Energy level alignment at hybridized organic-metal interfaces from a GW projection approach

Science.gov (United States)

Chen, Yifeng; Tamblyn, Isaac; Quek, Su Ying

Energy level alignments at organic-metal interfaces are of profound importance in numerous (opto)electronic applications. Standard density functional theory (DFT) calculations generally give incorrect energy level alignments and missing long-range polarization effects. Previous efforts to address this problem using the many-electron GW method have focused on physisorbed systems where hybridization effects are insignificant. Here, we use state-of-the-art GW methods to predict the level alignment at the amine-Au interface, where molecular levels do hybridize with metallic states. This non-trivial hybridization implies that DFT result is a poor approximation to the quasiparticle states. However, we find that the self-energy operator is approximately diagonal in the molecular basis, allowing us to use a projection approach to predict the level alignments. Our results indicate that the metallic substrate reduces the HOMO-LUMO gap by 3.5 4.0 eV, depending on the molecular coverage/presence of Au adatoms. Our GW results are further compared with those of a simple image charge model that describes the level alignment in physisorbed systems. Syq and YC acknowledge Grant NRF-NRFF2013-07 and the medium-sized centre program from the National Research Foundation, Singapore.

On the Peculiar Molecular Shape and Size Dependence of the Dynamics of Fluids confined in a Small-Pore Metal-Organic Framework

KAUST Repository

Skarmoutsos, Ioannis; Eddaoudi, Mohamed; Maurin, Guillaume

2018-01-01

.e. the Metal-Organic Framework SIFSIX-2-Cu-i. These computations unveil an unprecedented molecular symmetry dependence of the translational and rotational dynamics of fluids confined in channel-like nanoporous materials. In particular this peculiar behaviour

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.

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

Current-Voltage Characteristics of the Metal / Organic Semiconductor / Metal Structures: Top and Bottom Contact Configuration Case

Directory of Open Access Journals (Sweden)

Šarūnas MEŠKINIS

2013-03-01

Full Text Available In present study five synthesized organic semiconductor compounds have been used for fabrication of the planar metal / organic semiconductor / metal structures. Both top electrode and bottom electrode configurations were used. Current-voltage (I-V characteristics of the samples were investigated. Effect of the hysteresis of the I-V characteristics was observed for all the investigated samples. However, strength of the hysteresis was dependent on the organic semiconductor used. Study of I-V characteristics of the top contact Al/AT-RB-1/Al structures revealed, that in (0 – 500 V voltages range average current of the samples measured in air is only slightly higher than current measured in nitrogen ambient. Deposition of the ultra-thin diamond like carbon interlayer resulted in both decrease of the hysteresis of I-V characteristics of top contact Al/AT-RB-1/Al samples. However, decreased current and decreased slope of the I-V characteristics of the samples with diamond like carbon interlayer was observed as well. I-V characteristic hysteresis effect was less pronounced in the case of the bottom contact metal/organic semiconductor/metal samples. I-V characteristics of the bottom contact samples were dependent on electrode metal used.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3816

Graphene inclusion controlling conductivity and gas sorption of metal-organic framework

OpenAIRE

Lamagni, Paolo; Pedersen, Birgitte Lodberg; Godiksen, Anita; Mossin, Susanne; Hu, Xin Ming; Pedersen, Steen Uttrup; Daasbjerg, Kim; Lock, Nina

2018-01-01

A general approach to prepare composite films of metal-organic frameworks and graphene has been developed. Films of copper(ii)-based HKUST-1 and HKUST-1/graphene composites were grown solvothermally on glassy carbon electrodes. The films were chemically tethered to the substrate by diazonium electrografting resulting in a large electrode coverage and good stability in solution for electrochemical studies. HKUST-1 has poor electrical conductivity, but we demonstrate that the addition of graphe...

Metal-organic extended 2D structures: Fe-PTCDA on Au(111)

International Nuclear Information System (INIS)

Alvarez, Lucia; Caillard, Renaud; MartIn-Gago, Jose A; Mendez, Javier; Pelaez, Samuel; Serena, Pedro A

2010-01-01

In this work we combine organic molecules of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with iron atoms on an Au (111) substrate in ultra-high vacuum conditions at different temperatures. By means of scanning tunnelling microscopy (STM) we study the formation of stable 2D metal-organic structures. We show that at certain growth conditions (temperature, time and coverage) stable 'ladder-like' nanostructures are obtained. These are the result of connecting together two metal-organic chains through PTCDA molecules placed perpendicularly, as rungs of a ladder. These structures, stable up to 450 K, can be extended in a 2D layer covering the entire surface and presenting different rotation domains. STM images at both polarities show a contrast reversal between the two molecules at the unit cell. By means of density functional theory (DFT) calculations, we confirm the stability of these structures and that their molecular orbitals are placed separately at the different molecules.

Coverage dependent molecular assembly of anthraquinone on Au(111)

Science.gov (United States)

DeLoach, Andrew S.; Conrad, Brad R.; Einstein, T. L.; Dougherty, Daniel B.

2017-11-01

A scanning tunneling microscopy study of anthraquinone (AQ) on the Au(111) surface shows that the molecules self-assemble into several structures depending on the local surface coverage. At high coverages, a close-packed saturated monolayer is observed, while at low coverages, mobile surface molecules coexist with stable chiral hexamer clusters. At intermediate coverages, a disordered 2D porous network interlinking close-packed islands is observed in contrast to the giant honeycomb networks observed for the same molecule on Cu(111). This difference verifies the predicted extreme sensitivity [J. Wyrick et al., Nano Lett. 11, 2944 (2011)] of the pore network to small changes in the surface electronic structure. Quantitative analysis of the 2D pore network reveals that the areas of the vacancy islands are distributed log-normally. Log-normal distributions are typically associated with the product of random variables (multiplicative noise), and we propose that the distribution of pore sizes for AQ on Au(111) originates from random linear rate constants for molecules to either desorb from the surface or detach from the region of a nucleated pore.

Fermi level dependent native defect formation: Consequences for metal-semiconductor and semiconductor-semiconductor interfaces

International Nuclear Information System (INIS)

Walukiewicz, W.

1988-02-01

The amphoteric native defect model of the Schottky barrier formation is used to analyze the Fermi level pinning at metal/semiconductor interfaces for submonolayer metal coverages. It is assumed that the energy required for defect generation is released in the process of surface back-relaxation. Model calculations for metal/GaAs interfaces show a weak dependence of the Fermi level pinning on the thickness of metal deposited at room temperature. This weak dependence indicates a strong dependence of the defect formation energy on the Fermi level, a unique feature of amphoteric native defects. This result is in very good agreement with experimental data. It is shown that a very distinct asymmetry in the Fermi level pinning on p- and n-type GaAs observed at liquid nitrogen temperatures can be understood in terms of much different recombination rates for amphoteric native defects in those two types of materials. Also, it is demonstrated that the Fermi level stabilization energy, a central concept of the amphoteric defect system, plays a fundamental role in other phenomena in semiconductors such as semiconductor/semiconductor heterointerface intermixing and saturation of free carrier concentration. 33 refs., 6 figs

The electric field at hole injecting metal/organic interfaces as a cause for manifestation of exponential bias-dependent mobility

International Nuclear Information System (INIS)

Cvikl, B.

2014-01-01

It is shown that the well-known empirical exponential bias-dependent mobility is an approximation function of the relevant term emerging in the Mott–Gurney space charge limited current model when the constant non-zero electric field at the hole injecting metal/organic interface E int is taken into account. The term in question is the product of the bias-independent (but organic layer thickness-dependent) effective mobility coefficient and the algebraic function, f(λ), of the argument λ = E int /E a , where E a is the externally applied electric field. On account of the non-zero interfacial field, E int , the singularity of the spatial dependence of the hole current density, p(x), is removed. The resulting hole drift current density, j, is tested as a function of E a against a number of published room temperature hole current j–E a data sets, all characterized by good ohmic contact at the hole injecting interface. It is shown that the calculated current density provides a very good fit to the measurements within a high range of E a intervals. Low values of E a , are investigated analytically under the assumption of hole drift-diffusion. The extremely large internal electric fields at the anode/organic junction indicate drift-diffusion to be an improbable process for the structures investigated. However, a description of hole transport throughout the whole interval of experimental E a values may be obtained at low values of E a by an extended Mark–Helfrich drift model with traps occupying the exponentially distributed energy levels, followed by the extended Mott–Gurney model description within the remaining part of the E a interval. In both models the same (bias-independent) effective mobility coefficient is incorporated into the calculations. The results present evidence that within the framework of the extended Mott–Gurney expression the properly derived term should replace the empirical exponential bias-dependent mobility, making it redundant in the

Model potential for the description of metal/organic interface states

Science.gov (United States)

Armbrust, Nico; Schiller, Frederik; Güdde, Jens; Höfer, Ulrich

2017-01-01

We present an analytical one-dimensional model potential for the description of electronic interface states that form at the interface between a metal surface and flat-lying adlayers of π-conjugated organic molecules. The model utilizes graphene as a universal representation of these organic adlayers. It predicts the energy position of the interface state as well as the overlap of its wave function with the bulk metal without free fitting parameters. We show that the energy of the interface state depends systematically on the bond distance between the carbon backbone of the adayers and the metal. The general applicability and robustness of the model is demonstrated by a comparison of the calculated energies with numerous experimental results for a number of flat-lying organic molecules on different closed-packed metal surfaces that cover a large range of bond distances. PMID:28425444

Analysis of the Science and Technology Narrative within Organ Donation and Transplantation Coverage in Canadian Newspapers

Directory of Open Access Journals (Sweden)

Jennifer Cheung

2015-04-01

Full Text Available Organ failure is one cause of death. Advancements in scientific research and technological development made organ transplantation possible and continue to find better ways to substitute failed organs with other organs of biological origin or artificial organs. Media, including newspapers, are one source of information for the public. The purpose of this study was to examine to what extent and how science and technology research and development are covered in the organ transplantation and organ donation (ODOT coverage of n = 300 Canadian newspapers, including the two Canadian newspapers with national reach (The Globe and Mail, National Post. The study generated qualitative and quantitative data addressing the following issues: (1 which scientific and technological developments are mentioned in the ODOT coverage; and (2 what issues are mentioned in the coverage of scientific and technological advancements linked to ODOT. We found little to no coverage of many technological and scientific advancements evident in academic and grey literature covering ODOT, and we found little engagement with social and ethical issues already raised about these advancements in the literature. The only area we found to be covered to a broader extent was xenotransplantation, although the coverage stopped after 2002. We argue that the newspaper coverage of ODOT under reports scientific and technological advancements related to ODOT and the issues these advancements might raise.

Quasiparticles and Fermi liquid behaviour in an organic metal

Science.gov (United States)

Kiss, T.; Chainani, A.; Yamamoto, H.M.; Miyazaki, T.; Akimoto, T.; Shimojima, T.; Ishizaka, K.; Watanabe, S.; Chen, C.-T.; Fukaya, A.; Kato, R.; Shin, S.

2012-01-01

Many organic metals display exotic properties such as superconductivity, spin-charge separation and so on and have been described as quasi-one-dimensional Luttinger liquids. However, a genuine Fermi liquid behaviour with quasiparticles and Fermi surfaces have not been reported to date for any organic metal. Here, we report the experimental Fermi surface and band structure of an organic metal (BEDT-TTF)3Br(pBIB) obtained using angle-resolved photoelectron spectroscopy, and show its consistency with first-principles band structure calculations. Our results reveal a quasiparticle renormalization at low energy scales (effective mass m*=1.9 me) and ω2 dependence of the imaginary part of the self energy, limited by a kink at ~50 meV arising from coupling to molecular vibrations. The study unambiguously proves that (BEDT-TTF)3Br(pBIB) is a quasi-2D organic Fermi liquid with a Fermi surface consistent with Shubnikov-de Haas results. PMID:23011143

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.

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 ...

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.

Improvement on post-OPC verification efficiency for contact/via coverage check by final CD biasing of metal lines and considering their location on the metal layout

Science.gov (United States)

Kim, Youngmi; Choi, Jae-Young; Choi, Kwangseon; Choi, Jung-Hoe; Lee, Sooryong

2011-04-01

As IC design complexity keeps increasing, it is more and more difficult to ensure the pattern transfer after optical proximity correction (OPC) due to the continuous reduction of layout dimensions and lithographic limitation by k1 factor. To guarantee the imaging fidelity, resolution enhancement technologies (RET) such as off-axis illumination (OAI), different types of phase shift masks and OPC technique have been developed. In case of model-based OPC, to cross-confirm the contour image versus target layout, post-OPC verification solutions continuously keep developed - contour generation method and matching it to target structure, method for filtering and sorting the patterns to eliminate false errors and duplicate patterns. The way to detect only real errors by excluding false errors is the most important thing for accurate and fast verification process - to save not only reviewing time and engineer resource, but also whole wafer process time and so on. In general case of post-OPC verification for metal-contact/via coverage (CC) check, verification solution outputs huge of errors due to borderless design, so it is too difficult to review and correct all points of them. It should make OPC engineer to miss the real defect, and may it cause the delay time to market, at least. In this paper, we studied method for increasing efficiency of post-OPC verification, especially for the case of CC check. For metal layers, final CD after etch process shows various CD bias, which depends on distance with neighbor patterns, so it is more reasonable that consider final metal shape to confirm the contact/via coverage. Through the optimization of biasing rule for different pitches and shapes of metal lines, we could get more accurate and efficient verification results and decrease the time for review to find real errors. In this paper, the suggestion in order to increase efficiency of OPC verification process by using simple biasing rule to metal layout instead of etch model

Effect of hydrogen coverage on hydrogenation of o-cresol on Pt(111)

Science.gov (United States)

Li, Yaping; Liu, Zhimin; Crossley, Steven P.; Jentoft, Friederike C.; Wang, Sanwu

2018-06-01

The conversion of phenolics over metal catalysts is an important process for upgrading biofuels. With density functional calculations, hydrogenation of o-cresol on the hydrogen-covered Pt(111) surface was investigated. The results show that the coverage of hydrogen plays a significant role in the reaction rate while it does not affect the reaction selectivity. The reaction barriers of the hydrogenation process leading to the formation of both 2-methyl-cyclohexanone (the intermediate product) and 2-methyl-cyclohexanol (the final product) at high H coverages (∼1 ML) are found to be smaller by 0.14-0.69 eV than those at lower H coverages (∼1/25 ML). After both hydrogen and cresol are adsorbed on Pt(111) from their initial gas phase state, the reaction energy of each hydrogenation step on the surface is also dependent on the hydrogen coverage. On the H-covered Pt(111) surface, most steps of hydrogenation involve exothermic reactions when the hydrogen coverage is high while they are endothermic reactions at low hydrogen coverages. The differences in reaction rate and reaction energy between high and low H coverages can be understood with the coverage-dependent bonding strength and configurations.

Electronic structure and electron dynamics at an organic molecule/metal interface: interface states of tetra-tert-butyl-imine/Au(111)

International Nuclear Information System (INIS)

Hagen, Sebastian; Wolf, Martin; Tegeder, Petra; Luo Ying; Haag, Rainer

2010-01-01

Time- and angle-resolved two-photon photoemission (2PPE) spectroscopies have been used to investigated the electronic structure, electron dynamics and localization at the interface between tetra-tert-butyl imine (TBI) and Au(111). At a TBI coverage of one monolayer (ML), the two highest occupied molecular orbitals, HOMO and HOMO-1, are observed at an energy of -1.9 and -2.6 eV below the Fermi level (E F ), respectively, and coincide with the d-band features of the Au substrate. In the unoccupied electronic structure, the lowest unoccupied molecular orbital (LUMO) has been observed at 1.6 eV with respect to E F . In addition, two delocalized states that arise from the modified image potential at the TBI/metal interface have been identified. Their binding energies depend strongly on the adsorption structure of the TBI adlayer, which is coverage dependent in the submonolayer (≤1 ML) regime. Thus the binding energy of the lower interface state (IS) shifts from 3.5 eV at 1.0 ML to 4.0 eV at 0.5 ML, which is accompanied by a pronounced decrease in its lifetime from 100 fs to below 10 fs. This is a result of differences in the wave function overlap with electronic states of the Au(111) substrate at different binding energies. This study shows that in order to fully understand the electronic structure of organic adsorbates at metal surfaces, not only adsorbate- and substrate-induced electronic states have to be considered but also ISs, which are the result of a potential formed by the interaction between the adsorbate and the substrate.

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)).

The challenges of social marketing of organ donation: news and entertainment coverage of donation and transplantation.

Science.gov (United States)

Harrison, Tyler R; Morgan, Susan E; Chewning, Lisa V

2008-01-01

While great strides have been made in persuading the public to become potential organ donors, actual behavior has not yet caught up with the nearly universally favorable attitudes the public expresses toward donation. This paper explores the issue by situating the social marketing of organ donation against a broader backdrop of entertainment and news media coverage of organ donation. Organ donation storylines are featured on broadcast television in medical and legal dramas, soap operas, and other television serials approximately four times per month (not including most cable networks), and feature storylines that promote myths and fears of the organ donation process. National news and other non-fictionalized coverage of organ donation are even more common, with stories appearing over twenty times a month on average. These stories tend to be one-dimensional and highly sensationalized in their coverage. The marketing of organ donation for entertainment essentially creates a counter-campaign to organ donation, with greater resources and reach than social marketers have access to. Understanding the broader environmental context of organ donation messages highlights the issues faced by social marketing campaigns in persuading the public to become potential donors.

Tunable photoluminescent metal-organic-frameworks and method of making the same

Energy Technology Data Exchange (ETDEWEB)

Nenoff, Tina M.; Sava Gallis, Dorina Florentina; Rohwer, Lauren E.S.

2017-08-22

The present disclosure is directed to new photoluminescent metal-organic frameworks (MOFs). The newly developed MOFs include either non rare earth element (REE) transition metal atoms or limited concentrations of REE atoms, including: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Ru, Ag, Cd, Sn, Sb, Ir, Pb, Bi, that are located in the MOF framework in site isolated locations, and have emission colors ranging from white to red, depending on the metal concentration levels and/or choice of ligand.

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.

The Impact of the Affordable Care Act's Dependent Coverage Mandate on Use of Dental Treatments and Preventive Services.

Science.gov (United States)

Shane, Dan M; Wehby, George L

2017-09-01

Oral health problems are the leading chronic conditions among children and younger adults. Lack of dental coverage is thought to be an important barrier to care but little empirical evidence exists on the causal effect of private dental coverage on use of dental services. We explore the relationship between dental coverage and dental services utilization with an analysis of a natural experiment of increasing private dental coverage stemming from the Affordable Care Act's (ACA)-dependent coverage mandate. To evaluate whether increased private dental insurance due to the spillover effect of the ACA-dependent coverage health insurance mandate affected utilization of dental services among a group of affected young adults. 2006-2013 Medical Expenditure Panel Surveys. We used a difference-in-difference regression approach comparing changes in dental care utilization for 25-year olds affected by the policy to unaffected 27-year olds. We evaluate effects on dental treatments and preventive services RESULTS:: Compared to 27-year olds, 25-year olds were 8 percentage points more likely to have private dental coverage in the 3 years following the mandate. We do not find compelling evidence that young adults increased their use of preventive dental services in response to gaining insurance. We do find a nearly 5 percentage point increase in the likelihood of dental treatments among 25-year olds following the mandate, an effect that appears concentrated among women. Increases in private dental coverage due to the ACA's-dependent coverage mandate do not appear to be driving significant changes in overall preventive dental services utilization but there is evidence of an increase in restorative care.

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.

Extent of hydrogen coverage of Si(001) under chemical vapor deposition conditions from ab initio approaches

International Nuclear Information System (INIS)

Rosenow, Phil; Tonner, Ralf

2016-01-01

The extent of hydrogen coverage of the Si(001) c(4 × 2) surface in the presence of hydrogen gas has been studied with dispersion corrected density functional theory. Electronic energy contributions are well described using a hybrid functional. The temperature dependence of the coverage in thermodynamic equilibrium was studied computing the phonon spectrum in a supercell approach. As an approximation to these demanding computations, an interpolated phonon approach was found to give comparable accuracy. The simpler ab initio thermodynamic approach is not accurate enough for the system studied, even if corrections by the Einstein model for surface vibrations are considered. The on-set of H 2 desorption from the fully hydrogenated surface is predicted to occur at temperatures around 750 K. Strong changes in hydrogen coverage are found between 1000 and 1200 K in good agreement with previous reflectance anisotropy spectroscopy experiments. These findings allow a rational choice for the surface state in the computational treatment of chemical reactions under typical metal organic vapor phase epitaxy conditions on Si(001).

Extent of hydrogen coverage of Si(001) under chemical vapor deposition conditions from ab initio approaches

Energy Technology Data Exchange (ETDEWEB)

Rosenow, Phil; Tonner, Ralf, E-mail: tonner@chemie.uni-marburg.de [Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften, Philipps-Universität Marburg, Hans-Meerwein-Straße, Marburg 35032 (Germany)

2016-05-28

The extent of hydrogen coverage of the Si(001) c(4 × 2) surface in the presence of hydrogen gas has been studied with dispersion corrected density functional theory. Electronic energy contributions are well described using a hybrid functional. The temperature dependence of the coverage in thermodynamic equilibrium was studied computing the phonon spectrum in a supercell approach. As an approximation to these demanding computations, an interpolated phonon approach was found to give comparable accuracy. The simpler ab initio thermodynamic approach is not accurate enough for the system studied, even if corrections by the Einstein model for surface vibrations are considered. The on-set of H{sub 2} desorption from the fully hydrogenated surface is predicted to occur at temperatures around 750 K. Strong changes in hydrogen coverage are found between 1000 and 1200 K in good agreement with previous reflectance anisotropy spectroscopy experiments. These findings allow a rational choice for the surface state in the computational treatment of chemical reactions under typical metal organic vapor phase epitaxy conditions on Si(001).

Extent of hydrogen coverage of Si(001) under chemical vapor deposition conditions from ab initio approaches

Science.gov (United States)

Rosenow, Phil; Tonner, Ralf

2016-05-01

The extent of hydrogen coverage of the Si(001) c(4 × 2) surface in the presence of hydrogen gas has been studied with dispersion corrected density functional theory. Electronic energy contributions are well described using a hybrid functional. The temperature dependence of the coverage in thermodynamic equilibrium was studied computing the phonon spectrum in a supercell approach. As an approximation to these demanding computations, an interpolated phonon approach was found to give comparable accuracy. The simpler ab initio thermodynamic approach is not accurate enough for the system studied, even if corrections by the Einstein model for surface vibrations are considered. The on-set of H2 desorption from the fully hydrogenated surface is predicted to occur at temperatures around 750 K. Strong changes in hydrogen coverage are found between 1000 and 1200 K in good agreement with previous reflectance anisotropy spectroscopy experiments. These findings allow a rational choice for the surface state in the computational treatment of chemical reactions under typical metal organic vapor phase epitaxy conditions on Si(001).

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

White organic light-emitting diodes with 4 nm metal electrode

Science.gov (United States)

Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Gather, Malte C.; Reineke, Sebastian

2015-10-01

We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

In situ characterization of the film coverage and the charge transport in the alkylated-organic thin film transistor

Science.gov (United States)

Watanabe, Takeshi; Koganezawa, Tomoyuki; Kikuchi, Mamoru; Muraoka, Hiroki; Ogawa, Satoshi; Yoshimoto, Noriyuki; Hirosawa, Ichiro

2018-03-01

We propose an in situ experimental method of investigating the correlations of the film coverage of the organic semiconductor layers and charge transport properties of organic thin film transistors during vacuum deposition. The coverage of each monolayer was estimated using the intensity of off-specular diffuse scattering and diffraction. Experimental data were obtained from the in situ measurements of two-dimensional grazing incidence X-ray scattering and charge transport. The source-drain current increased over the film coverage of the first monolayer (= 0.48). This is in agreement with the critical percolation coverage, indicating that the conductivities of the first and second monolayers are different.

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.

Modeling the state dependent impulse control for computer virus propagation under media coverage

Science.gov (United States)

Liang, Xiyin; Pei, Yongzhen; Lv, Yunfei

2018-02-01

A state dependent impulsive control model is proposed to model the spread of computer virus incorporating media coverage. By the successor function, the sufficient conditions for the existence and uniqueness of order-1 periodic solution are presented first. Secondly, for two classes of periodic solutions, the geometric property of successor function and the analogue of the Poincaré criterion are employed to obtain the stability results. These results show that the number of the infective computers is under the threshold all the time. Finally, the theoretic and numerical analysis show that media coverage can delay the spread of computer virus.

Vibrations of alkali metal overlayers on metal surfaces

International Nuclear Information System (INIS)

Rusina, G G; Eremeev, S V; Borisova, S D; Echenique, P M; Chulkov, E V; Benedek, G

2008-01-01

We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation

75 FR 27141 - Group Health Plans and Health Insurance Issuers Providing Dependent Coverage of Children to Age...

Science.gov (United States)

2010-05-13

... Group Health Plans and Health Insurance Issuers Providing Dependent Coverage of Children to Age 26 Under... Information and Insurance Oversight of the U.S. Department of Health and Human Services are issuing substantially similar interim final regulations with respect to group health plans and health insurance coverage...

Investigating the coverage dependent behaviour of CO on Gd/Pt(111)

DEFF Research Database (Denmark)

Ulrikkeholm, Elisabeth Therese; Hansen, Martin Hangaard; Rossmeisl, Jan

2016-01-01

diffraction (LEED), showing that a highly ordered crystal structure had appeared. To study the molecular dynamics on this surface a detailed study of the CO adsorption on the surface was conducted using temperature programmed desorption (TPD) of CO. The TPD spectra show a desorption peak shifted down...... in temperature compared to those of pure Pt(111). The shape of the desorption peak and the desorption temperature were shown to be strongly dependent on the CO coverage of the surface. A systematic investigation of CO desorption temperature as a function of coverage was consequently performed. A simple...... simulation of the TPD spectra was carried out, based on adsorption energies from density functional theory (DFT). This simulation reproduces the shift and the narrowing of the desorption spectrum from the experiments and the DFT calculations suggest that the sharp TPD feature arises from cooperative...

A review of metal (Pb and Zn) sensitive and pH tolerant bioassay organisms for risk screening of metal-contaminated acidic soils

International Nuclear Information System (INIS)

Chapman, E.Emily V.; Dave, Göran; Murimboh, John D.

2013-01-01

To improve risk estimates at the screening stage of Ecological Risk Assessment (ERA), short duration bioassays tailored to undisturbed soil cores from the contaminated site could be useful. However, existing standardized bioassays use disturbed soil samples and often pH sensitive organisms. This is a problem as naturally acidic soils are widespread. Changing soil properties to suit the test organism may change metal bioavailability, leading to erroneous risk estimates. For bioassays in undisturbed soil cores to be effective, species able to withstand natural soil properties must be identified. This review presents a critical examination of bioassay species' tolerance of acidic soils and sensitivity to metal contaminants such as Pb and Zn. Promising organisms include; Dendrobaena octaedra, Folsomia candida, Caenorhabditis elegans, Oppia nitens, Brassica rapa, Trifolium pratense, Allium cepa, Quercus rubra and Acer rubrum. The MetSTICK test and the Bait lamina test were also identified as suitable microorganism tests. -- Highlights: •Risk screening of metal contaminated soils should consider metal bioavailability. •Metal bioavailability is dependent on soil properties such as pH. •Many standardized bioassay organisms are sensitive to acidic soils. •This review identifies acid tolerant and metal sensitive bioassays and species. •The identified tests can improve risk screening of acidic metal contaminated soil. -- This review identifies bioassay species able to withstand naturally acidic soils while being sensitive to metal contaminants

The structure of organic langmuir films on liquid metal surfaces

International Nuclear Information System (INIS)

Kraack, H.; Deutsch, M.; Ocko, B.M.; Pershan, P.S.

2003-01-01

Langmuir films (LFs) on water have long been studied for their interest for basic science and their numerous applications in chemistry, physics, materials science and biology. We present here A-resolution synchrotron X-ray studies of the structure of stearic acid LFs on a liquid mercury surface. At low coverage, ≥110 A 2 /mol, a 2D gas phase of flat-lying molecules is observed. At high coverage, ≤23 A 2 /mol, two different hexatic phases of standing-up molecules are observed. At intermediate coverage, 52≤A≤110 A 2 /mol, novel single- and double-layered phases of flat-lying molecular dimers are found, exhibiting a 1D in-layer order. Such flat-lying phases were not hitherto observed in any LF. Measurements on LFs of fatty acids of other chain lengths indicate that this structure is generic to chain molecules on mercury, although the existence of some of the flat-lying phases, and the observed phase sequence, depend on the chain length. Organic LFs on Hg, and in particular the new flat-lying phases, should provide a broader nano-structural tunability range for molecular electronic device construction than most solid-supported self-assembled monolayers used at present

Identifying sources of metal exposure in organic and conventional dairy farming.

Science.gov (United States)

López-Alonso, M; Rey-Crespo, F; Herrero-Latorre, C; Miranda, M

2017-10-01

In humans the main route of exposure to toxic metals is through the diet, and there is therefore a clear need for this source of contamination to be minimized, particularly in food of animal origin. For this purpose, the various sources of toxic metals in livestock farming (which vary depending on the production system) must be taken into account. The objectives of the present study were to establish the profile of metal exposure in dairy cattle in Spain and to determine, by chemometric (multivariate statistical) analysis, any differences between organic and conventional systems. Blood samples from 522 cows (341 from organic farms and 181 from conventional farms) were analysed by inductively coupled plasma mass spectrometry to determine the concentrations of 14 elements: As, Cd, Co, Cr, Cu, Fe, Hg, I, Mn, Mo, Ni, Pb, Se and Zn. In conventional systems the generally high and balanced trace element concentrations in the mineral-supplemented concentrate feed strongly determined the metal status of the cattle. However, in organic systems, soil ingestion was an important contributing factor. Our results demonstrate that general information about the effects of mineral supplementation in conventional farming cannot be directly extrapolated to organic farming and special attention should be given to the contribution of ingestion of soil during grazing and/or ingestion of soil contaminated forage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Energy-level alignment at metal-organic and organic-organic interfaces

NARCIS (Netherlands)

Veenstra, Sjoerd; Jonkman, H.T.

2003-01-01

This article reports on the electronic structure at interfaces found in organic semiconductor devices. The studied organic materials are C-60 and poly (para-phenylenevinylene) (PPV)-like oligomers, and the metals are polycrystalline Au and Ag. To measure the energy levels at these interfaces,

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.

Graphene inclusion controlling conductivity and gas sorption of metal-organic framework

DEFF Research Database (Denmark)

Lamagni, Paolo; Pedersen, Birgitte Lodberg; Godiksen, Anita

2018-01-01

A general approach to prepare composite films of metal-organic frameworks and graphene has been developed. Films of copper(ii)-based HKUST-1 and HKUST-1/graphene composites were grown solvothermally on glassy carbon electrodes. The films were chemically tethered to the substrate by diazonium...... electrografting resulting in a large electrode coverage and good stability in solution for electrochemical studies. HKUST-1 has poor electrical conductivity, but we demonstrate that the addition of graphene to HKUST-1 partially restores the electrochemical activity of the electrodes. The enhanced activity......, however, does not result in copper(ii) to copper(i) reduction in HKUST-1 at negative potentials. The materials were characterised in-depth: microscopy and grazing incidence X-ray diffraction demonstrate uniform films of crystalline HKUST-1, and Raman spectroscopy reveals that graphene is homogeneously...

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

Science.gov (United States)

Kim, In Soo; Li, Zhanyong; Zheng, Jian; Platero-Prats, Ana E; Mavrandonakis, Andreas; Pellizzeri, Steven; Ferrandon, Magali; Vjunov, Aleksei; Gallington, Leighanne C; Webber, Thomas E; Vermeulen, Nicolaas A; Penn, R Lee; Getman, Rachel B; Cramer, Christopher J; Chapman, Karena W; Camaioni, Donald M; Fulton, John L; Lercher, Johannes A; Farha, Omar K; Hupp, Joseph T; Martinson, Alex B F

2018-01-22

Single atoms and few-atom clusters of platinum are uniformly 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 °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 X-ray 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. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

White organic light-emitting diodes with 4 nm metal electrode

Energy Technology Data Exchange (ETDEWEB)

Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Reineke, Sebastian [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden (Germany); Gather, Malte C. [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden (Germany); Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom)

2015-10-19

We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

Impact of metal and anion substitutions on the hydrogen storage properties of M-BTT metal-organic frameworks.

Science.gov (United States)

Sumida, Kenji; Stück, David; Mino, Lorenzo; Chai, Jeng-Da; Bloch, Eric D; Zavorotynska, Olena; Murray, Leslie J; Dincă, Mircea; Chavan, Sachin; Bordiga, Silvia; Head-Gordon, Martin; Long, Jeffrey R

2013-01-23

Microporous metal-organic frameworks are a class of materials being vigorously investigated for mobile hydrogen storage applications. For high-pressure storage at ambient temperatures, the M(3)[(M(4)Cl)(3)(BTT)(8)](2) (M-BTT; BTT(3-) = 1,3,5-benzenetristetrazolate) series of frameworks are of particular interest due to the high density of exposed metal cation sites on the pore surface. These sites give enhanced zero-coverage isosteric heats of adsorption (Q(st)) approaching the optimal value for ambient storage applications. However, the Q(st) parameter provides only a limited insight into the thermodynamics of the individual adsorption sites, the tuning of which is paramount for optimizing the storage performance. Here, we begin by performing variable-temperature infrared spectroscopy studies of Mn-, Fe-, and Cu-BTT, allowing the thermodynamics of H(2) adsorption to be probed experimentally. This is complemented by a detailed DFT study, in which molecular fragments representing the metal clusters within the extended solid are simulated to obtain a more thorough description of the structural and thermodynamic aspects of H(2) adsorption at the strongest binding sites. Then, the effect of substitutions at the metal cluster (metal ion and anion within the tetranuclear cluster) is discussed, showing that the configuration of this unit indeed plays an important role in determining the affinity of the framework toward H(2). Interestingly, the theoretical study has identified that the Zn-based analogs would be expected to facilitate enhanced adsorption profiles over the compounds synthesized experimentally, highlighting the importance of a combined experimental and theoretical approach to the design and synthesis of new frameworks for H(2) storage applications.

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

Highly reproducible alkali metal doping system for organic crystals through enhanced diffusion of alkali metal by secondary thermal activation.

Science.gov (United States)

Lee, Jinho; Park, Chibeom; Song, Intek; Koo, Jin Young; Yoon, Taekyung; Kim, Jun Sung; Choi, Hee Cheul

2018-05-16

In this paper, we report an efficient alkali metal doping system for organic single crystals. Our system employs an enhanced diffusion method for the introduction of alkali metal into organic single crystals by controlling the sample temperature to induce secondary thermal activation. Using this system, we achieved intercalation of potassium into picene single crystals with closed packed crystal structures. Using optical microscopy and Raman spectroscopy, we confirmed that the resulting samples were uniformly doped and became K 2 picene single crystal, while only parts of the crystal are doped and transformed into K 2 picene without secondary thermal activation. Moreover, using a customized electrical measurement system, the insulator-to-semiconductor transition of picene single crystals upon doping was confirmed by in situ electrical conductivity and ex situ temperature-dependent resistivity measurements. X-ray diffraction studies showed that potassium atoms were intercalated between molecular layers of picene, and doped samples did not show any KH- nor KOH-related peaks, indicating that picene molecules are retained without structural decomposition. During recent decades, tremendous efforts have been exerted to develop high-performance organic semiconductors and superconductors, whereas as little attention has been devoted to doped organic crystals. Our method will enable efficient alkali metal doping of organic crystals and will be a resource for future systematic studies on the electrical property changes of these organic crystals upon doping.

Impacts of metal and metal oxide nanoparticles on marine organisms

International Nuclear Information System (INIS)

Baker, Tony J.; Tyler, Charles R.; Galloway, Tamara S.

2014-01-01

Increasing use of metal and metal oxide nanoparticles [Me(O)NPs] in products means many will inevitably find their way into marine systems. Their likely fate here is sedimentation following hetero-aggregation with natural organic matter and/or free anions, putting benthic, sediment-dwelling and filter feeding organisms most at risk. In marine systems, Me(O)NPs can absorb to micro-organisms with potential for trophic transfer following consumption. Filter feeders, especially bivalves, accumulate Me(O)NPs through trapping them in mucus prior to ingestion. Benthic in-fauna may directly ingest sedimented Me(O)NPs. In fish, uptake is principally via the gut following drinking, whilst Me(O)NPs caught in gill mucus may affect respiratory processes and ion transport. Currently, environmentally-realistic Me(O)NP concentrations are unlikely to cause significant adverse acute health problems, however sub-lethal effects e.g. oxidative stresses have been noted in many organisms, often deriving from dissolution of Ag, Cu or Zn ions, and this could result in chronic health impacts. -- Highlights: • Nanoparticle (NP) use increasing, and NPs ultimately discharged to marine systems. • Metal ion dissolution from NPs causes oxidative stress at relevant concentrations. • Bioaccumulation and trophic transfer of NPs likely at all levels of marine food webs. • Biofilms and filter feeders are major NP accumulators, but many Classes lack study. • Current release levels unlikely to cause chronic damage, but may be a future issue. -- Exposure to metal (oxide) nanoparticles causes sub-lethal effects in marine organisms, the extent of which is related principally to the organisms' feeding regime, habitat and lifestyle

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.

Zeolite-like metal-organic frameworks with ana topology

KAUST Repository

Eddaoudi, Mohamed; Mohideen, Mohamed Infas Haja; Adil, Karim; Belmabkhout, Youssef; Bhatt, Prashant M.; Shekhah, Osama; Chernikova, Valeriya

2017-01-01

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

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.

Richness, coverage and concentration of heavy metals in vascular epiphytes along an urbanization gradient.

Science.gov (United States)

Becker, Diego Fedrizzi Petry; Linden, Rafael; Schmitt, Jairo Lizandro

2017-04-15

Richness, coverage and concentration of heavy metals in vascular epiphytes were analyzed in isolated trees along an urbanization gradient in Southern Brazil. A total of 20 phorophytes were sampled in the main street of each site. Concentrations of chromium, cadmium, lead, manganese, nickel and zinc were measured in the leaves of Tillandsia recurvata L. using Graphite Furnace Atomic Absorption Spectrophotometry. A decreasing gradient of epiphyte richness and coverage was observed as urbanization increased. Vehicle fleet and demographic density were the parameters most correlated with the reduction of epiphytic diversity. In T. recurvata, significantly higher values of cadmium, lead and zinc were recorded in the most urbanized areas, and were strongly related to the vehicle fleet and to the demographic density in these sites. The results demonstrated that these parameters could be applied to the diagnosis of environmental quality in urban areas, allowing standardized analyses in other regions. Copyright © 2017 Elsevier B.V. All rights reserved.

Iron phthalocyanine on Cu(111): Coverage-dependent assembly and symmetry breaking, temperature-induced homocoupling, and modification of the adsorbate-surface interaction by annealing.

Science.gov (United States)

Snezhkova, Olesia; Bischoff, Felix; He, Yuanqin; Wiengarten, Alissa; Chaudhary, Shilpi; Johansson, Niclas; Schulte, Karina; Knudsen, Jan; Barth, Johannes V; Seufert, Knud; Auwärter, Willi; Schnadt, Joachim

2016-03-07

We have examined the geometric and electronic structures of iron phthalocyanine assemblies on a Cu(111) surface at different sub- to mono-layer coverages and the changes induced by thermal annealing at temperatures between 250 and 320 °C by scanning tunneling microscopy, x-ray photoelectron spectroscopy, and x-ray absorption spectroscopy. The symmetry breaking observed in scanning tunneling microscopy images is found to be coverage dependent and to persist upon annealing. Further, we find that annealing to temperatures between 300 and 320 °C leads to both desorption of iron phthalocyanine molecules from the surface and their agglomeration. We see clear evidence of temperature-induced homocoupling reactions of the iron phthalocyanine molecules following dehydrogenation of their isoindole rings, similar to what has been observed for related tetrapyrroles on transition metal surfaces. Finally, spectroscopy indicates a modified substrate-adsorbate interaction upon annealing with a shortened bond distance. This finding could potentially explain a changed reactivity of Cu-supported iron phthalocyanine in comparison to that of the pristine compound.

Characteristics of Young Adults Enrolled Through the Affordable Care Act-Dependent Coverage Expansion.

Science.gov (United States)

Han, Xuesong; Zhu, Shiyun; Jemal, Ahmedin

2016-12-01

The purpose of this study was to examine sociodemographic and health care-related characteristics of young adults covered through the Affordable Care Act (ACA)-dependent coverage expansion. Our sample consisted of 36,802 young adults aged 19-25 years from 2011 to 2014 National Health Interview Survey. Sociodemographic differences among young adults with the four insurance types were described: privately insured under parents, privately insured under self/spouse, publicly insured, and uninsured. Multivariable logistic models were fitted to compare those covered under parent with those covered through other traditional insurance types, in terms of the following outcomes: health status, health behaviors, insurance history and experience, access to care, care utilization, and receipt of preventive service, controlling for sociodemographic factors. Young adults who were covered under their parents' insurance were most likely to be college students and non-Hispanic whites. These young adults also had more stable insurance, better access to care, better care utilization patterns, and reported better health status, compared to their peers. The beneficiaries of the ACA-dependent coverage expansion were more likely to be college students from families with high socioeconomic status. Coverage under parents was associated with improved access to care and health outcomes among young adults. The enrollees through the ACA represent the healthiest subgroup of young adults and those with the best care utilization patterns, suggesting that the added cost relative to premium for insurers from this population will likely be minimal. Copyright © 2016 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Hydrogen storage in metal-organic frameworks: A review

CSIR Research Space (South Africa)

Langmi, Henrietta W

2014-05-01

Full Text Available Metal-organic frameworks (MOFs) for hydrogen storage have continued to receive intense interest over the past decade. MOFs are a class of organic-inorganic hybrid crystalline materials consisting of metallic moieties that are linked by strong...

SDSS-IV MaNGA: modelling the metallicity gradients of gas and stars - radially dependent metal outflow versus IMF

Science.gov (United States)

Lian, Jianhui; Thomas, Daniel; Maraston, Claudia; Goddard, Daniel; Parikh, Taniya; Fernández-Trincado, J. G.; Roman-Lopes, Alexandre; Rong, Yu; Tang, Baitian; Yan, Renbin

2018-05-01

In our previous work, we found that only two scenarios are capable of reproducing the observed integrated mass-metallicity relations for the gas and stellar components of local star-forming galaxies simultaneously. One scenario invokes a time-dependent metal outflow loading factor with stronger outflows at early times. The other scenario uses a time-dependent initial mass function (IMF) slope with a steeper IMF at early times. In this work, we extend our study to investigate the radial profile of gas and stellar metallicity in local star-forming galaxies using spatially resolved spectroscopic data from the SDSS-IV MaNGA survey. We find that most galaxies show negative gradients in both gas and stellar metallicity with steeper gradients in stellar metallicity. The stellar metallicity gradients tend to be mass dependent with steeper gradients in more massive galaxies while no clear mass dependence is found for the gas metallicity gradient. Then we compare the observations with the predictions from a chemical evolution model of the radial profiles of gas and stellar metallicities. We confirm that the two scenarios proposed in our previous work are also required to explain the metallicity gradients. Based on these two scenarios, we successfully reproduce the radial profiles of gas metallicity, stellar metallicity, stellar mass surface density, and star formation rate surface density simultaneously. The origin of the negative gradient in stellar metallicity turns out to be driven by either radially dependent metal outflow or IMF slope. In contrast, the radial dependence of the gas metallicity is less constrained because of the degeneracy in model parameters.

Ionic Transport Through Metal-Rich Organic Coatings

Science.gov (United States)

2016-08-19

organic paints, inert metallic layers, and protective oxide layers. 2 Although coatings have been commercially used for many years, the design of new...pigments found in chromates protect the substrate by passivating the metallic surface with an oxide layer. Sacrificial coatings prevent the self...surface, eliminating the components needed for a cathodic reaction to occur. Additionally, organic barrier coatings are protective by preventing

Microarray study of temperature-dependent sensitivity and selectivity of metal/oxide sensing interfaces

Science.gov (United States)

Tiffany, Jason; Cavicchi, Richard E.; Semancik, Stephen

2001-02-01

Conductometric gas microsensors offer the benefits of ppm-level sensitivity, real-time data, simple interfacing to electronics hardware, and low power consumption. The type of device we have been exploring consists of a sensor film deposited on a "microhotplate"- a 100 micron platform with built-in heating (to activate reactions on the sensing surface) and thermometry. We have been using combinatorial studies of 36-element arrays to characterize the relationship between sensor film composition, operating temperature, and response, as measured by the device's sensitivity and selectivity. Gases that have been tested on these arrays include methanol, ethanol, dichloromethane, propane, methane, acetone, benzene, hydrogen, and carbon monoxide, and are of interest in the management of environmental waste sites. These experiments compare tin oxide films modified by catalyst overlayers, and ultrathin metal seed layers. The seed layers are used as part of a chemical vapor deposition process that uses each array element's microheater to activate the deposition of SnO2, and control its microstructure. Low coverage (20 Ê) catalytic metals (Pd, Cu, Cr, In, Au) are deposited on the oxides by masked evaporation or sputtering. This presentation demonstrates the value of an array-based approach for developing film processing methods, measuring performance characteristics, and establishing reproducibility. It also illustrates how temperature-dependent response data for varied metal/oxide compositions can be used to tailor a microsensor array for a given application.

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:

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

The relationship between metal toxicity and biotic ligand binding affinities in aquatic and soil organisms: a review.

Science.gov (United States)

Ardestani, Masoud M; van Straalen, Nico M; van Gestel, Cornelis A M

2014-12-01

The biotic ligand model (BLM) is a theoretical, potentially mechanistic approach to assess metal bioavailability in soil and aquatic systems. In a BLM, toxicity is linked to the fraction of biotic ligand occupied, which in turn, depends on the various components of the solution, including activity of the metal. Bioavailability is a key factor in determining toxicity and uptake of metals in organisms. In this study, the present status of BLM development for soil and aquatic organisms is summarized. For all species and all metals, toxicity was correlated with the conditional biotic ligand binding constants. For almost all organisms, values for Ag, Cu, and Cd were higher than those for Zn and Ni. The constants derived for aquatic systems seem to be equally valid for soil organisms, but in the case of soils, bioavailability from the soil solution is greatly influenced by the presence of the soil solid phase. Copyright © 2014 Elsevier Ltd. All rights reserved.

Did the dependent coverage expansion increase risky substance use among young adults?

Science.gov (United States)

Breslau, Joshua; Yu, Hao; Han, Bing; Pacula, Rosalie L; Burns, Rachel M; Stein, Bradley D

2017-09-01

The dependent coverage expansion (DCE) enacted through the Affordable Care Act increased health insurance coverage among young adults. Increasing insurance coverage in this age group has the potential for unintended consequences on risky substance use. Repeated cross-sectional surveys were used to compare change in substance use during the period the DCE was implemented in the 19-25year old target age group (Pre-DCE n=15,772, Post-DCE n=22,719) with contemporaneous change in a slightly older age group that was not targeted by the policy (Pre-DCE=19,851, Post-DCE n=28,157). Outcomes include 11 measures of alcohol, illicit drug and cigarette use. Statistical controls were included for demographic and socioeconomic factors and for early initiation of substance use to adjust for historical trends in developmental trajectories. Risky substance use decreased in young adults relative to the older age group over the period that the DCE was implemented. However, statistical adjustment for initiation of substance use prior to age 18, which is prior to exposure to the DCE, accounted for the differences between the age groups. In adjusted models, associations between the DCE and substance use outcomes range from 0.96 to 1.08 with p-values ranging from 0.330 to 0.963. Historical trends in initiation of substance use prior to age 18, not the DCE, account for change in risky substance use among 19-25year olds relative to 26-34year olds. The evidence does not support the suggestion that health insurance coverage would increase risky substance use among young adults. Copyright © 2017 Elsevier B.V. All rights reserved.

Synchrotron far-IR RAIRS studies of interfaces created by polyfunctional organic molecules at defined metal surfaces

International Nuclear Information System (INIS)

Raval, R.; Williams, J.; Roberts, A.J.; Nunney, T.S.; Surman, M.

1998-01-01

Far-IR Reflection Absorption Infrared Spectroscopy (RAIRS) has been used to probe sub monolayers and multilayers of polyfunctional organic ad layers deposited under clean controlled conditions on small-area single-crystal surfaces, using the newly commissioned Daresbury 13.3 far-IR synchrotron beamline. It's shown that the current performance of the beamline allows to monitor fractions of monolayers of formate species on Cu(110), formed at 300 K from the deprotonation of formic acid. Two distinct vCu-O vibrations are observed for coverages up to 0.25 monolayer. The paper attributes the two bands to at least two chemically distinct species, each possessing a local site symmetry of C 2v and bonded to the metal surface via the two oxygen atoms. The two types of formate species are thought to arise from local density fluctuations in formate coverage across the ad layer which leads to local changes in the Cu-O bond. In additions, it's reported far-IR RAIRS spectra of bio molecule/metal interfaces created by depositing thin films (3-10 layers) of the chiral amino-acid, L-methionine, on Cu(110) at 300 K. The multilayer spectra closely resemble the far-IR spectra obtained from crystalline L-methionine, suggesting that the thin layer consists of the zwitterionic species. These thin bio films are stable on the surface to >330 K. No growth of metal-ligand vibrations in the multilayer phase is observed, demonstrating that corrosive chemisorption processes that create Cu-methionine complexes in the multilayer by leaching of surface Cu atoms do not occur in these conditions

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

Ionic Transport Through Metal-Rich Organic Coatings

Science.gov (United States)

2016-08-19

important for metal substrates, as it is well-known that chloride increases corrosion of metals . 3 For metal -loaded primers, it has been established...volume (MPV) percent, solvent polarity, and resin molecular weight impact corrosion protection of metal -rich organic (MRO) coatings. Following design of...pH and chloride ion concentration levels over time. As the corrosion protection of the coating decreases, chloride ion concentration will increase

Measuring time-dependent deformations in metallic MEMS

NARCIS (Netherlands)

Bergers, L.I.J.C.; Hoefnagels, J.P.M.; Delhey, N.K.R.; Geers, M.G.D.

2011-01-01

The reliability of metallic microelectromechanical systems (MEMS) depends on time-dependent deformation such as creep. Key to this process is the interaction between microstructural length scales and dimensional length scales, so-called size-effects. As a first critical step towards studying these

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

Reconfigurable electronics using conducting metal-organic frameworks

Science.gov (United States)

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.

Methane storage in metal-organic frameworks.

Science.gov (United States)

He, Yabing; Zhou, Wei; Qian, Guodong; Chen, Banglin

2014-08-21

Natural gas (NG), whose main component is methane, is an attractive fuel for vehicular applications. Realization of safe, cheap and convenient means and materials for high-capacity methane storage can significantly facilitate the implementation of natural gas fuelled vehicles. The physisorption based process involving porous materials offers an efficient storage methodology and the emerging porous metal-organic frameworks have been explored as potential candidates because of their extraordinarily high porosities, tunable pore/cage sizes and easily immobilized functional sites. In this view, we provide an overview of the current status of metal-organic frameworks for methane storage.

Charge transfer and injection barrier at the metal-organic interfaces

Science.gov (United States)

Yan, Li

2002-09-01

The metal-organic interface plays a critical role in determining the functionality and performance of many innovative organic based devices. It has attracted extensive research interests in recent years. This thesis presents investigations of the electronic structures of organic materials, such as tris-(8-hydroxyquinoline) aluminum (Alq3) and copper phthalocyanine (CuPc), during their interface formation with metals. The characterization is accomplished by X-ray and ultraviolet photoelectron spectroscopes (XPS and UPS) and inverse photoelectron spectroscopy (IPES). As discussed herein, both occupied and unoccupied electronic states at the interfaces are carefully examined in different aspects. In Chapter 4, the charge transfer and chemical reaction at various metal/Alq3 interfaces are investigated using XPS and UPS to study the electron injection into the Alga film. Electron transfer from the low work function metal and Al/LiF(CsF) bilayer to the Alga has been observed. The role of the dielectric and possible chemistry at the interface are discussed in comparison of the low work function metals. Further in Chapter 5, the origin of the metal-interface dipole and the estimation of charge injection barrier is explored using several organic materials. A thermodynamic equilibrium model is extended to explain the relation between the charge transfer process ad the interface dipole. Further, in Chapter 6 the combination of XPS, UPS and IPES detailed the evolution of both occupied and unoccupied energy states during the alkali metal doping. The energy gap modification in organic due to metal doping is observed directly for the spectra. Chapter 7 provides stability study of the organic thin films under x-ray and UV light. The results verify the usability of UPS and XPS for the organic materials used in the thesis. Chapter 7 also shows the secondary ion mass spectroscopy results of metal diffusion in organic thin films.

Reducing Young Adults' Health Care Spending through the ACA Expansion of Dependent Coverage.

Science.gov (United States)

Chen, Jie; Vargas-Bustamante, Arturo; Novak, Priscilla

2017-10-01

To estimate health care expenditure trends among young adults ages 19-25 before and after the 2010 implementation of the Affordable Care Act (ACA) provision that extended eligibility for dependent private health insurance coverage. Nationally representative Medical Expenditure Panel Survey data from 2008 to 2012. We conducted repeated cross-sectional analyses and employed a difference-in-differences quantile regression model to estimate health care expenditure trends among young adults ages 19-25 (the treatment group) and ages 27-29 (the control group). Our results show that the treatment group had 14 percent lower overall health care expenditures and 21 percent lower out-of-pocket payments compared with the control group in 2011-2012. The overall reduction in health care expenditures among young adults ages 19-25 in years 2011-2012 was more significant at the higher end of the health care expenditure distribution. Young adults ages 19-25 had significantly higher emergency department costs at the 10th percentile in 2011-2012. Differences in the trends of costs of private health insurance and doctor visits are not statistically significant. Increased health insurance enrollment as a consequence of the ACA provision for dependent coverage has successfully reduced spending and catastrophic expenditures, providing financial protections for young adults. © Health Research and Educational Trust.

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.

Bioremediation of Heavy Metals and Organic Toxicants by Composting

Directory of Open Access Journals (Sweden)

Allen V. Barker

2002-01-01

Full Text Available Hazardous organic and metallic residues or by-products can enter into plants, soils, and sediments from processes associated with domestic, municipal, agricultural, industrial, and military activities. Handling, ingestion, application to land or other distributions of the contaminated materials into the environment might render harm to humans, livestock, wildlife, crops, or native plants. Considerable remediation of the hazardous wastes or contaminated plants, soils, and sediments can be accomplished by composting. High microbial diversity and activity during composting, due to the abundance of substrates in feedstocks, promotes degradation of xenobiotic organic compounds, such as pesticides, polycyclic aromatic hydrocarbons (PAHs, and polychlorinated biphenyls (PCBs. For composting of contaminated soils, noncontaminated organic matter should be cocomposted with the soils. Metallic pollutants are not degraded during composting but may be converted into organic combinations that have less bioavailability than mineral combinations of the metals. Degradation of organic contaminants in soils is facilitated by addition of composted or raw organic matter, thereby increasing the substrate levels for cometabolism of the contaminants. Similar to the composting of soils in vessels or piles, the on-site addition of organic matter to soils (sheet composting accelerates degradation of organic pollutants and binds metallic pollutants. Recalcitrant materials, such as organochlorines, may not undergo degradation in composts or in soils, and the effects of forming organic complexes with metallic pollutants may be nonpermanent or short lived. The general conclusion is, however, that composting degrades or binds pollutants to innocuous levels or into innocuous compounds in the finished product.

Graphene transfer process and optimization of graphene coverage

OpenAIRE

Sabki Syarifah Norfaezah; Shamsuri Shafiq Hafly; Fauzi Siti Fazlina; Chon-Ki Meghashama Lim; Othman Noraini

2017-01-01

Graphene grown on transition metal is known to be high in quality due to its controlled amount of defects and potentially used for many electronic applications. The transfer process of graphene grown on transition metal to a new substrate requires optimization in order to ensure that high graphene coverage can be obtained. In this work, an improvement in the graphene transfer process is performed from graphene grown on copper foil. It has been observed that the graphene coverage is affected b...

Comparison of Organ Location, Morphology, and Rib Coverage of a Midsized Male in the Supine and Seated Positions

Directory of Open Access Journals (Sweden)

Ashley R. Hayes

2013-01-01

Full Text Available The location and morphology of abdominal organs due to postural changes have implications in the prediction of trauma via computational models. The purpose of this study is to use data from a multimodality image set to devise a method for examining changes in organ location, morphology, and rib coverage from the supine to seated postures. Medical images of a male volunteer (78.6±0.77 kg, 175 cm in three modalities (Computed Tomography, Magnetic Resonance Imaging (MRI, and Upright MRI were used. Through image segmentation and registration, an analysis between organs in each posture was conducted. For the organs analyzed (liver, spleen, and kidneys, location was found to vary between postures. Increases in rib coverage from the supine to seated posture were observed for the liver, with a 9.6% increase in a lateral projection and a 4.6% increase in a frontal projection. Rib coverage area was found to increase 11.7% for the spleen. Morphological changes in the organs were also observed. The liver expanded 7.8% cranially and compressed 3.4% and 5.2% in the anterior-posterior and medial-lateral directions, respectively. Similar trends were observed in the spleen and kidneys. These findings indicate that the posture of the subject has implications in computational human body model development.

Final Report for Project ''Role of Metal Bioavailability in In Situ Bioremediation of Metal and Organic Co-Contaminated Sites''; FINAL

International Nuclear Information System (INIS)

Raina M. Maier

2002-01-01

A large proportion of hazardous waste sites are co-contaminated with organics and various metals. Such co-contaminated sites are difficult to bioremediate due to the nature of the mixed contaminants. Specifically, the presence of a co-contaminating metal imposes increased stress on indigenous populations already impacted by organic contaminant stress. The overall objective of this research is to investigate the effect of varying metal bioavailability on microbial populations and biodegradation of organics to allow a better understanding of how optimize remediation of co-contaminated sites. The hypothesis for this project is that metal bioavailability is not directly correlated with metal stress imposed on microbial populations that are degrading organics in soil and that further understanding of the relationship between metal bioavailability and metal stress is required for successful treatment of sites contaminated with mixtures of organics and metals. The specific objectives to be addressed to accomplish this goal are: (1) To determine the influence of metal bioavailability in soil microcosms co-contaminated with organics and metals on degradation of the organic contaminants and on mechanisms of metal resistance and (2) To determine the efficacy of different bioremediation strategies for co-contaminated soils based on metal bioavailability

Influence of organic matter transformations on the bioavailability of heavy metals in a sludge base compost

International Nuclear Information System (INIS)

Molina, M. J.; Ingelmo, F.; Soriano, M. D.; Gallardo, A.; Lapena, L.

2009-01-01

The agricultural use of anaerobically digested sewage sludge (ADSS) as stable, mature compost implies knowing its total content in heavy metals and their bioavailability. since the chemical form of the metal in the sewage sludge-based compost depends on the effect of stabilization and maturation of the organic material during composting, 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 in a mixture of ADSS and wood chips (70:30 on wet basis) with an initial C/N ratio of 30.4, during its aerobic batch composting at 30 degree centigrade of external temperature in an open type lab-scale reactor with-out lixiviation. (Author)

Influence of organic matter transformations on the bioavailability of heavy metals in a sludge base compost

Energy Technology Data Exchange (ETDEWEB)

Molina, M. J.; Ingelmo, F.; Soriano, M. D.; Gallardo, A.; Lapena, L.

2009-07-01

The agricultural use of anaerobically digested sewage sludge (ADSS) as stable, mature compost implies knowing its total content in heavy metals and their bioavailability. since the chemical form of the metal in the sewage sludge-based compost depends on the effect of stabilization and maturation of the organic material during composting, 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 in a mixture of ADSS and wood chips (70:30 on wet basis) with an initial C/N ratio of 30.4, during its aerobic batch composting at 30 degree centigrade of external temperature in an open type lab-scale reactor with-out lixiviation. (Author)

Do heavy metals and metalloids influence the detoxification of organic xenobiotics in plants?

Science.gov (United States)

Schröder, Peter; Lyubenova, Lyudmila; Huber, Christian

2009-11-01

Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation. Typha latifolia and Phragmites australis plants for the present study were grown under greenhouse conditions in experimental ponds. A Picea abies L. suspension culture was grown in a growth chamber. Cadmium sulphate, sodium arsenate and lead chloride in concentrations from 10 to 500 microM were administered to plants. Enzymes of interest for the present study were: glutathione transferase (GST), glutathione reductase, ascorbate peroxidase and peroxidase. Measurements were performed according to published methods. GST spectrophotometric assays included the model substrates CDNB, DCNB, NBC, NBoC and the herbicide Fluorodifen. Heavy metals lead to visible stress symptoms in higher plants. Besides one long-term experiment of 72 days duration, the present study shows time and concentration-dependent plant alterations already after 24 and 72 h Cd incubation. P. abies spruce cell cultures react to CdSO(4) and Na(2)HAsO(4) with an oxidative burst, similar to that observed after pathogen attack or elicitor treatment. Cd application resulted in a reduction in GSH and GSSG contents. When a heavy metal mixture containing Na(2)HAsO(4), CdSO(4) and PbCl(2) was applied to cultures, both GSH and GSSG levels declined. Incubation with

The impact of race, income, drug abuse and dependence on health insurance coverage among US adults.

Science.gov (United States)

Wang, Nianyang; Xie, Xin

2017-06-01

Little is known about the impact of drug abuse/dependence on health insurance coverage, especially by race groups and income levels. In this study, we examine the disparities in health insurance predictors and investigate the impact of drug use (alcohol abuse/dependence, nicotine dependence, and illicit drug abuse/dependence) on lack of insurance across different race and income groups. To perform the analysis, we used insurance data (8057 uninsured and 28,590 insured individual adults) from the National Surveys on Drug Use and Health (NSDUH 2011). To analyze the likelihood of being uninsured we performed weighted binomial logistic regression analyses. The results show that the overall prevalence of lacking insurance was 19.6 %. However, race differences in lack of insurance exist, especially for Hispanics who observe the highest probability of being uninsured (38.5 %). Furthermore, we observe that the lowest income level bracket (annual income <$20,000) is associated with the highest likelihood of being uninsured (37.3 %). As the result of this investigation, we observed the following relationship between drug use and lack of insurance: alcohol abuse/dependence and nicotine dependence tend to increase the risk of lack of insurance for African Americans and whites, respectively; illicit drug use increases such risk for whites; alcohol abuse/dependence increases the likelihood of lack of insurance for the group with incomes $20,000-$49,999, whereas nicotine dependence is associated with higher probability of lack of insurance for most income groups. These findings provide some useful insights for policy makers in making decisions regarding unmet health insurance coverage.

Bridging-ligand-substitution strategy for the preparation of metal-organic polyhedra

Science.gov (United States)

Li, Jian-Rong; Zhou, Hong-Cai

2010-10-01

Metal-organic polyhedra-discrete molecular architectures constructed through the coordination of metal ions and organic linkers-have recently attracted considerable attention due to their intriguing structures, their potential for a variety of applications and their relevance to biological self-assembly. Several synthetic routes have been investigated to prepare these complexes. However, to date, these preparative methods have typically been based on the direct assembly of metal ions and organic linkers. Although these routes are convenient, it remains difficult to find suitable reaction conditions or to control the outcome of the assembly process. Here, we demonstrate a synthetic strategy based on the substitution of bridging ligands in soluble metal-organic polyhedra. The introduction of linkers with different properties from those of the initial metal-organic polyhedra can thus lead to new metal-organic polyhedra with distinct properties (including size and shape). Furthermore, partial substitution can also occur and form mixed-ligand species that may be difficult to access by means of other approaches.

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.

Translocation of heavy metals from soils into floral organs and rewards of Cucurbita pepo: Implications for plant reproductive fitness.

Science.gov (United States)

Xun, Erna; Zhang, Yanwen; Zhao, Jimin; Guo, Jixun

2017-11-01

Metals and metalloids in soil could be transferred into reproductive organs and floral rewards of hyperaccumulator plants and influence their reproductive success, yet little is known whether non-hyperaccumulator plants can translocate heavy metals from soil into their floral organs and rewards (i.e., nectar and pollen) and, if so, whether plant reproduction will be affected. In our studies, summer squash (Cucurbita pepo L. cv. Golden Apple) was exposed to heavy-metal treatments during bud stage to investigate the translocation of soil-supplemented zinc, copper, nickel and lead into its floral organs (pistil, anther and nectary) and rewards (nectar and pollen) as well as floral metal accumulation effects on its reproduction. The results showed that metals taken up by squash did translocate into its floral organs and rewards, although metal accumulation varied depending on different metal types and concentrations as well as floral organ/reward types. Mean foraging time of honey bees to each male and female flower of squash grown in metal-supplemented soils was shorter relative to that of plants grown in control soils, although the visitation rate of honeybees to both male and female flowers was not affected by metal treatments. Pollen viability, pollen removal and deposition as well as mean mass per seed produced by metal-treated squash that received pollen from plants grown in control soils decreased with elevated soil-supplemented metal concentrations. The fact that squash could translocate soil-supplemented heavy metals into floral organs and rewards indicated possible reproductive consequences caused either directly (i.e., decreasing pollen viability or seed mass) or indirectly (i.e., affecting pollinators' visitation behavior to flowers) to plant fitness. Copyright © 2017 Elsevier Inc. All rights reserved.

Application of cryptogams as monitoring organisms of metal air pollution in Denmark

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, L; Pilegaard, K; Gydesen, H

1980-01-01

A reviewing statement of the use of bryophytes and lichens as biologically monitoring organisms of metal air pollution in Denmark is given with comments on the difficulties of the different methods. On the basis of presented investigations the advantages of the application of epiphytically growing bryophytes over epigeically growing species are discussed. It is concluded that epiphytes are more effective accumulators of the metals with the highest binding affinity, e.g., Cu, Fe, Pb, than epigeically growing species. Furthermore, the specific habitat conditions for epiphytes give a higher degree of comparability between different sampling sites, although epiphytes still are dependent on the existence of a suitable phorophyte on the site.

Metal Load of the Crops Depending on Land Use, Land Management and Soil Characteristics

Science.gov (United States)

Oeztan, Sezin; Duering, Rolf-Alexander

2010-05-01

The increase of pollutant concentrations in soil and in the food chain became very important in the past few decades. Metals of different toxicities (Cd, Zn, As, Cr, Cu, Pb, Ni, Co, V, Tl) occur in soils as a result of weathering, industrial processes, fertilization and atmospheric deposition. Some of them can be absorbed by the plants due to their mobility. The transfer of metals from soil into the plants can be explained by the physicochemical characteristics of the soil such as pH-value, organic matter and clay content. Badly adapted cultivation of the agricultural soils (declining pH-value, application of unsuitable fertilizers) can enhance the mobility of the metals and by the way increase their concentrations in agricultural products. With this study, a field experiment was established and the aim is to test the relations between available metal concentrations in the soil and metal load of the plants depending on the fertilization techniques. The plants and soil samples of the reference sites were taken, heavy metal contents of the soil samples identified by Microwave Assisted Extraction (MAE) and compared to the Aqua Regia Digestion Method for confirming the methodology. For the determination of the metal content in plants, MAE was executed to the selected plant samples and for that procedure, the samples were digested with HNO3 and H2O2 in the microwave oven. Quantation of the metals in soil and in plants was done by ICP-OES Methodology. The evaluation of the first results confirmed that the metal content of the soil is strongly dependent on the properties of different fertilization variants (N,P,K) used and physicochemical characteristics of the soils. According to the fertilization variants, total metal contents of the soil are increased in the soil samples which have high amounts of N, P, K fertilization. Soils which were enforced with high P fertilization degrees had significantly higher total Cd content. Results on the Cd content of the plant samples

Current at Metal-Organic Interfaces

Science.gov (United States)

Kern, Klaus

2012-02-01

Charge transport through atomic and molecular constrictions greatly affects the operation and performance of organic electronic devices. Much of our understanding of the charge injection and extraction processes in these systems relays on our knowledge of the electronic structure at the metal-organic interface. Despite significant experimental and theoretical advances in studying charge transport in nanoscale junctions, a microscopic understanding at the single atom/molecule level is missing. In the present talk I will present our recent results to probe directly the nanocontact between single molecules and a metal electrode using scanning probe microscopy and spectroscopy. The experiments provide unprecedented microscopic details of single molecule and atom junctions and open new avenues to study quantum critical and many body phenomena at the atomic scale. Implications for energy conversion devices and carbon based nanoelectronics will also be discussed.

Emission and Dynamics of Charge Carriers in Uncoated and Organic/Metal Coated Semiconductor Nanowires

Science.gov (United States)

Kaveh Baghbadorani, Masoud

In this dissertation, the dynamics of excitons in hybrid metal/organic/nanowire structures possessing nanometer thick deposited molecular and metal films on top of InP and GaAs nanowire (NW) surfaces were investigated. Optical characterizations were carried out as a function of the semiconductor NW material, design, NW size and the type and thickness of the organic material and metal used. Hybrid organic and plasmonic semiconductor nanowire heterostructures were fabricated using organic molecular beam deposition technique. I investigated the photon emission of excitons in 150 nm diameter polytype wurtzite/zincblende InP NWs and the influence of a few ten nanometer thick organic and metal films on the emission using intensity- and temperature-dependent time-integrated and time resolved (TR) photoluminescence (PL). The plasmonic NWs were coated with an Aluminum quinoline (Alq3) interlayer and magnesium-silver (Mg0.9:Ag0.1) top layer. In addition, the nonlinear optical technique of heterodyne four-wave mixing was used (in collaboration with Prof. Wolfgang Langbein, University of Cardiff) to study incoherent and coherent carrier relaxation processes on bare nanowires on a 100 femtosecond time-scale. Alq3 covered NWs reveal a stronger emission and a longer decay time of exciton transitions indicating surface state passivation at the Alq3/NW interface. Alq3/Mg:Ag NWs reveal a strong quenching of the exciton emission which is predominantly attributed to Forster energy-transfer from excitons to plasmon oscillations in the metal cluster film. Changing the Mg:Ag to gold and the organic Alq3 spacer layer to PTCDA leads to a similar behavior, but the PL quenching is strongly increased. The observed behavior is attributed to a more continuous gold deposition leading to an increased Forster energy transfer and to a metal induced band-bending. I also investigated ensembles of bare and gold/Alq3 coated GaAs-AlGaAs-GaAs core shell NWs of 130 nm diameter. Plasmonic NWs with Au

Transformation of metal-organic framework to polymer gel by cross-linking the organic ligands preorganized in metal-organic framework.

Science.gov (United States)

Ishiwata, Takumi; Furukawa, Yuki; Sugikawa, Kouta; Kokado, Kenta; Sada, Kazuki

2013-04-10

Until now, seamless fusion of metal-organic frameworks (MOFs) and covalently cross-linked polymer gels (PG) at molecular level has been extremely rare, since these two matters have been regarded as opposite, that is, hard versus soft. In this report, we demonstrate transformation of cubic MOF crystals to PG via inner cross-linking of the organic linkers in the void space of MOF, followed by decomposition of the metal coordination. The obtained PG behaved as a polyelectrolyte gel, indicating the high content of ionic groups inside. Metal ions were well adsorbed in the PG due to its densely packed carboxylate groups. A chimera-type hybrid material consisting of MOF and PG was obtained by partial hydrolysis of resulting cross-linked MOF. The shape of resulting PG network well reflected the crystal structure of MOF employed as a template. Our results will connect the two different network materials that have been ever studied in the two different fields to provide new soft and hard hybrid materials, and the unique copolymerization in the large void space of the MOF will open a new horizon toward "ideal network polymers" never prepared before now.

Crystal Engineering of Naphthalenediimide-Based Metal-Organic Frameworks: Structure-Dependent Lithium Storage.

Science.gov (United States)

Tian, Bingbing; Ning, Guo-Hong; Gao, Qiang; Tan, Li-Min; Tang, Wei; Chen, Zhongxin; Su, Chenliang; Loh, Kian Ping

2016-11-16

Metal-organic frameworks (MOFs) possess great structural diversity because of the flexible design of linker groups and metal nodes. The structure-property correlation has been extensively investigated in areas like chiral catalysis, gas storage and absorption, water purification, energy storage, etc. However, the use of MOFs in lithium storage is hampered by stability issues, and how its porosity helps with battery performance is not well understood. Herein, through anion and thermodynamic control, we design a series of naphthalenediimide-based MOFs 1-4 that can be used for cathode materials in lithium-ion batteries (LIBs). Complexation of the N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide (DPNDI) ligand and CdX 2 (X = NO 3 - or ClO 4 - ) produces complexes MOFs 1 and 2 with a one-dimensional (1D) nonporous network and a porous, noninterpenetrated two-dimensional (2D) square-grid structure, respectively. With the DPNDI ligand and Co(NCS) 2 , a porous 1D MOF 3 as a kinetic product is obtained, while a nonporous, noninterpenetrated 2D square-grid structure MOF 4 as a thermodynamic product is formed. The performance of LIBs is largely affected by the stability and porosity of these MOFs. For instance, the initial charge-discharge curves of MOFs 1 and 2 show a specific capacity of ∼47 mA h g -1 with a capacity retention ratio of >70% during 50 cycles at 100 mA g -1 , which is much better than that of MOFs 3 and 4. The better performances are assigned to the higher stability of Cd(II) MOFs compared to that of Co(II) MOFs during the electrochemical process, according to X-ray diffraction analysis. In addition, despite having the same Cd(II) node in the framework, MOF 2 exhibits a lithium-ion diffusion coefficient (D Li ) larger than that of MOF 1 because of its higher porosity. X-ray photoelectron spectroscopy and Fourier transform infrared analysis indicate that metal nodes in these MOFs remain intact and only the DPNDI ligand undergoes the revisible redox reaction

Supercapacitors of nanocrystalline metal-organic frameworks.

Science.gov (United States)

Choi, Kyung Min; Jeong, Hyung Mo; Park, Jung Hyo; Zhang, Yue-Biao; Kang, Jeung Ku; Yaghi, Omar M

2014-07-22

The high porosity of metal-organic frameworks (MOFs) has been used to achieve exceptional gas adsorptive properties but as yet remains largely unexplored for electrochemical energy storage devices. This study shows that MOFs made as nanocrystals (nMOFs) can be doped with graphene and successfully incorporated into devices to function as supercapacitors. A series of 23 different nMOFs with multiple organic functionalities and metal ions, differing pore sizes and shapes, discrete and infinite metal oxide backbones, large and small nanocrystals, and a variety of structure types have been prepared and examined. Several members of this series give high capacitance; in particular, a zirconium MOF exhibits exceptionally high capacitance. It has the stack and areal capacitance of 0.64 and 5.09 mF cm(-2), about 6 times that of the supercapacitors made from the benchmark commercial activated carbon materials and a performance that is preserved over at least 10000 charge/discharge cycles.

Energy loss spectroscopy study of Si(111)--alkali metal interfaces at low temperatures

International Nuclear Information System (INIS)

Avci, R.

1986-01-01

Studies are made at approx.150 K under ultrahigh vacuum conditions on a wide range of alkali metal coverages on Si(111)-7 x 7. Negative second-derivative backscattered electron energy loss spectroscopy is used with 100 eV primary electrons. The interaction of the alkali metals with the silicon substrate goes through two stages as a function of alkali coverage: In the initial coverages, for less than approx.0.3 monolayer of alkali atoms, the basic reaction is that of charge transfer from the alkali atoms to the Si surface with a loss peak at approx.3.3 eV associated with the charge transfer states. The second stage of reaction: starting after the depletion of all the Si surface states: falls in a coverage range between approx.0.3 and approx.1 monolayer, in which the formation of a metallic layer with a coverage-dependent loss feature at about 2 eV is observed. At still higher coverages, multiple surface and bulk plasmon excitations and their combinations are dominant. In the overall scattering processes most of the parallel momentum (approx.3 A -1 ) is transferred to the sample during the elastic backscattering from the surface, and all the losses are essentially attributed to the forward inelastic scattering before and/or after the elastic process takes place near the metal/Si interface

The distribution of some rare metals in the process of separation of organic matter from Estonian dictyonema argillite

International Nuclear Information System (INIS)

Palvadre, R.; Ahelik, V.

1993-01-01

The distribution of rare metals Mo, U and V in the process of separation of organic matter from Maardu and Toolse argillite s is discussed. The beneficiation process of argillite consists of the hydro cycling treatment, in the course of which organic matter is separated as a light fraction, followed by direct flotation of organic matter and pyrite concentrates. Determinations of Mo and U were made by X-ray fluorescence, V by titration and pyrite by titration of iron. It can be concluded that rare metals Mo, U and V were concentrating in organic matter, their recovery in pyrite and quartz was negligible, depending on the degree of pyrite separation. The recovery of rare metals, especially that of V in the mineral phase, was more considerable in the processing of Maardu argillite, whose content of clay minerals was higher than that of Toolse argillite. 4 tabs., 6 refs

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.

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

Insight into the construction of metal-organic polyhedra: Metal-organic cubes as a case study

KAUST Repository

Al Kordi, Mohamed; Belof, Jonathan L.; Rivera, Edwin R.; Wojtas, Łukasz; Eddaoudi, 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.

Metal-phthalocyanine ordered layers on Au(110): Metal-dependent adsorption energy

Energy Technology Data Exchange (ETDEWEB)

Massimi, Lorenzo, E-mail: lorenzo.massimi@uniroma1.it; Angelucci, Marco; Gargiani, Pierluigi; Betti, Maria Grazia [Dipartimento di Fisica, Università di Roma La “Sapienza,” 00185 Roma (Italy); Montoro, Silvia [IFIS Litoral, CONICET-UNL, Laboratorio de Fisica de Superficies e Interfaces, Güemes 3450, Santa Fe (Argentina); Mariani, Carlo, E-mail: carlo.mariani@uniroma1.it [Dipartimento di Fisica, CNISM, Università di Roma La “Sapienza,” 00185 Roma (Italy)

2014-06-28

Iron-phthalocyanine and cobalt-phthalocyanine chains, assembled along the Au(110)-(1×2) reconstructed channels, present a strong interaction with the Au metallic states, via the central metal ion. X-ray photoemission spectroscopy from the metal-2p core-levels and valence band high-resolution ultraviolet photoelectron spectroscopy bring to light signatures of the interaction of the metal-phthalocyanine single-layer with gold. The charge transfer from Au to the molecule causes the emerging of a metal-2p core level component at lower binding energy with respect to that measured in the molecular thin films, while the core-levels associated to the organic macrocycle (C and N 1s) are less influenced by the adsorption, and the macrocycles stabilize the interaction, inducing a strong interface dipole. Temperature Programmed Desorption experiments and photoemission as a function of temperature allow to estimate the adsorption energy for the thin-films, mainly due to the molecule-molecule van der Waals interaction, while the FePc and CoPc single-layers remain adsorbed on the Au surface up to at least 820 K.

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.

A highly conducting organic metal derived from an organic-transistor material: benzothienobenzothiophene.

Science.gov (United States)

Kadoya, Tomofumi; Ashizawa, Minoru; Higashino, Toshiki; Kawamoto, Tadashi; Kumeta, Shohei; Matsumoto, Hidetoshi; Mori, Takehiko

2013-11-07

BTBT ([1]benzothieno[3,2-b][1]benzothiophene) is an organic semiconductor that realizes high mobility in organic transistors. Here we report that the charge-transfer (CT) salt, (BTBT)2PF6, shows a high room-temperature conductivity of 1500 S cm(-1). This compound exhibits a resistivity jump around 150 K, but when it is covered with Apiezon N grease the resistivity jump is suppressed, and the metallic conductivity is maintained down to 60 K. Owing to the very high conductivity, the ESR signal shows a significantly asymmetric Dysonian lineshape (A/B ≅ 3) even at room temperature. Since most organic conductors are based on strong electron donors, it is remarkable that such a weak electron donor as BTBT realizes a stable and highly conducting organic metal.

"Aging Out" of Dependent Coverage and the Effects on US Labor Market and Health Insurance Choices.

Science.gov (United States)

Dahlen, Heather M

2015-11-01

I examined how labor market and health insurance outcomes were affected by the loss of dependent coverage eligibility under the Patient Protection and Affordable Care Act (ACA). I used National Health Interview Survey (NHIS) data and regression discontinuity models to measure the percentage-point change in labor market and health insurance outcomes at age 26 years. My sample was restricted to unmarried individuals aged 24 to 28 years and to a period of time before the ACA's individual mandate (2011-2013). I ran models separately for men and women to determine if there were differences based on gender. Aging out of this provision increased employment among men, employer-sponsored health insurance offers for women, and reports that health insurance coverage was worse than it was 1 year previously (overall and for young women). Uninsured rates did not increase at age 26 years, but there was an increase in the purchase of non-group health coverage, indicating interest in remaining insured after age 26 years. Many young adults will turn to state and federal health insurance marketplaces for information about health coverage. Because young adults (aged 18-29 years) regularly use social media sites, these sites could be used to advertise insurance to individuals reaching their 26th birthdays.

Surface coverage of Pt atoms on PtCo nanoparticles and catalytic kinetics for oxygen reduction

Energy Technology Data Exchange (ETDEWEB)

Jiang Rongzhong, E-mail: rongzhong.jiang@us.army.mi [Sensors and Electron Devices Directorate, U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783-1197 (United States); Rong, Charles; Chu, Deryn [Sensors and Electron Devices Directorate, U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783-1197 (United States)

2011-02-01

The surface coverage of Pt atoms on PtCo nanoparticles and its effect on catalytic kinetics for oxygen reduction were investigated. The PtCo nanoparticles with different surface coverage of Pt atoms were synthesized with various methods, including normal chemical method, microemulsion synthesis, and ultrasound-assisted microemulsion. A model of Pt atoms filling into a spherical nanoparticle was proposed to explain the relationship of surface metal atoms and nanoparticle size. The catalytic activity of the PtCo nano-particles is highly dependent on the synthetic methods, even if they have the same chemical composition. The PtCo nano-particles synthesized with ultrasound-assisted microemulsion showed the highest activity, which is attributed to an increase of active surface coverage of Pt atoms on the metal nanoparticles. The rate of oxygen reduction at 0.5 V (vs. SCE) catalyzed by the PtCo synthesized with ultrasound-assisted micro-emulsion was about four times higher than that of the PtCo synthesized with normal chemical method. As demonstrated with rotating-ring disk electrode measurement, the PtCo nano-particles can catalyze oxygen 4-electron reduction to water without intermediate H{sub 2}O{sub 2} detected.

Neutron activation analysis of trace metals in the hair and organs of small animals treated chronically with Hg and Mn

International Nuclear Information System (INIS)

Ohmori, S.; Hashimoto, K.

1985-01-01

For the purpose of studying the secretion of exogenous toxic metals into hair, the relation between their concenrations in hair and in organs, and the metal shift Hg or Mn was orally administered to Guinea pigs for protracted periods. The distributions of metals in hair and organs were examined by means of neutron activation analysis. It was found that the administration of Hg at high dose resulted in abnormally high Hg levels in hair from the 2nd dosing week and in organs after 25 weeks of dosing, and in a reduced motor activity after 25 weeks of administration. There occurred metal shifts in hair as well. Administration of Mn at high doses, on the other hand, showed no such biological influences, although a dose-dependent increase of Mn in hair was detected with time. (author)

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.

Coverage-dependent adsorption and desorption of oxygen on Pd(100)

Energy Technology Data Exchange (ETDEWEB)

Dunnen, Angela den; Jacobse, Leon; Wiegman, Sandra; Juurlink, Ludo B. F., E-mail: l.juurlink@chem.leidenuniv.nl [Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, P.O. Box 9502, 2300 RA Leiden (Netherlands); Berg, Otto T. [Department of Chemistry, California State University Fresno, 2555 E. San Ramon Ave., Fresno, California 93740 (United States)

2016-06-28

We have studied the adsorption and desorption of O{sub 2} on Pd(100) by supersonic molecular beam techniques and thermal desorption spectroscopy. Adsorption measurements on the bare surface confirm that O{sub 2} initially dissociates for all kinetic energies between 56 and 380 meV and surface temperatures between 100 and 600 K via a direct mechanism. At and below 150 K, continued adsorption leads to a combined O/O{sub 2} overlayer. Dissociation of molecularly bound O{sub 2} during a subsequent temperature ramp leads to unexpected high atomic oxygen coverages, which are also obtained at high incident energy and high surface temperature. At intermediate temperatures and energies, these high final coverages are not obtained. Our results show that kinetic energy of the gas phase reactant and reaction energy dissipated during O{sub 2} dissociation on the cold surface both enable activated nucleation of high-coverage surface structures. We suggest that excitation of local substrate phonons may play a crucial role in oxygen dissociation at any coverage.

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

KAUST Repository

Alamer, Badriah

2015-01-01

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

Determination of elemental composition of metals using ambient organic mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Shiea, Christopher [Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China); Huang, Yeou-Lih [Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China); Department of Chemistry, National Sun Yat-Sen University, 70 Lien-Hai Rd, Kaohsiung 804, Taiwan (China); Cheng, Sy-Chyi; Chen, Yi-Lun [Department of Chemistry, National Sun Yat-Sen University, 70 Lien-Hai Rd, Kaohsiung 804, Taiwan (China); Shiea, Jentaie, E-mail: jetea@mail.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, 70 Lien-Hai Rd, Kaohsiung 804, Taiwan (China); Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China)

2017-05-22

Conventional inorganic mass spectrometric (MS) analysis of metals can require time-consuming and tedious sample preparation. We thus report the novel and direct characterization of metals in solid samples using an organic MS technique known as electrospray laser desorption ionization mass spectrometry (ELDI/MS). No sample pretreatment was needed, and results were rapidly obtained due to the ambient and laser-based nature of ELDI/MS. Metals from samples were desorbed and ionized by laser irradiation, after which they reacted with EDTA and then post-ionized and detected as metal-EDTA complexes. Aluminum, copper, iron, lead, nickel, and zinc from plates, foils, and coins were characterized in seconds. This study demonstrates that an ESI/MS system can be easily modified to analyze metal elements in solids by involving a chelating agent, indicating a potentially promising development in MS towards the analysis of metals using organic MS. - Highlights: • “Organic MS” was utilized as “inorganic MS” to detect metal ions in solid samples. • Element ions desorbed by laser irradiation rapidly reacted with a chelating reagent before they were detected by MS. • Elemental composition of metals was determined by this “Organic MS” method.

Determination of elemental composition of metals using ambient organic mass spectrometry

International Nuclear Information System (INIS)

Shiea, Christopher; Huang, Yeou-Lih; Cheng, Sy-Chyi; Chen, Yi-Lun; Shiea, Jentaie

2017-01-01

Conventional inorganic mass spectrometric (MS) analysis of metals can require time-consuming and tedious sample preparation. We thus report the novel and direct characterization of metals in solid samples using an organic MS technique known as electrospray laser desorption ionization mass spectrometry (ELDI/MS). No sample pretreatment was needed, and results were rapidly obtained due to the ambient and laser-based nature of ELDI/MS. Metals from samples were desorbed and ionized by laser irradiation, after which they reacted with EDTA and then post-ionized and detected as metal-EDTA complexes. Aluminum, copper, iron, lead, nickel, and zinc from plates, foils, and coins were characterized in seconds. This study demonstrates that an ESI/MS system can be easily modified to analyze metal elements in solids by involving a chelating agent, indicating a potentially promising development in MS towards the analysis of metals using organic MS. - Highlights: • “Organic MS” was utilized as “inorganic MS” to detect metal ions in solid samples. • Element ions desorbed by laser irradiation rapidly reacted with a chelating reagent before they were detected by MS. • Elemental composition of metals was determined by this “Organic MS” method.

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.

High-pressure, ambient temperature hydrogen storage in metal-organic frameworks and porous carbon

Science.gov (United States)

Beckner, Matthew; Dailly, Anne

2014-03-01

We investigated hydrogen storage in micro-porous adsorbents at ambient temperature and pressures up to 320 bar. We measured three benchmark adsorbents: two metal-organic frameworks, Cu3(1,3,5-benzenetricarboxylate)2 [Cu3(btc)2; HKUST-1] and Zn4O(1,3,5-benzenetribenzoate)2 [Zn4O(btb)2; MOF-177], and the activated carbon MSC-30. In this talk, we focus on adsorption enthalpy calculations using a single adsorption isotherm. We use the differential form of the Claussius-Clapeyron equation applied to the Dubinin-Astakhov adsorption model to calculate adsorption enthalpies. Calculation of the adsorption enthalpy in this way gives a temperature independent enthalpy of 5-7 kJ/mol at the lowest coverage for the three materials investigated. Additionally, we discuss the assumptions and corrections that must be made when calculating adsorption isotherms at high-pressure and adsorption enthalpies.

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.

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.

Linear dose dependence of ion beam mixing of metals on Si

International Nuclear Information System (INIS)

Poker, D.B.; Appleton, B.R.

1985-01-01

These experiments were conducted to determine the dose dependences of ion beam mixing of various metal-silicon couples. V/Si and Cr/Si were included because these couples were previously suspected of exhibiting a linear dose dependence. Pd/Si was chosen because it had been reported as exhibiting only the square root dependence. Samples were cut from wafers of (100) n-type Si. The samples were cleaned in organic solvents, etched in hydrofluoric acid, and rinsed with methanol before mounting in an oil-free vacuum system for thin-film deposition. Films of Au, V, Cr, or Pd were evaporated onto the Si samples with a nominal deposition rate of 10 A/s. The thicknesses were large compared with those usually used to measure ion beam mixing and were used to ensure that conditions of unlimited supply were met. Samples were mixed with Si ions ranging in energy from 300 to 375 keV, chosen to produce ion ranges that significantly exceeded the metal film depth. Si was used as the mixing ion to prevent impurity doping of the Si substrate and to exclude a background signal from the Rutherford backscattering (RBS) spectra. Samples were mixed at room temperature, with the exception of the Au/Si samples, which were mixed at liquid nitrogen temperature. The samples were alternately mixed and analyzed in situ without exposure to atmosphere between mixing doses. The compositional distributions after mixing were measured using RBS of 2.5-MeV 4 He atoms

Coverage dependent desorption dynamics of deuterium on Si(100) surfaces: interpretation with a diffusion-promoted desorption model.

Science.gov (United States)

Matsuno, T; Niida, T; Tsurumaki, H; Namiki, A

2005-01-08

We studied coverage dependence of time-of-flight (TOF) spectra of D2 molecules thermally desorbed from the D/Si(100) surface. The mean translational energies Et of desorbed D2 molecules were found to increase from 0.20+/-0.05 eV to 0.40+/-0.04 eV as the desorption coverage window was decreased from 1.0 ML> or =thetaD> or =0.9 ML to 0.2 ML> or =thetaD> or =0 ML, being consistent with the kinetics switch predicted in the interdimer mechanism. The measured TOF spectra were deconvoluted into 2H, 3H, and 4H components by a curve fitting method along the principle of detailed balance. As a result, it turned out that the desorption kinetics changes from the 4H to the 3H situation at high coverage above thetaD=0.9 ML, while the 2H desorption is dominant for a quite wide coverage region up to thetaD=0.8 ML. A dynamic desorption mechanism by which the desorption is promoted by D-atom diffusion to dangling bonds was proposed. 2005 American Institute of Physics.

Size-dependent electronic properties of metal nanostructures

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Size-dependent electronic properties of metal nanostructures. G.U. Kulkarni. Chemistry and Physics of Materials Unit. Jawaharlal Nehru Centre for Advanced Scientific Research. Bangalore, India. kulkarni@jncasr.ac.in.

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.

Bi–Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

International Nuclear Information System (INIS)

Shi, Fa-Nian; Rosa Silva, Ana; Bian, Liang

2015-01-01

A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn–Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi 2 O(1,3,5-BTC) 2 ] n (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi 4 O 2 (COO) 12 clusters which are further connected to Mn(COO) 6 fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of (4 13 .6 2 )(4 13 .6 8 )(4 16 .6 5 )(4 18 .6 10 )(4 22 .6 14 )(4 3 ) corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones. - Graphical abstract: This metal organic framework (MOF) is the essence of a 2D metal organic oxide (MOO). - Highlights: • New concept of metal organic oxide (MOO) was defined and made difference from metal organic framework. • New MOO of MOOMnBi was synthesized by hydrothermal method. • Crystal structure of MOOMnBi was determined by single crystal X-ray analysis. • The catalytic activity of MOOMnBi was studied showing reusable after 2 cycles

Coverage dependent photoelectron spectroscopy of CO chemisorption on Cu (111): evidence for two adsorption sites

International Nuclear Information System (INIS)

Jugnet, Y.; Tran, M.D.

1978-06-01

The ultraviolet photoelectron spectra (UPS) of CO adsorbed on (111) face of Cu are found to be dependent of coverage from exposure of 0.3L up to saturation. At lowest dose two intense molecular orbitals are observed at binding energies of 8.7 and 11.7 eV - phase I -. The intensity of two additional structures at 9.6 and 13.7 eV is fastly enhanced with increasing exposure - phase II -, more weakly bound, yielding at saturation coverage the complex four peak spectra usually reported for CO and Cu. We therefore reassign the levels at 11.7 and 8.7 eV to the 4SIGMA and overlap of molecular orbitals of CO adsorbed on top position and the levels at 13.7 and 9.6 eV to the same for CO adsorbed on bridge position

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.

Effects of Fe plaque and organic acids on metal uptake by wetland plants under drained and waterlogged conditions.

Science.gov (United States)

Li, W C; Deng, H; Wong, M H

2017-12-01

This study aims to assess the role of Fe plaque in metal uptake and translocation by different wetland plants and examine the effects of organic acids on metal detoxification in wetland plants. It was found that although exposed to a similar level of metals in rhizosphere soil solution, metal uptake by shoots of Cypercus flabelliformis and Panicum paludosum was greatly reduced, consequently leading to a better growth under flooded than under drained conditions. This may be related to the enhanced Fe plaque in the former, but due to the decreased root permeability in the latter under anoxic conditions. The Fe plaque on root surface has potential to sequester metals and then reduce metal concentrations and translocation in shoot tissues. However, whether the Fe plaque acts as a barrier to metal uptake and translocation may also be dependent on the root anatomy. Although metal tolerance in wetland plants mainly depends upon their metal exclusion ability, the higher-than-toxic-level of metal concentrations in some species indicates that internal metal detoxification might also exist. It was suggested that malic or citric acid in shoots of P. paludosum and C. flabelliformis may account for their internal detoxification for Zn. Copyright © 2017 Elsevier Ltd. All rights reserved.

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 ...

Temperature-dependent liquid metal flowrate control device

International Nuclear Information System (INIS)

Carlson, R.D.

1978-01-01

A temperature-dependent liquid metal flowrate control device includes a magnet and a ferromagnetic member defining therebetween a flow path for liquid metal, the ferromagnetic member being formed of a material having a curie temperature at which a change in the flow rate of the liquid metal is desired. According to the preferred embodiment the magnet is a cylindrical rod magnet axially disposed within a cylindrical member formed of a curie material and having iron pole pieces at the ends. A cylindrical iron shunt and a thin wall stainless steel barrier are disposed in the annulus between magnet and curie material. Below the curie temperature flow between steel barrier and curie material is impeded and above the curie temperature flow impedance is reduced

Rational design of metal-organic electronic devices: A computational perspective

Science.gov (United States)

Chilukuri, Bhaskar

Organic and organometallic electronic materials continue to attract considerable attention among researchers due to their cost effectiveness, high flexibility, low temperature processing conditions and the continuous emergence of new semiconducting materials with tailored electronic properties. In addition, organic semiconductors can be used in a variety of important technological devices such as solar cells, field-effect transistors (FETs), flash memory, radio frequency identification (RFID) tags, light emitting diodes (LEDs), etc. However, organic materials have thus far not achieved the reliability and carrier mobility obtainable with inorganic silicon-based devices. Hence, there is a need for finding alternative electronic materials other than organic semiconductors to overcome the problems of inferior stability and performance. In this dissertation, I research the development of new transition metal based electronic materials which due to the presence of metal-metal, metal-pi, and pi-pi interactions may give rise to superior electronic and chemical properties versus their organic counterparts. Specifically, I performed computational modeling studies on platinum based charge transfer complexes and d 10 cyclo-[M(mu-L)]3 trimers (M = Ag, Au and L = monoanionic bidentate bridging (C/N~C/N) ligand). The research done is aimed to guide experimental chemists to make rational choices of metals, ligands, substituents in synthesizing novel organometallic electronic materials. Furthermore, the calculations presented here propose novel ways to tune the geometric, electronic, spectroscopic, and conduction properties in semiconducting materials. In addition to novel material development, electronic device performance can be improved by making a judicious choice of device components. I have studied the interfaces of a p-type metal-organic semiconductor viz cyclo-[Au(mu-Pz)] 3 trimer with metal electrodes at atomic and surface levels. This work was aimed to guide the device

Bi–Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

Energy Technology Data Exchange (ETDEWEB)

Shi, Fa-Nian, E-mail: fshi@ua.pt [School of Science, Shenyang University of Technology, 110870 Shenyang (China); Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Rosa Silva, Ana [Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Bian, Liang [Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, Xinjiang (China)

2015-05-15

A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn–Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi{sub 2}O(1,3,5-BTC){sub 2}]{sub n} (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi{sub 4}O{sub 2}(COO){sub 12} clusters which are further connected to Mn(COO){sub 6} fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of (4{sup 13}.6{sup 2})(4{sup 13}.6{sup 8})(4{sup 16}.6{sup 5})(4{sup 18}.6{sup 10})(4{sup 22}.6{sup 14})(4{sup 3}) corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones. - Graphical abstract: This metal organic framework (MOF) is the essence of a 2D metal organic oxide (MOO). - Highlights: • New concept of metal organic oxide (MOO) was defined and made difference from metal organic framework. • New MOO of MOOMnBi was synthesized by hydrothermal method. • Crystal structure of MOOMnBi was determined by single crystal X-ray analysis. • The catalytic activity of MOOMnBi was studied showing reusable after 2 cycles.

Self-aligned metallization on organic semiconductor through 3D dual-layer thermal nanoimprint

International Nuclear Information System (INIS)

Jung, Y; Cheng, X

2014-01-01

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. (paper)

Association of the Affordable Care Act Dependent Coverage Provision With Prenatal Care Use and Birth Outcomes.

Science.gov (United States)

Daw, Jamie R; Sommers, Benjamin D

2018-02-13

The effect of the Affordable Care Act (ACA) dependent coverage provision on pregnancy-related health care and health outcomes is unknown. To determine whether the dependent coverage provision was associated with changes in payment for birth, prenatal care, and birth outcomes. Retrospective cohort study, using a differences-in-differences analysis of individual-level birth certificate data comparing live births among US women aged 24 to 25 years (exposure group) and women aged 27 to 28 years (control group) before (2009) and after (2011-2013) enactment of the dependent coverage provision. Results were stratified by marital status. The dependent coverage provision of the ACA, which allowed young adults to stay on their parent's health insurance until age 26 years. Primary outcomes were payment source for birth, early prenatal care (first visit in first trimester), and adequate prenatal care (a first trimester visit and 80% of expected visits). Secondary outcomes were cesarean delivery, premature birth, low birth weight, and infant neonatal intensive care unit (NICU) admission. The study population included 1 379 005 births among women aged 24-25 years (exposure group; 299 024 in 2009; 1 079 981 in 2011-2013), and 1 551 192 births among women aged 27-28 years (control group; 325 564 in 2009; 1 225 628 in 2011-2013). From 2011-2013, compared with 2009, private insurance payment for births increased in the exposure group (36.9% to 35.9% [difference, -1.0%]) compared with the control group (52.4% to 51.1% [difference, -1.3%]), adjusted difference-in-differences, 1.9 percentage points (95% CI, 1.6 to 2.1). Medicaid payment decreased in the exposure group (51.6% to 53.6% [difference, 2.0%]) compared with the control group (37.4% to 39.4% [difference, 1.9%]), adjusted difference-in-differences, -1.4 percentage points (95% CI, -1.7 to -1.2). Self-payment for births decreased in the exposure group (5.2% to 4.3% [difference, -0.9%]) compared with the

Memory Effects and Coverage Dependence of Surface Diffusion in a Model Adsorption System

DEFF Research Database (Denmark)

Vattulainen, Ilpo Tapio; Ying, S. C.; Ala-Nissila, T.

1999-01-01

in tracer and collective diffusion. We show that memory effects can be very pronounced deep inside the ordered phases and in regions close to first and second order phase transition boundaries. Particular attention is paid to the details of the time dependence of memory effects. The memory effect in tracer......We study the coverage dependence of surface diffusion coefficients for a strongly interacting adsorption system O/W(110) via Monte Carlo simulations of a lattice-gas model. In particular, we consider the nature and emergence of memory effects as contained in the corresponding correlation factors...... diffusion is found to decay following a power law after an initial transient period. This behavior persists until the hydrodynamic regime is reached, after which the memory effect decays exponentially. The time required to reach the hydrodynamical regime and the related exponential decay is strongly...

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...

On the Peculiar Molecular Shape and Size Dependence of the Dynamics of Fluids confined in a Small-Pore Metal-Organic Framework

KAUST Repository

Skarmoutsos, Ioannis

2018-05-15

Force field based-Molecular dynamics simulations were deployed to systematically explore the dynamics of confined molecules of different shapes and sizes, i.e. linear (CO2 and N2) and spherical (CH4) fluids, in a model small pore system, i.e. the Metal-Organic Framework SIFSIX-2-Cu-i. These computations unveil an unprecedented molecular symmetry dependence of the translational and rotational dynamics of fluids confined in channel-like nanoporous materials. In particular this peculiar behaviour is reflected by the extremely slow decay of the Legendre reorientational correlation functions of even-parity order for the linear fluids which is associated to jump-like orientation flips, while the spherical fluid shows a very fast decay taking place in a sub-picosecond time scale. Such a fundamental understanding is relevant to diverse disciplines such as in chemistry, physics, biology and materials science where diatomic or polyatomic molecules of different shapes/sizes diffuse through nanopores.

Heavy metal bioaccumulation in the organisms at hydrothermal fields of the Mid-Atlantic Ridge and East-Pacific Rise

International Nuclear Information System (INIS)

Demina, L.L.; Galkin, S.V.

2008-01-01

The influence of geochemical environment as well as biological parameters on the heavy metal bioaccumulation in the hydrothermal fauna at certain fields of the Mid-Atlantic ridge (MAR) and East Pacific Rise (EPR) are studied. The highest concentration of Fe, Zn, Cu, Mn, Ni, Cr, Co, Pb, Cd, Ag, Se, Sb, As, and Hg were detected in the tubes of the most thermophilic organism Alvinella caudata inhabited sulfide chimneys at 9 0 50 ' N EPR, i.e. at place where the influence of hydrothermal fluids was the maximal. Elevated heavy metals levels were typical for organs associated with the endo symbiotic bacteria activity, such as gills of specialized mussels Bathymodiolus, clams Archivestica gigas (Calyptogena magnifica), trophosome of vestimentifera Riftia, maxillipeds of shrimps Rimicaris exoculata. Inter-site (Broken Spur vs. Rainbow) comparison of the partitioning of metals within soft tissues has revealed that metal concentrations in the fauna habitats is an important albeit not the single factor that controls the metal content in the interior organs of the taxa. The external parts of mussels, such as shells, demonstrate patterns of bioaccumulation reflecting the metal concentrations in the micro-habitats. In spite of the minimal metal content was found in the mussel shells, they serve as a great reservoirs for heavy metal deposition and storage at the hydrothermal regions. For some elements a trend of heavy metal transferring through the food chains was revealed. There were no clear dependence between age of mussels and metal content (except Hg) in the soft tissues

A study on the photocatalytic reaction of the metals and organics

Energy Technology Data Exchange (ETDEWEB)

Na, Jeong Won; Cho, Young Hyun; Seong, Ki Woong; Kim, Yong Ik; Kang, Hee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-12-01

TiO{sub 2}-based photocatalytic reactions in organometallic solution the form of metal(iron and copper)-EDTA complexes in order to examine the metal removal behavior were performed. Photocatalysis technology that have the ability to remove both organics and metal can be applied to efficiently treat the radioactive organic waste in the basis of appropriate process development. 10 tabs., 21 figs. (Author).

A study on the photocatalytic reaction of the metals and organics

International Nuclear Information System (INIS)

Na, Jeong Won; Cho, Young Hyun; Seong, Ki Woong; Kim, Yong Ik; Kang, Hee

1995-12-01

TiO 2 -based photocatalytic reactions in organometallic solution the form of metal(iron and copper)-EDTA complexes in order to examine the metal removal behavior were performed. Photocatalysis technology that have the ability to remove both organics and metal can be applied to efficiently treat the radioactive organic waste in the basis of appropriate process development. 10 tabs., 21 figs. (Author)

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

Metal-ion interactions and the structural organization of Sepia eumelanin.

Science.gov (United States)

Liu, Yan; Simon, John D

2005-02-01

The structural organization of melanin granules isolated from ink sacs of Sepia officinalis was examined as a function of metal ion content by scanning electron microscopy and atomic force microscopy. Exposing Sepia melanin granules to ethelenediaminetetraacetic acid (EDTA) solution or to metal salt solutions changed the metal content in the melanin, but did not alter granular morphology. Thus ionic forces between the organic components and metal ions in melanin are not required to sustain the natural morphology once the granule is assembled. However, when aqueous suspensions of Sepia melanin granules of varying metal content are ultra-sonicated, EDTA-washed and Fe-saturated melanin samples lose material to the solution more readily than the corresponding Ca(II) and Mg(II)-loaded samples. The solubilized components are found to be 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-rich constituents. Associated with different metal ions, Na(I), Ca(II) and Mg(II) or Fe(III), these DHICA-rich entities form distinct two-dimensional aggregation structures when dried on the flat surface of mica. The data suggest multiply-charged ions play an important role in assisting or templating the assembly of the metal-free organic components to form the three-dimensional substructure distributed along the protein scaffold within the granule.

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

Do more health insurance options lead to higher wages? Evidence from states extending dependent coverage.

Science.gov (United States)

Dillender, Marcus

2014-07-01

Little is known about how health insurance affects labor market decisions for young adults. This is despite the fact that expanding coverage for people in their early 20s is an important component of the Affordable Care Act. This paper studies how having an outside source of health insurance affects wages by using variation in health insurance access that comes from states extending dependent coverage to young adults. Using American Community Survey and Census data, I find evidence that extending health insurance to young adults raises their wages. The increases in wages can be explained by increases in human capital and the increased flexibility in the labor market that comes from people no longer having to rely on their own employers for health insurance. The estimates from this paper suggest the Affordable Care Act will lead to wage increases for young adults. Copyright © 2014 Elsevier B.V. All rights reserved.

Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

Science.gov (United States)

Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

2017-01-10

A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

Investigation of buried metal-organic interface with photoelectron spectroscopy (PES)

Energy Technology Data Exchange (ETDEWEB)

Vrdoljak, Pavo; Schoell, Achim; Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik II, 97074 Wuerzburg (Germany); Umbach, Eberhard [Forschungszentrum Karlsruhe, 76021 Karlsruhe (Germany)

2008-07-01

Metal-organic interfaces are of crucial importance for electronic devices since they influence the layer morphology, the electronic structure at contacts, and the charge carrier transport. Various investigations have addressed this issue from the viewpoint of surface science, applying model systems with thin organic films on flat (single crystalline or amorphous) metal substrates. The contacts in electronic devices, however, can be very different. This is mainly due to the morphological roughness of the interface in case of a metal top contact deposited on an organic layer and the possible influence on the electronic structure. In case of real contacts also interdiffusion has to be taken into account. However, surface sensitive techniques such as photoelectron spectroscopy (PES) and atomic force microscopy (AFM) can not immediately access the buried interface. To tackle this problem we have applied and optimised a lift-off technique which allows the removal of the metal top-contact in the UHV and analyse the interface between the contact and the organic film. We present first PES and AFM results of Au contacts deposited on PTCDA layers.

Raman spectroscopy of sputtered metal-graphene and metal-oxide-graphene interfaces

Science.gov (United States)

Chen, Ching-Tzu; Gajek, Marcin; Freitag, Marcus; Kuroda, Marcelo; Perebeinos, Vasili; Raoux, Simone

2012-02-01

In this talk, we report our recent development in sputtering deposition of magnetic and non-magnetic metal and metal-oxide thin films on graphene for applications in spintronics and nanoeleoctronics. TEM and SEM images demonstrate homogeneous coverage, uniform thickness, and good crystallinity of the sputtered films. Raman spectroscopy shows that the structure of the underlying graphene is well preserved, and the spectral weight of the defect D mode is comparable to that of the e-beam evaporated samples. Most significantly, we report the first observation of graphene-enhanced surface excitations of crystalline materials. Specifically, we discover two pronounced dispersive Raman modes at the interface of graphene and the nickel-oxide and cobalt-oxide films which we attribute to the strong light absorption and high-order resonant scattering process in the graphene layer. We will present the frequency-dependent, polarization-dependent Raman data of these two modes and discuss their microscopic origin.

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

Multirate delivery of multiple therapeutic agents from metal-organic frameworks

Directory of Open Access Journals (Sweden)

Alistair C. McKinlay

2014-12-01

Full Text Available The highly porous nature of metal-organic frameworks (MOFs offers great potential for the delivery of therapeutic agents. Here, we show that highly porous metal-organic frameworks can be used to deliver multiple therapeutic agents—a biologically active gas, an antibiotic drug molecule, and an active metal ion—simultaneously but at different rates. The possibilities offered by delivery of multiple agents with different mechanisms of action and, in particular, variable timescales may allow new therapy approaches. Here, we show that the loaded MOFs are highly active against various strains of bacteria.

22 CFR 226.31 - Insurance coverage.

Science.gov (United States)

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Insurance coverage. 226.31 Section 226.31 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ADMINISTRATION OF ASSISTANCE AWARDS TO U.S. NON-GOVERNMENTAL ORGANIZATIONS Post-award Requirements Property Standards § 226.31 Insurance coverage. Recipients...

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.

Metal organic frameworks for gas storage

KAUST Repository

Alezi, Dalal; Belmabkhout, Youssef; Eddaoudi, Mohamed

2016-01-01

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

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.

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.

The effect of metal-buffer bilayer drain/source electrodes on the operational stability of the organic field effect transistors

International Nuclear Information System (INIS)

Karimi-Alavijeh, H.R.; Ehsani, A.

2015-01-01

In this paper, we have investigated experimentally the effect of different drain/source (D/S) electrodes and charge injection buffer layers on the electrical properties and operational stability of a stilbene organic field effect transistor (OFET). The results show that the organic buffer layer of copper phthalocyanine (CuPc) considerably improves the electrical properties of the transistors, but has a negligible effect on their temporal behavior. On the other hand, inorganic metal-oxide buffer layer of molybdenum oxide (MoO 3 ) drastically changes both the electrical properties and operational stability. The functionalities of this metal-oxide tightly depend on the properties of the D/S metallic electrodes. OFETs with Al/MoO 3 as the bilayer D/S electrodes have the best electrical properties: field effect mobility μ eff = 0.32 cm 2 V −1 s −1 and threshold voltage V TH = − 5 V and the transistors with Ag/MoO 3 have the longest operational stability. It was concluded that the chemical stability of the metal/metal-oxide or metal/organic interfaces of the bilayer D/S electrodes determine the operational stability of the OFETs. - Highlights: • The effect of buffer layers on the performance of the stilbene OFETs has been investigated. • Inorganic buffer layer improved the electrical and temporal behaviors simultaneously. • Organic buffer layer only changes the electrical properties. • Chemical stability of the interfaces determines the operational stability of the transistor

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells.

Science.gov (United States)

Trost, S; Becker, T; Zilberberg, K; Behrendt, A; Polywka, A; Heiderhoff, R; Görrn, P; Riedl, T

2015-01-16

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1-20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated.

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

KAUST Repository

Mohideen, Mohamed Infas Haja; Adil, Karim; Belmabkhout, Youssef; Eddaoudi, Mohamed; Bhatt, Prashant M.

2017-01-01

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.

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.

The concept of mixed organic ligands in metal-organic frameworks: design, tuning and functions.

Science.gov (United States)

Yin, Zheng; Zhou, Yan-Ling; Zeng, Ming-Hua; Kurmoo, Mohamedally

2015-03-28

The research on metal-organic frameworks (MOFs) has been developing at an extraordinary pace in its two decades of existence, as judged by the exponential growth of novel structures and the constant expansion of its applicability and research scope. A major part of the research and its success are due to the vital role of the concept of mixed organic ligands in the design, tuning and functions. This perspective, therefore, reviews the recent advances in MOFs based on this concept, which is generally based on employing a small polydentate ligand (here labelled as "nodal ligand") to form either clusters, rods or layers, which are then connected by a second ditopic linker ligand to form the framework. The structures of the materials can be grouped into the following three categories: layer-spacer (usually known as pillared-layer), rod-spacer, and cluster-spacer based MOFs. Depending on the size and geometry of the spacer ligands, interpenetrations of frameworks are occasionally found. These MOFs show a wide range of properties such as (a) crystal-to-crystal transformations upon solvent modifications, post-synthetic metal exchange or ligand reactions, (b) gas sorption, solvent selectivity and purification, (c) specific catalysis, (d) optical properties including colour change, luminescence, non-linear optic, (e) short- and long range magnetic ordering, metamagnetism and reversible ground-state modifications and (f) drug and iodine carriers with controlled release. In the following, we will highlight the importance of the above concept in the design, tuning, and functions of a selection of existing MOFs having mixed organic ligands and their associated structures and properties. The results obtained so far using this concept look very promising for fine-tuning the pore size and shape for selective adsorption and specificity in catalytic reactions, which appears to be one way to propel the advances in the application and commercialization of MOFs.

“Aging Out” of Dependent Coverage and the Effects on US Labor Market and Health Insurance Choices

Science.gov (United States)

2015-01-01

Objectives. I examined how labor market and health insurance outcomes were affected by the loss of dependent coverage eligibility under the Patient Protection and Affordable Care Act (ACA). Methods. I used National Health Interview Survey (NHIS) data and regression discontinuity models to measure the percentage-point change in labor market and health insurance outcomes at age 26 years. My sample was restricted to unmarried individuals aged 24 to 28 years and to a period of time before the ACA’s individual mandate (2011–2013). I ran models separately for men and women to determine if there were differences based on gender. Results. Aging out of this provision increased employment among men, employer-sponsored health insurance offers for women, and reports that health insurance coverage was worse than it was 1 year previously (overall and for young women). Uninsured rates did not increase at age 26 years, but there was an increase in the purchase of non–group health coverage, indicating interest in remaining insured after age 26 years. Conclusions. Many young adults will turn to state and federal health insurance marketplaces for information about health coverage. Because young adults (aged 18–29 years) regularly use social media sites, these sites could be used to advertise insurance to individuals reaching their 26th birthdays. PMID:26447916

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 ...

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

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.

PZT Films Fabricated by Metal Organic Decomposition Method

Science.gov (United States)

Sobolev, Vladimir; Ishchuk, Valeriy

2014-03-01

High quality lead zirconate titanate films have been fabricated on different substrates by metal organic decomposition method and their ferroelectric properties have been investigated. Main attention was paid to studies of the influence of the buffer layer with conditional composition Pb1.3(Zr0.5Ti0.5) O3 on the properties of Pb(Zr0.5Ti0.5) O3 films fabricated on the polycrystalline titanium and platinum substrates. It is found that in the films on the Pt substrate (with or without the buffer layer) the dependencies of the remanent polarization and the coercivity field on the number of switching cycles do not manifest fatigue up to 109 cycles. The remanent polarization dependencies for films on the Ti substrate with the buffer layer containing an excess of PbO demonstrate an fundamentally new feature that consists of a remanent polarization increase after 108 switching cycles. The increase of remanent polarization is about 50% when the number of cycles approaches 1010, while the increase of the coercivity field is small. A monotonic increase of dielectric losses has been observed in all cases.

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

Studies of high coverage oxidation of the Cu(100) surface using low energy positrons

Science.gov (United States)

Fazleev, N. G.; Maddox, W. B.; Weiss, A. H.

2012-02-01

The study of oxidation of single crystal metal surfaces is important in understanding the corrosive and catalytic processes associated with thin film metal oxides. The structures formed on oxidized transition metal surfaces vary from simple adlayers of chemisorbed oxygen to more complex structures which result from the diffusion of oxygen into subsurface regions. In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. Calculations are performed for various high coverage missing row structures ranging between 0.50 and 1.50 ML oxygen coverage. The results of calculations of positron binding energy, positron work function, and annihilation characteristics of surface trapped positrons with relevant core electrons as function of oxygen coverage are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES).

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.

Metal organic frameworks for removal of compounds from a fluid

KAUST Repository

Eddaoudi, Mohamed; Belmabkhout, Youssef

2016-01-01

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.

Synthesis of metal-organic framework films by pore diffusion method

Science.gov (United States)

Murayama, Naohiro; Nishimura, Yuki; Kajiro, Hiroshi; Kishida, Satoru; Kinoshita, Kentaro; Tottori Univ Team; Nippon Steel; Sumitomo Metal Co. Collaboration; Tottori Integrated Frontier Resaerch Center (Tifrec) Collaboration; Tottori University Electronic Display Resaerch Center (Tedrec) Collaboration

Metal-organic frameworks (MOFs) presents high controllability in designing the nano-scale pore, and this enable molecular storages, catalysts, gas sensors, gas separation membranes, and electronic devices for next-generation. Therefore, a simple method for film synthesis of MOFs compared with conventional methods [1] is strongly required. In this paper, we provide pore diffusion method, in which a substrate containing constituent metals of MOF is inserted in solution that includes only linker molecules of MOF. As a result, 2D growth of MOF was effectively enhanced, and the formation of flat and dense MOF films was attained. The growth time, t, dependence of film thickness, d, can be expressed by the relation of d = Aln(t + 1) + B, where A and B are constants. It means that ionized coppers diffuse through the pores of MOFs and the synthesis reaction proceeds at the MOF/solvent interface. We demonstrated the fabrication of a HKUST-1/Cu-TPA hetero structure by synthesizing a Cu-TPA film continuously after the growth of a HKUST-1 film on the CuOx substrate.

Metal immobilization by sludge-derived biochar: roles of mineral oxides and carbonized organic compartment.

Science.gov (United States)

Zhang, Weihua; Huang, Xinchen; Jia, Yanming; Rees, Frederic; Tsang, Daniel C W; Qiu, Rongliang; Wang, Hong

2017-04-01

Pyrolyzing sludge into biochar is a potentially promising recycling/disposal solution for municipal wastewater sludge, and the sludge-derived biochar (SDBC) presents an excellent sorbent for metal immobilization. As SDBC is composed of both mineral oxides and carbonized organic compartment, this study therefore compared the sorption behaviour of Pb and Zn on SDBC to those of individual and mixture of activated carbon (AC) and amorphous aluminium oxide (Al 2 O 3 ). Batch experiments were conducted at 25 and 45 °C, and the metal-loaded sorbents were artificially aged in the atmosphere for 1-60 days followed by additional sorption experiments. The Pb sorption was generally higher than Zn sorption, and the co-presence of Pb reduced Zn sorption on each studied sorbent. Higher sorption capacities were observed at 45 °C than 25 °C for SDBC and AC, while the opposite was shown for Al 2 O 3 , indicating the significance of temperature-dependent diffusion processes in SDBC and AC. Nevertheless, metal sorption was more selective on Al 2 O 3 that showed a greater affinity towards Pb over Zn under competition, correlating with the reducible fraction of sequential extraction. Furthermore, significant amounts of Pb and Zn were additionally sorbed on SDBC following 30-day ageing. The X-ray diffraction revealed the formation of metal-phosphate precipitates, while the X-ray photoelectron spectroscopy showed a larger quantity of metal-oxygen bonding after 30-day ageing of metal-loaded SDBC. The results may imply favourable long-term transformation and additional sorption capacity of SDBC. In conclusion, SDBC resembles the sorption characteristics of both organic and mineral sorbents in different aspects, presenting an appropriate material for metal immobilization during soil amendment.

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.

Temperature dependence of critical resolved shear stress for cubic metals

International Nuclear Information System (INIS)

Rashid, H.; Fazal-e-Aleem; Ali, M.

1996-01-01

The experimental measurements for critical resolved shear stress of various BCC and FCC metals have been explained by using Radiation Model. The temperature dependence of CRSS for different cubic metals is found to the first approximation, to upon the type of the crystal. A good agreement between experimental observations and predictions of the Radiation Model is found. (author)

A tri-metal centered metal-organic framework for solid-phase microextraction of environmental contaminants with enhanced extraction efficiency

International Nuclear Information System (INIS)

Liu, Shuqin; Xie, Lijun; Hu, Qingkun; Yang, Huangsheng; Pan, Guanrui; Zhu, Fang; Yang, Shenghong; Ouyang, Gangfeng

2017-01-01

This study presents the preparation and the characterizations of six tri-metal centered metal-organic frameworks (tM-MOFs) as solid-phase microextraction (SPME) adsorbents. Possessing different proportions of Al, Ga and In atoms in their frameworks, the tM-MOF-based SPME coatings exhibited different extraction performance towards the organic pollutants. Extraction results showed that the M4 (Al 0.593 Ga 0.167 In 0.240 (O 2 C 2 H 4 )(h 2 fipbb)) coating exhibited the best enrichment ability among six tM-MOFs. In addition, it showed better extraction efficiency towards the analytes than three single-metal centered MOFs coatings and a commercial polydimethylsiloxane (PDMS) coating. The adsorption process of the M4 coating was physical adsorption and it was mainly affected by the diffusion process of the compound from the sample to the material, which is the same with the adsorption processes of the single-metal centered MOFs coatings. Under optimal conditions (extraction time, 3 min; NaCl concentration, 25% (w/v); desorption temperature, 270 °C; extraction temperature, 30 °C), the M4 coating achieved low detection limits (0.13–0.88 ng L −1 ) and good linearity (5–2000 and 5–5000 ng L −1 ) for benzene series compounds. The repeatabilities (n = 5) for single fiber were between 4.3 and 8.1%, while the reproducibilities (n = 3) of fiber-to-fiber were in the range of 7.9–12.7%. Finally, a M4 coated SPME fiber was successfully applied to the analysis of environmental water samples with satisfactory recoveries (80.8%–119.5%). - Highlights: • Six tri-metal centered metal-organic frameworks were synthesized and characterized. • Novel SPME fibers were fabricated with silicone sealant film and tri-metal centered metal-organic frameworks crystals. • The self-made fiber exhibited excellent extraction performance to organic pollutants. • The self-made fiber was used for analysis of benzene series compounds in environmental water samples.

Hydrolytically stable fluorinated metal-organic frameworks for energy-efficient dehydration

KAUST Repository

Cadiau, Amandine; Belmabkhout, Youssef; Adil, Karim; Bhatt, Prashant; Pillai, Renjith S.; Shkurenko, Aleksander; Martineau-Corcos, Charlotte; Maurin, Guillaume; Eddaoudi, Mohamed

2017-01-01

fluorinated metal-organic framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites and fluorine moieties within the contracted square-shaped one-dimensional channel. This material selectively removed water vapor from gas

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.

Rapid, Selective Heavy Metal Removal from Water by a Metal-Organic Framework/Polydopamine Composite.

Science.gov (United States)

Sun, Daniel T; Peng, Li; Reeder, Washington S; Moosavi, Seyed Mohamad; Tiana, Davide; Britt, David K; Oveisi, Emad; Queen, Wendy L

2018-03-28

Drinking water contamination with heavy metals, particularly lead, is a persistent problem worldwide with grave public health consequences. Existing purification methods often cannot address this problem quickly and economically. Here we report a cheap, water stable metal-organic framework/polymer composite, Fe-BTC/PDA, that exhibits rapid, selective removal of large quantities of heavy metals, such as Pb 2+ and Hg 2+ , from real world water samples. In this work, Fe-BTC is treated with dopamine, which undergoes a spontaneous polymerization to polydopamine (PDA) within its pores via the Fe 3+ open metal sites. The PDA, pinned on the internal MOF surface, gains extrinsic porosity, resulting in a composite that binds up to 1634 mg of Hg 2+ and 394 mg of Pb 2+ per gram of composite and removes more than 99.8% of these ions from a 1 ppm solution, yielding drinkable levels in seconds. Further, the composite properties are well-maintained in river and seawater samples spiked with only trace amounts of lead, illustrating unprecedented selectivity. Remarkably, no significant uptake of competing metal ions is observed even when interferents, such as Na + , are present at concentrations up to 14 000 times that of Pb 2+ . The material is further shown to be resistant to fouling when tested in high concentrations of common organic interferents, like humic acid, and is fully regenerable over many cycles.

Frequency and voltage dependent electrical responses of poly(triarylamine) thin film-based organic Schottky diode

Science.gov (United States)

Anuar Mohamad, Khairul; Tak Hoh, Hang; Alias, Afishah; Ghosh, Bablu Kumar; Fukuda, Hisashi

2017-11-01

A metal-organic-metal (MOM) type Schottky diode based on poly (triarylamine) (PTAA) thin films has been fabricated by using the spin coating method. Investigation of the frequency dependent conductance-voltage (G-V-f) and capacitance-voltage (C-V-f) characteristics of the ITO/PTAA/Al MOM type diode were carried out in the frequency range from 12 Hz to 100 kHz using an LCR meter at room temperature. The frequency and bias voltage dependent electrical response were determined by admittance-based measured method in terms of an equivalent circuit model of the parallel combination of resistance and capacitance (RC circuit). Investigation revealed that the conductance is frequency and a bias voltage dependent in which conductance continuous increase as the increasing frequency, respectively. Meanwhile, the capacitance is dependent on frequency up to a certain value of frequency (100 Hz) but decreases at high frequency (1 - 10 kHz). The interface state density in the Schottky diode was determined from G-V and C-V characteristics. The interface state density has values almost constant of 2.8 x 1012 eV-1cm-2 with slightly decrease by increasing frequencies. Consequently, both series resistance and interface trap density were found to decrease with increasing frequency. The frequency dependence of the electrical responses is attributed the distribution density of interface states that could follow the alternating current (AC) signal.

Using biochar for remediation of soils contaminated with heavy metals and organic pollutants.

Science.gov (United States)

Zhang, Xiaokai; Wang, Hailong; He, Lizhi; Lu, Kouping; Sarmah, Ajit; Li, Jianwu; Bolan, Nanthi S; Pei, Jianchuan; Huang, Huagang

2013-12-01

Soil contamination with heavy metals and organic pollutants has increasingly become a serious global environmental issue in recent years. Considerable efforts have been made to remediate contaminated soils. Biochar has a large surface area, and high capacity to adsorb heavy metals and organic pollutants. Biochar can potentially be used to reduce the bioavailability and leachability of heavy metals and organic pollutants in soils through adsorption and other physicochemical reactions. Biochar is typically an alkaline material which can increase soil pH and contribute to stabilization of heavy metals. Application of biochar for remediation of contaminated soils may provide a new solution to the soil pollution problem. This paper provides an overview on the impact of biochar on the environmental fate and mobility of heavy metals and organic pollutants in contaminated soils and its implication for remediation of contaminated soils. Further research directions are identified to ensure a safe and sustainable use of biochar as a soil amendment for remediation of contaminated soils.

Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil

International Nuclear Information System (INIS)

Clistenes do Nascimento, Williams A.; Amarasiriwardena, Dula; Xing, Baoshan

2006-01-01

Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing phytoextraction of metals by Indian mustard (Brassica juncea) from multi-metal contaminated soils. Gallic and citric acids were able to induce removal of Cd, Zn, Cu, and Ni from soil without increasing the leaching risk. Net removal of these metals caused by LMWOA can be as much as synthetic chelates. A major reason for this is the lower phytotoxicity of LMWOA. Furthermore, supplying appropriate mineral nutrients increased biomass and metal removal. - Organic acids can be as efficient as synthetic chelates for use in phytoextraction of multi-metal contaminated soils

Metal ion-dependent DNAzymes and their applications as biosensors.

Science.gov (United States)

Lan, Tian; Lu, Yi

2012-01-01

Long considered to serve solely as the genetic information carrier, DNA has been shown in 1994 to be able to act as DNA catalysts capable of catalyzing a trans-esterification reaction similar to the action of ribozymes and protein enzymes. Although not yet found in nature, numerous DNAzymes have been isolated through in vitro selection for catalyzing many different types of reactions in the presence of different metal ions and thus become a new class of metalloenzymes. What remains unclear is how DNA can carry out catalysis with simpler building blocks and fewer functional groups than ribozymes and protein enzymes and how DNA can bind metal ions specifically to perform these functions. In the past two decades, many biochemical and biophysical studies have been carried out on DNAzymes, especially RNA-cleaving DNAzymes. Important insights have been gained regarding their metal-dependent activity, global folding, metal binding sites, and catalytic mechanisms for these DNAzymes. Because of their high metal ion selectivity, one of the most important practical applications for DNAzymes is metal ion detection, resulting in highly sensitive and selective fluorescent, colorimetric, and electrochemical sensors for a wide range of metal ions such as Pb(2+), UO2 2 +,[Formula: see text] including paramagnetic metal ions such as Cu(2+). This chapter summarizes recent progresses in in vitro selection of metal ion-selective DNAzymes, their biochemical and biophysical studies and sensing applications.

Small-angle X-ray scattering documents the growth of metal-organic frameworks

NARCIS (Netherlands)

Goesten, M.G.; Stavitski, I.; Juan-Alcañiz, J.; Martinez-Joaristi, A.; Petukhov, A.V.; Kapteijn, F.; Gascon, J.

2013-01-01

We present a combined in situ small- and wide-angle scattering (SAXS/WAXS) study on the crystallization of two topical metal-organic frameworks synthesized from similar metal and organic precursors: NH2-MIL-53(Al) and NH2-MIL-101(Al). A thorough analysis of SAXS data reveals the most important

Role of organic amendments on enhanced bioremediation of heavy metal(loid) contaminated soils.

Science.gov (United States)

Park, Jin Hee; Lamb, Dane; Paneerselvam, Periyasamy; Choppala, Girish; Bolan, Nanthi; Chung, Jae-Woo

2011-01-30

As land application becomes one of the important waste utilization and disposal practices, soil is increasingly being seen as a major source of metal(loid)s reaching food chain, mainly through plant uptake and animal transfer. With greater public awareness of the implications of contaminated soils on human and animal health there has been increasing interest in developing technologies to remediate contaminated sites. Bioremediation is a natural process which relies on soil microorganisms and higher plants to alter metal(loid) bioavailability and can be enhanced by addition of organic amendments to soils. Large quantities of organic amendments, such as manure compost, biosolid and municipal solid wastes are used as a source of nutrients and also as a conditioner to improve the physical properties and fertility of soils. These organic amendments that are low in metal(loid)s can be used as a sink for reducing the bioavailability of metal(loid)s in contaminated soils and sediments through their effect on the adsorption, complexation, reduction and volatilization of metal(loid)s. This review examines the mechanisms for the enhanced bioremediation of metal(loid)s by organic amendments and discusses the practical implications in relation to sequestration and bioavailability of metal(loid)s in soils. Copyright © 2010 Elsevier B.V. All rights reserved.

Chemical principles underpinning the performance of the metal-organic framework HKUST-1.

Science.gov (United States)

Hendon, Christopher H; Walsh, Aron

2015-07-15

A common feature of multi-functional metal-organic frameworks is a metal dimer in the form of a paddlewheel, as found in the structure of Cu 3 ( btc ) 2 (HKUST-1). The HKUST-1 framework demonstrates exceptional gas storage, sensing and separation, catalytic activity and, in recent studies, unprecedented ionic and electrical conductivity. These results are a promising step towards the real-world application of metal-organic materials. In this perspective, we discuss progress in the understanding of the electronic, magnetic and physical properties of HKUST-1, representative of the larger family of Cu···Cu containing metal-organic frameworks. We highlight the chemical interactions that give rise to its favourable properties, and which make this material well suited to a range of technological applications. From this analysis, we postulate key design principles for tailoring novel high-performance hybrid frameworks.

Fuel upgrading and reforming with metal organic framework

KAUST Repository

Eddaoudi, Mohamed; Belmabkhout, Youssef

2016-01-01

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

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

Energy Technology Data Exchange (ETDEWEB)

Boiteau, Rene M.; Shaw, Jared B.; Pasa Tolic, Ljiljana; Koppenaal, David W.; Jansson, Janet K.

2018-05-01

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. Even small structural differences

Marine lake as in situ laboratory for studies of organic matter influence on speciation and distribution of trace metals

Science.gov (United States)

Mlakar, Marina; Fiket, Željka; Geček, Sunčana; Cukrov, Neven; Cuculić, Vlado

2015-07-01

Karst marine lakes are unique marine systems, also recognized as in situ "laboratories" in which geochemical processes on a different scale compared to the open sea, can be observed. In this study, organic matter cycle and its impact 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 for the first time. Studied marine lake is small, isolated, shallow basin, with limited communication with the open sea. Intense spatial and seasonal variations of organic matter, dissolved and particulate (DOC, POC), and dissolved trace metals concentrations in the water column of the Lake are governed predominantly by natural processes. Enhanced oxygen consumption in the Lake during summer season, high DOC and POC concentrations and low redox potential result in occasional occurrence of anoxic conditions in the bottom layers with appearance of sulfur species. Speciation modeling 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 organic or inorganic phases, sulfides, Fe-oxyhydroxydes or biogenic calcite. The above is reflected in the composition of the sediments, which are, in addition to influence of karstic background and bathymetry of the basin, significantly affected by accumulation of detritus at the bottom of the Lake.

Heavy metal (Hg, Cd) effects on the ultrastructure of the chemoreceptor organs of the fish Alburnus alburnus

Energy Technology Data Exchange (ETDEWEB)

Hernadi, L.; Pevzner, R.; Salanki, J.

1986-01-01

The ultrastructural alterations of the olfactory organs and taste buds of the bleak were studied with scanning electron microscopy following treatment with different concentrations of mercury and cadmium. The metals were administered to the lake-water in the forms of HgCl/sub 2/ and CdCl/sub 2/. The concentrations (100 ug/1 Hg/sup + +/ and Cd/sup + +/, as well as 300 ug/1 Hg/sup + +/ and Cd/sup + +/) were kept constant. Samples were taken after exposures of 1 day, 2 days, 1 week, 2 weeks. The olfactory organs proved to be more sensitive than the taste buds to both metals upon any applied concentration and exposure times. The receptor cells of the olfactory organ showed different alterations to the different metals. The mercury treatment evoked dramatic decreases in the number of receptor cells and ciliated epithelial cells, while cadmium only brought forth unusual deformation and destruction of the receptor cells, without affecting the ciliated epithelial cells. On the taste buds mercury treatment affected the microridge system on the epithelial cells as well as the microvilliar system of the supporting and receptor cells. The effects showed duration and concentration dependency. Cadmium effects on the taste buds showed no structural alteration, only the mucous secretion increased over the surface of the taste buds.

New biodegradable organic-soluble chelating agents for simultaneous removal of heavy metals and organic pollutants from contaminated media

International Nuclear Information System (INIS)

Ullmann, Amos; Brauner, Neima; Vazana, Shlomi; Katz, Zhanna; Goikhman, Roman; Seemann, Boaz; Marom, Hanit; Gozin, Michael

2013-01-01

Highlights: • New soil remediation process using phase transition of partially miscible solvents. • Design and synthesis of new bio-degradable, organic soluble chelating agents. • Feasibility tests of the process on authentically polluted sediments and sludge. • Simultaneous removal of toxic metals and organic pollutants was demonstrated. -- Abstract: Advanced biodegradable and non-toxic organic chelators, which are soluble in organic media, were synthesized on the basis of the S,S-ethylenediamine-disuccinate (S,S-EDDS) ligand. The modifications suggested in this work include attachment of a lipophilic hydrocarbon chain (“tail”) to one or both nitrogen atoms of the S,S-EDDS. The new ligands were designed and evaluated for application in the Sediments Remediation Phase Transition Extraction (SR-PTE) process. This novel process is being developed for the simultaneous removal of both heavy metals and organic pollutants from contaminated soils, sediments or sludge. The new chelators were designed to bind various target metal ions, to promote extraction of these ions into organic solvents. Several variations of attached tails were synthesized and tested. The results for one of them, N,N′-bis-dodecyl-S,S-EDDS (C24-EDDS), showed that the metal-ligand complexes are concentrated in the organic-rich phase in the Phase Transition Extraction process (more than 80%). Preliminary applications of the SR-PTE process with the C24-EDDS ligand were conducted also on actually contaminated sludge (field samples). The extraction of five toxic metals, namely, Cd, Cu, Ni, Pb and Zn was examined. In general, the extraction performance of the new ligand was not less than that of S,S-EDDS when a sufficient ligand-to-extracted ion ratio (about 4:1 was applied

New biodegradable organic-soluble chelating agents for simultaneous removal of heavy metals and organic pollutants from contaminated media

Energy Technology Data Exchange (ETDEWEB)

Ullmann, Amos, E-mail: Ullmann@eng.tau.ac.il [Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Brauner, Neima; Vazana, Shlomi; Katz, Zhanna [Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Goikhman, Roman [The Hebrew University of Jerusalem, The Robert H. Smith, Faculty of Agriculture, Food and Environment, Rehovot (Israel); Seemann, Boaz; Marom, Hanit [School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Gozin, Michael, E-mail: cogozin@gmail.com [School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

2013-09-15

Highlights: • New soil remediation process using phase transition of partially miscible solvents. • Design and synthesis of new bio-degradable, organic soluble chelating agents. • Feasibility tests of the process on authentically polluted sediments and sludge. • Simultaneous removal of toxic metals and organic pollutants was demonstrated. -- Abstract: Advanced biodegradable and non-toxic organic chelators, which are soluble in organic media, were synthesized on the basis of the S,S-ethylenediamine-disuccinate (S,S-EDDS) ligand. The modifications suggested in this work include attachment of a lipophilic hydrocarbon chain (“tail”) to one or both nitrogen atoms of the S,S-EDDS. The new ligands were designed and evaluated for application in the Sediments Remediation Phase Transition Extraction (SR-PTE) process. This novel process is being developed for the simultaneous removal of both heavy metals and organic pollutants from contaminated soils, sediments or sludge. The new chelators were designed to bind various target metal ions, to promote extraction of these ions into organic solvents. Several variations of attached tails were synthesized and tested. The results for one of them, N,N′-bis-dodecyl-S,S-EDDS (C24-EDDS), showed that the metal-ligand complexes are concentrated in the organic-rich phase in the Phase Transition Extraction process (more than 80%). Preliminary applications of the SR-PTE process with the C24-EDDS ligand were conducted also on actually contaminated sludge (field samples). The extraction of five toxic metals, namely, Cd, Cu, Ni, Pb and Zn was examined. In general, the extraction performance of the new ligand was not less than that of S,S-EDDS when a sufficient ligand-to-extracted ion ratio (about 4:1 was applied.

Effects of humic acid and heavy metals on the sorption of polar and apolar organic pollutants onto biochars

International Nuclear Information System (INIS)

Wang, Fei; Sun, Hongwen; Ren, Xinhao; Liu, Yarui; Zhu, Hongkai; Zhang, Peng; Ren, Chao

2017-01-01

The effects of humic acid (HA) and heavy metals (Cu 2+ and Ag + ) on the sorption of polar and apolar organic pollutants onto biochars that were produced at temperatures of 200 °C (BC200) and 700 °C (BC700) were studied. Due to the plentiful polar functional groups on BC200, cationic propranolol exhibited higher levels of sorption than naphthalene on BC200 while naphthalene and propranolol showed similar sorption capacities on BC700. HA changed the characteristics of biochars and generally inhibited the sorption of target organic pollutants on biochars; however, enhancement occurred in some cases depending on the pollutants involved and their concentrations, biochars used and the addition sequences and concentrations of HA. On BC200, HA modifications mainly influenced sorption by decreasing its polarity and increasing its aromaticity, while on BC700, the surface area and pore volume greatly decreased due to the pore-blocking effects of HA. Residue dissolved HA in solution may also contribute to sorption inhibition. Complexation between polar functional groups on BC200 and heavy metals slightly enhanced the sorption of neutral naphthalene and significantly enhanced that of anionic 4-nitro-1-naphtol, while limited the sorption of cationic propranolol. Heavy metals together with their associated water molecules decreased the sorption of target chemicals on BC700 via pore-filling or pore-mouth-covering. Inhibition of heavy metals for 4-nitro-1-naphthol was found to be the weakest due to the bridge effects of heavy metals between 4-nitro-1-naphtol and BC700. The higher polarizability of Ag + led to the increase of its sorption on biochars in the presence of organic aromatic pollutants. The results of the present study shed light on the sorption mechanisms of bi-solute systems and enable us to select suitable biochar sorbents when chemicals co-exist. - Highlights: • Polar functional groups on low-temperature biochar enhanced propranolol sorption. • Humic acid

Effect of Ocean Acidification on Organic and Inorganic Speciation of Trace Metals.

Science.gov (United States)

Stockdale, Anthony; Tipping, Edward; Lofts, Stephen; Mortimer, Robert J G

2016-02-16

Rising concentrations of atmospheric carbon dioxide are causing acidification of the oceans. This results in changes to the concentrations of key chemical species such as hydroxide, carbonate and bicarbonate ions. These changes will affect the distribution of different forms of trace metals. Using IPCC data for pCO2 and pH under four future emissions scenarios (to the year 2100) we use a chemical speciation model to predict changes in the distribution of organic and inorganic forms of trace metals. Under a scenario where emissions peak after the year 2100, predicted free ion Al, Fe, Cu, and Pb concentrations increase by factors of up to approximately 21, 2.4, 1.5, and 2.0 respectively. Concentrations of organically complexed metal typically have a lower sensitivity to ocean acidification induced changes. Concentrations of organically complexed Mn, Cu, Zn, and Cd fall by up to 10%, while those of organically complexed Fe, Co, and Ni rise by up to 14%. Although modest, these changes may have significance for the biological availability of metals given the close adaptation of marine microorganisms to their environment.

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 ...

One-of-A-Kind: A Microporous Metal-Organic Framework Capable of Adsorptive Separation of Linear, Mono- and Di-branched Alkane Isomers via Temperature- and Adsorbate-Dependent Molecular Sieving

KAUST Repository

Wang, Hao

2018-03-29

Separation of alkane isomers represents a crucial process in the petrochemical industry in order to achieve high octane rating of gasoline. Herein, we report the first example of complete separation of linear, monobranched and dibranched alkane isomers by a single adsorbent. A calcium-based robust microporous metal-organic framework, Ca(H2tcpb) (tcpb = 1,2,4,5-tetrakis(4-carboxyphenyl)-benzene) exhibits unique molecular exclusion behavior which enables full separation of binary or ternary mixtures of alkane isomers into pure form of each isomerate. The successful separation of monobranched and dibranched hexane isomers will not only lead to the production of higher quality gasoline with maximum possible octane numbers but also fill the gap in the current separation technology. Exploration of separation mechanism indicates that structural flexibility and adsorbate-dependent structure change of the porous framework plays a vital role for the observed temperature-dependent molecular sieving property of the adsorbent.

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.

Modular assembly of metal-organic super-containers incorporating calixarenes

Science.gov (United States)

Wang, Zhenqiang; Dai, Feng-Rong

2018-01-16

A new strategy to design container molecules is presented. Sulfonylcalix[4]arenes, which are synthetic macrocyclic containers, are used as building blocks that are combined with various metal ions and tricarboxylate ligands to construct metal-organic `super-containers` (MOSCs). These MOSCs possess both endo and exo cavities and thus mimic the structure of viruses. The synthesis of MOSCs is highly modular, robust, and predictable.

Electrospray droplet exposure to organic vapors: metal ion removal from proteins and protein complexes.

Science.gov (United States)

DeMuth, J Corinne; McLuckey, Scott A

2015-01-20

The exposure of aqueous nanoelectrospray droplets to various organic vapors can dramatically reduce sodium adduction on protein ions in positive ion mass spectra. Volatile alcohols, such as methanol, ethanol, and isopropanol lead to a significant reduction in sodium ion adduction but are not as effective as acetonitrile, acetone, and ethyl acetate. Organic vapor exposure in the negative ion mode, on the other hand, has essentially no effect on alkali ion adduction. Evidence is presented to suggest that the mechanism by which organic vapor exposure reduces alkali ion adduction in the positive mode involves the depletion of alkali metal ions via ion evaporation of metal ions solvated with organic molecules. The early generation of metal/organic cluster ions during the droplet desolvation process results in fewer metal ions available to condense on the protein ions formed via the charged residue mechanism. These effects are demonstrated with holomyoglobin ions to illustrate that the metal ion reduction takes place without detectable protein denaturation, which might be revealed by heme loss or an increase in charge state distribution. No evidence is observed for denaturation with exposure to any of the organic vapors evaluated in this work.

Chelation in metal intoxication. V. Lowering of manganese content in poisoned rat organs

Energy Technology Data Exchange (ETDEWEB)

Tandon, S K; Mathur, A K

1976-01-01

Metal chelation has been considered useful in the management of manganese poisoning to a considerable extent. Our own studies in this direction have shown that some polyaminocarboxylic acids and a few amino acids are effective in not only removing manganese from the vital organs of experimentally poisoned animals but also in restoring certain metal induced biochemical and histological changes in such organs. Further, the success of p-aminosalicylic acid (PAS), a chemotherapeutic agent for tuberculosis, in manganese mobilization has led us to examine some other structurally related compounds together with a few other possible metal binding agents for their ability to remove excess metal from the organs, their sub-cellular fractions and blood cells of manganese administered rats and to investigate if there exists any relationship between the structure of such compounds and their metal mobilizing capacity. The present communication deals with the results of these investigations.

Frequency and voltage dependent electrical responses of poly(triarylamine thin film-based organic Schottky diode

Directory of Open Access Journals (Sweden)

Mohamad Khairul Anuar

2017-01-01

Full Text Available A metal-organic-metal (MOM type Schottky diode based on poly (triarylamine (PTAA thin films has been fabricated by using the spin coating method. Investigation of the frequency dependent conductance-voltage (G-V-f and capacitance-voltage (C-V-f characteristics of the ITO/PTAA/Al MOM type diode were carried out in the frequency range from 12 Hz to 100 kHz using an LCR meter at room temperature. The frequency and bias voltage dependent electrical response were determined by admittance-based measured method in terms of an equivalent circuit model of the parallel combination of resistance and capacitance (RC circuit. Investigation revealed that the conductance is frequency and a bias voltage dependent in which conductance continuous increase as the increasing frequency, respectively. Meanwhile, the capacitance is dependent on frequency up to a certain value of frequency (100 Hz but decreases at high frequency (1 – 10 kHz. The interface state density in the Schottky diode was determined from G-V and C-V characteristics. The interface state density has values almost constant of 2.8 x 1012 eV−1cm−2 with slightly decrease by increasing frequencies. Consequently, both series resistance and interface trap density were found to decrease with increasing frequency. The frequency dependence of the electrical responses is attributed the distribution density of interface states that could follow the alternating current (AC signal.

Computational modeling of Metal-Organic Frameworks

Science.gov (United States)

Sung, Jeffrey Chuen-Fai

In this work, the metal-organic frameworks MIL-53(Cr), DMOF-2,3-NH 2Cl, DMOF-2,5-NH2Cl, and HKUST-1 were modeled using molecular mechanics and electronic structure. The effect of electronic polarization on the adsorption of water in MIL-53(Cr) was studied using molecular dynamics simulations of water-loaded MIL-53 systems with both polarizable and non-polarizable force fields. Molecular dynamics simulations of the full systems and DFT calculations on representative framework clusters were utilized to study the difference in nitrogen adsorption between DMOF-2,3-NH2Cl and DMOF-2,5-NH 2Cl. Finally, the control of proton conduction in HKUST-1 by complexation of molecules to the Cu open metal site was investigated using the MS-EVB methodology.

Quality control considerations for size exclusion chromatography with online ICP-MS: a powerful tool for evaluating the size dependence of metal-organic matter complexation.

Science.gov (United States)

McKenzie, Erica R; Young, Thomas M

2013-01-01

Size exclusion chromatography (SEC), which separates molecules based on molecular volume, can be coupled with online inductively coupled plasma mass spectrometry (ICP-MS) to explore size-dependent metal-natural organic matter (NOM) complexation. To make effective use of this analytical dual detector system, the operator should be mindful of quality control measures. Al, Cr, Fe, Se, and Sn all exhibited columnless attenuation, which indicated unintended interactions with system components. Based on signal-to-noise ratio and peak reproducibility between duplicate analyses of environmental samples, consistent peak time and height were observed for Mg, Cl, Mn, Cu, Br, and Pb. Al, V, Fe, Co, Ni, Zn, Se, Cd, Sn, and Sb were less consistent overall, but produced consistent measurements in select samples. Ultrafiltering and centrifuging produced similar peak distributions, but glass fiber filtration produced more high molecular weight (MW) peaks. Storage in glass also produced more high MW peaks than did plastic bottles.

Highly stable [mambf6-n(o/h2o)n(ligand)2(solvent)x]n metal organic frameworks

KAUST Repository

Eddaoudi, Mohamed

2016-10-13

Provided herein are metal organic frameworks having high selectivity and stability in the present of gases and vapors including H2S, H2O, and CO2. Metal organic frameworks can comprise metal nodes and N-donor organic ligands. Further provided are methods of making metal organic frameworks.

Micronutrient metal speciation is driven by competitive organic chelation in grassland soils.

Science.gov (United States)

Boiteau, R.; Shaw, J. B.; Paša-Tolić, L.; Koppenaal, D.; Jansson, J.

2017-12-01

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population.

Studies on selected organic-metal interactions of importance in the environment

International Nuclear Information System (INIS)

Mason, Ian.

1995-10-01

This research project investigated the interaction between natural organics acids and selected metal ions. The aims of the project was to provide quantitative data on the speciation of metal ions when placed in systems containing natural organic acids. It was envisaged that such data will assist in the risk assessment of the Drigg low level waste site in Cumbria. The formation and complexing ability of these natural organic acids is discussed and the classing of these acids into high molecular weight organic acids and low molecular weight organic acids. Initial investigations used a potentiometric technique to study the interaction between nickel and europium and selected low molecular weight organic acids which were thought to occur in significant concentrations in soils and groundwaters. These experiments confirmed existing critically assessed literature values, and provided an experimental methodology for further 'in-house' measurement of such values. In addition, studies were also performed on systems containing two competing organic acids. (author)

Improving the Yule-Nielsen modified Neugebauer model by dot surface coverages depending on the ink superposition conditions

Science.gov (United States)

Hersch, Roger David; Crete, Frederique

2005-01-01

Dot gain is different when dots are printed alone, printed in superposition with one ink or printed in superposition with two inks. In addition, the dot gain may also differ depending on which solid ink the considered halftone layer is superposed. In a previous research project, we developed a model for computing the effective surface coverage of a dot according to its superposition conditions. In the present contribution, we improve the Yule-Nielsen modified Neugebauer model by integrating into it our effective dot surface coverage computation model. Calibration of the reproduction curves mapping nominal to effective surface coverages in every superposition condition is carried out by fitting effective dot surfaces which minimize the sum of square differences between the measured reflection density spectra and reflection density spectra predicted according to the Yule-Nielsen modified Neugebauer model. In order to predict the reflection spectrum of a patch, its known nominal surface coverage values are converted into effective coverage values by weighting the contributions from different reproduction curves according to the weights of the contributing superposition conditions. We analyze the colorimetric prediction improvement brought by our extended dot surface coverage model for clustered-dot offset prints, thermal transfer prints and ink-jet prints. The color differences induced by the differences between measured reflection spectra and reflection spectra predicted according to the new dot surface estimation model are quantified on 729 different cyan, magenta, yellow patches covering the full color gamut. As a reference, these differences are also computed for the classical Yule-Nielsen modified spectral Neugebauer model incorporating a single halftone reproduction curve for each ink. Taking into account dot surface coverages according to different superposition conditions considerably improves the predictions of the Yule-Nielsen modified Neugebauer model. In

Nanostructural self-organization and dynamic adaptation of metal-polymer tribosystems

Science.gov (United States)

Mashkov, Yu. K.

2017-02-01

The results of investigating the effect of nanosize modifiers of a polymer matrix on the nanostructural self-organization of polymer composites and dynamic adaptation of metal-polymer tribosystems, which considerably affect the wear resistance of polymer composite materials, have been analyzed. It has been shown that the physicochemical nanostructural self-organization processes are developed in metal-polymer tribosystems with the formation of thermotropic liquid-crystal structures of the polymer matrix, followed by the transition of the system to the stationary state with a negative feedback that ensures dynamic adaptation of the tribosystem to given operating conditions.

Size-dependent electronic properties of metal nanostructures

Indian Academy of Sciences (India)

Table of contents. Size-dependent electronic properties of metal nanostructures · Slide 2 · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16 · Slide 17 · Slide 18 · Slide 19 · Nanocrystalline film at liquid-liquid interface · Slide 21 · Slide 22.

Functional speciation of metal-dissolved organic matter complexes by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry and deconvolution analysis

International Nuclear Information System (INIS)

Laborda, Francisco; Ruiz-Begueria, Sergio; Bolea, Eduardo; Castillo, Juan R.

2009-01-01

High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry (HP-SEC-ICP-MS), in combination with deconvolution analysis, has been used to obtain multielemental qualitative and quantitative information about the distributions of metal complexes with different forms of natural dissolved organic matter (DOM). High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry chromatograms only provide continuous distributions of metals with respect to molecular masses, due to the high heterogeneity of dissolved organic matter, which consists of humic substances as well as biomolecules and other organic compounds. A functional speciation approach, based on the determination of the metals associated to different groups of homologous compounds, has been followed. Dissolved organic matter groups of homologous compounds are isolated from the aqueous samples under study and their high performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry elution profiles fitted to model Gaussian peaks, characterized by their respective retention times and peak widths. High performance size exclusion chromatography coupled to inductively coupled plasma mass spectrometry chromatograms of the samples are deconvoluted with respect to these model Gaussian peaks. This methodology has been applied to the characterization of metal-dissolved organic matter complexes in compost leachates. The most significant groups of homologous compounds involved in the complexation of metals in the compost leachates studied have been hydrophobic acids (humic and fulvic acids) and low molecular mass hydrophilic compounds. The environmental significance of these compounds is related to the higher biodegradability of the low molecular mass hydrophilic compounds and the lower mobility of humic acids. In general, the hydrophilic compounds accounted for the complexation of around 50% of the leached

Organic-inorganic perovskites containing trivalent metal halide layers: the templating influence of the organic cation layer.

Science.gov (United States)

Mitzi, D B

2000-12-25

Thin sheetlike crystals of the metal-deficient perovskites (H2AEQT)M2/3I4 [M = Bi or Sb; AEQT = 5,5"'-bis-(aminoethyl)-2,2':5',2'':5'',2'''-quaterthiophene] were formed from slowly cooled ethylene glycol/2-butanol solutions containing the bismuth(III) or antimony(III) iodide and AEQT.2HI salts. Each structure was refined in a monoclinic (C2/m) subcell, with the lattice parameters a = 39.712(13) A, b = 5.976(2) A, c = 6.043(2) A, beta = 92.238(5) degrees, and Z = 2 for M = Bi and a = 39.439(7) A, b = 5.952(1) A, c = 6.031(1) A, beta = 92.245(3) degrees, and Z = 2 for M = Sb. The trivalent metal cations locally adopt a distorted octahedral coordination, with M-I bond lengths ranging from 3.046(1) to 3.218(3) A (3.114 A average) for M = Bi and 3.012(1) to 3.153(2) A (3.073 A average) for M = Sb. The new organic-inorganic hybrids are the first members of a metal-deficient perovskite family consisting of (Mn+)2/nV(n-2)/nX4(2-) sheets, where V represents a vacancy (generally left out of the formula) and the metal cation valence, n, is greater than 2. The organic layers in the AEQT-based organic-inorganic hybrids feature edge-to-face aromatic interactions among the rigid, rodlike quaterthiophene moieties, which may help to stabilize the unusual metal-deficient layered structures.

Surfactant-thermal method to prepare two new cobalt metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Yu, Xianglin [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430074 (China); Toh, Yong Siang [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Zhao, Jun [College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, China Three Gorges University, Yichang 443002 (China); Nie, Lina [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ye, Kaiqi; Wang, Yue [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 (China); Li, Dongsheng [College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, China Three Gorges University, Yichang 443002 (China); Zhang, Qichun, E-mail: qczhang@ntu.edu.sg [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

2015-12-15

Employing surfactants as reaction media, two new metal-organic frameworks (MOFs):(HTEA){sub 3}[Co{sub 3}(BTC){sub 3}] (NTU-Z33) and (HTEA)[Co{sub 3}(HBTC){sub 2}(BTC)] (NTU-Z34) (H{sub 3}BTC=1,3,5-benzenetricarboxylic acid, TEA=trimethylamine, and NTU=Nanyang Technological University), have been successfully synthesized and fully characterized. Note that NTU-Z33 has an unusual trimeric [Co{sub 3}(COO){sub 9}] secondary building unit (SBU). Magnetic characterization suggests that both compounds have weak antiferromagnetic behaviors. Our success in preparing new crystalline Co-BTC based MOFs under different surfactant media could provide a new road to prepare new diverse MOFs through various combinations of surfactants. - Graphical abstract: Employing surfactants as reaction media, two new metal-organic frame-works (MOFs) have been successfully synthesized and magnetic study suggests that both compounds have weak antiferromagnetic behaviors. - Highlights: • Two novel metal-organic frame-works (MOFs). • Synthesis through surfactant-thermal condition. • weak antiferromagnetic behaviors for both compounds.

Surfactant-thermal method to prepare two new cobalt metal-organic frameworks

International Nuclear Information System (INIS)

Yu, Xianglin; Toh, Yong Siang; Zhao, Jun; Nie, Lina; Ye, Kaiqi; Wang, Yue; Li, Dongsheng; Zhang, Qichun

2015-01-01

Employing surfactants as reaction media, two new metal-organic frameworks (MOFs):(HTEA)_3[Co_3(BTC)_3] (NTU-Z33) and (HTEA)[Co_3(HBTC)_2(BTC)] (NTU-Z34) (H_3BTC=1,3,5-benzenetricarboxylic acid, TEA=trimethylamine, and NTU=Nanyang Technological University), have been successfully synthesized and fully characterized. Note that NTU-Z33 has an unusual trimeric [Co_3(COO)_9] secondary building unit (SBU). Magnetic characterization suggests that both compounds have weak antiferromagnetic behaviors. Our success in preparing new crystalline Co-BTC based MOFs under different surfactant media could provide a new road to prepare new diverse MOFs through various combinations of surfactants. - Graphical abstract: Employing surfactants as reaction media, two new metal-organic frame-works (MOFs) have been successfully synthesized and magnetic study suggests that both compounds have weak antiferromagnetic behaviors. - Highlights: • Two novel metal-organic frame-works (MOFs). • Synthesis through surfactant-thermal condition. • weak antiferromagnetic behaviors for both compounds.

Tip-Enhanced Raman Voltammetry: Coverage Dependence and Quantitative Modeling.

Science.gov (United States)

Mattei, Michael; Kang, Gyeongwon; Goubert, Guillaume; Chulhai, Dhabih V; Schatz, George C; Jensen, Lasse; Van Duyne, Richard P

2017-01-11

Electrochemical atomic force microscopy tip-enhanced Raman spectroscopy (EC-AFM-TERS) was employed for the first time to observe nanoscale spatial variations in the formal potential, E 0' , of a surface-bound redox couple. TERS cyclic voltammograms (TERS CVs) of single Nile Blue (NB) molecules were acquired at different locations spaced 5-10 nm apart on an indium tin oxide (ITO) electrode. Analysis of TERS CVs at different coverages was used to verify the observation of single-molecule electrochemistry. The resulting TERS CVs were fit to the Laviron model for surface-bound electroactive species to quantitatively extract the formal potential E 0' at each spatial location. Histograms of single-molecule E 0' at each coverage indicate that the electrochemical behavior of the cationic oxidized species is less sensitive to local environment than the neutral reduced species. This information is not accessible using purely electrochemical methods or ensemble spectroelectrochemical measurements. We anticipate that quantitative modeling and measurement of site-specific electrochemistry with EC-AFM-TERS will have a profound impact on our understanding of the role of nanoscale electrode heterogeneity in applications such as electrocatalysis, biological electron transfer, and energy production and storage.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

Energy Technology Data Exchange (ETDEWEB)

Hegde, Ganesh, E-mail: ghegde@purdue.edu; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard, E-mail: gekco@purdue.edu [Network for Computational Nanotechnology (NCN), Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Boykin, Timothy [Department of Electrical and Computer Engineering, University of Alabama, Huntsville, Alabama (United States)

2014-03-28

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

International Nuclear Information System (INIS)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard; Boykin, Timothy

2014-01-01

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

Science.gov (United States)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

2014-03-01

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

Metal-organic molecular device for non-volatile memory storage

International Nuclear Information System (INIS)

Radha, B.; Sagade, Abhay A.; Kulkarni, G. U.

2014-01-01

Non-volatile memory devices have been of immense research interest for their use in active memory storage in powered off-state of electronic chips. In literature, various molecules and metal compounds have been investigated in this regard. Molecular memory devices are particularly attractive as they offer the ease of storing multiple memory states in a unique way and also represent ubiquitous choice for miniaturized devices. However, molecules are fragile and thus the device breakdown at nominal voltages during repeated cycles hinders their practical applicability. Here, in this report, a synergetic combination of an organic molecule and an inorganic metal, i.e., a metal-organic complex, namely, palladium hexadecylthiolate is investigated for memory device characteristics. Palladium hexadecylthiolate following partial thermolysis is converted to a molecular nanocomposite of Pd(II), Pd(0), and long chain hydrocarbons, which is shown to exhibit non-volatile memory characteristics with exceptional stability and retention. The devices are all solution-processed and the memory action stems from filament formation across the pre-formed cracks in the nanocomposite film.

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

NARCIS (Netherlands)

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

2016-01-01

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

Time-dependent image potential at a metal surface

International Nuclear Information System (INIS)

Alducin, M.; Diez Muino, R.; Juaristi, J.I.

2003-01-01

Transient effects in the image potential induced by a point charge suddenly created in front of a metal surface are studied. The time evolution of the image potential is calculated using linear response theory. Two different time scales are defined: (i) the time required for the creation of the image potential and (ii) the time it takes to converge to its stationary value. Their dependence on the distance of the charge to the surface is discussed. The effect of the electron gas damping is also analyzed. For a typical metallic density, the order of magnitude of the creation time is 0.1 fs, whereas for a charge created close to the surface the convergence time is around 1-2 fs

Vapor phase coatings of metals and organics for laser fusion target applications

International Nuclear Information System (INIS)

Simonsic, G.A.; Powell, B.W.

Techniques for applying a variety of metal and organic coatings to 50- to 500 μm diameter glass micro-balloons are discussed. Coating thicknesses vary from 1- to 10 μm. Physical vapor deposition (PVD), chemical vapor deposition (CVD), and electrolytic and electroless plating are some of the techniques being evaluated for metal deposition. PVD and glow discharge polymerization are being used for the application of organic coatings. (U.S.)

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.

First-principles Hubbard U approach for small molecule binding in metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Mann, Gregory W., E-mail: gmann@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Mesosphere, Inc., San Francisco, California 94105 (United States); Lee, Kyuho, E-mail: kyuholee@lbl.gov [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Synopsys, Inc., Mountain View, California 94043 (United States); Cococcioni, Matteo, E-mail: matteo.cococcioni@epfl.ch [Theory and Simulation of Materials (THEOS), École Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Smit, Berend, E-mail: Berend-Smit@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Laboratory of Molecular Simulation, Institut des Sciences et Ingénierie Chimiques, Valais Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l’Industrie 17, CH-1951 Sion (Switzerland); Neaton, Jeffrey B., E-mail: jbneaton@lbl.gov [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

2016-05-07

We apply first-principles approaches with Hubbard U corrections for calculation of small molecule binding energetics to open-shell transition metal atoms in metal-organic frameworks (MOFs). Using density functional theory with van der Waals dispersion-corrected functionals, we determine Hubbard U values ab initio through an established linear response procedure for M-MOF-74, for a number of different metal centers (M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu). While our ab initio U values differ from those used in previous work, we show that they result in lattice parameters and electronic contributions to CO{sub 2}-MOF binding energies that lead to excellent agreement with experiments and previous results, yielding lattice parameters within 3%. In addition, U-dependent calculations for an example system, Co-MOF-74, suggest that the CO{sub 2} binding energy grows monotonically with the value of Hubbard U, with the binding energy shifting 4 kJ/mol (or 0.041 eV) over the range of U = 0-5.4 eV. These results provide insight into an approximate but computationally efficient means for calculation of small molecule binding energies to open-shell transition metal atoms in MOFs and suggest that the approach can be predictive with good accuracy, independent of the cations used and the availability of experimental data.

First-principles Hubbard U approach for small molecule binding in metal-organic frameworks

International Nuclear Information System (INIS)

Mann, Gregory W.; Lee, Kyuho; Cococcioni, Matteo; Smit, Berend; Neaton, Jeffrey B.

2016-01-01

We apply first-principles approaches with Hubbard U corrections for calculation of small molecule binding energetics to open-shell transition metal atoms in metal-organic frameworks (MOFs). Using density functional theory with van der Waals dispersion-corrected functionals, we determine Hubbard U values ab initio through an established linear response procedure for M-MOF-74, for a number of different metal centers (M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu). While our ab initio U values differ from those used in previous work, we show that they result in lattice parameters and electronic contributions to CO 2 -MOF binding energies that lead to excellent agreement with experiments and previous results, yielding lattice parameters within 3%. In addition, U-dependent calculations for an example system, Co-MOF-74, suggest that the CO 2 binding energy grows monotonically with the value of Hubbard U, with the binding energy shifting 4 kJ/mol (or 0.041 eV) over the range of U = 0-5.4 eV. These results provide insight into an approximate but computationally efficient means for calculation of small molecule binding energies to open-shell transition metal atoms in MOFs and suggest that the approach can be predictive with good accuracy, independent of the cations used and the availability of experimental data.

Homochiral metal-organic frameworks and their application in chromatography enantioseparations.

Science.gov (United States)

Peluso, Paola; Mamane, Victor; Cossu, Sergio

2014-10-10

The last frontier in the chiral stationary phases (CSPs) field for chromatography enantioseparations is represented by homochiral metal-organic frameworks (MOFs), a class of organic-inorganic hybrid materials built from metal-connecting nodes and organic-bridging ligands. The modular nature of these materials allows to design focused structures by combining properly metal, organic ligands and rigid polytopic spacers. Intriguingly, chiral ligands introduce molecular chirality in the MOF-network as well as homochirality in the secondary structure of materials (such as homohelicity) producing homochiral nets in a manner mimicking biopolymers (proteins, polysaccharides) which are characterized by a definite helical sense associated with the chirality of their building blocks (amino acids or sugars). Nowadays, robust and flexible materials characterized by high porosity and surface area became available by using preparative procedures typical of the so-called reticular synthesis. This review focuses on recent developments in the synthesis and applications of homochiral MOFs as supports for chromatography enantioseparations. Indeed, despite this field is in its infancy, interesting results have been produced and a critical overview of the 12 reported applications for gas chromatography (GC) and high-performance liquid chromatography (HPLC) can orient the reader approaching the field. Mechanistic aspects are shortly discussed and a view regarding future trends in this field is provided. Copyright © 2014 Elsevier B.V. All rights reserved.

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

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.

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.

Heterointerface Screening Effects between Organic Monolayers and Monolayer Transition Metal Dichalcogenides

KAUST Repository

Zheng, Yu Jie; Huang, Yu Li; Chen, Yifeng; Zhao, Weijie; Eda, Goki; Spataru, Catalin D.; Zhang, Wenjing; Chang, Yung-Huang; Li, Lain-Jong; Chi, Dongzhi; Quek, Su Ying; Wee, Andrew Thye Shen

2016-01-01

© 2016 American Chemical Society. The nature and extent of electronic screening at heterointerfaces and their consequences on energy level alignment are of profound importance in numerous applications, such as solar cells, electronics etc. The increasing availability of two-dimensional (2D) transition metal dichalcogenides (TMDs) brings additional opportunities for them to be used as interlayers in "van der Waals (vdW) heterostructures" and organic/inorganic flexible devices. These innovations raise the question of the extent to which the 2D TMDs participate actively in dielectric screening at the interface. Here we study perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) monolayers adsorbed on single-layer tungsten diselenide (WSe2), bare graphite, and Au(111) surfaces, revealing a strong dependence of the PTCDA HOMO-LUMO gap on the electronic screening effects from the substrate. The monolayer WSe2 interlayer provides substantial, but not complete, screening at the organic/inorganic interface. Our results lay a foundation for the exploitation of the complex interfacial properties of hybrid systems based on TMD materials.

Heterointerface Screening Effects between Organic Monolayers and Monolayer Transition Metal Dichalcogenides

KAUST Repository

Zheng, Yu Jie

2016-01-21

© 2016 American Chemical Society. The nature and extent of electronic screening at heterointerfaces and their consequences on energy level alignment are of profound importance in numerous applications, such as solar cells, electronics etc. The increasing availability of two-dimensional (2D) transition metal dichalcogenides (TMDs) brings additional opportunities for them to be used as interlayers in "van der Waals (vdW) heterostructures" and organic/inorganic flexible devices. These innovations raise the question of the extent to which the 2D TMDs participate actively in dielectric screening at the interface. Here we study perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) monolayers adsorbed on single-layer tungsten diselenide (WSe2), bare graphite, and Au(111) surfaces, revealing a strong dependence of the PTCDA HOMO-LUMO gap on the electronic screening effects from the substrate. The monolayer WSe2 interlayer provides substantial, but not complete, screening at the organic/inorganic interface. Our results lay a foundation for the exploitation of the complex interfacial properties of hybrid systems based on TMD materials.

Driving CO2 to a Quasi-Condensed Phase at the Interface between a Nanoparticle Surface and a Metal-Organic Framework at 1 bar and 298 K.

Science.gov (United States)

Lee, Hiang Kwee; Lee, Yih Hong; Morabito, Joseph V; Liu, Yejing; Koh, Charlynn Sher Lin; Phang, In Yee; Pedireddy, Srikanth; Han, Xuemei; Chou, Lien-Yang; Tsung, Chia-Kuang; Ling, Xing Yi

2017-08-23

We demonstrate a molecular-level observation of driving CO 2 molecules into a quasi-condensed phase on the solid surface of metal nanoparticles (NP) under ambient conditions of 1 bar and 298 K. This is achieved via a CO 2 accumulation in the interface between a metal-organic framework (MOF) and a metal NP surface formed by coating NPs with a MOF. Using real-time surface-enhanced Raman scattering spectroscopy, a >18-fold enhancement of surface coverage of CO 2 is observed at the interface. The high surface concentration leads CO 2 molecules to be in close proximity with the probe molecules on the metal surface (4-methylbenzenethiol), and transforms CO 2 molecules into a bent conformation without the formation of chemical bonds. Such linear-to-bent transition of CO 2 is unprecedented at ambient conditions in the absence of chemical bond formation, and is commonly observed only in pressurized systems (>10 5 bar). The molecular-level observation of a quasi-condensed phase induced by MOF coating could impact the future design of hybrid materials in diverse applications, including catalytic CO 2 conversion and ambient solid-gas operation.

Organization A Comprehensive System Of Insurance Coverage In The Potential Chemical And Biological Contamination Zone In Regions

Directory of Open Access Journals (Sweden)

Nina Vladimirovna Zaytseva

2014-12-01

Full Text Available The article provides a scientific rationale for an integrated approach to the provision of insurance coverage in the potential chemical and biological contamination zone. The following modern forms of chemical safety in the Russian Federation were considered: state reserve’s system, target program financing, state social insurance. The separate issue tackles the obligatory civil liability insurance for owners of dangerous objects. For improvement of the existing insurance protection system against emergency situations, risks were analyzed (shared on exogenous and endogenous. Among the exogenous risks including natural and climatic conditions of a region, its geographical arrangement, economic specialization, the seismic and terrorist risks were chosen and approaches to its solution were suggested. In endogenous risks’ group, the special focus is on wear and tear and obsolescence of hazardous chemical and biological object’s fixed assets. In case of high risk of an incident, it is suggested to increase in extent of insurance protection through self-insurance, a mutual insurance in the form of the organization of societies of a mutual insurance or the self-regulating organizations, and also development of voluntary insurance of a civil liability, both the owner of hazardous object, and regions of the Russian Federation and municipalities. The model of insurance coverage in the potential chemical and biological contamination zone is based on a differentiated approach to the danger level of the area. A matrix of adequate forms and types of insurance (required for insurance coverage of the population in the potential chemical and biological contamination zone was constructed. Proposed health risk management toolkit in the potential chemical and biological contamination zone will allow to use financial resources for chemical and biological safety in the regions more efficiently.

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...

Chinese newspaper coverage of genetically modified organisms

Directory of Open Access Journals (Sweden)

Du Li

2012-06-01

Full Text Available Abstract Background Debates persist around the world over the development and use of genetically modified organisms (GMO. News media has been shown to both reflect and influence public perceptions of health and science related debates, as well as policy development. To better understand the news coverage of GMOs in China, we analyzed the content of articles in two Chinese newspapers that relate to the development and promotion of genetically modified technologies and GMOs. Methods Searching in the Chinese National Knowledge Infrastructure Core Newspaper Database (CNKI-CND, we collected 77 articles, including news reports, comments and notes, published between January 2002 and August 2011 in two of the major Chinese newspapers: People’s Daily and Guangming Daily. We examined articles for perspectives that were discussed and/or mentioned regarding GMOs, the risks and benefits of GMOs, and the tone of news articles. Results The newspaper articles reported on 29 different kinds of GMOs. Compared with the possible risks, the benefits of GMOs were much more frequently discussed in the articles. 48.1% of articles were largely supportive of the GM technology research and development programs and the adoption of GM cottons, while 51.9% of articles were neutral on the subject of GMOs. Risks associated with GMOs were mentioned in the newspaper articles, but none of the articles expressed negative tones in regards to GMOs. Conclusion This study demonstrates that the Chinese print media is largely supportive of GMOs. It also indicates that the print media describes the Chinese government as actively pursuing national GMO research and development programs and the promotion of GM cotton usage. So far, discussion of the risks associated with GMOs is minimal in the news reports. The media, scientists, and the government should work together to ensure that science communication is accurate and balanced.

Chinese newspaper coverage of genetically modified organisms

Science.gov (United States)

2012-01-01

Background Debates persist around the world over the development and use of genetically modified organisms (GMO). News media has been shown to both reflect and influence public perceptions of health and science related debates, as well as policy development. To better understand the news coverage of GMOs in China, we analyzed the content of articles in two Chinese newspapers that relate to the development and promotion of genetically modified technologies and GMOs. Methods Searching in the Chinese National Knowledge Infrastructure Core Newspaper Database (CNKI-CND), we collected 77 articles, including news reports, comments and notes, published between January 2002 and August 2011 in two of the major Chinese newspapers: People’s Daily and Guangming Daily. We examined articles for perspectives that were discussed and/or mentioned regarding GMOs, the risks and benefits of GMOs, and the tone of news articles. Results The newspaper articles reported on 29 different kinds of GMOs. Compared with the possible risks, the benefits of GMOs were much more frequently discussed in the articles. 48.1% of articles were largely supportive of the GM technology research and development programs and the adoption of GM cottons, while 51.9% of articles were neutral on the subject of GMOs. Risks associated with GMOs were mentioned in the newspaper articles, but none of the articles expressed negative tones in regards to GMOs. Conclusion This study demonstrates that the Chinese print media is largely supportive of GMOs. It also indicates that the print media describes the Chinese government as actively pursuing national GMO research and development programs and the promotion of GM cotton usage. So far, discussion of the risks associated with GMOs is minimal in the news reports. The media, scientists, and the government should work together to ensure that science communication is accurate and balanced. PMID:22551150

Chinese newspaper coverage of genetically modified organisms.

Science.gov (United States)

Du, Li; Rachul, Christen

2012-06-08

Debates persist around the world over the development and use of genetically modified organisms (GMO). News media has been shown to both reflect and influence public perceptions of health and science related debates, as well as policy development. To better understand the news coverage of GMOs in China, we analyzed the content of articles in two Chinese newspapers that relate to the development and promotion of genetically modified technologies and GMOs. Searching in the Chinese National Knowledge Infrastructure Core Newspaper Database (CNKI-CND), we collected 77 articles, including news reports, comments and notes, published between January 2002 and August 2011 in two of the major Chinese newspapers: People's Daily and Guangming Daily. We examined articles for perspectives that were discussed and/or mentioned regarding GMOs, the risks and benefits of GMOs, and the tone of news articles. The newspaper articles reported on 29 different kinds of GMOs. Compared with the possible risks, the benefits of GMOs were much more frequently discussed in the articles. 48.1% of articles were largely supportive of the GM technology research and development programs and the adoption of GM cottons, while 51.9% of articles were neutral on the subject of GMOs. Risks associated with GMOs were mentioned in the newspaper articles, but none of the articles expressed negative tones in regards to GMOs. This study demonstrates that the Chinese print media is largely supportive of GMOs. It also indicates that the print media describes the Chinese government as actively pursuing national GMO research and development programs and the promotion of GM cotton usage. So far, discussion of the risks associated with GMOs is minimal in the news reports. The media, scientists, and the government should work together to ensure that science communication is accurate and balanced.

Simultaneous removal of metals and organic compounds from a heavily polluted soil

International Nuclear Information System (INIS)

Szpyrkowicz, L.; Radaelli, M.; Bertini, S.; Daniele, S.; Casarin, F.

2007-01-01

The paper describes the results of treatment of soil samples, deriving from a dismissed industrial site, contaminated with several metals: Hg, Ni, Co, Zn, Pb, Cu, Cr, As and organic substances. The soil was subjected to remediation based on a process in which an oxidising leaching agent was produced electrochemically in-line in an undivided electrochemical cell reactor equipped with a Ti/Pt-Ir anode and a stainless steel cathode. Leaching of the soil samples was performed under dynamic conditions using a leaching column. A subsequent regeneration of the leaching solution, which consisted in electrodeposition of metals and electro-oxidation of organic substances, was carried out in a packed-bed reactor equipped with a centrally positioned graphite rod, serving as an anode, and stainless steel three-dimensional filling as a cathode. The study was focused on how and to which extent the metals present in the soil, as organic complexes, can be solubilised and how the process rates are impacted by the solution pH and other process variables. Data obtained under non-oxidising conditions, typically adopted for leaching of metals, are compared with the performance of chlorine-enriched leaching solutions. The results obtained under various conditions are also discussed in terms of the total organic carbon (TOC) removal from the water phase

Abdominal Organ Location, Morphology, and Rib Coverage for the 5(th), 50(th), and 95(th) Percentile Males and Females in the Supine and Seated Posture using Multi-Modality Imaging.

Science.gov (United States)

Hayes, Ashley R; Gayzik, F Scott; Moreno, Daniel P; Martin, R Shayn; Stitzel, Joel D

The purpose of this study was to use data from a multi-modality image set of males and females representing the 5(th), 50(th), and 95(th) percentile (n=6) to examine abdominal organ location, morphology, and rib coverage variations between supine and seated postures. Medical images were acquired from volunteers in three image modalities including Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and upright MRI (uMRI). A manual and semi-automated segmentation method was used to acquire data and a registration technique was employed to conduct a comparative analysis between abdominal organs (liver, spleen, and kidneys) in both postures. Location of abdominal organs, defined by center of gravity movement, varied between postures and was found to be significant (p=0.002 to p=0.04) in multiple directions for each organ. In addition, morphology changes, including compression and expansion, were seen in each organ as a result of postural changes. Rib coverage, defined as the projected area of the ribs onto the abdominal organs, was measured in frontal, lateral, and posterior projections, and also varied between postures. A significant change in rib coverage between postures was measured for the spleen and right kidney (p=0.03 and p=0.02). The results indicate that posture affects the location, morphology and rib coverage area of abdominal organs and these implications should be noted in computational modeling efforts focused on a seated posture.

Characterizing time-dependent mechanics in metallic MEMS

Directory of Open Access Journals (Sweden)

Geers M.G.D.

2010-06-01

Full Text Available Experiments for characterization of time-dependent material properties in free-standing metallic microelectromechanical system (MEMS pose challenges: e.g. fabrication and handling (sub-μm sized specimens, control and measurement of sub-μN loads and sub-μm displacements over long periods and various temperatures [1]. A variety of experimental setups have been reported each having their pros and cons. One example is a micro-tensile tester with an ingenious electro-static specimen gripping system [2] aiding simple specimen design giving good results at μN and sub-μm levels, but without in-situ full-field observations. Other progressive examples assimilate the specimen, MEMS actuators and load cells on a single chip [3,4] yielding significant results at nN and nm levels with in-situ TEM/SEM observability, though not without complications: complex load actuator/sensor calibration per chip, measures to reduce fabrication failure and unfeasible cofabrication on wafers with commercial metallic MEMS. This work aims to overcome these drawbacks by developing experimental methods with high sensitivity, precision and in-situ full-field observation capabilities. Moreover, these should be applicable to simple free-standing metallic MEMS that can be co-fabricated with commercial devices. These methods will then serve in systematic studies into size-effects in time-dependent material properties. First a numeric-experimental method is developed. It characterizes bending deformation of onwafer μm-sized aluminum cantilevers. A specially designed micro-clamp is used to mechanically apply a constant precise deflection of the beam (zres <50 nm for a prolonged period, see fig. 1. After this period, the deflection by the micro-clamp is removed. Full-field height maps with the ensuing deformation are measured over time with confocal optical profilometry (COP. This yields the tip deflection as function of time with ~3 nm precision, see fig.2. To extract material

Self-organized formation of metal-carbon nanostructures by hyperthermal ion deposition

Energy Technology Data Exchange (ETDEWEB)

Hannstein, I.K.

2006-04-26

The quasi-simultaneous deposition of mass-selected hyperthermal carbon and metal ions results in a variety of interesting film morphologies, depending on the metal used and the deposition conditions. The observed features are of the order of a few nanometres and are therefore interesting for future potential applications in the various fields of nanotechnology. The present study focuses on the structural analysis of amorphous carbon films containing either copper, silver, gold, or iron using amongst others Rutherford Backscattering Spectroscopy, High Resolution Transmission Electron Microscopy, and Energy Dispersive X-Ray Spectroscopy. The film morphologies found are as follows: copper-containing films consist of copper nanoclusters with sizes ranging from about 3 to 9 nm uniformly distributed throughout the amorphous carbon matrix. The cluster size hereby rises with the copper content of the films. The silver containing films decompose into a pure amorphous carbon film with silver agglomerates at the surface. Both, the gold- and the iron-containing films show a multilayer structure of metal-rich layers with higher cluster density separated by metal-depleted amorphous carbon layers. The layer distances are of the order of up to 15 nm in the case of gold-carbon films and 7 nm in the case of iron-carbon films. The formation of theses different structures cannot be treated in the context of conventional self-organization mechanisms basing upon thermal diffusion and equilibrium thermodynamics. Instead, an ion-induced atomic transport, sputtering effects, and the stability of small metal clusters were taken into account in order to model the structure formation processes. A similar multilayer morphology was recently also reported in the literature for metal-carbon films grown by magnetron sputtering techniques. In order to investigate, whether the mechanisms are the same as in the case of the ion beam deposited films described above, first experiments were conducted

Effect of new soil metal immobilizing agents on metal toxicity to terrestrial invertebrates

Energy Technology Data Exchange (ETDEWEB)

Lock, K.; Janssen, C.R

2003-01-01

Organisms with different exposure routes should be used to simultaneously assess risks of metals in soils. - Application of 5% (w:w) novel metal immobilizing agent reduced the water soluble, the calcium chloride extracted as well as the pore water concentration of zinc in soils from Maatheide, a metal contaminated site in the northeast of Belgium. Addition of the metal immobilizing agents also eliminated acute toxicity to the potworm Enchytraeus albidus and the earthworm Eisenia fetida and chronic toxicity to the springtail Folsomia candida. Cocoon production by E. fetida, however, was still adversely affected. These differences may be explained by the species dependent routes of metal uptake: F. candida is probably mainly exposed via pore water while in E. fetida dietary exposure is probably also important. From these results it is clear that organisms with different exposure routes should be used simultaneously to assess the environmental risk of metal contaminated soils.

28 CFR 70.31 - Insurance coverage.

Science.gov (United States)

2010-07-01

... with Federal funds as provided to property owned by the recipient. Federally-owned property need not be...-PROFIT ORGANIZATIONS Post-Award Requirements Property Standards § 70.31 Insurance coverage. Recipients...

A Metal Chelating Porous Polymeric Support: The Missing Link for a Defect-free Metal-Organic Framework Composite Membrane

KAUST Repository

Barankova, Eva

2017-02-06

Since the discovery of size-selective metal-organic frameworks (MOFs), researchers have tried to incorporate these materials into gas separation membranes. Impressive gas selectivities were found, but these MOF membranes were mostly made on inorganic supports, which are generally too bulky and expensive for industrial gas separation. Forming MOF layers on porous polymer supports is industrially attractive but technically challenging. Two features to overcome these problems are described: 1) a metal chelating support polymer to bind the MOF layer, and 2) control of MOF crystal growth by contra-diffusion, aiming at a very thin nanocrystalline MOF layer. Using a metal chelating polythiosemicarbazide (PTSC) support and adjusting the metal and organic ligand concentrations carefully, a very compact ZIF-8 (ZIF=zeolitic imidazolate framework) layer was produced that displayed interference colors because of its smooth surface and extreme thinness-within the range of visible light. High performances were measured in terms of hydrogen/propane (8350) and propylene/propane (150) selectivity.

Impact of long-term organic residue recycling in agriculture on soil solution composition and trace metal leaching in soils.

Science.gov (United States)

Cambier, Philippe; Pot, Valérie; Mercier, Vincent; Michaud, Aurélia; Benoit, Pierre; Revallier, Agathe; Houot, Sabine

2014-11-15

amended plots, in spite of increased soil organic matter, factor of metal retention. Indeed, DOC, also increased by amendments, favours the mobility of Cu; whereas pH variations, depending on treatments, influence negatively the solubility of Zn. Generic adsorption functions of these variables partly explain the variations of trace metal concentrations and helped to unravel the numerous processes induced by regular amendments with organic waste products. Copyright © 2014 Elsevier B.V. All rights reserved.

Metal-organic and supramolecular architectures based on mechanically interlocked molecules

Science.gov (United States)

Fernando, Isurika Rosini

The focus of this work is on mechanically interlocked molecules (MIMs), which have unusual physicochemical and mechanical properties with potential applications in nano-scale/molecular devices and high strength materials. Rotaxanes, for example, consist of an axle-like molecule threaded through a wheel-like molecule, with bulky groups at the two ends of the axle preventing the wheel from dissociating. The position of the wheel along the axle can be switched in a controllable and reversible manner by applying external stimuli, a feature that might lead to the next generation of computers. Molecularly woven materials (MWMs), another example of molecules with mechanically interlocked features, are predicted to be unprecedentedly strong while being lightweight and flexible. With the ultimate goal of achieving control over the functioning of molecular devices in the solid state, a variety of pseudorotaxane building blocks were prepared and characterized, including a novel, rare blue-colored motif. The temperature-dependent assembly/disassembly of pseudorotaxanes was exploited for the construction of single-wavelength colorimetric temperature sensors over a 100 °C window. Pseudorotaxanes based on aromatic crown ether wheels and disubstituted 4,4'-bipyridinium axles were converted into rotaxanes upon binding to metal complexes (zinc, cadmium, mercury, copper, cobalt), and the formation of ordered crystalline arrays was studied in the solid state. The columnar organization of pseudorotaxanes by Hg2X6 2-- complexes (X = Cl, Br, I), leading to unprecedented dichroic (blue/red) rotaxane crystals, was demonstrated for the first time. From the crystal structures studied it became apparent that negatively charged metal complexes are needed for successful assembly with the positively charged pseudorotaxane units. To be able to use the more common, positively charged metal ions for rotaxane framework construction, neutral and negatively charged pseudorotaxanes were synthesized

10 CFR 600.131 - Insurance coverage.

Science.gov (United States)

2010-01-01

... provided to property owned by the recipient. Federally-owned property need not be insured unless required... Nonprofit Organizations Post-Award Requirements § 600.131 Insurance coverage. Recipients shall, at a minimum...

20 CFR 435.31 - Insurance coverage.

Science.gov (United States)

2010-04-01

... funds as provided to property owned by the recipient. Federally-owned property need not be insured... ORGANIZATIONS Post-Award Requirements Property Standards § 435.31 Insurance coverage. Recipients must, at a...

The impact of the Fermi-Dirac distribution on charge injection at metal/organic interfaces.

Science.gov (United States)

Wang, Z B; Helander, M G; Greiner, M T; Lu, Z H

2010-05-07

The Fermi level has historically been assumed to be the only energy-level from which carriers are injected at metal/semiconductor interfaces. In traditional semiconductor device physics, this approximation is reasonable as the thermal distribution of delocalized states in the semiconductor tends to dominate device characteristics. However, in the case of organic semiconductors the weak intermolecular interactions results in highly localized electronic states, such that the thermal distribution of carriers in the metal may also influence device characteristics. In this work we demonstrate that the Fermi-Dirac distribution of carriers in the metal has a much more significant impact on charge injection at metal/organic interfaces than has previously been assumed. An injection model which includes the effect of the Fermi-Dirac electron distribution was proposed. This model has been tested against experimental data and was found to provide a better physical description of charge injection. This finding indicates that the thermal distribution of electronic states in the metal should, in general, be considered in the study of metal/organic interfaces.

Insurance Coverage Policies for Personalized Medicine

Directory of Open Access Journals (Sweden)

Andrew Hresko

2012-10-01

Full Text Available Adoption of personalized medicine in practice has been slow, in part due to the lack of evidence of clinical benefit provided by these technologies. Coverage by insurers is a critical step in achieving widespread adoption of personalized medicine. Insurers consider a variety of factors when formulating medical coverage policies for personalized medicine, including the overall strength of evidence for a test, availability of clinical guidelines and health technology assessments by independent organizations. In this study, we reviewed coverage policies of the largest U.S. insurers for genomic (disease-related and pharmacogenetic (PGx tests to determine the extent that these tests were covered and the evidence basis for the coverage decisions. We identified 41 coverage policies for 49 unique testing: 22 tests for disease diagnosis, prognosis and risk and 27 PGx tests. Fifty percent (or less of the tests reviewed were covered by insurers. Lack of evidence of clinical utility appears to be a major factor in decisions of non-coverage. The inclusion of PGx information in drug package inserts appears to be a common theme of PGx tests that are covered. This analysis highlights the variability of coverage determinations and factors considered, suggesting that the adoption of personal medicine will affected by numerous factors, but will continue to be slowed due to lack of demonstrated clinical benefit.

Fabrication of metal organic framework materials using a layer-by-layer spin coating approach

KAUST Repository

Eddaoudi, Mohamed; Shekhah, Osama

2016-01-01

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.

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.

Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

International Nuclear Information System (INIS)

Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

2015-01-01

Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn_3L_3(DMF)_2 (1) and Zn_3L_3(DMA)_2(H_2O)_3 (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe"3"+ and Al"3"+ by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe"3"+. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe"3"+ or Al"3"+.

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...... calculations show that Pd clusters in UiO-66 are, at best, metastable and will aggregate into connected pore filling structures at equilibrium....

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.

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

KAUST Repository

Eddaoudi, Mohamed; Shekhah, Osama; Belmabkhout, Youssef

2016-01-01

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

A three-site Langmuir adsorption model to elucidate the temperature, pressure, and support dependence of the hydrogen coverage on supported Pt particles

NARCIS (Netherlands)

Ji, Y.; Koot, V.; van der Eerden, A.M.J.; Weckhuysen, B.M.; Koningsberger, D.C.; Ramaker, D.E.

2007-01-01

The three-site adsorption model, previously developed to describe H adsorption on small Pt particles, was used to gain insight into dependence of hydrogen coverage on temperature, pressure, and support ionicity. The three sites, in order of decreasing PtH bond strength, involve H in an atop, a

Structural and functional effects of heavy metals on the nervous system, including sense organs, of fish

DEFF Research Database (Denmark)

Baatrup, E

1991-01-01

metals are well known pollutants in the aquatic environment. Their interaction with relevant chemical stimuli may interfere with the communication between fish and environment. 5. The affinity for a number of ligands and macromolecules makes heavy metals most potent neurotoxins. 6. The present Mini......1. Today, fish in the environment are inevitably exposed to chemical pollution. Although most hazardous substances are present at concentrations far below the lethal level, they may still cause serious damage to the life processes of these animals. 2. Fish depend on an intact nervous system......, including their sense organs, for mediating relevant behaviour such as food search, predator recognition, communication and orientation. 3. Unfortunately, the nervous system is most vulnerable and injuries to its elements may dramatically change the behaviour and consequently the survival of fish. 4. Heavy...

Effects of Organics on the Adsorption and Mobility of Metal Cations in Clay Systems: Computational Molecular Modeling Approach

International Nuclear Information System (INIS)

Kalinichev, Andrey G.; Ngouana Wakou, Brice F.; Loganathan, Narasimhan

2013-01-01

Understanding and prediction of many natural and anthropogenic environmental processes ultimately depend on a fundamental understanding of the chemistry occurring at the mineral-fluid inter-faces. Clay-related minerals and natural organic matter (NOM) are ubiquitous in the environment, and metal-NOM complexation induces strong correlations between the NOM concentration in water and the capacity of clay particles to bind metals, thus affecting their speciation, solubility and toxicity in the environment. Despite significant geochemical, environmental and technological interest, the molecular-level mechanisms and dynamics of the physical and chemical processes involving NOM are not yet well understood. In this presentation we compare three different molecular dynamics (MD) computer simulations of metal-NOM complexation in aqueous solutions. The simulation results indicate that despite some obvious quantitative variations in the computed values depending on the size of the simulated system and on the parameters of the force field models used, all three simulations are quite robust and consistent. In particular, approximately 35-50% of Ca 2+ ions in all simulations are associated with the carboxylic groups of NOM at near-neutral pH. The stability of bidentate-coordinated contact ion pair complexes is also always strongly preferred. Easy association of metal cations with negatively charged NOM functional groups and negatively charged clay surfaces allows us to predict that cationic bridging could be the most probable mechanism of NOM association with clays in natural environments. New MD simulations are currently in progress to quantitatively assess these predictions on a molecular scale for nuclear waste disposal applications. New larger-scale clay models incorporate a more realistic representation of the structural and compositional disorder of natural illites and smectites and employ CLAYFF - a fully flexible general force field suitable for the molecular simulations

Highly stable [mambf6-n(o/h2o)n(ligand)2(solvent)x]n metal organic frameworks

KAUST Repository

Eddaoudi, Mohamed; Adil, Karim; Belmabkhout, Youssef; Shekhah, Osama; Bhatt, Prashant M.; Cadiau, Amandine

2016-01-01

Provided herein are metal organic frameworks having high selectivity and stability in the present of gases and vapors including H2S, H2O, and CO2. Metal organic frameworks can comprise metal nodes and N-donor organic ligands. Further provided

Dependence of ultrasound attenuation in rare earth metals on ratio of grain size and wavelength

International Nuclear Information System (INIS)

Kanevskij, I.N.; Nisnevich, M.M.; Spasskaya, A.A.; Kaz'mina, V.I.

1978-01-01

Results of investigation of dependences of ultrasound attenuation coefficient α on the ratio of grain average size D and wavelength lambda are presented. The investigations were carried out on rare earth metal samples produced by arc remelting in a vacuum furnace. It is shown that the way of α dependence curves of D/lambda for each of the rare earth metal is determined only by the D. This fact permits to use ultrasound measurement for control average diameter of the rare earth metal grain

Effects of soil water content and organic matter addition on the speciation and bioavailability of heavy metals

Energy Technology Data Exchange (ETDEWEB)

Hernandez-Soriano, Maria C., E-mail: maria.HernandezSoriano@ees.kuleuven.be [Department of Soil Science, College of Agriculture and Life Sciences, North Carolina State University, Campus Box 7619, 101 Derieux Street, 2232 Williams Hall, Raleigh, NC 27695 (United States); Jimenez-Lopez, Jose C. [Department of Biological Sciences, College of Science, Purdue University, 201 S. University Street, West Lafayette, IN 47907 (United States)

2012-04-15

The mobility and bioavailability of cadmium, copper, lead and zinc were evaluated in three soils amended with different organic materials for two moisture regimes. Agricultural and reclamation activities impose fresh inputs of organic matter on soil while intensive irrigation and rainstorm increase soil waterlogging incidence. Moreover, scarcity of irrigation water has prompted the use of greywater, which contain variable concentrations of organic compounds such as anionic surfactants. Soils added with hay, maize straw or peat at 1% w/w were irrigated, at field capacity (FC) or saturated (S), with an aqueous solution of the anionic surfactant Aerosol 22 (A22), corresponding to an addition of 200 mg C/kg soil/day. Soil solution was extracted after one month and analysed for total soluble metals, dissolved soil organic matter and UV absorbance at 254 nm. Speciation analyses were performed with WHAM VI for Cd, Cu, Pb, and Zn. For selected scenarios, metal uptake by barley was determined. Metal mobility increased for all treatments and soils (Pb > Cu > Cd {>=} Zn) compared to control assays. The increase was significantly correlated (p < 0.05) with soil organic matter solubilisation for Cd (R = 0.68), Cu (R = 0.73) and Zn (R = 0.86). Otherwise, Pb release was related to aluminium solubilisation (R = 0.75), which suggests that Pb was originally co-precipitated with Al-DOC complexes in the solid phase. The effect of A22 in metal bioavailability, determined as free ion activities (FIA), was mainly controlled by soil moisture regime. For soil 3, metal bioavailability was up to 20 times lower for soil amended with hay, peat or maize compared to soil treated only with A22. When soil was treated with A22 at FC barley yield significantly decreased (p < 0.05) for the increase of Pb (R = 0.71) and Zn (R = 0.79) concentrations in shoot, while for saturated conditions such uptake was up to 3 times lower. Overall, metal bioavailability was controlled by solubilisation of soil

Evaluation of Trichoptera as an indicator organism for environmental pollution by heavy metals

International Nuclear Information System (INIS)

Aizawa, Shoichi; Tsunoda, Kin-ichi; Akatsuka, Masayoshi; Inoue, Sadao; Akaiwa, Hideo

1994-01-01

A method of analysis for heavy metals in trichopteran larvae by AAS was established to evaluate this aquatic insect as an indicator organism for environmental pollution by heavy metals. A wet digestion method with nitric acid and hydrogen peroxide was found to be suitable for the decomposition of trichopteran larva samples. No serious variation in heavy metal contents was found in individual samples collected from one sampling point. A weak negative correlation was observed between the body length and the heavy metal contents of trichopteran larvae. In addition, the heavy metal content of trichopteran larvae seems to show a seasonal fluctuation. Trichopteran larvae in the Watarase River, which has abandoned copper and manganese mines along its upper stream, show an enriched heavy metal content as compared with those in other non-polluted rivers. Moreover, this aquatic insect in the Kiryu River also shows enrichment of manganese due to abandoned manganese mines situated upstream. These facts suggest that the trichopteran larva in a useful indicator organism for environmental pollution by heavy metals. (author)

Fresh organic matter of municipal solid waste enhances phytoextraction of heavy metals from contaminated soil

Energy Technology Data Exchange (ETDEWEB)

Salati, S.; Quadri, G.; Tambone, F. [Dipartimento di Produzione Vegetale, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy); Adani, F., E-mail: fabrizio.adani@unimi.i [Dipartimento di Produzione Vegetale, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy)

2010-05-15

In this study, the ability of the organic fraction of municipal solid wastes (OFMSW) to enhance heavy metal uptake of maize shoots compared with ethylenediamine disuccinic acid (EDDS) was tested on soil contaminated with heavy metals. Soils treated with OFMSW and EDDS significantly increased the concentration of heavy metals in maize shoots (increments of 302%, 66%, 184%, 169%, and 23% for Cr, Cu, Ni, Zn, and Pb with respect to the control and increments of 933%, 482%, 928%, 428%, and 5551% for soils treated with OFMSW and EDDS, respectively). In soil treated with OFMSW, metal uptake was favored because of the high presence of dissolved organic matter (DOM) (41.6x than soil control) that exhibited ligand properties because of the high presence of carboxylic acids. Because of the toxic effect of EDDS on maize plants, soil treated with OFMSW achieved the highest extraction of total heavy metals. - Organic fraction of MSW affects the bioavailability of heavy metals in soil.

Fresh organic matter of municipal solid waste enhances phytoextraction of heavy metals from contaminated soil

International Nuclear Information System (INIS)

Salati, S.; Quadri, G.; Tambone, F.; Adani, F.

2010-01-01

In this study, the ability of the organic fraction of municipal solid wastes (OFMSW) to enhance heavy metal uptake of maize shoots compared with ethylenediamine disuccinic acid (EDDS) was tested on soil contaminated with heavy metals. Soils treated with OFMSW and EDDS significantly increased the concentration of heavy metals in maize shoots (increments of 302%, 66%, 184%, 169%, and 23% for Cr, Cu, Ni, Zn, and Pb with respect to the control and increments of 933%, 482%, 928%, 428%, and 5551% for soils treated with OFMSW and EDDS, respectively). In soil treated with OFMSW, metal uptake was favored because of the high presence of dissolved organic matter (DOM) (41.6x than soil control) that exhibited ligand properties because of the high presence of carboxylic acids. Because of the toxic effect of EDDS on maize plants, soil treated with OFMSW achieved the highest extraction of total heavy metals. - Organic fraction of MSW affects the bioavailability of heavy metals in soil.

Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

DEFF Research Database (Denmark)

Hansen, Christian Rein; Sørensen, Thomas Just; Glyvradal, Magni

2009-01-01

By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir-Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 Å titanium and 100 Å aluminum....... By comparison of XR data for the five-layer Pb2+ arachidate LB film before and after vapor deposition of the Ti/Al top electrode, a detailed account of the structural damage to the organic film at the buried metal-molecule interface is obtained. We find that the organized structure of the two topmost LB layers...

Simple and accurate model for voltage-dependent resistance of metallic carbon nanotube interconnects: An ab initio study

International Nuclear Information System (INIS)

Yamacli, Serhan; Avci, Mutlu

2009-01-01

In this work, development of a voltage dependent resistance model for metallic carbon nanotubes is aimed. Firstly, the resistance of metallic carbon nanotube interconnects are obtained from ab initio simulations and then the voltage dependence of the resistance is modeled through regression. Self-consistent non-equilibrium Green's function formalism combined with density functional theory is used for calculating the voltage dependent resistance of metallic carbon nanotubes. It is shown that voltage dependent resistances of carbon nanotubes can be accurately modeled as a polynomial function which enables rapid integration of carbon nanotube interconnect models into electronic design automation tools.

Metal-Organic Framework-Derived Materials for Sodium Energy Storage.

Science.gov (United States)

Zou, Guoqiang; Hou, Hongshuai; Ge, Peng; Huang, Zhaodong; Zhao, Ganggang; Yin, Dulin; Ji, Xiaobo

2018-01-01

Recently, sodium-ion batteries (SIBs) are extensively explored and are regarded as one of the most promising alternatives to lithium-ion batteries for electrochemical energy conversion and storage, owing to the abundant raw material resources, low cost, and similar electrochemical behavior of elemental sodium compared to lithium. Metal-organic frameworks (MOFs) have attracted enormous attention due to their high surface areas, tunable structures, and diverse applications in drug delivery, gas storage, and catalysis. Recently, there has been an escalating interest in exploiting MOF-derived materials as anodes for sodium energy storage due to their fast mass transport resulting from their highly porous structures and relatively simple preparation methods originating from in situ thermal treatment processes. In this Review, the recent progress of the sodium-ion storage performances of MOF-derived materials, including MOF-derived porous carbons, metal oxides, metal oxide/carbon nanocomposites, and other materials (e.g., metal phosphides, metal sulfides, and metal selenides), as SIB anodes is systematically and completely presented and discussed. Moreover, the current challenges and perspectives of MOF-derived materials in electrochemical energy storage are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Occurrence of antibiotic and metal resistance in bacteria from organs of river fish

International Nuclear Information System (INIS)

Pathak, S.P.; Gopal, K.

2005-01-01

Bacterial populations in some organs, viz., liver, spleen, kidney, gill, and arborescent organ of the catfish Clarias batrachus were enumerated followed by determination of resistance for antibiotics and metals. The total viable counts in these organs, observed, were 2.24x10 4 , 2.08x10 4 , 1.44x10 4 , 1.23x10 4 , and 6.40x10 3 colony-forming units/mL, respectively. The random bacterial isolates from these fish organs showed resistance in decreasing order for colistin (98%), ampicillin (82%), gentamycin (34%), carbenicillin (28%), tetracyline (20%), streptomycin (12%), and ciprofloxacin (02%). Most of the isolates exhibited an increasing order of tolerance for the metals (μg/mL) copper (100), lead (200), manganese (400), cadmium (200), and chromium (50), with minimum inhibitory concentration (MIC) ranging from <50 to 1600 μg/mL. These observations indicate that the significant occurrence of bacterial population in organs of fish with high incidence of resistance for antibiotics and metals may pose risk to fish fauna and public health

Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

Energy Technology Data Exchange (ETDEWEB)

Wilczek, Grazyna [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Babczynska, Agnieszka [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Augustyniak, Maria [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Migula, Pawel [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland)]. E-mail: migula@us.edu.pl

2004-12-01

We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex.

Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

International Nuclear Information System (INIS)

Wilczek, Grazyna; Babczynska, Agnieszka; Augustyniak, Maria; Migula, Pawel

2004-01-01

We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex

Influence of Organic Matter - Mineral Interfacial Reactions on Metal(loid) Speciation and Bioaccessibility

Science.gov (United States)

Chorover, J.; Kong, S.; Root, R. A.; Thomas, A.

2015-12-01

Bioaccessibility of contaminant metals in geomedia is often measured on the basis of kinetic release to solution during in vitro reaction with biofluid simulants. We postulate that development of a predictive-mechanistic understanding of bioaccessibility requires knowledge of metal(loid) molecular speciation upon sample introduction, as well as its change over the course of the in vitro reaction. Our results - including data from batch, column, mesocosm and field studies pertaining to arsenic, lead, and zinc contaminated materials - indicate the strong influence of organic matter and associated biological activity on metal(loid) speciation in mine tailings and related model systems. Furthermore, presence/absence of organic matter during bioassays affects the kinetics of metal(loid) release into biofluid simulants through multiple mechanisms.

Directional dependence of the threshold displacement energies in metal oxides

Science.gov (United States)

Cowen, Benjamin J.; El-Genk, Mohamed S.

2017-12-01

Molecular dynamics (MD) simulations are performed to investigate the directional dependence and the values of the threshold energies (TDEs) for the displacements of the oxygen and metal atoms and for producing stable Frenkel pairs in five metal oxides of Cr2O3, Al2O3, TiO2, SiO2, and MgO. The TDEs for the Frenkel pairs and atoms displacement are calculated in 66 crystallographic directions, on both the anion and cation sublattices. The performed simulations are for metal and oxygen PKA energies up to 350 and 400 eV, respectively. The calculated probability distributions for the atoms displacement and average number of Frenkel pairs produced in the different oxides are compared. The results revealed unique symmetrical patterns of the TDEs for the displacement of the atoms and the formation of stable Frenkel pairs, confirming the strong dependence on the direction and the crystalline structure of the oxides. Results also showed that the formation of stable Frenkel pairs is associated with the displacements of the PKAs and/or of the SKAs. The probabilities of the TDEs for the displacement of the oxygen and metal PKAs are consistently lower than those of the atoms in the crystal. In SiO2, TDEs for the displacement of oxygen and metal atoms and those for the formation of stable Frenkel pairs are the lowest, while those in TiO2 are among the highest. The results for Cr2O3 and Al2O3, which have the same crystal structure, are similar. The calculated TDEs for MgO, Al2O3 and TiO2 are generally in good agreement with the experimental values and the probability distributions of the TDEs for the PKAs in TiO2 are in good agreement with reported MD simulation results.

Hydrogen adsorption in metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Senkovska, Irena; Kaskel, Stefan [Department of Inorganic Chemistry, Technical University, Dresden (Germany)

2008-07-01

Metal-Organic Frameworks (MOFs) have recently received considerable attention because of their high specific micropore volume and the ability to store gas molecules exceeding the storage capacity of traditional adsorbents. A variety of differences in the MOFs structures makes it difficult to analyze the influence of different factors on hydrogen uptake capabilities in MOFs. We have investigated the influence of the minor structural changes of the MOFs on their hydrogen storage capacity. The influence of the incorporated metal was shown for following isostructural compounds: Cu{sub 3}(BTC){sub 2} (BTC=1,3,5-benzenetricarboxylate) and Mo{sub 3}(BTC){sub 2}; Zn{sub 2}(BDC){sub 2}DABCO and Co{sub 2}(BDC){sub 2}DABCO (BDC=1,4-benzenedicarboxylate, DABCO=1,4-diazabicyclo[2.2.2]octane). Our research interest is directed also towards the discovery of new MOFs, as well as adjusting the pore dimensions of MOFs, using different building blocks, solvent and solvent mixtures, in order to improve gas uptake and adsorption properties. Magnesium-based MOFs were found with the same network topology, very small pore size and selective adsorption behaviour. They show a guest-induced reversible structure transformation due to the flexibility of the Mg{sub 3}-cluster and the organic linkers. This effect could be used for fitting the pore sizes and for the increase of gas sorption capability in Mg contained MOFs after all. The hydrogen adsorption was also studied in several Al-based IRMOFs.

Liquid metal-organic frameworks

Science.gov (United States)

Gaillac, Romain; Pullumbi, Pluton; Beyer, Kevin A.; Chapman, Karena W.; Keen, David A.; Bennett, Thomas D.; Coudert, François-Xavier

2017-11-01

Metal-organic frameworks (MOFs) are a family of chemically diverse materials, with applications in a wide range of fields, covering engineering, physics, chemistry, biology and medicine. Until recently, research has focused almost entirely on crystalline structures, yet now a clear trend is emerging, shifting the emphasis onto disordered states, including `defective by design’ crystals, as well as amorphous phases such as glasses and gels. Here we introduce a strongly associated MOF liquid, obtained by melting a zeolitic imidazolate framework. We combine in situ variable temperature X-ray, ex situ neutron pair distribution function experiments, and first-principles molecular dynamics simulations to study the melting phenomenon and the nature of the liquid obtained. We demonstrate from structural, dynamical, and thermodynamical information that the chemical configuration, coordinative bonding, and porosity of the parent crystalline framework survive upon formation of the MOF liquid.

Effects of soil water content and organic matter addition on the speciation and bioavailability of heavy metals

International Nuclear Information System (INIS)

Hernandez-Soriano, Maria C.; Jimenez-Lopez, Jose C.

2012-01-01

The mobility and bioavailability of cadmium, copper, lead and zinc were evaluated in three soils amended with different organic materials for two moisture regimes. Agricultural and reclamation activities impose fresh inputs of organic matter on soil while intensive irrigation and rainstorm increase soil waterlogging incidence. Moreover, scarcity of irrigation water has prompted the use of greywater, which contain variable concentrations of organic compounds such as anionic surfactants. Soils added with hay, maize straw or peat at 1% w/w were irrigated, at field capacity (FC) or saturated (S), with an aqueous solution of the anionic surfactant Aerosol 22 (A22), corresponding to an addition of 200 mg C/kg soil/day. Soil solution was extracted after one month and analysed for total soluble metals, dissolved soil organic matter and UV absorbance at 254 nm. Speciation analyses were performed with WHAM VI for Cd, Cu, Pb, and Zn. For selected scenarios, metal uptake by barley was determined. Metal mobility increased for all treatments and soils (Pb > Cu > Cd ≥ Zn) compared to control assays. The increase was significantly correlated (p < 0.05) with soil organic matter solubilisation for Cd (R = 0.68), Cu (R = 0.73) and Zn (R = 0.86). Otherwise, Pb release was related to aluminium solubilisation (R = 0.75), which suggests that Pb was originally co-precipitated with Al–DOC complexes in the solid phase. The effect of A22 in metal bioavailability, determined as free ion activities (FIA), was mainly controlled by soil moisture regime. For soil 3, metal bioavailability was up to 20 times lower for soil amended with hay, peat or maize compared to soil treated only with A22. When soil was treated with A22 at FC barley yield significantly decreased (p < 0.05) for the increase of Pb (R = 0.71) and Zn (R = 0.79) concentrations in shoot, while for saturated conditions such uptake was up to 3 times lower. Overall, metal bioavailability was controlled by solubilisation of soil

Protecting group and switchable pore-discriminating adsorption properties of a hydrophilic-hydrophobic metal-organic framework.

Science.gov (United States)

Mohideen, M Infas H; Xiao, Bo; Wheatley, Paul S; McKinlay, Alistair C; Li, Yang; Slawin, Alexandra M Z; Aldous, David W; Cessford, Naomi F; Düren, Tina; Zhao, Xuebo; Gill, Rachel; Thomas, K Mark; Griffin, John M; Ashbrook, Sharon E; Morris, Russell E

2011-04-01

Formed by linking metals or metal clusters through organic linkers, metal-organic frameworks are a class of solids with structural and chemical properties that mark them out as candidates for many emerging gas storage, separation, catalysis and biomedical applications. Important features of these materials include their high porosity and their flexibility in response to chemical or physical stimuli. Here, a copper-based metal-organic framework has been prepared in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during synthesis to produce a solid with two different channel systems, lined by hydrophilic and hydrophobic surfaces, respectively. The material reacts differently to gases or vapours of dissimilar chemistry, some stimulating subtle framework flexibility or showing kinetic adsorption effects. Adsorption can be switched between the two channels by judicious choice of the conditions. The monoesterified linker is recoverable in quantitative yield, demonstrating possible uses of metal-organic frameworks in molecular synthetic chemistry as 'protecting groups' to accomplish selective transformations that are difficult using standard chemistry techniques.

Contrary interfacial exciton dissociation at metal/organic interface in regular and reverse configuration organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Bo; Wu, Zhenghui; Tam, Hoi Lam; Zhu, Furong, E-mail: frzhu@hkbu.edu.hk [Department of Physics, Institute of Advanced Materials, and Institute of Research and Continuing Education (Shenzhen), Hong Kong Baptist University, 224 Waterloo Road, Kowloon Tong, NT (Hong Kong)

2014-09-08

An opposite interfacial exciton dissociation behavior at the metal (Al)/organic cathode interface in regular and inverted organic solar cells (OSCs) was analyzed using transient photocurrent measurements. It is found that Al/organic contact in regular OSCs, made with the blend layer of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] -[3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl

Electroless silver plating of the surface of organic semiconductors.

Science.gov (United States)

Campione, Marcello; Parravicini, Matteo; Moret, Massimo; Papagni, Antonio; Schröter, Bernd; Fritz, Torsten

2011-10-04

The integration of nanoscale processes and devices demands fabrication routes involving rapid, cost-effective steps, preferably carried out under ambient conditions. The realization of the metal/organic semiconductor interface is one of the most demanding steps of device fabrication, since it requires mechanical and/or thermal treatments which increment costs and are often harmful in respect to the active layer. Here, we provide a microscopic analysis of a room temperature, electroless process aimed at the deposition of a nanostructured metallic silver layer with controlled coverage atop the surface of single crystals and thin films of organic semiconductors. This process relies on the reaction of aqueous AgF solutions with the nonwettable crystalline surface of donor-type organic semiconductors. It is observed that the formation of a uniform layer of silver nanoparticles can be accomplished within 20 min contact time. The electrical characterization of two-terminal devices performed before and after the aforementioned treatment shows that the metal deposition process is associated with a redox reaction causing the p-doping of the semiconductor. © 2011 American Chemical Society

Rapid, sensitive, and selective fluorescent DNA detection using iron-based metal-organic framework nanorods: Synergies of the metal center and organic linker.

Science.gov (United States)

Tian, Jingqi; Liu, Qian; Shi, Jinle; Hu, Jianming; Asiri, Abdullah M; Sun, Xuping; He, Yuquan

2015-09-15

Considerable recent attention has been paid to homogeneous fluorescent DNA detection with the use of nanostructures as a universal "quencher", but it still remains a great challenge to develop such nanosensor with the benefits of low cost, high speed, sensitivity, and selectivity. In this work, we report the use of iron-based metal-organic framework nanorods as a high-efficient sensing platform for fluorescent DNA detection. It only takes about 4 min to complete the whole "mix-and-detect" process with a low detection limit of 10 pM and a strong discrimination of single point mutation. Control experiments reveal the remarkable sensing behavior is a consequence of the synergies of the metal center and organic linker. This work elucidates how composition control of nanostructures can significantly impact their sensing properties, enabling new opportunities for the rational design of functional materials for analytical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

A coverage and slicing dependencies analysis for seeking software security defects.

Science.gov (United States)

He, Hui; Zhang, Dongyan; Liu, Min; Zhang, Weizhe; Gao, Dongmin

2014-01-01

Software security defects have a serious impact on the software quality and reliability. It is a major hidden danger for the operation of a system that a software system has some security flaws. When the scale of the software increases, its vulnerability has becoming much more difficult to find out. Once these vulnerabilities are exploited, it may lead to great loss. In this situation, the concept of Software Assurance is carried out by some experts. And the automated fault localization technique is a part of the research of Software Assurance. Currently, automated fault localization method includes coverage based fault localization (CBFL) and program slicing. Both of the methods have their own location advantages and defects. In this paper, we have put forward a new method, named Reverse Data Dependence Analysis Model, which integrates the two methods by analyzing the program structure. On this basis, we finally proposed a new automated fault localization method. This method not only is automation lossless but also changes the basic location unit into single sentence, which makes the location effect more accurate. Through several experiments, we proved that our method is more effective. Furthermore, we analyzed the effectiveness among these existing methods and different faults.

Metal-organic frameworks at interfaces of hybrid perovskite solar cells for enhanced photovoltaic properties.

Science.gov (United States)

Shen, Deli; Pang, Aiying; Li, Yafeng; Dou, Jie; Wei, Mingdeng

2018-01-31

In this study, metal-organic frameworks, as an interfacial layer, were introduced into perovskite solar cells (PSCs) for the first time. An interface modified with the metal-organic framework ZIF-8 efficiently enhanced perovskite crystallinity and grain sizes, and the photovoltaic performance of the PSCs was significantly improved, resulting in a maximum PCE of 16.99%.

Investing in Nurses is a Prerequisite for Ensuring Universal Health Coverage.

Science.gov (United States)

Kurth, Ann E; Jacob, Sheena; Squires, Allison P; Sliney, Anne; Davis, Sheila; Stalls, Suzanne; Portillo, Carmen J

2016-01-01

Nurses and midwives constitute the majority of the global health workforce and the largest health care expenditure. Efficient production, successful deployment, and ongoing retention based on carefully constructed policies regarding the career opportunities of nurses, midwives, and other providers in health care systems are key to ensuring universal health coverage. Yet nurses are constrained by practice regulations, workplaces, and career ladder barriers from contributing to primary health care delivery. Evidence shows that quality HIV care, comparable to that of physicians, is provided by trained nurses and associate clinicians, but many African countries' health systems remain dependent on limited numbers of physicians and fail to meet the demand for treatment. The World Health Organization endorses task sharing to ensure universal health coverage in HIV and maternal health, which requires an investment in nursing education, retention, and professional growth opportunities. Exemplars from Haiti, Rwanda, Republic of Georgia, and multi-country efforts are described. Copyright © 2016 Association of Nurses in AIDS Care. Published by Elsevier Inc. All rights reserved.

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

Enhanced Emission by Accumulated Charges at Organic/Metal Interfaces Generated during the Reverse Bias of Organic Light Emitting Diodes

Directory of Open Access Journals (Sweden)

Soichiro Nozoe

2017-10-01

Full Text Available A high frequency rectangular alternating voltage was applied to organic light emitting diodes (OLEDs with the structure ITO/TPD/Alq3/Al and ITO/CoPc/Alq3/Al, where ITO is indium-tin-oxide, TPD is 4,4′-bis[N-phenyl-N-(m-tolylamino]biphenyl, CoPc is cobalt phthalocyanine, and Alq3 is Tris(8-quinolinolatoaluminum, and the effect on emission of the reverse bias was examined. The results reveal that the emission intensity under an alternating reverse-forward bias is greater than that under an alternating zero-forward bias. The difference in the emission intensity (∆I increased both for decreasing frequency and increasing voltage level of the reverse bias. In particular, the change in emission intensity was proportional to the voltage level of the reverse bias given the same frequency. To understand ΔI, this paper proposes a model in which an OLED works as a capacitor under reverse bias, where positive and negative charges accumulate on the metal/organic interfaces. In this model, the emission enhancement that occurs during the alternating reverse-forward bias is rationalized as a result of the charge accumulation at the organic/metal interfaces during the reverse bias, which possibly modulates the vacuum level shifts at the organic/metal interfaces to reduce both the hole injection barrier at the organic/ITO interface and the electron injection barrier at the organic/Al interface under forward bias.

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.

Dubinin-Astakhov model for acetylene adsorption on metal-organic frameworks

International Nuclear Information System (INIS)

Cheng, Peifu; Hu, Yun Hang

2016-01-01

Graphical abstract: It was demonstrated that Dubinin-Astakhov equation can be exploited as a general isotherm model for C2H2 adsorption on metal-organic frameworks (MOFs), including MOF-5, ZIF-8, HKUST-1, and MIL-53. - Highlights: • Dubinin-Astakhov equation is demonstrated to be a general model for C_2H_2 adsorption on metal-organic frameworks (MOFs). • Surface areas obtained with Dubinin-Astakhov equation from C_2H_2 adsorption on MOFs are consistent with BET surface areas from N_2 adsorption. • C_2H_2 on MOF-5, ZIF-8, and MIL-53 is a physical adsorption, whereas its adsorption on HKUST-1 is due to a chemical bonding. - Abstract: Acetylene (C_2H_2) is explosive at a pressure above 29 psi, causing a safety issue for its storage and applications. C_2H_2 adsorption on metal-organic frameworks (MOFs) has been explored to solve the issue. However, a suitable isotherm equation for C_2H_2 adsorption on various MOFs has not been found. In this paper, it was demonstrated that Dubinin-Astakhov equation can be exploited as a general isotherm model to depict C_2H_2 adsorption on MOF-5, ZIF-8, HKUST-1, and MIL-53. In contrast, commonly used Langmuir and BET models exhibited their inapplicability for C_2H_2 adsorption on those MOFs.

New metal-organic nanomaterials synthesized by laser irradiation of organic liquids

Energy Technology Data Exchange (ETDEWEB)

Kuzmin, Stanislav L.; Wesolowski, Michal J.; Duley, Walter W. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)

2014-03-31

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.

Volume fraction dependence of transient absorption signal and nonlinearities in metal nanocolloids

International Nuclear Information System (INIS)

Jayabalan, J; Singh, Asha; Khan, Salahuddin; Chari, Rama

2013-01-01

Electron–lattice thermalization dynamics in metal nanoparticles or in bulk metal is usually estimated by measuring the decay time of the change in transmission following an optical excitation. Such measurements can be performed in transient absorption geometry using a femtosecond laser. We find that for silver nanoplatelet/water colloids, the decay time of the transient absorption depends on the volume fraction of silver in water. By estimating the volume fraction dependence of nonlinearities in the same samples, we show that the variation in the measured decay time is due to pump-depletion effects present in the sample. The correct correction factor for taking into account pump-depletion effects in fifth- and higher-order nonlinearities is also presented. (paper)

Synthesis of organically-capped metallic zinc nanoparticles using electrical explosion of wires (EEW) coupled with PIERMEN

Energy Technology Data Exchange (ETDEWEB)

Abdelkader, Elseddik M.; Jelliss, Paul A., E-mail: jellissp@slu.edu; Buckner, Steven W., E-mail: buckners@slu.edu

2015-01-15

In this study zinc nanoparticles (ZNPs) were produced using electrical explosion of wires (EEW) with NP size around 100 nm. The explosion chamber was constructed from Teflon to withstand the shockwave, to allow growth and reaction of the incipient ZNPs in various organic solvents, and to allow a constant flow of argon creating an inert atmosphere. We utilized polymerization initiation by electron-rich metallic nanoparticles (PIERMEN) as the capping technique for the reactive ZNPs. Epoxides and alkenes served as the capping monomers. Epoxide caps underwent oligomerization on the surface of the NPs to form a protective polyether cap which renders the particles stable, non-pyrophoric in air, and dispersible in organic solvents. We investigated various Zn to monomer molar ratios varying from 1:1 to 10:1. Polyethylene glycol was also used as a capping agent and was found to give the smallest average Zn core sizes with the metal core diameters varying from 15 to 20 nm. Several solvents were used to study differences in resultant particle size and we observe toluene to give the smallest metal cores. Transmission electron microscopy shows the spherical particles with the metallic core embedded in a polymer matrix. The sample consists of predominantly smaller particles, but there was also a broad size distribution giving a range of 20–150 nm. Powder X-ray diffraction (PXRD) was used to confirm the identity of the metallic NPs. The capping agents were characterized using both attenuated total reflectance-Fourier transform infra-red (ATR-FTIR) and Raman spectroscopies. There was no evidence for formation of zinc oxide with appropriate organic capping agents and solvent combinations; thus, this is the first report of production of pure metallic zinc nanoparticles with an organic cap using EEW. - Highlights: • Organically-capped Zn metal nanoparticles are produced by EEW in organic solution. • Incipient Zn metal nanoparticles initiate oligomerization of epoxide and

SU-F-T-443: Quantification of Dosimetric Effects of Dental Metallic Implant On VMAT Plans

Energy Technology Data Exchange (ETDEWEB)

Lin, C; Jiang, W [East Carolina University, Greenville, NC (United States); Feng, Y [East Carolina University (United States); Huang, Z [East Carolina University, Greenville, North Carolina (United States)

2016-06-15

Purpose: To evaluate the dosimetric impact of metallic implant that correlates with the size of targets and metallic implants and distance in between on volumetric-modulated arc therapy (VMAT) plans for head and neck (H&N) cancer patients with dental metallic implant. Methods: CT images of H&N cancer patients with dental metallic implant were used. Target volumes with different sizes and locations were contoured. Metal artifact regions excluding surrounding critical organs were outlined and assigned with CT numbers close to water (0HU). VMAT plans with half-arc, one-full-arc and two-full-arcs were constructed and same plans were applied to structure sets with and without CT number assignment of metal artifact regions and compared. D95% was utilized to investigate PTV dose coverage and SNC Patient− Software was used for the analysis of dose distribution difference slice by slice. Results: For different targets sizes, variation of PTV dose coverage (Delta-D95%) with and without CT number replacement reduced with larger target volume for all half-arc, one-arc and two-arc VMAT plans even though there were no clinically significant differences. Additionally, there were no significant variations of the maximum percent difference (max.%diff) of dose distribution. With regard to the target location, Delta-D95% and max. %diff dropped with increasing distance between target and metallic implant. Furthermore, half-arc plans showed greater impact than one-arc plans, and two-arc plans had smallest influence for PTV dose coverage and dose distribution. Conclusion: The target size has less correlation of doseimetric impact than the target location relative to metallic implants. Plans with more arcs alleviate the dosimetric effect of metal artifact because of less contribution to the target dose from beams going through the regions with metallic artifacts. Incorrect CT number causes inaccurate dose distribution, therefore appropriately overwriting metallic artifact regions with

SU-F-T-443: Quantification of Dosimetric Effects of Dental Metallic Implant On VMAT Plans

International Nuclear Information System (INIS)

Lin, C; Jiang, W; Feng, Y; Huang, Z

2016-01-01

Purpose: To evaluate the dosimetric impact of metallic implant that correlates with the size of targets and metallic implants and distance in between on volumetric-modulated arc therapy (VMAT) plans for head and neck (H&N) cancer patients with dental metallic implant. Methods: CT images of H&N cancer patients with dental metallic implant were used. Target volumes with different sizes and locations were contoured. Metal artifact regions excluding surrounding critical organs were outlined and assigned with CT numbers close to water (0HU). VMAT plans with half-arc, one-full-arc and two-full-arcs were constructed and same plans were applied to structure sets with and without CT number assignment of metal artifact regions and compared. D95% was utilized to investigate PTV dose coverage and SNC Patient− Software was used for the analysis of dose distribution difference slice by slice. Results: For different targets sizes, variation of PTV dose coverage (Delta_D95%) with and without CT number replacement reduced with larger target volume for all half-arc, one-arc and two-arc VMAT plans even though there were no clinically significant differences. Additionally, there were no significant variations of the maximum percent difference (max.%diff) of dose distribution. With regard to the target location, Delta_D95% and max. %diff dropped with increasing distance between target and metallic implant. Furthermore, half-arc plans showed greater impact than one-arc plans, and two-arc plans had smallest influence for PTV dose coverage and dose distribution. Conclusion: The target size has less correlation of doseimetric impact than the target location relative to metallic implants. Plans with more arcs alleviate the dosimetric effect of metal artifact because of less contribution to the target dose from beams going through the regions with metallic artifacts. Incorrect CT number causes inaccurate dose distribution, therefore appropriately overwriting metallic artifact regions with

A model for temperature dependent resistivity of metallic superlattices

Directory of Open Access Journals (Sweden)

J. I. Uba

2015-11-01

Full Text Available The temperature dependent resistivity of metallic superlattices, to first order approximation, is assumed to have same form as bulk metal, ρ(T = ρo + aT, which permits describing these structures as linear atomic chain. The assumption is, substantiated with the derivation of the above expression from the standard magnetoresistance equation, in which the second term, a Bragg scattering factor, is a correction to the usual model involving magnon and phonon scatterings. Fitting the model to Fe/Cr data from literature shows that Bragg scattering is dominant at T < 50 K and magnon and phonon coefficients are independent of experiment conditions, with typical values of 4.7 × 10−4 μΩcmK−2 and −8 ± 0.7 × 10−7μΩcmK−3. From the linear atomic chain model, the dielectric constant ε q , ω = 8 . 33 × 10 − 2 at Debye frequency for all materials and acoustic speed and Thomas – Fermi screening length are pressure dependent with typical values of 1.53 × 104 m/s and 1.80 × 109 m at 0.5 GPa pressure for an Fe/Cr structure.

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.

Fully solution-processed organic solar cells on metal foil substrates

KAUST Repository

Gaynor, Whitney; Lee, Jung-Yong; Peumans, Peter

2009-01-01

We demonstrate fully solution-processed organic photovoltaic cells on metal foil substrates with power conversion efficiencies similar to those obtained in devices on transparent substrates. The cells are based on the regioregular poly- (3

Relating environmental availability to bioavailability: soil-type-dependent metal accumulation in the oligochaete Eisenia andrei.

Science.gov (United States)

Peijnenburg, W J; Baerselman, R; de Groot, A C; Jager, T; Posthuma, L; Van Veen, R P

1999-11-01

Body residues are often better estimates of the amount of a chemical at the sites of toxic action in an organism than ambient soil concentrations, because bioavailability differences among soils are explicitly taken into account in considerations of body residues. Often, however, insufficient attention is paid to the rate and extent at which tissue concentrations respond to soil concentrations and soil characteristics. In this contribution the impact of soil characteristics on the environmental bioavailability of heavy metals for the oligochaete worm Eisenia andrei is reported. Uptake of As, Cd, Cr, Cu, Ni, Pb, and Zn in 20 Dutch field soils and in OECD artificial soil was quantified as a function of time. Internal metal concentrations varied less than the corresponding external levels. Metal uptake and elimination were both metal- and species-dependent. Worms typically attained steady-state concentrations rapidly for Cr, Cu, Ni, and Zn. Internal concentrations similar to those in the cultivation medium, linearly increasing body concentrations, or steady-state internal concentrations well above those in the cultivation medium were found for As, Cd, and Pb. Multivariate expressions were derived to describe uptake rate constants, steady-state concentrations, and bioaccumulation factors as a function of soil characteristics. Soil acidity is the most important solid-phase characteristic modulating the availability of As, Cd, and Pb. Although additional semimechanistic calculations yielded evidence of pore-water-related uptake of Cd and Pb modulated by competition between H(+) and metal ions at the active sites of the membranes, the findings for Cr, Cu, Ni, and Zn point to additional influences, among which is probably regulation. Copyright 1999 Academic Press.

Metal-doped organic foam and method of making same. [Patent application

Science.gov (United States)

Rinde, J.A.

Organic foams having a low density and very small cell size and method for producing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

A simple method to prepare self-assembled organic-organic heterobilayers on metal substrates

Directory of Open Access Journals (Sweden)

L. D. Sun

2011-06-01

Full Text Available We demonstrate a self-assembly based simple method to prepare organic-organic heterobilayers on a metal substrate. By either sequential- or co-deposition of para-sexiphenyl (p-6P and pentacene molecules onto the Cu(110 surface in ultrahigh vacuum, p-6P/pentacene/Cu(110 heterobilayer is synthesized at room temperature. The layer sequence of the heterostructure is independent of the growth scenario indicating the p-6P/pentacene/Cu(110 is a self-assembled structure with lowest energy. Besides, the bilayer shows a very high orientational ordering and is thermally stable up to 430K.

Volume dependence of the melting temperature for alkali metals with Debye's model

International Nuclear Information System (INIS)

Soma, T.; Kagaya, H.M.; Nishigaki, M.

1983-01-01

Using the volume dependence of the Grueneisen constant at higher temperatures, the volume effect on the melting temperature of alkali metals is studied by Lindeman's melting law and Debye's model. The obtained melting curve increases as a function of the compressed volume and shows the maximum of the melting point at the characteristic volume. The resultant data are qualitatively in agreement with the observed tendency for alkali metals. (author)

Classification of Plants According to Their Heavy Metal Content ...

African Journals Online (AJOL)

Plants like other living organisms respond differently under different environmental conditions. An elevated level of heavy metals is one of the stresses which results into three classes of plants depending on their heavy metal content. The classes of plant species according to their accumulated heavy metals around North ...

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Science.gov (United States)

2010-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 62.14103 Section 62.14103 Protection of... combustor metals, acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals are specified in paragraphs (a)(1) through (a)(3) of this section. (1) The owner or...

CFA-7: an interpenetrated metal-organic framework of the MFU-4 family.

Science.gov (United States)

Schmieder, Phillip; Grzywa, Maciej; Denysenko, Dmytro; Hambach, Manuel; Volkmer, Dirk

2015-08-07

The novel interpenetrated metal-organic framework CFA-7 (Coordination Framework Augsburg University-7), [Zn5Cl4(tqpt)3], has been synthesized containing the organic linker {H2-tqpt = 6,6,14,14-tetramethyl-6,14-dihydroquinoxalino[2,3-b]phenazinebistriazole}. Reaction of H2-tqpt and anhydrous ZnCl2 in N,N-dimethylformamide (DMF) yields CFA-7 as pseudo-cubic crystals. CFA-7 serves as precursor for the synthesis of isostructural frameworks with redox-active metal centers, which is demonstrated by postsynthetic metal exchange of Zn(2+) by different M(2+) (M = Co, Ni, Cu) ions. The novel framework is robust upon solvent removal and has been structurally characterized by single-crystal X-ray diffraction, TGA and IR spectroscopy, as well as gas sorption (Ar, CO2 and H2).

Boundary-integral equation formulation for time-dependent inelastic deformation in metals

Energy Technology Data Exchange (ETDEWEB)

Kumar, V; Mukherjee, S

1977-01-01

The mathematical structure of various constitutive relations proposed in recent years for representing time-dependent inelastic deformation behavior of metals at elevated temperatues has certain features which permit a simple formulation of the three-dimensional inelasticity problem in terms of real time rates. A direct formulation of the boundary-integral equation method in terms of rates is discussed for the analysis of time-dependent inelastic deformation of arbitrarily shaped three-dimensional metallic bodies subjected to arbitrary mechanical and thermal loading histories and obeying constitutive relations of the kind mentioned above. The formulation is based on the assumption of infinitesimal deformations. Several illustrative examples involving creep of thick-walled spheres, long thick-walled cylinders, and rotating discs are discussed. The implementation of the method appears to be far easier than analogous BIE formulations that have been suggested for elastoplastic problems.

Synthesis of Pd and Rh metal nanoparticles in the interlayer space of organically modified montmorillonite

International Nuclear Information System (INIS)

Patel, Hasmukh A.; Bajaj, Hari C.; Jasra, Raksh Vir

2008-01-01

This study reports the synthesis of palladium and rhodium metal nanoparticles supported on montmorillonite (MMT) and partially organically modified MMT (POMM) using tetraamine palladium and hexaamine rhodium complex as precursor for palladium and rhodium respectively. The synthesized nanoparticles were characterized by powder X-ray diffraction PXRD and TEM. The PXRD study shows characteristic crystallographic planes for Pd and Rh metal and confirm the formation of metal nanoparticles in MMT and POMM. The TEM images reveal the effect of organic modification of MMT on decreasing particle size of Pd and Rh metal. The Pd and Rh metal nanoparticles are agglomerated in pristine MMT while nanoparticles are well dispersed in POMM. ICP-AES analysis was carried out to estimate quantitative amount of Pd and Rh metal in MMT and POMM

Linear and nonlinear surface spectroscopy of supported size selected metal clusters and organic adsorbates

Energy Technology Data Exchange (ETDEWEB)

Thaemer, Martin Georg

2012-03-08

The spectroscopic investigation of supported size selected metal clusters over a wide wavelength range plays an important role for understanding their outstanding catalytic properties. The challenge which must be overcome to perform such measurements is the difficult detection of the weak spectroscopic signals from these samples. As a consequence, highly sensitive spectroscopic methods are applied, such as surface Cavity Ringdown Spectroscopy and surface Second Harmonic Generation Spectroscopy. The spectroscopic apparatus developed is shown to have a sensitivity which is high enough to detect sub-monolayer coverages of adsorbates on surfaces. In the measured spectra of small supported silver clusters of the sizes Ag{sub 4}2, Ag{sub 2}1, Ag{sub 9}, and Ag atoms a stepwise transition from particles with purely metallic character to particles with molecule-like properties can be observed within this size range.

Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

Energy Technology Data Exchange (ETDEWEB)

Zhao, Jian, E-mail: zhaojian0209@aliyun.com [Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); He, Man-Chao [State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China)

2014-10-30

Highlights: • We investigated the adsorption of Cd, Cu, Hg, and Ni(II) on kaolinite(0 0 1) surface. • The adsorption capabilities of the kaolinite for HM atoms were Ni > Cu > Cd > Hg(II). • The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms. • The adsorption energy decreases with the coverage for Ni(II) atoms. - Abstract: Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail.

Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

International Nuclear Information System (INIS)

Zhao, Jian; He, Man-Chao

2014-01-01

Highlights: • We investigated the adsorption of Cd, Cu, Hg, and Ni(II) on kaolinite(0 0 1) surface. • The adsorption capabilities of the kaolinite for HM atoms were Ni > Cu > Cd > Hg(II). • The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms. • The adsorption energy decreases with the coverage for Ni(II) atoms. - Abstract: Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail

Metal-organic frameworks with dynamic interlocked components

Science.gov (United States)

Vukotic, V. Nicholas; Harris, Kristopher J.; Zhu, Kelong; Schurko, Robert W.; Loeb, Stephen J.

2012-06-01

The dynamics of mechanically interlocked molecules such as rotaxanes and catenanes have been studied in solution as examples of rudimentary molecular switches and machines, but in this medium, the molecules are randomly dispersed and their motion incoherent. As a strategy for achieving a higher level of molecular organization, we have constructed a metal-organic framework material using a [2]rotaxane as the organic linker and binuclear Cu(II) units as the nodes. Activation of the as-synthesized material creates a void space inside the rigid framework that allows the soft macrocyclic ring of the [2]rotaxane to rotate rapidly, unimpeded by neighbouring molecular components. Variable-temperature 13C and 2H solid-state NMR experiments are used to characterize the nature and rate of the dynamic processes occurring inside this unique material. These results provide a blueprint for the future creation of solid-state molecular switches and molecular machines based on mechanically interlocked molecules.

NOAA Weather Radio - County Coverage by State

Science.gov (United States)

Non-Zero All Hazards Logo Emergency Alert Description Event Codes Fact Sheet FAQ Organization Search Coverage Listings NWR Station Search Maps SAME SAME Coding Using SAME SAME Non-Zero Codes DOCUMENTS NWR

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.

ON A NEW THEORETICAL FRAMEWORK FOR RR LYRAE STARS. I. THE METALLICITY DEPENDENCE

International Nuclear Information System (INIS)

Marconi, M.; Coppola, G.; Musella, I.; Ripepi, V.; Bono, G.; Braga, V.; Buonanno, R.; Pietrinferni, A.; Castellani, M.; Stellingwerf, R. F.

2015-01-01

We present new nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio and a broad range in metal abundances (Z = 0.0001–0.02). The stellar masses and luminosities adopted to construct the pulsation models were fixed according to detailed central He-burning horizontal-branch evolutionary models. The pulsation models cover a broad range in stellar luminosity and effective temperatures and the modal stability is investigated for both fundamental (FU) and first overtone polsators (FOs). We predict the topology of the instability strip (IS) as a function of the metal content and new analytical relations for the edges of the IS in the observational plane. Moreover, a new analytical relation to constrain the pulsation mass of double pulsators as a function of the period ratio and the metal content is provided. We derive new Period–Radius–Metallicity relations for FU and FO pulsators. They agree quite well with similar empirical and theoretical relations in the literature. From the predicted bolometric light curves, transformed into optical (UBVRI) and near-infrared (NIR; JHK) bands, we compute the intensity-averaged mean magnitudes along the entire pulsation cycle and in turn new and homogenous metal-dependent (RIJHK) Period–Luminosity relations. Moreover, we compute new dual and triple-band optical, optical–NIR, and NIR Period–Wesenheit–Metallicity relations. Interestingly, we find that the optical Period-W(V, B–V) is independent of the metal content and that the accuracy of individual distances is a balance between the adopted diagnostics and the precision of photometric and spectroscopic data sets

Adsorptive removal of naproxen and clofibric acid from water using metal-organic frameworks.

Science.gov (United States)

Hasan, Zubair; Jeon, Jaewoo; Jhung, Sung Hwa

2012-03-30

Adsorptive removal of naproxen and clofibric acid, two typical PPCPs (pharmaceuticals and personal care products), has been studied using metal-organic frameworks (MOFs) for the first time. The removal efficiency decreases in the order of MIL-101>MIL-100-Fe>activated carbon both in adsorption rate and adsorption capacity. The adsorption kinetics and capacity of PPCPs generally depend on the average pore size and surface area (or pore volume), respectively, of the adsorbents. The adsorption mechanism may be explained with a simple electrostatic interaction between PPCPs and the adsorbent. Finally, it can be suggested that MOFs having high porosity and large pore size can be potential adsorbents to remove harmful PPCPs in contaminated water. Copyright © 2012 Elsevier B.V. All rights reserved.

Study of the trace metal ion influence on the turnover of soil organic matter in cultivated contaminated soils

International Nuclear Information System (INIS)

Dumat, C.; Quenea, K.; Bermond, A.; Toinen, S.; Benedetti, M.F.

2006-01-01

The role of metals in the behaviour of soil organic matter (SOM) is not well documented. Therefore, we investigated the influence of metals (Pb, Zn, Cu and Cd) on the dynamic of SOM in contaminated soils where maize (C 4 plant) replaced C 3 cultures. Three pseudogley brown leached soil profiles under maize with a decreasing gradient in metals concentrations were sampled. On size fractions, stable carbon isotopic ratio (δ 13 C), metals, organic carbon and nitrogen concentrations were measured in function of depth. The determined sequence for the amount of C 4 organic matter in the bulk fractions: M 3 (0.9) > M 2 (0.4) > M 1 (0.3) is in agreement with a significant influence of metals on the SOM turnover. New C 4 SOM, mainly present in the labile coarser fractions and less contaminated by metals than the stabilised C 3 SOM of the clay fraction, is more easily degraded by microorganisms. - Measure of δ 13 C and total metal concentrations in size fractions of contaminated soils suggests an influence of metals on the soil organic matter dynamic

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.

SDSS-IV MaNGA: environmental dependence of stellar age and metallicity gradients in nearby galaxies

Science.gov (United States)

Zheng, Zheng; Wang, Huiyuan; Ge, Junqiang; Mao, Shude; Li, Cheng; Li, Ran; Mo, Houjun; Goddard, Daniel; Bundy, Kevin; Li, Hongyu; Nair, Preethi; Lin, Lihwai; Long, R. J.; Riffel, Rogério; Thomas, Daniel; Masters, Karen; Bizyaev, Dmitry; Brownstein, Joel R.; Zhang, Kai; Law, David R.; Drory, Niv; Roman Lopes, Alexandre; Malanushenko, Olena

2017-03-01

We present a study on the stellar age and metallicity distributions for 1105 galaxies using the STARLIGHT software on MaNGA (Mapping Nearby Galaxies at APO) integral field spectra. We derive age and metallicity gradients by fitting straight lines to the radial profiles, and explore their correlations with total stellar mass M*, NUV - r colour and environments, as identified by both the large-scale structure (LSS) type and the local density. We find that the mean age and metallicity gradients are close to zero but slightly negative, which is consistent with the inside-out formation scenario. Within our sample, we find that both the age and metallicity gradients show weak or no correlation with either the LSS type or local density environment. In addition, we also study the environmental dependence of age and metallicity values at the effective radii. The age and metallicity values are highly correlated with M* and NUV - r and are also dependent on LSS type as well as local density. Low-mass galaxies tend to be younger and have lower metallicity in low-density environments while high-mass galaxies are less affected by environment.

Correlation between organic acid exudation and metal uptake by ectomycorrhizal fungi grown on pond ash in vitro

Energy Technology Data Exchange (ETDEWEB)

Ray, P.; Adholeya, A. [Energy & Resources Institute, New Delhi (India). India Habitat Centre

2009-04-15

Experiments were conducted to investigate the effect of coal ash on organic acid exudation and subsequent metal uptake by ectomycorrhizal fungi. Four isolates of ectomycorrhizal fungi namely, Pisolithus tinctorius (EM-1293 and EM-1299), Scleroderma verucosum (EM-1283) and Scleroderma cepa (EM-1233) were grown on pond ash moistened with Modified Melin-Norkans medium in vitro. Exudation of formic acid, malic acid and succinic acid by these fungi were detected by HPLC. Mycelial accumulation of Al, As, Cd, Cr, Ni and Pb by these fungi was assayed by atomic absorption spectrophotometer. Relationship between organic acid exudation and metal uptake was determined using classical multivariate linear regression model. Correlation between organic acid exudation and metal uptake could be substantiated when several metals are considered collectively. The finding supports the widespread role of low molecular weight organic acid as a function of tolerance, when exposed to metals in vitro.

Amino-functionalized metal-organic frameworks as tunable heterogeneous basic catalysts

Energy Technology Data Exchange (ETDEWEB)

Fischer, M.; Hartmann, M. [Erlangen-Nuernberg Univ., Erlangen (Germany). Erlangen Catalysis Resource Center

2011-07-01

Metal-organic framework (MOF) materials have been explored for applications in heterogeneous catalysis in recent years. In addition to the use of MOFs as supports for the deposition of highly dispersed metal particles, the incorporation of active centers such as coordinatively unsaturated metal sites and the functionalization of the organic linkers with acidic or basic groups seems to be most promising. In our contribution, three different MOFs carrying amino groups at their organic linkers, namely Fe-MIL-101-NH{sub 2} (S{sub BET} = 3438 m{sup 2}g{sup -1}), Al-MIL-101-NH{sub 2} (S{sub BET} = 3099 m{sup 2}g{sup -1}) and CAU-1 (S{sub BET} = 1492 m{sup 2}g{sup -1}), were synthesized and tested in the Knoevenagel condensation of benzaldehyde with malononitrile and with ethyl cyanoacetate, respectively. It is shown that the expected products benzylidenemalononitrile (BzMN) and ethyl a-cyanocinnamate (EtCC) are formed with selectivities of more than 99 % and yields of 90 to 95 % after 3 h (for BzMN). Due to the very small pore windows of CAU-1 (0.3 to 0.4 nm) the reaction proceeds much slower over this catalyst in comparison to the amino-MIL-101 derivatives, which possess open pore windows of up to 1.6 nm. Finally, leaching tests confirm that the reaction is heterogeneously catalyzed. Moreover, the catalysts are recyclable without significant loss of activity. (orig.)

Dubinin-Astakhov model for acetylene adsorption on metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Cheng, Peifu; Hu, Yun Hang, E-mail: yunhangh@mtu.edu

2016-07-30

Graphical abstract: It was demonstrated that Dubinin-Astakhov equation can be exploited as a general isotherm model for C2H2 adsorption on metal-organic frameworks (MOFs), including MOF-5, ZIF-8, HKUST-1, and MIL-53. - Highlights: • Dubinin-Astakhov equation is demonstrated to be a general model for C{sub 2}H{sub 2} adsorption on metal-organic frameworks (MOFs). • Surface areas obtained with Dubinin-Astakhov equation from C{sub 2}H{sub 2} adsorption on MOFs are consistent with BET surface areas from N{sub 2} adsorption. • C{sub 2}H{sub 2} on MOF-5, ZIF-8, and MIL-53 is a physical adsorption, whereas its adsorption on HKUST-1 is due to a chemical bonding. - Abstract: Acetylene (C{sub 2}H{sub 2}) is explosive at a pressure above 29 psi, causing a safety issue for its storage and applications. C{sub 2}H{sub 2} adsorption on metal-organic frameworks (MOFs) has been explored to solve the issue. However, a suitable isotherm equation for C{sub 2}H{sub 2} adsorption on various MOFs has not been found. In this paper, it was demonstrated that Dubinin-Astakhov equation can be exploited as a general isotherm model to depict C{sub 2}H{sub 2} adsorption on MOF-5, ZIF-8, HKUST-1, and MIL-53. In contrast, commonly used Langmuir and BET models exhibited their inapplicability for C{sub 2}H{sub 2} adsorption on those MOFs.

Trace Metals And Organic Matter Diagenesis At The Oman Margin

Digital Repository Service at National Institute of Oceanography (India)

Alagarsamy, R.

Trace Metals (e.g. Mn and Fe) play an important role as secondary oxidants in the degradation of sedimentary OM under sub-oxic conditions. Hence the remineralisation of organic constituents of sediments in the marine environment may significantly...

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.

Dual-affinity peptides to generate dense surface coverages of nanoparticles

International Nuclear Information System (INIS)

Del Re, Julia; Blum, Amy Szuchmacher

2014-01-01

Graphical abstract: - Highlights: • Stable nanoparticles were created with the Flg-A3 fusion peptide as a ligand. • Interactions of transition metal ions with Flg control aggregation of the nanoparticles in solution. • The QBP1-A3 fusion peptide improves surface attachment of gold nanoparticles. • Solution pre-aggregation of nanoparticles results in dense surface coverage. - Abstract: Depositing gold nanoparticles is of great interest because of the many potential applications of nanoparticle films; however, generating dense surface nanoparticle coverage remains a difficult challenge. Using dual-affinity peptides we have synthesized gold nanoparticles and then pre-aggregated the particles in solution via interactions with metal ions. These nanoparticle aggregates were then deposited onto silicon dioxide surfaces using another dual-affinity peptide to control binding to the substrate. The results demonstrate that when divalent ions like Zn 2+ or Ni 2+ are used, densely packed gold nanoparticle monolayers are formed on the silicon dioxide substrate, which may have applications in fields like molecular electronics

Breaking Down Chemical Weapons by Metal-Organic Frameworks.

Science.gov (United States)

Mondal, Suvendu Sekhar; Holdt, Hans-Jürgen

2016-01-04

Seek and destroy: Filtration schemes and self-detoxifying protective fabrics based on the Zr(IV)-containing metal-organic frameworks (MOFs) MOF-808 and UiO-66 doped with LiOtBu have been developed that capture and hydrolytically detoxify simulants of nerve agents and mustard gas. Both MOFs function as highly catalytic elements in these applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoluminescence emission from Alq3 organic layer in metal–Alq3–metal plasmonic structure

Energy Technology Data Exchange (ETDEWEB)

Huang, Bohr-Ran; Liao, Chung-Chi [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Fan, Wan-Ting [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China); Wu, Jin-Han; Chen, Cheng-Chang; Lin, Yi-Ping; Li, Jung-Yu; Chen, Shih-Pu [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute (ITRI), 195, Sec. 4, Chung-Hsin Road, Chutung 310, Taiwan (China); Ke, Wen-Cheng [Department of Mechanical Engineering, Yuan Ze University, Tao-Yuan 320, Taiwan (China); Chen, Nai-Chuan, E-mail: ncchen001@mail.cgu.edu.tw [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

2014-06-01

The emission properties of an organic layer embedded in a metal–organic–metal (MOM) structure were investigated. A partially radiative odd-SPW as well as a non-radiative even-SPW modes are supported by hybridization of the SPW modes on the opposite organic/metal interface in the structure. Because of the competition by this radiative SPW, the population of excitons that recombine to form non-radiative SPW should be reduced. This may account for why the photoluminescence intensity of the MOM sample is higher than that of an organic–metal sample even though the MOM sample has an additional metal layer that should intuitively act as a filter.

Ultrastructural observations of target-organs of the crayfish Orconectes limosus exposed to metallic pollutants: application to uranium

International Nuclear Information System (INIS)

Grasset, G.; Simon, O.; Floriani, M.

2004-01-01

Using electron microscopy associated with energy dispersive X-ray microanalysis (EDAXTEM), ultrastructure and elemental analysis in subcellular micro-localization can bring understanding to both metabolic cycle of a metallic pollutant and its potential effects at the subcellular scale. The approach consists in comparing both structures and micro-localization in various tissues/organs ultrathin sections (70-140 nm thickness) obtained from control organisms (i.e. not exposed to a given metal) and exposed organisms. However, the observations of ultrastructural effects of metal exposure involved robust comparison to reference subcellular and cellular organization. Consequently, preliminary developments presented in this poster have been performed from the non-contaminated freshwater crayfish Orconectes limosus (adult at inter-moult state). Studies of ultrastructural images and elemental composition of subcellular mineral deposits were carried out on target organs of uranium accumulation such as the digestive gland, the gills, the intestine and the antennal gland, organs participating in the detoxification, primary accumulation and depuration mechanisms. Observations indicated cell-specific architecture (identification of main organelles, frequency, length of cells), the range of natural variation of the cell organisation between individuals and identification of cellular types. Information will allow then to focus on these identified specific organization after metallic exposure. These ultrastructural observations performed on reference organisms constitute necessarily a first set of data for the cellular metallic effects analysis. (author)

Pulse gas chromatographic study of adsorption of substituted aromatics and heterocyclic molecules on MIL-47 at zero coverage.

Science.gov (United States)

Duerinck, Tim; Couck, Sarah; Vermoortele, Frederik; De Vos, Dirk E; Baron, Gino V; Denayer, Joeri F M

2012-10-02

The low coverage adsorptive properties of the MIL-47 metal organic framework toward aromatic and heterocyclic molecules are reported in this paper. The effect of molecular functionality and size on Henry adsorption constants and adsorption enthalpies of alkyl and heteroatom functionalized benzene derivates and heterocyclic molecules was studied using pulse gas chromatography. By means of statistical analysis, experimental data was analyzed and modeled using principal component analysis and partial least-squares regression. Structure-property relationships were established, revealing and confirming several trends. Among the molecular properties governing the adsorption process, vapor pressure, mean polarizability, and dipole moment play a determining role.

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

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.

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

KAUST Repository

Eddaoudi, Mohamed; Adil, Karim; Belmabkhout, Youssef; Cadiau, Amandine

2016-01-01

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/H2

Accumulation of trace metals in coastal marine organisms

International Nuclear Information System (INIS)

Weers, A.W. van; Raaphorst, J.G. van

1980-01-01

ECN at Petten carries out a survey on the occurrence of trace metals in coastal marine organisms. The survey is aimed to provide an estimate of concentration factors in local marine organisms for neutron activation products released as low-level liquid radioactive waste into the North Sea. The organisms studied are red and brown seaweed, edible mussels ans shrimp. A summary of the results of analyses of iron, cobalt, zinc, silver and antimony in these organisms is presented. Concentration factors derived from mean stable-element concentrations range from about 50 for Sb in red seaweed and shrimp to about 10 4 for Fe in red seaweed and mussels. The largest variation is shown for zinc in seaweed, which variation is seasonal and most pronounced in brown seaweed. A discussion of the data is presented in relation to data from other West-European coastal areas and to data used for the radiological assessment of deep sea disposal of radioactive waste

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.

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...

Lymphoid Aggregates That Resemble Tertiary Lymphoid Organs Define a Specific Pathological Subset in Metal-on-Metal Hip Replacements

Science.gov (United States)

Barone, Francesca; Hardie, Debbie L.; Matharu, Gulraj S.; Davenport, Alison J.; Martin, Richard A.; Grant, Melissa; Mosselmans, Frederick; Pynsent, Paul; Sumathi, Vaiyapuri P.; Addison, Owen; Revell, Peter A.; Buckley, Christopher D.

2013-01-01

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) has been used to describe the histological lesion associated with metal-on-metal (M-M) bearings. We tested the hypothesis that the lymphoid aggregates, associated with ALVAL lesions resemble tertiary lymphoid organs (TLOs). Histopathological changes were examined in the periprosthetic tissue of 62 M-M hip replacements requiring revision surgery, with particular emphasis on the characteristics and pattern of the lymphocytic infiltrate. Immunofluorescence and immunohistochemistry were used to study the classical features of TLOs in cases where large organized lymphoid follicles were present. Synchrotron X-ray fluorescence (XRF) measurements were undertaken to detect localisation of implant derived ions/particles within the samples. Based on type of lymphocytic infiltrates, three different categories were recognised; diffuse aggregates (51%), T cell aggregates (20%), and organised lymphoid aggregates (29%). Further investigation of tissues with organised lymphoid aggregates showed that these tissues recapitulate many of the features of TLOs with T cells and B cells organised into discrete areas, the presence of follicular dendritic cells, acquisition of high endothelial venule like phenotype by blood vessels, expression of lymphoid chemokines and the presence of plasma cells. Co-localisation of implant-derived metals with lymphoid aggregates was observed. These findings suggest that in addition to the well described general foreign body reaction mediated by macrophages and a T cell mediated type IV hypersensitivity response, an under-recognized immunological reaction to metal wear debris involving B cells and the formation of tertiary lymphoid organs occurs in a distinct subset of patients with M-M implants. PMID:23723985

Metal-like self-organization of periodic nanostructures on silicon and silicon carbide under femtosecond laser pulses

International Nuclear Information System (INIS)

Gemini, Laura; Hashida, Masaki; Shimizu, Masahiro; Miyasaka, Yasuhiro; Inoue, Shunsuke; Tokita, Shigeki; Sakabe, Shuji; Limpouch, Jiri; Mocek, Tomas

2013-01-01

Periodic structures were generated on Si and SiC surfaces by irradiation with femtosecond laser pulses. Self-organized structures with spatial periodicity of approximately 600 nm appear on silicon and silicon carbide in the laser fluence range just above the ablation threshold and upon irradiation with a large number of pulses. As in the case of metals, the dependence of the spatial periodicity on laser fluence can be explained by the parametric decay of laser light into surface plasma waves. The results show that the proposed model might be universally applicable to any solid state material

Light-enhanced acid catalysis over a metal-organic framework.

Science.gov (United States)

Xu, Caiyun; Sun, Keju; Zhou, Yu-Xiao; Ma, Xiao; Jiang, Hai-Long

2018-03-06

A Brønsted acid-functionalized metal-organic framework (MOF), MIL-101-SO 3 H, was prepared for acid-engaged esterification reactions. Strikingly, for the first time, the MOF exhibits significantly light-enhanced activity and possesses excellent activity and recyclability, with even higher activity than H 2 SO 4 under light irradiation.

Hybrid Glasses from Strong and Fragile Metal-Organic Framework Liquids

DEFF Research Database (Denmark)

Bennett, T.D.; Tan, J.C.; Yue, Yuanzheng

2015-01-01

Hybrid glasses connect the emerging field of metal-organic frameworks (MOFs) with the glass formation, amorphization and melting processes of these chemically versatile systems. Though inorganic zeolites collapse around the glass transition and melt at higher temperatures, the relationship betwee...

Separation of polar compounds using a flexible metal-organic framework

NARCIS (Netherlands)

Motkuri, R.K.; Thallapally, P.K.; Annapureddy, H.V.R.; Dang, L.X.; Krishna, R.; Nune, S.K.; Fernandez, C.A.; Liu, J.; McGrail, B.P.

2015-01-01

A flexible metal-organic framework constructed from a flexible linker is shown to possess the capability of separating mixtures of polar compounds (propanol isomers) by exploiting the differences in the saturation capacities of the constituents. Transient breakthrough simulations show that these

A spin transition mechanism for cooperative adsorption in metal-organic frameworks

Science.gov (United States)

Reed, Douglas A.; Keitz, Benjamin K.; Oktawiec, Julia; Mason, Jarad A.; Runčevski, Tomče; Xiao, Dianne J.; Darago, Lucy E.; Crocellà, Valentina; Bordiga, Silvia; Long, Jeffrey R.

2017-10-01

Cooperative binding, whereby an initial binding event facilitates the uptake of additional substrate molecules, is common in biological systems such as haemoglobin. It was recently shown that porous solids that exhibit cooperative binding have substantial energetic benefits over traditional adsorbents, but few guidelines currently exist for the design of such materials. In principle, metal-organic frameworks that contain coordinatively unsaturated metal centres could act as both selective and cooperative adsorbents if guest binding at one site were to trigger an electronic transformation that subsequently altered the binding properties at neighbouring metal sites. Here we illustrate this concept through the selective adsorption of carbon monoxide (CO) in a series of metal-organic frameworks featuring coordinatively unsaturated iron(II) sites. Functioning via a mechanism by which neighbouring iron(II) sites undergo a spin-state transition above a threshold CO pressure, these materials exhibit large CO separation capacities with only small changes in temperature. The very low regeneration energies that result may enable more efficient Fischer-Tropsch conversions and extraction of CO from industrial waste feeds, which currently underutilize this versatile carbon synthon. The electronic basis for the cooperative adsorption demonstrated here could provide a general strategy for designing efficient and selective adsorbents suitable for various separations.

Heavy metals in benthic organisms from Todos os Santos Bay, Brazil

Directory of Open Access Journals (Sweden)

GM. Amado-Filho

Full Text Available The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. Despite its ecological importance, there is a lack of scientific information concerning metal contamination in TSB marine biota. Thus, we analyzed concentrations of metals in four species of marine benthic organisms (two seaweeds, Padina gymnospora and Sargassum sp. one seagrass, Halodule wrightii and one oyster, Crassostrea rhizophorae in three sites from the TSB region that have been most affected by industrial activities. The concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by Atomic Absorption Spectrophometry. The obtained data indicates that cadmium and copper in seaweeds, oysters and seagrass, as well as Ni concentrations in oysters, were in range of contaminated coastal areas. Cadmium and copper are available to organisms through suspended particles, dissolved fraction of water column and bottom sediment interstitial water. As oysters and other mollusks are used as food sources by the local population, the metal levels found in oysters in TSB may constitute a health risk for this population. Our results suggest implanting a heavy metals biomonitoring program in the TSB marine ecosystems.

Temperature dependent electrical characteristics of an organic-inorganic heterojunction obtained from a novel organometal Mn complex

International Nuclear Information System (INIS)

Ocak, Y.S.; Ebeoglu, M.A.; Topal, G.; Kilicoglu, T.

2010-01-01

This study includes synthesizing a Mn hexaamide (MnHA) organometal compound (C 27 H 21 N 9 O 6 MnCl 2 ).(1/2H 2 O), fabrication of MnHA/n-Si organic-inorganic heterojunction and analysis of conduction mechanism of the device over the room temperature. After synthesizing the molecule, the structure of the compound was determined using spectroscopic methods. The Sn/MnHA/n-Si structure was constructed by forming a thin MnHA layer on n-Si inorganic semiconductor and evaporating Sn metal on organic complex. The structure has shown good rectifying behavior and obeys the thermionic emission theory. The current-voltage (I-V) characteristics of the diode have been measured at temperatures ranging from 300 to 380 K at 10 K intervals to determine the temperature dependent electrical characteristics of the device.

Marsh plant response to metals: Exudation of aliphatic low molecular weight organic acids (ALMWOAs)

Science.gov (United States)

Rocha, A. Cristina S.; Almeida, C. Marisa R.; Basto, M. Clara P.; Vasconcelos, M. Teresa S. D.

2016-03-01

Metal exposure is known to induce the production and secretion of substances, such as aliphatic low molecular weight organic acids (ALMWOAs), into the rhizosphere by plant roots. Knowledge on this matter is extensive for soil plants but still considerably scarce regarding marsh plants roots adapted to high salinity media. Phragmites australis and Halimione portulacoides, two marsh plants commonly distributed in European estuarine salt marshes, were used to assess the response of roots of both species, in terms of ALMWOAs exudation, to Cu, Ni and Cd exposure (isolated and in mixture since in natural environment, they are exposed to mixture of metals). As previous studies were carried out in unrealistic and synthetic media, here a more natural medium was selected. Therefore, in vitro experiments were carried out, with specimens of both marsh plants, and in freshwater contaminated with two different Cu, Ni and Cd concentrations (individual metal and in mixture). Both marsh plants were capable of liberating ALMWOAs into the surrounding medium. Oxalic, citric and maleic acids were found in P. australis root exudate solutions and oxalic and maleic acids in H. portulacoides root exudate solutions. ALMWOA liberation by both plants was plant species and metal-dependent. For instance, Cu affected the exudation of oxalic acid by H. portulacoides and of oxalic and citric acids by P. australis roots. In contrast, Ni and Cd did not stimulate any specific response. Regarding the combination of all metals, H. portulacoides showed a similar response to that observed for Cu individually. However, in the P. australis case, at high metal concentration mixture, a synergetic effect led to the increase of oxalic acid levels in root exudate solution and to a decrease of citric acid liberation. A correlation between ALMWOAs exudation and metal accumulation could not be established. P. australis and H. portulacoides are considered suitable metal phytoremediators of estuarine impacted areas

Effects of humic acid and heavy metals on the sorption of polar and apolar organic pollutants onto biochars.

Science.gov (United States)

Wang, Fei; Sun, Hongwen; Ren, Xinhao; Liu, Yarui; Zhu, Hongkai; Zhang, Peng; Ren, Chao

2017-12-01

The effects of humic acid (HA) and heavy metals (Cu 2+ and Ag + ) on the sorption of polar and apolar organic pollutants onto biochars that were produced at temperatures of 200 °C (BC200) and 700 °C (BC700) were studied. Due to the plentiful polar functional groups on BC200, cationic propranolol exhibited higher levels of sorption than naphthalene on BC200 while naphthalene and propranolol showed similar sorption capacities on BC700. HA changed the characteristics of biochars and generally inhibited the sorption of target organic pollutants on biochars; however, enhancement occurred in some cases depending on the pollutants involved and their concentrations, biochars used and the addition sequences and concentrations of HA. On BC200, HA modifications mainly influenced sorption by decreasing its polarity and increasing its aromaticity, while on BC700, the surface area and pore volume greatly decreased due to the pore-blocking effects of HA. Residue dissolved HA in solution may also contribute to sorption inhibition. Complexation between polar functional groups on BC200 and heavy metals slightly enhanced the sorption of neutral naphthalene and significantly enhanced that of anionic 4-nitro-1-naphtol, while limited the sorption of cationic propranolol. Heavy metals together with their associated water molecules decreased the sorption of target chemicals on BC700 via pore-filling or pore-mouth-covering. Inhibition of heavy metals for 4-nitro-1-naphthol was found to be the weakest due to the bridge effects of heavy metals between 4-nitro-1-naphtol and BC700. The higher polarizability of Ag + led to the increase of its sorption on biochars in the presence of organic aromatic pollutants. The results of the present study shed light on the sorption mechanisms of bi-solute systems and enable us to select suitable biochar sorbents when chemicals co-exist. Copyright © 2017. Published by Elsevier Ltd.

Spectrographic determination of metallic impurities in organic coolants for nuclear reactors

International Nuclear Information System (INIS)

Martin Munoz, M.; Alvarez Gonzalez, F.

1969-01-01

A spectrochemical method for determining metallic impurities in organic coolants for nuclear reactors is given. The organic matter in solid samples is eliminated by controlled distillation and dry ashing in the presence of magnesium oxide as carrier. Liquid, samples are vacuum distillated. The residue is analyzed by carrier distillation and by total burning techniques. The analytical results are discussed and compared with those obtained destroying the organic matter without carrier and using the copper spark technique. (Author) 12 refs

Electrocatalytic Metal-Organic Frameworks for Energy Applications.

Science.gov (United States)

Downes, Courtney A; Marinescu, Smaranda C

2017-11-23

With the global energy demand expected to increase drastically over the next several decades, the development of a sustainable energy system to meet this increase is paramount. Renewable energy sources can be coupled with electrochemical conversion processes to store energy in chemical bonds. To promote these difficult transformations, electrocatalysts that operate at high conversion rates and efficiency are required. Metal-organic frameworks (MOFs) have emerged as a promising class of materials; however, the insulating nature of MOFs has limited their application as electrocatalysts. The recent development of conductive MOFs has led to several electrocatalytic MOFs that display activity comparable to that of the best-performing heterogeneous catalysts. Although many electrocatalytic MOFs exhibit low activity and stability, the few successful examples highlight the possibility of MOF electrocatalysts as replacements for noble-metal-based catalysts in commercial energy-converting devices. We review herein the use of pristine MOFs as electrocatalysts to facilitate important energy-related reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Laser-induced desorption of organic molecules from front- and back-irradiated metal foils

International Nuclear Information System (INIS)

Zinovev, Alexander V.; Veryovkin, Igor V.; Pellin, Michael J.

2009-01-01

Laser-Induced Acoustic Desorption (LIAD) from thin metal foils is a promising technique for gentle and efficient volatilization of intact organic molecules from surfaces of solid substrates. Using the Single Photon Ionization (SPI) method combined with time-of-flight mass-spectrometry (TOF MS), desorbed flux in LIAD was examined and compared to that from direct laser desorption (LD). Molecules of various organic dyes were used in experiments. Translational velocities of the desorbed intact molecules did not depend on the desorbing laser intensity, which implies the presence of more sophisticated mechanism of energy transfer than the direct mechanical or thermal coupling between the laser pulse and the adsorbed molecules. The results of our experiments indicate that the LIAD phenomenon cannot be described in terms of a simple mechanical shake-off nor the direct laser desorption. Rather, they suggest that multi-step energy transfer processes are involved. Possible qualitative mechanism of LIAD that are based on formation of non-equilibrium energy states in the adsorbate-substrate system are proposed and discussed.

Dependence of the Rossby number on helium and metal abundances

International Nuclear Information System (INIS)

Rucinski, S.M.; Vandenberg, D.A.

1990-01-01

Convective turnover times, tau, are calculated for solar-type stars of the zero-age main-sequence models of VandenBerg and Poll (1989) with helium abundances = 0.22, 0.27, and 0.32 and metal abundances = 0.0169, 0.024, and 0.03. Emphasis is given to the possible dependence of turnover times on the chemical composition of a star. It is found that deviations in log tau from a mean dependence on the (B-V) color are less than + or - 0.1. Thus, the predicted shape of the log tau vs. (B-V) relation is quite robust. 15 refs

HDR monotherapy for prostate cancer: A simulation study to determine the effect of catheter displacement on target coverage and normal tissue irradiation

International Nuclear Information System (INIS)

Kolkman-Deurloo, Inger-Karine K.; Roos, Martin A.; Aluwini, Shafak

2011-01-01

Purpose: The aim of this study was to systematically analyse the effect of catheter displacements both on target coverage and normal tissue irradiation in fractionated high dose rate (HDR) prostate brachytherapy, using a simulation study, and to define tolerances for catheter displacement ensuring that both target coverage and normal tissue doses remain clinically acceptable. Besides the effect of total implant displacement, also displacements of catheters belonging to selected template rows only were evaluated in terms of target coverage and normal tissue dose, in order to analyse the change in dose distribution as a function of catheter dwell weight and catheter location. Material and methods: Five representative implant geometries, with 17 catheters each, were selected. The clinical treatment plan was compared to treatment plans in which an entire implant displacement in caudal direction over 3, 5, 7 and 10 mm was simulated. Besides, treatment plans were simulated considering a displacement of either the central, most ventral or most dorsal catheter rows only, over 5 mm caudally. Results: Due to displacement of the entire implant the target coverage drops below the tolerance of 93% for all displacements studied. The effect of displacement of the entire implant on organs at risk strongly depended on the patient anatomy; e.g., for 80% of the implant geometries the V 80 of the rectum exceeded its tolerance for all displacements. The effect of displacement of catheters belonging to selected template rows depended strongly on the relative weight of each catheter row when considering the target coverage and on its location when considering the dose in the organs at risk. Conclusion: This study supports the need for a check of the catheter locations before each fraction and correction of deviations of the catheter position exceeding 3 mm.

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Science.gov (United States)

2010-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b Protection of Environment... Constructed on or Before September 20, 1994 § 60.33b Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals...

Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.

Science.gov (United States)

Lemaire, Paul C; Zhao, Junjie; Williams, Philip S; Walls, Howard J; Shepherd, Sarah D; Losego, Mark D; Peterson, Gregory W; Parsons, Gregory N

2016-04-13

Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.

Metal mobilization from metallurgical wastes by soil organic acids.

Science.gov (United States)

Potysz, Anna; Grybos, Malgorzata; Kierczak, Jakub; Guibaud, Gilles; Fondaneche, Patrice; Lens, Piet N L; van Hullebusch, Eric D

2017-07-01

Three types of Cu-slags differing in chemical and mineralogical composition (historical, shaft furnace, and granulated slags) and a matte from a lead recovery process were studied with respect to their susceptibility to release Cu, Zn and Pb upon exposure to organic acids commonly encountered in soil environments. Leaching experiments (24-960 h) were conducted with: i) humic acid (20 mg/L) at pH t 0  = 4.4, ii) fulvic acid (20 mg/L) at pH t 0  = 4.4, iii) an artificial root exudates (ARE) (17.4 g/L) solution at pH t 0  = 4.4, iv) ARE solution at pH t 0  = 2.9 and v) ultrapure water (pH t 0  = 5.6). The results demonstrated that the ARE contribute the most to the mobilization of metals from all the wastes analyzed, regardless of the initial pH of the solution. For example, up to 14%, 30%, 24% and 5% of Cu is released within 960 h from historical, shaft furnace, granulated slags and lead matte, respectively, when exposed to the artificial root exudates solution (pH 2.9). Humic and fulvic acids were found to have a higher impact on granulated and shaft furnace slags as compared to the ultrapure water control and increased the release of metals by a factor up to 37.5 (Pb) and 20.5 (Cu) for granulated and shaft furnace slags, respectively. Humic and fulvic acids amplified the mobilization of metals by a maximal factor of 13.6 (Pb) and 12.1 (Pb) for historical slag and lead matte, respectively. The studied organic compounds contributed to different release rates of metallic contaminants from individual metallurgical wastes under the conditions tested. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sensitivity of postplanning target and OAR coverage estimates to dosimetric margin distribution sampling parameters.

Science.gov (United States)

Xu, Huijun; Gordon, J James; Siebers, Jeffrey V

2011-02-01

A dosimetric margin (DM) is the margin in a specified direction between a structure and a specified isodose surface, corresponding to a prescription or tolerance dose. The dosimetric margin distribution (DMD) is the distribution of DMs over all directions. Given a geometric uncertainty model, representing inter- or intrafraction setup uncertainties or internal organ motion, the DMD can be used to calculate coverage Q, which is the probability that a realized target or organ-at-risk (OAR) dose metric D, exceeds the corresponding prescription or tolerance dose. Postplanning coverage evaluation quantifies the percentage of uncertainties for which target and OAR structures meet their intended dose constraints. The goal of the present work is to evaluate coverage probabilities for 28 prostate treatment plans to determine DMD sampling parameters that ensure adequate accuracy for postplanning coverage estimates. Normally distributed interfraction setup uncertainties were applied to 28 plans for localized prostate cancer, with prescribed dose of 79.2 Gy and 10 mm clinical target volume to planning target volume (CTV-to-PTV) margins. Using angular or isotropic sampling techniques, dosimetric margins were determined for the CTV, bladder and rectum, assuming shift invariance of the dose distribution. For angular sampling, DMDs were sampled at fixed angular intervals w (e.g., w = 1 degree, 2 degrees, 5 degrees, 10 degrees, 20 degrees). Isotropic samples were uniformly distributed on the unit sphere resulting in variable angular increments, but were calculated for the same number of sampling directions as angular DMDs, and accordingly characterized by the effective angular increment omega eff. In each direction, the DM was calculated by moving the structure in radial steps of size delta (=0.1, 0.2, 0.5, 1 mm) until the specified isodose was crossed. Coverage estimation accuracy deltaQ was quantified as a function of the sampling parameters omega or omega eff and delta. The

Self-assembly of metal-organic supramolecules: from a metallamacrocycle and a metal-organic coordination cage to 1D or 2D coordination polymers based on flexible dicarboxylate ligands.

Science.gov (United States)

Dai, Fangna; Dou, Jianmin; He, Haiyan; Zhao, Xiaoliang; Sun, Daofeng

2010-05-03

To assemble metal-organic supramolecules such as a metallamacrocycle and metal-organic coordination cage (MOCC), a series of flexible dicarboxylate ligands with the appropriate angle, 2,2'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H(2)L(1)), 2,2'-(2,5-dimethyl-1,4-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H(2)L(2)), 2,2'-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl)dinicotinic acid (H(2)L(3)), and 2,2'-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H(2)L(4)), have been designed and synthesized. Using these flexible ligands to assemble with metal ions, six metal-organic supramolecules, Cd(2)(L(1))(2)(dmf)(4)(H(2)O)(2).H(2)O (1), Mn(3)((1)L(2))(2)((2)L(2))(dmf)(2)(H(2)O)(2).5dmf (2), Cu(4)(L(3))(4)(H(2)O)(4).3dmf (3), Cu(4)(L(4))(4)(dmf)(2)(EtOH)(2).8dmf.6H(2)O (4), Mn(4)(L(4))(4)(dmf)(4)(H(2)O)(4).6dmf.H(2)O (5), and Mn(3)(L(4))(3)(dmf)(4).2dmf.3H(2)O (6), possessing a rectangular macrocycle, MOCCs or their extensions, and 1D or 2D coordination polymers, have been isolated. All complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex 1 is a discrete rectangular macrocycle, while complex 2 is a 2D macrocycle-based coordination polymer in which the L(2) ligand adopts both syn and anti conformations. Complexes 3-5 are discrete MOCCs in which two binuclear metal clusters are engaged by four organic ligands. The different geometries of the secondary building units (SBUs) and the axial coordinated solvates on the SBUs result in their different symmetries. Complex 6 is a 1D coordination polymer, extended from a MOCC made up of two metal ions and three L(4) ligands. All of the flexible dicarboxylate ligands adopt a syn conformation except that in complex 2, indicating that the syn conformational ligand is helpful for the formation of a metallamacrocycle and a MOCC. The magnetic properties of complexes 5

Band mapping of surface states vs. adsorbate coverage

International Nuclear Information System (INIS)

Rotenberg, E.; Kevan, S.D.; Denlinger, J.D.; Chung, Jin-Wook

1997-01-01

The theory of electron bands, which arises from basic quantum mechanical principles, has been the cornerstone of solid state physics for over 60 years. Simply put, an energy band is an electron state in a solid whose energy varies with its momentum (similar to, but with a more complicated dependence than, how a free electron's energy is proportional to its momentum squared). Much attention over the last 15 years has been given to the study of band structure of surfaces and interfaces, especially as the applications of these two-dimensional systems have become increasingly important to industry and science. The ultraESCA endstation at beamline 7.01 at the Advanced Light Source was developed for very high-energy - (∼50 meV) and angular - ( 12 photons/sec) makes the detailed study of the evolution of bands possible. The authors are interested in learning how, when one forms a chemical bond between a metal and an overlaying atom or molecule, the resulting charge transfer to or from the adsorbate affects the surface bands. In some cases of interest, intermediate coverages lead to different band structure than at the extremes of clean and saturated surfaces. Surfaces of tungsten are particularly interesting, as their atomic geometry has been shown to be exquisitely sensitive to both the surface vibrational and electronic properties. In this study, the authors looked at the surface bands of tungsten ((110) surface), as a function both of coverage and mass of overlaying atoms. The adsorbed atoms were hydrogen and the alkali atoms lithium and cesium

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...

Postsynthetic Tuning of Metal-Organic Frameworks for Targeted Applications.

Science.gov (United States)

Islamoglu, Timur; Goswami, Subhadip; Li, Zhanyong; Howarth, Ashlee J; Farha, Omar K; Hupp, Joseph T

2017-04-18

Metal-organic frameworks (MOFs) are periodic, hybrid, atomically well-defined porous materials that typically form by self-assembly and consist of inorganic nodes (metal ions or clusters) and multitopic organic linkers. MOFs as a whole offer many intriguing properties, including ultrahigh porosity, tunable chemical functionality, and low density. These properties point to numerous potential applications, including gas storage, chemical separations, catalysis, light harvesting, and chemical sensing, to name a few. Reticular chemistry, or the linking of molecular building blocks into predetermined network structures, has been employed to synthesize thousands of MOFs. Given the vast library of candidate nodes and linkers, the number of potentially synthetically accessible MOFs is enormous. Nevertheless, a powerful complementary approach to obtain specific structures with desired chemical functionality is to modify known MOFs after synthesis. This approach is particularly useful when incorporation of particular chemical functionalities via direct synthesis is challenging or impossible. The challenges may stem from limited stability or solubility of precursors, unwanted secondary reactivity of precursors, or incompatibility of functional groups with the conditions needed for direct synthesis. MOFs can be postsynthetically modified by replacing the metal nodes and/or organic linkers or via functionalization of the metal nodes and/or organic linkers. Here we describe some of our efforts toward the development and application of postsynthetic strategies for imparting desired chemical functionalities in MOFs of known topology. The techniques include methods for functionalizing MOF nodes, i.e., solvent-assisted ligand incorporation (SALI) and atomic layer deposition in MOFs (AIM) as well as a method to replace structural linkers, termed solvent-assisted linker exchange (SALE), also known as postsynthethic exchange (PSE). For each functionalization strategy, we first describe

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

OpenAIRE

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

2014-01-01

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

Atomistic Origin of Rate-Dependent Serrated Plastic Flow in Metallic Glasses

Directory of Open Access Journals (Sweden)

Yao YG

2008-01-01

Full Text Available Abstract Nanoindentation simulations on a binary metallic glass were performed under various strain rates by using molecular dynamics. The rate-dependent serrated plastic flow was clearly observed, and the spatiotemporal behavior of its underlying irreversible atomic rearrangement was probed. Our findings clearly validate that the serration is a temporally inhomogeneous characteristic of such rearrangements and not directly dependent on the resultant shear-banding spatiality. The unique spatiotemporal distribution of shear banding during nanoindentation is highlighted in terms of the potential energy landscape (PEL theory.

Biosolids and heavy metals in soils

Directory of Open Access Journals (Sweden)

Silveira Maria Lucia Azevedo

2003-01-01

Full Text Available The application of sewage sludge or biosolids on soils has been widespread in agricultural areas. However, depending on their characteristics, they may cause increase in heavy metal concentration of treated soils. In general, domestic biosolids have lower heavy metal contents than industrial ones. Origin and treatment method of biosolids may markedly influence their characteristics. The legislation that controls the levels of heavy metal contents in biosolids and the maximum concentrations in soils is still controversial. In the long-term, heavy metal behavior after the and of biosolid application is still unknown. In soils, heavy metals may be adsorbed via specific or non-specific adsorption reactions. Iron oxides and organic matter are the most important soil constituents retaining heavy metals. The pH, CEC and the presence of competing ions also affect heavy metal adsorption and speciation in soils. In solution, heavy metals can be present either as free-ions or complexed with organic and inorganic ligands. Generally, free-ions are more relevant in environmental pollution studies since they are readily bioavailable. Some computer models can estimate heavy metal activity in solution and their ionic speciation. Thermodynamic data (thermodynamic stability constant, total metal and ligand concentrations are used by the GEOCHEM-PC program. This program allows studying heavy metal behavior in solution and the effect of changes in the conditions, such as pH and ionic strength and the application of organic and inorganic ligands caused by soil fertilization.

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

Size and shape dependent lattice parameters of metallic nanoparticles

International Nuclear Information System (INIS)

Qi, W. H.; Wang, M. P.

2005-01-01

A model is developed to account for the size and shape dependent lattice parameters of metallic nanoparticles, where the particle shape difference is considered by introducing a shape factor. It is predicted that the lattice parameters of nanoparticles in several nanometers decrease with decreasing of the particle size, which is consistent with the corresponding experimental results. Furthermore, it is found that the particle shape can lead to 10% of the total lattice variation. The model is a continuous media model and can deal with the nanoparticles larger than 1 nm. Since the shape factor approaches to infinity for nanowires and nanofilms, therefore, the model cannot be generalized to the systems of nanowires and nanofilms. For the input parameters are physical constants of bulk materials, therefore, the present model may be used to predict the lattice variation of different metallic nanoparticles with different lattice structures

Metal Speciation in Landfill Leachates with a Focus on the Influence of Organic Matter

Energy Technology Data Exchange (ETDEWEB)

F Claret; C Tournassat; C Crouzet; E Gaucher; T Schäfer; G Braibant; D Guyonnet

2011-12-31

This study characterizes the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmosphere to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc are super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed.

Interactive computation of coverage regions for indoor wireless communication

Science.gov (United States)

Abbott, A. Lynn; Bhat, Nitin; Rappaport, Theodore S.

1995-12-01

This paper describes a system which assists in the strategic placement of rf base stations within buildings. Known as the site modeling tool (SMT), this system allows the user to display graphical floor plans and to select base station transceiver parameters, including location and orientation, interactively. The system then computes and highlights estimated coverage regions for each transceiver, enabling the user to assess the total coverage within the building. For single-floor operation, the user can choose between distance-dependent and partition- dependent path-loss models. Similar path-loss models are also available for the case of multiple floors. This paper describes the method used by the system to estimate coverage for both directional and omnidirectional antennas. The site modeling tool is intended to be simple to use by individuals who are not experts at wireless communication system design, and is expected to be very useful in the specification of indoor wireless systems.

Versatile Surface Functionalization of Metal-Organic Frameworks through Direct Metal Coordination with a Phenolic Lipid Enables Diverse Applications

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wei [Univ. of New Mexico, Albuquerque, NM (United States); Xiang, Guolei [Univ. of Cambridge (United Kingdom); Shang, Jin [Univ. of Hong Kong (China); Guo, Jimin [Univ. of New Mexico, Albuquerque, NM (United States); Motevalli, Benyamin [Monash Univ., Clayton, VIC (Australia); Durfee, Paul [Univ. of New Mexico, Albuquerque, NM (United States); Agola, Jacob Ongudi [Univ. of New Mexico, Albuquerque, NM (United States); Coker, Eric N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brinker, C. Jeffrey [Univ. of New Mexico, Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2018-02-22

Here, a novel strategy for the versatile functionalization of the external surface of metal-organic frameworks (MOFs) has been developed based on the direct coordination of a phenolic-inspired lipid molecule DPGG (1,2-dipalmitoyl-sn-glycero-3-galloyl) with metal nodes/sites surrounding MOF surface. X-ray diffraction and Argon sorption analysis prove that the modified MOF particles retain their structural integrity and porosity after surface modification. Density functional theory calculations reveal that strong chelation strength between the metal sites and the galloyl head group of DPGG is the basic prerequisite for successful coating. Due to the pH-responsive nature of metal-phenol complexation, the modification process is reversible by simple washing in weak acidic water, showing an excellent regeneration ability for water-stable MOFs. Moreover, the colloidal stability of the modified MOFs in the nonpolar solvent allows them to be further organized into 2 dimensional MOF or MOF/polymer monolayers by evaporation-induced interfacial assembly conducted on an air/water interface. Lastly, the easy fusion of a second functional layer onto DPGG-modified MOF cores, enabled a series of MOF-based functional nanoarchitectures, such as MOFs encapsulated within hybrid supported lipid bilayers (so-called protocells), polyhedral core-shell structures, hybrid lipid-modified-plasmonic vesicles and multicomponent supraparticles with target functionalities, to be generated. for a wide range of applications.

Organic substrates as electron donors in permeable reactive barriers for removal of heavy metals from acid mine drainage.

Science.gov (United States)

Kijjanapanich, P; Pakdeerattanamint, K; Lens, P N L; Annachhatre, A P

2012-12-01

This research was conducted to select suitable natural organic substrates as potential carbon sources for use as electron donors for biological sulphate reduction in a permeable reactive barrier (PRB). A number of organic substrates were assessed through batch and continuous column experiments under anaerobic conditions with acid mine drainage (AMD) obtained from an abandoned lignite coal mine. To keep the heavy metal concentration at a constant level, the AMD was supplemented with heavy metals whenever necessary. Under anaerobic conditions, sulphate-reducing bacteria (SRB) converted sulphate into sulphide using the organic substrates as electron donors. The sulphide that was generated precipitated heavy metals as metal sulphides. Organic substrates, which yielded the highest sulphate reduction in batch tests, were selected for continuous column experiments which lasted over 200 days. A mixture of pig-farm wastewater treatment sludge, rice husk and coconut husk chips yielded the best heavy metal (Fe, Cu, Zn and Mn) removal efficiencies of over 90%.

Temperature-dependent thermo-elastic properties of s-, p- and d-block liquid metals

International Nuclear Information System (INIS)

Singh, R.N.; Arafin, S.; George, A.K.

2007-01-01

Thermodynamic relations involving experimentally known physical quantities are used to determine the ratio of specific heats, γ, for s-block (Na, K, Rb, Cs, Mg), d-block (Fe, Co, Ni, Cu, Ag, Au, Zn, Cd, Hg,) and p-block (Al, Ga, In, Tl, Sn, Pb, Sb, Bi, Se, Te) liquid metals. γ is further utilized to determine reliable values for the isothermal compressibility (κ T ) and the specific heat at constant volume (C V ) for these liquid metals near and above the melting temperatures. These data are of considerable significance for various thermo-physical analysis of liquid metals. We have also evaluated the Grueneisen function and its temperature dependence to establish the correlation between the thermal expansion and the elastic response to thermally induced stress. The values of acoustic impedance for liquid metals are evaluated and its physical significance is discussed for the transmission of elastic waves across metallic interfaces

Pristine Metal-Organic Frameworks and their Composites for Energy Storage and Conversion.

Science.gov (United States)

Liang, Zibin; Qu, Chong; Guo, Wenhan; Zou, Ruqiang; Xu, Qiang

2017-11-22

Metal-organic frameworks (MOFs), a new class of crystalline porous organic-inorganic hybrid materials, have recently attracted increasing interest in the field of energy storage and conversion. Herein, recent progress of MOFs and MOF composites for energy storage and conversion applications, including photochemical and electrochemical fuel production (hydrogen production and CO 2 reduction), water oxidation, supercapacitors, and Li-based batteries (Li-ion, Li-S, and Li-O 2 batteries), is summarized. Typical development strategies (e.g., incorporation of active components, design of smart morphologies, and judicious selection of organic linkers and metal nodes) of MOFs and MOF composites for particular energy storage and conversion applications are highlighted. A broad overview of recent progress is provided, which will hopefully promote the future development of MOFs and MOF composites for advanced energy storage and conversion applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioleaching of heavy metals from soil using fungal-organic acids : bench scale testing

Energy Technology Data Exchange (ETDEWEB)

Cathum, S.J.; Ousmanova, D.; Somers, A.; Punt, M. [SAIC Canada, Ottawa, ON (Canada); Brown, C.E. [Environment Canada, Ottawa, ON (Canada). Emergencies Engineering Division]|[Environment Canada, Ottawa, ON (Canada). Environmental Technology Centre

2006-07-01

The ability of fungi to solubilize metals from solid materials may present new opportunities in environmental remediation. This paper presented details of a bench scale experiment that evaluated the leaching of heavy metals from contaminated soil using in situ fungal-generated organic acids. Rice was used as the growing media for organic acid production by A. foetidus. The cultivated fungus was placed on large pieces of potato-dextrose agar (PDA) plates and suspended in 5 L of sterilized water. The cooked rice was inoculated by pouring the 5 L spore suspension over the rice layer. Soil was obtained from a soil pile impacted with heavy metals at a private industrial site and augmented with Pb-contaminated soil. A polyethylene tub was used with a drain pipe leading to a leachate vessel. Crushed stone was spread over the bottom of the tub to assist leachate drainage. Approximately 45 kg of the contaminated soil was spread evenly over the stone layer to a depth of 10 cm. The concentrated spore suspension was sprinkled over the rice. Each week the leachate collection vessel was removed from the bioleaching system and the fine soil particles were allowed to settle. A control was run using the contaminated soil and solid substrate without fungus. Growth of A. foetidus was observed in both control experiment and test experiment after a period of 35 days. The pH of the leachate was measured as the fungal growth progressed. The process was assessed using ICP Mass Spectroscopy and electron spectroscopy, which showed that approximately 65 g of heavy metals were mobilized from 45 kg of soil, and that the biological leaching process resulted in greater mobilization of heavy metals relative to the control experiment. It was concluded that organic acids generated by A. foetidus were capable of leaching heavy metals from the soil. 30 refs., 4 tabs., 15 figs.

Applications of Total Scattering & Pair Distribution Function Analysis in Metal-Organic Framework Materials

DEFF Research Database (Denmark)

Xu, Hui; Birgisson, Steinar; Sommer, Sanna

structure. At the same time, there is an ongoing debate on whether the SBU is present prior, or during MOF crystallization in MOF chemistry. However, little is known about MOFs formation mechanism. Currently techniques to study the in situ MOF formation process mainly focused on after......-crystallization process, for example in situ XRD and SAXS/WAXS study on MOF formation. However, the pre-crystallization process in the early stage of MOF formation is still unexplored. In this project, total scattering and PDF study will be carried out to explore the MOF formation process in early stage. This includes......Metal-Organic Frameworks (MOFs) is constructed by metal-oxide nodes and organic ligands. The formation of different structures of metal-oxide nodes (also called secondary building units, SBU) is crucial for MOF final structures, because the connectivity of SBU greatly influence the final MOF...

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.

Phase-coherent electron transport through metallic atomic-sized contacts and organic molecules

Energy Technology Data Exchange (ETDEWEB)

Pauly, F.

2007-02-02

This work is concerned with the theoretical description of systems at the nanoscale, in particular the electric current through atomic-sized metallic contacts and organic molecules. In the first part, the characteristic peak structure in conductance histograms of different metals is analyzed within a tight-binding model. In the second part, an ab-initio method for quantum transport is developed and applied to single-atom and single-molecule contacts. (orig.)

Manufacture of highly loaded silica-supported cobalt Fischer–Tropsch catalysts from a metal organic framework

KAUST Repository

Sun, Xiaohui

2017-11-16

The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades. Independently controlling metal loading, nanoparticle size, distribution, and accessibility has proven challenging because of the clear interdependence between these crucial performance parameters. Here we present a stepwise methodology that, making use of a cobalt-containing metal organic framework as hard template (ZIF-67), allows addressing this long-standing challenge. Condensation of silica in the Co-metal organic framework pore space followed by pyrolysis and subsequent calcination of these composites renders highly loaded cobalt nanocomposites (~ 50 wt.% Co), with cobalt oxide reducibility in the order of 80% and a good particle dispersion, that exhibit high activity, C5 + selectivity and stability in Fischer-Tropsch synthesis.

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.

On the necessity of composition-dependent low-temperature opacity in models of metal-poor asymptotic giant branch stars

Energy Technology Data Exchange (ETDEWEB)

Constantino, Thomas; Campbell, Simon; Lattanzio, John [Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Victoria 3800 (Australia); Gil-Pons, Pilar, E-mail: thomas.constantino@monash.edu [Department of Applied Physics, Polytechnic University of Catalonia, 08860 Barcelona (Spain)

2014-03-20

The vital importance of composition-dependent low-temperature opacity in low-mass (M ≤ 3 M {sub ☉}) asymptotic giant branch (AGB) stellar models of metallicity Z ≥ 0.001 has recently been demonstrated. Its significance to more metal-poor, intermediate-mass (M ≥ 2.5 M {sub ☉}) models has yet to be investigated. We show that its inclusion in lower-metallicity models ([Fe/H] ≤–2) is essential and that there exists no threshold metallicity below which composition-dependent molecular opacity may be neglected. We find it to be crucial in all intermediate-mass models investigated ([Fe/H] ≤–2 and 2.5 ≤ M/M {sub ☉} ≤ 5), because of the evolution of the surface chemistry, including the orders of magnitude increase in the abundance of molecule-forming species. Its effect on these models mirrors that previously reported for higher-metallicity models—increase in radius, decrease in T {sub eff}, faster mass loss, shorter thermally pulsing AGB lifetime, reduced enrichment in third dredge-up products (by a factor of 3-10), and an increase in the mass limit for hot bottom burning. We show that the evolution of low-metallicity models with composition-dependent low-temperature opacity is relatively independent of initial metal abundance because its contribution to the opacity is far outweighed by changes resulting from dredge-up. Our results imply a significant reduction in the expected number of nitrogen-enhanced metal-poor stars, which may help explain their observed paucity. We note that these findings are partially a product of the macrophysics adopted in our models, in particular, the Vassiliadis and Wood mass loss rate which is strongly dependent on radius.

Sorption of heavy metals and radionuclides on mineral surfaces in the presence of organic co-contaminants. 1997 annual progress report

International Nuclear Information System (INIS)

Leckie, J.; Redden, G.

1997-01-01

metal or the rates of changes in partitioning as a consequence of ligand or metal exchange. Formation of metal ion-ligand-oxide surface ternary complexes can enhance sorption in some cases while highly stable metal-organic complexes in solution will decrease sorption. The preference for these two cases depends on the relative chemical properties of each component as well as system parameters such as pH and ionic strength and the relative reaction rates. In general, there is a fundamental absence of the experimental observations needed to establish the trends needed for predictive modeling and technological developments. If the authors can understand both the equilibrium partitioning in these ternary systems (i.e., metal-ligand-solid) and the types of complexes that form as functions of a set of measurable parameters that characterize the system, the authors should significantly improve the ability to estimate the mass transport rates of contaminants and natural solutes in aquifers and water columns where organic ligands are significant species. The authors will also be better prepared to devise remediation strategies where introduction of organic ligands can bring about either mobilization of contaminants or enhanced retardation. The ligands are likely to prove useful in the direct treatment and remediation of contaminated sites (Francis and Dodge, 1992; Tuin and Tels, 1990) and can be chosen for their long term stability or their ability to degrade by natural biotic processes.'

Stability of metal organic frameworks and interaction of small gas molecules in these materials

Science.gov (United States)

Tan, Kui

The work in this dissertation combines spectroscopy ( in-situ infrared absorption and Raman), powder X-ray diffraction and DFT calculations to study the stability of metal organic frameworks materials (MOFs) in the presence of water vapor and other corrosive gases (e.g., SO 2, NO2 NO), and the interaction and competitive co-adsorption of several gases within MOFs by considering two types of prototypical MOFs: 1) a MOF with saturated metal centers based on paddlewheel secondary building units: M(bdc)(ted)0.5 [M=Cu, Zn, Ni, Co, bdc = 1,4-benzenedicarboxylate, ted = triethylenediamine], and 2) a MOF with unsaturated metal centers: M2(dobdc) [M=Mg2+, Zn2+, Ni2+, Co2+ and dobdc = 2,5-dihydroxybenzenedicarboxylate]. We find that the stability of MOFs to water vapor critically depends on their structure and the specific metal cation in the building units. For M(bdc)(ted)0.5, the metal-bdc bond is the most vulnerable for Cu(bdc)(ted)0.5, while the metal-ted bond is first attacked for the Zn and Co analogs. In contrast, Ni(bdc)(ted)0.5 remains stable under the same conditions. For M2(dobdc), or MOF-74, the weak link is the dobdc-metal bond. The water molecule is dissociatively adsorbed at the metal-oxygen group with OH adsorption directly on the metal center and H adsorption on the bridging O of the phenolate group in the dobdc linker. Other technologically important molecules besides water, such as NO, NO2, SO2, tend to poison M2(dobdc) through dissociative or molecular adsorption onto the open metal sites. A high uptake SO2 capacity was measured in M(bdc)(ted)0.5, attributed to multipoint interactions between the guest SO2 molecule and the MOF host. In the case of competitive co-adsorption between CO2 and other small molecules, we find that binding energy alone is not a good indicator of molecular site occupation within the MOF (i.e., it cannot successfully predict and evaluate the displacement of CO2 by other molecules). Instead, we show that the kinetic barrier for the

MATERIAL DEPENDENCE OF TEMPERATURE DISTRIBUTION IN MULTI-LAYER MULTI-METAL COOKWARE

Directory of Open Access Journals (Sweden)

MOHAMMADREZA SEDIGH

2017-09-01

Full Text Available Laminated structure is becoming more popular in cookware markets; however, there seems to be a lack of enough scientific studies to evaluate its pros and cons, and to show that how it functions. A numerical model using a finite element method with temperature-dependent material properties has been performed to investigate material and layer dependence of temperature distribution in multi-layer multi-metal plate exposed to irregular heating. Behavior of two parameters including mean temperature value and uniformity on the inner surface of plate under variations of thermal properties and geometrical conditions have been studied. The results indicate that conductive metals used as first layer in bi-layer plates have better thermal performance than those used in the second layer. In addition, since cookware manufacturers increasingly prefer to use all-clad aluminium plate, recently, this structure is analysed in the present study as well. The results show all-clad copper and aluminum plate possesses lower temperature gradient compared with single layer aluminum and all-clad aluminum core plates.

Performance Enhancement of Organic Light-Emitting Diodes Using Electron-Injection Materials of Metal Carbonates

Science.gov (United States)

Shin, Jong-Yeol; Kim, Tae Wan; Kim, Gwi-Yeol; Lee, Su-Min; Shrestha, Bhanu; Hong, Jin-Woong

2016-05-01

Performance of organic light-emitting diodes was investigated depending on the electron-injection materials of metal carbonates (Li2CO3 and Cs2CO3 ); and number of layers. In order to improve the device efficiency, two types of devices were manufactured by using the hole-injection material (Teflon-amorphous fluoropolymer -AF) and electron-injection materials; one is a two-layer reference device ( ITO/Teflon-AF/Alq3/Al ) and the other is a three-layer device (ITO/Teflon-AF/Alq3/metal carbonate/Al). From the results of the efficiency for the devices with hole-injection layer and electron-injection layer, it was found that the electron-injection layer affects the electrical properties of the device more than the hole-injection layer. The external-quantum efficiency for the three-layer device with Li2CO3 and Cs2CO3 layer is improved by approximately six and eight times, respectively, compared with that of the two-layer reference device. It is thought that a use of electron-injection layer increases recombination rate of charge carriers by the active injection of electrons and the blocking of holes.

Surface metal adsorption on zooplankton carapaces: implications for exposure and effects in consumer organisms

International Nuclear Information System (INIS)

Robinson, K.A.; Baird, D.J.; Wrona, F.J.

2003-01-01

Metals adsorbed to prey surfaces may be a mechanism of exposure in predators. - The current study aimed to determine the potential of two important aquatic invertebrate crustacean species, Daphnia magna and Ceriodaphnia dubia, to adsorb cadmium on to their carapaces from aqueous solution. Using the Langmuir equation to model data outputs, it was shown that cadmium readily became associated with the carapace surfaces of both species, with uptake being dependent on exposure time and concentration. Maximum carapace-adsorption potential was found to be directly related to surface area, so that at predicted carapace saturation, D. magna neonates bound approximately five times more cadmium than the smaller C. dubia neonates. However, adsorption per unit surface area was found to be similar under the same exposure conditions. Results of surface metal adsorption studies in C. dubia suggested that short term exposures to high concentrations of aqueous cadmium would lead to similar levels of adsorption as obtained with long-term exposures to low concentrations. The study illustrates that contaminants adsorbed to prey surfaces may be an important mechanism of exposure to predators, and highlights some potential problems of feeding organisms during long-term toxicity tests

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.

Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition.

Science.gov (United States)

Tao, Weiwei; Cao, Penghui; Park, Harold S

2018-04-30

Understanding the time-dependent mechanical behavior of nanomaterials such as nanowires is essential to predict their reliability in nanomechanical devices. This understanding is typically obtained using creep tests, which are the most fundamental loading mechanism by which the time-dependent deformation of materials is characterized. However, due to existing challenges facing both experimentalists and theorists, the time-dependent mechanical response of nanowires is not well-understood. Here, we use atomistic simulations that can access experimental time scales to examine the creep of single crystal FCC metal (Cu, Ag, Pt) nanowires. We report that both Cu and Ag nanowires show significantly increased ductility and superplasticity under low creep stresses, where the superplasticity is driven by a rate-dependent transition in defect nucleation from twinning to trailing partial dislocations at the micro or millisecond timescale. The transition in deformation mechanism also governs a corresponding transition in the stress-dependent creep time at the microsecond (Ag) and millisecond (Cu) timescales. Overall, this work demonstrates the necessity of accessing timescales that far exceed those seen in conventional atomistic modeling for accurate insights into the time-dependent mechanical behavior and properties of nanomaterials.

Correlation between temperature dependence of elastic moduli and Debye temperature of paramagnetic metal

International Nuclear Information System (INIS)

Bodryakov, V.Yu.; Povzner, A.A.

2000-01-01

The correlation between the temperature dependence of elastic moduli and the Debye temperature of paramagnetic metal is analyzed in neglect of the temperature dependence of the Poison coefficient σ within the frames of the Debye-Grueneisen presentations. It is shown, that namely the temperature dependence of the elastic moduli determines primarily the temperature dependence of the Debye temperature Θ(T). On the other hand, the temperature dependence Θ(T) very weakly effects the temperature dependence of the elastic moduli. The later made it possible to formulate the self-consistent approach to calculation of the elastic moduli temperature dependence. The numerical estimates of this dependence parameters are conducted by the example of the all around compression modulus of the paramagnetic lutetium [ru

The trace metals accumulation in marine organisms of the southeastern Adriatic coast, Montenegro

Directory of Open Access Journals (Sweden)

Joksimovic Danijela

2012-01-01

Full Text Available The concentration and accumulation of trace metals (Co, Ni, As, Cd, Pb and Hg were measured in sea water, sediments and marine organisms in the coastline of the Montenegro. The obtained results of trace metals in seagrass and mussels were compared with those found in the water column and sediment. Sampling was performed in the fall of 2005 at five locations in the Montenegrin coastline, Sveta Stasija, Herceg Novi, Zanjice, Budva and Bar, which present different levels and sources of human impact. The heavy metals analyses in seawater, sediment, P. oceanica and M. galloprovincialis identified the harbor of Bar as the most Hg-contaminated site, Zanjice as the most As contaminated and Sveta Stasija as the most Pb-contaminated areas of the Montenegrin coastal area. This study showed that P. oceanica may have a greater bioaccumulation capacity than M. galloprovincialis for the considered metals, except for As and Hg, and both organisms may reflect contamination in the water column and in the sediment. For the first time, seagrass P. oceanica and M. galloprovincialis were employed as metal bioindicators for the southeastern Adriatic. The results of this study could serve as a baseline in the future for the assessment of anthropogenic effects in this marine ecosystem.

Buried MoO x/Ag Electrode Enables High-Efficiency Organic/Silicon Heterojunction Solar Cells with a High Fill Factor.

Science.gov (United States)

Xia, Zhouhui; Gao, Peng; Sun, Teng; Wu, Haihua; Tan, Yeshu; Song, Tao; Lee, Shuit-Tong; Sun, Baoquan

2018-04-25

Silicon (Si)/organic heterojunction solar cells based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n-type Si have attracted wide interests because they promise cost-effectiveness and high-efficiency. However, the limited conductivity of PEDOT:PSS leads to an inefficient hole transport efficiency for the heterojunction device. Therefore, a high dense top-contact metal grid electrode is required to assure the efficient charge collection efficiency. Unfortunately, the large metal grid coverage ratio electrode would lead to undesirable optical loss. Here, we develop a strategy to balance PEDOT:PSS conductivity and grid optical transmittance via a buried molybdenum oxide/silver grid electrode. In addition, the grid electrode coverage ratio is optimized to reduce its light shading effect. The buried electrode dramatically reduces the device series resistance, which leads to a higher fill factor (FF). With the optimized buried electrode, a record FF of 80% is achieved for flat Si/PEDOT:PSS heterojunction devices. With further enhancement adhesion between the PEDOT:PSS film and Si substrate by a chemical cross-linkable silance, a power conversion efficiency of 16.3% for organic/textured Si heterojunction devices is achieved. Our results provide a path to overcome the inferior organic semiconductor property to enhance the organic/Si heterojunction solar cell.

Medicaid Coverage Expansions and Cigarette Smoking Cessation Among Low-income Adults.

Science.gov (United States)

Koma, Jonathan W; Donohue, Julie M; Barry, Colleen L; Huskamp, Haiden A; Jarlenski, Marian

2017-12-01

Expanding Medicaid coverage to low-income adults may have increased smoking cessation through improved access to evidence-based treatments. Our study sought to determine if states' decisions to expand Medicaid increased recent smoking cessation. Using pooled cross-sectional data from the Behavioral Risk Factor Surveillance Survey for the years 2011-2015, we examined the association between state Medicaid coverage and the probability of recent smoking cessation among low-income adults without dependent children who were current or former smokers (n=36,083). We used difference-in-differences estimation to examine the effects of Medicaid coverage on smoking cessation, comparing low-income adult smokers in states with Medicaid coverage to comparable adults in states without Medicaid coverage, with ages 18-64 years to those ages 65 years and above. Analyses were conducted for the full sample and stratified by sex. Residence in a state with Medicaid coverage among low-income adult smokers ages 18-64 years was associated with an increase in recent smoking cessation of 2.1 percentage points (95% confidence interval, 0.25-3.9). In the comparison group of individuals ages 65 years and above, residence in a state with Medicaid coverage expansion was not associated with a change in recent smoking cessation (-0.1 percentage point, 95% confidence interval, -2.1 to 1.8). Similar increases in smoking cessation among those ages 18-64 years were estimated for females and males (1.9 and 2.2 percentage point, respectively). Findings are consistent with the hypothesis that Medicaid coverage expansions may have increased smoking cessation among low-income adults without dependent children via greater access to preventive health care services, including evidence-based smoking cessation services.

Dispersed metal cluster catalysts by design. Synthesis, characterization, structure, and performance

Energy Technology Data Exchange (ETDEWEB)

Arslan, Ilke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A. [Univ. of Alabama, Tuscaloosa, AL (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States); Katz, Alexander [Univ. of California, Berkeley, CA (United States)

2015-09-30

To understand the class of metal cluster catalysts better and to lay a foundation for the prediction of properties leading to improved catalysts, we have synthesized metal catalysts with well-defined structures and varied the cluster structures and compositions systematically—including the ligands bonded to the metals. These ligands include supports and bulky organics that are being tuned to control both the electron transfer to or from the metal and the accessibility of reactants to influence catalytic properties. We have developed novel syntheses to prepare these well-defined catalysts with atomic-scale control the environment by choice and placement of ligands and applied state-of-the art spectroscopic, microscopic, and computational methods to determine their structures, reactivities, and catalytic properties. The ligands range from nearly flat MgO surfaces to enveloping zeolites to bulky calixarenes to provide controlled coverages of the metal clusters, while also enforcing unprecedented degrees of coordinative unsaturation at the metal site—thereby facilitating bonding and catalysis events at exposed metal atoms. With this wide range of ligand properties and our arsenal of characterization tools, we worked to achieve a deep, fundamental understanding of how to synthesize robust supported and ligand-modified metal clusters with controlled catalytic properties, thereby bridging the gap between active site structure and function in unsupported and supported metal catalysts. We used methods of organometallic and inorganic chemistry combined with surface chemistry for the precise synthesis of metal clusters and nanoparticles, characterizing them at various stages of preparation and under various conditions (including catalytic reaction conditions) and determining their structures and reactivities and how their catalytic properties depend on their compositions and structures. Key characterization methods included IR, NMR, and EXAFS spectroscopies to identify

Fresh organic matter of municipal solid waste enhances phytoextraction of heavy metals from contaminated soil.

Science.gov (United States)

Salati, S; Quadri, G; Tambone, F; Adani, F

2010-05-01

In this study, the ability of the organic fraction of municipal solid wastes (OFMSW) to enhance heavy metal uptake of maize shoots compared with ethylenediamine disuccinic acid (EDDS) was tested on soil contaminated with heavy metals. Soils treated with OFMSW and EDDS significantly increased the concentration of heavy metals in maize shoots (increments of 302%, 66%, 184%, 169%, and 23% for Cr, Cu, Ni, Zn, and Pb with respect to the control and increments of 933%, 482%, 928%, 428%, and 5551% for soils treated with OFMSW and EDDS, respectively). In soil treated with OFMSW, metal uptake was favored because of the high presence of dissolved organic matter (DOM) (41.6x than soil control) that exhibited ligand properties because of the high presence of carboxylic acids. Because of the toxic effect of EDDS on maize plants, soil treated with OFMSW achieved the highest extraction of total heavy metals. Copyright 2009 Elsevier Ltd. All rights reserved.

Electronic coupling effects and charge transfer between organic molecules and metal surfaces

Energy Technology Data Exchange (ETDEWEB)

Forker, Roman

2010-07-01

We employ a variant of optical absorption spectroscopy, namely in situ differential reflectance spectroscopy (DRS), for an analysis of the structure-properties relations of thin epitaxial organic films. Clear correlations between the spectra and the differently intense coupling to the respective substrates are found. While rather broad and almost structureless spectra are obtained for a quaterrylene (QT) monolayer on Au(111), the spectral shape resembles that of isolated molecules when QT is grown on graphite. We even achieve an efficient electronic decoupling from the subjacent Au(111) by inserting an atomically thin organic spacer layer consisting of hexa-peri-hexabenzocoronene (HBC) with a noticeably dissimilar electronic behavior. These observations are further consolidated by a systematic variation of the metal substrate (Au, Ag, and Al), ranging from inert to rather reactive. For this purpose, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is chosen to ensure comparability of the molecular film structures on the different metals, and also because its electronic alignment on various metal surfaces has previously been studied with great intensity. We present evidence for ionized PTCDA at several interfaces and propose the charge transfer to be related to the electronic level alignment governed by interface dipole formation on the respective metals. (orig.)

Possibility of a ferromagnetic and conducting metal-organic network

Science.gov (United States)

Mabrouk, Manel; Hayn, Roland; Denawi, Hassan; Ben Chaabane, Rafik

2018-05-01

In this paper, we present first principles calculations based on the spin-polarized generalized gradient approximation with on-site Coulomb repulsion term (SGGA + U), to explore the electronic and magnetic properties of the novel planar metal-organic networks TM-Pc and TM-TCNB (where TM means a transition metal of the 3d series: Ti, V, Cr, …, or Zn, Pc - Phthalocyanine, and TCNB - Tetracyanobenzene) as free-standing sheets. This work is an extension of two earlier research works dealing with the Mn (Mabrouk et al., 2015) and Fe (Mabrouk et al., 2017) cases. Our theoretical investigations demonstrate that TM-Pc are more stable than TM-TCNB. Our results unveil that all the TM-Pc frameworks have an insulating behavior with the exception of Mn-Pc which is half-metallic and favor antiferromagnetic order in the case of our magnetic systems except for V-Pc which is ferromagnetic. In contrast, the TM-TCNB networks are metallic at least in one spin direction and exhibit long-range ferromagnetic coupling in case for magnetic structures, which represent ideal candidates and an interesting prospect of unprecedented applications in spintronics. In addition, these results may shed light to achieve a new pathway on further experimental research in molecular spintronics.

On-board co2 capture and storage with metal organic framework

KAUST Repository

Eddaoudi, Mohamed; Belmabkhout, Youssef; Shekhah, Osama

2016-01-01

In general, this disclosure describes method of capturing and storing CO2 on a vehicle. The method includes contacting an vehicle exhaust gas with one or more of a first metal organic framework (MOF) composition sufficient to separate CO2 from

Peroxide reduction by a metal-dependent catalase in Nostoc punctiforme (cyanobacteria).

Science.gov (United States)

Hudek, L; Torriero, A A J; Michalczyk, A A; Neilan, B A; Ackland, M L; Bräu, Lambert

2017-05-01

This study investigated the role of a novel metal-dependent catalase (Npun_R4582) that reduces hydrogen peroxide in the cyanobacterium Nostoc punctiforme. Quantitative real-time PCR showed that npun_R4582 relative mRNA levels were upregulated by over 16-fold in cells treated with either 2 μM added Co, 0.5 μM added Cu, 500 μM Mn, 1 μM Ni, or 18 μM Zn. For cells treated with 60 μM H 2 O 2 , no significant alteration in Npun_R4582 relative mRNA levels was detected, while in cells treated with Co, Cu, Mn, Ni, or Zn and 60 μM peroxide, relative mRNA levels were generally above control or peroxide only treated cells. Disruption or overexpression of npun_R4582 altered sensitivity to cells exposed to 60 μM H 2 O 2 and metals for treatments beyond the highest viable concentrations, or in a mixed metal solution for Npun_R4582 - cells. Moreover, overexpression of npun_R4582 increased cellular peroxidase activity in comparison with wild-type and Npun_R4582 - cells, and reduced peroxide levels by over 50%. The addition of cobalt, manganese, nickel, and zinc increased the capacity of Npun_R4582 to reduce the rate or total levels of peroxide produced by cells growing under photooxidative conditions. The work presented confirms the function of NpunR4582 as a catalase and provides insights as to how cells reduce potentially lethal peroxide levels produced by photosynthesis. The findings also show how trace elements play crucial roles as enzymatic cofactors and how the role of Npun_R4582 in hydrogen peroxide breakdown is dependent on the type of metal and the level available to cells.

Creating Hierarchical Pores by Controlled Linker Thermolysis in Multivariate Metal-Organic Frameworks.

Science.gov (United States)

Feng, Liang; Yuan, Shuai; Zhang, Liang-Liang; Tan, Kui; Li, Jia-Luo; Kirchon, Angelo; Liu, Ling-Mei; Zhang, Peng; Han, Yu; Chabal, Yves J; Zhou, Hong-Cai

2018-02-14

Sufficient pore size, appropriate stability, and hierarchical porosity are three prerequisites for open frameworks designed for drug delivery, enzyme immobilization, and catalysis involving large molecules. Herein, we report a powerful and general strategy, linker thermolysis, to construct ultrastable hierarchically porous metal-organic frameworks (HP-MOFs) with tunable pore size distribution. Linker instability, usually an undesirable trait of MOFs, was exploited to create mesopores by generating crystal defects throughout a microporous MOF crystal via thermolysis. The crystallinity and stability of HP-MOFs remain after thermolabile linkers are selectively removed from multivariate metal-organic frameworks (MTV-MOFs) through a decarboxylation process. A domain-based linker spatial distribution was found to be critical for creating hierarchical pores inside MTV-MOFs. Furthermore, linker thermolysis promotes the formation of ultrasmall metal oxide nanoparticles immobilized in an open framework that exhibits high catalytic activity for Lewis acid-catalyzed reactions. Most importantly, this work provides fresh insights into the connection between linker apportionment and vacancy distribution, which may shed light on probing the disordered linker apportionment in multivariate systems, a long-standing challenge in the study of MTV-MOFs.

Distribution of heavy metals in muscles and internal organs of Korean cephalopods and crustaceans: risk assessment for human health.

Science.gov (United States)

Mok, Jong Soo; Kwon, Ji Young; Son, Kwang Tae; Choi, Woo Seok; Shim, Kil Bo; Lee, Tae Seek; Kim, Ji Hoe

2014-12-01

Samples of seven species of cephalopods and crustaceans were collected from major fish markets on the Korean coast and analyzed for mercury (Hg) using a direct Hg analyzer and for the metals cadmium (Cd), lead (Pb), chromium, silver, nickel, copper, and zinc using inductively coupled plasma mass spectrometry. The distributions of heavy metals in muscles, internal organs, and whole tissues were determined, and a risk assessment was conducted to provide information concerning consumer safety. The heavy metals accumulated to higher levels (P octopus (relatively large cephalopods), red snow crab, and snow crab exceeded the European Union limits. The estimated dietary intake of Cd, Pb, and Hg for each part of all species accounted for 1.73 to 130.57%, 0.03 to 0.39%, and 0.93 to 1.67%, respectively, of the provisional tolerable daily intake adopted by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives; the highest values were found in internal organs. The hazard index (HI) is recognized as a reasonable parameter for assessing the risk of heavy metal consumption associated with contaminated food. Because of the high HI (>1.0) of the internal organs of cephalopods and the maximum HI for whole tissue of 0.424, consumers eating internal organs or whole tissues of cephalopods could be at risk of high heavy metal exposure. Therefore, the internal organs of relatively large cephalopods and crabs (except blue crab) are unfit for consumption. However, consumption of flesh after removing internal organs is a suitable approach for decreasing exposure to harmful metals.

Semiconductor Metal-Organic Frameworks: Future Low-Bandgap Materials.

Science.gov (United States)

Usman, Muhammad; Mendiratta, Shruti; Lu, Kuang-Lieh

2017-02-01

Metal-organic frameworks (MOFs) with low density, high porosity, and easy tunability of functionality and structural properties, represent potential candidates for use as semiconductor materials. The rapid development of the semiconductor industry and the continuous miniaturization of feature sizes of integrated circuits toward the nanometer (nm) scale require novel semiconductor materials instead of traditional materials like silicon, germanium, and gallium arsenide etc. MOFs with advantageous properties of both the inorganic and the organic components promise to serve as the next generation of semiconductor materials for the microelectronics industry with the potential to be extremely stable, cheap, and mechanically flexible. Here, a perspective of recent research is provided, regarding the semiconducting properties of MOFs, bandgap studies, and their potential in microelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of a metallic front gate on the temperature-dependent electronic property of pentacene films

Energy Technology Data Exchange (ETDEWEB)

Lin, Yow-Jon, E-mail: rzr2390@yahoo.com.tw [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China); Tsao, Hou-Yen [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China); Liu, Day-Shan [Graduate Institute of Electro-Optical and Materials Science, National Formosa University, Huwei 632, Taiwan (China)

2014-11-14

The effect of a metallic front gate on the temperature-dependent electronic property of pentacene films was investigated in this study. The carrier mobility exhibits strong temperature dependence, implying the dominance of tunneling (hopping) at low (high) temperatures. The room-temperature mobility was drastically increased by capping an In (Au) layer on the pentacene front surface. However, the carrier concentration is not affected. An increase in the phonon energy occurs for In-capped or Au-capped pentacene samples, which corresponds to the abrupt transition to the nonlocal electron–phonon coupling. The enhanced mobility by capping a metal layer is attributed to a change in the electron–phonon coupling. - Highlights: • For the metal-capped and uncapped pentacene films, the mobility was researched. • The mobility was dramatically increased by capping an In (Au) layer. • The induced strain by capping a metal layer is found. • The strain may lead to the electron–phonon coupling variation. • The enhanced mobility is attributed to the weakened electron–phonon coupling.

Interface properties of Fe/MgO/Cu-phthalocyanine metal-insulator-organic semiconductor structures

International Nuclear Information System (INIS)

Lee, Nyunjong; Bae, Yujeong; Kim, Taehee; Ito, Eisuke; Hara, Masahiko

2014-01-01

Hybrid interface structures consisting of organic copper-phthalocyanine (CuPc) and ferromagnetic metal Fe(001) with and without a MgO(001) cover were investigated by using surface sensitive techniques of X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy. A systematic study of the energy level alignment at the interfaces was carried out. For the hybrid interfaces considered here, our results indicate that the insertion of an artificially-grown ultra-thin oxide layer MgO(001) can prevent Femi level pinning and induce a rather large interface dipole, thereby resulting in remarkable CuPc Fermi level shifts when the thickness of the CuPc film is less than 3 nm. This study provides a better understanding of spin filtering in MgO-based organic spin devices and a new way to alter the interface electronic structure of metal/organic semiconductor hybrid systems.

Effects of heavy metals (other than mercury) on marine and estuarine organisms

Energy Technology Data Exchange (ETDEWEB)

Bryan, G W

1971-01-01

Heavy metals such as copper, zinc and lead are normal constituents of marine and estuarine environments. When additional quantities are introduced from industrial wastes or sewage they enter the biogeochemical cycle and, as a result of being potentially toxic, may interfere with the ecology of a particular environment. In different marine organisms, the behavior of heavy metals is described in terms of their absorption, storage, excretion and regulation when different concentrations are available in the environment. At higher concentrations, the detrimental effects of heavy metals become apparent and their different toxic effects and factors affecting them are also described. 78 references, 9 figures, 4 tables.

Catoptric electrodes: transparent metal electrodes using shaped surfaces.

Science.gov (United States)

Kik, Pieter G

2014-09-01

An optical electrode design is presented that theoretically allows 100% optical transmission through an interdigitated metallic electrode at 50% metal areal coverage. This is achieved by redirection of light incident on embedded metal electrode lines to an angle beyond that required for total internal reflection. Full-field electromagnetic simulations using realistic material parameters demonstrate 84% frequency-averaged transmission for unpolarized illumination across the entire visible spectral range using a silver interdigitated electrode at 50% areal coverage. The redirection is achieved through specular reflection, making it nonresonant and arbitrarily broadband, provided the electrode width exceeds the optical wavelength. These findings could significantly improve the performance of photovoltaic devices and optical detectors that require high-conductivity top contacts.

Metal-Organic Frameworks: Building Block Design Strategies for the Synthesis of MOFs.

KAUST Repository

Luebke, Ryan

2014-01-01

A significant and ongoing challenge in materials chemistry and furthermore solid state chemistry is to design materials with the desired properties and characteristics. The field of Metal-Organic Frameworks (MOFs) offers several strategies

Accumulation of different metals in apple trees organs from an unfertilized orchard

International Nuclear Information System (INIS)

Stanica, F.

1999-01-01

Working in an unfertilized apple orchard, planted on brown-reddish soil in Baneasa - Bucuresti, the accumulation of different metals in trees organs was studied: leaves, vegetative branches, fruit branches and fruits. The samples were taken from 'Golden delicious' variety, planted at 10 meters, 'Idared' variety, planted at 100 meters and 'Akane' variety, planted at 200 meters from the Bucuresti-Ploiesti motorway. Lead accumulation depended on the distance to the pollution source and organ type. In leaves, lead was found even at 100 m from the road border (11.7 ppm in 'Idared' variety). At 10 m the leaves content was much higher (306 ppm, 'Golden delicious'). Because of the specific metabolism selectivity apple trees didn't accumulate lead into fruit branches and fruits. Copper leaves content varied between 5.85 ppm ('Golden delicious') and 16.2 ppm ('Akane') being lower than the fruits content (8.36 ppm 'Idared' - 23.0 ppm 'Golden delicious'). In apple tree fruit branches the Cu accumulation was 2-3 times higher than in the vegetative branches. The same fruit branches accumulated the highest quantity of zinc (between 67.5 and 83.9 ppm). Fruit contents in zinc (10.0-16.9 ppm) were close to the normal value: 15 ppm, but leave contents (43.3-48.7 ppm) were more than doubled compared to the normal range: 15-20 ppm. The 'Idared' variety accumulated the lowest quantity of nickel in all analyzed organs. Iron accumulation was different in function of the analyzed organ, variety and ion type (Fe 2+ , Fe 3+ ). The highest Fe 3+ content was found in 'Golden delicious' leaves: 547 ppm and the highest Fe 2+ content in 'Idared' leaves: 96.0 ppm. The lowest iron content was found in fruits. The manganese content of the analyzed organs varied from 8.32 to 130 ppm. Refs. 4 (author)

Electrochemistry and electrochemiluminescence from a redox-active metal-organic framework.

Science.gov (United States)

Xu, Yang; Yin, Xue-Bo; He, Xi-Wen; Zhang, Yu-Kui

2015-06-15

The marriage of metal-organic frameworks (MOFs) and electrochemiluminescence (ECL) can combine their merits together. Designing ECL-active MOF with a high electron transfer capacity and high stability is critical for ECL emission. Here we reported the ECL from a redox-active MOF prepared from {Ru[4,4'-(HO2C)2-bpy]2bpy}(2+) and Zn(2+); a property of MOFs has not been reported previously. The MOF structure is independent of its charge and is therefore stable electrochemically. The redox-activity and well-ordered porous structure of the MOF were confirmed by its electrochemical properties and ECL emission. The high ECL emission indicated the ease of electron transfer between the MOF and co-reactants. Furthermore, the MOF exhibited permselectivity, charge selectivity, and catalytic selectivity along with a stable and concentration-dependent ECL emission toward co-reactants. ECL mechanism was proposed based on the results. The detection and recovery of cocaine in the serum sample was used to validate the feasibility of MOF- based ECL system. The information obtained in this study provides a better understanding of the redox properties of MOFs and their potential electrochemical applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Conduction mechanism in assemblies of metal nanoparticles linked by organic molecules

International Nuclear Information System (INIS)

Mueller, K.-H.; Herrmann, J.; Raguse, B.; Baxter, G.; Reda, T.

2002-01-01

Full text: We have investigated theoretically and experimentally electron transport through thin films of gold nanoparticles which are linked by alkanedithiol molecules of different chain lengths. We find that conduction between neighbouring nanoparticles takes place by electron tunnelling along weakly conducting organic linker molecules. Using a tight binding model for the alkanedithiol molecules to describe the tunnelling process we predict the conductivity to decrease exponentially with the length of the molecules. During tunnelling the electron has to overcome a charging energy due to the electron-hole interaction between tunnelling electrons and the corresponding holes left behind on the donor nanoparticle. Experimentally we find that large applied voltages cause nonlinear I-V characteristics and that the temperature dependence of the conductivity does not show Arrhenius behaviour but instead is of the form exp[-(E o /kT) 1/2 ]. Using percolation theory for a network of metal nanoparticles separated by barriers we show that strong disorder caused by variations in nanoparticle size and linker length as well as randomly trapped electric charges on the linker molecules can well explain our experimental data

Metal-organic frameworks for the removal of toxic industrial chemicals and chemical warfare agents.

Science.gov (United States)

Bobbitt, N Scott; Mendonca, Matthew L; Howarth, Ashlee J; Islamoglu, Timur; Hupp, Joseph T; Farha, Omar K; Snurr, Randall Q

2017-06-06

Owing to the vast diversity of linkers, nodes, and topologies, metal-organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH 3 , SO 2 , NO 2 , H 2 S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal-organic frameworks.

The influence of soil organic carbon on interactions between microbial parameters and metal concentrations at a long-term contaminated site

Energy Technology Data Exchange (ETDEWEB)

Muhlbachova, G. [Crop Research Institute, Drnovska 507, 161 06 Prague 6, Ruzyne (Czech Republic); Sagova-Mareckova, M., E-mail: sagova@vurv.cz [Crop Research Institute, Drnovska 507, 161 06 Prague 6, Ruzyne (Czech Republic); Omelka, M. [Charles University, Faculty of Mathematics and Physics, Dept. of Probability and Mathematical Statistics, Prague 8, Karlin (Czech Republic); Szakova, J.; Tlustos, P. [Czech University of Life Sciences, Department of Agroenvironmental Chemistry and Plant Nutrition, Prague 6, Suchdol (Czech Republic)

2015-01-01

The effects of lead, zinc, cadmium, arsenic and copper deposits on soil microbial parameters were investigated at a site exposed to contamination for over 200 years. Soil samples were collected in triplicates at 121 sites differing in contamination and soil organic carbon (SOC). Microbial biomass, respiration, dehydrogenase activity and metabolic quotient were determined and correlated with total and extractable metal concentrations in soil. The goal was to analyze complex interactions between toxic metals and microbial parameters by assessing the effect of soil organic carbon in the relationships. The effect of SOC was significant in all interactions and changed the correlations between microbial parameters and metal fractions from negative to positive. In some cases, the effect of SOC was combined with that of clay and soil pH. In the final analysis, dehydrogenase activity was negatively correlated to total metal concentrations and acetic acid extractable metals, respiration and metabolic quotient were to ammonium nitrate extractable metals. Dehydrogenase activity was the most sensitive microbial parameter correlating most frequently with contamination. Total and extractable zinc was most often correlated with microbial parameters. The large data set enabled robust explanation of discrepancies in organic matter functioning occurring frequently in analyzing of contaminated soil processes. - Highlights: • Soil organic carbon affected all interactions between metals and microorganisms. • Soil organic carbon adjustment changed correlations from positive to negative. • Ammonium nitrate extractable metals were the most influencing fraction. • Dehydrogenase activity was the most affected soil parameter. • Zinc was the most toxic metal among studied metals.

The influence of soil organic carbon on interactions between microbial parameters and metal concentrations at a long-term contaminated site

International Nuclear Information System (INIS)

Muhlbachova, G.; Sagova-Mareckova, M.; Omelka, M.; Szakova, J.; Tlustos, P.

2015-01-01

The effects of lead, zinc, cadmium, arsenic and copper deposits on soil microbial parameters were investigated at a site exposed to contamination for over 200 years. Soil samples were collected in triplicates at 121 sites differing in contamination and soil organic carbon (SOC). Microbial biomass, respiration, dehydrogenase activity and metabolic quotient were determined and correlated with total and extractable metal concentrations in soil. The goal was to analyze complex interactions between toxic metals and microbial parameters by assessing the effect of soil organic carbon in the relationships. The effect of SOC was significant in all interactions and changed the correlations between microbial parameters and metal fractions from negative to positive. In some cases, the effect of SOC was combined with that of clay and soil pH. In the final analysis, dehydrogenase activity was negatively correlated to total metal concentrations and acetic acid extractable metals, respiration and metabolic quotient were to ammonium nitrate extractable metals. Dehydrogenase activity was the most sensitive microbial parameter correlating most frequently with contamination. Total and extractable zinc was most often correlated with microbial parameters. The large data set enabled robust explanation of discrepancies in organic matter functioning occurring frequently in analyzing of contaminated soil processes. - Highlights: • Soil organic carbon affected all interactions between metals and microorganisms. • Soil organic carbon adjustment changed correlations from positive to negative. • Ammonium nitrate extractable metals were the most influencing fraction. • Dehydrogenase activity was the most affected soil parameter. • Zinc was the most toxic metal among studied metals

Structural Design Principle of Small-Molecule Organic Semiconductors for Metal-Free, Visible-Light-Promoted Photocatalysis.

Science.gov (United States)

Wang, Lei; Huang, Wei; Li, Run; Gehrig, Dominik; Blom, Paul W M; Landfester, Katharina; Zhang, Kai A I

2016-08-08

Herein, we report on the structural design principle of small-molecule organic semiconductors as metal-free, pure organic and visible light-active photocatalysts. Two series of electron-donor and acceptor-type organic semiconductor molecules were synthesized to meet crucial requirements, such as 1) absorption range in the visible region, 2) sufficient photoredox potential, and 3) long lifetime of photogenerated excitons. The photocatalytic activity was demonstrated in the intermolecular C-H functionalization of electron-rich heteroaromates with malonate derivatives. A mechanistic study of the light-induced electron transport between the organic photocatalyst, substrate, and the sacrificial agent are described. With their tunable absorption range and defined energy-band structure, the small-molecule organic semiconductors could offer a new class of metal-free and visible light-active photocatalysts for chemical reactions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Medicare Coverage Database

Data.gov (United States)

U.S. Department of Health & Human Services — The Medicare Coverage Database (MCD) contains all National Coverage Determinations (NCDs) and Local Coverage Determinations (LCDs), local articles, and proposed NCD...

Poisoning of domestic animals with heavy metals

Directory of Open Access Journals (Sweden)

Velev Romel

2009-01-01

Full Text Available The term heavy metal refers to a metal that has a relatively high density and is toxic for animal and human organism at low concentrations. Heavy metals are natural components of the Earth's crust. They cannot be degraded or destroyed. To a small extent they enter animal organism via food, drinking water and air. Some heavy metals (e.g cooper, iron, chromium, zinc are essential in very low concentrations for the survival of all forms of life. These are described as essential trace elements. However, when they are present in greater quantities, like the heavy metals lead, cadmium and mercury which are already toxic in very low concentrations, they can cause metabolic anomalies or poisoning. Heavy metal poisoning of domestic animals could result, for instance, from drinking-water contamination, high ambient air concentrations near emission sources, or intake via the food chain. Heavy metals are dangerous because they tend to bioaccumulate in a biological organism over time. Manifestation of toxicity of individual heavy metals varies considerably, depending on dose and time of exposure, species, gender and environmental and nutritional factors. Large differences exist between the effects of a single exposure to a high concentration, and chronic exposures to lower doses. The aim of this work is to present the source of poisoning and toxicity of some heavy metals (lead, mercury, cadmium, thallium, arsenic, as well as new data about effects of those heavy metals on the health of domestic animals. .

Metal-Organic Framework of Lanthanoid Dinuclear Clusters Undergoes Slow Magnetic Relaxation

Directory of Open Access Journals (Sweden)

Hikaru Iwami

2017-01-01

Full Text Available Lanthanoid metal-organic frameworks (Ln-MOFs can adopt a variety of new structures due to the large coordination numbers of Ln metal ions, and Ln-MOFs are expected to show new luminescence and magnetic properties due to the localized f electrons. In particular, some Ln metal ions, such as Dy(III and Tb(III ions, work as isolated quantum magnets when they have magnetic anisotropy. In this work, using 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid (H3TATB as a ligand, two new Ln-MOFs, [Dy(TATB(DMF2] (1 and [Tb(TATB(DMF2] (2, were obtained. The Ln-MOFs contain Ln dinuclear clusters as secondary building units, and 1 underwent slow magnetic relaxation similar to single-molecule magnets.

Block Copolymer-Templated Approach to Nanopatterned Metal-Organic Framework Films.

Science.gov (United States)

Zhou, Meimei; Wu, Yi-Nan; Wu, Baozhen; Yin, Xianpeng; Gao, Ning; Li, Fengting; Li, Guangtao

2017-08-17

The fabrication of patterned metal-organic framework (MOF) films with precisely controlled nanoscale resolution has been a fundamental challenge in nanoscience and nanotechnology. In this study, nanopatterned MOF films were fabricated using a layer-by-layer (LBL) growth method on functional templates (such as a bicontinuous nanoporous membrane or a structure with highly long-range-ordered nanoscopic channels parallel to the underlying substrate) generated by the microphase separation of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymers. HKUST-1 can be directly deposited on the templates without any chemical modification because the pyridine groups in P2VP interact with metal ions via metal-BCP complexes. As a result, nanopatterned HKUST-1 films with feature sizes below 50 nm and controllable thicknesses can be fabricated by controlling the number of LBL growth cycles. The proposed fabrication method further extends the applications of MOFs in various fields. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heavy metal and Pb isotopic compositions of aquatic organisms in the Pearl River Estuary, South China

International Nuclear Information System (INIS)

Ip, C.C.M.; Li, X.D.; Zhang, G.; Wong, C.S.C.; Zhang, W.L.

2005-01-01

The accumulation of trace metals in aquatic organisms may lead to serious health problems through the food chain. The present research project aims to study the accumulation and potential sources of trace metals in aquatic organisms of the Pearl River Estuary (PRE). Four groups of aquatic organisms, including fish, crab, shrimp, and shellfish, were collected in the PRE for trace metal and Pb isotopic analyses. The trace metal concentrations in the aquatic organism samples ranged from 0.01 to 2.10 mg/kg Cd, 0.02 to 4.33 mg/kg Co, 0.08 to 4.27 mg/kg Cr, 0.15 to 77.8 mg/kg Cu, 0.17 to 31.0 mg/kg Ni, 0.04 to 30.7 mg/kg Pb, and 8.78 to 86.3 mg/kg Zn (wet weight). High concentrations of Cd were found in crab, shrimp and shellfish samples, while high concentration of Pb was found in fish. In comparison with the baseline reference values in other parts of the world, fish in the PRE had the highest elevated trace metals. The results of Pb isotopic compositions indicated that the bioaccumulation of Pb in fish come from a wide variety of food sources and/or exposure pathways, particularly the anthropogenic inputs. - Relative high concentrations of Cd were found in crab, shrimp and shellfish samples while high concentration of Pb was found in fish, particularly from the anthropogenic inputs

Complexation with dissolved organic matter and solubility control of heavy metals in sandy soil

NARCIS (Netherlands)

Weng, L.; Temminghoff, E.J.M.; Lofts, S.; Tipping, E.; Riemsdijk, van W.H.

2002-01-01

The complexation of heavy metals with dissolved organic matter (DOM) in the environment influences the solubility and mobility of these metals. In this paper, we measured the complexation of Cu, Cd, Zn, Ni, and Pb with DOM in the soil solution at pH 3.7-6.1 using a Donnan membrane technique. The

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.

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

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)

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

Science.gov (United States)

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

2015-01-01

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

Organic pollutants and heavy metals in rainwater runoff and their fate in the unsaturated soil zone. Final report

International Nuclear Information System (INIS)

Grotehusmann, D.; Rohlfing, R.; Weyer, G.; Dittrich, D.; Gowik, P.; Pernak, P.

1991-01-01

This bibliographic study is part of the BMFT intergrated project ''Possibilitiis and limits of [ drainage in consederation of the soil and groundwater protection''. Subjects: Environmental relevance and general distribution of organic pollutants; organic pollutants in rain water, soil, and groundwater; fate of organic pollutants in soil; environmental relevance of heavy metals in soil, rain water, and runof; fate of heavy metals in the unsaturated soil rare. (orig./BBR) [de

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