mus musculus L. LD/sub 50/ values. The physicochemical parameters of water solubility, vapor pressure, and octanol/water partition coefficient for the chemicals tested in the contact test did not show a significant relationship to the E. fetida LC/sub 50/ values. These studies indicate that: (i) earthworms can be a suitable biomonitoring tool to assist in measuring the impact of organic chemicals in wastes added to soils and (ii) contact and artificial soil tests can be useful in measuring biological impacts.

  11. Fabrication of highly co2 selective metal organic framework membrane using liquid phase epitaxy approach

    KAUST Repository

    Eddaoudi, Mohamed

    2016-01-28

    Embodiments include a method of making a metal organic framework membrane comprising contacting a substrate with a solution including a metal ion and contacting the substrate with a solution including an organic ligand, sufficient to form one or more layers of a metal organic framework on a substrate. Embodiments further include a defect-free metal organic framework membrane comprising MSiF6(pyz)2, wherein M is a metal, wherein the thickness of the membrane is less than 1,000 µm, and wherein the metal organic has a growth orientation along the [110] plane relative to a substrate.

  12. Quality and Chemical Composition of Organic and Non-Organic Vetiver Oil

    Directory of Open Access Journals (Sweden)

    Asep Kadarohman

    2014-03-01

    Full Text Available Vetiver oil (Vetiveria zizanoides has been used as perfume materials, cosmetics, fragrance soaps, anti-inflammation, repellent, and insecticidal agents. Organic vetiver oil has higher economical value than non-organic vetiver oil and it has been regarded to be able to compete in the global market. Therefore, studies have been carried out using 1 hectare of land and the first generation of organic vetiver oil has produced 0.57% of yield, greater than non-organic (0.50%. The quality of organic and non-organic vetiver oil was analyzed by Indonesian Standard (SNI parameter, pesticide residue test, chemical composition by GC/MS, and the appearance of vetiver root. In general, the result of organic and non-organic vetiver oil has fulfilled the national standard; the quality of organic vetiver oil was better than non-organic one. Physically, the appearance of organic vetiver root was better than non-organic vetiver root; organic vetiver root was denser, more appealing, and did not have any black spots. The pesticide residue of organic vetiver oil was lower than non-organic vetiver oil. Based on SNI test, vetiverol (oxygen compounds in organic vetiver oil was higher than non-organic vetiver oil.

  13. Green methods for preparing highly co2 selective and h2s tolerant metal organic frameworks

    KAUST Repository

    Eddaoudi, Mohamed

    2015-12-23

    A green route for preparing a metal organic framework include mixing metal precursor with a ligand precursor to form a solvent-free mixture; adding droplets of water to the mixture; heating the mixture at a first temperature after adding the water; and isolating the metal organic framework material including the metal and the ligand.

  14. Acid-resistant organic coatings for the chemical industry: a review

    DEFF Research Database (Denmark)

    Møller, Victor Buhl; Dam-Johansen, Kim; Frankær, Sarah Maria Grundahl

    2017-01-01

    Industries that work with acidic chemicals in their processes need to make choices on how to properly contain the substances and avoid rapid corrosion of equipment. Certain organic coatings and linings can be used in such environments, either to protect vulnerable construction materials, or......, in combination with fiber reinforcement, to replace them. However, degradation mechanisms of organic coatings in acid service are not thoroughly understood and relevant quantitative investigations are scarce. This review describes the uses and limitations of acid-resistant coatings in the chemical industry......, with a comparison to alternative resistant materials based on metals or ceramics. In addition, coating degradation phenomena, caused by acid exposure, are mapped to the extent possible, and analysis methods for detecting coating degradation type and severity are listed and discussed. It is concluded that more...

  15. Changes in soil chemical and microbiological properties during 4 years of application of various organic residues.

    Science.gov (United States)

    Odlare, M; Pell, M; Svensson, K

    2008-01-01

    A 4-year field trial was established in eastern Sweden to evaluate the effects of organic waste on soil chemical and microbiological variables. A simple crop rotation with barley and oats was treated with either compost from household waste, biogas residue from household waste, anaerobically treated sewage sludge, pig manure, cow manure or mineral fertilizer. All fertilizers were amended in rates corresponding to 100kgNha(-1)year(-1). The effects of the different types of organic waste were evaluated by subjecting soil samples, taken each autumn 4 weeks after harvest, to an extensive set of soil chemical (pH, Org-C, Tot-N, Tot-P, Tot-S, P-AL, P-Olsen, K-AL, and some metals) and microbiological (B-resp, SIR, microSIR active and dormant microorganisms, PDA, microPDA, PAO, Alk-P and N-min) analyses. Results show that compost increased pH, and that compost as well as sewage sludge increased plant available phosphorus; however, the chemical analysis showed few clear trends over the 4 years and few clear relations to plant yield or soil quality. Biogas residues increased substrate induced respiration (SIR) and, compared to the untreated control amendment of biogas residues as well as compost, led to a higher proportion of active microorganisms. In addition, biogas residues increased potential ammonia oxidation rate (PAO), nitrogen mineralization capacity (N-min) as well as the specific growth rate constant of denitrifiers (microPDA). Despite rather large concentrations of heavy metals in some of the waste products, no negative effects could be seen on either chemical or microbiological soil properties. Changes in soil microbial properties appeared to occur more rapidly than most chemical properties. This suggests that soil microbial processes can function as more sensitive indicators of short-term changes in soil properties due to amendment of organic wastes.

  16. Composition and doping control for metal-organic chemical vapor deposition of InP-based double heterojunction bipolar transistor with hybrid base structure consisting of GaAsSb contact and InGaAsSb graded layers

    Science.gov (United States)

    Hoshi, Takuya; Kashio, Norihide; Sugiyama, Hiroki; Yokoyama, Haruki; Kurishima, Kenji; Ida, Minoru; Matsuzaki, Hideaki

    2017-07-01

    We report on a method for composition and doping control for metalorganic chemical vapor deposition of a double heterojunction bipolar transistor (DHBT) with a hybrid base structure consisting of a compositionally graded InGaAsSb for boosting an average electron velocity and a heavily doped thin GaAsSb for lowering the base contact resistivity. The GaAsSb contact layer can be formed by simply turning off the supply of In precursor tetramethylindium (TMIn) after the growth of the composition and doping graded InGaAsSb base. Consequently, the solid composition and hole concentration of hybrid base can be properly controlled by just modulating the supply of only TMIn and carbon tetrabromide. Secondary ion mass spectroscopy for the DHBT wafer reveals that the contents of In, Ga, and C inside the base are actually modulated from the collector side to the emitter side as expected. Transmission-line-model measurements were performed for the compositionally graded-InGaAsSb/GaAsSb hybrid base. The contact resistivity is estimated to be 5.3 Ω µm2, which is lower than half the value of a compositionally graded InGaAsSb base without the GaAsSb contact layer. The results indicate that the compositionally-graded-InGaAsSb/GaAsSb-contact hybrid base structure grown by this simple method is very advantageous for obtaining DHBTs with a very high maximum oscillation frequency.

  17. Characterization of TiO{sub 2} thin films obtained by metal-organic chemical vapour deposition; Caracterizacao de filmes finos de TiO{sub 2} obtidos por deposicao quimica em fase vapor

    Energy Technology Data Exchange (ETDEWEB)

    Carriel, Rodrigo Crociati

    2015-07-01

    Titanium dioxide (TiO{sub 2}) thin films were grown on silicon substrate (100) by MOCVD process (chemical deposition of organometallic vapor phase). The films were grown at 400, 500, 600 and 700 ° C in a conventional horizontal equipment. Titanium tetraisopropoxide was used as source of both oxygen and titanium. Nitrogen was used as carrier and purge gas. X-ray diffraction technique was used for the characterization of the crystalline structure. Scanning electron microscopy with field emission gun was used to evaluate the morphology and thickness of the films. The films grown at 400 and 500°C presented anatase phase. The film grown at 600ºC presented rutile besides anatase phase, while the film grown at 700°C showed, in addition to anatase and rutile, brookite phase. In order to evaluate the electrochemical behavior of the films cyclic voltammetry technique was used. The tests revealed that the TiO2 films formed exclusively by the anatase phase exhibit strong capacitive character. The anodic current peak is directly proportional to the square root of the scanning rate for films grown at 500ºC, suggesting that linear diffusion is the predominant mechanism of cations transport. It was observed that in the film grown during 60 minutes the Na+ ions intercalation and deintercalation easily. The films grown in the other conditions did not present the anodic current peak, although charge was accumulated in the film. (author)

  18. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-02-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm-3 was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures.

  19. Force-induced chemical reactions on the metal centre in a single metalloprotein molecule.

    Science.gov (United States)

    Zheng, Peng; Arantes, Guilherme M; Field, Martin J; Li, Hongbin

    2015-06-25

    Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions.

  20. Soil Chemical Characteristics of Organic and Conventional Agriculture

    Directory of Open Access Journals (Sweden)

    Muhammad Abdul Aziz

    2016-01-01

    Full Text Available Use of chemical fertilizers and pesticides on intensive land of both lowland and upland food crops have been shown to increase agricultural productivity significantly. Research aimed to study soil chemical characteristics and soil pesticide residues at some crops of organic and conventional farms. The research was carried out in Laboratory of Soil Chemistry, Indonesian Soil Research Institute and in Laboratory of Agrochemical Residue, Indonesian Agricultural Environment Research Institute, Bogor from February to July 2015. Soil samples at 0-10 cm depth were taken compositely from broccoli (Brassica oleracea, carrots (Daucus carota, maize (Zea mays, and tomatoes (Solanum lycopersicum farms in Bogor Regency as well as from rice field in Tasikmalaya Regency at both organic and conventional farms. Soil chemical characteristics were analyzed include: soil organic-C (Walkey and Black, total-N (Kjeldahl, potential-P (HCl 25%, available-P (Olsen, potential-K (HCl 25%, available-K (NH4OAc 1 N pH 7, CEC (NH4OAc 1 N pH 7, and pH (soil : water = 1: 5, while pesticide residues included levels of organochlorine (lindane, aldrin, heptaklor, dieldrin, DDT, endosulfan; organophosphates (diazinon, fenitrotin, metidation, paration, profenofos; and carbamates (carbofuran, MIPC, BPMC in the soil by using Gas Chromatography method. Results showed that levels of soil organic-C, total-N, potential and available-P, potential and available-K, CEC, pH at organic farms were higher than those at conventional farms. Some pesticide residues compound (organochlorines, organophosphates, and carbamates were detected at conventional farm, while those at organic farm were not detected (trace.

  1. Metal inhibition on the reactivity of manganese dioxide toward organic contaminant oxidation in relation to metal adsorption and ionic potential.

    Science.gov (United States)

    Jiang, Jing; Wang, Zhuopu; Chen, Yang; He, Anfei; Li, Jianliang; Sheng, G Daniel

    2017-03-01

    Coexisting metal ions may significantly inhibit the oxidative reactivity of manganese oxides toward organic contaminants in metal-organic multi-pollutant waters. While the metal inhibition on the oxidation of organic contaminants by manganese oxides has previously been reported, the extent of the inhibition in relation to metal properties has not been established. Six alkali, alkaline, and transition metals, as well as two testing metals were evaluated for their abilities to inhibit the reactivity of birnessite. Regardless of the pathways of phenol and diuron oxidation (polymerization vs. breakdown), the extent of metal inhibition depended mainly on the metal itself and its concentration. The observed metal inhibition efficiency followed the order of Mn 2+  > Co 2+  > Cu 2+  > Al 3+  > Mg 2+  > K + , consistent with metal adsorption on birnessite. The first-order organic oxidation rate constant (k obs ) was linearly negatively correlated with metal adsorption (q e ) on birnessite. These observations demonstrated that the metal inhibition efficiency was determined by metal adsorption on birnessite. The slopes of the k obs -q e varied among metals and followed the order of K +  > Ca 2+  > Mg 2+  > Mn 2+  > Cd 2+  > Co 2+  > Cu 2+  > Al 3+ . These slopes defined intrinsic inhibitory abilities of metals. As metals were adsorbed hydrated on birnessite, the intrinsic inhibitory ability was significantly linearly correlated with ionic potentials of metals, leading to a single straight line. Metals with multiple d electrons in the outermost orbit with polarizing energy that promotes hydrolysis sat slightly below the line, and vice versa. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Gas uptake and chemical aging of semisolid organic aerosol particles.

    Science.gov (United States)

    Shiraiwa, Manabu; Ammann, Markus; Koop, Thomas; Pöschl, Ulrich

    2011-07-05

    Organic substances can adopt an amorphous solid or semisolid state, influencing the rate of heterogeneous reactions and multiphase processes in atmospheric aerosols. Here we demonstrate how molecular diffusion in the condensed phase affects the gas uptake and chemical transformation of semisolid organic particles. Flow tube experiments show that the ozone uptake and oxidative aging of amorphous protein is kinetically limited by bulk diffusion. The reactive gas uptake exhibits a pronounced increase with relative humidity, which can be explained by a decrease of viscosity and increase of diffusivity due to hygroscopic water uptake transforming the amorphous organic matrix from a glassy to a semisolid state (moisture-induced phase transition). The reaction rate depends on the condensed phase diffusion coefficients of both the oxidant and the organic reactant molecules, which can be described by a kinetic multilayer flux model but not by the traditional resistor model approach of multiphase chemistry. The chemical lifetime of reactive compounds in atmospheric particles can increase from seconds to days as the rate of diffusion in semisolid phases can decrease by multiple orders of magnitude in response to low temperature or low relative humidity. The findings demonstrate that the occurrence and properties of amorphous semisolid phases challenge traditional views and require advanced formalisms for the description of organic particle formation and transformation in atmospheric models of aerosol effects on air quality, public health, and climate.

  3. The energetic and chemical signatures of persistent soil organic matter

    DEFF Research Database (Denmark)

    Barré, Pierre; Plante, Alain F.; Cecillon, Lauric

    2016-01-01

    A large fraction of soil organic matter (OM) resists decomposition over decades to centuries as indicated by long radiocarbon residence times, but the mechanisms responsible for the long-term (multi-decadal) persistence are debated. The current lack of mechanistic understanding limits our ability...... chemical composition. From an energetic point of view, thermal analyses revealed that combustion of persistent OM occurred at higher temperature and provided less energy than combustion of more labile OM. In terms of chemical composition, persistent OM was H-depleted compared to OM present at the start...... of bare fallow, but spectroscopic analyses of OM functional groups did not reflect a consistent chemical composition of OM across sites, nor substantial modifications with bare fallow duration. The low energy content of persistent OM may be attributed to a combination of reduced content of energetic C...

  4. Algal growth inhibition test results of 425 organic chemical substances

    DEFF Research Database (Denmark)

    Kusk, Kresten Ole; Christensen, Anne Munch; Nyholm, Niels

    2018-01-01

    values were corrected accordingly. The model helped to identify substances, where the calculated water concentration was too uncertain. Substances covering a wide range of physical-chemical properties and different modes of action were tested. Median effect concentrations (EC50) lower than 1000 mg/L were......The toxicity towards the algal species Pseudokirchneriella subcapitata of 425 organic chemical substances was tested in a growth inhibition test. Precautions were taken to prevent loss of the compounds from the water phase and the test system (closed test system, low biomass, shorter test duration......, silanized glass) and to keep pH constant by applying a higher alkalinity. Chemical phase distribution was modelled taking ionization, volatilisation, and adsorption to glass and biomass into consideration. If the modelled water concentration was below 90% of the nominal concentration the calculated EC...

  5. Temperature influence on chemical toxicity to aquatic organisms

    International Nuclear Information System (INIS)

    Cairns, J. Jr.; Heath, A.G.; Parker, B.C.

    1975-01-01

    The literature on the effects of temperature on chemical toxicity to aquatic animals and microorganisms is reviewed. Microbial photosynthesis and respiration is briefly discussed. It is concluded that there is a paucity of information on the inter-relations of temperature and toxicants to algae, bacteria, and protozoa and that standards based on the in situ response of indigenous organisms to specific discharge areas should be developed

  6. PROCESS CONTROL IN THE EDUCATION OF ORGANIC CHEMICAL TECHNOLOGY

    OpenAIRE

    Csontos, lstván; Department of Organic Chemical Technology, Budapest University of Technology and Economics; Marosi, György; Department of Organic Chemical Technology, Budapest University of Technology and Economics; Faigl, Ferenc; Department of Organic Chemical Technology, Budapest University of Technology and Economics

    2013-01-01

    Laboratory practices for demonstrating the importance of advanced process control methods in the organic chemical technologies have been elaborated. It required the development of a system tha tintegrates the advantages of a reaction calorimeter and a model system of industrial controlled reactors. The hardware and software configuration support the transfer of elaborated control programs of reactions from laboratory level to the industrial technology. General control algorithms of diazotizat...

  7. Noise-Induced Hearing Loss in Korean Workers: Co-Exposure to Organic Solvents and Heavy Metals in Nationwide Industries

    Science.gov (United States)

    Choi, Yoon-Hyeong; Kim, KyooSang

    2014-01-01

    Background Noise exposure is a well-known contributor to work-related hearing loss. Recent biological evidence suggests that exposure to ototoxic chemicals such as organic solvents and heavy metals may be additional contributors to hearing loss. However, in industrial settings, it is difficult to determine the risks of hearing loss due to these chemicals in workplaces accompanied by excessive noise exposure. A few studies suggest that the effect of noise may be enhanced by ototoxic chemicals. Therefore, this study investigated whether co-exposure to organic solvents and/or heavy metals in the workplace modifies the risk of noise exposure on hearing loss in a background of excessive noise. Methods We examined 30,072 workers nationwide in a wide range of industries from the Korea National Occupational Health Surveillance 2009. Data on industry-based exposure (e.g., occupational noise, heavy metals, and organic solvents) and subject-specific health outcomes (e.g., audiometric examination) were collected. Noise was measured as the daily 8-h time-weighted average level. Air conduction hearing thresholds were measured from 0.5 to 6 kHz, and pure-tone averages (PTA) (i.e., means of 2, 3, and 4 kHz) were computed. Results In the multivariate linear model, PTA increment with occupational noise were 1.64-fold and 2.15-fold higher in individuals exposed to heavy metals and organic solvents than in unexposed individuals, respectively. Conclusion This study provides nationwide evidence that co-exposure to heavy metals and/or organic solvents may exacerbate the effect of noise exposure on hearing loss in workplaces. These findings suggest that workers in industries dealing with heavy metals or organic solvents are susceptible to such risks. PMID:24870407

  8. Noise-induced hearing loss in Korean workers: co-exposure to organic solvents and heavy metals in nationwide industries.

    Directory of Open Access Journals (Sweden)

    Yoon-Hyeong Choi

    Full Text Available BACKGROUND: Noise exposure is a well-known contributor to work-related hearing loss. Recent biological evidence suggests that exposure to ototoxic chemicals such as organic solvents and heavy metals may be additional contributors to hearing loss. However, in industrial settings, it is difficult to determine the risks of hearing loss due to these chemicals in workplaces accompanied by excessive noise exposure. A few studies suggest that the effect of noise may be enhanced by ototoxic chemicals. Therefore, this study investigated whether co-exposure to organic solvents and/or heavy metals in the workplace modifies the risk of noise exposure on hearing loss in a background of excessive noise. METHODS: We examined 30,072 workers nationwide in a wide range of industries from the Korea National Occupational Health Surveillance 2009. Data on industry-based exposure (e.g., occupational noise, heavy metals, and organic solvents and subject-specific health outcomes (e.g., audiometric examination were collected. Noise was measured as the daily 8-h time-weighted average level. Air conduction hearing thresholds were measured from 0.5 to 6 kHz, and pure-tone averages (PTA (i.e., means of 2, 3, and 4 kHz were computed. RESULTS: In the multivariate linear model, PTA increment with occupational noise were 1.64-fold and 2.15-fold higher in individuals exposed to heavy metals and organic solvents than in unexposed individuals, respectively. CONCLUSION: This study provides nationwide evidence that co-exposure to heavy metals and/or organic solvents may exacerbate the effect of noise exposure on hearing loss in workplaces. These findings suggest that workers in industries dealing with heavy metals or organic solvents are susceptible to such risks.

  9. Noise-induced hearing loss in Korean workers: co-exposure to organic solvents and heavy metals in nationwide industries.

    Science.gov (United States)

    Choi, Yoon-Hyeong; Kim, KyooSang

    2014-01-01

    Noise exposure is a well-known contributor to work-related hearing loss. Recent biological evidence suggests that exposure to ototoxic chemicals such as organic solvents and heavy metals may be additional contributors to hearing loss. However, in industrial settings, it is difficult to determine the risks of hearing loss due to these chemicals in workplaces accompanied by excessive noise exposure. A few studies suggest that the effect of noise may be enhanced by ototoxic chemicals. Therefore, this study investigated whether co-exposure to organic solvents and/or heavy metals in the workplace modifies the risk of noise exposure on hearing loss in a background of excessive noise. We examined 30,072 workers nationwide in a wide range of industries from the Korea National Occupational Health Surveillance 2009. Data on industry-based exposure (e.g., occupational noise, heavy metals, and organic solvents) and subject-specific health outcomes (e.g., audiometric examination) were collected. Noise was measured as the daily 8-h time-weighted average level. Air conduction hearing thresholds were measured from 0.5 to 6 kHz, and pure-tone averages (PTA) (i.e., means of 2, 3, and 4 kHz) were computed. In the multivariate linear model, PTA increment with occupational noise were 1.64-fold and 2.15-fold higher in individuals exposed to heavy metals and organic solvents than in unexposed individuals, respectively. This study provides nationwide evidence that co-exposure to heavy metals and/or organic solvents may exacerbate the effect of noise exposure on hearing loss in workplaces. These findings suggest that workers in industries dealing with heavy metals or organic solvents are susceptible to such risks.

  10. Availability of heavy metals in contaminated soil evidenced by chemical extractants

    Directory of Open Access Journals (Sweden)

    Maria Ligia de Souza Silva

    2012-06-01

    Full Text Available Heavy metals have been accumulating in Brazilian soils, due to natural processes, such as atmospheric deposition, or human industrial activities. For certain heavy metals, when in high concentrations in the soil, there is no specific extractant to determine the availability of these elements in the soil. The objective of the present study was to evaluate the availability of Cd, Cu, Fe, Mn, Pb and Zn for rice and soybeans, using different chemical extractants. In this study we used seven soil samples with different levels of contamination, in completely randomized experimental design with four replications. We determined the available concentrations of Cd, Cu, Fe, Mn, Pb and Zn extracted by Mehlich-1, HCl 0.1 mol L-1, DTPA, and organic acid extractants and the contents in rice and soybeans, which extracts were analyzed by ICP-OES. It was observed that Mehlich-1, HCl 0.1 mol L-1 and DTPA extractants were effective to assess the availability of Cd, Cu, Pb and Zn for rice and soybeans. However, the same was not observed for the organic acid extractant.

  11. Evaluation of physical, chemical and heavy metal concentration of food waste composting

    Directory of Open Access Journals (Sweden)

    Abdul Kadir Aeslina

    2017-01-01

    Full Text Available In this study, food waste composting with rice husk and coconut fibre as compost medium were carried out. Two types of different fermentation liquids were prepared which were fermented liquid (banana peel and fermented liquid from fermented soybeans. During the composting process, a compost samples for a twenty week duration at an interval time of two weeks. Among the physico-chemical parameters that were tested were temperature, moisture content, pH value, Total Nitrogen, Total Phosphorous, Potassium and Total Organic Carbon and Carbon Nitrogen ratio. Heavy metals such as copper, cadmium, lead, nickel and arsenic were observed and analysed. From this study, it was found that, the temperature increased during the thermophilic phase while there was gradually increase of Total Nitrogen, Total Phosphorous and Potassium from the beginning till the end of the composting process. It was also found that the total organic carbon (TOC and the carbon nitrogen ratio decreased significantly during the decomposition process. Traces amounts of heavy metals were also detected and remains below the standard Malaysian Environmental regulations. It was concluded that, the composting process was faster with processed food waste followed by combination of processed food waste and raw. Raw food waste were demonstrated the lowest degradation rate.

  12. Chemical exergy assessment of organic matter in a water flow

    International Nuclear Information System (INIS)

    Martinez, Amaya; Uche, Javier

    2010-01-01

    In recent years, exergy analysis has been successfully applied to natural resources assessment. The consumption of any natural resource is unavoidably joined to dispersion and degradation. Therefore, exergy analysis can be applied to study the depletion of natural resources and, particularly, to water resources. Different studies range from global fresh water resources evaluation to specific water bodies' detailed analysis. Physical Hydronomics is a new approach based on the specific application of Thermodynamics to physically characterize the state of a river and to help in the Governance of water bodies. The core task in the methodology is the construction of the exergy profiles of the river and it requires the calculation of the different specific exergy components in the water body: potential, thermal, mechanical, kinetic and chemical exergy. This paper is focused on the exergy assessment for the organic chemical matter present in water bodies. Different parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD) or total organic carbon (TOC), among others, can be used as raw data for the calculation. Starting from available sampling data, previous approaches are analyzed, completed and compared. The well-known and most simple average molecule representing the organic matter in the river (CH 2 O) is proposed. Results show that, considering surface waters, TOC parameter is the most convenient one, but also that the BOD and COD can be reasonably useful.

  13. Organic derivatives of lanthanides containing metal in cycle

    International Nuclear Information System (INIS)

    Syutkina, O.P.; Rybakova, L.F.; Egorova, E.N.; Sigalov, A.B.; Beletskaya, I.P.

    1983-01-01

    The reaction of 2.2'-dilithium biphenyl with LnBr 3 (Ln=Pr, Sm, Gd, Ho, Yb here bromium atoms are comparatively easily replaced. Previously unknown organic derivatives of lanthanides containing metal in the cycle are obtained. It is established that a successful extraction of the compound requires reaction conditions, such as the use of ether as a solvent with the followinq addition of TGP, the order of addition of reagents. Compounds are extracted in the form of solvates containing TGP melecules. The complexes prepared are coloured, depending on the metal, beige (Pr, Sm) brown (Gd, Yb) and red-brown (Ho). They dissolve readily in TGP moderately in benzen toluene, CCl 4 . When stored their solubility in benzene and CCl 4 decreases considerably, and after 3-2 days, they are practically insoluhle. The compounds prepared are characterized by the elementary analysis, IR and PMR spectra

  14. Xenon Recovery at Room Temperature using Metal-Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Elsaidi, Sameh K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Ongari, Daniele [Laboratory of Molecular Simulation, Institut des Sciences et Ingeénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l' Industrie 17 1951 Sion Valais Switzerland; Xu, Wenqian [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Mohamed, Mona H. [Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Haranczyk, Maciej [IMDEA Materials Institute, c/Eric Kandel 2 28906 Getafe, Madrid Spain; Thallapally, Praveen K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2017-07-24

    Xenon is known to be a very efficient anesthetic gas but its cost prohibits the wider use in medical industry and other potential applications. It has been shown that Xe recovery and recycle from anesthetic gas mixture can significantly reduce its cost as anesthetic. The current technology uses series of adsorbent columns followed by low temperature distillation to recover Xe, which is expensive to use in medical facilities. Herein, we propose much efficient and simpler system to recover and recycle Xe from simulant exhale anesthetic gas mixture at room temperature using metal organic frameworks. Among the MOFs tested, PCN-12 exhibits unprecedented performance with high Xe capacity, Xe/N2 and Xe/O2 selectivity at room temperature. The in-situ synchrotron measurements suggest the Xe is occupied in the small pockets of PCN-12 compared to unsaturated metal centers (UMCs). Computational modeling of adsorption further supports our experimental observation of Xe binding sites in PCN-12.

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

    Science.gov (United States)

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

    2016-04-19

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

  16. 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.

  17. Interaction of Hydroxyproline with Bivalent Metal Ions in Chemical ...

    African Journals Online (AJOL)

    NICO

    The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were ... metal ions have several significant applications in biological systems.3–20 Beryllium is one ... 1 filter paper for chromatography was used for the purpose of electrophoresis. An Elico ...

  18. Encoding of Fundamental Chemical Entities of Organic Reactivity Interest using chemical ontology and XML.

    Science.gov (United States)

    Durairaj, Vijayasarathi; Punnaivanam, Sankar

    2015-09-01

    Fundamental chemical entities are identified in the context of organic reactivity and classified as appropriate concept classes namely ElectronEntity, AtomEntity, AtomGroupEntity, FunctionalGroupEntity and MolecularEntity. The entity classes and their subclasses are organized into a chemical ontology named "ChemEnt" for the purpose of assertion, restriction and modification of properties through entity relations. Individual instances of entity classes are defined and encoded as a library of chemical entities in XML. The instances of entity classes are distinguished with a unique notation and identification values in order to map them with the ontology definitions. A model GUI named Entity Table is created to view graphical representations of all the entity instances. The detection of chemical entities in chemical structures is achieved through suitable algorithms. The possibility of asserting properties to the entities at different levels and the mechanism of property flow within the hierarchical entity levels is outlined. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. High-Throughput Molecular Simulations of Metal Organic Frameworks for CO2 Separation: Opportunities and Challenges

    Directory of Open Access Journals (Sweden)

    Ilknur Erucar

    2018-02-01

    Full Text Available Metal organic frameworks (MOFs have emerged as great alternatives to traditional nanoporous materials for CO2 separation applications. MOFs are porous materials that are formed by self-assembly of transition metals and organic ligands. The most important advantage of MOFs over well-known porous materials is the possibility to generate multiple materials with varying structural properties and chemical functionalities by changing the combination of metal centers and organic linkers during the synthesis. This leads to a large diversity of materials with various pore sizes and shapes that can be efficiently used for CO2 separations. Since the number of synthesized MOFs has already reached to several thousand, experimental investigation of each MOF at the lab-scale is not practical. High-throughput computational screening of MOFs is a great opportunity to identify the best materials for CO2 separation and to gain molecular-level insights into the structure–performance relationships. This type of knowledge can be used to design new materials with the desired structural features that can lead to extraordinarily high CO2 selectivities. In this mini-review, we focused on developments in high-throughput molecular simulations of MOFs for CO2 separations. After reviewing the current studies on this topic, we discussed the opportunities and challenges in the field and addressed the potential future developments.

  20. Metal-organic aerogel as a coating for solid-phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Saraji, Mohammad, E-mail: saraji@cc.iut.ac.ir; Shahvar, Ali

    2017-06-22

    An iron-based metal-organic aerogel was synthesized using metal-organic framework nanoparticles and applied as a fiber coating for solid-phase microextraction (SPME). Chemical, thermal and morphological characteristics of the material were investigated. Headspace SPME followed by gas chromatography-electron capture detection was used for the determination of chlorobenzenes in the environmental samples. The key experimental factors affecting the extraction efficiency of the analytes, such as ionic strength, extraction and desorption temperature, and extraction time were investigated and optimized. The applicability of the coating for the extraction of chlorobenzenes from the environmental samples including river and tap water, sludge, and coastal soil was evaluated. The detection limits were in the range of 0.1–60 ng L{sup −1}. The relative standard deviations were between 2.0 and 5.0%. The extraction recovery of the analytes was in the range of 88–100%. Compared to the commercial PDMS fiber, the present fiber showed better extraction efficiency. - Highlights: • Metal-organic aerogel was synthesized and used as a novel fiber coating for SPME. • The new coating material showed high surface area and good thermal stability. • GC-ECD was used for determination of chlorobenzenes in environmental samples. • The method showed fast extraction and better efficiency than PDMS commercial fiber.

  1. Formation of self-organized nanoporous anodic oxide from metallic gallium.

    Science.gov (United States)

    Pandey, Bipin; Thapa, Prem S; Higgins, Daniel A; Ito, Takashi

    2012-09-25

    This paper reports the formation of self-organized nanoporous gallium oxide by anodization of solid gallium metal. Because of its low melting point (ca. 30 °C), metallic gallium can be shaped into flexible structures, permitting the fabrication of nanoporous anodic oxide monoliths within confined spaces like the inside of a microchannel. Here, solid gallium films prepared on planar substrates were employed to investigate the effects of anodization voltage (1, 5, 10, 15 V) and H(2)SO(4) concentration (1, 2, 4, 6 M) on anodic oxide morphology. Self-organized nanopores aligned perpendicular to the film surface were obtained upon anodization of gallium films in ice-cooled 4 and 6 M aqueous H(2)SO(4) at 10 and 15 V. Nanopore formation could be recognized by an increase in anodic current after a current decrease reflecting barrier oxide formation. The average pore diameter was in the range of 18-40 nm with a narrow diameter distribution (relative standard deviation ca. 10-20%), and was larger at lower H(2)SO(4) concentration and higher applied voltage. The maximum thickness of nanoporous anodic oxide was ca. 2 μm. In addition, anodic formation of self-organized nanopores was demonstrated for a solid gallium monolith incorporated at the end of a glass capillary. Nanoporous anodic oxide monoliths formed from a fusible metal will lead to future development of unique devices for chemical sensing and catalysis.

  2. Chemical characterization of agricultural supplies applied to organic tomato cultivation

    International Nuclear Information System (INIS)

    Martins, T.C.G.; Nadai Fernandes de, E.A.; Ferrari, A.A.; Tagliaferro, F.S.; Bacchi, M.A.

    2008-01-01

    The agricultural supplies used in the organic system to control pests and diseases as well as to fertilize soil are claimed to be beneficial to plants and innocuous to human health and to the environment. The chemical composition of six agricultural supplies commonly used in the organic tomato culture, was evaluated by instrumental neutron activation analysis (INAA). Results were compared to the maximum limits established by the Environment Control Agency of the S?o Paulo State (CETESB) and the Guidelines for Organic Quality Standard of Instituto Biodinamico (IBD). Concentrations above reference values were found for Co, Cr and Zn in compost, Cr and Zn in cattle manure and Zn in rice bran. (author)

  3. Leakage radiation spectroscopy of organic/dielectric/metal systems

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Kawalec, Tomasz; Kostiučenko, Oksana

    2014-01-01

    side of a hemisphere fused silica prism with an index matching liquid was illuminated under normal incidence by a He-Cd 325 nm laser. Two orthogonal linear polarizations were used both parallel and perpendicular to the detection plane. Spectrally resolved leakage radiation was observed on the opposite...... excitons and surface plasmon polaritons (SPPs) of the metal/dielectric boundary. The presence of the SiO2 layer considerably changes the dispersion curve in comparison to the one of the Ag/p-6P/air system. However, the Ag/SiO2/p-6P/air stack forms a stable structure allowing construction of organic...

  4. On-Surface Synthesis and Reactivity of Functional Organic and Metal-Organic Adsorbates at Metal Surfaces by Vibrational Spectroscopy

    Science.gov (United States)

    Williams, Christopher Glen

    catalysts. We accomplished this by metal coordination to redox non-innocent dipyridyl-tetrazine ligands. We utilize HREELS to observe a surface confined redox process of dipyridyl-tetrazine with V, Fe, Ag, and Pt. With the formation of the V-dipyridyl-tetrazine species, we are able to see that oxygen exposures to the surface results in a more selective vanadyl species formation as opposed to the multiple binding conformations observed with metallic vanadium nanoparticles. This thesis also reveals that the metal substrate used does not play a passive role with the metal-organic complex. Instead, we are the first to characterize a replacement of the coordinating metal species with atoms from the Ag(111) substrate. This replacement results in the redox reaction between the coordinating metal species and the substrate metal.

  5. Bond lengths in organic and metal-organic compounds revisited: X-H bond lengths from neutron diffraction data.

    Science.gov (United States)

    Allen, Frank H; Bruno, Ian J

    2010-06-01

    The number of structures in the Cambridge Structural Database (CSD) has increased by an order of magnitude since the preparation of two major compilations of standard bond lengths in mid-1985. It is now of interest to examine whether this huge increase in data availability has implications for the mean bond-length values published in the late 1980s. Those compilations reported mean X-H bond lengths derived from rather sparse information and for rather few chemical environments. During the intervening years, the number of neutron studies has also increased, although only by a factor of around 2.25, permitting a new analysis of X-H bond-length distributions for (a) organic X = C, N, O, B, and (b) a variety of terminal and homometallic bridging transition metal hydrides. New mean values are reported here and are compared with earlier results. These new overall means are also complemented by an analysis of X-H distances at lower temperatures (T chemical environments for which statistically acceptable mean X-H bond lengths can be obtained, although values from individual structures are also collated to further extend the chemical range of this compilation. Updated default 'neutron-normalization' distances for use in hydrogen-bond and deformation-density studies are also proposed for C-H, N-H and O-H, and the low-temperature analysis provides specific values for certain chemical environments and hybridization states of X.

  6. Biosensor and chemical sensor probes for calcium and other metal ions

    Science.gov (United States)

    Vo-Dinh, Tuan; Viallet, Pierre

    1996-01-01

    The present invention relates to chemical sensor and biosensor probes for measuring low concentration of metals and metal ions in complex samples such as biological fluids, living cells, and environmental samples. More particularly the present invention relates to a gel-based Indo-1 and Fura-2 chemical sensor probes for the measurement of low concentrations of calcium, cadmium, magnesium and the like. Also disclosed is a detector device using the sensors of the present invention.

  7. Insight into the construction of metal-organic polyhedra: Metal-organic cubes as a case study

    KAUST Repository

    Al Kordi, Mohamed

    2011-01-01

    Systematic studies were conducted to gain a better understanding of the metal-organic cubes (MOCs) directed assembly and their crystallization under predetermined reaction conditions, i.e. charge and size of metal ions, solvent type, counter anions, pH, and temperature. Four novel metal-organic materials are constructed via solvothermal reactions of different metal ions and 2,2′-(1H-imidazole-4,5-diyl)di-1,4,5,6-tetrahydropyrimidine, namely [Co8(C11N6H15)12]Cl 12·4H2O (1), [Ni4(C11N 6H15)4](NO3)4· 4DMF (2), {Cd(C11N6H15)(NO3) ·DMF}n (3), and [In8(C11N 6H15)12](NO3)12· 4H2O (4). In addition, syntheses and crystal structures for compounds 1(a-f), constructed under deliberately modified reaction conditions of 1, are reported. In compounds 1(a-f), the CoIII-based cationic MOCs crystallize in various packing arrangements in the presence of different counter-ions. Discrete MOCs retain their structural integrity, when crystalline solid was dissolved in water, under various pH (2.03-8.07) and temperatures (298-333 K), as confirmed by solution NMR studies. The assembly of the discrete MOC, from its basic molecular building blocks under mild reaction conditions, is demonstrated and monitored through solution NMR and UV-vis studies. © The Royal Society of Chemistry 2011.

  8. Sulfate Reduction Remediation of a Metals Plume Through Organic Injection

    International Nuclear Information System (INIS)

    Phifer, M.A.

    2003-01-01

    Laboratory testing and a field-scale demonstration for the sulfate reduction remediation of an acidic/metals/sulfate groundwater plume at the Savannah River Site has been conducted. The laboratory testing consisted of the use of anaerobic microcosms to test the viability of three organic substrates to promote microbially mediated sulfate reduction. Based upon the laboratory testing, soybean oil and sodium lactate were selected for injection during the subsequent field-scale demonstration. The field-scale demonstration is currently ongoing. Approximately 825 gallons (3,123 L) of soybean oil and 225 gallons (852 L) of 60 percent sodium lactate have been injected into an existing well system within the plume. Since the injections, sulfate concentrations in the injection zone have significantly decreased, sulfate-reducing bacteria concentrations have significantly increased, the pH has increased, the Eh has decreased, and the concentrations of many metals have decreased. Microbially mediated sulfate reduction has been successfully promoted for the remediation of the acidic/metals/sulfate plume by the injection of soybean oil and sodium lactate within the plume

  9. Metal-organic frameworks for adsorption and separation of noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Greathouse, Jeffery A.; Staiger, Chad

    2017-05-30

    A method including exposing a gas mixture comprising a noble gas to a metal organic framework (MOF), including an organic electron donor and an adsorbent bed operable to adsorb a noble gas from a mixture of gases, the adsorbent bed including a metal organic framework (MOF) including an organic electron donor.

  10. Estimating toxicity of organic chemicals to activated-sludge microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Sun, B.; Nirmalakhandan, N.; Hall, E.; Wang, X.H.; Prakash, J.; Maynes, R. (New Mexico State Univ., Las Cruces, NM (United States))

    Inhibition of respiration rates (IC[sub 50]) of activated-sludge (AS) microorganisms and a commercial surrogate culture, Polytox, were measured using the respirometric technique for 50 organic chemicals. The correlation between the IC[sub 50] values for the two cultures was found to be highly significant with r[sup 2] = 0.928, the Polytox cultures being more sensitive than AS cultures. Using AS experimental inhibition data for a training set of 40 chemicals, a single-variable quantitative structure activity relationship (QSAR) model was developed to estimate IC[sub 50] for AS. When this QSAR model was tested on a testing set of 10 ''new'' chemicals, the predicted IC[sub 50] values agreed well with the experimentally measured values, with r[sup 2] = 0.844 at p = 0.0002. Inhibition data reported in the literature for 32 additional chemicals were also compared with predictions made by the QSAR model, and the agreement was satisfactory, with an overall r[sup 2] of 0.798, at p = 0.0001.

  11. Facile preparation of hierarchically porous carbons from metal-organic gels and their application in energy storage.

    Science.gov (United States)

    Xia, Wei; Qiu, Bin; Xia, Dingguo; Zou, Ruqiang

    2013-01-01

    Porous carbon materials have numerous applications due to their thermal and chemical stability, high surface area and low densities. However, conventional preparing porous carbon through zeolite or silica templates casting has been criticized by the costly and/or toxic procedure. Creating three-dimensional (3D) carbon products is another challenge. Here, we report a facile way to prepare porous carbons from metal-organic gel (MOG) template, an extended metal-organic framework (MOF) structure. We surprisingly found that the carbon products inherit the highly porous nature of MOF and combine with gel's integrated character, which results in hierarchical porous architectures with ultrahigh surface areas and quite large pore volumes. They exhibit considerable hydrogen uptake and excellent electrochemical performance as cathode material for lithium-sulfur battery. This work provides a general method to fast and clean synthesis of porous carbon materials and opens new avenues for the application of metal-organic gel in energy storage.

  12. Facile preparation of hierarchically porous carbons from metal-organic gels and their application in energy storage

    Science.gov (United States)

    Xia, Wei; Qiu, Bin; Xia, Dingguo; Zou, Ruqiang

    2013-06-01

    Porous carbon materials have numerous applications due to their thermal and chemical stability, high surface area and low densities. However, conventional preparing porous carbon through zeolite or silica templates casting has been criticized by the costly and/or toxic procedure. Creating three-dimensional (3D) carbon products is another challenge. Here, we report a facile way to prepare porous carbons from metal-organic gel (MOG) template, an extended metal-organic framework (MOF) structure. We surprisingly found that the carbon products inherit the highly porous nature of MOF and combine with gel's integrated character, which results in hierarchical porous architectures with ultrahigh surface areas and quite large pore volumes. They exhibit considerable hydrogen uptake and excellent electrochemical performance as cathode material for lithium-sulfur battery. This work provides a general method to fast and clean synthesis of porous carbon materials and opens new avenues for the application of metal-organic gel in energy storage.

  13. Effect of metals on Candida albicans growth in the presence of chemical chelators and human abscess fluid.

    Science.gov (United States)

    Sohnle, P G; Hahn, B L; Karmarkar, R

    2001-04-01

    Calprotectin is a calcium- and zinc-binding protein that is present in abscess fluid supernatants and appears to inhibit microbial growth through competition for zinc. In the present study, growth inhibition by chemical chelators was compared with that produced by human abscess fluid to determine whether other chelators, perhaps with different metal specificities, would have the same or different patterns of metal reversibility as abscess fluid. Zinc was found to be more potent than the other metals tested in reversing C. albicans growth inhibition by human abscess fluid and three chemical chelators, even though in some cases the stability constants of certain of these chelators were higher for other metals. For example, in the presence of the chelator diethylenetriaminopentaacetic acid, zinc stimulated Candida growth at a 10-fold lower concentration than did iron, even though this chelator has a stability constant for iron that is almost 10(10) higher than that for zinc. These results suggest that the zinc specificity of calprotectin's C. albicans growth inhibition can best be explained by the marked sensitivity of this organism to zinc deprivation rather than by selective binding of this metal by the protein.

  14. Microwave separation of organic chemicals from mixed hazardous waste

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, A.A.; Albano, R.K.

    1992-08-01

    The feasibility of utilizing the differential heating characteristics of microwave energy (MW) to aid in the chemical extraction and separation process of hazardous organic compounds from mixed hazardous waste, was studied at the INEL. The long-term objective of this work was to identify a practical method of separating or enhancing the separation process of organic hazardous waste components from mixed waste using microwave (MW) frequency radiation. Methods using MW energy for calcination, solidification, and drying of radioactive waste from nuclear facilities is becoming more attractive. In order to study the effectiveness of MW heating, samples of several organic chemicals simulating those which may be found at the Radioactive Waste Management Complex at the INEL were exposed to MW energy. Vapor collection and analysis was performed as a function of time, signal frequency, and MW power throughout the process. Signal frequencies ranging from 900 MHz t 8000 MHz were used. Although the signal frequency bandwidth of the selectivity was quite broad, for the material tested an indication of the frequency dependence in the selectivity of MW heating was given. Greater efficiency in terms of energy used and time required was observed. The relatively large electromagnetic field intensities generated at the resonant frequencies which were supported by the cavity sample holder demonstrated the use of cavity resonance to aid in the process of differential heating.

  15. Microwave separation of organic chemicals from mixed hazardous waste

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, A.A.; Albano, R.K.

    1992-01-01

    The feasibility of utilizing the differential heating characteristics of microwave energy (MW) to aid in the chemical extraction and separation process of hazardous organic compounds from mixed hazardous waste, was studied at the INEL. The long-term objective of this work was to identify a practical method of separating or enhancing the separation process of organic hazardous waste components from mixed waste using microwave (MW) frequency radiation. Methods using MW energy for calcination, solidification, and drying of radioactive waste from nuclear facilities is becoming more attractive. In order to study the effectiveness of MW heating, samples of several organic chemicals simulating those which may be found at the Radioactive Waste Management Complex at the INEL were exposed to MW energy. Vapor collection and analysis was performed as a function of time, signal frequency, and MW power throughout the process. Signal frequencies ranging from 900 MHz t 8000 MHz were used. Although the signal frequency bandwidth of the selectivity was quite broad, for the material tested an indication of the frequency dependence in the selectivity of MW heating was given. Greater efficiency in terms of energy used and time required was observed. The relatively large electromagnetic field intensities generated at the resonant frequencies which were supported by the cavity sample holder demonstrated the use of cavity resonance to aid in the process of differential heating.

  16. Microwave separation of organic chemicals from mixed hazardous waste

    International Nuclear Information System (INIS)

    Anderson, A.A.; Albano, R.K.

    1992-01-01

    The feasibility of utilizing the differential heating characteristics of microwave energy (MW) to aid in the chemical extraction and separation process of hazardous organic compounds from mixed hazardous waste, was studied at the INEL. The long-term objective of this work was to identify a practical method of separating or enhancing the separation process of organic hazardous waste components from mixed waste using microwave (MW) frequency radiation. Methods using MW energy for calcination, solidification, and drying of radioactive waste from nuclear facilities is becoming more attractive. In order to study the effectiveness of MW heating, samples of several organic chemicals simulating those which may be found at the Radioactive Waste Management Complex at the INEL were exposed to MW energy. Vapor collection and analysis was performed as a function of time, signal frequency, and MW power throughout the process. Signal frequencies ranging from 900 MHz t 8000 MHz were used. Although the signal frequency bandwidth of the selectivity was quite broad, for the material tested an indication of the frequency dependence in the selectivity of MW heating was given. Greater efficiency in terms of energy used and time required was observed. The relatively large electromagnetic field intensities generated at the resonant frequencies which were supported by the cavity sample holder demonstrated the use of cavity resonance to aid in the process of differential heating

  17. Structural versatility of Metal-organic frameworks: Synthesis and Characterization

    KAUST Repository

    Alsadun, Norah S.

    2017-05-01

    Metal-Organic Frameworks (MOFs), an emerging class of porous crystalline materials, have shown promising properties for diverse applications such as catalysis, gas storage and separation. The high degree of tunability of MOFs vs other solid materials enable the assembly of advanced materials with fascinating properties for specific applications. Nevertheless, the precise control in the construction of MOFs at the molecular level remains challenging. Particularly, the formation of pre-targeted multi-nuclear Molecular Building Block (MBB) precursors to unveil materials with targeted structural characteristics is captivating. The aim of my master project in the continuous quest of the group of Prof. Eddaoudi in exploring different synthetic pathways to control the assembly of Rare Earth (RE) based MOF. After giving a general overview about MOFs, I will discuss in this thesis the results of my work on the use of tri-topic oriented organic carboxylate building units with the aim to explore the assembly/construction of new porous RE based MOFs. In chapter 2 will discuss the assembly of 3-c linkers with RE metals was then evaluated based on symmetry and angularity of the three connected linkers. The focus of chapter 3 is cerium based MOFs and heterometallic system, based on 3-c ligands with different length and symmetry. Overall, the incompatibility of 3-c ligands with the 12-c cuo MBB did not allow to any formation of higher neuclearity (˃6), but it has resulted in affecting the connectivity of the cluster.

  18. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Nandasiri, Manjula I.; Liu, Jian; McGrail, B. Peter; Jenks, Jeromy WJ; Schaef, Herbert T.; Shutthanandan, V.; Nie, Zimin; Martin, Paul F.; Nune, Satish K.

    2016-06-15

    Metal organic heat carriers (MOHCs) are recently developed nanofluids containing metal organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. MOHCs utilize the MOF properties to improve the thermo-physical properties of base fluids. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC containing MIL-101(Cr)/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with the intrinsic nano MIL-101(Cr) and the properties depend on the amount of GO added. Powder X-ray diffraction (PXRD) confirmed the preserved crystallinity of MIL-101(Cr) in all nanocomposites with the absence of any unreacted GO. Scanning electron microscopy images confirmed the presence of near spherical MIL-101(Cr) nanoparticles in the range of 40-80 nm in diameter. MOHC nanofluids containing MIL-101(Cr)/GO in methanol exhibited significant enhancement in the thermal conductivity (by approxi-mately 50%) relative to that of the intrinsic nano MIL-101(Cr) in methanol. The thermal conductivity of base fluid (methanol) was enhanced by about 20 %. The enhancement in the thermal conductivity of nanoMIL-101(Cr) MOHCs due to graphene oxide functionalization is explained using a classical Maxwell model.

  19. Research in the Field of Organic Photovoltaics at the Institute for Problems of Chemical Physics of Russian Academy of Sciences

    Science.gov (United States)

    Troshin, Pavel A.

    2015-08-01

    In the present review we highlight the main research activities in the field of organic photonics and photovoltaics at the Institute for Problems of Chemical Physics of Russian Academy of Sciences (IPCP RAS). Extensive investigation of optical and electrical properties of π-conjugated organic compounds performed at IPCP RAS since 1960's resulted in design of many exciting materials representing organic semiconductors, metals and superconductors. Organic Schottky barrier and p/n junction photovoltaic devices constructed at IPCP RAS in 1960's and 1970's were among the first examples of reasonably efficient organic solar cells at that time. These early discoveries inspired younger generations of the researchers to continue the work of their mentors and explore the world of organic materials and photonic devices such as molecular photonic switches, organic light emitting diodes, solar cells, photodetectors, photoswitchable organic field-effect transistors and memory elements.

  20. Relationship between chemical composition and oxidative potential of secondary organic aerosol from polycyclic aromatic hydrocarbons

    Directory of Open Access Journals (Sweden)

    S. Wang

    2018-03-01

    Full Text Available Owing to the complex nature and dynamic behaviors of secondary organic aerosol (SOA, its ability to cause oxidative stress (known as oxidative potential, or OP and adverse health outcomes remains poorly understood. In this work, we probed the linkages between the chemical composition of SOA and its OP, and investigated impacts from various SOA evolution pathways, including atmospheric oligomerization, heterogeneous oxidation, and mixing with metal. SOA formed from photooxidation of the two most common polycyclic aromatic hydrocarbons (naphthalene and phenanthrene were studied as model systems. OP was evaluated using the dithiothreitol (DTT assay. The oligomer-rich fraction separated by liquid chromatography dominates DTT activity in both SOA systems (52 ± 10 % for naphthalene SOA (NSOA, and 56 ± 5 % for phenanthrene SOA (PSOA. Heterogeneous ozonolysis of NSOA was found to enhance its OP, which is consistent with the trend observed in selected individual oxidation products. DTT activities from redox-active organic compounds and metals were found to be not additive. When mixing with highly redox-active metal (Cu, OP of the mixture decreased significantly for 1,2-naphthoquinone (42 ± 7 %, 2,3-dihydroxynaphthalene (35 ± 1 %, NSOA (50 ± 6 %, and PSOA (43 ± 4 %. Evidence from proton nuclear magnetic resonance (1H NMR spectroscopy illustrates that such OP reduction upon mixing can be ascribed to metal–organic binding interactions. Our results highlight the role of aerosol chemical composition under atmospheric aging processes in determining the OP of SOA, which is needed for more accurate and explicit prediction of the toxicological impacts from particulate matter.

  1. Integration of rigid and flexible organic parts for the construction of a homochiral metal-organic framework with high porosity.

    Science.gov (United States)

    Xu, Zhong-Xuan; Tan, Yan-Xi; Fu, Hong-Ru; Kang, Yao; Zhang, Jian

    2015-02-14

    Presented is a pair of homochiral metal-organic frameworks built from mixed ligands integrating rigid and flexible organic parts, and each compound shows high porosity and can be used for enantioselective separation of racemic 1-phenethylalcohol and methyl lactate.

  2. The dynamics of molecular interactions and chemical reactions at metal surfaces: testing the foundations of theory.

    Science.gov (United States)

    Golibrzuch, Kai; Bartels, Nils; Auerbach, Daniel J; Wodtke, Alec M

    2015-04-01

    We review studies of molecular interactions and chemical reactions at metal surfaces, emphasizing progress toward a predictive theory of surface chemistry and catalysis. For chemistry at metal surfaces, a small number of central approximations are typically made: (a) the Born-Oppenheimer approximation of electronic adiabaticity, (b) the use of density functional theory at the generalized gradient approximation level, (c) the classical approximation for nuclear motion, and (d) various reduced-dimensionality approximations. Together, these approximations constitute a provisional model for surface chemical reactivity. We review work on some carefully studied examples of molecules interacting at metal surfaces that probe the validity of various aspects of the provisional model.

  3. Morphology evolution and nanostructure of chemical looping transition metal oxide materials upon redox processes

    International Nuclear Information System (INIS)

    Qin, Lang; Cheng, Zhuo; Guo, Mengqing; Fan, Jonathan A.; Fan, Liang-Shih

    2017-01-01

    Transition metal are heavily used in chemical looping technologies because of their high oxygen carrying capacity and high thermal reactivity. These oxygen activities result in the oxide formation and oxygen vacancy formation that affect the nanoscale crystal phase and morphology within these materials and their subsequent bulk chemical behavior. In this study, two selected earlier transition metals manganese and cobalt as well as two selected later transition metals copper and nickel that are important to chemical looping reactions are investigated when they undergo cyclic redox reactions. We found Co microparticles exhibited increased CoO impurity presence when oxidized to Co 3 O 4 upon cyclic oxidation; CuO redox cycles prefer to be limited to a reduced form of Cu 2 O and an oxidized form of CuO; Mn microparticles were oxidized to a mixed phases of MnO and Mn 3 O 4 , which causes delamination during oxidation. For Ni microparticles, a dense surface were observed during the redox reaction. The atomistic thermodynamics methods and density functional theory (DFT) calculations are carried out to elucidate the effect of oxygen dissociation and migration on the morphological evolution of nanostructures during the redox processes. Our results indicate that the earlier transition metals (Mn and Co) tend to have stronger interaction with O 2 than the later transition metals (Ni and Cu). Also, our modified Brønsted−Evans−Polanyi (BEP) relationship for reaction energies and total reaction barriers reveals that reactions of earlier transition metals are more exergonic and have lower oxygen dissociation barriers than those of later transition metals. In addition, it was found that for these transition metal oxides the oxygen vacancy formation energies increase with the depth. The oxide in the higher oxidation state of transition metal has lower vacancy formation energy, which can facilitate forming the defective nanostructures. The fundamental understanding of these

  4. A metal-organic framework-based splitter for separating propylene from propane

    KAUST Repository

    Cadiau, Amandine

    2016-07-07

    The chemical industry is dependent on the olefin/paraffin separation, which is mainly accomplished by using energy-intensive processes. We report the use of reticular chemistry for the fabrication of a chemically stable fluorinated metal-organic framework (MOF) material (NbOFFIVE-1-Ni, also referred to as KAUST-7). The bridging of Ni(II)-pyrazine square-grid layers with (NbOF5)2- pillars afforded the construction of a three-dimensional MOF, enclosing a periodic array of fluoride anions in contracted square-shaped channels. The judiciously selected bulkier (NbOF5)2- caused the looked-for hindrance of the previously free-rotating pyrazine moieties, delimiting the pore system and dictating the pore aperture size and its maximum opening. The restricted MOF window resulted in the selective molecular exclusion of propane from propylene at atmospheric pressure, as evidenced through multiple cyclic mixed-gas adsorption and calorimetric studies.

  5. Metal-Organic Framework Thin Films as Stationary Phases in Microfabricated Gas-Chromatography Columns.

    Energy Technology Data Exchange (ETDEWEB)

    Read, Douglas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    The overarching goal of this project is to integrate Sandia's microfabricated gas-chromatography ( GC) columns with a stationary phase material that is capable of retaining high-volatility chemicals and permanent gases. The successful integration of such a material with GCs would dramatically expand the repertoire of detectable compounds for Sandia's various microanalysis systems. One such promising class of candidate materials is metal-organic frameworks (MOFs). In this report we detail our methods for controlled deposition of HKUST-1 MOF stationary phases within GC columns. We demonstrate: the chromatographic separation of natural gas; a method for determining MOF film thickness from chromatography alone; and the first-reported GC x GC separation of natural gas -- in general -- let alone for two disparate MOF stationary phases. In addition we determine the fundamental thermodynamic constant for mass sorption, the partition coefficient, for HKUST-1 and several light hydrocarbons and select toxic industrial chemicals.

  6. Transition Metal Catalyzed Reactions of Carbohydrates: a Nonoxidative Approach to Oxygenated Organics

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Mark

    1997-01-08

    There is a critical need for new environmentally friendly processes in the United States chemical industry as legislative and economic pressures push the industry to zero-waste and cradle-to-grave responsibility for the products they produce. Carbohydrates represent a plentiful, renewable resource, which for some processes might economically replace fossil feedstocks. While the conversion of biomass to fuels, is still not generally economical, the selective synthesis of a commodity or fine chemical, however, could compete effectively if appropriate catalytic conversion systems can be found. Oxygenated organics, found in a variety of products such as nylon and polyester, are particularly attractive targets. We believe that with concerted research efforts, homogeneous transition metal catalyzed reactions could play a significant role in bringing about this future green chemistry technology.

  7. Mechanistic Aspects in the Formation, Growth and Surface Functionalization of Metal Oxide Nanoparticles in Organic Solvents.

    Science.gov (United States)

    Deshmukh, Rupali; Niederberger, Markus

    2017-06-27

    The synthesis of metal oxide nanoparticles in organic solvents, so-called nonaqueous (or nonhydrolytic) processes represent powerful alternatives to aqueous approaches and have become an independent research field. 10 Years ago, when we published our first review on organic reaction pathways in nonaqueous sol-gel approaches, the number of examples was relatively limited. Nowadays, it is almost impossible to provide an exhaustive overview. Here we review the development of the last few years, without neglecting pioneering examples, which help to follow the historical development. The importance of a profound understanding of mechanistic aspects of nanoparticle crystallization and formation mechanisms can't be overestimated, when it comes to the design of rational synthesis concepts under minimization of trial-and-error experiments. The main reason for the progress in mechanistic understanding lies in the availability of characterization tools that make it possible to monitor chemical reactions from the dissolution of the precursor to the nucleation and growth of the nanoparticles, by ex situ methods involving sampling after different reaction times, but more and more also by in situ studies. After a short introduction to experimental aspects of nonaqueous sol-gel routes to metal oxide nanoparticles, we provide an overview of the main and basic organic reaction pathways in these approaches. Afterwards, we summarize the main characterization methods to study formation mechanisms, and then we discuss in great depth the chemical formation mechanisms of many different types of metal oxide nanoparticles. The review concludes with a paragraph on selected crystallization mechanisms reported for nonaqueous systems and a few illustrative examples of nonaqueous sol-gel concepts applied to surface chemistry. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Heavy metals and its chemical speciation in sewage sludge at different stages of processing.

    Science.gov (United States)

    Tytła, Malwina; Widziewicz, Kamila; Zielewicz, Ewa

    2016-01-01

    The analysis of heavy metal concentrations and forms in sewage sludge constitutes an important issue in terms of both health and environmental hazards the metals pose. The total heavy metals concentration enables only the assessment of its contamination. Hence the knowledge of chemical forms is required to determine their environmental mobility and sludge final disposal. Heavy metals speciation was studied by using four-stage sequential extraction BCR (Community Bureau of Reference). This study was aimed at determining the total concentration of selected heavy metals (Zn, Cu, Ni, Pb, Cd, Cr and Hg) and their chemical forms (except for Hg) in sludge collected at different stages of its processing at two municipal Wastewater Treatment Plants in southern Poland. Metals contents in sludge samples were determined by using flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). This study shows that Zn and Cu appeared to be the most abundant in sludge, while Cd and Hg were in the lowest concentrations. The sewage sludge revealed the domination of immobile fractions over the mobile ones. The oxidizable and residual forms were dominant for all the heavy metals. There was also a significant difference in metals speciation between sludges of different origin which was probably due to differences in wastewater composition and processes occurring in biological stage of wastewater treatment. The results indicate a negligible capability of metals to migrate from sludge into the environment. Our research revealed a significant impact of thickening, stabilization and hygienization on the distribution of heavy metals in sludge and their mobility.

  9. Modeling adsorption and reactions of organic molecules at metal surfaces.

    Science.gov (United States)

    Liu, Wei; Tkatchenko, Alexandre; Scheffler, Matthias

    2014-11-18

    CONSPECTUS: The understanding of adsorption and reactions of (large) organic molecules at metal surfaces plays an increasingly important role in modern surface science and technology. Such hybrid inorganic/organic systems (HIOS) are relevant for many applications in catalysis, light-emitting diodes, single-molecule junctions, molecular sensors and switches, and photovoltaics. Obviously, the predictive modeling and understanding of the structure and stability of such hybrid systems is an essential prerequisite for tuning their electronic properties and functions. At present, density-functional theory (DFT) is the most promising approach to study the structure, stability, and electronic properties of complex systems, because it can be applied to both molecules and solids comprising thousands of atoms. However, state-of-the-art approximations to DFT do not provide a consistent and reliable description for HIOS, which is largely due to two issues: (i) the self-interaction of the electrons with themselves arising from the Hartree term of the total energy that is not fully compensated in approximate exchange-correlation functionals, and (ii) the lack of long-range part of the ubiquitous van der Waals (vdW) interactions. The self-interaction errors sometimes lead to incorrect description of charge transfer and electronic level alignment in HIOS, although for molecules adsorbed on metals these effects will often cancel out in total energy differences. Regarding vdW interactions, several promising vdW-inclusive DFT-based methods have been recently demonstrated to yield remarkable accuracy for intermolecular interactions in the gas phase. However, the majority of these approaches neglect the nonlocal collective electron response in the vdW energy tail, an effect that is particularly strong in condensed phases and at interfaces between different materials. Here we show that the recently developed DFT+vdW(surf) method that accurately accounts for the collective electronic

  10. Content of metals and organic acids from experimental sparkling white wine

    Directory of Open Access Journals (Sweden)

    Focea Mihai Cristian

    2017-01-01

    Full Text Available This work is focused on the study of the influence of different strains of yeasts on the concentration of organic acids, metallic content, and other physical-chemical parameters from experimental sparkling white wines produced by traditional method (bottle fermented. This study was required due to climatic conditions varying from year to year, generating grape harvests with very high alcoholic potential, and very low values for total acidity. In this case, a Muscat Ottonel grape must was used and passed by a reverse osmosis process. The obtained permeate was mixed with a calculated amount of the concentrate to generate a must with a potential of 10.5% (v/v alcohol, in order o to obtain the base wine for the second fermentation. After fermentation, the wine was treated to get tartaric, protein and microbiological stabilization. For the second fermentation four different strains of yeast species Saccharomyces cerevisiae were used. Bottle fermentation and storage was performed at a constant temperature of approximately 12 °C. After six months of storage, sparkling wine samples were analyzed. The metal content was determined using AAS method, and organic acid concentration was determined by a HPLC method. The main physical-chemical characteristics were determined (alcohol concentration, total acidity, volatile acidity, total dry extract, free SO2, total SO2, density, pH, conductivity based on OIV methods. The results obtained indicated significant differences of the analyzed parameters.

  11. Metal presence influence on the efficiency of the organic compounds degradation caused by the electron beam irradiation

    International Nuclear Information System (INIS)

    Duarte, Celina Lopes; Oikawa, Hiroshi; Sampa, Maria Helena de Oliveira; Silveira, Carlos Gaia da; Ribeiro, Marcia Almeida; Sato, Ivone Mulako

    2002-01-01

    Actual industrial effluent from chemical, textile, pharmaceutical and painting industries has high level of organic compound, usually, together metals. The high efficiency of electron beam irradiation on removing organic compound in industrial effluent has been showed. A study to evaluate the Advanced Oxidation Process by electron beam irradiation to remove organic compound from simulated industrial effluent with two high metals concentration as Na, Cl, Ca, P, K, Si, Al, Zn, Fe, Mn, Cd, Pb, As e Hg, was carried out. The metals concentration was determined with the technique of Wavelength Dispersion X-Ray Spectrometry Fluorescence (WD-XRF). Experiments were conducted using a Radiation Dynamics Electron Beam Accelerator with 1,5 MeV energy and 37 kW power. The simulated effluent samples were irradiated in a batch system. The electron beam irradiation showed be efficient on destroying the organic compounds dichloroethane, methylisobutilketone, toluene, xylene, benzene, chloroform, tetrachloroethylene and trichloroethylene, even in presence of metals, but in this case the efficiency is decreased. To remove more than 90% of all organic compounds was necessary a 20 kGy dose for free metals samples and 50 kGy for the two simulated effluent samples. (author)

  12. Effects of Chemical Applications to Metal Polluted Soils on Cadmium Uptake by Rice Plant

    Directory of Open Access Journals (Sweden)

    Yoo J. H.

    2013-04-01

    Full Text Available Pot experiment using metal polluted soils was conducted to investigate the effects of lime, iron and sulfur on changes in Cd availability and uptake by rice plant. Drainage and irrigation of water were performed to develop redox changes like field cultivation. Iron chloride and sodium sulfate solutions were applied to the pots in the middle of growth period of rice plant. Reactive metal pool in heavily polluted soils was slightly decreased after treatments with lime, iron chloride, sodium sulfate and combination of these chemicals. However, cadmium uptake by rice plant was significantly different across the treatments and the extent of Cd pollution. For highly polluted soils, more Cd reduction was observed in iron chloride treatments. Cd content in polished rice for iron chloride and (iron chloride+organic matter treatments was only 16-23% and 25-37% compared to control and liming, respectively. Treatment of (iron chloride+sulfate rather increased Cd content in rice. For moderately polluted soils, Cd reduction rate was the order of (OM+iron chloride > iron chloride > lime. Other treatments including sulfate rather increased Cd content in rice maximum 3 times than control. It was proposed to determine the optimum application rate of iron for minimizing hazardous effect on rice plant.

  13. PREDICTING SOIL SORPTION COEFFICIENTS OF ORGANIC CHEMICALS USING A NEURAL NETWORK MODEL

    Science.gov (United States)

    The soil/sediment adsorption partition coefficient normalized to organic carbon (Koc) is extensively used to assess the fate of organic chemicals in hazardous waste sites. Several attempts have been made to estimate the value of Koc from chemical structure ...

  14. Reverse osmosis influence over the content of metals and organic acids in low alcoholic beverages

    Directory of Open Access Journals (Sweden)

    Andrieş Mitică Tiberiu

    2017-01-01

    Full Text Available Wine is defined as an alcoholic beverage resulted from fermentation of grape must, having ethanol content higher than 8.5% (v/v. Wine consumption has health benefits related to the high concentration of polyphenolic compounds with antioxidant activity and cardiovascular protection effects. However, the alcohol content restricts wine consumption, but wines with low-alcohol content can be obtained with the help of the dealcoholisation process, after it was produced through alcoholic fermentation. The purpose of this work is to evaluate the organic acid concentration, metal content and other physical-chemical parameters of low alcoholic beverages obtained from grape must by a process which involves reverse osmosis, mixing in a variable ratio the permeate and concentrate and then fermentation. For the experiments, a Muscat Ottonel grape must from Iaşi vineyard was used. There were ten variants of beverages (wines with low alcoholic concentration, by mixing known quantities of the two phases resulting from the reverse osmosis process. These beverages (wines had an alcoholic concentration starting from 2.5% (v/v in the first variant, up to 7% (v/v in the tenth variant. Alcoholic concentration varies for each variant by 0.5% (v/v. After fermentation in 50 L stainless steel tanks, the samples were filtered with 0.45μm sterile membrane and bottled in 0.75 L glass bottles. After 2 months of storage at constant temperature, the beverage samples were analyzed to determine the metal content (AAS method, organic acids concentration (HPLC method, and other physical-chemical characteristics (OIV standard methods. The results obtained indicate that the very complex physical-chemical composition of the low alcoholic beverages analyzed is influenced by the specific chemical composition of a given grape must, as well as by the use of products obtained from reverse osmosis.

  15. Electronic properties and chemistry of metal / organic semiconductor/ S-GaAs(100) heterosructures

    Energy Technology Data Exchange (ETDEWEB)

    Gavrila, G.N.

    2005-10-21

    in the framework of this thesis three perylene derivates are applied as interlayers in metal/organic layer/S-GaAs(100) heterostructures. The aim of this thesis is to prove the influence of different chemical end-groups on the electronic and chemical properties of the interfaces, as well as the molecular orientation in the organic layers. The molecules 3,4,9,10-perylene tetracarbonic acid dianhydride (PTCDA), 3,4,9,10-perylene tetracarbonic acid diimide (PTCDI), and dimethyl-3,4,9,10-perylene tetracarbonic acid diimide (DiMe-PTCDI) were evaporated by organic molecular beam deposition (OMBD) in the ultrahigh vacuum on sulfur-passivated GaAs(001):2 x 1 substrates. Surface-sensitive characterization procedures as photoemission spectroscopy (PES), inverse photoemission spectroscopy (IPES), and near-edge X-ray fine-structure measurements (NEXAFS) were applied for the characterization. Theoretical calculations by means of the density-functional methods were performed, in order to allow an assignment of different components in core-level spectra. The NEXAFS spectra allow a precise determination of the molecule orientation in relation to the substrate. So it can be proved that a small change of chemical end-groups for instance in DiMe-PTCDI compared with PTCDI causes a dramatic change of the molecule orientation. The valence-band spectra of DiMe-PTCDI show an energetic dispersion of 0.2 eV, which can be assigned to a {pi}-orbital overlap and covers the formation of valence bands. The energy-level fitting to the organic-layer/S-GaAs interface as well as the transport band gap of PTCDI, DiMe-PTCDI, and PTCDA were deteminde by means of PES and IPES. The electronic, chemical, and structural properties of metal/organic-layer interfaces were studied by means of core-level spectroscopy and NEXAFS. Mg reacts strongly with the end-groups of PTCDA AND ptcdi, while the In atoms contribute to a charge-transfer process with the perylene cores of all three molecules, whereby the

  16. Screening of perfluorinated chemicals (PFCs) in various aquatic organisms

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Sanjuan, Maria; Meyer, Johan; Damasio, Joana; Faria, Melissa; Barata, Carlos; Lacorte, Silvia [IDAEA-CSIC, Department of Environmental Chemistry, Barcelona (Spain)

    2010-10-15

    The aim of this study was to evaluate the occurrence of five perfluorinated chemicals (perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid) in aquatic organisms dwelling in either freshwater or marine ecosystems. Organisms selected were insect larvae, oysters, zebra mussels, sardines, and crabs, which are widespread in the environment and may represent potential bioindicators of exposure to PFCs. The study comprises the optimization of a solid-liquid extraction method and determination by high-performance liquid chromatography coupled to tandem mass spectrometry. Using spiked zebra mussels at 10 and 100 ng/g level, the method developed provided recoveries of 96% and 122%, and 82% to 116%, respectively, and a limit of detection between 0.07 and 0.22 ng/g ww. The method was highly sensitivity and robust to determine PFC compounds in a wide array of biological matrices, and no matrix interferents nor blank contamination was observed. Among organisms studied, none of the bivalves accumulated PFCs, and contrarily, insect larvae, followed by fish and crabs contained levels ranging from 0.23 to 144 ng/g ww of PFOS, from 0.14 to 4.3 ng/g ww of PFOA, and traces of PFNA and PFHxS. Assessment of the potential use of aquatic organisms for biomonitoring studies is further discussed. (orig.)

  17. Removal of hazardous organics from water using metal-organic frameworks (MOFs): plausible mechanisms for selective adsorptions.

    Science.gov (United States)

    Hasan, Zubair; Jhung, Sung Hwa

    2015-01-01

    Provision of clean water is one of the most important issues worldwide because of continuing economic development and the steady increase in the global population. However, clean water resources are decreasing everyday, because of contamination with various pollutants including organic chemicals. Pharmaceutical and personal care products, herbicides/pesticides, dyes, phenolics, and aromatics (from sources such as spilled oil) are typical organics that should be removed from water. Because of their huge porosities, designable pore structures, and facile modification, metal-organic frameworks (MOFs) are used in various adsorption, separation, storage, and delivery applications. In this review, the adsorptive purifications of contaminated water with MOFs are discussed, in order to understand possible applications of MOFs in clean water provision. More importantly, plausible adsorption or interaction mechanisms and selective adsorptions are summarized. The mechanisms of interactions such as electrostatic interaction, acid-base interaction, hydrogen bonding, π-π stacking/interaction, and hydrophobic interaction are discussed for the selective adsorption of organics over MOFs. The adsorption mechanisms will be very helpful not only for understanding adsorptions but also for applications of adsorptions in selective removal, storage, delivery and so on. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Modeling regional secondary organic aerosol using the Master Chemical Mechanism

    Science.gov (United States)

    Li, Jingyi; Cleveland, Meredith; Ziemba, Luke D.; Griffin, Robert J.; Barsanti, Kelley C.; Pankow, James F.; Ying, Qi

    2015-02-01

    A modified near-explicit Master Chemical Mechanism (MCM, version 3.2) with 5727 species and 16,930 reactions and an equilibrium partitioning module was incorporated into the Community Air Quality Model (CMAQ) to predict the regional concentrations of secondary organic aerosol (SOA) from volatile organic compounds (VOCs) in the eastern United States (US). In addition to the semi-volatile SOA from equilibrium partitioning, reactive surface uptake processes were used to simulate SOA formation due to isoprene epoxydiol, glyoxal and methylglyoxal. The CMAQ-MCM-SOA model was applied to simulate SOA formation during a two-week episode from August 28 to September 7, 2006. The southeastern US has the highest SOA, with a maximum episode-averaged concentration of ∼12 μg m-3. Primary organic aerosol (POA) and SOA concentrations predicted by CMAQ-MCM-SOA agree well with AMS-derived hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) urban concentrations at the Moody Tower at the University of Houston. Predicted molecular properties of SOA (O/C, H/C, N/C and OM/OC ratios) at the site are similar to those reported in other urban areas, and O/C values agree with measured O/C at the same site. Isoprene epoxydiol is predicted to be the largest contributor to total SOA concentration in the southeast US, followed by methylglyoxal and glyoxal. The semi-volatile SOA components are dominated by products from β-caryophyllene oxidation, but the major species and their concentrations are sensitive to errors in saturation vapor pressure estimation. A uniform decrease of saturation vapor pressure by a factor of 100 for all condensable compounds can lead to a 150% increase in total SOA. A sensitivity simulation with UNIFAC-calculated activity coefficients (ignoring phase separation and water molecule partitioning into the organic phase) led to a 10% change in the predicted semi-volatile SOA concentrations.

  19. Iron Catalysis in Organic Synthesis: A Critical Assessment of What It Takes To Make This Base Metal a Multitasking Champion

    Science.gov (United States)

    2016-01-01

    The current status of homogeneous iron catalysis in organic chemistry is contemplated, as are the reasons why this particular research area only recently starts challenging the enduring dominance of the late and mostly noble metals over the field. Centered in the middle of the d-block and able to support formal oxidation states ranging from −II to +VI, iron catalysts hold the promise of being able to encompass organic synthesis at large. They are expected to serve reductive as well as oxidative regimes, can emulate “noble tasks”, but are also able to adopt “early” transition metal character. Since a comprehensive coverage of this multidimensional agenda is beyond the scope of an Outlook anyway, emphasis is laid in this article on the analysis of the factors that perhaps allow one to control the multifarious chemical nature of this earth-abundant metal. The challenges are significant, not least at the analytical frontier; their mastery mandates a mindset that differs from the routines that most organic chemists interested in (noble metal) catalysis tend to cultivate. This aspect notwithstanding, it is safe to predict that homogeneous iron catalysis bears the chance to enable a responsible paradigm for chemical synthesis and a sustained catalyst economy, while potentially providing substantial economic advantages. This promise will spur the systematic and in-depth investigations that it takes to upgrade this research area to strategy-level status in organic chemistry and beyond. PMID:27981231

  20. Interaction of Hydroxyproline with Bivalent Metal Ions in Chemical ...

    African Journals Online (AJOL)

    Arecent technique involving the use of paper electrophoresis is described for the study of equilibria in binary complex systems in solution. The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were determined in 0.1 mol L–1 perchloric acid ...

  1. 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

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

    Science.gov (United States)

    Deng, Xiaoyu; Li, Zhaohui; García, Hermenegildo

    2017-08-22

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

  3. Chemical properties of heavy metals in typical hospital waste incinerator ashes in China.

    Science.gov (United States)

    Zhao, Lijuan; Zhang, Fu-Shen; Wang, Kaisheng; Zhu, Jianxin

    2009-03-01

    Incineration has become the main mechanism for hospital waste (HW) disposal in China after the outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003. However, little information is available on the chemical properties of the resulting ashes. In the present study, 22HW ash samples, including 14 samples of bottom ash and eight samples of fly ash, were collected from four typical HW incineration plants located across China. Chemical analysis indicated that the HW ashes contained large amounts of metal salts of Al, Ca, Fe, K, Mg, Na with a concentration range of 1.8-315gkg(-1). Furthermore, the ashes contained high concentrations of heavy metals such as Ag, As, Ba, Bi, Cd, Cr, Cu, Mn, Ni, Pb, Ti, Sb, Sn, Sr, Zn with a vast range of 1.1-121,411mgkg(-1), with higher concentrations found in the fly ash samples. Sequential extraction results showed that Ba, Cr, Ni and Sn are present in the residual fraction, while Cd existed in the exchangeable and carbonate fractions. As, Mn, Zn existed in the Fe-Mn oxide fraction, Pb was present in the Fe-Mn oxide and residual fractions, and Cu was present in the organic matter fraction. Furthermore, toxicity characteristic leaching procedure (TCLP) results indicated that leached amounts of Cd, Cu and Pb from almost all fly ash samples exceeded the USEPA regulated levels. A comparison between the HW ashes and municipal solid waste (MSW) ash showed that both HW bottom ash and fly ash contained higher concentrations of Ag, As, Bi, Cd, Cr, Cu, Pb, Ti, and Zn. This research provides critical information for appropriate HW incineration ash management plans.

  4. Bioremediation of metals, organic and mixed contaminants with microbial mats

    Energy Technology Data Exchange (ETDEWEB)

    Bender, J.

    1995-12-31

    Microbial mats are natural heterotrophic and autotrophic communities dominated by cyanobacteria (blue-green algae). They are self-organized laminated structures annealed tightly together by slimy secretions from various microbial components. The surface slime of the mats effectively immobilizes the ecosystem to a variety of substrates, thereby stabilizing the most efficient internal microbial structure. Cyanobacteria mats are generated for bioremediation applications by enriching a water surface with ensiled grass clippings. These constructed mats have been used to reduce selenate to elemental selenium, remove Pb, Cd, Cu, Zn, Co, Cr, Fe and Mn from water and to remove Pb from sediments of shallow laboratory ponds. Uranium, U{sup 238}, was removed from groundwater samples at the rate of 3.19 Mg/m{sup 2}/h. Degradation of recalcitrant organic contaminants by mats is relatively rapid under both dark and light conditions. The following contaminants have been degraded in water and/or soil media by constructed mats: TNT, chrysene, naphthalene, hexadecane, phenanthrene, PCB, TCE, pulp and paper mill wastes, and three pesticides: chlordane, carbofuran and paraquat. Radio-labeled experiments with mat-treated carbofuran, petroleum distillates, TNT, chlordane, PCB and TCE show that these compounds are mineralized by the constructed mats. Mats applied to mixed contaminant solutions (TCE + Zn and TNT + pb) sequestered the metal while mineralizing the TCE. Remediation rates of the organic and inorganic components were the same in mixed solution as they were in single application.

  5. Improving Molecular Level Chemical Speciation of Organic Aerosols

    Science.gov (United States)

    Worton, D. R.; Decker, M.; Isaacman, G. A.; Chan, A.; Wilson, K. R.; Goldstein, A. H.

    2013-12-01

    A substantial fraction of fine mode aerosols are organic with the majority formed in the atmosphere through oxidation of gas phase compounds emitted from a variety of natural and man-made sources. As a result, organic aerosols are comprised of thousands of individual organic species whose complexity increases exponentially with carbon number and degree of atmospheric oxidation. Chemical characterization of individual compounds present in this complex mixture provides information on sources and transformation processes that are critical for apportioning organic carbon from an often convoluted mixture of sources and to constrain oxidation mechanisms needed for atmospheric models. These compounds also affect the physical and optical properties of the aerosol but the vast majority remain unidentified and missing from published mass spectral libraries because of difficulties in separating and identifying them. We have developed improved methodologies for chemical identification in order to better understand complex environmental mixtures. Our approach has been to combine two-dimensional gas chromatography with high resolution time of flight mass spectrometry (GC×GC-HRTOFMS) and both traditional electron ionization (EI) and vacuum ultraviolet (VUV) photoionization. GC×GC provides improved separation of individual compounds over traditional one dimensional GC and minimizes co-elution of peaks resulting in mass spectra that are virtually free of interferences. VUV ionization is a ';soft' ionization technique that reduces fragmentation and enhances the abundance of the parent or molecular ion, which when combined with high resolution mass spectrometry can provide molecular formulas for chromatographic peaks. We demonstrate our methodology by applying it to identify more than 500 individual compounds in aerosol filter samples collected at Blodgett Forest, a rural site in the Sierra Nevada Mountains. Using the EI NIST mass spectral library and molecular formulas determined

  6. Surface nano-architecture of a metal-organic framework.

    Science.gov (United States)

    Makiura, Rie; Motoyama, Soichiro; Umemura, Yasushi; Yamanaka, Hiroaki; Sakata, Osami; Kitagawa, Hiroshi

    2010-07-01

    The rational assembly of ultrathin films of metal-organic frameworks (MOFs)--highly ordered microporous materials--with well-controlled growth direction and film thickness is a critical and as yet unrealized issue for enabling the use of MOFs in nanotechnological devices, such as sensors, catalysts and electrodes for fuel cells. Here we report the facile bottom-up fabrication at ambient temperature of such a perfect preferentially oriented MOF nanofilm on a solid surface (NAFS-1), consisting of metalloporphyrin building units. The construction of NAFS-1 was achieved by the unconventional integration in a modular fashion of a layer-by-layer growth technique coupled with the Langmuir-Blodgett method. NAFS-1 is endowed with highly crystalline order both in the out-of-plane and in-plane orientations to the substrate, as demonstrated by synchrotron X-ray surface crystallography. The proposed structural model incorporates metal-coordinated pyridine molecules projected from the two-dimensional sheets that allow each further layer to dock in a highly ordered interdigitated manner in the growth of NAFS-1. We expect that the versatility of the solution-based growth strategy presented here will allow the fabrication of various well-ordered MOF nanofilms, opening the way for their use in a range of important applications.

  7. Controlling Thermal Expansion: A Metal-Organic Frameworks Route.

    Science.gov (United States)

    Balestra, Salvador R G; Bueno-Perez, Rocio; Hamad, Said; Dubbeldam, David; Ruiz-Salvador, A Rabdel; Calero, Sofia

    2016-11-22

    Controlling thermal expansion is an important, not yet resolved, and challenging problem in materials research. A conceptual design is introduced here, for the first time, for the use of metal-organic frameworks (MOFs) as platforms for controlling thermal expansion devices that can operate in the negative, zero, and positive expansion regimes. A detailed computer simulation study, based on molecular dynamics, is presented to support the targeted application. MOF-5 has been selected as model material, along with three molecules of similar size and known differences in terms of the nature of host-guest interactions. It has been shown that adsorbate molecules can control, in a colligative way, the thermal expansion of the solid, so that changing the adsorbate molecules induces the solid to display positive, zero, or negative thermal expansion. We analyze in depth the distortion mechanisms, beyond the ligand metal junction, to cover the ligand distortions, and the energetic and entropic effect on the thermo-structural behavior. We provide an unprecedented atomistic insight on the effect of adsorbates on the thermal expansion of MOFs as a basic tool toward controlling the thermal expansion.

  8. Xenon Recovery at Room Temperature using Metal-Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Elsaidi, Sameh K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Ongari, Daniele [Laboratory of Molecular Simulation, Institut des Sciences et Ingeénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l' Industrie 17 1951 Sion Valais Switzerland; Xu, Wenqian [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Mohamed, Mona H. [Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Haranczyk, Maciej [IMDEA Materials Institute, c/Eric Kandel 2 28906 Getafe, Madrid Spain; Thallapally, Praveen K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2017-07-24

    Xenon is known to be a very efficient anesthetic gas but its cost prohibits the wider use in medical industry and other potential applications. It has been shown that Xe recovery and recycle from anesthetic gas mixture can significantly reduce its cost as anesthetic. The current technology uses series of adsorbent columns followed by low temperature distillation to recover Xe, which is expensive to use in medical facilities. Herein, we propose much efficient and simpler system to recover and recycle Xe from simulant exhale anesthetic gas mixture at room temperature using metal organic frameworks. Among the MOFs tested, PCN-12 exhibits unprecedented performance with high Xe capacity, Xe/O2, Xe/N2 and Xe/CO2 selectivity at room temperature. The in-situ synchrotron measurements suggest the Xe is occupied in the small pockets of PCN-12 compared to unsaturated metal centers (UMCs). Computational modeling of adsorption further supports our experimental observation of Xe binding sites in PCN-12.

  9. Studies on chemical phenomena of high concentration tritium water and organic compounds of tritium from viewpoint of the tritium confinement

    International Nuclear Information System (INIS)

    Yamanishi, Toshihiko; Hayashi, Takumi; Iwai, Yasunori; Isobe, Kanetsugu; Hara, Masanori; Sugiyama, Takahiko; Okuno, Kenji

    2009-01-01

    As a part of the grant-in-aid for scientific research on priority areas entitled 'frontiers of tritium researches toward fusion reactors', coordinated two research programs on chemical phenomena of high concentration tritium water and organic compounds of tritium from view point of the tritium confinement have been conducted by the C01 team. The results are summarized as follows: (1) Chemical effects of the high concentration tritium water on stainless steels as structural materials of fusion reactors were investigated. Basic data on tritium behaviors at the metal-water interface and corrosion of metal in tritium water were obtained. (2) Development of the tritium confinement and extraction system for the circulating cooling water in the fusion reactor was studied. Improvement was obtained in the performance of a chemical exchange column and catalysts as major components of the water processing system. (J.P.N.)

  10. Ordered macro-microporous metal-organic framework single crystals

    Science.gov (United States)

    Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

    2018-01-01

    We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional–ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent–induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

  11. Enzyme-MOF (metal-organic framework) composites.

    Science.gov (United States)

    Lian, Xizhen; Fang, Yu; Joseph, Elizabeth; Wang, Qi; Li, Jialuo; Banerjee, Sayan; Lollar, Christina; Wang, Xuan; Zhou, Hong-Cai

    2017-06-06

    The ex vivo application of enzymes in various processes, especially via enzyme immobilization techniques, has been extensively studied in recent years in order to enhance the recyclability of enzymes, to minimize enzyme contamination in the product, and to explore novel horizons for enzymes in biomedical applications. Possessing remarkable amenability in structural design of the frameworks as well as almost unparalelled surface tunability, Metal-Organic Frameworks (MOFs) have been gaining popularity as candidates for enzyme immobilization platforms. Many MOF-enzyme composites have achieved unprecedented results, far outperforming free enzymes in many aspects. This review summarizes recent developments of MOF-enzyme composites with special emphasis on preparative techniques and the synergistic effects of enzymes and MOFs. The applications of MOF-enzyme composites, primarily in transferation, catalysis and sensing, are presented as well. The enhancement of enzymatic activity of the composites over free enzymes in biologically incompatible conditions is emphasized in many cases.

  12. Ordered macro-microporous metal-organic framework single crystals

    KAUST Repository

    Shen, Kui

    2018-01-16

    We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

  13. One-step surface selective modification of UV-curable hard coatings with photochemical metal organics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yoon Kwang; Park, Chang-Sun; Park, Hyung-Ho, E-mail: hhpark@yonsei.ac.kr

    2016-12-15

    Graphical abstract: This study demonstrates suitable for exceptional hybrid film under UV exposure. A small quantity of the dispersive photochemical precursor Sr 2-ethylhexanoate was mixed and the composition altered from the surface to the bottom, forming an organic layer and a densely concentrated SrO surface layer. The surface-selective SrO strongly enhanced the surface flatness and hardness of the UV-curable organic coating film. - Highlights: • Hybrid bi-layer coating was synthesized through one-pot UV exposure chemical route. • The influence of additive and different reactivity formed densely concentrated SrO surface layer. • Chemical composition and continuous interface between organic and inorganic were analyzed. • Surface flatness and mechanical property were improved by inorganic material. - Abstract: An organic–inorganic hybrid bi-layer film with a selective distribution of inorganic components was synthesized from a one-pot process of UV irradiation. A photochemical metal oxide precursor (Sr 2-ethylhexanoate) varying from 0 to 4 wt% was dispersed in UV-curable coating materials. Under UV exposure, the bi-layer started reacting simultaneously but at different rates due to differences in the two UV-condensable components’ reactivity. The effects of the dispersed inorganic component on the surface morphology and mechanical properties were investigated by atomic force microscopy and nanoindentation, respectively. The reaction process and rates were studied from linkage change using Fourier transform infrared spectroscopy at various UV exposure times (0–30 min). The elemental distribution and the interface on the coating layer were characterized by X-ray photoelectron spectroscopy from Ar etching, revealing continuous and gradual composition changes in depth. The results showed that a flattened and surface-selectively hardened SrO containing the coating film could be obtained by this simple process. Consequently, a small ratio of photochemical

  14. Metallization on FDM Parts Using the Chemical Deposition Technique

    OpenAIRE

    Azhar Equbal; Anoop kumar Sood

    2014-01-01

    Metallization of ABS (acrylonitrile-butadiene-styrene) parts has been studied on flat part surfaces. These parts are fabricated on an FDM (fused deposition modeling machine) using the layer-wise deposition principle using ABS as a part material. Electroless copper deposition on ABS parts was performed using two different surface preparation processes, namely ABS parts prepared using chromic acid for etching and ABS parts prepared using a solution mixture of sulphuric acid and hydrogen peroxid...

  15. Formation of amorphous metal alloys by chemical vapor deposition

    Science.gov (United States)

    Mullendore, Arthur W.

    1990-01-01

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures or organometallic compounds and metalloid hydrides, e.g., transition metal carbonyl such as nickel carbonyl, and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit.

  16. Role of Organic Matter in the Removal of Heavy Metals in Stormwater Runoff

    Science.gov (United States)

    Barrett, M.; Ingenloff, C.; Katz, L.

    2011-12-01

    Heavy metals (copper, zinc, and lead) are common constituents in highway runoff and concentrations in runoff from highway facilities are particularly high. These concentrations are also generally higher than observed in natural water bodies and several studies have demonstrated acute and chronic toxicity to aquatic ecosystems. One focus of this project is to assess the potential of sorption to reduce the concentration of metals in runoff. The difficulty evaluating adsorption in multi-component systems is to capture the impacts of background organic matter and other complexing ions on adsorption behavior. Very few studies have evaluated the ability of surface complexation models to predict adsorption in systems that contain organic matter from highway runoff. Moreover, the composition of the organic matter in stormwater runoff can be significantly different from natural organic matter typically used to assess the impact of background organics on metal ion adsorption. This research project specifically addresses these concerns and examines the impact of highway runoff on the adsorption behavior to determine whether existing surface complexation and chemical speciation models and parameter databases can be used to predict adsorption of target metal ions in these waters. Previous research has employed both actual storm water that has been obtained from actual field highway runoff sites as well as synthetic storm water compositions that have attempted to mimic the major components of natural storm water. Researchers and practitioners in the field generally agree on the importance of capturing the background water matrix; however, concerns associated with required volumes, holding times, aging, consistency and temporal and spatial variability often favor the use of synthetic formulations. While synthetic storm water can achieve the required consistency, numerous artifacts can be introduced due to the high reactivity of trace metal ions with background inorganic and

  17. Chemical-disorder effects in half-metallic Heusler alloys

    Science.gov (United States)

    Skomski, Ralph; Jin, Yunlong; Waybright, Jace; Kharel, Parashu; Pathak, Rohit; Choudhary, Renu; Kashyap, Arti; Sellmyer, D. J.

    The electronic structure, magnetism, and conductivity of disordered Heusler alloys are investigated theoretically and experimentally. Emphasis is on Heuslers that are predicted to be half-metallic or spin-gapless semiconducting in their fully ordered states, such as CoFeCrAl. Experimental alloys often exhibit resistivities of the order of 200 μΩ cm, which is consistent with both dirty-metal and spin-gapless semiconducting behaviors, but a distinction can be made by comparing the residual resistivities of samples having different degrees of order. The corresponding analysis shows that careful processing is necessary to keep the alloys in the spin-gapless semiconducting regime. Several types of disorder occur in Y-type Heusler alloys, with different negative effects on half-metallicity and spin-gapless semiconductivity. A2 (or bcc) disorder is most harmful but can be limited experimentally in CoFeCrAl thin films. B2 (or CsCl) disorder is less harmful, whereas L21 (normal Heusler) disorder, corresponding to Fe-Co solid solubility is least harmful. The residual resistivity of the partially diorderd alluys is discussed as a carrier-localization effect. This work is supported by DOE BES (DE-FG02-04ER46152, R.S.) and NSF DMREF (SusChEM 1436385, D.J.S.).

  18. Aqueous organic chemistry in the atmosphere: sources and chemical processing of organic aerosols.

    Science.gov (United States)

    McNeill, V Faye

    2015-02-03

    Over the past decade, it has become clear that aqueous chemical processes occurring in cloud droplets and wet atmospheric particles are an important source of organic atmospheric particulate matter. Reactions of water-soluble volatile (or semivolatile) organic gases (VOCs or SVOCs) in these aqueous media lead to the formation of highly oxidized organic particulate matter (secondary organic aerosol; SOA) and key tracer species, such as organosulfates. These processes are often driven by a combination of anthropogenic and biogenic emissions, and therefore their accurate representation in models is important for effective air quality management. Despite considerable progress, mechanistic understanding of some key aqueous processes is still lacking, and these pathways are incompletely represented in 3D atmospheric chemistry and air quality models. In this article, the concepts, historical context, and current state of the science of aqueous pathways of SOA formation are discussed.

  19. Molecular simulations of self-assembly processes in metal-organic frameworks: Model dependence

    Science.gov (United States)

    Biswal, Debasmita; Kusalik, Peter G.

    2017-07-01

    Molecular simulation is a powerful tool for investigating microscopic behavior in various chemical systems, where the use of suitable models is critical to successfully reproduce the structural and dynamic properties of the real systems of interest. In this context, molecular dynamics simulation studies of self-assembly processes in metal-organic frameworks (MOFs), a well-known class of porous materials with interesting chemical and physical properties, are relatively challenging, where a reasonably accurate representation of metal-ligand interactions is anticipated to play an important role. In the current study, we both investigate the performance of some existing models and introduce and test new models to help explore the self-assembly in an archetypal Zn-carboxylate MOF system. To this end, the behavior of six different Zn-ion models, three solvent models, and two ligand models was examined and validated against key experimental structural parameters. To explore longer time scale ordering events during MOF self-assembly via explicit solvent simulations, it is necessary to identify a suitable combination of simplified model components representing metal ions, organic ligands, and solvent molecules. It was observed that an extended cationic dummy atom (ECDA) Zn-ion model combined with an all-atom carboxylate ligand model and a simple dipolar solvent model can reproduce characteristic experimental structures for the archetypal MOF system. The successful use of these models in extensive sets of molecular simulations, which provide key insights into the self-assembly mechanism of this archetypal MOF system occurring during the early stages of this process, has been very recently reported.

  20. Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

    International Nuclear Information System (INIS)

    Bory, Benjamin F.; Meskers, Stefan C. J.; Rocha, Paulo R. F.; Gomes, Henrique L.; Leeuw, Dago M. de

    2015-01-01

    Diodes incorporating a bilayer of an organic semiconductor and a wide bandgap metal oxide can show unipolar, non-volatile memory behavior after electroforming. The prolonged bias voltage stress induces defects in the metal oxide with an areal density exceeding 10 17  m −2 . We explain the electrical bistability by the coexistence of two thermodynamically stable phases at the interface between an organic semiconductor and metal oxide. One phase contains mainly ionized defects and has a low work function, while the other phase has mainly neutral defects and a high work function. In the diodes, domains of the phase with a low work function constitute current filaments. The phase composition and critical temperature are derived from a 2D Ising model as a function of chemical potential. The model predicts filamentary conduction exhibiting a negative differential resistance and nonvolatile memory behavior. The model is expected to be generally applicable to any bilayer system that shows unipolar resistive switching

  1. Physico-chemical characteristics and Heavy metal levels in Drinking ...

    African Journals Online (AJOL)

    Michael Horsfall

    ABSTRAC: This study investigated the physico-chemical characteristics of drinking waters collected from tap, well and sachet in Sokoto metropolis in North Western Nigeria. Conductivity and pH values were determined by standard methods while elemental composition was analysed using X-ray Fluorescence spectroscopy ...

  2. Levels of Some Heavy Metals and Physico Chemical Properties of ...

    African Journals Online (AJOL)

    MICHAEL

    REFERENCES. Adeyinka, J S (1996). Waste water treatment through reverse osmosis. Env. Monitoring and. Assessment. 22-37. Adinna, E N ;Ekop, O B and Attah, V I (2003). Environmental pollution and management in the tropics. Metroprints Publishers – Uyo. 12 -21. Ansa – Asare, O D (1992). Chemical. Characterization.

  3. Levels of Some Heavy Metals and Physico Chemical Properties of ...

    African Journals Online (AJOL)

    In this study, the concentrations of selected heavy meyals and physico-chemical characteristics of effluents from a beverage company in Rivers State, Nigeria and those of the receiving Woji River were evaluated to ascertain the efficiency of the company's waste treatment processes. The results showed that the contents of ...

  4. Physico-chemical properties and heavy metal content of water ...

    African Journals Online (AJOL)

    user

    The water quality examination in Ife–North Local Government of Osun State Nigeria was conducted by determining the physico–chemical parameters of 40 samples. Surface water, bore holes, wells and pipe borne water samples were collected from major towns in the Local Government Area and analyzed. Results showed ...

  5. 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.

  6. Functionalization of silicon nanowire surfaces with metal-organic frameworks

    KAUST Repository

    Liu, Nian

    2011-12-28

    Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  7. Organic waste as a sustainable feedstock for platform chemicals.

    Science.gov (United States)

    Coma, M; Martinez-Hernandez, E; Abeln, F; Raikova, S; Donnelly, J; Arnot, T C; Allen, M J; Hong, D D; Chuck, C J

    2017-09-21

    Biorefineries have been established since the 1980s for biofuel production, and there has been a switch lately from first to second generation feedstocks in order to avoid the food versus fuel dilemma. To a lesser extent, many opportunities have been investigated for producing chemicals from biomass using by-products of the present biorefineries, simple waste streams. Current facilities apply intensive pre-treatments to deal with single substrate types such as carbohydrates. However, most organic streams such as municipal solid waste or algal blooms present a high complexity and variable mixture of molecules, which makes specific compound production and separation difficult. Here we focus on flexible anaerobic fermentation and hydrothermal processes that can treat complex biomass as a whole to obtain a range of products within an integrated biorefinery concept.

  8. Anaerobic sediment potential acidification and metal release risk assessment by chemical characterization and batch resuspension experiments

    Energy Technology Data Exchange (ETDEWEB)

    Nanno, M.P. di [Univ. de San Martin, Buenos Aires (Argentina). Escuela de Ciencia y Technologia; Curutchet, G. [Univ. de San Martin, Buenos Aires (Argentina). Escuela de Ciencia y Technologia; CONICET, Buenos Aires (Argentina); Ratto, S. [Univ. de Buenos Aires (Argentina). Catedra de Edafologia

    2007-06-15

    Background, Aim and Scope: Sediments act as a sink for toxic substances (heavy metals, organic pollutants) and, consequently, dredged materials often contain pollutants which are above safe limits. In polluted anaerobic sediments, the presence of sulphides and redox potential changes creates a favorable condition for sulphide oxidation to sulphate, resulting in potential toxic metal release. The oxidation reaction is catalyzed by several microorganisms. Some clean up measures, such as dredging, can initiate the process. The aim of the present work is to assess the acidification and metal release risk in the event of sediment dredging and also to compare two different acid base account techniques with the resuspension results. The oxidation mechanism by means of inoculation with an Acidithiobacillus ferrooxidans strain was also evaluated. Materials and Methods: The sediments were chemically characterized (pH; organic oxidizable carbon; acid volatile sulphides; total sulphur; moisture; Cr, Cu and Zn aqua regia contents). A metal sequential extraction procedure (Community Bureau of Reference, BCR technique) was applied to calculate the Acid Producing Potential (APP) and Acid Consuming Capacity (ACC) of the sediment samples through Fe, Ca{sup 2+} and SO{sub 4}{sup 2-} measurements. The acid base account was also performed by the Sobek methodology (Acid producing potential - AP - calculated with total sulphur and neutralization potential - NP - by titration of the remaining acid after a reaction period with the sample). Fresh sediments were placed in agitated shake flasks and samples were taken at different times to evaluate pH, SO{sub 4}{sup 2-} and Cr, Cu, Zn and Fe{sup 2+} concentration. Some of the systems were inoculated with an Acidithiobacillus ferrooxidans strain to assess the biological catalysis on sulphide oxidation. Results: Sediment chemical characterization showed high organic matter content (5.4-10.6%), total sulphur (0.36-0.86%) and equivalent CaCO{sub 3

  9. Chemical and Molecular Characterization of Biofilm on Metal Surfaces

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.

    in seawater. Biofouling 17, 129 145. Cowie, G.L., Hedges, J.I., 1984. Carbohydrates sources in a coastal marine environment. Geochimica et Cosmochimica Acta 48, 2075 2087. Cowie, G.L., Hedges, J.I., Prahl, F.G., deLange, G.J., 1995. Elemental... to assess development of conditioning film and biofilm on metal surfaces (Bhosle et al., 1989; Bhosle et al., 1990; Sonak and Bhosle, 1995; Bhosle and Wagh, 1997, D?Souza and Bhosle, 2003). This chapter is a compilation of relevant information...

  10. New metal-organic nanomaterials synthesized by laser irradiation of organic liquids

    International Nuclear Information System (INIS)

    Kuzmin, Stanislav L.; Wesolowski, Michal J.; Duley, Walter W.

    2014-01-01

    A new type of metal-organic composition consisting of clusters of nanoparticles has been synthesised by laser irradiation of metallocene/benzene solutions. The metallocene molecules in this reaction become the source of the metal. Exposure to high-energy femtosecond laser pulses dehydrogenate benzene molecules and initiate the high-temperature high-pressure conditions that results in the synthesis of new materials. Irradiation experiments have been carried out on ferrocene/benzene and on other solutions. With ferrocene the synthesis of a new compound has been confirmed by X-ray powder diffraction as the peaks detected do not correspond to any known substance in the Crystallography Open Database. Theoretical simulation of the periodic structure of this new carbide predicts that it has hexagonal symmetry and a unit cell with a = 3.2A and c =2.8A. The exact structure is still uncertain but may be determined from scanning tunneling microscope (STM) studies

  11. Tracing the Chemical Evolution of Metal-rich Galactic Bulge Globular Clusters

    Science.gov (United States)

    Munoz Gonzalez, Cesar; Saviane, Ivo; Geisler, Doug; Villanova, Sandro

    2018-01-01

    We present in this poster the metallicity characterization of the four metal rich Bulge Galactic Gobular Clusters, which have controversial metallicities. We analyzed our high-resolution spectra (using UVES-580nm and GIRAFFE-HR13 setups) for a large sample of RGB/AGB targets in each cluster in order to measure their metallicity and prove or discard the iron spread hypothesis. We have also characterized chemically stars with potentially different iron content by measuring light (O, Na, Mg, Al), alpha (Si, Ca, Ti), iron–peak (V, Cr, Ni, Mn) and s and r process (Y, Zr, Ba, Eu) elements. We have identified possible channels responsible for the chemical heterogeneity of the cluster populations, like AGB or massive fast-rotating stars contamination, or SN explosion. Also, we have analyzed the origin and evolution of these bulge GCs and their connection with the bulge itself.

  12. Trends in the chemical properties in early transition metal carbide surfaces: A density functional study

    DEFF Research Database (Denmark)

    Kitchin, J.R.; Nørskov, Jens Kehlet; Barteau, M.A.

    2005-01-01

    In this paper we present density functional theory (DFT) investigations of the physical, chemical and electronic structure properties of several close-packed surfaces of early transition metal carbides, including beta-Mo2C(0 0 0 1), and the (1 1 1) surfaces of TiC, VC, NbC, and TaC. The results...... are in excellent agreement with experimental values of lattice constants and bulk moduli. The adsorption of atomic hydrogen is used as a probe to compare the chemical properties of various carbide surfaces. Hydrogen adsorbs more strongly to the metal-terminated carbide surfaces than to the corresponding closest......-packed pure metal surfaces, due to the tensile strain induced in the carbide surfaces upon incorporation of carbon into the lattice. Hydrogen atoms were found to adsorb more weakly on carbide surfaces than on the corresponding closest-packed pure metal surfaces only when there were surface carbon atoms...

  13. Optimization of coupled plasmonic effects for viable phosphorescence of metal-free purely organic phosphor

    Science.gov (United States)

    Wang, Huan; Jung, Jaehun; Chung, Kyungwha; Lim, Ju Won; You, Youngmin; Kim, Jinsang; Kim, Dong Ha

    2017-10-01

    Metal-free purely organic phosphorescent molecules are attractive alternatives to organometallic and inorganic counterparts because of their low cost and readily tunable optical properties through a wide chemical design window. However, their weak phosphorescent intensity due to inefficient spin-orbit coupling and, consequently, prevailing non-radiative decay processes limit their practical applicability. Here, we systematically studied phosphorescence emission enhancement of a purely organic phosphor system via plasmon resonance energy transfer. By precisely tuning the distance between purely organic phosphor crystals and plasmonic nanostructures using layer-by-layer assembled polyelectrolyte multilayers as a dielectric spacer, maximum 2.8 and 2.5 times enhancement in photoluminescence intensity was observed when the phosphor crystals were coupled with ˜55 nm AuNPs and ˜7 nm AgNPs, respectively, at the distance of 9.6 nm. When the distance is within the range of 3 nm, a dramatic decrease in phosphorescence intensity was observed, while at a larger distance, the plasmonic effect diminished rapidly. The distance-dependent plasmon-induced phosphorescence enhancement mechanism was further investigated by time-resolved photoluminescence measurements. Our results reveal the correlation between the amplification efficiency and plasmonic band, spatial factor, and spectral characteristics of the purely organic phosphor, which may provide an insightful picture to extend the utility of organic phosphors by using surface plasmon-induced emission enhancement scheme.

  14. Adsorption of Different Fractions of Organic Matter on the Surface of Metal Oxide

    KAUST Repository

    Zaouri, Noor A

    2013-05-18

    The adsorption of different fractions of organic matter on the surface of Al2O3 and ZrO2 were investigated. The aim was to study the affinity of these fractions on the surface of metal oxide and the effect of several factors. Batch adsorption experiments were conducted with Low molecular weight oxygenated compounds. These chemical compound have been chosen to investigate:1) the aliphatic and aromatic structurer;2)contribution of hydroxyl group and; 3) the number of carboxyl group. HPLC and IC analysis used for determent the concentration of these chemical in the working solution. ATR-FTIR used to distinguish the type of coordination structure with the surface of metal oxide. The results fitted with Langmuir equation. The results showed that the chemical structure and the type and number of attached functional have an impact on the adsorption. Which it was proved via ATR-FTIR where the result showed that each chemical have different coordination structure on the surface of ZrO2 and Al2O3. Different fractions and sources of NOM were used (hydrophobic fraction of Suwannee and Colorado River, biopolymers extracted for the exuded of 2 species of algae, and low molecular acids that do not adsorb in XAD-8 resin). Results showed that these different fractions have different affinity with the surface of Al2O3 and ZrO2. These adsorption behaviors were varying according to the difference in the component of each NOM. Biopolymers showed significant adsorption at acidic pH. These biopolymers are mainly comprised of polysaccharides and this result proved that polysaccharide adsorb on the surface of ZrO2 more than Al2O3.

  15. Chemical bonding of hydrogen molecules to transition metal complexes

    International Nuclear Information System (INIS)

    Kubas, G.J.

    1990-01-01

    The complex W(CO) 3 (PR 3 ) 2 (H 2 ) (CO = carbonyl; PR 3 = organophosphine) was prepared and was found to be a stable crystalline solid under ambient conditions from which the hydrogen can be reversibly removed in vacuum or under an inert atmosphere. The weakly bonded H 2 exchanges easily with D 2 . This complex represents the first stable compound containing intermolecular interaction of a sigma-bond (H-H) with a metal. The primary interaction is reported to be donation of electron density from the H 2 bonding electron pair to a vacant metal d-orbital. A series of complexes of molybdenum of the type Mo(CO)(H 2 )(R 2 PCH 2 CH 2 PR 2 ) 2 were prepared by varying the organophosphine substitutent to demonstrate that it is possible to bond either dihydrogen or dihydride by adjusting the electron-donating properties of the co-ligands. Results of infrared and NMR spectroscopic studies are reported. 20 refs., 5 fig

  16. Chemical bonding of hydrogen molecules to transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kubas, G.J.

    1990-01-01

    The complex W(CO){sub 3}(PR{sub 3}){sub 2}(H{sub 2}) (CO = carbonyl; PR{sub 3} = organophosphine) was prepared and was found to be a stable crystalline solid under ambient conditions from which the hydrogen can be reversibly removed in vacuum or under an inert atmosphere. The weakly bonded H{sub 2} exchanges easily with D{sub 2}. This complex represents the first stable compound containing intermolecular interaction of a sigma-bond (H-H) with a metal. The primary interaction is reported to be donation of electron density from the H{sub 2} bonding electron pair to a vacant metal d-orbital. A series of complexes of molybdenum of the type Mo(CO)(H{sub 2})(R{sub 2}PCH{sub 2}CH{sub 2}PR{sub 2}){sub 2} were prepared by varying the organophosphine substitutent to demonstrate that it is possible to bond either dihydrogen or dihydride by adjusting the electron-donating properties of the co-ligands. Results of infrared and NMR spectroscopic studies are reported. 20 refs., 5 fig.

  17. Metal coatings prepared by organometallic chemical vapour deposition (OMCVD)

    Energy Technology Data Exchange (ETDEWEB)

    Wochnowski, Joern; Heck, Juergen [Institute of Inorganic and Applied Chemistry, Hamburg (Germany); Goellnitz, Thimo [Institute of Inorganic and Applied Chemistry, Hamburg (Germany); Institute of Applied Physics, University of Hamburg (Germany); Hoffmann, Germar; Wiesendanger, Roland [Institute of Applied Physics, University of Hamburg (Germany)

    2008-07-01

    In microtechnology, the coating of temperature-sensitive substrates with high melting-point materials is challenging. The use of volatile organometallic compounds can be an answer to solve this ambitious task. We developed an experimental set-up for the deposition of elements, oxides, and functional composites in glass hollowware by means of OMCVD. With the first experimental set-up, the thermally induced decomposition of numerous elementorganic and metallorganic precursors has been tested for the deposition of catalytic or optic materials. Here, we present experimental data of the thermal deposition of different metals as tungsten on a glass surface. We used Atomic Force Microscopy as one standard analytical surface method to obtain structural and morphological information of the deposited metal layers. We discuss the preparation and the analytics of the prepared surfaces. With the objective to bring the deposition temperature of W(CO){sub 6} further down to room temperature, we developed a new photolytic OMCVD set-up. We demonstrate and discuss the realization of our experimental setup.

  18. Chemical form of metals in traditional medicines underlines potential toxicity in cell cultures.

    Science.gov (United States)

    Wu, Qin; Lu, Yuan-Fu; Shi, Jing-Zhen; Liang, Shi-Xia; Shi, Jin-Shan; Liu, Jie

    2011-04-12

    Mercury (Hg) and arsenic (As) are frequently found in traditional medicines as sulfides, such as cinnabar (HgS) and realgar (As(4)S(4)). There is a general perception that any medicinal use of such metal-containing remedies is unacceptable. An opposing opinion is that different chemical forms of arsenic and mercury have different toxic potentials. To clarify this question, cinnabar, realgar, and cinnabar- and realgar-containing traditional medicine An-Gong-Niu-HuangWan (AGNH), were compared to well-known mercurials (HgS, HgCl(2) and MeHg) and arsenicals (As(2)S(2), As(2)O(3), NaAsO(2), and Na(2)HAsO(4)) for their cytotoxicity in human and rodent cell lines. Cultured cells derived from target organs such as brain (HAPI) and liver (Hep3B, HepG2 and TRL1215) were treated with chemicals for 48 h and cytotoxicity was determined by the MTS assay. MeHg was most toxic with LC(50) of 4-20μM, followed by NaAsO(2) (LC(50), 25-250 μM) and HgCl(2) (LC(50,) 50-100 μM), Na(2)HAsO(4)(LC(50), 60-400μM), As(2)O(3)(LC(50), 30-900 μM), and As(2)S(2) (LC(50), 100-500 μM). In comparison, the LC(50) of realgar ranged from 250 to1500 μM; whereas cinnabar or HgS were approximately 20,000 μM and the toxicity of AGNH was in the range of 1500-8000 μM. Approximately 5000-fold differences exist between MeHg and HgS, and over 10-fold differences exist between NaAsO(2) and As(4)S(4). Chemical forms of metals are important factor in determining their toxicity in traditional medicines, both cinnabar and realgar are much less toxic than well-known mercurial and arsenicals. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  19. Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) for highly selective separations

    Energy Technology Data Exchange (ETDEWEB)

    Yaghi, Omar M

    2012-09-17

    Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) have been investigated for the realization as separation media with high selectivity. These structures are held together with strong bonds, making them architecturally, chemically, and thermally stable. Therefore, employing well designed building units, it is possible to discover promising materials for gas and vapor separation. This grant was focused on the study of MOFs and ZIFs with these specific objectives: (i) to develop a strategy for producing MOFs and ZIFs that combine high surface areas with active sites for their use in gas adsorption and separation of small organic compounds, (ii) to introduce active sites in the framework by a post-synthetic modification and metalation of MOFs and ZIFs, and (iii) to design and synthesize MOFs with extremely high surface areas and large pore volumes to accommodate large amounts of guest molecules. By the systematic study, this effort demonstrated how to introduce active functional groups in the frameworks, and this is also the origin of a new strategy, which is termed isoreticular functionalization and metalation. However, a large pore volume is still a prerequisite feature. One of the solutions to overcome this challenge is an isoreticular expansion of a MOF's structure. With triangular organic linker and square building units, we demonstrated that MOF-399 has a unit cell volume 17 times larger than that of the first reported material isoreticular to it, and it has the highest porosity (94%) and lowest density (0.126 g cm-3) of any MOF reported to date. MOFs are not just low density materials; the guest-free form of MOF-210 demonstrates an ultrahigh porosity, whose BET surface area was estimated to be 6240 m2 g-1 by N2 adsorption measurements.

  20. Design, synthesis and characterization of metal organic frameworks

    KAUST Repository

    Eddaoudi, Mohamed

    2015-12-03

    A molecular building block composition can include a metal ion component; and a ligand component including a core including at least one functional group associated with the metal ion component and the core.

  1. Organic chemical degradation by remote study of the redox conditions

    Science.gov (United States)

    Fernandez, P. M.; Revil, A.; Binley, A. M.; Bloem, E.; French, H. K.

    2014-12-01

    Monitoring the natural (and enhanced) degradation of organic contaminants is essential for managing groundwater quality in many parts of the world. Contaminated sites often have limited access, hence non-intrusive methods for studying redox processes, which drive the degradation of organic compounds, are required. One example is the degradation of de-icing chemicals (glycols and organic salts) released to the soil near airport runways during winter. This issue has been broadly studied at Oslo airport, Gardermoen, Norway using intrusive and non-intrusive methods. Here, we report on laboratory experiments that aim to study the potential of using a self-potential, DCresistivity, and time-domain induced polarization for geochemical characterization of the degradation of Propylene Glycol (PG). PG is completely miscible in water, does not adsorb to soil particles and does not contribute to the electrical conductivity of the soil water. When the contaminant is in the unsaturated zone near the water table, the oxygen is quickly consumed and the gas exchange with the surface is insufficient to ensure aerobic degradation, which is faster than anaerobic degradation. Since biodegradation of PG is highly oxygen demanding, anaerobic pockets can exist causing iron and manganese reduction. It is hypothesised that nitrate would boost the degradation rate under such conditions. In our experiment, we study PG degradation in a sand tank. We provide the system with an electron highway to bridge zones with different redox potential. This geo-battery system is characterized by self-potential, resistivity and induced polarization anomalies. An example of preliminary results with self-potential at two different times of the experiment can be seen in the illustration. These will be supplemented with more direct information on the redox chemistry: in-situ water sampling, pH, redox potential and electrical conductivity measurements. In parallel, a series of batch experiments have been

  2. Electronic self-organization in layered transition metal dichalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Ritschel, Tobias

    2015-10-30

    The interplay between different self-organized electronically ordered states and their relation to unconventional electronic properties like superconductivity constitutes one of the most exciting challenges of modern condensed matter physics. In the present thesis this issue is thoroughly investigated for the prototypical layered material 1T-TaS{sub 2} both experimentally and theoretically. At first the static charge density wave order in 1T-TaS{sub 2} is investigated as a function of pressure and temperature by means of X-ray diffraction. These data indeed reveal that the superconductivity in this material coexists with an inhomogeneous charge density wave on a macroscopic scale in real space. This result is fundamentally different from a previously proposed separation of superconducting and insulating regions in real space. Furthermore, the X-ray diffraction data uncover the important role of interlayer correlations in 1T-TaS{sub 2}. Based on the detailed insights into the charge density wave structure obtained by the X-ray diffraction experiments, density functional theory models are deduced in order to describe the electronic structure of 1T-TaS{sub 2} in the second part of this thesis. As opposed to most previous studies, these calculations take the three-dimensional character of the charge density wave into account. Indeed the electronic structure calculations uncover complex orbital textures, which are interwoven with the charge density wave order and cause dramatic differences in the electronic structure depending on the alignment of the orbitals between neighboring layers. Furthermore, it is demonstrated that these orbital-mediated effects provide a route to drive semiconductor-to-metal transitions with technologically pertinent gaps and on ultrafast timescales. These results are particularly relevant for the ongoing development of novel, miniaturized and ultrafast devices based on layered transition metal dichalcogenides. The discovery of orbital textures

  3. Destruction of chemical warfare agent simulants by air and moisture stable metal NHC complexes.

    Science.gov (United States)

    Weetman, Catherine; Notman, Stuart; Arnold, Polly L

    2018-02-20

    The cooperative effect of both NHC and metal centre has been found to destroy chemical warfare agent (CWA) simulants. Choice of both the metal and NHC is key to these transformations as simple, monodentate N-heterocyclic carbenes in combination with silver or vanadium can promote stoichiometric destruction, whilst bidentate, aryloxide-tethered NHC complexes of silver and alkali metals promote breakdown under mild heating. Iron-NHC complexes generated in situ are competent catalysts for the destruction of each of the three targetted CWA simulants.

  4. Physical-chemical purification of power metal optics for increasing its service life

    Science.gov (United States)

    Filin, S. A.; Rogalin, V. E.; Kaplunov, I. A.; Zingerman, K. M.

    2017-12-01

    In order to increase the resource of power metal optics, the features of the choice of solvents for its physical and chemical cleaning are investigated. During cleaning, on the contaminated surface there remain visually observed white film of alkali and alkaline earth metal salts, insoluble by this class of solvents, and iridescent bands from the interaction of hydrocarbons with metal, and this degrades optical properties and reduces the life of mirrors. It is demonstrated that, with the use of solvents, it is necessary to inhibit the interaction of hydrocarbons with mirrors by the stabilization of solvents or by selection of cleaning regimes.

  5. Bilayer–metal assisted chemical etching of silicon microwire arrays for photovoltaic applications

    Directory of Open Access Journals (Sweden)

    R. W. Wu

    2016-02-01

    Full Text Available Silicon microwires with lateral dimension from 5 μm to 20 μm and depth as long as 20 μm are prepared by bilayer metal assisted chemical etching (MaCE. A bilayer metal configuration (Metal 1 / Metal 2 was applied to assist etching of Si where metal 1 acts as direct catalyst and metal 2 provides mechanical support. Different metal types were investigated to figure out the influence of metal catalyst on morphology of etched silicon. We find that silicon microwires with vertical side wall are produced when we use Ag/Au bilayer, while cone–like and porous microwires formed when Pt/Au is applied. The different micro-/nano-structures in as-etched silicon are demonstrated to be due to the discrepancy of work function of metal catalyst relative to Si. Further, we constructed a silicon microwire arrays solar cells in a radial p–n junction configurations in a screen printed aluminum paste p–doping process.

  6. Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding

    International Nuclear Information System (INIS)

    Lichtenberger, D.L.

    1991-10-01

    The formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies has been developed into a single equation which unifies the treatment of covalent bonds, ionic bonds, and partially ionic bonds. This relationship has been used to clarify the fundamental thermodynamic information relating to metal-hydrogen, metal-alkyl, and metal-metal bond energies. We have been able to obtain a direct observation and measurement of the stabilization energy provided by the agostic interaction of the C-H bond with the metal. The ionization energies have also been used to correlate the rates of carbonyl substitution reactions of (η 5 -C 5 H 4 X)Rh(CO) 2 complexes, and to reveal the electronic factors that control the stability of the transition state. The extent that the electronic features of these bonding interactions transfer to other chemical systems is being investigated in terms of the principle of additivity of ligand electronic effects. Specific examples under study include metal- phosphines, metal-halides, and metallocenes. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C 60 molecule, buckminsterfullerene, and its interaction with a metal surface. The high-resolution valence ionizations in the gas phase reveal the high symmetry of the molecule, and studies of thin films of C 60 reveal weak intermolecular interactions. Scanning tunneling and atomic force microscopy reveal the arrangement of spherical molecules on gold substrates, with significant delocalization of charge from the metal surface. 21 refs

  7. Photoreactivity of Metal-Organic Frameworks in Aqueous Solutions: Metal Dependence of Reactive Oxygen Species Production.

    Science.gov (United States)

    Liu, Kai; Gao, Yanxin; Liu, Jing; Wen, Yifan; Zhao, Yingcan; Zhang, Kunyang; Yu, Gang

    2016-04-05

    Promising applications of metal-organic frameworks (MOFs) in various fields have raised concern over their environmental fate and safety upon inevitable discharge into aqueous environments. Currently, no information regarding the transformation processes of MOFs is available. Due to the presence of repetitive π-bond structure and semiconductive property, photochemical transformations are an important fate process that affects the performance of MOFs in practical applications. In the current study, the generation of reactive oxygen species (ROS) in isoreticular MIL-53s was studied. Scavengers were employed to probe the production of (1)O2, O2(•-), and •OH, respectively. In general, MIL-53(Cr) and MIL-53(Fe) are dominated by type I and II photosensitization reactions, respectively, and MIL-53(Al) appears to be less photoreactive. The generation of ROS in MIL-53(Fe) may be underestimated due to dismutation. Further investigation of MIL-53(Fe) encapsulated diclofenac transformation revealed that diclofenac can be easily transformed by MIL-53(Fe) generated ROS. However, the cytotoxicity results implied that the ROS generated from MIL-53s have little effect on the viability of the human hepatocyte (HepG2) cell line. These results suggest that the photogeneration of ROS by MOFs may be metal-node dependent, and the application of MIL-53s as drug carriers needs to be carefully considered due to their high photoreactivity.

  8. Porous, rigid metal(III)-carboxylate metal-organic frameworks for the delivery of nitric oxide

    Science.gov (United States)

    Eubank, Jarrod F.; Wheatley, Paul S.; Lebars, Gaëlle; McKinlay, Alistair C.; Leclerc, Hervé; Horcajada, Patricia; Daturi, Marco; Vimont, Alexandre; Morris, Russell E.; Serre, Christian

    2014-12-01

    The room temperature sorption properties of the biological gas nitric oxide (NO) have been investigated on the highly porous and rigid iron or chromium carboxylate based metal-organic frameworks Material Institut Lavoisier (MIL)-100(Fe or Cr) and MIL-127(Fe). In all cases, a significant amount of NO is chemisorbed at 298 K with a loading capacity that depends both on the nature of the metal cation, the structure and the presence of additional iron(II) Lewis acid sites. In a second step, the release of NO triggered by wet nitrogen gas has been studied by chemiluminescence and indicates that only a partial release of NO occurs as well as a prolonged delivery at the biological level. Finally, an in situ infrared spectroscopy study confirms not only the coordination of NO over the Lewis acid sites and the stronger binding of NO on the additional iron(II) sites, providing further insights over the partial release of NO only in the presence of water at room temperature.

  9. Porous, rigid metal(III-carboxylate metal-organic frameworks for the delivery of nitric oxide

    Directory of Open Access Journals (Sweden)

    Jarrod F. Eubank

    2014-12-01

    Full Text Available The room temperature sorption properties of the biological gas nitric oxide (NO have been investigated on the highly porous and rigid iron or chromium carboxylate based metal-organic frameworks Material Institut Lavoisier (MIL-100(Fe or Cr and MIL-127(Fe. In all cases, a significant amount of NO is chemisorbed at 298 K with a loading capacity that depends both on the nature of the metal cation, the structure and the presence of additional iron(II Lewis acid sites. In a second step, the release of NO triggered by wet nitrogen gas has been studied by chemiluminescence and indicates that only a partial release of NO occurs as well as a prolonged delivery at the biological level. Finally, an in situ infrared spectroscopy study confirms not only the coordination of NO over the Lewis acid sites and the stronger binding of NO on the additional iron(II sites, providing further insights over the partial release of NO only in the presence of water at room temperature.

  10. The Application of Metal Oxide Nanomaterials for Chemical Sensor Development

    Science.gov (United States)

    Xu, Jennifer C.; Hunter, Gary W.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.

    2007-01-01

    NASA Glenn Research Center (GRC) has been developing miniature chemical sensors for a variety of applications including fire detection, emissions monitoring, fuel leak detection, and environmental monitoring. Smart Lick and Stick sensor technology which integrates a sensor array, electronics, telemetry, and power into one microsystem are being developed. These microsystems require low power consumption for long-term aerospace applications. One approach to decreasing power consumption is the use of nanotechnology. Nanocrystalline tin oxide (SnO2) carbon monoxide (CO) sensors developed previously by this group have been successfully used for fire detection and emissions monitoring. This presentation will briefly review the overall NASA GRC chemical sensor program and discuss our further effort in nanotechnology applications. New carbon dioxide (CO2) sensing material using doped nanocrystalline SnO2 will be discussed. Nanocrystalline SnO2 coated solid electrolyte CO2 sensors and SnO2 nanorod and nanofiber hydrogen (H2) sensors operated at reduced or room temperatures will also be discussed.

  11. Artificial intelligence/fuzzy logic method for analysis of combined signals from heavy metal chemical sensors

    Energy Technology Data Exchange (ETDEWEB)

    Turek, M. [Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Campus Juelich, Juelich (Germany); Institute of Bio- and Nanosystems (IBN), Research Centre Juelich GmbH, Juelich (Germany); Heiden, W.; Riesen, A. [Bonn-Rhein-Sieg University of Applied Sciences, Sankt Augustin (Germany); Chhabda, T.A. [Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Campus Juelich, Juelich (Germany); Schubert, J.; Zander, W. [Institute of Bio- and Nanosystems (IBN), Research Centre Juelich GmbH, Juelich (Germany); Krueger, P. [Institute of Biochemistry and Molecular Biology, RWTH Aachen, Aachen (Germany); Keusgen, M. [Institute for Pharmaceutical Chemistry, Philipps-University Marburg, Marburg (Germany); Schoening, M.J. [Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Campus Juelich, Juelich (Germany); Institute of Bio- and Nanosystems (IBN), Research Centre Juelich GmbH, Juelich (Germany)], E-mail: m.j.schoening@fz-juelich.de

    2009-10-30

    The cross-sensitivity of chemical sensors for several metal ions resembles in a way the overlapping sensitivity of some biological sensors, like the optical colour receptors of human retinal cone cells. While it is difficult to assign crisp classification values to measurands based on complex overlapping sensory signals, fuzzy logic offers a possibility to mathematically model such systems. Current work goes into the direction of mixed heavy metal solutions and the combination of fuzzy logic with heavy metal-sensitive, silicon-based chemical sensors for training scenarios of arbitrary sensor/probe combinations in terms of an electronic tongue. Heavy metals play an important role in environmental analysis. As trace elements as well as water impurities released from industrial processes they occur in the environment. In this work, the development of a new fuzzy logic method based on potentiometric measurements performed with three different miniaturised chalcogenide glass sensors in different heavy metal solutions will be presented. The critical validation of the developed fuzzy logic program will be demonstrated by means of measurements in unknown single- and multi-component heavy metal solutions. Limitations of this program and a comparison between calculated and expected values in terms of analyte composition and heavy metal ion concentration will be shown and discussed.

  12. Organ- and species-specific accumulation of metals in two land snail species (Gastropoda, Pulmonata)

    International Nuclear Information System (INIS)

    Boshoff, Magdalena; Jordaens, Kurt; Backeljau, Thierry; Lettens, Suzanna; Tack, Filip; Vandecasteele, Bart; De Jonge, Maarten; Bervoets, Lieven

    2013-01-01

    In order to evaluate the usefulness of terrestrial gastropods as bioindicators there is a need for studies that simultaneously compare (1) concentrations of metals in reference and polluted plots, (2) species within the same polluted habitat, (3) metal accumulation patterns in different organs and (4) metal accumulation patterns in relation to soil physicochemical properties. This study aims to assess metal accumulation patterns in two land snail species. Instead of analyzing an organism as a whole, investigating the partitioning of metals in different organs can provide information on the actual toxicological relevant fractions. Therefore, concentrations of Ag, Cd, Cr, Cu, Ni and Zn were examined in five different organs of Cepaea nemoralis, as well as in the foot and the body of Succinea putris. Snails were sampled at four polluted dredged sediment disposal localities and three adjacent less polluted reference plots situated along waterways in Flanders, Belgium. Due to the small size and problematic dissection of S. putris only the concentrations in the foot of both species could be compared. For this reason only, C. nemoralis can be described as a better bioindicator species that allows a far more detailed analysis of organ metal accumulation. This study showed that organs other than the digestive gland may be involved in the immobilization and detoxification of metals. Furthermore, pH, soil fractionation (clay %, silt %, sand %) and organic matter, correlate with metal accumulation in organs. However, most often the soil metal concentrations did not correlate with the concentrations found in snail organs. Metal concentrations in organs of both species (1) differed among polluted plots but rarely between polluted and reference plots within a locality, (2) were organ-specific (digestive gland > foot > albumen gland = spermoviduct = ovotestis), (3) were species-specific and (4) depended on the metal type (high Cd and Cu concentrations were observed in the

  13. Organ- and species-specific accumulation of metals in two land snail species (Gastropoda, Pulmonata)

    Energy Technology Data Exchange (ETDEWEB)

    Boshoff, Magdalena, E-mail: magdalena.boshoff@ua.ac.be [University of Antwerp, Systemic Physiological and Ecotoxicological Research, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Jordaens, Kurt [Royal Museum for Central Africa (JEMU), Leuvensesteenweg 13, B-3080 Tervuren (Belgium); University of Antwerp, Evolutionary Ecology Group, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Backeljau, Thierry [University of Antwerp, Evolutionary Ecology Group, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Royal Belgian Institute of Natural Sciences (JEMU), Vautierstraat 29, B-1000 Brussels (Belgium); Lettens, Suzanna [Research Institute for Nature and Forest (INBO), Kliniekstraat 25, B-1070 Brussels (Belgium); Tack, Filip [Ghent University, Laboratory of Analytical Chemistry and Applied Ecochemistry, Coupure Links 265, B-9000 Ghent (Belgium); Vandecasteele, Bart [Institute for Agricultural and Fisheries Research (ILVO), Burg van Gansberghelaan 109, B-9820 Merelbeke (Belgium); De Jonge, Maarten; Bervoets, Lieven [University of Antwerp, Systemic Physiological and Ecotoxicological Research, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2013-04-01

    In order to evaluate the usefulness of terrestrial gastropods as bioindicators there is a need for studies that simultaneously compare (1) concentrations of metals in reference and polluted plots, (2) species within the same polluted habitat, (3) metal accumulation patterns in different organs and (4) metal accumulation patterns in relation to soil physicochemical properties. This study aims to assess metal accumulation patterns in two land snail species. Instead of analyzing an organism as a whole, investigating the partitioning of metals in different organs can provide information on the actual toxicological relevant fractions. Therefore, concentrations of Ag, Cd, Cr, Cu, Ni and Zn were examined in five different organs of Cepaea nemoralis, as well as in the foot and the body of Succinea putris. Snails were sampled at four polluted dredged sediment disposal localities and three adjacent less polluted reference plots situated along waterways in Flanders, Belgium. Due to the small size and problematic dissection of S. putris only the concentrations in the foot of both species could be compared. For this reason only, C. nemoralis can be described as a better bioindicator species that allows a far more detailed analysis of organ metal accumulation. This study showed that organs other than the digestive gland may be involved in the immobilization and detoxification of metals. Furthermore, pH, soil fractionation (clay %, silt %, sand %) and organic matter, correlate with metal accumulation in organs. However, most often the soil metal concentrations did not correlate with the concentrations found in snail organs. Metal concentrations in organs of both species (1) differed among polluted plots but rarely between polluted and reference plots within a locality, (2) were organ-specific (digestive gland > foot > albumen gland = spermoviduct = ovotestis), (3) were species-specific and (4) depended on the metal type (high Cd and Cu concentrations were observed in the

  14. CONCENTRATION OF TOXIC INGREDIENTS (HAEVY METALS AND AROMATIC HYDROCARBONS IN ORGANS AND TISSUES OF HYDROBIONTS IN CENTRAL CASPIAN DISTRICT

    Directory of Open Access Journals (Sweden)

    S. A. Guseinova

    2013-01-01

    Full Text Available Abstract. Aim. Incorporation rate of heavy metals in fish is an important informative integrant index that allows estimating the impact of water pollution and fodder hydrobiont contamination on fish organisms. Unlike other contaminating anthropogenic factors of the Caspian Sea, metals are always present in the sea interacting with fish organisms many thousands times as the result of biological and chemical circuit.Methods. We analysed the grade of concentration of heavy metals in tissues and organs of hydrobionts under the program “the Central Caspian District of the Caspian Sea marine environment”. The procedure for determining metals consisted in determination of concentration of heavy metals in accordance with the methodology recommendations of atomic absorption analysis of Dagestan 52.24.28-86, with the help of atomic absorption spectrophotometer Hitachi 180-50.Results. The results after analysis of concentration of heavy metals in the tissues and organs of fish caught in the Central Caspian Sea marine environment are compared with the average annual estimation. The results obtained on the analysis of concentration of hydrocarbons in hydrobionts selected in the Central Caspian District of the Caspian Sea marine environment are within the long-term annual average data that are typical of the Northern and Middle Caspian Sea.Main conclusions. The results obtained help to form scientific foundation of ecological regulation that takes into account some ecosystems’ anthropogenic stability. Concentration of pollutants (heavy metals and hydrocarbons in hydrobiont tissues characterizes the ecological situation on the whole of the Caspian Sea due to hydrobionts’ large-scale migrations. The analysis of the dynamics of the pollutant concentration in tissues reflects the situation created in the drilling areas; it will help forecast and avert the negative impact of hydrocarbon production on the Caspian Sea ecosystem.

  15. Secondary organic aerosols. Chemical aging, hygroscopicity, and cloud droplet activation

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, Angela

    2011-07-06

    Atmospheric aerosols have an important impact on the radiation balance, and thus, on the climate of the Earth. Aerosol particles scatter and absorb incoming solar and terrestrial radiation. Apart from this direct effect, aerosol particles act as cloud condensation nuclei (CCN), thereby greatly influencing the microphysics of clouds. Secondary organic aerosols (SOA) are an important fraction of the total aerosol mass. In many environments these organic compounds are mainly products of the oxidation of biogenic volatile organic compounds (VOC). In this study the hygroscopic growth and CCN activation of biogenic SOA were investigated which was formed by the oxidation of VOC with O{sub 3} and photochemically formed OH radicals under low NO{sub x} conditions. For this purpose, a complex mixture of VOC emitted by boreal tree species as gas-phase precursors was used in the Juelich Plant Atmosphere Chamber (JPAC). In long-term studies in the atmosphere simulation chamber SAPHIR {alpha}-pinene or a defined mixture of {alpha}-pinene, {beta}-pinene, limonene, ocimene, {delta}-3-carene served as precursors. Initial precursor concentrations between 40 and 1000 ppbC were investigated. The observed SOA particles were slightly hygroscopic with an average hygroscopicity parameter {kappa}(CCN) = 0.10 {+-} 0.02 and {kappa}(90%RH) = 0.05 {+-} 0.01. Closure between hygroscopic growth and CCN activation data could be achieved allowing either surface tension reduction, limited solubility, or non-ideality of the solution in the droplet. The SOA solutions in equilibrium with RH <95% are possible highly non-ideal. Therefore the organic-water interaction were investigated by applying the UNIFAC model. Calculations for surrogate compounds exhibited the same strong concentration (i.e. RH) dependence of {kappa} at sub-saturation. The growth curves could be fitted and CCN activation predicted by assuming a binary mixture of water and one hypothetical organic compound. The occurrence of

  16. Self-aligned metallization on organic semiconductor through 3D dual-layer thermal nanoimprint

    Science.gov (United States)

    Jung, Y.; Cheng, X.

    2014-09-01

    High-resolution patterning of metal structures on organic semiconductors is important to the realization of high-performance organic transistors for organic integrated circuit applications. The traditional shadow mask technique has a limited resolution, precluding sub-micron metal structures on organic semiconductors. Thus organic transistors cannot benefit from scaling into the deep sub-micron region to improve their dc and ac performances. In this work, we report an efficient multiple-level metallization on poly (3-hexylthiophene) (P3HT) with a deep sub-micron lateral gap. By using a 3D nanoimprint mold in a dual-layer thermal nanoimprint process, we achieved self-aligned two-level metallization on P3HT. The 3D dual-layer thermal nanoimprint enables the first metal patterns to have suspending side-wings that can clearly define a distance from the second metal patterns. Isotropic and anisotropic side-wing structures can be fabricated through two different schemes. The process based on isotropic side-wings achieves a lateral-gap in the order of 100 nm (scheme 1). A gap of 60 nm can be achieved from the process with anisotropic side-wings (scheme 2). Because of the capability of nanoscale metal patterning on organic semiconductors with high overlay accuracy, this self-aligned metallization technique can be utilized to fabricate high-performance organic metal semiconductor field-effect transistor.

  17. phisco-chemical studies concerning naturally occuring radiocuclides and heavy metal concentrations in groundwater

    International Nuclear Information System (INIS)

    Abd Allah, A.A.A.

    2011-01-01

    The present work is a comprehensive of drinking water quality from various rural regions of Egypt. People are living in these rural regions have a problem of scarcely water resources. They mainly depend on groundwater resources for drinking. These water resources may be contaminated with both naturally and/or industrial pollutants unexpected. In this study, several groundwater samples are obtained from certain regions in Egypt; physical, chemical and radiological parameters are examined. Then, compared to the standard limits values of the world health organization. A new modified ion exchange resin was prepared in our laboratory with a high efficiency factor which may be used for reducing the heavy metals that are being found in groundwater samples. The removal of heavy metals such as, Pb (II), Co (II) and Mn (II) ions was carried out by the modified ion exchange resin using Batch sorption experiments. The optimum condition of the removal efficiency was conducted under different parameters such as; effect of ph, initial ion concentrations, weight loaded and contact time to determine the optimum conditions for the resin function. Kinetic studies are performed using first and second order kinetic equations. The sorption kinetic experiments are found to be agreeing well with the second order kinetic equation. The particle diffusion model was also studied. three isotherm equations are applied for sorption of the investigated elements at equilibrium are well described by the Freundlich isotherm equation indicating that sorption process of those elements are applied with heterogeneous adsorption reaction. Dubinin and Radushkevich (D-R) isotherm equation is also applied. The free energy of the adsorption process is also given in the range of the ion exchange reaction.

  18. Chemical and plant tests to assess the viability of amendments to reduce metal availability in mine soils and tailings.

    Science.gov (United States)

    Rodríguez, Luis; Gómez, Rocío; Sánchez, Virtudes; Alonso-Azcárate, Jacinto

    2016-04-01

    The goal of this research was to assess the potential of several industrial wastes to immobilise metals in two polluted soils deriving from an old Pb/Zn mine. Two different approaches were used to assess the performance of different amendments: a chemical one, using extraction by ethylenediaminetetraacetic acid (EDTA), and a biological one, using Lupinus albus as a bio-indicator. Four amendments were used: inorganic sugar production waste (named 'sugar foam', SF), sludge from a drinking water treatment sludge (DWS), organic waste from olive mill waste (OMW) and paper mill sludge (PMS). Amendment to soil ratios ranged from 0.1 to 0.3 (w/w). All the amendments were capable of significantly decreasing (p mine soils as it led to a decrease in the availability and toxicity of metals and, thus, facilitated the growth of a vegetation layer.

  19. Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

    Science.gov (United States)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

    Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

  20. Biological and chemical characterization of metal bioavailability in sediments from Lake Roosevelt, Columbia River, Washington, USA

    Science.gov (United States)

    Besser, J.M.; Brumbaugh, W.G.; Ivey, C.D.; Ingersoll, C.G.; Moran, P.W.

    2008-01-01

    We studied the bioavailability and toxicity of copper, zinc, arsenic, cadmium, and lead in sediments from Lake Roosevelt (LR), a reservoir on the Columbia River in Washington, USA that receives inputs of metals from an upstream smelter facility. We characterized chronic sediment toxicity, metal bioaccumulation, and metal concentrations in sediment and pore water from eight study sites: one site upstream in the Columbia River, six sites in the reservoir, and a reference site in an uncontaminated tributary. Total recoverable metal concentrations in LR sediments generally decreased from upstream to downstream in the study area, but sediments from two sites in the reservoir had metal concentrations much lower than adjacent reservoir sites and similar to the reference site, apparently due to erosion of uncontaminated bank soils. Concentrations of acid-volatile sulfide in LR sediments were too low to provide strong controls on metal bioavailability, and selective sediment extractions indicated that metals in most LR sediments were primarily associated with iron and manganese oxides. Oligochaetes (Lumbriculus variegatus) accumulated greatest concentrations of copper from the river sediment, and greatest concentrations of arsenic, cadmium, and lead from reservoir sediments. Chronic toxic effects on amphipods (Hyalella azteca; reduced survival) and midge larvae (Chironomus dilutus; reduced growth) in whole-sediment exposures were generally consistent with predictions of metal toxicity based on empirical and equilibrium partitioning-based sediment quality guidelines. Elevated metal concentrations in pore waters of some LR sediments suggested that metals released from iron and manganese oxides under anoxic conditions contributed to metal bioaccumulation and toxicity. Results of both chemical and biological assays indicate that metals in sediments from both riverine and reservoir habitats of Lake Roosevelt are available to benthic invertebrates. These findings will be used as

  1. Humidity Detection Using Metal Organic Framework Coated on QCM

    KAUST Repository

    Kosuru, Lakshmoji

    2016-06-28

    Quartz crystal microbalance (QCM) coated with poly-4-vinylpyridine (PVP) and metal organic framework HKUST-1 are investigated and compared for humidity sensing. Drop casting method is employed to coat the PVP and HKUST-1 solutions onto the surface of a quartz crystal microbalance. The resonance frequencies of these sensors with varying relative humidity (RH) from 22% RH to 69% RH are measured using impedance analysis method. The sensitivity, humidity hysteresis, response, and recovery times of these sensors are studied. The sensitivities of uncoated, PVP, and HKUST-1 coated QCM sensors are 7 Hz, 48 Hz, and 720 Hz, respectively, in the range of 22% RH–69% RH. The extraction of desorption rate and adsorption energy associated with the adsorption and desorption of water molecules on these surfaces reveals that HKUST-1 has better sensing properties than PVP and uncoated QCM sensors. In this work, the HKUST-1 coated QCM is shown to be a promising material for moisture detection.

  2. Metal-organic frameworks for lithium ion batteries and supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang, E-mail: hdeng@whu.edu.cn

    2015-03-15

    Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100–1000 m{sup 2} g{sup −1}) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m{sup 2} g{sup −1}), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefit from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs. - Graphical abstract: MOFs with large surface area and high porosity can offer more reaction sites and charge carriers diffusion path. Thus MOFs are used as cathode, anode, electrolyte, matrix and precursor materials for lithium ion battery, and also as electrode and precursor materials for supercapacitors. - Highlights: • MOFs have potential in electrochemical area due to their high porosity and diversity. • We summarized and compared works on MOFs for lithium ion battery and supercapacitor. • We pointed out critical challenges and provided possible solutions for future study.

  3. 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.

  4. 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).

  5. Humidity Detection Using Metal Organic Framework Coated on QCM

    Directory of Open Access Journals (Sweden)

    Lakshmoji Kosuru

    2016-01-01

    Full Text Available Quartz crystal microbalance (QCM coated with poly-4-vinylpyridine (PVP and metal organic framework HKUST-1 are investigated and compared for humidity sensing. Drop casting method is employed to coat the PVP and HKUST-1 solutions onto the surface of a quartz crystal microbalance. The resonance frequencies of these sensors with varying relative humidity (RH from 22% RH to 69% RH are measured using impedance analysis method. The sensitivity, humidity hysteresis, response, and recovery times of these sensors are studied. The sensitivities of uncoated, PVP, and HKUST-1 coated QCM sensors are 7 Hz, 48 Hz, and 720 Hz, respectively, in the range of 22% RH–69% RH. The extraction of desorption rate and adsorption energy associated with the adsorption and desorption of water molecules on these surfaces reveals that HKUST-1 has better sensing properties than PVP and uncoated QCM sensors. In this work, the HKUST-1 coated QCM is shown to be a promising material for moisture detection.

  6. Metallization on FDM Parts Using the Chemical Deposition Technique

    Directory of Open Access Journals (Sweden)

    Azhar Equbal

    2014-08-01

    Full Text Available Metallization of ABS (acrylonitrile-butadiene-styrene parts has been studied on flat part surfaces. These parts are fabricated on an FDM (fused deposition modeling machine using the layer-wise deposition principle using ABS as a part material. Electroless copper deposition on ABS parts was performed using two different surface preparation processes, namely ABS parts prepared using chromic acid for etching and ABS parts prepared using a solution mixture of sulphuric acid and hydrogen peroxide (H2SO4/H2O2 for etching. After surface preparations using these routes, copper (Cu is deposited electrolessly using four different acidic baths. The acidic baths used are 5 wt% CuSO4 (copper sulfate with 15 wt% of individual acids, namely HF (hydrofluoric acid, H2SO4 (sulphuric acid, H3PO4 (phosphoric acid and CH3COOH (acetic acid. Cu deposition under different acidic baths used for both the routes is presented and compared based on their electrical performance, scanning electron microscopy (SEM and energy dispersive X-ray spectrometry (EDS. The result shows that chromic acid etched samples show better electrical performance and Cu deposition in comparison to samples etched via H2SO4/H2O2.

  7. Novel Chemical Process for Producing Chrome Coated Metal

    Directory of Open Access Journals (Sweden)

    Christopher Pelar

    2018-01-01

    Full Text Available This work demonstrates that a version of the Reduction Expansion Synthesis (RES process, Cr-RES, can create a micron scale Cr coating on an iron wire. The process involves three steps. I. A paste consisting of a physical mix of urea, chrome nitrate or chrome oxide, and water is prepared. II. An iron wire is coated by dipping. III. The coated, and dried, wire is heated to ~800 °C for 10 min in a tube furnace under a slow flow of nitrogen gas. The processed wires were then polished and characterized, primarily with scanning electron microscopy (SEM. SEM indicates the chrome layer is uneven, but only on the scale of a fraction of a micron. The evidence of porosity is ambiguous. Elemental mapping using SEM electron microprobe that confirmed the process led to the formation of a chrome metal layer, with no evidence of alloy formation. Additionally, it was found that thickness of the final Cr layer correlated with the thickness of the precursor layer that was applied prior to the heating step. Potentially, this technique could replace electrolytic processing, a process that generates carcinogenic hexavalent chrome, but further study and development is needed.

  8. Novel Chemical Process for Producing Chrome Coated Metal.

    Science.gov (United States)

    Pelar, Christopher; Greenaway, Karima; Zea, Hugo; Wu, Chun-Hsien; Luhrs, Claudia C; Phillips, Jonathan

    2018-01-05

    This work demonstrates that a version of the Reduction Expansion Synthesis (RES) process, Cr-RES, can create a micron scale Cr coating on an iron wire. The process involves three steps. I. A paste consisting of a physical mix of urea, chrome nitrate or chrome oxide, and water is prepared. II. An iron wire is coated by dipping. III. The coated, and dried, wire is heated to ~800 °C for 10 min in a tube furnace under a slow flow of nitrogen gas. The processed wires were then polished and characterized, primarily with scanning electron microscopy (SEM). SEM indicates the chrome layer is uneven, but only on the scale of a fraction of a micron. The evidence of porosity is ambiguous. Elemental mapping using SEM electron microprobe that confirmed the process led to the formation of a chrome metal layer, with no evidence of alloy formation. Additionally, it was found that thickness of the final Cr layer correlated with the thickness of the precursor layer that was applied prior to the heating step. Potentially, this technique could replace electrolytic processing, a process that generates carcinogenic hexavalent chrome, but further study and development is needed.

  9. Fabrication of metal organic framework materials using a layer-by-layer spin coating approach

    KAUST Repository

    Eddaoudi, Mohamed

    2016-03-17

    Embodiments describe a method of depositing an MOF, including depositing a metal solution onto a substrate, spinning the substrate sufficient to spread the metal solution, depositing an organic ligand solution onto the substrate and spinning the substrate sufficient to spread the organic ligand solution and form a MOF layer.

  10. Engineering chiral porous metal-organic frameworks for enantioselective adsorption and separation

    Science.gov (United States)

    Peng, Yongwu; Gong, Tengfei; Zhang, Kang; Lin, Xiaochao; Liu, Yan; Jiang, Jianwen; Cui, Yong

    2014-07-01

    The separation of racemic molecules is of substantial significance not only for basic science but also for technical applications, such as fine chemicals and drug development. Here we report two isostructural chiral metal-organic frameworks decorated with chiral dihydroxy or -methoxy auxiliares from enantiopure tetracarboxylate-bridging ligands of 1,1‧-biphenol and a manganese carboxylate chain. The framework bearing dihydroxy groups functions as a solid-state host capable of adsorbing and separating mixtures of a range of chiral aromatic and aliphatic amines, with high enantioselectivity. The host material can be readily recycled and reused without any apparent loss of performance. The utility of the present adsorption separation is demonstrated in the large-scale resolution of racemic 1-phenylethylamine. Control experiments and molecular simulations suggest that the chiral recognition and separation are attributed to the different orientations and specific binding energies of the enantiomers in the microenvironment of the framework.

  11. Gas storage in porous metal-organic frameworks for clean energy applications.

    Science.gov (United States)

    Ma, Shengqian; Zhou, Hong-Cai

    2010-01-07

    Depletion of fossil oil deposits and the escalating threat of global warming have put clean energy research, which includes the search for clean energy carriers such as hydrogen and methane as well as the reduction of carbon dioxide emissions, on the urgent agenda. A significant technical challenge has been recognized as the development of a viable method to efficiently trap hydrogen, methane and carbon dioxide gas molecules in a confined space for various applications. This issue can be addressed by employing highly porous materials as storage media, and porous metal-organic frameworks (MOFs) which have exceptionally high surface areas as well as chemically-tunable structures are playing an unusual role in this respect. In this feature article we provide an overview of the current status of clean energy applications of porous MOFs, including hydrogen storage, methane storage and carbon dioxide capture.

  12. A Simple Approach to Enhance the Water Stability of a Metal-Organic Framework.

    Science.gov (United States)

    Shih, Yung-Han; Kuo, Yu-Ching; Lirio, Stephen; Wang, Kun-Yun; Lin, Chia-Her; Huang, Hsi-Ya

    2017-01-01

    A facile method to improve the feasibility of water-unstable metal-organic frameworks in an aqueous environment has been developed that involves imbedding in a polymer monolith. The effect of compartment type during polymerization plays a significant role in maintaining the crystalline structure and thermal stability of the MOFs, which was confirmed by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA), respectively. The MOF-polymer composite prepared in a narrow compartment (column, ID 0.8 mm) has better thermal and chemical stability than that prepared in a broad compartment (vial, ID 7 mm). The developed MOF-polymer composite was applied as an adsorbent in solid-phase microextraction of nine non-steroidal anti-inflammatory drugs (NSAIDs) and could be used for extraction more than 30 times, demonstrating that the proposed approach has potential for industrial applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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.

  14. Chemistry of Metal-organic Frameworks Monitored by Advanced X-ray Diffraction and Scattering Techniques.

    Science.gov (United States)

    Mazaj, Matjaž; Kaučič, Venčeslav; Zabukovec Logar, Nataša

    2016-01-01

    The research on metal-organic frameworks (MOFs) experienced rapid progress in recent years due to their structure diversity and wide range of application opportunities. Continuous progress of X-ray and neutron diffraction methods enables more and more detailed insight into MOF's structural features and significantly contributes to the understanding of their chemistry. Improved instrumentation and data processing in high-resolution X-ray diffraction methods enables the determination of new complex MOF crystal structures in powdered form. By the use of neutron diffraction techniques, a lot of knowledge about the interaction of guest molecules with crystalline framework has been gained in the past few years. Moreover, in-situ time-resolved studies by various diffraction and scattering techniques provided comprehensive information about crystallization kinetics, crystal growth mechanism and structural dynamics triggered by external physical or chemical stimuli. The review emphasizes most relevant advanced structural studies of MOFs based on powder X-ray and neutron scattering.

  15. Experimental comparison of chiral metal-organic framework used as stationary phase in chromatography.

    Science.gov (United States)

    Xie, Sheng-Ming; Zhang, Mei; Fei, Zhi-Xin; Yuan, Li-Ming

    2014-10-10

    Chiral metal-organic frameworks (MOFs) are a new class of multifunctional material, which possess diverse structures and unusual properties such as high surface area, uniform and permanent cavities, as well as good chemical and thermal stability. Their chiral functionality makes them attractive as novel enantioselective adsorbents and stationary phases in separation science. In this paper, the experimental comparison of a chiral MOF [In₃O(obb)₃(HCO₂)(H₂O)] solvent used as a stationary phase was investigated in gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). The potential relationship between the structure and components of chiral MOFs with their chiral recognition ability and selectivity are presented. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. HEAVY METALS IN ORGANS AND TISSUES OF STERLET (ACIPENSER RUTHENUS L. IN THE DNIEPER-BUG ESTUARY

    Directory of Open Access Journals (Sweden)

    Yu. Sytnik

    2016-09-01

    Full Text Available Purpose.To iInvestigate and analyze the peculiarities of the accumulation of heavy metals (Cu, Fe, Zn, Cd, Pb, Co, Ni and Mn in the organs (muscles, gills, liver, kidneys, fins, intestine and tissues of sterlet (Acipenser ruthenus Linnaeus, 1758 for detecting the patterns of their accumulation and predicting the effect of their toxicological load on the organism of sturgeons as well as for evaluating the polymetallic load on this species in the Dnieper-Bug estuary. Methodology. The material for the research was represented by 3+ – 4+ sterlet caught in the spring of 2016 in the Dnieper-Bug estuary. Organs and tissue samples were homogenized and then burned in a mixture of concentrated nitric (HNO3 and hydrochloric acid (HCl. The determination of heavy metals in organs and tissues of fish were performed by flame atomic absorption spectroscopy using an atomic absorption spectrophotometer AAS-3 and AAS-3N company "Carl Zeiss" (Jena, Germany. Findings. The distribution of heavy metals in organs and tissues of sterlet (Acipenser ruthenus L. of the Dnieper-Bug estuary in the spring of 2016 was characterized by heterogeneity and depended on their physico-chemical properties and functional characteristics of organs and tissues of the investigated fish. The highest quantities copper, zinc and iron are accumulated liver, while manganese and cobalt in gills. Toxic metals (lead and cadmium are more concentrated in gills, skin and liver. The maximum contents in the tissues and organs of sterlet were observed for iron and zinc, while the minimals ones — for cadmium and cobalt. Originality. The paper describes the actual data on the contents and peculiarities of heavy metal accumulation in the body of sterlet inhabiting the Dnieper-Bug estuary. Practical value. The paper contains the newest information on the accumulation and content of heavy metals in organs and tissues of sterlet in the Dnieper-Bug estuary. The results of the work will be used for future

  17. Role of noble metal nanoparticles in DNA base damage and catalysis: a radiation chemical investigation

    International Nuclear Information System (INIS)

    Sharma, Geeta K.

    2011-01-01

    In the emerging field of nanoscience and nanotechnology, tremendous focus has been made by researcher to explore the applications of nanomaterials for human welfare by converting the findings into technology. Some of the examples have been the use of nanoparticles in the field of opto-electronic, fuel cells, medicine and catalysis. These wide applications and significance lies in the fact that nanoparticles possess unique physical and chemical properties very different from their bulk precursors. Numerous methods for the synthesis of noble nanoparticles with tunable shape and size have been reported in literature. The goal of our group is to use different methods of synthesis of noble metal nanoparticles (Au, Ag, Pt and Pd) and test their protective/damaging role towards DNA base damage induced by ionizing radiation (Au and Ag) and to test the catalytic activity of nanoparticles (Pt and Pd) in certain known organic synthesis/electron transfer reactions. Using radiation chemical techniques such as pulse radiolysis and steady state radiolysis complemented by the product analysis using HPLC/LC-MS, a detailed mechanism for the formation of transient species, kinetics leading to the formation of stable end products is studied in the DNA base damage induced by ionizing radiation in presence and absence of Au and Ag nanoparticles. Unraveling the complex interaction between catalysts and reactants under operando conditions is a key step towards gaining fundamental insight in catalysis. The catalytic activity of Pt and Pd nanoparticles in electron transfer and Suzuki coupling reactions has been determined. Investigations are currently underway to gain insight into the interaction between catalysts and reactants using time resolved spectroscopic measurements. These studies will be detailed during the presentation. (author)

  18. Heavy metals and arsenic fixation into freshwater organic matter under Gammarus pulex L. influence.

    Science.gov (United States)

    Schaller, Joerg; Mkandawire, Martin; Gert Dudel, E

    2010-07-01

    Organic sediments are a main sink for metal pollutants in aquatic systems. However, factors that make sediments a sink of metals and metalloids are still not clear. Consequently, we investigate the role of invertebrate shredders (Gammarus pulex L.) on quality of metal and arsenic fixation into organic partitions of sediment in the course of litter decay with laboratory microcosm experiments. During the decomposition of leaf litter, G. pulex significantly facilitated the development of small particles of organic matter. The capacity of metal fixation was significantly higher in smaller particles than leaf litter and litter residuals. Thus, G. pulex enhanced metal fixation into the organic partition of sediments by virtue of increasing the amount smaller particles in the aquatic system. Furthermore, invertebrates have a significant effect on formation of dissolved organic matter and remobilization of cobalt, molybdenum and cesium, but no significant effect on remobilization of all other measured elements. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  19. Creating a Discovery Platform for Confined-Space Chemistry and Materials: Metal-Organic Frameworks.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Greathouse, Jeffery A.; Simmons, Blake

    2008-09-01

    Metal organic frameworks (MOF) are a recently discovered class of nanoporous, defect-free crystalline materials that enable rational design and exploration of porous materials at the molecular level. MOFs have tunable monolithic pore sizes and cavity environments due to their crystalline nature, yielding properties exceeding those of most other porous materials. These include: the lowest known density (91% free space); highest surface area; tunable photoluminescence; selective molecular adsorption; and methane sorption rivaling gas cylinders. These properties are achieved by coupling inorganic metal complexes such as ZnO4 with tunable organic ligands that serve as struts, allowing facile manipulation of pore size and surface area through reactant selection. MOFs thus provide a discovery platform for generating both new understanding of chemistry in confined spaces and novel sensors and devices based on their unique properties. At the outset of this project in FY06, virtually nothing was known about how to couple MOFs to substrates and the science of MOF properties and how to tune them was in its infancy. An integrated approach was needed to establish the required knowledge base for nanoscale design and develop methodologies integrate MOFs with other materials. This report summarizes the key accomplishments of this project, which include creation of a new class of radiation detection materials based on MOFs, luminescent MOFs for chemical detection, use of MOFs as templates to create nanoparticles of hydrogen storage materials, MOF coatings for stress-based chemical detection using microcantilevers, and "flexible" force fields that account for structural changes in MOFs that occur upon molecular adsorption/desorption. Eight journal articles, twenty presentations at scientific conferences, and two patent applications resulted from the work. The project created a basis for continuing development of MOFs for many Sandia applications and succeeded in securing $2.75 M in

  20. Exposure to chemicals and metals and risk of amyotrophic lateral sclerosis: a systematic review

    NARCIS (Netherlands)

    Sutedja, N.A.; Veldink, J.H.; Fischer, K.; Kromhout, H.; Heederik, D.J.J.; Huisman, M.H.B.; Wokke, J.H.J.; van den Berg, L.H.

    2009-01-01

    Environmental exposure to chemicals and metals may contribute to the risk of sporadic amyotrophic lateral sclerosis (ALS). Two systematic reviews of the literature on these topics performed according to the well-established MOOSE guidelines are presented. Literature cited in MEDLINE, EMBASE, CINAHL,

  1. A comprehensive study of high metallicity giant extragalactic H II regions: chemical abundances

    OpenAIRE

    Castellanos, Marcelo; Díaz, Angeles I.

    2002-01-01

    This is an electronic version of an article published in Revista Mexicana de Astronomía y Astrofísica. Castellanos, Marcelo, and Angeles I. Díaz. A comprehensive study of high-metallicity giant extragalactic H II regions: chemical abundances. Revista Mexicana de Astronomía y Astrofísica 12 (2002): 238-239

  2. Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

    KAUST Repository

    Shaikh Ali, Anaam

    2015-07-06

    Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

  3. Influence of dissimilatory metal reduction on fate of organic and metal contaminants in the subsurface

    Science.gov (United States)

    Lovley, Derek R.; Anderson, Robert T.

    Dissimilatory Fe(III)-reducing microorganisms have the ability to destroy organic contaminants under anaerobic conditions by oxidizing them to carbon dioxide. Some Fe(III)-reducing microorganisms can also reductively dechlorinate chlorinated contaminants. Fe(III)-reducing microorganisms can reduce a variety of contaminant metals and convert them from soluble forms to forms that are likely to be immobilized in the subsurface. Studies in petroleum-contaminated aquifers have demonstrated that Fe(III)-reducing microorganisms can be effective agents in removing aromatic hydrocarbons from groundwater under anaerobic conditions. Laboratory studies have demonstrated the potential for Fe(III)-reducing microorganisms to remove uranium from contaminated groundwaters. The activity of Fe(III)-reducing microorganisms can be stimulated in several ways to enhance organic contaminant oxidation and metal reduction. Molecular analyses in both field and laboratory studies have demonstrated that microorganisms of the genus Geobacter become dominant members of the microbial community when Fe(III)-reducing conditions develop as the result of organic contamination, or when Fe(III) reduction is artificially stimulated. These results suggest that further understanding of the ecophysiology of Geobacter species would aid in better prediction of the natural attenuation of organic contaminants under anaerobic conditions and in the design of strategies for the bioremediation of subsurface metal contamination. Des micro-organismes simulant la réduction du fer ont la capacité de détruire des polluants organiques dans des conditions anérobies en les oxydant en dioxyde de carbone. Certains micro-organismes réducteurs de fer peuvent aussi dé-chlorer par réduction des polluants chlorés. Des micro-organismes réducteurs de fer peuvent réduire tout un ensemble de métaux polluants et les faire passer de formes solubles à des formes qui sont susceptibles d'être immobilisées dans le milieu

  4. Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

    Science.gov (United States)

    Kang, Tae-Woon; Noh, Yong-Jin; Yun, Jin-Mun; Yang, Si-Young; Yang, Yong-Eon; Lee, Hae-Seong; Na, Seok-In

    2015-06-01

    This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs.

  5. Influence of chemical pretreatment of hard metal substrates for diamond deposition

    International Nuclear Information System (INIS)

    Buck, V.; Kluwe, H.; Schmiler, B.; Deuerler, F.

    2001-01-01

    Diamond coated cutting tools are of increasing importance in the fields of high speed cutting, dry machining or machining of special materials such as metal-matrix-composites. A well known problem is the poor adhesion of diamond films on hard metals due to the Co- or Ni-binder that catalyzes the formation of graphite. Several methods - such as the application of intermediate layers or mechanical or chemical pretreatment of the hard metal substrate - have been developed to overcome this effect. Usually chemical pretreatment is used in order to reduce the concentration of binder phase on the surface that is to be coated. Surprisingly pretreatment with agents such as Murakami's solution result in improved adhesion and nucleation of diamond films while the concentration of the binder phase on the surface is enhanced. This 'contradiction' can be explained by proving that the surface is converted into a very thin oxide/hydroxide film. (author)

  6. Chemical and microstructural analyses for heavy metals removal from water media by ceramic membrane filtration.

    Science.gov (United States)

    Ali, Asmaa; Ahmed, Abdelkader; Gad, Ali

    2017-01-01

    This study aims to investigate the ability of low cost ceramic membrane filtration in removing three common heavy metals namely; Pb 2+ , Cu 2+ , and Cd 2+ from water media. The work includes manufacturing ceramic membranes with dimensions of 15 by 15 cm and 2 cm thickness. The membranes were made from low cost materials of local clay mixed with different sawdust percentages of 0.5%, 2.0%, and 5.0%. The used clay was characterized by X-ray diffraction (XRD) and X-ray fluorescence analysis. Aqueous solutions of heavy metals were prepared in the laboratory and filtered through the ceramic membranes. The influence of the main parameters such as pH, initial driving pressure head, and concentration of heavy metals on their removal efficiency by ceramic membranes was investigated. Water samples were collected before and after the filtration process and their heavy metal concentrations were determined by chemical analysis. Moreover, a microstructural analysis using scanning electronic microscope (SEM) was performed on ceramic membranes before and after the filtration process. The chemical analysis results showed high removal efficiency up to 99% for the concerned heavy metals. SEM images approved these results by showing adsorbed metal ions on sides of the internal pores of the ceramic membranes.

  7. Removal of heavy metals from aqueous phases using chemically modified waste Lyocell fiber

    Energy Technology Data Exchange (ETDEWEB)

    Bediako, John Kwame; Wei, Wei; Kim, Sok; Yun, Yeoung-Sang, E-mail: ysyun@jbnu.ac.kr

    2015-12-15

    Highlights: • Waste Lyocell fiber was chemically modified into cellulose xanthate. • The sorbent showed high affinity for Pb(II), Cd(II) and Cu(II) ions. • The sorbent also showed strong Cu(II) selectivity in Pb(II)–Cd(II)–Cu(II) ternary metal solutions. - Abstract: In this study, an outstanding performance of chemically modified waste Lyocell for heavy metals treatment is reported. The sorbent, which was prepared by a simple and concise method, was able to bind heavy metals such as Pb(II), Cu(II) and Cd(II), with very high efficiencies. The binding mechanisms were studied through adsorption and standard characterization tests such as scanning electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analyses. Adsorption kinetics was very fast and attained equilibrium within 5 min in all metals studied. The maximum single metal uptakes were 531.29 ± 0.28 mg/g, 505.64 ± 0.21 mg/g, and 123.08 ± 0.26 mg/g for Pb(II), Cd(II) and Cu(II), respectively. In ternary metal systems, Cu(II) selectivity was observed and the underlying factors were discussed. The sorbent by its nature, could be very effective in treating large volumes of wastewater with the contact of very little amount.

  8. Physico-Chemical Evolution of Organic Aerosol from Wildfire Emissions

    Science.gov (United States)

    Croteau, P.; Jathar, S.; Akherati, A.; Galang, A.; Tarun, S.; Onasch, T. B.; Lewane, L.; Herndon, S. C.; Roscioli, J. R.; Yacovitch, T. I.; Fortner, E.; Xu, W.; Daube, C.; Knighton, W. B.; Werden, B.; Wood, E.

    2017-12-01

    Wildfires are the largest combustion-related source of carbonaceous emissions to the atmosphere; these include direct emissions of black carbon (BC), primary organic aerosol (POA) and semi-volatile, intermediate-volatility, and volatile organic compounds (SVOCs, IVOCs, and VOCs). However, there are large uncertainties surrounding the evolution of these carbonaceous emissions as they are physically and chemically transformed in the atmosphere. To understand these transformations, we performed sixteen experiments using an environmental chamber to simulate day- and night-time chemistry of gas- and aerosol-phase emissions from 6 different fuels at the Fire Laboratory in Missoula, MT. Across the test matrix, the experiments simulated 2 to 8 hours of equivalent day-time aging (with the hydroxyl radical and ozone) or several hours of night-time aging (with the nitrate radical). Aging resulted in an average organic aerosol (OA) mass enhancement of 28% although the full range of OA mass enhancements varied between -10% and 254%. These enhancement findings were consistent with chamber and flow reactor experiments performed at the Fire Laboratory in 2010 and 2012 but, similar to previous studies, offered no evidence to link the OA mass enhancement to fuel type or oxidant exposure. Experiments simulating night-time aging resulted in an average OA mass enhancement of 10% and subsequent day-time aging resulted in a decrease in OA mass of 8%. While small, for the first time, these experiments highlighted the continuous nature of the OA evolution as the wildfire smoke cycled through night- and day-time processes. Ongoing work is focussed on (i) quantifying bulk compositional changes in OA, (ii) comparing the near-field aging simulated in this work with far-field aging simulated during the same campaign (via a mini chamber and flow tube) and (iii) integrating wildfire smoke aging datasets over the past decade to examine the relationship between OA mass enhancement ratios, modified

  9. Isolation and chemical characterization of dissolved and colloidal organic matter

    Science.gov (United States)

    Aiken, G.; Leenheer, J.

    1993-01-01

    Commonly used techniques for the concentration and isolation of organic matter from water, such as preparative chromatography, ultrafiltration and reverse osmosis, and the methods used to analyze the organic matter obtained by these methods are reviewed. The development of methods to obtain organic matter that is associated with fractions of the dissolved organic carbon other than humic substances, such as organic bases, hydrophilic organic acids and colloidal organic matter are discussed. Methods specifically used to study dissolved organic nitrogen and dissolved organic phosphorous are also discussed. -from Authors

  10. The role of organic matter on metal toxicity and bio-availability.

    Science.gov (United States)

    Calace, Nicoletta; Petronio, Bianca Maria

    2004-01-01

    A short review concerning the role of organic matter on metal toxicity and bio-availability in aqueous systems is carried out. The complexity of the issue derives both from the high number of natural and anthropogenic organic compounds and from the variability of their structures. In fact, the binding capacity and affinity is dependent on the number and type of ligands, on their position in the structures, on the ligand/metal ratio. It is also necessary to develop analytical protocol in order to carry out speciation studies of organic carbon and of metals bound to organic compounds, and at the same time to characterise the nature of the complexes.

  11. Metal organic frameworks for enzyme immobilization in biofuel cells

    Science.gov (United States)

    Bodell, JaDee

    Interest in biofuel cells has been rapidly expanding as an ever-growing segment of the population gains access to electronic devices. The largest areas of growth for new populations using electronic devices are often in communities without electrical infrastructure. This lack of infrastructure in remote environments is one of the key driving factors behind the development of biofuel cells. Biofuel cells employ biological catalysts such as enzymes to catalyze oxidation and reduction reactions of select fuels to generate power. There are several benefits to using enzymes to catalyze reactions as compared to traditional fuel cells which use metal catalysts. First, enzymes are able to catalyze reactions at or near room temperature, whereas traditional metal catalysts are only efficient at very high temperatures. Second, biofuel cells can operate under mild pH conditions which is important for the eventual design of safe, commercially viable devices. Also, biofuel cells allow for implantable and flexible technologies. Finally, enzymes exhibit high selectivity and can be combined to fully oxidize or reduce the fuel which can generate several electrons from a single molecule of fuel, increasing the overall device efficiency. One of the main challenges which persist in biofuel cells is the instability of enzymes over time which tend to denature after hours or days. For a viable commercial biofuel cell to be produced, the stability of enzymes must be extended to months or years. Enzymes have been shown to have improved stability after being immobilized. The focus of this research was to find a metal organic framework (MOF) structure which could successfully immobilize enzymes while still allowing for electron transport to occur between the catalytic center of the enzyme and the electrode surface within a biofuel cell for power generation. Four MOF structures were successfully synthesized and were subsequently tested to determine the MOF's ability to immobilize the following

  12. The Role of Electronic Excitations on Chemical Reaction Dynamics at Metal, Semiconductor and Nanoparticle Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tully, John C. [Yale Univ., New Haven, CT (United States)

    2017-06-10

    Chemical reactions are often facilitated and steered when carried out on solid surfaces, essential for applications such as heterogeneous catalysis, solar energy conversion, corrosion, materials processing, and many others. A critical factor that can determine the rates and pathways of chemical reactions at surfaces is the efficiency and specificity of energy transfer; how fast does energy move around and where does it go? For reactions on insulator surfaces energy transfer generally moves in and out of vibrations of the adsorbed molecule and the underlying substrate. By contrast, on metal surfaces, metallic nanoparticles and semiconductors, another pathway for energy flow opens up, excitation and de-excitation of electrons. This so-called “nonadiabatic” mechanism often dominates the transfer of energy and can directly impact the course of a chemical reaction. Conventional computational methods such as molecular dynamics simulation do not account for this nonadiabatic behavior. The current DOE-BES funded project has focused on developing the underlying theoretical foundation and the computational methodology for the prediction of nonadiabatic chemical reaction dynamics at surfaces. The research has successfully opened up new methodology and new applications for molecular simulation. In particular, over the last three years, the “Electronic Friction” theory, pioneered by the PI, has now been developed into a stable and accurate computational method that is sufficiently practical to allow first principles “on-the-fly” simulation of chemical reaction dynamics at metal surfaces.

  13. Assessing determinants of maternal blood concentrations for persistent organic pollutants and metals in the eastern and western Canadian Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Curren, Meredith S., E-mail: meredith.curren@hc-sc.gc.ca [Chemicals Surveillance Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, 269 Laurier Avenue West, Ottawa, Ontario (Canada); Liang, Chun Lei, E-mail: chun.lei.liang@hc-sc.gc.ca [Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Columbine Driveway, Tunney' s Pasture, Ottawa, Ontario (Canada); Davis, Karelyn, E-mail: karelyn.davis@hc-sc.gc.ca [Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Columbine Driveway, Tunney' s Pasture, Ottawa, Ontario (Canada); Kandola, Kami, E-mail: Kami_Kandola@gov.nt.ca [Government of the Northwest Territories, Yellowknife, Northwest Territories (Canada); Brewster, Janet, E-mail: jbrewster@gov.nu.ca [Government of Nunavut, Iqaluit, Nunavut (Canada); Potyrala, Mary, E-mail: mary_potyrala@yahoo.ca [Government of Nunavut, Iqaluit, Nunavut (Canada); Chan, Hing Man, E-mail: laurie.chan@uottawa.ca [Center for Advanced Research in Environmental Genomics, University of Ottawa, 20 Marie-Curie, Ottawa, Ontario (Canada)

    2015-09-15

    Aboriginal peoples in the Canadian Arctic are exposed to persistent organic pollutants (POPs) and metals mainly through their consumption of a traditional diet of wildlife items. Recent studies indicate that many human chemical levels have decreased in the north, likely due to a combination of reduced global chemical emissions, dietary shifts, and risk mitigation efforts by local health authorities. Body burdens for chemicals in mothers can be further offset by breastfeeding, parity, and other maternal characteristics. We have assessed the impact of several dietary and maternal covariates following a decade of awareness of the contaminant issue in northern Canada, by performing multiple stepwise linear regression analyses from blood concentrations and demographic variables for 176 mothers recruited from Nunavut and the Northwest Territories during the period 2005–2007. A significant aboriginal group effect was observed for the modeled chemicals, except for lead and cadmium, after adjusting for covariates. Further, blood concentrations for POPs and metals were significantly associated with at least one covariate of older age, fewer months spent breastfeeding, more frequent eating of traditional foods, or smoking during pregnancy. Cadmium had the highest explained variance (72.5%) from just two significant covariates (current smoking status and parity). Although Inuit participants from the Northwest Territories consumed more traditional foods in general, Inuit participants from coastal communities in Nunavut continued to demonstrate higher adjusted blood concentrations for POPs and metals examined here. While this is due in part to a higher prevalence of marine mammals in the eastern Arctic diet, it is possible that other aboriginal group effects unrelated to diet may also contribute to elevated chemical body burdens in Canadian Arctic populations. - Highlights: • In 2005–07, younger age was related to lower levels of chemicals in northern Canada. • Eastern

  14. Assessing determinants of maternal blood concentrations for persistent organic pollutants and metals in the eastern and western Canadian Arctic

    International Nuclear Information System (INIS)

    Curren, Meredith S.; Liang, Chun Lei; Davis, Karelyn; Kandola, Kami; Brewster, Janet; Potyrala, Mary; Chan, Hing Man

    2015-01-01

    Aboriginal peoples in the Canadian Arctic are exposed to persistent organic pollutants (POPs) and metals mainly through their consumption of a traditional diet of wildlife items. Recent studies indicate that many human chemical levels have decreased in the north, likely due to a combination of reduced global chemical emissions, dietary shifts, and risk mitigation efforts by local health authorities. Body burdens for chemicals in mothers can be further offset by breastfeeding, parity, and other maternal characteristics. We have assessed the impact of several dietary and maternal covariates following a decade of awareness of the contaminant issue in northern Canada, by performing multiple stepwise linear regression analyses from blood concentrations and demographic variables for 176 mothers recruited from Nunavut and the Northwest Territories during the period 2005–2007. A significant aboriginal group effect was observed for the modeled chemicals, except for lead and cadmium, after adjusting for covariates. Further, blood concentrations for POPs and metals were significantly associated with at least one covariate of older age, fewer months spent breastfeeding, more frequent eating of traditional foods, or smoking during pregnancy. Cadmium had the highest explained variance (72.5%) from just two significant covariates (current smoking status and parity). Although Inuit participants from the Northwest Territories consumed more traditional foods in general, Inuit participants from coastal communities in Nunavut continued to demonstrate higher adjusted blood concentrations for POPs and metals examined here. While this is due in part to a higher prevalence of marine mammals in the eastern Arctic diet, it is possible that other aboriginal group effects unrelated to diet may also contribute to elevated chemical body burdens in Canadian Arctic populations. - Highlights: • In 2005–07, younger age was related to lower levels of chemicals in northern Canada. • Eastern

  15. 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

  16. Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite.

    Science.gov (United States)

    Ambrosi, Adriano; Chua, Chun Kiang; Khezri, Bahareh; Sofer, Zdeněk; Webster, Richard D; Pumera, Martin

    2012-08-07

    Graphene-related materials are in the forefront of nanomaterial research. One of the most common ways to prepare graphenes is to oxidize graphite (natural or synthetic) to graphite oxide and exfoliate it to graphene oxide with consequent chemical reduction to chemically reduced graphene. Here, we show that both natural and synthetic graphite contain a large amount of metallic impurities that persist in the samples of graphite oxide after the oxidative treatment, and chemically reduced graphene after the chemical reduction. We demonstrate that, despite a substantial elimination during the oxidative treatment of graphite samples, a significant amount of impurities associated to the chemically reduced graphene materials still remain and alter their electrochemical properties dramatically. We propose a method for the purification of graphenes based on thermal treatment at 1,000 °C in chlorine atmosphere to reduce the effect of such impurities on the electrochemical properties. Our findings have important implications on the whole field of graphene research.

  17. Surface stress and large-scale self-organization at organic-metal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian

    2009-01-22

    The role of elastic interactions, particularly for the self-organized formation of periodically faceted interfaces, was investigated in this thesis for archetype organic-metal interfaces. The cantilever bending technique was applied to study the change of surface stress upon formation of the interface between 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and Ag(111). The main focus of this work was on the investigation of the formation of the long-range ordered, self-organized faceted PTCDA/Ag(10 8 7) interface. Reciprocal space maps of this interface were recorded both by spot profile analysis low energy electron diffraction (SPA-LEED) and low energy electron microscopy (LEEM) in selected area LEED mode. Complementary to the reciprocal data, also microscopic real-space LEEM data were used to characterize the morphology of this interface. Six different facet faces ((111), (532), (743), (954), (13 9 5), and (542)) were observed for the preparation path of molecular adsorption on the substrate kept at 550 K. Facet-sensitive dark-field LEEM localized these facets to grow in homogeneous areas of microscopic extensions. The temperature-dependence of the interface formation was studied in a range between 418 K and 612 K in order to learn more about the kinetics of the process. Additional steeper facets of 27 inclination with respect to the (111) surface were observed in the low temperature regime. Furthermore, using facet-sensitive dark-field LEEM, spatial and size distributions of specific facets were studied for the different temperatures. Moreover, the facet dimensions were statistically analyzed. The total island size of the facets follows an exponential distribution, indicating a random growth mode in absence of any mutual facet interactions. While the length distribution of the facets also follows an exponential distribution, the width distribution is peaked, reflecting the high degree of lateral order. This anisotropy is temperature-dependent and occurs

  18. Ultrafast rotation in an amphidynamic crystalline metal organic framework.

    Science.gov (United States)

    Vogelsberg, Cortnie S; Uribe-Romo, Fernando J; Lipton, Andrew S; Yang, Song; Houk, K N; Brown, Stuart; Garcia-Garibay, Miguel A

    2017-12-26

    Amphidynamic crystals are an emergent class of condensed phase matter designed with a combination of lattice-forming elements linked to components that display engineered dynamics in the solid state. Here, we address the design of a crystalline array of molecular rotors with inertial diffusional rotation at the nanoscale, characterized by the absence of steric or electronic barriers. We solved this challenge with 1,4-bicyclo[2.2.2]octane dicarboxylic acid (BODCA)-MOF, a metal-organic framework (MOF) built with a high-symmetry bicyclo[2.2.2]octane dicarboxylate linker in a Zn 4 O cubic lattice. Using spin-lattice relaxation 1 H solid-state NMR at 29.49 and 13.87 MHz in the temperature range of 2.3-80 K, we showed that internal rotation occurs in a potential with energy barriers of 0.185 kcal mol -1 These results were confirmed with 2 H solid-state NMR line-shape analysis and spin-lattice relaxation at 76.78 MHz obtained between 6 and 298 K, which, combined with molecular dynamics simulations, indicate that inertial diffusional rotation is characterized by a broad range of angular displacements with no residence time at any given site. The ambient temperature rotation of the bicyclo[2.2.2]octane (BCO) group in BODCA-MOF constitutes an example where engineered rotational dynamics in the solid state are as fast as they would be in a high-density gas or in a low-density liquid phase.

  19. Ultrafast rotation in an amphidynamic crystalline metal organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Vogelsberg, Cortnie S.; Uribe-Romo, Fernando J.; Lipton, Andrew S.; Yang, Song; Houk, K. N.; Brown, Stuart; Garcia-Garibay, Miguel A.

    2017-12-11

    Amphidynamic crystals are an emergent class of condensed phase matter designed with a combination of lattice-forming elements linked to components that display engineered dynamics in the solid state. Here, we address the design of a crystalline array of molecular rotors with inertial diffusional rotation at the nanoscale, characterized by the absence of steric or electronic barriers. We solved this challenge with 1,4-bicyclo[2.2.2]octane dicarboxylic acid (BODCA)-MOF, a metal-organic framework (MOF) built with a high-symmetry bicyclo[2.2.2]octane dicarboxylate linker in a Zn4O cubic lattice. Using spin-lattice relaxation 1H solid-state NMR at 29.49 and 13.87 MHz in the temperature range of 2.3–80 K, we showed that internal rotation occurs in a potential with energy barriers of 0.185 kcal mol-1. These results were confirmed with 2H solid-state NMR line-shape analysis and spin-lattice relaxation at 76.78 MHz obtained between 6 and 298 K, which, combined with molecular dynamics simulations, indicate that inertial diffusional rotation is characterized by a broad range of angular displacements with no residence time at any given site. The ambient temperature rotation of the bicyclo[2.2.2]octane (BCO) group in BODCA-MOF constitutes an example where engineered rotational dynamics in the solid state are as fast as they would be in a high-density gas or in a low-density liquid phase.

  20. Unconventional metal organic frameworks: porous cross-linked phosphonates.

    Science.gov (United States)

    Clearfield, Abraham

    2008-11-28

    The past decade has witnessed an exponential growth of metal organic framework compounds (MOFs). The defining character of these compounds is their porosity. However, in many cases no effort was made to show evidence that a stable porous structure has been achieved and that the pores may be accessed. In the present paper we describe recent work on porous pillared zirconium diphosphonates, and the newer and in many respects different characteristics of tin(iv) phosphonates. The Sn(IV) monophosphonates form spherical globules that exhibit very high surface areas. The surface area arises from their nano-sized particles that pack in a "house of cards" arrangement. Also, it is shown that the 1,4-monophenyldiphosphonic acid forms highly porous (250-400 m2 g(-1)) materials with Sn(IV) when prepared in alcohol-water media. This is not the case with analogous Zr(IV) compounds. The many variations in the syntheses of both the zirconium and tin aryl- and alkyldiphosphonate pillars and their combinations with spacers such as methyl- and monophenylphosphonic acid have created a variety of highly porous materials that are stable to 400 degrees C in air, highly stable in acid media, do not collapse when de-solvated, and can be post and presynthesis altered to include functional groups. Several new directions taken by other researchers are also described. However, it is emphasized in this presentation that the cross-linked compounds form particles that precipitate rapidly into nanoparticles that exhibit only short range order. Therefore, they differ from the more conventional MOFs in that they are not amenable to structure solution by X-ray or neutron diffraction techniques. Rather, they must be understood on the basis of modeling and indirect data from EM, NMR, and additional spectroscopic and textural studies.