WorldWideScience

Sample records for biological metal cations

  1. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl-, NO3-, C2O42-) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author)

  2. Understanding the bioavailability and sequestration of different metal cations in the presence of a biodegradable chelant S,S-EDDS in biological fluids and natural waters.

    Science.gov (United States)

    Bretti, Clemente; Cigala, Rosalia Maria; De Stefano, Concetta; Lando, Gabriele; Sammartano, Silvio

    2016-05-01

    Ethylenediamine-N,N'-disuccinic acid is a biodegradable alternative to EDTA, therefore its use for the sequestration of Ca(2+), Sn(2+), Cu(2+), Zn(2+) and Fe(3+) is analyzed. New data on its binding ability towards these cations were obtained with potentiometric, voltammetric and calorimetric measurements at different ionic strengths and at T = 298.15 K. Real multi-component fluids, namely fresh water, urine, sea water, saliva and blood plasma were chosen as case studies to evaluate the sequestering ability of EDDS in comparison with EDTA. Speciation diagrams were drawn in selected conditions, considering all interactions among the "natural" components of the fluid and those studied in this work, EDDS and EDTA (cL = 1 mmol dm(-3)) as sequestering agents and the cited metal cations (cM ∼ 10(-5) mol dm(-3)). The comparison of the sequestering ability of EDDS and EDTA is done using pM and pL0.5. In blood plasma the plasma mobilizing index was adopted. It was found that EDDS is a good alternative to EDTA, which tends to bind Ca(2+) and Mg(2+) more than EDDS. In particular, EDTA cannot be used as a sequestrant for Sn(2+) when cCa > cEDTA. EDDS is more efficient than EDTA at pH PMI of EDDS towards Cu(2+) is higher than that of EDTA. Thermodynamic information, in terms of ΔH and ΔS, for the protonation and metal complex formation reactions are reported. PMID:26921587

  3. Understanding the bioavailability and sequestration of different metal cations in the presence of a biodegradable chelant S,S-EDDS in biological fluids and natural waters.

    Science.gov (United States)

    Bretti, Clemente; Cigala, Rosalia Maria; De Stefano, Concetta; Lando, Gabriele; Sammartano, Silvio

    2016-05-01

    Ethylenediamine-N,N'-disuccinic acid is a biodegradable alternative to EDTA, therefore its use for the sequestration of Ca(2+), Sn(2+), Cu(2+), Zn(2+) and Fe(3+) is analyzed. New data on its binding ability towards these cations were obtained with potentiometric, voltammetric and calorimetric measurements at different ionic strengths and at T = 298.15 K. Real multi-component fluids, namely fresh water, urine, sea water, saliva and blood plasma were chosen as case studies to evaluate the sequestering ability of EDDS in comparison with EDTA. Speciation diagrams were drawn in selected conditions, considering all interactions among the "natural" components of the fluid and those studied in this work, EDDS and EDTA (cL = 1 mmol dm(-3)) as sequestering agents and the cited metal cations (cM ∼ 10(-5) mol dm(-3)). The comparison of the sequestering ability of EDDS and EDTA is done using pM and pL0.5. In blood plasma the plasma mobilizing index was adopted. It was found that EDDS is a good alternative to EDTA, which tends to bind Ca(2+) and Mg(2+) more than EDDS. In particular, EDTA cannot be used as a sequestrant for Sn(2+) when cCa > cEDTA. EDDS is more efficient than EDTA at pH < 8, particularly in urine, where carbonate is absent. In sea water, the sequestering ability of EDDS towards Fe(3+) is higher than that of EDTA. In blood plasma, the PMI of EDDS towards Cu(2+) is higher than that of EDTA. Thermodynamic information, in terms of ΔH and ΔS, for the protonation and metal complex formation reactions are reported.

  4. Spectroscopy and interactions of metal and metal cation complexes

    OpenAIRE

    Plowright, Richard J.

    2010-01-01

    The work in this thesis looks at the spectroscopy and interactions of metals and metal cation complexes. There are two aspects of this vast subject that are considered: the electronic spectroscopy of Au-RG complexes and the ion-molecule chemistry of metals important in the mesosphere-lower thermosphere (MLT) region of the atmosphere. The spectroscopy of the molecular states in the vicinity of the strong Au 2P3/2, 1/2 ← 2S1/2 atomic transition, have been studied for the Au-RG (RG = Ne, Ar...

  5. Effects of metallic cations in the beryl flotation

    International Nuclear Information System (INIS)

    The beryl zeta potential in microelectrophoretic cell is studied in the presence of neutral electrolyte, cations of calcium, magnesium and iron. The petroleum sulfonate is used how collector in Hallimond tube. Hydroxy complex of metallic cations seems activate the ore and precipitates of colloidal metallic hidroxies seems lower him when added to the mixture. (M.A.C.)

  6. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    Science.gov (United States)

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  7. Cation Selectivity in Biological Cation Channels Using Experimental Structural Information and Statistical Mechanical Simulation.

    Directory of Open Access Journals (Sweden)

    Justin John Finnerty

    Full Text Available Cation selective channels constitute the gate for ion currents through the cell membrane. Here we present an improved statistical mechanical model based on atomistic structural information, cation hydration state and without tuned parameters that reproduces the selectivity of biological Na+ and Ca2+ ion channels. The importance of the inclusion of step-wise cation hydration in these results confirms the essential role partial dehydration plays in the bacterial Na+ channels. The model, proven reliable against experimental data, could be straightforwardly used for designing Na+ and Ca2+ selective nanopores.

  8. Metal Cations in G-Quadruplex Folding and Stability

    Science.gov (United States)

    Bhattacharyya, Debmalya; Mirihana Arachchilage, Gayan; Basu, Soumitra

    2016-09-01

    This review is focused on the structural and physico-chemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-Quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures. The nature, location and dynamics of the cation coordination and their impact on the overall GQ stability are dependent on several factors such as the ionic radii, hydration energy and the bonding strength to the O6 of guanines. The intracellular monovalent cation concentration and the localized ion concentrations determine the formation of GQs and can potentially dictate their regulatory roles. A wide range of biochemical and biophysical studies on an array of GQ enabling sequences have generated at a minimum the knowledge base that allows us to often predict the stability of GQs in presence of the physiologically relevant metal ions, however, prediction of conformation of such GQs is still out of the realm.

  9. Metal Cations in G-Quadruplex Folding and Stability

    Science.gov (United States)

    Bhattacharyya, Debmalya; Mirihana Arachchilage, Gayan; Basu, Soumitra

    2016-01-01

    This review is focused on the structural and physicochemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures. The nature, location, and dynamics of the cation coordination and their impact on the overall GQ stability are dependent on several factors such as the ionic radii, hydration energy, and the bonding strength to the O6 of guanines. The intracellular monovalent cation concentration and the localized ion concentrations determine the formation of GQs and can potentially dictate their regulatory roles. A wide range of biochemical and biophysical studies on an array of GQ enabling sequences have generated at a minimum the knowledge base that allows us to often predict the stability of GQs in the presence of the physiologically relevant metal ions, however, prediction of conformation of such GQs is still out of the realm. PMID:27668212

  10. The role of alkali metal cations in the stabilization of guanine quadruplexes: why K(+) is the best.

    Science.gov (United States)

    Zaccaria, F; Paragi, G; Fonseca Guerra, C

    2016-08-21

    The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkali metal cation is needed to assist self-assembly. Our quantum chemical computations on these supramolecular systems are able to reproduce the experimental order of affinity of the guanine quadruplexes for the cations Li(+), Na(+), K(+), Rb(+), and Cs(+). The strongest binding is computed between the potassium cation and the quadruplex as it occurs in nature. The desolvation and the size of alkali metal cations are thought to be responsible for the order of affinity. Until now, the relative importance of these two factors has remained unclear and debated. By assessing the quantum chemical 'size' of the cation, determining the amount of deformation of the quadruplex needed to accommodate the cation and through the energy decomposition analysis (EDA) of the interaction energy between the cation and the guanines, we reveal that the desolvation and size of the alkali metal cation are both almost equally responsible for the order of affinity. PMID:27185388

  11. Dilution thermodynamics of the biologically relevant cation mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Kaczyński, Marek, E-mail: marek.kaczynski@pwr.wroc.pl; Borowik, Tomasz, E-mail: office@novel-id.pl; Przybyło, Magda, E-mail: magdalena.przybylo@pwr.wroc.pl; Langner, Marek, E-mail: marek.langner@pwr.wroc.pl

    2014-01-10

    Graphical abstract: - Highlights: • Dilution energetics of Ca{sup 2+} can be altered by the aqueous phase ionic composition. • Dissipated heat upon Ca{sup 2+} dilution is drastically reduced in the K{sup +} presence. • Reduction of the enthalpy change upon Ca{sup 2+} dilution is K{sup +} concentration dependent. • The cooperativity of Ca{sup 2+} hydration might be of great biological relevance providing a thermodynamic argument for the specific ionic composition of the intracellular environment. - Abstract: The ionic composition of intracellular space is rigorously controlled by a variety of processes consuming large quantities of energy. Since the energetic efficiency is an important evolutional criterion, therefore the ion fluxes within the cell should be optimized with respect to the accompanying energy consumption. In the paper we present the experimental evidence that the dilution enthalpies of the biologically relevant ions; i.e. calcium and magnesium depend on the presence of monovalent cations; i.e. sodium and potassium. The heat flow generated during the dilution of ionic mixtures was measured with the isothermal titration calorimetry. When calcium was diluted together with potassium the dilution enthalpy was drastically reduced as the function of the potassium concentration present in the solution. No such effect was observed when the potassium ions were substituted with sodium ones. When the dilution of magnesium was investigated the dependence of the dilution enthalpy on the accompanying monovalent cation was much weaker. In order to interpret experimental evidences the ionic cluster formation is postulated. The specific organization of such cluster should depend on ions charges, sizes and organization of the hydration layers.

  12. Molecular modeling of organic corrosion inhibitors: why bare metal cations are not appropriate models of oxidized metal surfaces and solvated metal cations.

    Science.gov (United States)

    Kokalj, Anton

    2014-01-01

    The applicability of various models of oxidized metal surfaces - bare metal cations, clusters of various size, and extended (periodic) slabs - that are used in the field of quantum-chemical modeling of corrosion inhibitors is examined and discussed. As representative model systems imidazole inhibitor, MgO surface, and solvated Mg(2+) ion are considered by means of density-functional-theory calculations. Although the results of cluster models are prone to cluster size and shape effects, the clusters of moderate size seem useful at least for qualitative purposes. In contrast, the bare metal cations are useless not only as models of oxidized surfaces but also as models of solvated cations, because they bind molecules several times stronger than the more appropriate models. In particular, bare Mg(2+) binds imidazole by 5.9 eV, while the slab model of MgO(001) by only 0.35 eV. Such binding is even stronger for 3+ cations, e.g., bare Al(3+) binds imidazole by 17.9 eV. The reasons for these fantastically strong binding energies are discussed and it is shown that the strong bonding is predominantly due to electron charge transfer from molecule to metal cation, which stems from differences between molecular and metal ionization potentials.

  13. Dipicolinate complexes of main group metals with hydrazinium cation

    Indian Academy of Sciences (India)

    K Saravanan; S Govindarajan

    2002-02-01

    Some new coordination complexes of hydrazinium main group metal dipicolinate hydrates of formulae (N2H5)2M(dip)2.H2O (where, M =Ca, Sr, Ba or Pb and = 0, 2, 4 and 3 respectively and dip = dipicolinate), N2H5Bi(dip)2.3H2O and (N2H5)3Bi(dip)3.4H2O have been prepared and characterized by physico-chemical techniques. The infrared spectra of the complexes reveal the presence of tridentate dipicolinate dianions and non-coordinating hydrazinium cations. Conductance measurements show that the mono, di and trihydrazinium complexes behave as 1:1, 2:1 and 3:1 electrolytes respectively, in aqueous solution. Thermal decomposition studies show that these compounds lose water followed by endothermic decomposition of hydrazine to give respective metal hydrogendipicolinate intermediates, which further decompose exothermically to the final product of either metal carbonates (Ca, Sr, Ba and Pb) or metal oxycarbonates (Bi). The coordination numbers around the metal ions differ from compound to compound. The various coordination numbers exhibited by these metals are six (Ca), seven (Ba), eight (Sr) and nine (Pb and Bi). In all the complexes the above coordination number is attained by tridentate dipicolinate dianions and water molecules. The X-ray diffraction patterns of these compounds differ from one another suggesting that they are not isomorphous.

  14. Effect of heavy metal cations on the activity of cathepsin D (in vitro study) Effect of heavy metal cations on the activity of cathepsin D (in vitro study)

    OpenAIRE

    Alicja Karwowska; Radosław Łapiński; Marek Gacko; Ewa Grzegorczyk; Joanna Żurawska; Jan K. Karczewski

    2012-01-01

    We studied the effect of heavy metal cations: Fe 2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ on the activity of
    cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin
    was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg2+ cations
    inhibit the activity of cathepsin D. Cations Hg2+ damage lysosomes and release cathepsin D from these organelles.We studied the effect of heavy metal c...

  15. Metal cations inserted in vanadium-oxide nanotubes

    International Nuclear Information System (INIS)

    Vanadium-oxide nanotubes (VO x-NTs) consist of nanosize cylinders of thin, easily bent vanadyl (VO x) wall chains, which are open at both ends. Surfactant molecules (e.g. C12H27N) can be easily trapped in the interior of the nanotube walls. The structure of as-synthesized VO x-NTs are observed to collapse to an amorphous vanadium oxide at temperatures greater than 250 deg, C. This happens, even under a protective atmosphere. This property makes the VO x-NTs unusable as a catalyst at temperatures between 400-500 deg, C, which is the temperature range where many applications would exist. In order to increase the thermal stability of VO x-NTs several exchange reactions have been used to modify the original nanotubes. In these reactions metallic cations (Cd2+, Co2+, Mn2+ or Zn2+) were introduced. It was observed that that the morphology of the nanotubes remained unchanged after the exchange reactions were performed. In order to characterize the exchanged VO x-NTs the following analytic techniques were used: scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared, particle-induced X-ray emission and Rutherford backscattering spectrometry. The results showed that the VO x-NTs exchanged with metallic cations have preserved their tubular morphology. However, it has not been possible to fully perform a 100% efficient exchange reaction

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

    OpenAIRE

    MAJA RADETIC; DARINKA RADOJEVIC; VESNA ILIC; DRAGAN JOCIC; DRAGAN POVRENOVIC; BRANISLAV POTKONJAK; NEVENA PUAC; PETAR JOVANCIC

    2007-01-01

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

  17. An Overview on Metal Cations Extraction by Azocalixarenes

    Directory of Open Access Journals (Sweden)

    Hasalettin Deligöz

    2011-12-01

    Full Text Available In this overview, our main aim is to present the design, preparation, characterization, and extraction/sorption properties of chromogenic azocalix[4]arenes (substituted with different groups toward metal cations. Azocalixarenes, which contain a conjugated chromophore, i.e. azo (-N=N- group are synthesized in “one-pot” procedures in satisfactory yields. A wide variety of applications is expected by the functionalization of the side arms. Some of them are used to complex with metal ions. These macrocycles due to their bowl-shaped geometry are indeed used as hosts allowing ionic or organic guests to coordinate onto their cavity. The azocalixarene based ionophores are generally applied in various fields such as catalyst recovery, power plant, agriculture, metals finishing, microelectonics, biotechnology processes, rare earths speciation, and potable water purification. Besides these, they find applications in the area of selective ion extractions, receptors, optical devices, chemical sensor devices, the stationary phase for capillary chromatography, ion transport membranes, and luminescence probes etc. This survey is focused to provide overview an of the versatile nature of azocalix[n]arenes as highly efficient extractants for metal ions treated as pollutants.

  18. Ab initio study of the transition-metal carbene cations

    Institute of Scientific and Technical Information of China (English)

    李吉海; 冯大诚; 冯圣玉

    1999-01-01

    The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH2+ were investigated by ab initio molecular orbital theory (HF/LANL2DZ). All of MCH2+ are coplanar. In the closed shell structures the C bonds to M with double bonds; while in the open shell structures the partial double bonds are formed, because one of the σ and π orbitals is singly occupied. It is mainly the π-type overlap between the 2px orbital of C and 4px, 3dxz, orbitals of M+ that forms the π orbitals. The dissociation energies of C—M bond appear in periodic trend from Sc to Cu. Most of the calculated bond dissociation energies are close to the experimental ones.

  19. Tryptophan fluorescence quenching by alkaline earth metal cations in deionized bacteriorhodopsin.

    Science.gov (United States)

    Wang, G; Wang, A J; Hu, K S

    2000-12-01

    Tryptophan quenching by the addition of alkaline earth metal cations to deionized bacteriorhodopsin suspensions was determined. The results show that the addition of cation primarily quenches fluorescence from surface tryptophan residues. The quenched intensity exhibits a 1/R dependence, where R is the ionic radius of the corresponding metal ion. This observation results from a stronger energy transfer coupling between the tryptophan and the retinal. The membrane curvature may be involved as a result of cations motion and correlated conformational changes. PMID:11332888

  20. Effect of heavy metal cations on the activity of cathepsin D (in vitro study Effect of heavy metal cations on the activity of cathepsin D (in vitro study

    Directory of Open Access Journals (Sweden)

    Alicja Karwowska

    2012-10-01

    Full Text Available We studied the effect of heavy metal cations: Fe 2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ on the activity of
    cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin
    was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg2+ cations
    inhibit the activity of cathepsin D. Cations Hg2+ damage lysosomes and release cathepsin D from these organelles.We studied the effect of heavy metal cations: Fe 2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ on the activity of
    cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin
    was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg2+ cations
    inhibit the activity of cathepsin D. Cations Hg2+ damage lysosomes and release cathepsin D from these organelles.

  1. Metal cation/anion adsorption on calcium carbonate: Implications to metal ion concentrations in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, J.M.; Cowan, C.E.; Resch, C.T.

    1990-05-01

    This chapter evaluates the sorption behavior of metallic ions on specimen calcite as a basis for determining the importance of calcite relative to other subsurface sorbents, such as layer silicates and oxides, in controlling metal ion concentration in calcareous groundwaters. A review of the literature shows the sorption of both metallic cations and anions on calcite over ranges in pH and CO{sub 2} partial pressure to be consistent with a surface-exchange process where cations exchange with surface Ca and anions exchange with surface CO{sub 3}. A general surface-exchange model was developed to account for the effects of Ca and CO{sub 3} concentrations, pH, and calcite surface area on cation and anion sorption onto calcite. The model was applied to recently developed experimental sorption data of Zn and SeO{sub 3} on specimen calcite in equilibrium CaCO{sub 3}(aq) suspensions. The surface-exchange model was able to describe the effects of pH on both cation and anion sorption, and provided good predictions of the effects of variable CO{sub 2}(g) pressure on Zn sorption and of PO{sub 4} on SeO{sub 3} sorption. The surface-exchange model, combined with sorption constants for other phases, was used to calculate Cd sorption to a hypothetical aquifer material containing a mixture of sorbents. The sorbent concentrations were fixed to those expected in groundwater zones. The multi-sorbent calculation documented the importance of calcite as a sorbent for metallic ions in groundwater.93 refs., 18 figs., 5 tabs.

  2. The quantitative relationship between metal radii, cationic radii and electronic configurations of elements

    Institute of Scientific and Technical Information of China (English)

    艾德生; 曾荣树; 叶大年

    1999-01-01

    A close relationship has been found between the metal radii, cationic radii and electronic configurations of elements. A unified formula for calculating metal radii is presented, whose paramatem are only related to the electronic configuration. Meanwhile theoretical relation between cationic radii and electronic configuration can be revealed by combining quantitative analysis with qualitative analysis. The calculated results and the charts of standard deviations are coincident with those given by reference books. Our work indicates that the metal radius and cationic radius of an element reflect in essence the element’s configuration.

  3. Assessment of Metal Toxicity in Marine Ecosystems: Comparative Toxicity Potentials for Nine Cationic Metals in Coastal Seawater

    DEFF Research Database (Denmark)

    Dong, Yan; Rosenbaum, Ralph K.; Hauschild, Michael Zwicky

    2016-01-01

    ecotoxicity data and take account of metal speciation and bioavailability. CTPs were developed for nine cationic metals (Cd, Cr(III), Co, Cu(II), Fe(III), Mn, Ni, Pb and Zn) in 64 Large Marine Ecosystems (LMEs) covering all coastal waters in the world. The results showed that the CTP of a specific metal...

  4. Effect of heavy metal cations on the activity of cathepsin D (in vitro study).

    Science.gov (United States)

    Karwowska, Alicja; Łapiński, Radosław; Gacko, Marek; Grzegorczyk, Ewa; Żurawska, Joanna; Karczewski, Jan K

    2012-01-01

    We studied the effect of heavy metal cations: Fe²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺ on the activity of cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg²⁺ cations inhibit the activity of cathepsin D. Cations Hg²⁺ damage lysosomes and release cathepsin D from these organelles. PMID:23042275

  5. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

  6. The effect of the alkali metal cation on the electrocatalytic oxidation of formate on platinum

    OpenAIRE

    Previdello, B.; E. Machado; Varela, H.

    2014-01-01

    Non-covalent interactions between hydrated alkali metal cations and adsorbed oxygenated species on platinum might considerably inhibit some electrocatalytic reactions. We report in this communication the effect exerted by electrolyte alkali metal cations on the electro-oxidation of formate ions on platinum. The system was investigated by means of cyclic voltammetry and chronoamperometry in the presence of an electrolyte containing Li+, Na+, or K+. As already observed for other systems, the ge...

  7. Prediction of mono-, bi-, and trivalent metal cation relative toxicity to the seaweed Gracilaria domingensis (Gracilariales, Rhodophyta) in synthetic seawater.

    Science.gov (United States)

    Mendes, Luiz Fernando; Zambotti-Villela, Leonardo; Yokoya, Nair Sumie; Bastos, Erick Leite; Stevani, Cassius Vinicius; Colepicolo, Pio

    2013-11-01

    The present study reports a 48-h aquatic metal-toxicity assay based on daily growth rates of the red seaweed Gracilaria domingensis (Gracilariales, Rhodophyta) in synthetic seawater. The median inhibitory concentration (IC50) for each metal cation was experimentally determined, and the ratios of free ions (aqueous complex) were calculated by software minimization of the total equilibrium activity (MINTEQA2) to determine the free median inhibitory concentration (IC50F). A model for predicting the toxicity of 14 metal cations was developed using the generic function approximation algorithm (GFA) with log IC50F values as the dependent variables and the following properties as independent variables: ionic radius (r), atomic number (AN), electronegativity (Xm ), covalent index (Xm (2) r), first hydrolysis constant (|log KOH |), softness index (σp ), ion charge (Z), ionization potential (ΔIP), electrochemical potential (ΔEo ), atomic number divided by ionization potential (AN/ΔIP), and the cation polarizing power for Z(2) /r and Z/AR. The 3-term independent variables were predicted as the best-fit model (log IC50F: -23.64 + 5.59 Z/AR + 0.99 |log KOH | + 37.05 σp ; adjusted r(2) : 0.88; predicted r(2) : 0.68; Friedman lack-of-fit score: 1.6). This mathematical expression can be used to predict metal-biomolecule interactions, as well as the toxicity of mono-, bi-, and trivalent metal cations, which have not been experimentally tested in seaweed to date. Quantitative ion-character relationships allowed the authors to infer that the mechanism of toxicity might involve an interaction between metals and functional groups of biological species containing sulfur or oxygen.

  8. Low-Temperature Cationic Rearrangement in a Bulk Metal Oxide.

    Science.gov (United States)

    Li, Man-Rong; Retuerto, Maria; Stephens, Peter W; Croft, Mark; Sheptyakov, Denis; Pomjakushin, Vladimir; Deng, Zheng; Akamatsu, Hirofumi; Gopalan, Venkatraman; Sánchez-Benítez, Javier; Saouma, Felix O; Jang, Joon I; Walker, David; Greenblatt, Martha

    2016-08-16

    Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic-scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also high pressure in bulk oxide materials. Herein, we present the cationic rearrangement in bulk Mn2 FeMoO6 at unparalleled low temperatures of 150-300 (o) C. The irreversible ionic motion at ambient pressure, as evidenced by real-time powder synchrotron X-ray and neutron diffraction, and second harmonic generation, leads to a transition from a Ni3 TeO6 -type to an ordered-ilmenite structure, and dramatic changes of the electrical and magnetic properties. This work demonstrates a remarkable cationic rearrangement, with corresponding large changes in the physical properties in a bulk oxide at unprecedented low temperatures. PMID:27203790

  9. Encapsulation of metal cations by the PhePhe ligand: a cation-pi ion cage

    NARCIS (Netherlands)

    R.C. Dunbar; J.D. Steill; J. Oomens

    2011-01-01

    Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba2+ and Ca2+, the alkali-metal ions Li+, Na+, K+, and Cs+, and the transition-metal ion Ag+. The two neighboring aromatic side chains open the possibility of a nove

  10. Encapsulation of Metal Cations by the PhePhe Ligand: A Cation-pi Ion Cage

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Oomens, J.

    2011-01-01

    Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba2+ and Ca2+, the alkali-metal ions Li+, Na+, K+, and Cs+, and the transition-metal ion Ag+. The two neighboring aromatic side chains open the possibility of a nove

  11. Structures of the dehydrogenation products of methane activation by 5d transition metal cations

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Redlich, B.; van der Meer, A. F. G.; Oomens, J.; Bakker, J. M.; Sweeney, A.; Mookherjee, A.; Armentrout, P. B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M +) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H]+ and H2. However, the structure of the dehydrogenation

  12. Structures of the Dehydrogenation Products of Methane Activation by 5d Transition Metal Cations

    NARCIS (Netherlands)

    V.J.F. Lapoutre; B. Redlich; A.F.G. Meer; J. Oomens; J.M. Bakker; A. Sweeney; A. Mookherjee; P.B. Armentrout

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M+) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H](+) and H-2. However, the structure of the dehydrogenati

  13. Hydrocolloid liquid-core capsules for the removal of heavy-metal cations from water.

    Science.gov (United States)

    Nussinovitch, A; Dagan, O

    2015-12-15

    Liquid-core capsules with a non-crosslinked alginate fluidic core surrounded by a gellan membrane were produced in a single step to investigate their ability to adsorb heavy metal cations. The liquid-core gellan-alginate capsules, produced by dropping alginate solution with magnesium cations into gellan solution, were extremely efficient at adsorbing lead cations (267 mg Pb(2+)/g dry alginate) at 25 °C and pH 5.5. However, these capsules were very weak and brittle, and an external strengthening capsule was added by using magnesium cations. The membrane was then thinned with the surfactant lecithin, producing capsules with better adsorption attributes (316 mg Pb(+2)/g dry alginate vs. 267 mg Pb(+2)/g dry alginate without lecithin), most likely due to the thinner membrane and enhanced mass transfer. The capsules' ability to adsorb other heavy-metal cations - copper (Cu(2+)), cadmium (Cd(2+)) and nickel (Ni(2+)) - was tested. Adsorption efficiencies were 219, 197 and 65 mg/g, respectively, and were correlated with the cation's affinity to alginate. Capsules with the sorbed heavy metals were regenerated by placing in a 1M nitric acid suspension for 24h. Capsules could undergo three regeneration cycles before becoming damaged.

  14. Binding properties of oxacalix[4]arenes derivatives toward metal cations; Interactions entre cations metalliques et derives des oxacalix[4]arenes

    Energy Technology Data Exchange (ETDEWEB)

    Mellah, B

    2006-11-15

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) {sup 1}H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na{sup +}, K{sup +}, Ca{sup 2+}, Pb{sup 2+} and Mn{sup 2+} of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li{sup +}, Ba{sup 2+}, Zn{sup 2+} and Hg{sup 2+}. A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs{sup +}, Ba{sup 2+}, Cu{sup 2+} and Hg{sup 2+} were noted. (author)

  15. MODIFICATION OF TRANSITION METAL CATIONS TO POLYMER- STABILIZED PLATINUM COLLOIDAL CLUSTERS IN ENANTIOSELECTIVE HYDROGENATION OF METHYL PYRUVATE

    Institute of Scientific and Technical Information of China (English)

    Xiao-ping Yan; Bao-lin He; Jie Zhang; Han-fan Liu

    2005-01-01

    Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate. Compared to the enantiomeric excess (e.e.) value (71.4%)obtained without the presence of metal cations, obvious e.e. enhancement (up to 82.5%) was resulted from the addition of Zn2+ but with a certain decrease in activity. The reaction parameters in the presence of Zn2+ were also studied. It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.

  16. Multicenter bond index analysis of influence of metal cations on the aromaticity of aromatic amino acids: Phenylalanine and tyrosine

    Science.gov (United States)

    Pakiari, A. H.; Farrokhnia, M.; Azami, S. M.

    2008-05-01

    In order to provide insight into the influence of metal cations on the aromaticity of amino acids, evaluation of six-center delocalization indices is accomplished in the context of quantum theory of atoms in molecules (QTAIM). Aromaticity of two amino acids, phenylalanine and tyrosine, is investigated as typical amino acids containing aromatic ring in their isolated state and complexed by some metal cations. The results showed that the metal cations affect the most important three connectivities differently. Also, it is shown that the existence of metal cations can increase two-center delocalization in certain parts of the aromatic rings.

  17. A Bioluminescence Assay System for Imaging Metal Cationic Activities in Urban Aerosols.

    Science.gov (United States)

    Kim, Sung-Bae; Naganawa, Ryuichi; Murata, Shingo; Nakayama, Takayoshi; Miller, Simon; Senda, Toshiya

    2016-01-01

    A bioluminescence-based assay system was fabricated for an efficient determination of the activities of air pollutants. The following four components were integrated into this assay system: (1) an 8-channel assay platform uniquely designed for simultaneously sensing multiple optical samples, (2) single-chain probes illuminating toxic chemicals or heavy metal cations from air pollutants, (3) a microfluidic system for circulating medium mimicking the human body, and (4) the software manimulating the above system. In the protocol, we briefly introduce how to integrate the components into the system and the application to the illumination of the metal cationic activities in air pollutants. PMID:27424913

  18. A Bioluminescence Assay System for Imaging Metal Cationic Activities in Urban Aerosols.

    Science.gov (United States)

    Kim, Sung-Bae; Naganawa, Ryuichi; Murata, Shingo; Nakayama, Takayoshi; Miller, Simon; Senda, Toshiya

    2016-01-01

    A bioluminescence-based assay system was fabricated for an efficient determination of the activities of air pollutants. The following four components were integrated into this assay system: (1) an 8-channel assay platform uniquely designed for simultaneously sensing multiple optical samples, (2) single-chain probes illuminating toxic chemicals or heavy metal cations from air pollutants, (3) a microfluidic system for circulating medium mimicking the human body, and (4) the software manimulating the above system. In the protocol, we briefly introduce how to integrate the components into the system and the application to the illumination of the metal cationic activities in air pollutants.

  19. Enthalpy-entropy compensation for n-hexane adsorption on Y zeolite containing transition metal cations

    Directory of Open Access Journals (Sweden)

    Hercigonja R.

    2015-01-01

    Full Text Available In this work, the values of entropy changes related to n-hexane adsorption onto cation exchanged Y zeolite were calculated from differential heats. Various transition metal cations (Co2+, Ni2+, Zn2+ and Cd2+ were introduced into the lattice of the parent NaY, and the existence of enthalpy-entropy compensation effect related to n-hexane adsorption, id. est, the linearity of -ΔH vs. -ΔS plots was examined. The compensation effect was confirmed for all investigated zeolites. The compensation effect can be comprehended as governed by ion-induced dipole interaction between highly polarizing cationic centers in zeolite and nonopolar n-hexane molecules. Finally, the compensation effect and so the compensation temperature were found to depend on the type of charge-balancing cation (charge, size and electronic configuration. [Projekat Ministarstva nauke Republike Srbije, br. 172018

  20. Tris(triazole) tripodal receptors as selective probes for citrate anion recognition and multichannel transition and heavy metal cation sensing.

    Science.gov (United States)

    González, María del Carmen; Otón, Francisco; Espinosa, Arturo; Tárraga, Alberto; Molina, Pedro

    2015-02-01

    The three-armed pyrenyl-triazole receptor 1 behaves as a highly selective fluorescent molecular sensor for citrate anions over similar carboxylates such as malate or tartrate. In addition, this receptor senses Cu(2+) cations through absorption and emission channels even in the presence of Hg(2+) metal cations. The related three-armed ferrocenyl-triazole receptor 2 behaves as a highly selective dual (redox and chromogenic) chemosensor molecule for Pb(2+) metal cations.

  1. MRI probes for sensing biologically relevant metal ions.

    Science.gov (United States)

    Bonnet, Célia S; Tóth, Eva

    2010-03-01

    Given the important role of metal ions in fundamental biological processes, the visualization of their concentration in living animals by repeatable, noninvasive imaging techniques, such as MRI, would be highly desirable. A large number of metal-responsive MRI contrast agents, the majority based on Gd(3+) complexes, have been reported in recent years. The contrast-enhancing properties (relaxivity) of a Gd(3+) complex can be most conveniently modulated by interaction with the sensed metal cation via changes in the number of water molecules bound directly to Gd(3+) or changes in the size of the complex, which represent the two major strategies to develop metal sensitive MRI probes. Here, we survey paramagnetic lanthanide complexes involving Gd(3+) agents and paramagnetic chemical exchange saturation transfer probes designed to detect the most important endogenous metal ions: calcium, zinc, iron and copper. Future work will likely focus on extending applications of these agents to living animals, as well as on exploring new ways of creating molecular MRI probes in order to meet requirements such as higher specificity or lower detection limits.

  2. Nitrogen-Rich Multinuclear Ferrocenophanes as Multichannel Chemosensor Molecules for Transition and Heavy-Metal Cations

    Directory of Open Access Journals (Sweden)

    Antonia Sola

    2014-08-01

    Full Text Available [m.n] Multinuclear ferrocenophanes prepared by aza-Wittig reaction of bisiminophosphoranes derived from 1,1'-diazidoferrocene and isophthaladelhyde or 2,5-diformylthiophene, behave as efficient electrochemical and chromogenic chemosensor molecules for Zn2+, Pb2+, and Hg2+ metal cations. Whereas the OSWV of receptor 3, bearing two m-phenylene units in the bridges, display one oxidation peak, receptor 4 incorporating two thiophene rings in the bridges, exhibits two well-separated oxidation peaks. In both receptors only the addition of Zn2+, Pb2+, and Hg2+ metal cations induced a remarkable anodic shift of ferrocene/ferrocenium redox couple. Likewise, in the absorption spectra of these receptors the low energy band is red-shifted by Δλ = 165 − 209 nm, and these changes promoted a significant color changes which could be used for the naked eye detection of these metal cations. The coordination modes for two representative cases were unveiled by DFT calculations that show an unsual coordination in the [42Pb]2+ complex with the Pb2+ cation in a distorted cubic N4S4 donor cage.

  3. Toxic effect of metal cation binary mixtures to the seaweed Gracilaria domingensis (Gracilariales, Rhodophyta).

    Science.gov (United States)

    Mendes, Luiz Fernando; Stevani, Cassius Vinicius; Zambotti-Villela, Leonardo; Yokoya, Nair Sumie; Colepicolo, Pio

    2014-01-01

    The macroalga Gracilaria domingensis is an important resource for the food, pharmaceutical, cosmetic, and biotechnology industries. G. domingensis is at a part of the food web foundation, providing nutrients and microelements to upper levels. As seaweed storage metals in the vacuoles, they are considered the main vectors to magnify these toxic elements. This work describes the evaluation of the toxicity of binary mixtures of available metal cations based on the growth rates of G. domingensis over a 48-h exposure. The interactive effects of each binary mixture were determined using a toxic unit (TU) concept that was the sum of the relative contribution of each toxicant and calculated using the ratio between the toxicant concentration and its endpoint. Mixtures of Cd(II)/Cu(II) and Zn(II)/Ca(II) demonstrated to be additive; Cu(II)/Zn(II), Cu(II)/Mg(II), Cu(II)/Ca(II), Zn(II)/Mg(II), and Ca(II)/Mg(II) mixtures were synergistic, and all interactions studied with Cd(II) were antagonistic. Hypotheses that explain the toxicity of binary mixtures at the molecular level are also suggested. These results represent the first effort to characterize the combined effect of available metal cations, based on the TU concept on seaweed in a total controlled medium. The results presented here are invaluable to the understanding of seaweed metal cation toxicity in the marine environment, the mechanism of toxicity action and how the tolerance of the organism.

  4. Heavy metals in equine biological components

    Directory of Open Access Journals (Sweden)

    Maria Verônica de Souza

    2014-02-01

    Full Text Available The objective of this research was to determine the concentration of heavy metals in the blood (Pb, Ni and Cd, serum (Cu and Zn and hair (Pb, Ni, Cd, Cu and Zn of horses raised in non-industrial and industrial areas (with steel mill, and to verify the possibility to use these data as indicators of environmental pollution. The samples were collected during summer and winter, aiming to verify animal contamination related to environment and season of the year. Copper and Zn contents determined in the serum and Cd and Ni contents obtained in the blood indicated no contamination effects of industries. For some animals, contents of Pb in the blood were higher than those considered acceptable for the species, but without relationship with industrialization and without clinical signs of Pb intoxication. The heavy metals evaluated on the hair of horses in this study were not increased with the presence of industries, but Cu and Cd contents were influenced by the season. The contents of some heavy metals in biological components analyzed were influenced by season sampling; however, serum, blood and hair may not be suitable to indicate differences in environmental contamination between the two contrasting areas. Most part of the heavy metal contents was lower or close to the reference values for horses. Serum, blood and hair components from horses may not be effective as indicators of environmental pollution with heavy metals. Industrialization and seasons have no effects on most part of heavy metals contents from those components.

  5. A high-performance "sweeper" for toxic cationic herbicides: an anionic metal-organic framework with a tetrapodal cage.

    Science.gov (United States)

    Jia, Yan-Yuan; Zhang, Ying-Hui; Xu, Jian; Feng, Rui; Zhang, Ming-Shi; Bu, Xian-He

    2015-12-21

    This communication reports a novel metal-organic framework exhibiting an excellent performance in adsorbing small toxic cationic herbicides, i.e. methyl viologen and diquat, with large adsorption capacities and ultratrace residue levels. To the best of our knowledge, this is the first example of high-performance MOFs trapping toxic cationic herbicides. PMID:26468513

  6. Interparticle migration of metal cations in stream sediments as a factor in toxics transport

    Science.gov (United States)

    Jackman, A.P.; Kennedy, V.C.; Bhatia, N.

    2001-01-01

    Sorption of metal cations by stream sediments is an important process affecting the movement of released contaminants in the environment. The ability of cations to desorb from one sediment particle and subsequently sorb to another can greatly affect metal transport rates but rates for this process have not been reported. The objective of this study was to determine the rate at which sorbed metals can migrate from contaminated sediment particles to uncontaminated sediment particles as a function of the concentration of the contaminating solution and the duration of the contact with the contaminating solution. Samples of small sediment particles were exposed to solutions containing cobalt, after which they were rinsed and combined with larger uncontaminated sediment particles in the presence of stream water. Initial concentrations of the contaminating solution ranged from 1ng/l to 1000mg/l and exposures to the contaminating solution ranged from 6h to 14 days. The rate of the migration increased with increasing concentrations in the contaminating solution and with decreasing times of exposure to the contaminating solution. Under the conditions of these experiments, the time required for the migration to reach equilibrium was on the order of months or longer. In separate experiments, the kinetics of adsorption and desorption of cobalt were measured as a function of concentration of the contaminating solution. The time required to reach adsorption equilibrium increased with increasing concentration in the contaminating solution. Times to sorption equilibrium were on the order of months. Desorption was much slower than adsorption and, together with intraparticle diffusion, probably controls the rate of migration from contaminated to uncontaminated sediment. The results of this study show that interparticle migration of metal cations can proceed at significant rates that are strongly influenced by the length of time that the metal has been in contact with the sediment

  7. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C; Holt-Larese, Kathleen C; Bontchev, Ranko

    2013-08-13

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  8. Multi-physical model of cation and water transport in ionic polymer-metal composite sensors

    Science.gov (United States)

    Zhu, Zicai; Chang, Longfei; Horiuchi, Tetsuya; Takagi, Kentaro; Aabloo, Alvo; Asaka, Kinji

    2016-03-01

    Ion-migration based electrical potential widely exists not only in natural systems but also in ionic polymer materials. We presented a multi-physical model and investigated the transport process of cation and water of ionic polymer-metal composites based on our thorough understanding on the ionic sensing mechanisms in this paper. The whole transport process was depicted by transport equations concerning convection flux under the total pressure gradient, electrical migration by the built-in electrical field, and the inter-coupling effect between cation and water. With numerical analysis, the influence of critical material parameters, the elastic modulus Ewet, the hydraulic permeability coefficient K, the diffusion coefficient of cation dII and water dWW, and the drag coefficient of water ndW, on the distribution of cation and water was investigated. It was obtained how these parameters correlate to the voltage characteristics (both magnitude and response speed) under a step bending. Additionally, it was found that the effective relative dielectric constant ɛr has little influence on the voltage but is positively correlated to the current. With a series of optimized parameters, the predicted voltage agreed with the experimental results well, which validated our model. Based on our physical model, it was suggested that an ionic polymer sensor can benefit from a higher modulus Ewet, a higher coefficient K and a lower coefficient dII, and a higher constant ɛr.

  9. New generation super alloy candidates for medical applications: corrosion behavior, cation release and biological evaluation.

    Science.gov (United States)

    Reclaru, L; Ziegenhagen, R; Unger, R E; Eschler, P Y; Constantin, F

    2014-12-01

    Three super alloy candidates (X1 CrNiMoMnW 24-22-6-3-2 N, NiCr21 MoNbFe 8-3-5 AlTi, CoNiCr 35-20 Mo 10 BTi) for a prolonged contact with skin are evaluated in comparison with two reference austenitic stainless steels 316L and 904L. Several electrochemical parameters were measured and determined (E(oc), E(corr), i(corr), b(a), b(c), E(b), R(p), E(crev) and coulometric analysis) in order to compare the corrosion behavior. The cation release evaluation and in vitro biological characterization also were performed. In terms of corrosion, the results reveal that the 904L steels presented the best behavior followed by the super austenitic steel X1 CrNiMoMnW 24-22-6-3-2 N. For the other two super alloys (NiCr and CoNiCr types alloys) tested in different conditions (annealed, work hardened and work hardened+age hardened) it was found that their behavior to corrosion was weak and close to the other reference stainless steel, 316L. Regarding the extraction a mixture of cations in relatively high concentrations was noted and therefore a cocktail effect was not excluded. The results obtained in the biological assays WST-1 and TNF-alpha were in correlation with the corrosion and extraction evaluation. PMID:25491846

  10. Transition metal cations extraction by ester and ketone derivatives of chromogenic azocalix[4]arenes.

    Science.gov (United States)

    Ak, Metin; Taban, Deniz; Deligöz, Hasalettin

    2008-06-15

    The molecule of azocalix[n]arene is a macrocyclic used effectively in the complexation of the heavy metal pollutants (like silver and mercury). In this work, our main aim is to prepare new chromogenic azocalix[n]arene molecules to elaborate an extractant with high extractant selectivity for metal ions able to detect this type of pollutant. The solvent extraction properties of four acetyls, four methyl ketones and four benzoyls derivatives from azocalix[4]arenes which were prepared by linking 4-ethyl, 4-n-butyl, 4-acetamid anilin and 2-aminothiazol to calix[4]arene through a diazo-coupling reaction, the alkaline earth (Sr2+) and the transition (Ag+, Hg2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Cr3+) metal cations have been determined by extraction studies with metal picrates. Both ketones are better extractants than esters, and show a strong preference for Ag+, while Cu2+ and Cr3+ are the most extracted cation with the esters. Both acetyl and benzoyl esters are good carriers for Ag+ and Hg2+.

  11. Investigation of biologically-designed metal-specific chelators for potential metal recovery and waste remediation applications.

    Energy Technology Data Exchange (ETDEWEB)

    Criscenti, Louise Jacqueline; Ockwig, Nathan W.

    2009-01-01

    Bacteria, algae and plants produce metal-specific chelators to capture required nutrient or toxic trace metals. Biological systems are thought to be very efficient, honed by evolutionary forces over time. Understanding the approaches used by living organisms to select for specific metals in the environment may lead to design of cheaper and more effective approaches for metal recovery and contaminant-metal remediation. In this study, the binding of a common siderophore, desferrioxamine B (DFO-B), to three aqueous metal cations, Fe(II), Fe(III), and UO{sub 2}(VI) was investigated using classical molecular dynamics. DFO-B has three acetohydroxamate groups and a terminal amine group that all deprotonate with increasing pH. For all three metals, complexes with DFO-B (-2) are the most stable and favored under alkaline conditions. Under more acidic conditions, the metal-DFO complexes involve chelation with both acetohydroxamate and acetylamine groups. The approach taken here allows for detailed investigation of metal binding to biologically-designed organic ligands.

  12. Changes in the Vibrational Spectra of Zeolites Due to Sorption of Heavy Metal Cations

    Science.gov (United States)

    Król, M.; Mozgawa, W.; Barczyk, K.; Bajda, T.; Kozanecki, M.

    2013-11-01

    This work presents the results of spectroscopic (MIR and Raman) studies of zeolite structures after immobilization of heavy metal cations from aqueous solutions. The sorption of Ag+, Cu2+, Cd2+, Pb2+, Zn2+, and Cr3+ ions has been conducted on zeolites belonging to different structural groups, i.e., sodium forms of natural chabazite, mordenite, ferrierite, and clinoptilolite, as well as on synthetic zeolite Y. Systematic changes in intensities and positions of the bands corresponding to the characteristic ring vibrations have been observed in the measured spectra. The most visible changes are observed in the FT-IR spectra of the samples in the range of 850-450 cm-1, and in the Raman spectra in the range of 600-250 cm-1. Depending on the zeolite structure, the bands, which can be regarded as a kind of indicator of ion exchange, were indentifi ed. For example, in the case of IR spectra, these bands are at 766, 703, 648, 578, and 506 cm-1 for zeolite Y, at 733 and 560 cm-1 for mordenite, at 675 cm-1 for clinoptilolite, etc. The degree of changes depends on both the type of cation and its concentration in the initial solution. This is connected with the way of binding of metal ions to the zeolite aluminosilicate framework, i.e., a proportion of the ion exchange and chemisorption in the process. Cations mainly undergoing ion exchange, such as Cd2+ or Pb2+, have the greatest impact on the character of the spectra. On the other hand, Cr3+ ions practically do not modify the spectra of zeolites. Results of IR and Raman spectroscopic studies have been compared with those obtained by atomic absorption spectroscopy (AAS), from which the proportion of ion exchange to chemisorption in the process and the effective cation exchange capacity of the individual samples have been estimated.

  13. Fingernails as biological indices of metal exposure

    Indian Academy of Sciences (India)

    Rita Mehra; Meenu Juneja

    2005-03-01

    Metal determination in human tissues is the most common application of biological monitoring for screening, diagnosis and assessment of metal exposures and their risks. Various biopsy-materials may be used. This paper deals with the quantitative determination of Cd, Pb, Cr, Mn, Fe, Ni, Cu, and Zn concentrations in nails of male subjects exposed to these metals alongwith their respective controls, while working in locomotive, carriage and roadways workshops, and lead battery factories. The levels of Cd, Pb, Cr, Mn, Fe, Ni, Cu and Zn in fingernails, assayed by atomic absorption spectrophotometry, were compared with their respective controls by student ‘’ test. All the obtained values were correlated to the personal and medical history of the subjects under study. Significantly high levels of Cd, Pb, Cr, Fe, Ni, Cu and Zn were present in smokers, compared to nonsmokers. The concentrations of Cd, Pb, Cr, Mn and Fe were not significantly high in vegetarian subjects. It was also observed that there is no contribution of liquor towards nail-metal concentration. Significant correlations were observed between skin disease and Cr, Mn, Fe, Cu; hypertension and Cd, Mn, Cu; mental stress and Cd, Pb, Mn, Ni, Cu, Zn; diabetes and Cr, Mn, Ni; chest pain and Pb; respiratory trouble and Cr, Mn, Fe, Ni, Zn; tuberculosis and Zn; acidity and Cd; and ophthalmic problems and Mn, Fe, Ni, and Zn.

  14. A review of modelling the interaction between natural organic matter and metal cations

    International Nuclear Information System (INIS)

    This report reviews techniques available to model the interaction between natural organic matter (mainly fulvic and humic acids) and metal cations and protons. A comprehensive overview over the properties of natural organic matter is given and experimental techniques are presented briefly. Two major concepts of modelling have been identified: discrete ligand models and continuous distribution model. Different modelling approaches like Discrete Ligand Models (s.s.), Random-Structure Model, Affinity Spectra, Statistical Distribution Models, Continuous Stability Function Models and surface sorption models and their advantages/disadvantages are discussed. (author)

  15. HNS+ and HSN+ cations: Electronic states, spin-rovibronic spectroscopy with planetary and biological implications

    Science.gov (United States)

    Trabelsi, Tarek; Ben Yaghlane, Saida; Al Mogren, Muneerah Mogren; Francisco, Joseph S.; Hochlaf, Majdi

    2016-08-01

    Ab initio methods in conjunction with a large basis set are used to compute the potential energy surfaces of the 12 lowest electronic states of the HNS+ and HSN+ isomeric forms. These potentials are used in discussions of the metastability of these cations and plausible mechanisms for the H+/H + SN+/SN, S/S+ + NH+/NH, N/N+ + SH+/SH ion-molecule reactions. Interestingly, the low rovibrational levels of HSN+(12A″) and HNS+(12A″) electronically excited ions are predicted to be long-lived. Both ions are suggested to be a suitable candidate for light-sensitive NOṡ donor in vivo and as a possible marker for the detection of intermediates in nitrites + H2S reactions at the cellular level. The full spin rovibronic levels of HNS+ are presented, which may assist in the experimental identification of HNS+ and HSN+ ions and in elucidating their roles in astrophysical and biological media.

  16. Resorcarene-based receptor: versatile behavior in its interaction with heavy and soft metal cations.

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K; Piro, Oscar E; Castellano, Eduardo E

    2006-02-01

    Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal

  17. Resorcarene-based receptor: versatile behavior in its interaction with heavy and soft metal cations.

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K; Piro, Oscar E; Castellano, Eduardo E

    2006-02-01

    Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal

  18. A Water-Stable Cationic Metal-Organic Framework as a Dual Adsorbent of Oxoanion Pollutants.

    Science.gov (United States)

    Desai, Aamod V; Manna, Biplab; Karmakar, Avishek; Sahu, Amit; Ghosh, Sujit K

    2016-06-27

    A three-dimensional water-stable cationic metal-organic framework (MOF) pillared by a neutral ligand and with Ni(II)  metal nodes has been synthesized employing a rational design approach. Owing to the ordered arrangement of the uncoordinated tetrahedral sulfate (SO4 (2-) ) ions in the channels, the compound has been employed for aqueous-phase ion-exchange applications. The compound exhibits rapid and colorimetric aqueous-phase capture of environmentally toxic oxoanions (with similar geometries) in a selective manner. This system is the first example of a MOF-based system which absorbs both dichromate (Cr2 O7 (2-) ) and permanganate (MnO4 (-) ) ions, with the latter acting as a model for the radioactive contaminant pertechnetate (TcO4 (-) ). PMID:26855323

  19. A review of modelling the interaction between natural organic matter and metal cations

    International Nuclear Information System (INIS)

    This report reviews techniques available to model the interaction between natural organic matter (mainly fulvic and humic acids) and protons and metal cations. A concise definition of natural organic matter is given and their properties are outlined. These materials are macromolecules which exhibit a polyelectrolyte character owing to numerous dissociable functional groups which are attached to their carbon backbone or from integral parts of the structure. The polyelectrolyte character is thought to be responsible for their conformation, hydrogen bonding or bridging by metal cations between subunits being important mechanisms. Environmental parameters like pH and ionic strength thus will have profound effects on the conformation of natural organic matter, the properties of which can change from being a flexible polymer to being a rigid gel. Binding mechanisms and binding strengh are discussed and an overview of relevant techniques of investigation is given. This work is part of the Commission's Mirage project - Phase 2, research area Geochemistry of actinides and fission products in natural aquifer systems

  20. Transition metal cation separations with a resorcinarene-based amino acid stationary phase.

    Science.gov (United States)

    Li, Na; Allen, Lee J; Harrison, Roger G; Lamb, John D

    2013-03-01

    A resorcinarene-based macrocyclic ligand functionalized with alanine and undecyl groups (AUA) was synthesized and applied to ion chromatographic separations. The selectivity and separation of transition metal ions on a column packed with AUA adsorbed onto 55% cross-linked styrene-divinylbenzene resin are presented. The upper and lower rims of the resorcinarene were modified with amino acids and -C(11)H(23) alkyl chains, respectively. The four carboxylic acid groups on the upper rim act as cation-exchangers while the four -C(11)H(23) alkyl chains serve to anchor the ligand to the resin surface by the hydrophobic effect. A systematic study of the effect of different eluent components including non-metal-chelating (HNO(3)) and chelating acids (oxalic acid, succinic acid, dipicolinic acid, and citric acid) on the retention of transition metal ions was investigated. Six metal ions (Mn(2+), Co(2+), Ni(2+), Cd(2+), Cu(2+), and Zn(2+)) were separated on the AUA column within a reasonable time with a single eluent gradient using oxalic acid. The separation is compared to that obtained using a commercial column containing carboxylic acid functional groups. The AUA column containing four preorganized carboxylic acid groups showed selectivity for Cu(2+) when no chelating eluent was present, a selectivity which was not observed with the comparison column.

  1. Host--guest complexation. 15. Macrocyclic acetylacetone ligands for metal cations

    International Nuclear Information System (INIS)

    Five macrocycles containing 1,5-disubstituted acetylacetone units (AcAc) have been synthesized. Their abilities to complex metal cations in water--dioxane have been compared to those of noncyclic model compounds. The AcAc units were bound together through bridges composed of the following groups: oxa (O), ethylene (E), and 1,3-disubstituted benzene (B). Cycles O(AcAcOEOE)(EOEOE)O(7), (OEOAcAcOE)2 (8), and (OEOAcAcOE)3 (9) were prepared by hydrolysis of rings closed by the reactions of CH2[HOCH2C(SCH2)2CH2]2 (2) and appropriate polyethylene glycol ditosylates. Ligand systems O(EAcAcE)2O (12) and B(CH2AcAcCH2)2B (14) were synthesized in Ca2+ or Mg2+ templated, two-step sequences involving reactions of HAcAcH dianions with either diethylene glycol ditosylate of m-xylyl dibromide, respectively. The preparation of (CH2IsCH2O)3 (17) is also described, in which Is is the 3,5-disubstituted isoxazole unit. Also described are the preparations of O(EAcAcH)2 (11), B(CH2AcAcH)2 (13), and P(CH2AcAcH)2 (15), in which P is 2,6-disubstituted pyridine. The logarithms of the formation constants (log K/sup f//sub av/) of the salts of (OEOAcAcOE)2 with 11 divalent metal cations and of (OEOAcAcOE)3 with 3 trivalent cations were 1.8 to 6.3 units higher valued than for CH3OAcAcOCH3. The log K/sup f//sub av/values for salt formation of O(EAcAcE)2O and B(CH2AcAcCH2)2B with 10 divalent cations were compared with those of O(EAcAcH)2 and B(CH2AcAcH)2, respectively, and with HAcAcH itself. Without exception, O(EAcAcE)2O > O(EAcAcH)2 > HAcAcH in values of log k/sup f//sub av/, the maximum difference being 4.3 for Ca2+

  2. Structures of the dehydrogenation products of methane activation by 5d transition metal cations.

    Science.gov (United States)

    Lapoutre, V J F; Redlich, B; van der Meer, A F G; Oomens, J; Bakker, J M; Sweeney, A; Mookherjee, A; Armentrout, P B

    2013-05-23

    The activation of methane by gas-phase transition metal cations (M(+)) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H](+) and H2. However, the structure of the dehydrogenation product has not been established unambiguously. Two types of structures have been considered: a carbene structure where an intact CH2 fragment is bound to the metal (M(+)-CH2) and a carbyne (hydrido-methylidyne) structure with both a CH and a hydrogen bound to the metal separately (H-M(+)-CH). For metal ions with empty d-orbitals, an agostic interaction can occur that could influence the competition between carbene and carbyne structures. In this work, the gas phase [M,C,2H](+) (M = Ta, W, Ir, Pt) products are investigated by infrared multiple-photon dissociation (IR-MPD) spectroscopy using the Free-Electron Laser for IntraCavity Experiments (FELICE). Metal cations are formed in a laser ablation source and react with methane pulsed into a reaction channel downstream. IR-MPD spectra of the [M,C,2H](+) species are measured in the 300-3500 cm(-1) spectral range by monitoring the loss of H (2H in the case of [Ir,C,2H](+)). For each system, the experimental spectrum closely resembles the calculated spectrum of the lowest energy structure calculated using DFT: for Pt, a classic C(2v) carbene structure; for Ta and W, carbene structures that are distorted by agostic interactions; and a carbyne structure for the Ir complex. The Ir carbyne structure was not considered previously. To obtain this agreement, the calculated harmonic frequencies are scaled with a scaling factor of 0.939, which is fairly low and can be attributed to the strong redshift induced by the IR multiple-photon excitation process of these small molecules. These four-atomic species are among the smallest systems studied by IR-FEL based IR-MPD spectroscopy, and their spectra demonstrate the power of IR

  3. Fluorescent heavy metal cation sensing with water dispersible 2MPA capped CdSe/ZnS quantum dots

    International Nuclear Information System (INIS)

    Here we report the fluorescence response of water dispersible CdSe/ZnS core–shell quantum dots capped with 2-mercaptopropionic acid (2MPA) towards different concentrations of heavy metal cations, namely mercury, lead and cadmium. Upon exposure to different concentrations of the various metal cations, a concentration-dependent decrease in the QDs’ fluorescence emission was observed, which was decaying exponential in nature. The greatest degree of quenching was achieved in the presence of mercury. The resultant quantum dots were subsequently characterised by UV–vis spectroscopy, photo-luminescent spectroscopy, Raman Spectroscopy and X-ray diffraction. The quantitative detection of mercury, lead and cadmium cations by these capped quantum dots makes them exciting candidates for heavy metal sensing applications

  4. Fluorescent heavy metal cation sensing with water dispersible 2MPA capped CdSe/ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, D., E-mail: vasudevand@rediffmail.com [Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu (India); Trinchi, Adrian; Hardin, Simon G.; Cole, Ivan S. [CSIRO Materials Science and Engineering, Private Bag 33, Clayton South MDC 3169 (Australia)

    2015-10-15

    Here we report the fluorescence response of water dispersible CdSe/ZnS core–shell quantum dots capped with 2-mercaptopropionic acid (2MPA) towards different concentrations of heavy metal cations, namely mercury, lead and cadmium. Upon exposure to different concentrations of the various metal cations, a concentration-dependent decrease in the QDs’ fluorescence emission was observed, which was decaying exponential in nature. The greatest degree of quenching was achieved in the presence of mercury. The resultant quantum dots were subsequently characterised by UV–vis spectroscopy, photo-luminescent spectroscopy, Raman Spectroscopy and X-ray diffraction. The quantitative detection of mercury, lead and cadmium cations by these capped quantum dots makes them exciting candidates for heavy metal sensing applications.

  5. Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

    Indian Academy of Sciences (India)

    K V Amrute; U R Mhatre; S K Sinha; D C Kothari; R Nagarajan; D Kanjilal

    2002-05-01

    Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5 × 1013 and 7.5 × 1013 ions/cm2. The relative intensity ratios 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.

  6. “High-Throughput” Evaluation of Polymer-Supported Triazolic Appendages for Metallic Cations Extraction

    Directory of Open Access Journals (Sweden)

    Riadh Slimi

    2015-03-01

    Full Text Available The aim of this work was to find and use a low-cost high-throughput method for a quick primary evaluation of several metal extraction by substituted piperazines appendages as chelatants grafted onto Merrifield polymer using click-chemistry by the copper (I-catalyzed Huisgen’s reaction (CuAAC The polymers were tested for their efficiency to remove various metal ions from neutral aqueous solutions (13 cations studied: Li+, Na+, K+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Cd2+, Ba2+, Ce3+, Hg+ and Pb2+ using the simple conductimetric measurement method. The polymers were found to extract all metals with low efficiencies ≤40%, except for Fe3+ and Hg+, and sometimes Pb2+. Some polymers exhibited a selectively for K+, Cd2+ and Ba2+, with good efficiencies. The values obtained here using less polymer, and a faster method, are in fair correspondence (average difference ±16% with another published evaluation by atomic absorption spectroscopy (AAS.

  7. Alkali metal cation doping of metal-organic framework for enhancing carbon dioxide adsorption capacity

    Institute of Scientific and Technical Information of China (English)

    Yan Cao; Yunxia Zhao; Fujiao Song; Qin Zhong

    2014-01-01

    Metal-organic frameworks (MOFs) have attracted much attention as adsorbents for the separation of CO2 from flue gas or natural gas. Here, a typical metal-organic framework HKUST-1(also named Cu-BTC or MOF-199) was chemically reduced by doping it with alkali metals (Li, Na and K) and they were further used to investigate their CO2 adsorption capacities. The structural information, surface chemistry and thermal behavior of the prepared adsorbent samples were characterized by X-ray powder diffraction (XRD), thermo-gravimetric analysis (TGA) and nitrogen adsorption-desorption isotherm analysis. The results showed that the CO2 storage capacity of HKUST-1 doped with moderate quantities of Li+, Na+ and K+, individually, was greater than that of unmodified HKUST-1. The highest CO2 adsorption uptake of 8.64 mmol/g was obtained with 1K-HKUST-1, and it was ca. 11%increase in adsorption capacity at 298 K and 18 bar as compared with HKUST-1. Moreover, adsorption tests showed that HKUST-1 and 1K-HKUST-1 displayed much higher adsorption capacities of CO2 than those of N2. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of 1K-HKUST-1 was fairly stable, without obvious deterioration in the adsorption capacity of CO2 after 10 cycles.

  8. CO 2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: A molecular simulation study

    KAUST Repository

    Chen, Yifei

    2012-02-28

    A molecular simulation study is reported for CO 2 adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na +, K +, Rb +, Cs +, Mg 2+, Ca 2+, and Al 3+). The isosteric heat and Henry\\'s constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ < Al 3+). At low pressures, cations act as preferential adsorption sites for CO 2 and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO 2 adsorption. Furthermore, the adsorption selectivity of CO 2/H 2 mixture increases as Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ ≈ Al 3+. At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H 2O, the selectivity decreases drastically because of the competitive adsorption between H 2O and CO 2, and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations. © 2012 American Chemical Society.

  9. Study of the interaction metallic cation - ligand in concentrated phosphorus acid media; Etude de l'interaction cation metallique - ligand en milieu acide phosphorique concentre

    Energy Technology Data Exchange (ETDEWEB)

    Sefiani, N.; Azzi, M.; Hlaibi, M. [Faculte des Sciences Ain Chock, Laboratoire d' Electrochimie et Chimie de l' Environnement (LECE), Casablanca (Morocco); Kossair, A. [Centre de Recherche des Phosphates Mineraux (CERPHOS), Casablanca (Morocco)

    2005-07-01

    The phosphoric acid is more and more used with a high purity. The recovery of recycling element (uranium, vanadium, rare earth...) and the elimination of toxic element (cadmium, molybdenum, lead...) contained in the phosphoric acid are generally realized by extraction or precipitation. It is then very important to understand these impurities behavior in the phosphoric media in order to control their elimination. In this work, the authors considered the presence of some metallic cations (V, Al, fe, U) and fluorides ions as impurity in concentrated phosphoric acid media. (A.L.B.)

  10. Theoretical Studies on the Interaction between Metal Cations and Cytosine, Guanine

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ya-Ying; ZHOU Li-Xin; WAN Hua-Ping

    2005-01-01

    The interaction of tetra- and hexa-coordinated compounds of cytosine(C) and guanine(G) with metal cations Ca2+, Mg2+, Mn2+, Ni2+, Cu2+, and Zn2+ have been calculated by using the B3LYP/6-31G method at the 6-31G(d, p) basis set, while the remaining coordination bonds are saturated by water molecules ((H2O)4).All geometries were optimized without symmetry restrictions.Comparing the interaction energies we obtained the orders of selectivity of C and G for the above metal ions as follows: aCu2+>aNi2+>aZn2+>aMg2+>bCu2+>aMn2+>bZn2+>bNi2+ and aCu2+> aNi2+>aZn2+>aMg2+>bCu2+>aMn2+>bZn2+>bNi2, respectively (a, b represent tetra- and hexa-coordinated, respectively), which are in good agreement with the experimental facts.Interaction energies of complexes provide a comparatively reliable quantification of the selectivity of dimethyl phosphate anion for the studied metal ions.In addition, the influence of coordination number and coordination structure on the interaction energy and the variation of ionic energy were discussed sufficiently.After analyzing the interaction energies of two kinds of complexes, the "mutual selectivity"as well as the nature of the interaction between metal ions and ligands was revealed.

  11. Effect of heavy metal cations on the fate of extracellular DNA adsorbed and bound on clay minerals.

    OpenAIRE

    Ascher J.; Ceccherini M.T.; Arfaioli P.; Borgogni F.; Pietramellara G.

    2011-01-01

    The presence of high-valent metal cations on clay mineral surfaces is hypothesised to induce conformational changes in the secondary and tertiary structure of the DNA molecule adsorbed and bound onto clays, defined as M-conformation, and its condensation. The hypothesis that these reversible phenomena could enhance the resistance of DNA to enzymatic degradation strongly encourages the studies on the effects of heavy metal contamination in clay rich soils on the fate of extracellular soil DNA ...

  12. Effects of Acetate on Cation Exchange Capacity of a Zn-Containing Montmorillonite : Physicochemical Significance and Metal Uptake

    NARCIS (Netherlands)

    Stathi, P.; Papadas, I. T.; Enotiadis, A.; Gengler, R. Y. N.; Gournis, D.; Rudolf, P.; Deligiannakis, Y.

    2009-01-01

    Fundamental properties such as cation exchange capacity (CEC), permanent charge, pH(PZC), and metal uptake of a Zn-containing montmorillonite are modified, in a predictable manner, by a mild chemical treatment using acetate. Acetate treatment allows a controllable increase of the CEC of montmorillon

  13. Fast detection of oxygen by the naked eye using a stable metal-organic framework containing methyl viologen cations.

    Science.gov (United States)

    Gong, Yun-Nan; Lu, Tong-Bu

    2013-09-11

    A stable porous metal-organic framework (MOF) containing methyl viologen cations exhibits reversible photochromic, thermochromic and fluorescence changes via host-guest interactions, and can be used for fast and selective detection of oxygen by naked eye recognition of color change within five seconds. PMID:23877538

  14. Identification of a crucial histidine involved in metal transport activity in the Arabidopsis cation/H(+) exchanger CAX1

    Science.gov (United States)

    In plants, yeast and bacteria, cation/H(+) exchangers (CAXs), have been shown to translocate Ca(2+) and other metals. The best characterized of these related transporters is the plant vacuolar-localized CAX1. We used site-directed mutagenesis to assess the impact of altering the seven histidine re...

  15. Effects of cation on electrical responses of ionic polymer-metal composite sensors at various ambient humidities

    Science.gov (United States)

    Zhu, Zicai; Horiuchi, Tetsuya; Takagi, Kentaro; Takeda, Jun; Chang, Longfei; Asaka, Kinji

    2016-08-01

    In this study, we investigated the effects of various cations on the electrical responses of ionic polymer-metal composite (IPMC) sensors at various ambient humidities. Four typical Au-Nafion IPMC samples were prepared with H+, Li+, Na+, and K+ cations. The voltage and current responses of the IPMCs were investigated under static and dynamic bending displacements. The orders of the voltage and current amplitudes were generally Li+ > Na+ > K+ > H+ and depended on the cation transport properties and the water content. The static voltage response first increased to a peak and then slowly decreased to a steady state. A negative steady-state voltage was initially observed for the IPMC with H+ cations under near saturation conditions. The voltage amplitude increased monotonously with increasing frequency from 0.1 to 10 Hz at a high relative humidity (RH, ˜90%), first increased and then decreased at moderate humidity (RH, ˜50%), and decreased continuously at low humidity (RH, ˜20%). The static current response first rapidly increased to a peak and then quickly decayed. During current decay, free oscillation decay occurred at high humidity and attenuated with decreasing humidity. This was confirmed to be the result of cation movement in the IPMC. There are three necessary conditions for oscillation: sufficient migrated cations, high cation mobility, and high stiffness of the polymer network. For the dynamic current response, the amplitude increased with increasing frequency (0.1-10 Hz) and showed good linearity. The underlying physics, mainly involving cation forward migration and back diffusion caused by mechano-chemo-electrical coupling, was clarified.

  16. Preparation of decarboxylic-functionalized weak cation exchanger and application for simultaneous separation of alkali, alkaline earth and transition metals.

    Science.gov (United States)

    Peng, Yahui; Gan, Yihui; He, Chengxia; Yang, Bingcheng; Guo, Zhimou; Liang, Xinmiao

    2016-06-01

    A novel weak cation exchanger (WCX) with dicarboxyl groups functionalized has been developed by clicking mercaptosuccinic acid onto silica gel. The simple synthesis starts with modification of silica gel with triethoxyvinylsilane, followed by efficient coupling vinyl-bonded silica with mercaptosuccinic acid via a "thiol-ene" click reaction. The obtained WCX demonstrated good separation and high selectivity towards common metals. Simultaneous separation of 10 alkali, alkaline earth and transition metals was achieved within 12min. Ion exchange and complex mechanism dominates the separation process. Its utility was demonstrated for determination of metals in tap water. PMID:27130093

  17. Surface and antitumor activity of some novel metal-based cationic surfactants

    Directory of Open Access Journals (Sweden)

    Badawi A

    2007-01-01

    Full Text Available The development of anticancer metal-based drugs was attempted by reacting dodecyl amine with selenious acid to produce a quaternary ammonium salt which was then converted to copper and cobalt cationic complexes via complexing the first compounds with copper (II or cobalt (II ions. The surface properties of these surfactants were investigated. The surface properties studied included critical micelle concentration (CMC, maximum surface excess (Γmax , and minimum surface area (Amin . Free energy of micellization (∆G o mic and adsorption (∆Go ads were calculated. Antitumor activity was tested by using Ehrlich ascites carcinoma (EAC as a model system of mice cell tumor. The compounds were also tested in vitro on five human monolayer tumor cell lines: MCF 7 (breast carcinoma, HEPG 2 (liver carcinoma, U 251 (brain tumor, HCT116 (colon carcinoma, and H460 (lung carcinoma. FTIR spectra, elemental analysis, and H 1 NMR spectra were performed to insure the purity of the prepared compounds.

  18. Synthesis of calix(aza)crown and its oligomeric analogue for the extraction of selected metal cations and dichromate anions

    Energy Technology Data Exchange (ETDEWEB)

    Akkus, Guelderen Uysal [Department of Chemistry, Afyon Kocatepe University, Afyonkarahisar (Turkey); Memon, Shahabuddin [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro (Pakistan); Sezgin, Mehmet; Yilmaz, Mustafa [Department of Chemistry, Selcuk University, Konya (Turkey)

    2009-02-15

    The present study reports the synthesis of a novel ionophore, calix[4]azacrown (5) bearing two amino groups at the lower rim along with its oligomeric analogue (6). The liquid-liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that (5) and (6) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species (5) shows remarkable extraction properties at low pH, whereas species (6) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  20. Solid-State Properties of One-Dimensional Metals Based on bis(oxalato)platinate Anions with Divalent Cations

    DEFF Research Database (Denmark)

    Braude, A.; Carneiro, K.; Jacobsen, Claus Schelde;

    1987-01-01

    The crystal structures, superstructures, dc conductivity, optical properties, and thermopower of six linear-chain conductors of the type M0.8[Pt(C2O4)2]⋅(M=Ni,Co,Zn,Fe,Mg,Mn), where M is a divalent metal (M=Ni,Co,Zn,Fe,Mg,Mn), have been studied. At high temperatures they form a common orthorhombic...... metallic phase (I) with conductivities of 30–200 (Ω cm)-1 and thermopowers of 5–10 μV/K, with the lattice weakly modulated by the one-dimensional Peierls distortion. Below T1, three compounds (Ni,Co,Zn) form a semiconducting phase (A-II) due to the ordering of the [M(H2O)6]+2 cations. As the cation...

  1. Network diversity through decoration of trigonal-prismatic nodes: Two-step crystal engineering of cationic metal-organic materials

    KAUST Repository

    Schoedel, Alexander

    2011-10-05

    MOMs the word! In a two-step process, first a trigonal-prismatic Primary Molecular Building Block ([Cr3O(isonic)6]+, tp-PMBB-1) was formed and then it was connected to linear linkers or square-planar nodes to afford three novel highly charged cationic metal-organic materials (MOMs) with snx, snw, and stp topologies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Liquid membrane extraction techniques for trace metal analysis and speciation in environmental and biological matrices

    Energy Technology Data Exchange (ETDEWEB)

    Ndungu, Kuria

    1999-04-01

    In this thesis, liquid-membrane-based methods for the analysis of trace metal species in samples of environmental and biological origin were developed. By incorporating extracting reagents in the membrane liquid, trace metal ions were selectively separated from humic-rich natural waters and urine samples, prior to their determination using various instrumental techniques. The extractions were performed in closed flow systems thus allowing easy automation of both the sample clean-up and enrichment. An acidic organophosphorus reagent (DEHPA) and a basic tetraalkylammonium reagent (Aliquat-336) were used as extractants in the membrane liquid to selectively extract and enrich cationic and anionic metal species respectively. A speciation method for chromium species was developed that allowed the determination of cationic Cr(III) species and anionic CR(VI) species in natural water samples without the need of a chromatographic separation step prior to their detection. SLM was also coupled on-line to potentiometric stripping analysis providing a fast and sensitive method for analysis of Pb in urine samples. A microporous membrane liquid-liquid extraction (MMLLE) method was developed for the determination of organotin compounds in natural waters that reduced the number of manual steps involved in the LLE of organotin compounds prior to their CC separation. Clean extracts obtained after running unfiltered humic-rich river water samples through the MMLLE flow system allowed selective determination of all the organotin compounds in a single run using GC-MS in the selected ion monitoring mode (SIM) 171 refs, 9 figs, 4 tabs

  3. NMR Structure and CD Titration with Metal Cations of Human Prion α2-Helix-Related Peptides

    Directory of Open Access Journals (Sweden)

    Luisa Ronga

    2007-01-01

    Full Text Available The 173–195 segment corresponding to the helix 2 of the C-globular prion protein domain could be one of several “spots” of intrinsic conformational flexibility. In fact, it possesses chameleon conformational behaviour and gathers several disease-associated point mutations. We have performed spectroscopic studies on the wild-type fragment 173–195 and on its D178N mutant dissolved in trifluoroethanol to mimic the in vivo system, both in the presence and in the absence of metal cations. NMR data showed that the structure of the D178N mutant is characterized by two short helices separated by a kink, whereas the wild-type peptide is fully helical. Both peptides retained these structural organizations, as monitored by CD, in the presence of metal cations. NMR spectra were however not in favour of the formation of definite ion-peptide complexes. This agrees with previous evidence that other regions of the prion protein are likely the natural target of metal cation binding.

  4. Synthesis and Structural Characterization of Complexes of a DO3A-Conjugated Triphenylphosphonium Cation with Diagnostically Important Metal Ions

    OpenAIRE

    Yang, Chang-Tong; Li, Yongxin; Liu, Shuang

    2007-01-01

    To understand the coordination chemistry of a DO3A-conjugated triphenylphosphonium (TPP) cation, triphenyl(4-((4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)methyl)benzyl)phosphonium (DO3A-xy-TPP), with diagnostically important metal ions, In(DO3A-xy-TPP)+, Ga(DO3A-xy-TPP)+ and Mn(DO3A-xy-TPP) were prepared by reacting DO3A-xy-TPP with one equivalent of the respective metal salt. All three complexes have been characterized by elemental analysis, IR, ESI-MS, NMR methods for In(...

  5. Acceptable levels of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in soils, depending on their clay and humus content and cation-exchange capacity

    NARCIS (Netherlands)

    Haan, de S.; Rethfeld, H.; Driel, van W.

    1985-01-01

    Three sandy soils differing in humus content and three clay soils differing in clay content were supplied with heavy metals to determine which loading rate of each single metal should be regarded as critical from the viewpoint of crop yield and metal content dependent on soil cation exchange capacit

  6. Biological metals and Alzheimer's disease: implications for therapeutics and diagnostics.

    Science.gov (United States)

    Duce, James A; Bush, Ashley I

    2010-09-01

    The equilibrium of metal ions is critical for many physiological functions, particularly in the central nervous system, where metals are essential for development and maintenance of enzymatic activities, mitochondrial function, myelination, neurotransmission as well as learning and memory. Due to their importance, cells have evolved complex machinery for controlling metal-ion homeostasis. However, disruption of these mechanisms, or absorption of detrimental metals with no known biological function, alter the ionic balance and can result in a disease state, including several neurodegenerative disorders such as Alzheimer's disease. Understanding the complex structural and functional interactions of metal ions with the various intracellular and extracellular components of the central nervous system, under normal conditions and during neurodegeneration, is essential for the development of effective therapies. Accordingly, assisting the balance of metal ions back to homeostatic levels has been proposed as a disease-modifying therapeutic strategy for Alzheimer's disease as well as other neurodegenerative diseases.

  7. Density functional theory study of interaction, bonding and affinity of group IIb transition metal cations with nucleic acid bases

    Science.gov (United States)

    Bagchi, Sabyasachi; Mandal, Debasish; Ghosh, Deepanwita; Das, Abhijit K.

    2012-05-01

    The structure, bonding, and energetics of the complexes obtained from the interaction between the most stable tautomeric forms of free DNA and RNA bases and Zn2+, Cd2+ and Hg2+ cations have been studied using density functional B3LYP method. The 6-311+G (2df, 2p) basis set along with LANL2DZ pseudopotentials for the cations are used in the calculations. The tautomerization paths of the nucleobases are investigated and transition states between the tautomeric forms of the free bases are located. The relative stability of the complexes and the tautomers of the free nucleobases are discussed referring to MIA and relative energy values. For uracil, thymine and adenine, interaction of the metal cations with the most stable tautomers form the least stable molecular complexes. For cytosine and guanine, the stability of the metalated complexes differs significantly. The enthalpy (ΔH), entropy (TΔS) and free energy (ΔG) of the complexes at 298 K have also been calculated.

  8. Role of serum eosinophil cationic protein as a biological marker to assess the severity of bronchial asthma

    International Nuclear Information System (INIS)

    Objective: The study was carried out to evaluate the role of serum eosinophil cationic protein (ECP) as a biological marker for the diagnosis and to assess the severity of bronchial asthma. Methodology: This observational cross-sectional study was conducted among 70 bronchial asthma patients and 45 disease controls (tuberculosis-15, chronic obstructive pulmonary disease-15, interstitial lung disease-15) enrolled from patients attending the outpatient department of the National Institute of Disease of the Chest and Hospital (NIDCH), Dhaka, Bangladesh during July 2010 to June 2011. Global Initiative of Asthma Management and Prevention (GINA) criteria were followed for selection of both atopic and non-atopic patients with intermittent or persistent (mild, moderate and severe) asthma. Serum level of eosinophil cationic protein (ECP), IgE, forced expiratory volume in 1 second (FEV 1% predicted) and circulatory eosinophil (CE) count were estimated. Results: Mean serum ECP level (28.8 +- 42.9 vs. 6.82 +- 3.5 ng/mL; P<0.001), IgE level (383.59 - 225.3 vs. 135 +- 131.8 IU/mL; P<0.001) and percent circulatory eosinophil count (9.95 +- 3.7 vs. 5.95 +- 1.4; P<0.024) were all found significantly raised among asthma patients than disease controls but % FEV1 was equivocal. All grades of persistent asthma patients had significantly (P<0.025 and P<0.002) higher mean ECP level than intermittent cases but serum IgE level and CE count did not differ significantly. FEV1 % predicted correlated well among moderate and severe persistent asthma but was equivocal for intermittent and mild persistent cases. Conclusion: This study has reinforced that serum eosinophil cationic protein is a dependable biological marker with more discriminatory power over other indicators for bronchial asthma and to assess its severity. (author)

  9. Rational design of carbonitrile-carboxaldehyde cation receptor models: probing the nature of the heteroatom-metal interaction.

    Science.gov (United States)

    Rosli, Ahmad Nazmi; Abu Bakar, Maizathul Akmam; Lee, Vannajan Sanghiran; Zain, Sharifuddin Md; Ahmad, Mohd Rais; Abdul Manan, Ninie Suhana; Alias, Yatimah; Woi, Pei Meng

    2014-09-01

    In this work, hybrid functional and G4 methods were employed in the rational design of carbonitrile-carboxaldehyde receptor models for cation recognition. Electron-sharing and ionic interactions between the models and the cations were analyzed utilizing the concepts of overlap population, atomic valence, electrostatic potential, and CHELPG charge in order to elucidate the nature of the heteroatom-metal interaction, the N versus O disparity, and the effect of pH. Receptor fragment models from ionomycin were employed to rationalize the selection of receptor models for discriminating group I cations and enhancing the selectivity for Mg(II) rather than Ca(II), and to examine the effects of keto-enol forms and negatively charged sites. The changes in geometries, overlap population, metal valence, and CHELPG charge upon solvation in heptane medium as compared to the gas phase were negligible. The optimized geometries reveal that the interaction between group II cations and the keto, enol, and enolate forms of 2-cyanoethanal causes 12 % bending of the C-C-N angle from linearity. Overlap populations show that the electron-sharing interaction favors group II cations but that the same mechanism allows Li(I) to compete. The total spin of Li(I) is 17 % greater than that of Ca(II), but the G4 binding energies of the two are separated by more than 50 kcal/mol, favoring group II cations, which may eliminate interference from Li(I). 1,2-Dicyanoethylene, which has only one form, shows similar characteristics. CHELPG analysis shows that Mg(II) transfers 25 and 18 % of its positive charge to 2-cyanoethanal enolate and 1,2-dicyanoethylene, respectively. Hydrogen atoms receive most of the positive charge in both receptors, but the N-termini exhibit strikingly different characteristics. Electrostatic potential contour profiles were found to be in good agreement with the atomic charge distributions. The application of uncharged 1,3-dicarbonyl and 2-cyanocarbonyl receptors and a judicious

  10. MetalPDB: a database of metal sites in biological macromolecular structures

    OpenAIRE

    C. Andreini; Cavallaro, G.; Lorenzini, S.; Rosato, A.

    2013-01-01

    We present here MetalPDB (freely accessible at http://metalweb.cerm.unifi.it), a novel resource aimed at conveying the information available on the three-dimensional (3D) structures of metal-binding biological macromolecules in a consistent and effective manner. This is achieved through the systematic and automated representation of metal-binding sites in proteins and nucleic acids by way of Minimal Functional Sites (MFSs). MFSs are 3D templates that describe the local environment around the ...

  11. Complex formation in the system double charged metal cation-Stenhouse base in water-alcohol solution

    International Nuclear Information System (INIS)

    Using the method of potentiometric titration complex formation reaction of the system metal(II) salt cation (Me2+ = Fe2+, Cd2+, Hg2+, Zn2+, Mn2+, Co2+, Ni2+) Stenhouse base in water-alcohol solution has been studied. Compositions of equilibrium complexes, the constants of their formation and instability have been determined. CoCl2 x 6H2O, NiCl2 x 6H2O and Mn(NO3)2 x 6H2O have been shown to have the most stabilizing effect on Stenhouse base

  12. Correction to the Metal-Insulator Transition Temperature due to Cation Size and Strain Effects for Colossal Magnetoresistance Perovskites

    Institute of Scientific and Technical Information of China (English)

    袁松柳; 刘洁; 夏正才; 彭刚; 唐洁; 张国宏; 张力江; 冯文; 李衷怡; 杨应平; 刘莉; 熊曹水

    2002-01-01

    A phenomenological expression of the metal-insulator transition temperature is proposed for AMnO3 manganese perovskites by taking into account the distortion of the Mn-O-Mn bond due to A-cation size and the straindependent effect due to performed Jahn-Teller distortions, independently. Using reasonable physical parameters,the calculated results give excellent agreement with experimental data obtained in polycrystalline samples of La2/3 (Ca1-xBax)1/3MnO3, providing a strong support to this approach.

  13. Alkali metal cation complexation and solvent interactions by robust chromium(III) fluoride complexes

    DEFF Research Database (Denmark)

    Birk, T.; Magnussen, M.J.; Piligkos, Stergios;

    2010-01-01

    Interaction of robust chromium(III) fluoride complexes with sodium or lithium cations in solution lead to hypsochromic spectral shifts of increasing magnitude along the series: trans-[CrF2(py)(4)](+), mer-[CrF3(terpy)], and fac-[CrF3(Me(3)tacn)]. Crystalline products isolated from solution exhibi...

  14. Effects of Octylphenol and Bisphenol A on the Metal Cation Transporter Channels of Mouse Placentas

    Science.gov (United States)

    Lee, Jae-Hwan; Ahn, Changhwan; Kang, Hee Young; Hong, Eui-Ju; Hyun, Sang-Hwan; Choi, Kyung-Chul; Jeung, Eui-Bae

    2016-01-01

    Octylphenol (OP) and bisphenol A (BPA) are known as endocrine-disrupting chemicals (EDCs). During pregnancy, the expression of steroid hormone receptors is controlled by maternal and fetal nutrition. To evaluate the impact of EDCs during pregnancy, ethinyl estradiol (EE, 0.2 mg/kg/day), OP (50 mg/kg/day), and BPA (50 mg/kg/day) were administered to pregnant mice. The mRNA levels of TRPV6 (transient receptor potential cation channels in subfamily V, member 6) decreased significantly by EE and OP. The PMCA1 (ATPase, Ca++ transporting, plasma membrane 1) mRNA and protein levels decreased significantly by EE, OP, and BPA. CTR1 (solute carrier family 31, member 1) and ATP7A (ATPase, Cu++ transporting, alpha polypeptide) expression decreased significantly by EE, OP, and BPA. The mRNA levels of IREG1 (iron-regulated transporter, member 1) decreased significantly by EE. Hephaestin (HEPH) mRNA levels decreased significantly by EE, OP, and BPA, and protein levels decreased significantly by BPA. As a result of immunohistochemistry analysis, all cation transporter proteins were found in labyrinth of placenta. To confirm the cytosolic level of cations, levels of cation level in fetal serum were measured. EE, OP, and BPA significantly reduced serum calcium and copper levels, and iron levels were reduced by BPA. Taken together, some EDCs, such as OP and BPA, could modulate the calcium, copper, and iron ion-transporting channels during pregnancy. The fetus relies on the mother for ionic transportation, and, therefore, pregnant women should avoid exposure to cation-channel-disrupting chemicals. PMID:27690074

  15. Effects of Octylphenol and Bisphenol A on the Metal Cation Transporter Channels of Mouse Placentas

    Directory of Open Access Journals (Sweden)

    Jae-Hwan Lee

    2016-09-01

    Full Text Available Octylphenol (OP and bisphenol A (BPA are known as endocrine-disrupting chemicals (EDCs. During pregnancy, the expression of steroid hormone receptors is controlled by maternal and fetal nutrition. To evaluate the impact of EDCs during pregnancy, ethinyl estradiol (EE, 0.2 mg/kg/day, OP (50 mg/kg/day, and BPA (50 mg/kg/day were administered to pregnant mice. The mRNA levels of TRPV6 (transient receptor potential cation channels in subfamily V, member 6 decreased significantly by EE and OP. The PMCA1 (ATPase, Ca++ transporting, plasma membrane 1 mRNA and protein levels decreased significantly by EE, OP, and BPA. CTR1 (solute carrier family 31, member 1 and ATP7A (ATPase, Cu++ transporting, alpha polypeptide expression decreased significantly by EE, OP, and BPA. The mRNA levels of IREG1 (iron-regulated transporter, member 1 decreased significantly by EE. Hephaestin (HEPH mRNA levels decreased significantly by EE, OP, and BPA, and protein levels decreased significantly by BPA. As a result of immunohistochemistry analysis, all cation transporter proteins were found in labyrinth of placenta. To confirm the cytosolic level of cations, levels of cation level in fetal serum were measured. EE, OP, and BPA significantly reduced serum calcium and copper levels, and iron levels were reduced by BPA. Taken together, some EDCs, such as OP and BPA, could modulate the calcium, copper, and iron ion-transporting channels during pregnancy. The fetus relies on the mother for ionic transportation, and, therefore, pregnant women should avoid exposure to cation-channel-disrupting chemicals.

  16. Metal release from stainless steel in biological environments: A review.

    Science.gov (United States)

    Hedberg, Yolanda S; Odnevall Wallinder, Inger

    2016-03-01

    Due to its beneficial corrosion resistance, stainless steel is widely used in, e.g., biomedical applications, as surfaces in food contact, and for products intended to come into skin contact. Low levels of metals can be released from the stainless steel surface into solution, even for these highly corrosion resistant alloys. This needs to be considered in risk assessment and management. This review aims to compile the different metal release mechanisms that are relevant for stainless steel when used in different biological settings. These mechanisms include corrosion-induced metal release, dissolution of the surface oxide, friction-induced metal release, and their combinations. The influence of important physicochemical surface properties, different organic species and proteins in solution, and of biofilm formation on corrosion-induced metal release is discussed. Chemical and electrochemical dissolution mechanisms of the surface oxides of stainless steel are presented with a focus on protonation, complexation/ligand-induced dissolution, and reductive dissolution by applying a perspective on surface adsorption of complexing or reducing ligands and proteins. The influence of alloy composition, microstructure, route of manufacture, and surface finish on the metal release process is furthermore discussed as well as the chemical speciation of released metals. Typical metal release patterns are summarized. PMID:26514345

  17. Introduction of a cation in aqueous solution by electrolytic dissolution of metal. Applications to the decontamination of radioactive effluents

    International Nuclear Information System (INIS)

    This research thesis aims at comparing results obtained in chemical decontamination of radioactive effluents with a metallic cation introduced by metal electro-dissolution or by dose addition. After an overview of methods used for the purification of radioactive effluents and a more precise presentation of chemical co-precipitation, the author reports preliminary tests of the application of chemical co-precipitation to the decontamination of radioactive effluents, reports the analysis of iron, zinc and copper behaviour in aqueous environment by means of thermodynamic diagrams and current-voltage curves. He reports the design and use of two electro-dissolution sets, and the application of copper electrolytic dissolution to the elimination of ruthenium in radioactive effluents. He finally addresses the purification treatment of effluents of nuclear reactors

  18. Properties of solvated electrons, alkali anions and other species in metal solutions and kinetics of cation and electron exchange reactions. Final report

    International Nuclear Information System (INIS)

    The properties of solutions of alkali metals in amine solvents were studied by optical, ETR, NMR and electrochemical methods. Complexation of the alkali cations by crown ethers and cryptands permitted the preparation of concentrated solutions of alkali metals in amine and ether solvents. Extensive alkali metal NMR studies of the exchange of M+ with crown-ethers and cryptands and of the alkali metal anion, M-, were made. The first crystalline salt of an alkali metal anion, Na+ Cryptand [2.2.2]Na- was synthesized and characterized and led to the preparation of other alkali metal anion salts. This research provided the foundation for continuing studies of crystalline alkalide salts

  19. Full factorial design, physicochemical characterisation and biological assessment of cyclosporine A loaded cationic nanoparticles.

    Science.gov (United States)

    Hermans, Kris; Van den Plas, Dave; Everaert, Arnout; Weyenberg, Wim; Ludwig, Annick

    2012-09-01

    Cyclosporine A loaded poly(lactide-co-glycolide) nanoparticles coated with chitosan were prepared using the o/w emulsification solvent evaporation method. A 2(3) full factorial design was used to investigate the effect of 3 preparation parameters on the particle size, polydispersity index, zeta potential and drug release. In vitro experiments were performed in order to evaluate the cytotoxicity and anti-inflammatory activity of the developed nanoparticles. Particle sizes varied from 156 nm to 314 nm, and polydispersity index values of 0.07-0.56 were obtained depending on the different preparation parameters. All nanoparticles showed positive zeta potential values. Nanoparticles prepared with the highest concentration chitosan retained a positive zeta potential after dispersion in simulated lachrymal fluid, which supports the possibility of an electrostatic interaction between these particles and the negatively charged mucus layer at the eye. The in vitro release profile of cyclosporine A from the chitosan-coated nanoparticles was strongly dependent on the release medium used. None of the cationic nanoparticle formulations showed significant cytotoxicity compared to the negative control using human epithelial cells (HaCaT). Cyclosporine A encapsulated in the various nanoparticle formulations remained anti-inflammatory active as significant suppression of interleukine-2 secretion in concanavalin A stimulated Jurkat T cells was observed.

  20. Influence of alkali metal cations on the thermal, mechanical and morphological properties of rectorite/chitosan bio-nanocomposite films.

    Science.gov (United States)

    Babul Reddy, A; Jayaramudu, J; Siva Mohan Reddy, G; Manjula, B; Sadiku, E R

    2015-05-20

    The main theme of this work is to study the influence of ion-exchangeable alkali metal cations, such as: Li(+), Na(+), K(+), and Cs(+) on the thermal, mechanical and morphological properties. In this regard, a set of rectorite/chitosan (REC-CS) bio-nanocomposite films (BNCFs) was prepared by facile reaction of chitosan with ion-exchanged REC clay. The microstructure and morphology of BNCFs were investigated with XRD, TEM, SEM and AFM. Thermal and tensile properties of BNCFs were also investigated. As revealed from TEM and XRD results, the BNCFs featured a mixed morphology. Some intercalated clay sheets, together with nano-sized clay tactoids were obtained in LiREC/CS, NaREC/CS and KREC/CS of the BNCFs. From fractured surface study, via SEM, it was observed that the dispersion of chitosan polymer attaches to (and covers) the clay platelets. FTIR confirmed strong hydrogen bonds between clay and chitosan polymer. In addition, the thermal stabilities significantly varied when alkali metal cations varied from Li(+) to Cs(+). The BNCFs featured high tensile strengths (up to 84 MPa) and tensile moduli (up to 45 GPa). After evaluating these properties of BNCFs, we came to conclusion that these bio-nano composites can be used for packaging applications.

  1. Effects of Anions and Cations on π-Complexation Between Olefin and Metal Halide

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jin-xia; ZHANG Yong-chun; GUO Xin-wen

    2005-01-01

    An ab initio molecular orbital study was performed to determine the effects of anions and cations on the π-complexation of C2H4 on MX(M=Ag, Cu; X=F, Cl). The calculated results show the following order of adsorption strength: F->Cl- for anions; Cu+>Ag+ for cations. The results can be explained by the detailed analysis of atomic charge, orbital energy and orbital population by using the natural bond orbital(NBO) theory: (1) anions with stronger electronegativity can attract more electrons from the s orbital of M, while at the same time it does not obviously weaken the d orbital occupation of M, thus the nearly vacant s orbital and the sufficiently filled d orbitals of M help with forming σ-donation and d-π* backdonation with the π orbital and the π* orbital of olefin, respectively; (2) a smaller energy gap of symmetry-adapted orbitals between olefin and a cation can favor the electron transfer, that is why Cu+ forms stronger adsorption with olefin than Ag+does.

  2. Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

    Directory of Open Access Journals (Sweden)

    Awatef Ayadi

    2015-08-01

    Full Text Available The synthesis and full characterization of two tetrathiafulvalene-appended azine ligands, namely 2-([2,2’-bi(1,3-dithiolylidene]-4-yl-6-((2,4-dinitrophenylhydrazonomethylpyridine (L1 and 5-([2,2’-bi(1,3-dithiolylidene]-4-yl-2-((2,4-dinitrophenylhydrazonomethylpyridine (L2 are described. The crystal structure of ligand L1 indicates that the ligand is completely planar with the presence of a strong intramolecular N3–H3···O1 hydrogen bonding. Titration experiments with inorganic anions showed that both ligands are suitable candidates for the sensing of fluoride anions. Ligand L2 was reacted with a Re(I cation to yield the corresponding rhenium tricarbonyl complex 3. In the crystal structure of the newly prepared electroactive rhenium complex the TTF is neutral and the rhenium cation is hexacoordinated. The electrochemical behavior of the three compounds indicates that they are promising for the construction of crystalline radical cation salts.

  3. Biotic ligand modeling approach: Synthesis of the effect of major cations on the toxicity of metals to soil and aquatic organisms.

    Science.gov (United States)

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

    2015-10-01

    The biotic ligand model (BLM) approach is used to assess metal toxicity, taking into account the competition of other cations with the free metal ions for binding to the biotic ligand sites of aquatic and soil organisms. The bioavailable fraction of metals, represented by the free metal ion, is a better measure than the total concentration for assessing their potential risk to the environment. Because BLMs are relating toxicity to the fraction of biotic ligands occupied by the metal, they can be useful for investigating factors affecting metal bioaccumulation and toxicity. In the present review, the effects of major cations on the toxicity of metals to soil and aquatic organisms were comprehensively studied by performing a meta-analysis of BLM literature data. Interactions at the binding sites were shown to be species- and metal-specific. The main factors affecting the relationships between toxicity and conditional binding constants for metal binding at the biotic ligand appeared to be Ca(2+) , Mg(2+) , and protons. Other important characteristics of the exposure medium, such as levels of dissolved organic carbon and concentrations of other cations, should also be considered to obtain a proper assessment of metal toxicity to soil and aquatic organisms.

  4. The sorption of some heavy metal cations using A and P zeolites, synthesized from Iranian natural clinoptilolite and investigation of ionic interference effects on sorption

    International Nuclear Information System (INIS)

    Heavy metal cations exist in the industrial waste streams,fi.om factories and mines. Most of them are very toxic and harmful to human kind and its environment. In this research, removal of some cations from a simulated waste stream was investigated. Most of researches were investigated the removal of cations without presence of other cations. This paper intends to investigate the effect of the ionic interference on the heavy cations removal with synthetic zeolites A and P, which were synthesized from Iranian natural clinoptilolite. In this concern, effects of various parameters such as reaction time, temperature, and pH, concentration of the in going heavy metal cations (i.e. Pb2+, Zn2+, Cd2+ and Ni2+ ) as well as the effect of ionic interference were investigated. The results obtained from batch and column operations were shown that it is possible to reduce the concentration of these cations to an acceptable level based on the environmental standards, by using these zeolites

  5. Spectroscopic and theoretical investigations of vibrational frequencies in binary unsaturated transition-metal carbonyl cations, neutrals, and anions.

    Science.gov (United States)

    Zhou, M; Andrews, L; Bauschlicher, C W

    2001-07-01

    Figure 18 presents the C-O stretching vibrational frequencies of the first-row transition-metal monocarbonyl cations, neutrals, and anions in solid neon; similar diagrams have been reported for neutral MCO species in solid argon, but three of the early assignments have been changed by recent work and one new assignment added. The laser-ablation method produces mostly neutral atoms with a few percent cations and electrons for capture to make anions; in contrast, thermal evaporation gives only neutral species. Hence, the very recent neon matrix investigations in our laboratory provide carbonyl cations and anions for comparison to neutrals on a level playing field. Several trends are very interesting. First, for all metals, the C-O stretching frequencies follow the order cations > neutrals > anions with large diagnostic 100-200 cm-1 separations, which is consistent with the magnitude of the metal d to CO pi * donation. Second, for a given charge, there is a general increase in C-O stretching vibrational frequencies with increasing metal atomic number, which demonstrates the expected decrease in the metal to CO pi * donation with increasing metal ionization potential. Some of the structure in this plot arises from the extra stability of the filled and half-filled d shell and from the electron pairing that occurs at the middle of the TM row; the plot resembles the "double-humped" graph found for the variation in properties across a row of transition metals. For the anions, the variation with metal atom is the smallest since all of the metals can easily donate charge to the CO ligand. Third, for the early transition-metal Ti, V, and Cr families, the C-O stretching frequencies decrease when going down the family, but the reverse relationship is observed for the late transition-metal Fe, Co, and Ni families. In most of the present discussion, we have referred to neon matrix frequencies; however, the argon matrix frequencies are complementary, and useful information can be

  6. Alkali Metal Ion Complexes with Phosphates, Nucleotides, Amino Acids, and Related Ligands of Biological Relevance. Their Properties in Solution.

    Science.gov (United States)

    Crea, Francesco; De Stefano, Concetta; Foti, Claudia; Lando, Gabriele; Milea, Demetrio; Sammartano, Silvio

    2016-01-01

    Alkali metal ions play very important roles in all biological systems, some of them are essential for life. Their concentration depends on several physiological factors and is very variable. For example, sodium concentrations in human fluids vary from quite low (e.g., 8.2 mmol dm(-3) in mature maternal milk) to high values (0.14 mol dm(-3) in blood plasma). While many data on the concentration of Na(+) and K(+) in various fluids are available, the information on other alkali metal cations is scarce. Since many vital functions depend on the network of interactions occurring in various biofluids, this chapter reviews their complex formation with phosphates, nucleotides, amino acids, and related ligands of biological relevance. Literature data on this topic are quite rare if compared to other cations. Generally, the stability of alkali metal ion complexes of organic and inorganic ligands is rather low (usually log K  Na(+) > K(+) > Rb(+) > Cs(+). For example, for citrate it is: log K ML = 0.88, 0.80, 0.48, 0.38, and 0.13 at 25 °C and infinite dilution. Some considerations are made on the main aspects related to the difficulties in the determination of weak complexes. The importance of the alkali metal ion complexes was also studied in the light of modelling natural fluids and in the use of these cations as probes for different processes. Some empirical relationships are proposed for the dependence of the stability constants of Na(+) complexes on the ligand charge, as well as for correlations among log K values of NaL, KL or LiL species (L = generic ligand). PMID:26860301

  7. Influence of soil properties on heavy metal sequestration by biochar amendment: 1. Copper sorption isotherms and the release of cations.

    Science.gov (United States)

    Uchimiya, Minori; Klasson, K Thomas; Wartelle, Lynda H; Lima, Isabel M

    2011-03-01

    The amendment of carbonaceous materials such as biochars and activated carbons is a promising in situ remediation strategy for both organic and inorganic contaminants in soils and sediments. Mechanistic understandings in sorption of heavy metals on amended soil are necessary for appropriate selection and application of carbonaceous materials for heavy metal sequestration in specific soil types. In this study, copper sorption isotherms were obtained for soils having distinct characteristics: clay-rich, alkaline San Joaquin soil with significant heavy metal sorption capacity, and eroded, acidic Norfolk sandy loam soil having low capacity to retain copper. The amendment of acidic pecan shell-derived activated carbon and basic broiler litter biochar lead to a greater enhancement of copper sorption in Norfolk soil than in San Joaquin soil. In Norfolk soil, the amendment of acidic activated carbon enhanced copper sorption primarily via cation exchange mechanism, i.e., release of proton, calcium, and aluminum, while acid dissolution of aluminum cannot be ruled out. For San Joaquin soil, enhanced copper retention by biochar amendment likely resulted from the following additional mechanisms: electrostatic interactions between copper and negatively charged soil and biochar surfaces, sorption on mineral (ash) components, complexation of copper by surface functional groups and delocalized π electrons of carbonaceous materials, and precipitation. Influence of biochar on the release of additional elements (e.g., Al, Ca) must be carefully considered when used as a soil amendment to sequester heavy metals. PMID:21147495

  8. Effects of humic acid and competing cations on metal uptake by Lolium perenne

    NARCIS (Netherlands)

    Kalis, E.J.J.; Temminghoff, E.J.M.; Weng, L.P.; Riemsdijk, van W.H.

    2006-01-01

    Within the biotic ligand model, which describes relationships between chemical speciation and metal binding at an organism's surface, multicomponent (long-term) metal uptake by plants has seldom been studied. In the present work, we exposed perennial ryegrass to nutrient solutions with two levels of

  9. Selective adsorption of cationic dyes from aqueous solution by polyoxometalate-based metal-organic framework composite

    Science.gov (United States)

    Liu, Xiaoxia; Gong, Wenpeng; Luo, Jing; Zou, Chentao; Yang, Yun; Yang, Shuijin

    2016-01-01

    A novel environmental friendly adsorbent H6P2W18O62/MOF-5 was synthesized by a simple one-step reaction under solvothermal conditions and characterized by XRD, FTIR, thermogravimetric analyses (TGA) and N2 adsorption-desorption isotherms. The removal rate of H6P2W18O62/MOF-5 was quite greater (85%) than that of MOF-5 (almost zero), showing that the adsorption performance of porous MOF-5 can be improved through the modification of H6P2W18O62. Further study revealed that H6P2W18O62/MOF-5 exhibited a fast adsorption rate and selective adsorption ability towards the cationic dyes in aqueous solution. The removal rate was up to 97% for cationic dyes methylene blue (MB) and 68% for rhodamine B(Rhb) within 10 min. However, anionicdye methyl orange(MO) can only reach to 10%. The influences including initial concentration, contact time, initial solution pH and temperature of MB adsorption onto H6P2W18O62/MOF-5 were investigated in detail. The kinetic study indicated that the adsorption of MB onto H6P2W18O62/MOF-5 followed the pseudo second-order model well. The isotherm obtained from experimental data fitted the Langmuir model, yielding maximum adsorption capacity of 51.81 mg/g. The thermodynamic parameters analysis illustrated that the MB adsorption onto H6P2W18O62 immobilized MOF-5 was spontaneous and endothermic process. Besides, these results implied that designing a novel material polyoxometalate-based metal-organic frameworks is great potential for removing cationic organic pollutants and even extended to improve other specific application.

  10. Nano-baskets of Calix[4]-1,3-crown in Emulsion Membranes for Selective Extraction of Alkali Metal Cations

    Institute of Scientific and Technical Information of China (English)

    Bahram Mokhtari; Kobra Pourabdollah

    2013-01-01

    Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclu-sion-facilitated emulsion liquid membrane process. The novelty of this study is application of nano-baskets of calixcrown in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of diacid calix[4]-1,3-crowns-4,5 were synthesized, and their inclusion-extraction parameters were optimized including the calixcrown scaffold (4.4%, by mass) as the carrier/demulsifier, the commercial kero-sene as diluent in membrane, sulphonic acid (0.2 mol·L-1) and ammonium carbonate (0.4 mol·L-1) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed (300 r·min-1), and initial solute concen-tration (100 mg·L-1). The selectivity of membrane over more than ten interfering cations was examined and the re-sults reveled that under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98%-99%.

  11. Model based multi-wavelength spectrophotometric method for calculation of formation constants of phenanthrenequinone thiosemicarbazone complexes with some metallic cations

    Directory of Open Access Journals (Sweden)

    Naser Samadi

    2013-04-01

    Full Text Available In traditional spectrophotometric determination of stability constants of complexation, it is necessary to find a wavelength at which only one of the components has absorbance without any spectroscopic interference of the other reaction components. In the present work, a simple multi-wavelength model-based method has been developed to determine stability constants for complexation reaction regardless of the spectra overlapping of components. Also, pure spectra and concentration profiles of all components are extracted using multi-wavelength model based method. In the present work spectrophotometric titration of several cationic metal ions with new synthetic ligand were studied in order to calculate the formation constant(s. In order to estimate the formation constants a chemometrics method, model based analysis was applied.

  12. Morphology of sulfonated polyimide ionomers from ESR spectra of paramagnetic transition metal cations and nitroxide spin probes

    International Nuclear Information System (INIS)

    We present a study of sulfonated polyimide block ionomer membranes (SPIs) in the dry state, and swollen by water, methanol, ethanol, and dioxane. The ionomers are based on a naphthalenic dianhydride, and differ in the ionic exchange capacity and the type of diamine in the hydrophobic block. The ionomers were studied by electron spin resonance (ESR) spectroscopy of the paramagnetic transition metal cations Cu+ and VO2+, and of two nitroxide spin probes. The results indicated the existence of separate hydrophobic and hydrophilic domains in the dry and in the swollen membranes. Water clusters with a diameter + or K+. The irreversible increase of the signal intensity upon heating of the dry membranes above 360 K suggests the formation of reactive intermediates that may be involved in ionomer degradation processes. (author)

  13. Synthesis and Crystal Structure of A New Armed-tetraazacrown Ether and Its Liquid Membrane Transport of Alkali Metal Cations

    Institute of Scientific and Technical Information of China (English)

    马淑兰; 朱文祥; 董淑静; 郭倩玲; 佘远斌

    2003-01-01

    A new tetra-N-substituted tetraazacrown ether derivative, 4,7,13,16-tetra ( 2-cyanobenzyl)-1, 10-dioxa-4, 7, 13, 16-tetraazacy-dooctademne, C44H48N8O2, has been synthesized and struc-turally characterized. It crystallizes in the monoclinic system,Slmeegroup P21/c with a = 1.1176(3) nm, b =2.1906(7) nm,c=0.8430(3)nm, V=2.0132(10)nm3, β = 102.740(5)°,Z=4, Dc= 1.189 g/cm3, final R1=0.0460, wR2=0.0803.The liquid membrane transports of alkali metal cations using the new macrocyde as the ion-carrier were also studied. Com-pared with some macrocyclic ligands, our newly synthesized lig.and showed a good selectivity ratio for Na Na+/Li+.

  14. Electrophysical methods of separation of metal cations in the moving salts solution

    Science.gov (United States)

    Gofman, V. N.; Tuksov, I. V.; Timchenko, S. N.; Shamanin, I. V.; Poberezhnikov, A. D.; Kazaryan, M. A.

    2016-07-01

    The results of experiments on the excitation of the phenomenon of selective drift of solvated ions under the influence of an external "asymmetric" electric field to the circulating solution of calcium chloride and magnesium salts in a polar liquid dielectric - water are shown. The purpose of the experiments was to determine the influence of the field frequency and amplitude of the field strength on the excitation phenomenon, and the study of the operating characteristics of the testing apparatus - a dividing cell. The dependences of the separation efficiency of solvated cations from the frequency of the external field and the excitation threshold of the phenomenon from the field strength in the separation cell are defined.

  15. Metal cation sensing material based on the assembly of meso-terakis(4-N,N,N-trimethylamiophenyl) porphyrin and mesoporous molecular sieve MCM-41

    Institute of Scientific and Technical Information of China (English)

    ZHANG Huidong; SUN Yinghui; ZHANG Ping; YE Kaiqi; ZHANG Jingying; WANG Yue

    2005-01-01

    The metal cation sensing material was prepared by entrapment of a water-soluble porphyrin compound, mesoterakis(4-N,N,N-trimethylamiophenyl) porphyrin (TTMAPP), in mesoporous molecular sieve MCM-41. The powder X-ray diffraction (XRD) spectra results demonstrated that after the introduction of TTMAPP, the ordered channel arrangement of MCM-41 remained. The assembly material, TTMAPP/MCM-41, exhibited a typical absorption feature of porphyrin compound. Emission spectrum study revealed that the introduction of zinc (II) cation resulted in the formation of a new emission peak at 600 nm for TTMAPP/MCM-41, while the presence of copper (II) cation at low concentration led to that the luminescent intensity of TTMAPP/MCM-41 was obviously reduced by 68.42%. The experiment results demonstrated that TTMAPP/MCM-41 is a cation sensing materials with good performance.

  16. Cationic methyl complexes of the rare-earth metals: an experimental and computational study on synthesis, structure, and reactivity.

    Science.gov (United States)

    Kramer, Mathias U; Robert, Dominique; Arndt, Stefan; Zeimentz, Peter M; Spaniol, Thomas P; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Okuda, Jun

    2008-10-20

    Synthesis, structure, and reactivity of two families of rare-earth metal complexes containing discrete methyl cations [LnMe(2-x)(thf)n]((1+x)+) (x = 0, 1; thf = tetrahydrofuran) have been studied. As a synthetic equivalent for the elusive trimethyl complex [LnMe3], lithium methylates of the approximate composition [Li3LnMe6(thf)n] were prepared by treating rare-earth metal trichlorides [LnCl3(thf)n] with 6 equiv of methyllithium in diethyl ether. Heteronuclear complexes of the formula [Li3Ln2Me9L(n)] (Ln = Sc, Y, Tb; L = Et2O, thf) were isolated by crystallization from diethyl ether. Single crystal X-ray diffraction studies revealed a heterometallic aggregate of composition [Li3Ln2Me9(thf)n(Et2O)m] with a [LiLn2Me9](2-) core (Ln = Sc, Y, Tb). When tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = Y, Lu) was reacted with less than 1 equiv of [NR3H][BPh4], the dimethyl cations [LnMe2(thf)n][BPh4] were obtained. The coordination number as well as cis/trans isomer preference was studied by crystallographic and computational methods. Dicationic methyl complexes of the rare-earth metals of the formula [LnMe(thf)n][BAr4]2 (Ln = Sc, Y, La-Nd, Sm, Gd-Lu; Ar = Ph, C6H4F-4) were synthesized, by protonolysis of either the ate complex [Li3LnMe6(thf)n] (Ln = Sc, Y, Gd-Lu) or the tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = La-Nd, Sm, Dy, Gd) with ammonium borates [NR3H][BAr4] in thf. The number of coordinated thf ligands varied from n = 5 (Ln = Sc, Tm) to n = 6 (Ln = La, Y, Sm, Dy, Ho). The configuration of representative examples was determined by X-ray diffraction studies and confirmed by density-functional theory calculations. The highly polarized bonding between the methyl group and the rare-earth metal center results in the reactivity pattern dominated by the carbanionic character and the pronounced Lewis acidity: The dicationic methyl complex [YMe(thf)6](2+) inserted benzophenone as an electrophile to give the alkoxy complex [Y(OCMePh2)(thf)5](2+). Nucleophilic addition of

  17. New electrolyte systems for capillary zone electrophoresis of metal cations and non-ionic organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Y.

    1995-06-19

    Excellent separations of metal ions can be obtained very quickly by capillary electrophoresis provided a weak complexing reagent is incorporated into the electrolyte to alter the effective mobilities of the sample ions. Indirect photometric detection is possible by also adding a UV-sensitive ion to the electrolyte. Separations are described using phthalate, tartrate, lactate or hydroxyisobutyrate as the complexing reagent. A separation of twenty-seven metal ions was achieved in only 6 min using a lactate system. A mechanism for the separation of lanthanides is proposed for the hydroxyisobutyrate system.

  18. Conjugation of fatty acids with different lengths modulates the antibacterial and antifungal activity of a cationic biologically inactive peptide.

    Science.gov (United States)

    Malina, Amir; Shai, Yechiel

    2005-09-15

    Many studies have shown that an amphipathic structure and a threshold of hydrophobicity of the peptidic chain are crucial for the biological function of AMPs (antimicrobial peptides). However, the factors that dictate their cell selectivity are not yet clear. In the present study, we show that the attachment of aliphatic acids with different lengths (10, 12, 14 or 16 carbon atoms) to the N-terminus of a biologically inactive cationic peptide is sufficient to endow the resulting lipopeptides with lytic activity against different cells. Mode-of-action studies were performed with model phospholipid membranes mimicking those of bacterial, mammalian and fungal cells. These include determination of the structure in solution and membranes by using CD and ATR-FTIR (attenuated total reflectance Fourier-transform infrared) spectroscopy, membrane leakage experiments and by visualizing bacterial and fungal damage via transmission electron microscopy. The results obtained reveal that: (i) the short lipopeptides (10 and 12 carbons atoms) are non-haemolytic, active towards both bacteria and fungi and monomeric in solution. (ii) The long lipopeptides (14 and 16 carbons atoms) are highly antifungal, haemolytic only at concentrations above their MIC (minimal inhibitory concentration) values and aggregate in solution. (iii) All the lipopeptides adopt a partial alpha-helical structure in 1% lysophosphatidylcholine and bacterial and mammalian model membranes. However, the two short lipopeptides contain a significant fraction of random coil in fungal membranes, in agreement with their reduced antifungal activity. (iv) All the lipopeptides have a membranolytic effect on all types of cells assayed. Overall, the results reveal that the length of the aliphatic chain is sufficient to control the pathogen specificity of the lipopeptides, most probably by controlling both the overall hydrophobicity and the oligomeric state of the lipopeptides in solution. Besides providing us with basic

  19. A combined experimental and quantum mechanical investigation on some selected metal complexes of L-serine with first row transition metal cations

    Science.gov (United States)

    Mandal, Shilpi; Das, Gunajyoti; Askari, Hassan

    2015-02-01

    In the current study a joint solvent-free synthetic and computational approach has been adopted to explore the coordination properties of L-serine with the doubly charged cations of nickel, copper and zinc. The reaction products were characterized by elemental analyses, molar conductance, EDAX-SEM, TEM, TG/DTA, infrared, electronic absorption and fluorescence spectroscopy. Quantum chemical calculations, carried out in gas and aqueous phase using the BHandHLYP and MP2 methods in conjunction with 6-311++G(d,p) basis set, provide valuable insights concerning the interaction enthalpies and free energies; vibrational and absorption spectra along with various other molecular and electronic properties of the metal complexes. This study reveals that L-serine binds to the metal ions in a bi-dentate manner through its amino and carboxylate groups exhibiting highest binding affinity towards Cu(II) among the three metal ions considered here. As compared to the MP2 method, the spin-delocalized situations of the open-shell Cu(II) complex of L-serine have been better described at the BHandHLYP level. The physical origin of the molecular interactions of L-serine with the metal ions has also been examined by performing energy decomposition analysis (EDA). Effects of the aqueous environment are evident on the structure and stability of the metal complexes. The vibrational spectroscopic data furnished at MP2/6-311++G(d,p) level, which provide a good account of the structural changes inflicted in the molecular geometry of L-serine as a result of metal coordination, are in better agreement with our experimental observations as compared to those produced at the BHandHLYP/6-311++G(d,p) level.

  20. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

    2013-01-01

    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  1. Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant-metal(II) complexes.

    Science.gov (United States)

    Tawfik, Salah M; Hefni, Hassan H

    2016-01-01

    New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant.

  2. Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant-metal(II) complexes.

    Science.gov (United States)

    Tawfik, Salah M; Hefni, Hassan H

    2016-01-01

    New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant. PMID:26478092

  3. Vibrational study of isolated 18-crown-6 ether complexes with alkaline-earth metal cations

    NARCIS (Netherlands)

    Gamez, F.; Hurtado, P.; Martinez-Haya, B.; G. Berden,; Oomens, J.

    2011-01-01

    Laser infrared multiple photon dissociation (IRMPD) spectroscopy has been employed to probe the C-O and C-C stretching vibrational modes of 18-crown-6 ether (18c6) complexes with alkaline-earth metals (Mg(2+), Ca(2+). Sr(2+) and Ba(2+)) stored in the cell of a Fourier Transform Ion Cyclotron Resonan

  4. Vibrational study of isolated 18-crown-6 ether complexes with alkaline-earth metal cations

    NARCIS (Netherlands)

    F. Gámez; P. Hurtado; B. Martínez-Haya; G. Berden; J. Oomens

    2011-01-01

    Laser infrared multiple photon dissociation (IRMPD) spectroscopy has been employed to probe the C-O and C-C stretching vibrational modes of 18-crown-6 ether (18c6) complexes with alkaline-earth metals (Mg2+, Ca2+, Sr2+ and Ba2+) stored in the cell of a Fourier Transform Ion Cyclotron Resonance mass

  5. TOLERANCE OF AGAVE TEQUILANA TO HIGH LEVELS OF DIVALENT METAL CATIONS

    Directory of Open Access Journals (Sweden)

    Elmi Roseida Cen-Cen

    2015-11-01

    Full Text Available Los agaves son plantas que pertenecen a un género constituido por numerosas especies, adaptadas para crecer en muy diversos hábitats, algunos con condiciones ambientales extremas. Distintas especies de agave crecen sobre distintos tipos de suelos, algunas en suelos con muy bajo contenido de nutrientes minerales y otras en suelos salinos o en suelos contaminados con iones metálicos. La relación planta-suelo ha sido escasamente estudiada en este género por lo que se desconoce, entre otras cuestiones, cuál es la capacidad de los agaves para absorber, transportar y almacenar nutrientes minerales, cuáles son los mecanismos celulares y bioquímicos que utilizan, o si poseen especial sensibilidad o tolerancia a los iones metálicos. Este estudio reporta el efecto de diversas concentraciones de sulfato de cadmio, cobalto, cobre, zinc o de manganeso sobre plántulas deAgave tequilana, bajo condiciones controladas de laboratorio; la concentración mínima de esos iones metálicos requerida para inducir un efecto tóxico visualmente detectable en tiempos cortos (ocho días; describimos los efectos tóxicos que estos metales generan sobre las plántulas de agave; y reportamos la cantidad de Cu2+, Cd2+ y Co2+ que se acumula en las hojas de plántulas de agave tratadas con altas concentraciones (milimolares de esos metales. Nuestros resultados muestran que, en experimentos de toxicidad aguda y bajo las condiciones aquí establecidas, elA. tequilanaposee una notable tolerancia a altas concentraciones de los distintos metales iónicos probados, incluyendo tanto micronutrientes como metales tóxicos, así como la capacidad de transportar en altas cantidades estos metales a tejido aéreo.

  6. Fluorescence properties of riboflavin-functionalized mesoporous silica SBA-15 and riboflavin solutions in presence of different metal and organic cations

    Science.gov (United States)

    Lewandowski, Dawid; Schroeder, Grzegorz; Sawczak, Mirosław; Ossowski, Tadeusz

    2015-10-01

    Riboflavin was covalently linked to mesoporous SBA-15 silica surface via grafting technique. Then fluorescence properties of the system obtained were analyzed in the presence of several metal and organic cations. Both quenching and strengthening of fluorescence as well as significant changes in the maximum fluorescence wavelength were observed. The results were compared with absorption and fluorescence data obtained for riboflavin water solutions.

  7. Ceruloplasmin revisited: structural and functional roles of various metal cation-binding sites

    International Nuclear Information System (INIS)

    The three-dimensional molecular structure of human serum ceruloplasmin has been reinvestigated using X-ray synchrotron data collected at 100 K from a crystal frozen to liquid-nitrogen temperature. The three-dimensional molecular structure of human serum ceruloplasmin has been reinvestigated using X-ray synchrotron data collected at 100 K from a crystal frozen to liquid-nitrogen temperature. The resulting model, with an increase in resolution from 3.1 to 2.8 Å, gives an overall improvement of the molecular structure, in particular the side chains. In addition, it enables the clear definition of previously unidentified Ca2+-binding and Na+-binding sites. The Ca2+ cation is located in domain 1 in a configuration very similar to that found in the activated bovine factor Va. The Na+ sites appear to play a structural role in providing rigidity to the three protuberances on the top surface of the molecule. These features probably help to steer substrates towards the mononuclear copper sites prior to their oxidation and to restrict the size of the approaching substrate. The trinuclear copper centre appears to differ from the room-temperature structure in that a dioxygen moiety is bound in a similar way to that found in the endospore coat protein CotA from Bacillus subtilis

  8. Coordination Chemistry of Alkali and Alkaline-Earth Cations with Macrocyclic Ligands.

    Science.gov (United States)

    Dietrich, Bernard

    1985-01-01

    Discusses: (l) alkali and alkaline-earth cations in biology (considering naturally occurring lonophores, their X-ray structures, and physiochemical studies); (2) synthetic complexing agents for groups IA and IIA; and (3) ion transport across membranes (examining neutral macrobicyclic ligands as metal cation carriers, transport by anionic carriers,…

  9. The development of a biological interface for transition metal implants

    Science.gov (United States)

    Melton, Kim R.

    The specific goal of this research was to develop an in vitro model for a root-form endosseous dental implant that contains a periodontal ligament and that is biologically integratable into alveolar bone. This objective was based on the following two hypotheses. (1) The chemical attachment of extracellular matrix proteins to the surface of transition metals increases the number of fibroblast cells attached to the surface of the metal. (2) The chemical attachment of extracellular matrix proteins to the surface of transition metals increases the strength of the fibroblast cell attachment to the surface of the metal. The model needed to have a well-controlled surface that was reproducible. Thus, a layer of Au was deposited over a Ti base, and dithiobis(succinimidylpropionate) (DSP) a chemical containing disulfide groups was adsorbed to the Au. Next, extracellular matrix proteins which are periodontal ligament components were attached to the free end group of the chemical that was adsorbed to the Au. This surface served as an attachment substrate on which additional periodontal ligament components such as fibroblast cells could grow. From this model a new implant interface may be developed. This model was tested using the following polypeptides; collagen type I, collagen type IV, fibronectin, and poly-D-lysine. L929 cells were grown on Ti, Ti + Au, Ti + Au + polypeptide, and Ti + Au + DSP + polypeptide. After 72 hours, the live cells were stained with neutral red. The substrates were then subjected to increasing centrifugal forces. The viable stained cells were fixed onto the substrates and cells were counted. The hypotheses were proven for three polypeptides: fibronectin, collagen type I, and poly-D-lysine. The strongest attachment was found with collagen type I. Collagen type IV did not provide any advantage for attachment over uncoated transition metals.

  10. Macroscopic and bulk-controlled elastic modes in an interaction of interstitial alcali metal cations within a face-centered cubic crystalline fullerine

    International Nuclear Information System (INIS)

    The calculations in a majority of previous works for the fulleride (AqC60) crystals were performed within the framework of the rigid-lattice model, neglecting the distortion relaxation of the host fullerene (C60) crystal caused by the interstitial alkali-metal (A) cations. However, an each cation is a source of a static distoration field, and the resulting field is a superposition of such fields generated by all cations. This is a reason why the host-crystal distortions depend on the A-cations configurations, i.e. on a type of a spatial bulk distribution of interstitial cations. This paper seeks to find a functional relation between the amplitudes of the doping-induced structure-distortion waves and of statistic concentration ones. A semiphenomenological model is constructed here within the scope of statistical-thermodynamic treatment and using the lattice-statistics simulation method. In this model the effects due to the presence of q solute A cations over available interstices (per unit cell) on the statistic inherent reorientation and/or displacements of the solvent molecules from the average-lattice sites as well as on the lattice parameter a of the elastically-anysotropic cubic C60 crystal are taken into account

  11. Macroscopic and bulk-controlled elastic modes in an interaction of interstitial alcali metal cations within a face-centered cubic crystalline fullerine

    Energy Technology Data Exchange (ETDEWEB)

    Tatarenko, V.A.; Tsysman, C.L.; Oltarzhevskaya, Y.T.

    1995-04-01

    The calculations in a majority of previous works for the fulleride (AqC-60) crystals were performed within the framework of the rigid-lattice model, neglecting the distortion relaxation of the host fullerene (C-60) crystal caused by the interstitial alkali-metal (A) cations. However, an each cation is a source of a static distortion field, and the resulting field is a superposition of such fields generated by all cations. This is a reason why the host-crystal distortions depend on the A-cations configurations, i.e. on a type of a spatial bulk distribution of interstitial cations. The given paper seeks to find a functional relation between the amplitudes of the doping-induced structure-distortion waves and of static concentration ones. A semiphenomenological model is constructed here within the scope of statistical-thermodynamic treatment and using the lattice-statistics simulation method. In this model the effects due to the presence of q solute A cations over available interstices (per unit cell) on the static inherent reorientation and/or displacements of the solvent molecules from the `average-lattice` sites` as well as on the lattice parameter a of an elastically-anysotropic `cubic` C-60 crystal are taken into account.

  12. Macroscopic and bulk-controlled elastic modes in an interaction of interstitial alcali metal cations within a face-centered cubic crystalline fullerine

    Science.gov (United States)

    Tatarenko, Valentine A.; Tsysman, Constantin L.; Oltarzhevskaya, Yelena T.

    1995-01-01

    The calculations in a majority of previous works for the fulleride (AqC-60) crystals were performed within the framework of the rigid-lattice model, neglecting the distortion relaxation of the host fullerene (C-60) crystal caused by the interstitial alkali-metal (A) cations. However, an each cation is a source of a static distortion field, and the resulting field is a superposition of such fields generated by all cations. This is a reason why the host-crystal distortions depend on the A-cations configurations, i.e. on a type of a spatial bulk distribution of interstitial cations. The given paper seeks to find a functional relation between the amplitudes of the doping-induced structure-distortion waves and of static concentration ones. A semiphenomenological model is constructed here within the scope of statistical-thermodynamic treatment and using the lattice-statistics simulation method(*). In this model the effects due to the presence of q solute A cations over available interstices (per unit cell) on the static inherent reorientation and/or displacements of the solvent molecules from the 'average-lattice' sites' as well as on the lattice parameter a of a elastically-anysotropic 'cubic' C-60 crystal are taken into account.

  13. Macroscopic and bulk-controlled elastic modes in an interaction of interstitial alcali metal cations within a face-centered cubic crystalline fullerine

    Energy Technology Data Exchange (ETDEWEB)

    Tatarenko, V.A.; Tsysman, C.L.; Oltarzhevskaya, Y.T. [Institute for Metal Physics, Kiev (Ukraine)

    1994-12-31

    The calculations in a majority of previous works for the fulleride (AqC{sub 60}) crystals were performed within the framework of the rigid-lattice model, neglecting the distoration relaxation of the host fullerene (C{sub 60}) crystal caused by the interstitial alkali-metal (A) cations. However, an each cation is a source of a static distoration field, and the resulting field is a superposition of such fields generated by all cations. This is a reason why the host-crystal distortions depend on the A-cations configurations, i.e. on a type of a spatial bulk distribution of interstitial cations. This paper seeks to find a functional relation between the amplitudes of the doping-induced structure-distortion waves and of statistic concentration ones. A semiphenomenological model is constructed here within the scope of statistical-thermodynamic treatment and using the lattice-statistics simulation method. In this model the effects due to the presence of q solute A cations over available interstices (per unit cell) on the statistic inherent reorientation and/or displacements of the solvent molecules from the average-lattice sites as well as on the lattice parameter a of the elastically-anysotropic cubic C{sub 60} crystal are taken into account.

  14. Reversible CO binding enables tunable CO/H₂ and CO/N₂ separations in metal-organic frameworks with exposed divalent metal cations.

    Science.gov (United States)

    Bloch, Eric D; Hudson, Matthew R; Mason, Jarad A; Chavan, Sachin; Crocellà, Valentina; Howe, Joshua D; Lee, Kyuho; Dzubak, Allison L; Queen, Wendy L; Zadrozny, Joseph M; Geier, Stephen J; Lin, Li-Chiang; Gagliardi, Laura; Smit, Berend; Neaton, Jeffrey B; Bordiga, Silvia; Brown, Craig M; Long, Jeffrey R

    2014-07-30

    Six metal-organic frameworks of the M2(dobdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) structure type are demonstrated to bind carbon monoxide reversibly and at high capacity. Infrared spectra indicate that, upon coordination of CO to the divalent metal cations lining the pores within these frameworks, the C-O stretching frequency is blue-shifted, consistent with nonclassical metal-CO interactions. Structure determinations reveal M-CO distances ranging from 2.09(2) Å for M = Ni to 2.49(1) Å for M = Zn and M-C-O angles ranging from 161.2(7)° for M = Mg to 176.9(6)° for M = Fe. Electronic structure calculations employing density functional theory (DFT) resulted in good agreement with the trends apparent in the infrared spectra and crystal structures. These results represent the first crystallographically characterized magnesium and zinc carbonyl compounds and the first high-spin manganese(II), iron(II), cobalt(II), and nickel(II) carbonyl species. Adsorption isotherms indicate reversible adsorption, with capacities for the Fe, Co, and Ni frameworks approaching one CO per metal cation site at 1 bar, corresponding to loadings as high as 6.0 mmol/g and 157 cm(3)/cm(3). The six frameworks display (negative) isosteric heats of CO adsorption ranging from 52.7 to 27.2 kJ/mol along the series Ni > Co > Fe > Mg > Mn > Zn, following the Irving-Williams stability order. The reversible CO binding suggests that these frameworks may be of utility for the separation of CO from various industrial gas mixtures, including CO/H2 and CO/N2. Selectivities determined from gas adsorption isotherm data using ideal adsorbed solution theory (IAST) over a range of gas compositions at 1 bar and 298 K indicate that all six M2(dobdc) frameworks could potentially be used as solid adsorbents to replace current cryogenic distillation technologies, with the choice of M dictating adsorbent regeneration energy and the level of purity of the resulting gases.

  15. 2013 METALS IN BIOLOGY GORDON RESEARCH CONFERENCE, JANUARY 20-25, 2013

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, Amy

    2013-01-25

    Typical topics for lectures and posters include: biochemical and biophysical characterization of new metal containing proteins, enzymes, nucleic acids, factors, and chelators from all forms of life; synthesis, detailed characterization, and reaction chemistry of biomimetic compounds; novel crystal and solution structures of biological molecules and synthetic metal-chelates; discussions of the roles that metals play in medicine, maintenance of the environment, and biogeochemical processes; metal homeostasis; application of theory and computations to the structure and mechanism of metal-containing biological systems; and novel applications of spectroscopy to metals in biological systems.

  16. Synthesis and spectral characterization of a new blue fluorescent tripod for detecting metal cations and protons

    Energy Technology Data Exchange (ETDEWEB)

    Staneva, Desislava [University of Chemical Technology and Metallurgy, 1756 Sofia (Bulgaria); Makki, Mohammad S.I.; Sobahi, Tariq R. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Bosch, Paula [Institute of Science and Technology of Polymers, CSIC, Juan de la Cierva 3, 28006, Madrid (Spain); Abdel-Rahman, Reda M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Asiri, Abdullah [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Grabchev, Ivo, E-mail: i.grabchev@chem.uni-sofia.bg [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Sofia University “St. Kliment Ohridski”, Faculty of Medicine, 1407 Sofia (Bulgaria)

    2015-06-15

    A new symmetrical blue fluorescent tripod containing three 1,8-naphtalimide fragments has been synthesized. Its spectral properties have been investigated in organic solvents of different polarity. Its basic photophysical characteristics depend strongly on the polarity of the organic solvents. In nonpolar solvents (diethyl ether, chloroform and toluene) the new tripod emits eximer fluorescence. The new tripod has been investigated as a ligand for detection of metal ions (Ag{sup +}, Co{sup 2+}, Pb{sup 2+}, Zn{sup 2+}, Ni{sup 2+}, and Cu{sup 2+}) in acetonitrile and acetonitrile/H{sub 2}O (1:4, v/v). The influence of protons in an ethanol–water (1:4, v/v) solution and in toluene and diethyl ether solvents on the tripod fluorescence intensity has been investigated and it has been shown that the protons destroy the excimer formations recovering the monomer fluorescence. - Highlights: • New blue fluorescent tripod containing three 1,8-naphtalimide fragments was described. • In nonpolar solvents the new tripod emits eximer fluorescence. • The new tripod has been investigated as a ligand for metal ions and protons.

  17. Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

    Science.gov (United States)

    Ajisaka, Katsumi; Oyanagi, Yutaka; Miyazaki, Tatsuo; Suzuki, Yasuhiro

    2016-06-01

    The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions. PMID:26856546

  18. Biological metals and metal-targeting compounds in major neurodegenerative diseases.

    Science.gov (United States)

    Barnham, Kevin J; Bush, Ashley I

    2014-10-01

    Multiple abnormalities occur in the homeostasis of essential endogenous brain biometals in age-related neurodegenerative disorders, Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. As a result, metals both accumulate in microscopic proteinopathies, and can be deficient in cells or cellular compartments. Therefore, bulk measurement of metal content in brain tissue samples reveal only the "tip of the iceberg", with most of the important changes occurring on a microscopic and biochemical level. Each of the major proteins implicated in these disorders interacts with biological transition metals. Tau and the amyloid protein precursor have important roles in normal neuronal iron homeostasis. Changes in metal distribution, cellular deficiencies, or sequestration in proteinopathies all present abnormalities that can be corrected in animal models by small molecules. These biochemical targets are more complex than the simple excess of metals that are targeted by chelators. In this review we illustrate some of the richness in the science that has developed in the study of metals in neurodegeneration, and explore its novel pharmacology.

  19. Hetero-metal cation control of CuO nanostructures and their high catalytic performance for CO oxidation

    Science.gov (United States)

    Huang, Hongwen; Zhang, Liqiang; Wu, Kewei; Yu, Qing; Chen, Ru; Yang, Hangsheng; Peng, Xinsheng; Ye, Zhizhen

    2012-11-01

    A controllable synthesis of various morphologies of CuO nanostructures with tuning by hetero-metal cations has been developed in aqueous solution at room temperature. The morphologies of CuO can be engineered from nanosheets to nanoparticles with different length ratios of the long axis to the short axis. The formation of many metal-ion complexes plays an important role in slowing the release rate of OH- and affects the reaction kinetics further. We found that the effect of hetero-metal cations on the final morphology of the CuO nanostructures was the same as that of the cooling temperature. A series of temperature-controlled experiments demonstrated this. Furthermore, among all the synthesized CuO nanostructures, the fascinating colloidal mesoporous CuO quasi-monocrystalline nanosheets prepared at 25 °C with a thickness of ca. 10 nm and large specific surface area of 80.32 m2 g-1 is investigated intensively. These CuO nanosheets demonstrate a superior catalytic activity for CO oxidation, with features of high CO conversion efficiency (47.77 mmolCO g-1CuO h-1 at 200 °C), which is close to that reported for previously investigated supported-CuO catalysts, and a low apparent activation energy Ea (53.3 kJ mol-1).A controllable synthesis of various morphologies of CuO nanostructures with tuning by hetero-metal cations has been developed in aqueous solution at room temperature. The morphologies of CuO can be engineered from nanosheets to nanoparticles with different length ratios of the long axis to the short axis. The formation of many metal-ion complexes plays an important role in slowing the release rate of OH- and affects the reaction kinetics further. We found that the effect of hetero-metal cations on the final morphology of the CuO nanostructures was the same as that of the cooling temperature. A series of temperature-controlled experiments demonstrated this. Furthermore, among all the synthesized CuO nanostructures, the fascinating colloidal mesoporous Cu

  20. Energy decomposition analysis of cation-π, metal ion-lone pair, hydrogen bonded, charge-assisted hydrogen bonded, and π-π interactions.

    Science.gov (United States)

    Sharma, Bhaskar; Srivastava, Hemant Kumar; Gayatri, Gaddamanugu; Sastry, Garikapati Narahari

    2015-03-30

    This study probes the nature of noncovalent interactions, such as cation-π, metal ion-lone pair (M-LP), hydrogen bonding (HB), charge-assisted hydrogen bonding (CAHB), and π-π interactions, using energy decomposition schemes-density functional theory (DFT)-symmetry-adapted perturbation theory and reduced variational space. Among cation-π complexes, the polarization and electrostatic components are the major contributors to the interaction energy (IE) for metal ion-π complexes, while for onium ion-π complexes (NH4+, PH4+, OH3+, and SH3+) the dispersion component is prominent. For M-LP complexes, the electrostatic component contributes more to the IE except the dicationic metal ion complexes with H2 S and PH3 where the polarization component dominates. Although electrostatic component dominates for the HB and CAHB complexes, dispersion is predominant in π-π complexes.

  1. Effect of Siloxane Ring Strain and Cation Charge Density on the Formation of Coordinately Unsaturated Metal Sites on Silica: Insights from DFT Studies

    Energy Technology Data Exchange (ETDEWEB)

    Das, Ujjal; Zhang, Guanghui; Hu, Bo; Hock, Adam S.; Redfern, Paul C.; Miller, Jeffrey T.; Curtiss, Larry A.

    2015-12-01

    Amorphous silica (SiO2) is commonly used as a support in heterogeneous catalysis. However, due to the structural disorder and temperature induced change of surface morphology, the structures of silica supported metal catalysts are difficult to determine. Most studies are primarily focused on understanding the interactions of different types of surface hydroxyl groups with metal ions. In comparison, the effect of siloxane ring size on the structure of silica supported metal catalysts and how it affects catalytic activity is poorly understood. Here, we have used density functional theory calculations to understand the effect of siloxane ring strain on structure and activity of different monomeric Lewis acid metal sites on silica. In particular, we have found that large siloxane rings favor strong dative bonding interaction between metal ion and surface hydroxyls, leading to the formation of high-coordinate metal sites. In comparison, metal-silanol interaction is weak in small siloxane rings, resulting in low-coordinate metal sites. The physical origin of this size dependence is associated with siloxane ring strain, and, a correlation between metal-silanol interaction energy and ring strain energy has been observed. In addition to ring strain, the strength of the metal-silanol interaction also depends on the positive charge density of the cations. In fact, a correlation also exists between metal-silanol interaction energy and charge density of several first-row transition and post-transition metals. The theoretical results are compared with the EXAFS data of monomeric Zn(II) and Ga(III) ions grafted on silica. The molecular level insights of how metal ion coordination on silica depends on siloxane ring strain and cation charge density will be useful in the synthesis of new catalysts.

  2. Optical Properties and Biological Applications of Electromagnetically Coupled Metal Nanoparticles

    Science.gov (United States)

    Sheikholeslami, Sassan Nathan

    The optical properties of metallic particles change dramatically as the size shrinks to the nanoscale. The familiar mirror-like sheen of bulk metals is replaced by the bright, sharp, colorful plasmonic resonances of nanoparticles. The resonances of plasmonic metal nanoparticles are highly tunable throughout the visible spectrum, depending on the size, shape, local dielectric environment, and proximity to other optical resonances. Fundamental and applied research in the nanoscience community in the past few decades has sought to understand and exploit these phenomena for biological applications. In this work, discrete nanoparticle assemblies were produced through biomolecular interactions and studied at the single particle level with darkfield spectroscopy. Pairs of gold nanoparticles tethered by DNA were utilized as molecular rulers to study the dynamics of DNA bending by the restriction enzyme EcoRV. These results substantiated that nanoparticle rulers, deemed "plasmon rulers", could measure the dynamics of single biomolecules with high throughput, long lifetime, and high temporal resolution. To extend these concepts for live cell studies, a plasmon ruler comprised of peptide-linked gold nanoparticle satellites around a core particle was synthesized and utilized to optically follow cell signaling pathways in vivo at the single molecule level. The signal provided by these plasmon rulers allowed continuous observation of caspase-3 activation at the single molecule level in living cells for over 2 hours, unambiguously identifying early stage activation of caspase-3 in apoptotic cells. In the last section of this dissertation, an experimental and theoretical study of electomagnetic coupling in asymmetric metal nanoparticle dimers is presented. A "heterodimer" composed of a silver particle and a gold particle is observed to have a novel coupling between a plasmon mode (free electron oscillations) and an inter-band absorption process (bound electron transitions). The

  3. Metal cation cross-linked nanocellulose hydrogels as tissue engineering substrates.

    Science.gov (United States)

    Zander, Nicole E; Dong, Hong; Steele, Joshua; Grant, John T

    2014-01-01

    The use of cellulose materials for biomedical applications is attractive due to their low cost, biocompatibility, and biodegradability. Specific processing of cellulose to yield nanofibrils further improves mechanical properties and suitability as a tissue engineering substrate due to the similarity to the fibrous structure, porosity, and size-scale of the native extracellular matrix. In order to generate the substrate, nanocellulose hydrogels were fabricated from carboxylated cellulose nanofibrils via hydrogelation using metal salts. Hydrogels cross-linked with Ca(2+) and Fe(3+) were investigated as tissue culture substrates for C3H10T1/2 fibroblast cells. Control substrates as well as those with physically adsorbed and covalently attached fibronectin protein were evaluated with X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and enzyme linked immunosorbent assay (ELISA). Significantly more cells were attached to surfaces modified with protein, with the highest number of cells adhered to the calcium cross-linked hydrogels with covalently attached protein.

  4. The biological chemistry of the transition metal "transportome" of Cupriavidus metallidurans.

    Science.gov (United States)

    Nies, Dietrich H

    2016-05-01

    This review tries to illuminate how the bacterium Cupriavidus metallidurans CH34 is able to allocate essential transition metal cations to their target proteins although these metals have similar charge-to-surface ratios and chemical features, exert toxic effects, compete with each other, and occur in the bacterial environment over a huge range of concentrations and speciations. Central to this ability is the "transportome", the totality of all interacting metal import and export systems, which, as an emergent feature, transforms the environmental metal content and speciation into the cellular metal mélange. In a kinetic flow equilibrium resulting from controlled uptake and efflux reactions, the periplasmic and cytoplasmic metal content is adjusted in a way that minimizes toxic effects. A central core function of the transportome is to shape the metal ion composition using high-rate and low-specificity reactions to avoid time and/or energy-requiring metal discrimination reactions. This core is augmented by metal-specific channels that may even deliver metals all the way from outside of the cell to the cytoplasm. This review begins with a description of the basic chemical features of transition metal cations and the biochemical consequences of these attributes, and which transition metals are available to C. metallidurans. It then illustrates how the environment influences the metal content and speciation, and how the transportome adjusts this metal content. It concludes with an outlook on the fate of metals in the cytoplasm. By generalization, insights coming from C. metallidurans shed light on multiple transition metal homoeostatic mechanisms in all kinds of bacteria including pathogenic species, where the "battle" for metals is an important part of the host-pathogen interaction. PMID:27065183

  5. Liquid Exfoliation of Layered Transition Metal Dichalcogenides for Biological Applications.

    Science.gov (United States)

    Nguyen, Emily P; Daeneke, Torben; Zhuiykov, Serge; Kalantar-Zadeh, Kourosh

    2016-06-02

    Known to possess distinctive properties that differ greatly from their bulk form, layered two-dimensional materials have been extensively studied and incorporated into many versatile applications ranging from optoelectronics to sensors. For biomedical research, two-dimensional transition metal dichalcogenides (2D TMDs) have garnered much interest as they have been shown to exhibit relatively low toxicity, high stability in aqueous environments, and the ability to adhere to biological materials such as proteins. These materials are promising candidates, demonstrating potential applications in biosensing, cell imaging, diagnostics, and therapeutics. Preparation and exfoliation of 2D TMDs play an important part in these various applications as their properties are heavily dependent on the number of layers and lateral size. Described in this article are protocols for the liquid exfoliation of 2D TMDs from their bulk materials. Additional protocols are also provided for functionalizing or modifying the surface of the exfoliated 2D TMDs. © 2016 by John Wiley & Sons, Inc.

  6. Sorption of metal cations on suspended bentonite. Effects of pH, ionic strength and complexing anions

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Parveen Kumar; Pathak, Priyanath; Mohapatra, Prasanta Kumar [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.

    2014-07-01

    Batch sorption experiments have been carried out to understand the interaction of different metal cations such as Am(III), Eu(III), Sr(II), and Cs(I) with bentonite clay at varying pH (1-9). The effects of other experimental parameters such as ionic strength (0.01-1 M (NaClO{sub 4})), clay to metal ion concentration ratio, and the presence of complexing anions such as oxalic acid (ox), carbonate (CO{sub 3}{sup 2-}), ethylenediaminetetraacetic acid (EDTA), and humic acid (HA) on Eu(III) sorption have also been investigated. The sorption of Eu(III) has been found to be invariant with the change in ionic strength suggesting inner-sphere complexation on the bentonite surface. Near quantitative sorption of Eu(III) and Am(III) has been observed in the entire pH range and there is marginal influence of the presence of 1 x 10{sup -4} M of ox and CO{sub 3}{sup 2-} on the sorption profile. However, the presence of 1 x 10{sup -4} M EDTA suppresses the sorption of Eu(III) ion onto bentonite. Desorption studies of Eu(III) loaded onto bentonite using varying concentrations of HClO{sub 4} (0.01-1.0 M) solutions reveal that higher acidity favors the process. The sorption of Eu(III) on bentonite followed the Langmuir isotherm suggesting monolayer sorption process. The data fitting to D-R isotherm suggested that the Eu(III) sorption on bentonite follows ion exchange mechanism. The sorption capacity of bentonite clay was determined to be 3.8(±0.1) x 10{sup -4} moles/g using Langmuir and D-R isotherms. (orig.)

  7. Effect of transition metal cations on commensurate freezing of n-hexane confined in micropores of ZSM-5

    Directory of Open Access Journals (Sweden)

    Hercigonja Radmila

    2015-01-01

    Full Text Available Besides its importance concerning fundamental studies on gas adsorption in narrow pores, investigation of commensurate freezing of fluid within the zeolite is of practical importance in application of zeolite in the process of adsorption, separation and catalysis. In this work the adsorption of n-hexane on HZSM-5 and its transition metal ion-exchanged modified forms was studied at 303 K by means of microcalorimetry. The thermal molar entropies of adsorption were calculated and thus, the freezing like behaviour of n-hexane inside the structure of zeolite as a confinement media was noticed. This effect is governed by the attractive interactions between n-hexane molecules and the pore walls, and is also influenced by the length of the pores and the nature of charge-balancing cations. Among the investigated zeolites, solid like phase of n-hexane in the pores of zeolites with Fe2+ ions is the most like a solid n-hexane bulk, while the presence of Cu2+ ions contribute to the lowest ordering obtained solid like phase of n-hexane. [Projekat Ministarstva nauke Republike Srbije, br. 172018

  8. Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation

    Institute of Scientific and Technical Information of China (English)

    Milad Rasouli; Nakisa Yaghobi; Hossein Atashi; Majid Rasouli

    2015-01-01

    The adsorption process was studied for separating para-xylene from xylene mixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO2/Al2O3 was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C8 aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C8 aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylben-zene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

  9. Alginate and Algal-Based Beads for the Sorption of Metal Cations: Cu(II) and Pb(II).

    Science.gov (United States)

    Wang, Shengye; Vincent, Thierry; Faur, Catherine; Guibal, Eric

    2016-01-01

    Alginate and algal-biomass (Laminaria digitata) beads were prepared by homogeneous Ca ionotropic gelation. In addition, glutaraldehyde-crosslinked poly (ethyleneimine) (PEI) was incorporated into algal beads. The three sorbents were characterized by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX): the sorption occurs in the whole mass of the sorbents. Sorption experiments were conducted to evaluate the impact of pH, sorption isotherms, and uptake kinetics. A special attention was paid to the effect of drying (air-drying vs. freeze-drying) on the mass transfer properties. For alginate, freeze drying is required for maintaining the porosity of the hydrogel, while for algal-based sorbents the swelling of the material minimizes the impact of the drying procedure. The maximum sorption capacities observed from experiments were 415, 296 and 218 mg Pb g(-1) and 112, 77 and 67 mg Cu g(-1) for alginate, algal and algal/PEI beads respectively. Though the sorption capacities of algal-beads decreased slightly (compared to alginate beads), the greener and cheaper one-pot synthesis of algal beads makes this sorbent more competitive for environmental applications. PEI in algal beads decreases the sorption properties in the case of the sorption of metal cations under selected experimental conditions. PMID:27598128

  10. Reversible, Selective Trapping of Perchlorate from Water in Record Capacity by a Cationic Metal-Organic Framework.

    Science.gov (United States)

    Colinas, Ian R; Silva, Rachel C; Oliver, Scott R J

    2016-02-16

    We report the capture of ppm-level aqueous perchlorate in record capacity and kinetics via the complete anion exchange of a cationic metal-organic framework. Ambient conditions were used for both the synthesis of silver 4,4'-bipyridine nitrate (SBN) and the exchange, forming silver 4,4'-bipyridine perchlorate (SBP). The exchange was complete within 90 min, and the capacity was 354 mg/g, representing 99% removal. These values are greater than current anion exchangers such as the resins Amberlite IRA-400 (249 mg/g), Purolite A530E (104 mg/g), and layered double hydroxides (28 mg/g). Moreover, unlike resins and layered double hydroxides, SBN is fully reusable and displays 96% regeneration to SBN in nitrate solution, with new crystal formation allowing the indefinite cycling for perchlorate. We show seven cycles as proof of concept. Perchlorate contamination of water represents a serious health threat because it is a thyroid endocrine disruptor. This noncomplexing anionic pollutant is significantly mobile and environmentally persistent. Removal of other anionic pollutants from water such as chromate, pertechnetate, or arsenate may be possible by this methodology. PMID:26765213

  11. Current Understanding of the Binding Sites, Capacity, Affinity, and Biological Significance of Metals in Melanin

    OpenAIRE

    Hong, Lian; Simon, John D.

    2007-01-01

    Metal chelation is often invoked as one of the main biological functions of melanin. In order to understand the interaction between metals and melanin, extensive studies have been carried out to determine the nature of the metal binding sites, binding capacity and affinity. These data are central to efforts aimed at elucidating the role metal binding plays in determining the physical, structural, biological, and photochemical properties of melanin. This article examines the current state of u...

  12. Synthesis of metal-metal oxide catalysts and electrocatalysts using a metal cation adsorption/reduction and adatom replacement by more noble ones

    Science.gov (United States)

    Adzic, Radoslav; Vukmirovic, Miomir; Sasaki, Kotaro

    2010-04-27

    The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen. The invention also relates to methods of making the metal-metal oxide composites.

  13. Dynamic chiral-at-metal stability of tetrakis(d/l-hfc)Ln(III) complexes capped with an alkali metal cation in solution.

    Science.gov (United States)

    Lin, Yiji; Zou, Fang; Wan, Shigang; Ouyang, Jie; Lin, Lirong; Zhang, Hui

    2012-06-14

    Chiral tetrakis(β-diketonate) Ln(III) complexes Δ-[NaLa(d-hfc)(4)(CH(3)CN)] (1) and Λ-[NaLa(l-hfc)(4) (CH(3)CN)] (2) (d/l-hfc(-) = 3-heptafluo-robutylryl-(+)/(-)-camphorate) are a pair of enantiomers and crystallize in the same Sohncke space group (P2(1)2(1)2(1)) with dodecahedral (DD) geometry. Typically positive and negative exciton splitting patterns around 320 nm were observed in the solid-state circular dichroism (CD) spectra of complexes 1 and 2, which indicate that their shell configurational chiralities are Δ and Λ, respectively. The apparent bisignate couplets in the solid-state CD spectra of [CsLn(d-hfc)(4)(H(2)O)] [Ln = La (3), Yb (5)] and [CsLn(l-hfc)(4)(H(2)O)] [Ln = La (4), Yb (6)] show that they are a pair of enantiomers and their absolute configurations are denoted Δ and Λ, respectively. The crystallographic data of 5 reveals that its coordination polyhedron is the square antiprism (SAP) geometry and it undergoes a phase transition from triclinic (α phase, P1) to monoclinic (β phase, C2) upon cooling. The difference between the two phases is brought about by the temperature dependent behaviour of the coordination water molecules, but this did not affect the configurational chirality of the Δ-SAP-[Yb(d-hfc)(4)](-) moiety. Furthermore, time-dependent CD, UV-vis and (19)F NMR were applied to study the solution behavior of these complexes. It was found that the chiral-at-metal stability of the three pairs of complexes is different and affected by both the Ln(3+) and M(+) ion size. The results show that the Cs(+) cation can retain the metal center chirality and stablize the structures of [Ln(d/l-hfc)(4)](-) or the dissociated tris(d/l-hfc)Ln(III) species in solution for a longer time than that of the Na(+) cation, and it is important that the Cs(+) ion successfully lock the configurational chirality around the Yb(3+) center of the complex species in solution. This is reasoned by the short Cs(+)···FC, Cs(+)···O-Yb and Cs(+)···Yb(3

  14. Drivers of Tree Species Effects on Phosphorus and Cation Cycling in Plantations at La Selva Biological Station, Costa Rica

    Science.gov (United States)

    Russell, A. E.

    2014-12-01

    Fast-growing trees in secondary forests and plantations in the humid tropics play an important role in the atmospheric CO2 balance owing to their high rates of carbon sequestration. Because plants require nutrients to sustain high CO2 uptake, differences among tree species in traits related to nutrient uptake, retention and recycling could influence ecosystem-scale carbon cycling. A better understanding of the relationships among plant traits, nutrient and carbon cycling will thus improve ecosystem- to global scale modeling of effects of vegetation change on carbon cycling. In an experimental setting in which state factors were similar among four species of tropical trees situated on an Oxisol in replicated, 25-yr-old, mono-dominant plantations, I evaluated various drivers of aboveground storage of phosphorus (P) and cations, measuring nutrient fluxes in litterfall and fine-root growth and storage in biomass and soil to 1-m depth. Because fine roots increase the capacity to scavenge nutrients already on exchange sites within the soil environment, I hypothesized that P and cation uptake would be correlated directly with fine-root growth. The four tree species in this experiment, Hieronyma alchorneoides, Pentaclethra macroloba, Virola koschnyi, and Vochysia guatemalensis differed significantly in net cation uptake over the first 25 years of growth (P = 0.013, Ca; P >0.0001, Mg, Mn, K, Al, Fe, and Sr). For all cations, aboveground tree biomass was highly correlated with fine-root ingrowth length, with P values >0.0001 for all cations except Ca (P = 0.013). In contrast for P, differences among species were only marginally significant (P = 0.062). Similarly, P in aboveground tree biomass was marginally correlated with fine-root ingrowth (P = 0.068). Neither cation nor P uptake was correlated with measures of available P and cations, organic or total P in surface soil. For P, the less significant correlation with fine-root growth suggests that some other mechanism, such

  15. The Stabilized Cation Pool Method: Metal- and Oxidant-Free Benzylic C-H/Aromatic C-H Cross-Coupling.

    Science.gov (United States)

    Hayashi, Ryutaro; Shimizu, Akihiro; Yoshida, Jun-Ichi

    2016-07-13

    Electrochemical oxidation of toluene derivatives in the presence of a sulfilimine gave benzylaminosulfonium ions as stabilized benzyl cation pools, which reacted with subsequently added aromatic nucleophiles to give the corresponding cross-coupling products. The transformation serves as a powerful metal- and chemical-oxidant-free method for benzylic C-H/aromatic C-H cross-coupling. The method has been successfully applied to synthesis of TP27, an inhibitor of PTPase. PMID:27341676

  16. Biological attributes of rehabilitated soils contaminated with heavy metals.

    Science.gov (United States)

    Valentim Dos Santos, Jessé; Varón-López, Maryeimy; Fonsêca Sousa Soares, Cláudio Roberto; Lopes Leal, Patrícia; Siqueira, José Oswaldo; de Souza Moreira, Fatima Maria

    2016-04-01

    This study aimed to evaluate the effects of two rehabilitation systems in sites contaminated by Zn, Cu, Pb, and Cd on biological soil attributes [microbial biomass carbon (Cmic), basal and induced respiration, enzymatic activities, microorganism plate count, and bacterial and fungal community diversity and structure by denaturing gradient gel electrophoresis (DGGE)]. These systems (S1 and S2) consisted of excavation (trenching) and replacement of contaminated soil by uncontaminated soil in rows with Eucalyptus camaldulensis planting (S1-R and S2-R), free of understory vegetation (S1-BR), or completely covered by Brachiaria decumbens (S2-BR) in between rows. A contaminated, non-rehabilitated (NR) site and two contamination-free sites [Cerrado (C) and pasture (P)] were used as controls. Cmic, densities of bacteria and actinobacteria, and enzymatic activities (β-glucosidase, acid phosphatase, and urease) were significantly higher in the rehabilitated sites of system 2 (S2-R and S2-BR). However, even under high heavy metal contents (S1-R), the rehabilitation with eucalyptus was also effective. DGGE analysis revealed similarity in the diversity and structure of bacteria and fungi communities between rehabilitated sites and C site (uncontaminated). Principal component analysis showed clustering of rehabilitated sites (S2-R and S2-BR) with contamination-free sites, and S1-R was intermediate between the most and least contaminated sites, demonstrating that the soil replacement and revegetation improved the biological condition of the soil. The attributes that most explained these clustering were bacterial density, acid phosphatase, β-glucosidase, fungal and actinobacterial densities, Cmic, and induced respiration. PMID:26662102

  17. Influence of amphotericin B on liquid crystal state of the Cholesterol/Dipalmitoylphosphatidylcholine monolayer in the presence of different metal cations

    Science.gov (United States)

    Wang, Juan; Shi, Rui-Xin; Sun, Run-Guang; Hao, Chang-Chun; Li, Jun-Hua; Lu, Xiao-Long

    2016-09-01

    Amphotericin B is a very effective antifungal drug, but it has an adverse reaction to the membrane of mammals’ cells. The interaction between AmB and cholesterol (Chol) causes the formation of pores on the membrane to destroy its integrity. In particular, AmB has a significant effect on the permeability of membrane for K+ ions. It has been reported that Na+ ions and Ca2+ ions may have some influence on the interaction between amphotericin B and lipid molecules. In this work, the effects of these metal cations on the physical state and intermolecular interaction of the Cholesterol/ Dipalmitoylphosphatidylcholine (Chol/DPPC) monolayer with and without AmB have been investigated. The addition of AmB induces the change of physical state of the lipid monolayer from liquid-gel phase to liquid phase. Different metal cations could influence the phase transition of the AmB-lipid monolayer. The K+ ions and Ca2+ ions make the obvious phase transition disappear. However, the presence of Na+ ions has little influence on the phase transition of the AmB-lipid monolayer. The addition of AmB and the presence of different metal cations weaken the attractive force on the monolayers. After addition of AmB, the force between the molecules is the strongest in the environment of K+ ions, thus is the weakest in the environment of Ca2+ ions, which may be due to the distribution of these metal cations inside and outside of cells. A large number of K+ ions distribute inside of the cells, thus most of Na+ and Ca2+ ions exist out of the cells. Hence, it may be possible that when AmB molecules are out of the cells, the reaction between the drug and lipid molecules is weaker than that inside the cells. These results may have a great reference value for further studying the toxicity mechanism of AmB and the influence of metal cations on the membrane. Project supported by the National Natural Science Foundation of China (Grant Nos. 21402114 and 11544009), the Natural Science Basic Research Plan

  18. Incorporation of transition metals into Mg-Al layered double hydroxides: Coprecipitation of cations vs. their pre-complexation with an anionic chelator

    International Nuclear Information System (INIS)

    A comparative study on two different methods for preparing Mg-Al layered double hydroxides (LDH) containing various divalent transition metals M (M=Co, Ni, Cu) has been carried out. The first (conventional) method involved coprecipitation of divalent metals M(II) with Mg(II) and Al(III) cations using carbonate under basic conditions. The second approach was based on the ability of transition metals to form stable anionic chelates with edta4- (edta4-=ethylenediaminetetraacetate) that were synthesized and further introduced into LDH by coprecipitation with Mg and Al. The synthesized LDHs were characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF) methods, thermogravimetry with mass-selective detection of decomposition products (TG-MSD), Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The results obtained were discussed in terms of efficiency of transition metal incorporation into the LDH structure, thermal stability of materials and the ability of metal chelates to intercalate the interlayer space of Mg-Al LDH. Vibrational spectroscopy studies confirmed that the integrity of the metal chelates was preserved upon incorporation into the LDH. - Graphical abstract: Two ways for introducing transition metals M(II) into Mg-Al layered double hydroxides (MY2- denotes the edta chelate of transition metal M(II))

  19. Facilitated alkali ion transfer at the water 1,2-dichloroethane interphase Ab-initio calculations concerning alkaline metal cation - 1,10-phenanthroline complexes

    CERN Document Server

    Sánchez, C; Baruzzi, A M; Leiva, E P M

    1997-01-01

    A series of calculations on the energetics of complexation of alkaline metals with 1,10-phenanthroline are presented. It is an experimental fact that the ordering of the free energy of transfer across the water - 1,2-dichloroethane interphase is governed by the charge / size ratio of the diferent cations; the larger cations showing the lower free energy of transfer. This ordering of the free energies of transfer is reverted in the presence of 1,10-phenanthroline in the organic phase. We have devised a thermodynamic cycle for the transfer process and by means of ab-initio calculations have drawn the conclusion that in the presence of phen the free energy of transfer is governed by the stability of the PHEN/M $^{+}$complex, which explains the observed tendency from a theoretical point of view.

  20. Effect of metal cation replacement on the electronic structure of metalorganic halide perovskites: Replacement of lead with alkaline-earth metals

    Science.gov (United States)

    Pazoki, Meysam; Jacobsson, T. Jesper; Hagfeldt, Anders; Boschloo, Gerrit; Edvinsson, Tomas

    2016-04-01

    Organic and inorganic lead halogen perovskites, and in particular, C H3N H3Pb I3 , have during the last years emerged as a class of highly efficient solar cell materials. Herein we introduce metalorganic halogen perovskite materials for energy-relevant applications based on alkaline-earth metals. Based on the classical notion of Goldschmidt's rules and quantum mechanical considerations, the three alkaline-earth metals, Ca, Sr, and Ba, are shown to be able to exchange lead in the perovskite structure. The three alkaline-earth perovskites, C H3N H3Ca I3,C H3N H3Sr I3 , and C H3N H3Ba I3 , as well as the reference compound, C H3N H3Pb I3 , are in this paper investigated with density functional theory (DFT) calculations, which predict these compounds to exist as stable perovskite materials, and their electronic properties are explored. A detailed analysis of the projected molecular orbital density of states and electronic band structure from DFT calculations were used for interpretation of the band-gap variations in these materials and for estimation of the effective masses of the electrons and holes. Neglecting spin-orbit effects, the band gap of MACa I3,MASr I3 , and MABa I3 were estimated to be 2.95, 3.6, and 3.3 eV, respectively, showing the relative change expected for metal cation exchange. The shifts in the conduction band (CB) edges for the alkaline-earth perovskites were quantified using scalar relativistic DFT calculations and tight-binding analysis, and were compared to the situation in the more extensively studied lead halide perovskite, C H3N H3Pb I3 , where the change in the work function of the metal is the single most important factor in tuning the CB edge and band gap. The results show that alkaline-earth-based organometallic perovskites will not work as an efficient light absorber in photovoltaic applications but instead could be applicable as charge-selective contact materials. The rather high CB edge and the wide band gap together with the large

  1. [Biological activity of selenorganic compounds at heavy metal salts intoxication].

    Science.gov (United States)

    Rusetskaya, N Y; Borodulin, V B

    2015-01-01

    Possible mechanisms of the antitoxic action of organoselenium compounds in heavy metal poisoning have been considered. Heavy metal toxicity associated with intensification of free radical oxidation, suppression of the antioxidant system, damage to macromolecules, mitochondria and the genetic material can cause apoptotic cell death or the development of carcinogenesis. Organic selenium compounds are effective antioxidants during heavy metal poisoning; they exhibit higher bioavailability in mammals than inorganic ones and they are able to activate antioxidant defense, bind heavy metal ions and reactive oxygen species formed during metal-induced oxidative stress. One of promising organoselenium compounds is diacetophenonyl selenide (DAPS-25), which is characterized by antioxidant and antitoxic activity, under conditions including heavy metal intoxication.

  2. CAX-ing a wide net: Cation/H(+) transporters in metal remediation and abiotic stress signalling

    Science.gov (United States)

    Cation/proton exchangers (CAXs) are a class of secondary energised ion transporter that are being implicated in an increasing range of cellular and physiological functions. CAXs are primarily Ca(2+) efflux transporters that mediate the sequestration of Ca(2+) from the cytosol, usually into the vacuo...

  3. Synthesis and characterization of a new inorganic cation-exchanger-Zr(IV) tungstomolybdate: Analytical applications for metal content determination in real sample and synthetic mixture

    International Nuclear Information System (INIS)

    An amorphous sample of inorganic cation-exchanger Zr(IV) tungstomolybdate was prepared by mixing varying ratios of 0.1 M aqueous solution of sodium tungstate and 0.1 M aqueous solution of sodium molybdate into 0.1 M aqueous solution of zirconium oxychloride at pH 1. This cation-exchanger was found to have a good ion-exchange capacity (2.40 mequiv. g-1 for Na+), high thermal and chemical stability. A tentative structural formula was proposed on the basis of chemical composition, FTIR and thermogravimetric analysis. Distribution coefficients (K d) values of metal ions in various solvent systems were determined. Some important and analytically difficult quantitative binary separations viz. Ni(II)-Pb(II), Ni(II)-Zn(II), Ni(II)-Cd(II), Mg(II)-Al(III), etc. were achieved. The practical applicability of the cation-exchanger was demonstrated in the separation of Cu(II)-Zn(II) from a synthetic mixture as well as from real samples of pharmaceutical formulation and brass alloy

  4. Detection of heavy metals in biological samples through anodic stripping voltammetry

    OpenAIRE

    Buzea, Vlad; Florescu, Monica; Badea, Mihaela

    2012-01-01

    The toxicological aspects due to the presence of heavy metals in biological samples impose to have accurate and rapid methods for their detection. This paper is aimed to review approaches to anodic stripping voltammetry (ASV) determination of several heavy metals (lead, cadmium, copper, mercury, zinc) in biological matrices (blood, urine, saliva, tissue sample). Analytical performances (LOD, data linearity range, sensitivity) of the reviewed methods were presented for several electrochemical ...

  5. Biological significance of metals partitioned to subcellular fractions within earthworms (Aporrectodea caliginosa).

    NARCIS (Netherlands)

    Vijver, Martina G; Gestel, Cornelis A M van; Straalen, Nico M van; Lanno, Roman P; Peijnenburg, Willie J G M

    2006-01-01

    Metal ions in excess of metabolic requirements are potentially toxic and must be removed from the vicinity of important biological molecules to protect organisms from adverse effects. Correspondingly, metals are sequestrated in various forms, defining the accumulation pattern and the magnitude of st

  6. [Design and synthesis of imine compound for metal cation logical gates recognition and setup of double-control fluorescent molecule switch].

    Science.gov (United States)

    Huang, Tao; Zhu, Yu-lian; Dai, Xue-qin; Zhang, Qi; Huang, Yan

    2011-07-01

    The Schiff base's reduced product N,N-bis(4-methoxybenzyl) ethane-1,2-diamine, which was used as a receptor L, was designed and synthesized for the first time in the present article. It was found that Cu2+ and Fe3+ could quench L in fluorescence observably and Zn2+ and Cd2+ could enhance L remarkably. So the two pair metal cation could set up "OR" logical gate relation with the receptor molecule L, then a logical recognition system be formed. The data of resolved ZnL's single crystal indicated that ZnL belonged to monoclinic (CCDC No. 747994). Integrated spectrum instrument was used to characterize the structure of its alike series of complex compound. According to ZnL's excellent fluorescence character and the ability to exchange with contiguous metal cation, ZnZ+/ZnL/Co2+, Zn2+/ZnL/Nit+ fluorescent molecule switch was designed. It is hoped that the work above could be positive for the development of molecule computer, bio-intellectualized inspection technology (therapy) and instrument.

  7. [Design and synthesis of imine compound for metal cation logical gates recognition and setup of double-control fluorescent molecule switch].

    Science.gov (United States)

    Huang, Tao; Zhu, Yu-lian; Dai, Xue-qin; Zhang, Qi; Huang, Yan

    2011-07-01

    The Schiff base's reduced product N,N-bis(4-methoxybenzyl) ethane-1,2-diamine, which was used as a receptor L, was designed and synthesized for the first time in the present article. It was found that Cu2+ and Fe3+ could quench L in fluorescence observably and Zn2+ and Cd2+ could enhance L remarkably. So the two pair metal cation could set up "OR" logical gate relation with the receptor molecule L, then a logical recognition system be formed. The data of resolved ZnL's single crystal indicated that ZnL belonged to monoclinic (CCDC No. 747994). Integrated spectrum instrument was used to characterize the structure of its alike series of complex compound. According to ZnL's excellent fluorescence character and the ability to exchange with contiguous metal cation, ZnZ+/ZnL/Co2+, Zn2+/ZnL/Nit+ fluorescent molecule switch was designed. It is hoped that the work above could be positive for the development of molecule computer, bio-intellectualized inspection technology (therapy) and instrument. PMID:21942034

  8. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system,which has been viewed as a new kind of binding force,as being compared with the classical interactions(e.g. hydrogen bonding,electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper,we present an overview of the typical cation-π interactions in biological systems,the experimental and theoretical investigations on cation-π interactions,as well as the research results on cation-π interactions in our group.

  9. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    CHENG JiaGao; LUO XiaoMin; YAN XiuHua; LI Zhong; TANG Yun; JIANG HuaLiang; ZHU WeiLiang

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system, which has been viewed as a new kind of binding force, as being compared with the classical interac-tions (e.g. hydrogen bonding, electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper, we present an overview of the typi-cal cation-π interactions in biological systems, the experimental and theoretical investigations on cation-π interactions, as well as the research results on cation-π interactions in our group.

  10. Green Synthesis of Metallic Nanoparticles via Biological Entities

    Directory of Open Access Journals (Sweden)

    Monaliben Shah

    2015-10-01

    Full Text Available Nanotechnology is the creation, manipulation and use of materials at the nanometre size scale (1 to 100 nm. At this size scale there are significant differences in many material properties that are normally not seen in the same materials at larger scales. Although nanoscale materials can be produced using a variety of traditional physical and chemical processes, it is now possible to biologically synthesize materials via environment-friendly green chemistry based techniques. In recent years, the convergence between nanotechnology and biology has created the new field of nanobiotechnology that incorporates the use of biological entities such as actinomycetes algae, bacteria, fungi, viruses, yeasts, and plants in a number of biochemical and biophysical processes. The biological synthesis via nanobiotechnology processes have a significant potential to boost nanoparticles production without the use of harsh, toxic, and expensive chemicals commonly used in conventional physical and chemical processes. The aim of this review is to provide an overview of recent trends in synthesizing nanoparticles via biological entities and their potential applications.

  11. Design and Synthesis of Redox-Switched Lariat Ethers and Their Application for Transport of Alkali and Alkaline-Earth Metal Cations Across Supported Liquid Membrane

    Directory of Open Access Journals (Sweden)

    Uma Sharma

    2006-08-01

    Full Text Available A new class of redox-switched anthraquinone derived lariat ethers 1-(1-anthraquinonyloxy 3, 6, 9 trioxaundecane 11-ol (M1, 1-(1-anthraquinonyloxy 3, 6 dioxaoctane 9-ol (M2, 1-(1-anthraquinonyloxy 3 oxapentane 5-ol (M3, 1-(1-anthraquinonyloxy 3 oxapentane 5-butane (M4, 1-(1-anthraquinonyloxy 3, 6 dioxaoctane 9-methane (M5 and 1-(1-anthraquinonyloxy 3 oxapentane 5-methane (M6 have been synthesized and characterized by spectral analysis. These ionophores were used in liquid membrane carrier facilitated transport of main group metal cations across supported liquid membrane (SLM. Cellulose nitrate membrane was used as membrane support. Effect of various parameters such as variation in concentration of metal as well as ionophore, effect of chain length and end group of ionophore have been studied. The sequence of metal ions transported by ionophore M1 is Na+ > Li+ > K+ > Ca2+ > Mg2+ and the order of metal ions transported by ionophores (M2–M6 is Li+ > Na+ > K+ > Ca2+ > Mg2+. Ionophore M1 is selective for Na+, Li+, and K+ and ionophores (M2–M6 are selective for Li+ and Na+.

  12. Improvement of heavy metal biosorption by mycelial dead biomasses (Rhizopus arrhizus, Mucor miehei and Penicillium chrysogenum): pH control and cationic activation.

    Science.gov (United States)

    Fourest, E; Canal, C; Roux, J C

    1994-08-01

    Fungal mycelial by-products from fermentation industries present a considerable affinity for soluble metal ions (e.g. Zn, Cd, Ni, Pb, Cr, Ag) and could be used in biosorption processes for purification of contaminated effluents. In this work the influence of pH on sorption parameters is characterized by measuring the isotherms of five heavy metals (Ni, Zn, Cd, Ag and Pb) with Rhizopus arrhizus biomass under pH-controlled conditions. The maximum sorption capacity for lead was observed at pH 7.0 (200 mg g-1), while silver uptake was weakly affected. The stability of metal-biosorbent complexes is regularly enhanced by pH neutralization, except for lead. A transition in sorption mechanism was observed above pH 6.0. In addition, comparison of various industrial fungal biomasses (R. arrhizus, Mucor miehei and Penicillium chrysogenum) indicated important variations in zinc-binding and buffering properties (0.24, 0.08 and 0.05 mmol g-1, respectively). Without control, the equilibrium pH (5.8, 3.9 and 4.0) is shown to be related to the initial calcium content of the biosorbent. pH neutralization during metal adsorption increases zinc sorption in all fungi (0.57, 0.52 and 0.33 mmol g-1) but an improvement was also obtained (0.34, 0.33 and 0.10 mmol g-1) by calcium saturation of the biomass before heavy metal accumulation. Breakthrough curves of fixed bed biosorbent columns demonstrated the capacity of the biosorbent process to purify zinc and lead solutions in continuous-flow systems, and confirmed the necessity for cationic activation of the biosorbent before contact with the heavy-metal solution.

  13. Biological removal of metal ions from aqueous process streams

    International Nuclear Information System (INIS)

    Aqueous waste streams from nuclear fuel processing operations may contain trace quantities of heavy metals such as uranium. Conventional chemical and physical treatment may be ineffective or very expensive when uranium concentrations in the range of 10 to 100 g/m3 must be reduced to 1 g/m3 or less. The ability of some microorganisms to adsorb or complex dissolved heavy metals offers an alternative treatment method. Uranium uptake by Saccharomyces cerevisiae NRRL Y-2574 and a strain of Pseudomonas aeruginosa was examined to identify factors which might affect a process for the removal of uranium from wastewater streams. At uranium concentrations in the range of 10 to 500 g/m3, where the binding capacity of the biomass was not exceeded, temperature, pH, and initial uranium concentration were found to influence the rate of uranium uptake, but not the soluble uranium concentration at equilibrium. 6 figs

  14. Chemical and biological extraction of metals present in E waste: A hybrid technology

    International Nuclear Information System (INIS)

    Highlights: ► Hybrid methodology for E waste management. ► Efficient extraction of metals. ► Trace metal extraction is possible. - Abstract: Management of metal pollution associated with E-waste is widespread across the globe. Currently used techniques for the extraction of metals from E-waste by using either chemical or biological leaching have their own limitations. Chemical leaching is much rapid and efficient but has its own environmental consequences, even the future prospects of associated nanoremediation are also uncertain. Biological leaching on the other hand is comparatively a cost effective technique but at the same moment it is time consuming and the complete recovery of the metal, alone by biological leaching is not possible in most of the cases. The current review addresses the individual issues related to chemical and biological extraction techniques and proposes a hybrid-methodology which incorporates both, along with safer chemicals and compatible microbes for better and efficient extraction of metals from the E-waste.

  15. The structural diversity of DNA-neutral phospholipids-divalent metal cations aggregates: a small-angle synchrotron X-ray diffraction study.

    Science.gov (United States)

    Uhríková, Daniela; Lengyel, Adrián; Hanulová, Mária; Funari, Sérgio S; Balgavý, Pavol

    2007-04-01

    We investigate the structure of aggregates formed due to DNA interaction with saturated neutral phosphatidylcholines [dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine] in presence of Ca(2+) and Mg(2+) cations using simultaneous synchrotron small- and wide-angle X-ray diffractions. For DPPC:DNA = 3:1 mol/base and in the range of 1-50 mM Ca(2+), the diffractograms show structural heterogeneity of aggregates. We observe the coexistence of two lamellar phases in aggregates prepared at 1 mM Ca(2+): L(x) phase with the DNA strands (of unknown organization) intercalated in water layers between adjacent lipid bilayers and L(DPPC) phase of DPPC bilayers without any divalent cations and DNA strands. Aggregates prepared in the range 2-50 mM Ca(2+) show a condensed gel lamellar phase L (g) (c) with the lipid bilayer periodicity d approximately 8.0 nm, and the DNA-DNA interhelical distance d (DNA) approximately 5.1 nm. The increase of temperature induces the decrease in the intensity and the increase in the width of the DNA related peak. In the fluid state, the condensed lamellar phase L (alpha) (c) gradually converts into L(x) phase. The aggregates do not exhibit rippled P(beta) phase. The thermal behaviour of aggregates was investigated in the range 20-80 degrees C. Applying heating-cooling cycles, the aggregates converted into energetically more favourable structure: a condensed lamellar phase L(c) (or L(x)) is preserved or we observe lateral segregation of the DNA strands and metal cations (L(x) phase) in coexistence with L(PC) phase of pure phospholipids. PMID:16865363

  16. Mitigation of heavy metals in different vegetables through biological washing techniques

    Directory of Open Access Journals (Sweden)

    Muhammad Umair Sattar

    2015-12-01

    Full Text Available Availability of nutritious and healthy food is the foremost challenging issue in all over the word. Vegetables are essential part in human diet and considered as natural reserves of nutrients gifted by Almighty Allah to human beings. Heavy metals are among the most toxic food pollutants and their intake through diet leads to several disorders. The sources of heavy metal contamination include waste water irrigation, industrial emissions, transportation and application of metal-based pesticides. In Pakistan this situation is more alarming as vegetables grown in peri-urban areas have shown high incidence of heavy metals accumulation. In this study effort was made to mitigate different heavy metals (Ar, Cd, Cr and Pb in cauliflower, spinach, okra and brinjal collected from peri-urban areas through washing with different biological solutions. Heavy metals contents were determined by using Atomic Absorption Spectrophotometry (AAS. Vegetable showed high load of heavy metals in unwashed form that reduced significantly by washing with different biological solutions. Among the different biological solutions, washing of vegetables with 8% ginger solution was found to be more effective.

  17. Nanometallomics: an emerging field studying the biological effects of metal-related nanomaterials.

    Science.gov (United States)

    Li, Yu-Feng; Gao, Yuxi; Chai, Zhifang; Chen, Chunying

    2014-02-01

    Metallomics, focusing on the global and systematic understanding of the metal uptake, trafficking, role and excretion in biological systems, has attracted more and more attention. Metal-related nanomaterials, including metallic and metal-containing nanomaterials, have unique properties compared to their micro-scaled counterparts and therefore require special attention. The small size effect, surface effect, and quantum size effect directly influence the physicochemical properties of nanostructured materials and their fate and behavior in biota. However, to our knowledge, the metallomics itself did not touch this special category of materials yet. Therefore, the term "nanometallomics" is proposed and the systematic study on the absorption, distribution, metabolism, excretion (ADME) behavior of metal-related nanomaterials in biological systems and their interactions with genes, proteins and other biomolecules will be reviewed. The ADME behavior of metal-related nanomaterials in the biological systems is influenced by their physicochemical properties, the exposure route, and the microenvironment of the deposition site. Nanomaterials may not only interact directly or indirectly with genes, proteins and other molecules to cause DNA damage, genotoxicity, immunotoxicity, and cytotoxicity, but also stimulate the immune responses, circumvent tumor resistance and inhibit tumor metastasis. Nanometallomics needs to be integrated with other omics sciences, such as genomics, proteomics and metabolomics, to explore the biomedical data and obtain the overall knowledge of underlying mechanisms, and therefore to improve the application performance and to reduce the potential risk of metal-related nanomaterials.

  18. Interaction of metallic clusters with biologically active curcumin molecules

    Science.gov (United States)

    Gupta, Sanjeev K.; He, Haiying; Liu, Chunhui; Dutta, Ranu; Pandey, Ravindra

    2015-09-01

    We have investigated the interaction of subnano metallic Gd and Au clusters with curcumin, an important biomolecule having pharmacological activity. Gd clusters show different site preference to curcumin and much stronger interaction strength, in support of the successful synthesis of highly stable curcumin-coated Gd nanoparticles as reported recently. It can be attributed to significant charge transfer from the Gd cluster to curcumin together with a relatively strong hybridization of the Gd df-orbitals with curcumin p-orbitals. These results suggest that Gd nanoparticles can effectively be used as delivery carriers for curcumin at the cellular level for therapy and medical imaging applications.

  19. Heavy metals removal in wastewater by activated carbon adsorption and clays of cationic interchange; Eliminacion de metales pesados en disolucion mediante adsorcion en carbon activo y arcillas de intercambio cationico

    Energy Technology Data Exchange (ETDEWEB)

    Montes, M. A.; Medialdea, J. M.; Garcia Mediavilla, B.; Moron, M. J.; Arnaiz, M. C.; Garcia Martinez de Simon, I.; Lopez, C. M.; Escot, E.; Lebrato, J. [Universidad de Sevilla. Sevilla (Spain)

    1999-11-01

    Among the different treatment systems assessed for the purification of the wastewaters poured from Aznalcollar quarry the last April 25, 1998, physical and chemical adsorption proved highly efficient for the removal of refractory heavy metals. In laboratory experiments, 99% of dissolved Mn and Zn was removed when wastewater passed through a packedbed column filled with a cationic exchange clay. In the same way, activated-carbon adsorption removed more than 80% of dissolved Zn and 11-16% of Mn. Results confirm the feasibility of these processes and contribute knowledge on their operational characteristics so that in any other similar situation we can consider all treatment possibilities. 8 refs.

  20. CATION EXCHANGER1 Cosegregates with Cadmium Tolerance in the Metal Hyperaccumulator Arabidopsis halleri and Plays a Role in Limiting Oxidative Stress in Arabidopsis Spp.

    Science.gov (United States)

    Baliardini, Cecilia; Meyer, Claire-Lise; Salis, Pietrino; Saumitou-Laprade, Pierre; Verbruggen, Nathalie

    2015-09-01

    Arabidopsis halleri is a model species for the study of plant adaptation to extreme metallic conditions. In this species, cadmium (Cd) tolerance seems to be constitutive, and the mechanisms underlying the trait are still poorly understood. A previous quantitative trait loci (QTL) analysis performed on A. halleri × Arabidopsis lyrata backcross population1 identified the metal-pump gene Heavy Metal ATPase4 as the major genetic determinant for Cd tolerance. However, although necessary, Heavy Metal ATPase4 alone is not sufficient for determining this trait. After fine mapping, a gene encoding a calcium(2+)/hydrogen(+) antiporter, cation/hydrogen(+) exchanger1 (CAX1), was identified as a candidate gene for the second QTL of Cd tolerance in A. halleri. Backcross population1 individuals displaying the A. halleri allele for the CAX1 locus exhibited significantly higher CAX1 expression levels compared with the ones with the A. lyrata allele, and a positive correlation between CAX1 expression and Cd tolerance was observed. Here, we show that this QTL is conditional and that it is only detectable at low external Ca concentration. CAX1 expression in both roots and shoots was higher in A. halleri than in the close Cd-sensitive relative species A. lyrata and Arabidopsis thaliana. Moreover, CAX1 loss of function in A. thaliana led to higher Cd sensitivity at low concentration of Ca, higher sensitivity to methylviologen, and stronger accumulation of reactive oxygen species after Cd treatment. Overall, this study identifies a unique genetic determinant of Cd tolerance in the metal hyperaccumulator A. halleri and offers a new twist for the function of CAX1 in plants. PMID:26162428

  1. CATION EXCHANGER1 Cosegregates with Cadmium Tolerance in the Metal Hyperaccumulator Arabidopsis halleri and Plays a Role in Limiting Oxidative Stress in Arabidopsis Spp.1[OPEN

    Science.gov (United States)

    Baliardini, Cecilia; Meyer, Claire-Lise; Salis, Pietrino; Saumitou-Laprade, Pierre; Verbruggen, Nathalie

    2015-01-01

    Arabidopsis halleri is a model species for the study of plant adaptation to extreme metallic conditions. In this species, cadmium (Cd) tolerance seems to be constitutive, and the mechanisms underlying the trait are still poorly understood. A previous quantitative trait loci (QTL) analysis performed on A. halleri × Arabidopsis lyrata backcross population1 identified the metal-pump gene Heavy Metal ATPase4 as the major genetic determinant for Cd tolerance. However, although necessary, Heavy Metal ATPase4 alone is not sufficient for determining this trait. After fine mapping, a gene encoding a calcium2+/hydrogen+ antiporter, cation/hydrogen+ exchanger1 (CAX1), was identified as a candidate gene for the second QTL of Cd tolerance in A. halleri. Backcross population1 individuals displaying the A. halleri allele for the CAX1 locus exhibited significantly higher CAX1 expression levels compared with the ones with the A. lyrata allele, and a positive correlation between CAX1 expression and Cd tolerance was observed. Here, we show that this QTL is conditional and that it is only detectable at low external Ca concentration. CAX1 expression in both roots and shoots was higher in A. halleri than in the close Cd-sensitive relative species A. lyrata and Arabidopsis thaliana. Moreover, CAX1 loss of function in A. thaliana led to higher Cd sensitivity at low concentration of Ca, higher sensitivity to methylviologen, and stronger accumulation of reactive oxygen species after Cd treatment. Overall, this study identifies a unique genetic determinant of Cd tolerance in the metal hyperaccumulator A. halleri and offers a new twist for the function of CAX1 in plants. PMID:26162428

  2. Challenge to assess the toxic contribution of metal cation released from nanomaterials for nanotoxicology - the case of ZnO nanoparticles

    Science.gov (United States)

    Xu, Mingsheng; Li, Jie; Hanagata, Nobutaka; Su, Huanxing; Chen, Hongzheng; Fujita, Daisuke

    2013-05-01

    The identification of physicochemical factors that govern toxic effects of nanomaterials (NMs) is important for the safe design and synthesis of NMs. The release of metal cations from NMs in cell culture medium and the role of the metal cations in cytotoxicity are still under dispute. Here, we report that removal of NMs such as ZnO nanoparticles (NPs) by centrifugation, the procedure commonly used for the estimation of released ion concentration in nanotoxicology, was incomplete even at a relative centrifugal force of 150 000 × g. In this sense, the Zn concentration in supernatant measured by inductively coupled plasma-mass spectrometry cannot be regarded as the concentration of free Zn2+ ions which were released from ZnO NPs in cell culture medium. This suggests the urgent need to develop relevant analytical techniques for nanotoxicology. The toxic contribution of released Zn2+ ions to the A549 cell lines was estimated to be only about 10%. We conclude that the cytotoxicity associated with ZnO NPs is not a function of the Zn concentration, suggesting that other factors play an important role in the toxic effect of ZnO NPs.The identification of physicochemical factors that govern toxic effects of nanomaterials (NMs) is important for the safe design and synthesis of NMs. The release of metal cations from NMs in cell culture medium and the role of the metal cations in cytotoxicity are still under dispute. Here, we report that removal of NMs such as ZnO nanoparticles (NPs) by centrifugation, the procedure commonly used for the estimation of released ion concentration in nanotoxicology, was incomplete even at a relative centrifugal force of 150 000 × g. In this sense, the Zn concentration in supernatant measured by inductively coupled plasma-mass spectrometry cannot be regarded as the concentration of free Zn2+ ions which were released from ZnO NPs in cell culture medium. This suggests the urgent need to develop relevant analytical techniques for nanotoxicology. The

  3. Evaluation of Iron Nickel Oxide Nanopowder as Corrosion Inhibitor: Effect of Metallic Cations on Carbon Steel in Aqueous NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhry, A. U.; Mishra, Brajendra [Colorado School of Mines, Denver (United States); Mittal, Vikas [The Petroleum Institute, Abu Dhabi (United Arab Emirates)

    2016-01-15

    The aim of this study was to evaluate the use of iron-nickel oxide (Fe{sub 2}O{sub 3}.NiO) nanopowder (FeNi) as an anti-corrosion pigment for a different application. The corrosion protection ability and the mechanism involved was determined using aqueous solution of FeNi prepared in a corrosive solution containing 3.5 wt.% NaCl. Anti-corrosion abilities of aqueous solution were determined using electrochemical impedance spectroscopy (EIS) on line pipe steel (API 5L X-80). The protection mechanism involved the adsorption of metallic cations on the steel surface forming a protective film. Analysis of EIS spectra revealed that corrosion inhibition occurred at low concentration, whereas higher concentration of aqueous solution produced induction behavior.

  4. A study on equilibrium and kinetics of ion exchange of alkaline earth metals using an inorganic cation exchanger - zirconium titanium phosphate

    Indian Academy of Sciences (India)

    Amin Jignasa; Thakkar Rakesh; Chudasama Uma

    2006-03-01

    An advanced inorganic cation exchange material of the class of tetravalent metal acid (TMA) salt, zirconium titanium phosphate (ZTP), has been synthesized by a modified sol-gel technique. ZTP has been characterized by elemental analysis (ICP-AES), thermal analysis (TGA), FTIR and X-ray diffraction studies. The Nernst-Planck equation has been used to study the forward and reverse ion exchange kinetics of Mg (II), Ca (II), Sr (II) and Ba (II) with H (I) at four different temperatures. The mechanism of exchange is particle diffusion, as confirmed by the linear (dimensionless time parameter) vs (time) plots. The exchange process is thus controlled by the diffusion within the exchanger particles for the systems studied herein. Further, various kinetic parameters like self-diffusion coefficient (0), energy of activation () and entropy of activation (*) have been evaluated under conditions favouring a particle diffusion-controlled mechanism.

  5. 阳离子树脂净化铂族金属溶液的研究%Purification of Platinum Group Metals Solution by Cation Exchange

    Institute of Scientific and Technical Information of China (English)

    毕向光; 余建民; 杨金富; 贺洪亮; 李权

    2015-01-01

    研究了阳离子交换树脂净化含大量贱金属的铂族金属溶液的工艺条件,结果表明,在pH=1~1.5时001×7阳离子交换树脂吸附贱金属的次序为:Ni>Cu>Co>Fe;Fe、Ni、Co、Cu的穿透容量分别为(g/kg):0.13,1.25,0.42,0.87;饱和容量分别为(g/kg):0.32,6.65,2.33,4.72,合计为14.02 g/kg;贱金属的分离效率主要取决于贵贱金属浓度及交换柱的数量;吸附在树脂上的贱金属极易被6 mol/L HCl洗脱,所有贱金属的最大洗脱均发生在洗脱液体积与床体积之比为1.0/1.7处,当洗脱液体积为床体积的2.0倍时贱金属被完全洗脱。实验结果为离子交换分离贱金属净化铂族金属溶液的工业化应用提供了强有力的理论依据。%The platimum group metals ( PGMs) solution containing a large amount of base metals purified with cation exchange resin had been investigated. The results showed that the adsorption of base metals by 001 × 7 cation ion exchange resin at pH=1~1.5 was in the order of Ni>Cu>Co>Fe. From the tests, the breakthrough capacities ( g/kg) of Fe, Ni, Co and Cu were 0.13, 1.25, 0.42 and 0.87, respectively, while the saturated capacities ( g/kg) were 0.32, 6.65, 2.33 and 4.72, respectively and 14.02 g/kg in total. It is shown that the separation efficiency of the base metals depends largely on the concentrations of the precious and base metals, as well as the number of exchange columns. The base metals absorbed on the resin could be easily eluted by adding HCl solution at the amount of 6 mol/L, with the elution reaching the maximum as the eluent volume and bed volume at the ratio of 1.0/1.7 and completely finished as the eluent volume being 2. 0 times the bed volume. The experimental results can definitely provide a theoretical basis favorably for the industrial application of PGMs solution purified by cation exchange resin.

  6. Whole genome duplication and enrichment of metal cation transporters revealed by de novo genome sequencing of extremely halotolerant black yeast Hortaea werneckii.

    Directory of Open Access Journals (Sweden)

    Metka Lenassi

    Full Text Available Hortaea werneckii, ascomycetous yeast from the order Capnodiales, shows an exceptional adaptability to osmotically stressful conditions. To investigate this unusual phenotype we obtained a draft genomic sequence of a H. werneckii strain isolated from hypersaline water of solar saltern. Two of its most striking characteristics that may be associated with a halotolerant lifestyle are the large genetic redundancy and the expansion of genes encoding metal cation transporters. Although no sexual state of H. werneckii has yet been described, a mating locus with characteristics of heterothallic fungi was found. The total assembly size of the genome is 51.6 Mb, larger than most phylogenetically related fungi, coding for almost twice the usual number of predicted genes (23333. The genome appears to have experienced a relatively recent whole genome duplication, and contains two highly identical gene copies of almost every protein. This is consistent with some previous studies that reported increases in genomic DNA content triggered by exposure to salt stress. In hypersaline conditions transmembrane ion transport is of utmost importance. The analysis of predicted metal cation transporters showed that most types of transporters experienced several gene duplications at various points during their evolution. Consequently they are present in much higher numbers than expected. The resulting diversity of transporters presents interesting biotechnological opportunities for improvement of halotolerance of salt-sensitive species. The involvement of plasma P-type H⁺ ATPases in adaptation to different concentrations of salt was indicated by their salt dependent transcription. This was not the case with vacuolar H⁺ ATPases, which were transcribed constitutively. The availability of this genomic sequence is expected to promote the research of H. werneckii. Studying its extreme halotolerance will not only contribute to our understanding of life in hypersaline

  7. Tautomeric switching and metal-cation sensing of ligand-equipped 4-hydroxy-/4-oxo-1,4-dihydroquinolines.

    Science.gov (United States)

    Todorov, Aleksandar R; Nieger, Martin; Helaja, Juho

    2012-06-01

    Novel 4-hydroxyquinoline (4HQ) based tautomeric switches are reported. 4HQs equipped with coordinative side arms (8-arylimino and 3-piperidin-1-ylmethyl groups) were synthesized to access O- or N-selective chelation of Zn(2+) and Cd(2+) ions by 4HQ. In the case of the monodentate arylimino group, O chelation of metal ions induces concomitant switching of phenol tautomer to the keto form in nonpolar or aprotic media. This change is accompanied by selective and highly sensitive fluorometric sensing of Zn(2+) ions. In the case of the bidentate 8-(quinolin-8-ylimino)methyl side arm, NMR studies in CD(3) OD indicated that both Cd(2+) and Zn(2+) ions afford N chelation for 4HQ, coexisting with tautomeric switching from quinolin-4(1H)-one to quinolin-4-olate. In corroboration, UV/Vis-monitored metal-ion titrations in toluene and methanol implied similar structural changes. Additionally, fluorescence measurements indicated that the metal-triggered tautomeric switching is associated with compound signaling properties. The results are supported by DFT calculations at the B3LYP 6-31G* level. Several X-ray structures of metal-free and metal-chelating 4HQ are presented to support the solution studies.

  8. Surface coating affects behavior of metallic nanoparticles in a biological environment

    Science.gov (United States)

    Jurašin, Darija Domazet; Ćurlin, Marija; Capjak, Ivona; Crnković, Tea; Lovrić, Marija; Babič, Michal; Horák, Daniel; Gajović, Srećko

    2016-01-01

    Summary Silver (AgNPs) and maghemite, i.e., superparamagnetic iron oxide nanoparticles (SPIONs) are promising candidates for new medical applications, which implies the need for strict information regarding their physicochemical characteristics and behavior in a biological environment. The currently developed AgNPs and SPIONs encompass a myriad of sizes and surface coatings, which affect NPs properties and may improve their biocompatibility. This study is aimed to evaluate the effects of surface coating on colloidal stability and behavior of AgNPs and SPIONs in modelled biological environments using dynamic and electrophoretic light scattering techniques, as well as transmission electron microscopy to visualize the behavior of the NP. Three dispersion media were investigated: ultrapure water (UW), biological cell culture medium without addition of protein (BM), and BM supplemented with common serum protein (BMP). The obtained results showed that different coating agents on AgNPs and SPIONs produced different stabilities in the same biological media. The combination of negative charge and high adsorption strength of coating agents proved to be important for achieving good stability of metallic NPs in electrolyte-rich fluids. Most importantly, the presence of proteins provided colloidal stabilization to metallic NPs in biological fluids regardless of their chemical composition, surface structure and surface charge. In addition, an assessment of AgNP and SPION behavior in real biological fluids, rat whole blood (WhBl) and blood plasma (BlPl), revealed that the composition of a biological medium is crucial for the colloidal stability and type of metallic NP transformation. Our results highlight the importance of physicochemical characterization and stability evaluation of metallic NPs in a variety of biological systems including as many NP properties as possible. PMID:26977382

  9. Quantitative investigations of cation complexation of photochromic 8-benzothiazole-substituted benzopyran: towards metal-ion sensors.

    Science.gov (United States)

    Zakharova, Marianna I; Coudret, Christophe; Pimienta, Véronique; Micheau, Jean Claude; Delbaere, Stéphanie; Vermeersch, Gaston; Metelitsa, Anatoly V; Voloshin, Nikolai; Minkin, Vladimir I

    2010-02-01

    The photochromic, thermochromic and metallochromic behaviour of a series of three spiro[indoline-8-(benzothiazol-2-yl)-benzopyrans] has been investigated. The thermodynamic and kinetic parameters of their thermal equilibrium between the ring-closed (spiro) and ring-opened (merocyanine) isomeric forms have been determined using UV-Vis absorption and (1)H NMR spectroscopies. By adding Co(ii) and Ni(ii) ions in acetonitrile solution, 1 : 1 and 1 : 2 metal : merocyanine complexes are formed simultaneously. Using appropriate numerical methods, the kinetic analysis of the complexation allowed us to determine accurately key thermodynamic and spectroscopic parameters of the metal complexes. Results showed that the complexation strength is very sensitive to the size of the indoline nitrogen substituent. Complexation can be reversed by shining white light on the coloured complexes which regenerates the inactive spiropyran form, and releases the metallic ion; hence, these systems display fully reversible negative photochromism. The Zn(ii) complexes exhibit intense fluorescence in the 600-800 nm wavelength range. All these behaviours make these spiropyrans bearing benzothiazole heterocycles promising building blocks for the future construction of photodynamic chemosensors for transition metal ions. PMID:20126795

  10. Study of the Complexation Behavior of Calixarene with Transition Metal Cations by UV-vis and Fluorescent Spectra

    Institute of Scientific and Technical Information of China (English)

    YANG,Jun-Lin(杨俊林); ZHENG,Qi-Yu(郑企雨); AN,Li-Na(安丽娜); CHEN,Chuan-Feng(陈传峰); LIN,Hong-Zhen(蔺洪振); BAI,Feng-Lian(白凤莲); HUANG,Zhi-Tang(黄志镗)

    2002-01-01

    A new fluorescent compound based on calix[4]arene skeleton was synthesized. Its complexation ability with transition metal ions, such as Fe3+, Co2+, Ni2+, Cu2+, Zn2+ and Ag+, was investigated by UV-vis and fluorescent spectra.

  11. Study of the Complexation Behavior of Calixarene with Transition Metal Cations by UV—vis and Fluorescent Spectra

    Institute of Scientific and Technical Information of China (English)

    杨俊林; 郑企雨; 等

    2002-01-01

    A new fluorescent compound based on calix[4] arene skeleton was synthesized.Its complexation ability with transition metal ions,such as Fe3+,Co2+,Ni2+,Cu2+,Zn2+ and Ag+,Was investigated by UV-vis and fluorescent spectra.

  12. Interactions between metal cations with H2 in the M+- H2 complexes: Performance of DFT and DFT-D methods

    Indian Academy of Sciences (India)

    Srimanta Pakhira; Tanay Debnath; Kaushik Sen; Abhijit K Das

    2016-04-01

    The interactions between metal cations (Ni+, Cu+, Zn+) and H2 molecule have been investigated in detail using dispersion-corrected and -uncorrected double hybrid density functional (DHDF), gradient corrected density functional, ordinary density functional and CCSD(T) methods in conjunction with the correlation consistent triple- quality basis sets. Structural properties, depth of the potential well and dissociation energies are calculated using DFT, DFT-D and CCSD(T) methods and are compared with experimental results. A comparative analysis has been made among DFT, DFT-D and CCSD(T) methods with respect to experiments. The energy components of the interaction energy have been estimated by the symmetry-adapted perturbation theory (SAPT) to analyze the effect of various components on the interaction of the complexes. The dispersion-corrected DHDF, mPW2PLYP-D method shows the best agreement with the experimental values. An NBO analysis has been performed to understand the orbital participation in metal ligand interaction and charge transfer process in these complexes.

  13. Zeolite-type metal organic frameworks immobilized Eu³⁺ for cation sensing in aqueous environment.

    Science.gov (United States)

    Liu, Chang; Yan, Bing

    2015-12-01

    A novel luminescent lanthanide metal organic framework (Ln-MOF) is synthesized by in situ encapsulating Eu(3+) ions to partial replace the transition-metal clusters in the channels of CPM-17-Zn nanocrystals. The Eu(3+) functionalized zeolite-type MOF hybrid system shows excellent luminescence property and photo-stability in aqueous environment for the sensitization and protection from the host framework. Subsequently, as a highly selective and sensitive sensor, its nanocrystals can be used to detect Cd(2+) in aqueous solution. In addition, the possible sensing mechanism based on ion exchange is discussed in detail. This work is one of the few cases for detecting Cd(2+) in aqueous solution based on a zeolite-type MOF. The good fluorescence stability, low detection limit and broad linear range in aqueous environment make this probe to be expected to have potential application in intracellular sensing and imaging of Cd(2+) potentially.

  14. Biological and chemical characterization of metal bioavailability in sediments from Lake Roosevelt, Columbia River, Washington, USA

    Science.gov (United States)

    Besser, J.M.; Brumbaugh, W.G.; Ivey, C.D.; Ingersoll, C.G.; Moran, P.W.

    2008-01-01

    We studied the bioavailability and toxicity of copper, zinc, arsenic, cadmium, and lead in sediments from Lake Roosevelt (LR), a reservoir on the Columbia River in Washington, USA that receives inputs of metals from an upstream smelter facility. We characterized chronic sediment toxicity, metal bioaccumulation, and metal concentrations in sediment and pore water from eight study sites: one site upstream in the Columbia River, six sites in the reservoir, and a reference site in an uncontaminated tributary. Total recoverable metal concentrations in LR sediments generally decreased from upstream to downstream in the study area, but sediments from two sites in the reservoir had metal concentrations much lower than adjacent reservoir sites and similar to the reference site, apparently due to erosion of uncontaminated bank soils. Concentrations of acid-volatile sulfide in LR sediments were too low to provide strong controls on metal bioavailability, and selective sediment extractions indicated that metals in most LR sediments were primarily associated with iron and manganese oxides. Oligochaetes (Lumbriculus variegatus) accumulated greatest concentrations of copper from the river sediment, and greatest concentrations of arsenic, cadmium, and lead from reservoir sediments. Chronic toxic effects on amphipods (Hyalella azteca; reduced survival) and midge larvae (Chironomus dilutus; reduced growth) in whole-sediment exposures were generally consistent with predictions of metal toxicity based on empirical and equilibrium partitioning-based sediment quality guidelines. Elevated metal concentrations in pore waters of some LR sediments suggested that metals released from iron and manganese oxides under anoxic conditions contributed to metal bioaccumulation and toxicity. Results of both chemical and biological assays indicate that metals in sediments from both riverine and reservoir habitats of Lake Roosevelt are available to benthic invertebrates. These findings will be used as

  15. S/G-1: an ab initio force-field blending frozen Hermite Gaussian densities and distributed multipoles. Proof of concept and first applications to metal cations.

    Science.gov (United States)

    Chaudret, Robin; Gresh, Nohad; Narth, Christophe; Lagardère, Louis; Darden, Thomas A; Cisneros, G Andrés; Piquemal, Jean-Philip

    2014-09-01

    response level. This opens up the possibility of embodying explicit scalar relativistic effects in molecular mechanics thanks to the direct transferability of ab initio pseudopotentials. Therefore, incorporating GEM-like electron density for a metal cation enable the introduction of nonambiguous short-range quantum effects within any point-dipole based polarizable force field without the need of an extensive parametrization.

  16. Metal-phosphate binders

    Science.gov (United States)

    Howe, Beth Ann [Lewistown, IL; Chaps-Cabrera, Jesus Guadalupe [Coahuila, MX

    2009-05-12

    A metal-phosphate binder is provided. The binder may include an aqueous phosphoric acid solution, a metal-cation donor including a metal other than aluminum, an aluminum-cation donor, and a non-carbohydrate electron donor.

  17. Structural, Chemical and Biological Aspects of Antioxidants for Strategies Against Metal and Metalloid Exposure

    Directory of Open Access Journals (Sweden)

    Swaran J. S. Flora

    2009-01-01

    Full Text Available Oxidative stress contributes to the pathophysiology of exposure to heavy metals/metalloid. Beneficial renal effects of some medications, such as chelation therapy depend at least partially on the ability to alleviate oxidative stress. The administration of various natural or synthetic antioxidants has been shown to be of benefit in the prevention and attenuation of metal induced biochemical alterations. These include vitamins, N-acetylcysteine, α-lipoic acid, melatonin, dietary flavonoids and many others. Human studies are limited in this regard. Under certain conditions, surprisingly, the antioxidant supplements may exhibit pro-oxidant properties and even worsen metal induced toxic damage. To date, the evidence is insufficient to recommend antioxidant supplements in subject with exposure to metals. Prospective, controlled clinical trials on safety and effectiveness of different therapeutic antioxidant strategies either individually or in combination with chelating agent are indispensable. The present review focuses on structural, chemical and biological aspects of antioxidants particularly related to their chelating properties.

  18. PIXE characterization of tissues surrounding metallic prostheses coated with biological glasses

    Energy Technology Data Exchange (ETDEWEB)

    Barbotteau, Y. E-mail: yves.barbotteau@qse.tohoku.ac.jp; Irigaray, J.L.; Moretto, Ph

    2004-01-01

    Biological glasses can be used as coatings for metallic prostheses in order to prevent corrosion. According to their composition, these glasses have different properties. We studied, in vivo, two glasses referred to as BVA and BVH. They are used as coatings of Ti6Al4V metallic implant. BVA glass disappears after 3 months of implantation and is replaced by bone. Prostheses initially coated by this glass have a larger osseous contact perimeter compared to the uncoated prostheses. This ensures a better anchoring of the implant and limits the micro-motions which cause wear debris. BVH glass keeps a constant composition during implantation and it is used like a layer which isolates metal implant from biological environment. In order to characterize the bony environment surrounding implants, we have used PIXE and RBS methods. This paper shows results of the behavior of bony tissue under micro-beam, the quality tests of new bone which replaces the BVA glass coating and the evaluation of corrosion effects. Titanium release in bony tissues begins when the metal surface of the prosthesis is exposed to biological fluids. After a few months of implantation, the titanium contamination is stabilized and remains localized within the first tens of micrometers of surrounding bone.

  19. Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water.

    Science.gov (United States)

    Alatalo, Sara-Maaria; Pileidis, Filoklis; Mäkilä, Ermei; Sevilla, Marta; Repo, Eveliina; Salonen, Jarno; Sillanpää, Mika; Titirici, Maria-Magdalena

    2015-11-25

    Hydrothermal carbonization of cellulose in the presence of the globular protein ovalbumin leads to the formation of nitrogen-doped carbon aerogel with a fibrillar continuous carbon network. The protein plays here a double role: (i) a natural source of nitrogen functionalities (2.1 wt %) and (ii) structural directing agent (S(BET) = 38 m(2)/g). The applicability in wastewater treatment, namely, for heavy metal removal, was examined through adsorption of Cr(VI) and Pb(II) ion solely and in a mixed bicomponent aqueous solutions. This cellulose-based carbogel shows an enhanced ability to remove both Cr(VI) (∼68 mg/g) and Pb(II) (∼240 mg/g) from the targeted solutions in comparison to other carbon materials reported in the literature. The presence of competing ions showed little effect on the adsorption efficiency toward Cr(VI) and Pb(II).

  20. Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water.

    Science.gov (United States)

    Alatalo, Sara-Maaria; Pileidis, Filoklis; Mäkilä, Ermei; Sevilla, Marta; Repo, Eveliina; Salonen, Jarno; Sillanpää, Mika; Titirici, Maria-Magdalena

    2015-11-25

    Hydrothermal carbonization of cellulose in the presence of the globular protein ovalbumin leads to the formation of nitrogen-doped carbon aerogel with a fibrillar continuous carbon network. The protein plays here a double role: (i) a natural source of nitrogen functionalities (2.1 wt %) and (ii) structural directing agent (S(BET) = 38 m(2)/g). The applicability in wastewater treatment, namely, for heavy metal removal, was examined through adsorption of Cr(VI) and Pb(II) ion solely and in a mixed bicomponent aqueous solutions. This cellulose-based carbogel shows an enhanced ability to remove both Cr(VI) (∼68 mg/g) and Pb(II) (∼240 mg/g) from the targeted solutions in comparison to other carbon materials reported in the literature. The presence of competing ions showed little effect on the adsorption efficiency toward Cr(VI) and Pb(II). PMID:26540557

  1. Accuracy of the DLPNO-CCSD(T) method for non-covalent bond dissociation enthalpies from coinage metal cation complexes

    KAUST Repository

    Minenkov, Yury

    2015-08-27

    The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) method has been tested to reproduce the experimental gas phase ligand dissociation enthalpy in a series of Cu+, Ag+ and Au+ complexes. For 33 Cu+ - non-covalent ligand dissociation enthalpies all-electron calculations with the same method result in MUE below 2.2 kcal/mol, although a MSE of 1.4 kcal/mol indicates systematic underestimation of the experimental values. Inclusion of scalar relativistic effects for Cu either via effective core potential (ECP) or Douglass-Kroll-Hess Hamiltonian, reduces the MUE below 1.7 kcal/mol and the MSE to -1.0 kcal/mol. For 24 Ag+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) method results in a mean unsigned error (MUE) below 2.1 kcal/mol and vanishing mean signed error (MSE). For 15 Au+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) methods provides larger MUE and MSE, equal to 3.2 and 1.7 kcal/mol, which might be related to poor precision of the experimental measurements. Overall, for the combined dataset of 72 coinage metal ion complexes DLPNO-CCSD(T) results in a MUE below 2.2 kcal/mol and an almost vanishing MSE. As for a comparison with computationally cheaper density functional theory (DFT) methods, the routinely used M06 functional results in MUE and MSE equal to 3.6 and -1.7 kca/mol. Results converge already at CC-PVTZ quality basis set, making highly accurate DLPNO-CCSD(T) estimates to be affordable for routine calculations (single-point) on large transition metal complexes of > 100 atoms.

  2. Preparation, structural characterization and biological evaluation of L-tyrosinate metal ion complexes

    Science.gov (United States)

    Refat, Moamen S.; El-Korashy, Sabry A.; Ahmed, Ahmed S.

    2008-06-01

    The complexes formed between different metal ions and biological molecules like amino acids play an important role in human life. Sn(II), Sn(IV), Zn(II), Cd(II), Hg(II), Cr(III), Fe(III), La(III), ZrO(II) and UO 2(II) complexes are synthesized with L-tyrosine (tyr). These complexes are characterized by elemental analysis, molar conductance, magnetic measurements, mass, IR, UV-vis and 1H NMR spectra as well as thermogravimetric analysis (TGA/DTG). It has been found from the elemental analysis and the thermal studies that the ligand behaves as bidentate ligand forming chelates with 1:3 (metal:ligand) stoichiometry for trivalent metals and 1:2 for divalent and tetravalent metals. The molar conductance measurements of the complexes in DMSO indicate that the complexes are non-electrolyte. The activation energies and other kinetic parameters were calculated from the Coats-Redfern and Horowitz-Metzger equations. The biological activities of the metal complexes have also been studied against different bacteria and fungi.

  3. Biological in vitro and in vivo studies of a series of new asymmetrical cationic [99mTc(N)(DTC-Ln)(PNP)]+ complex (DTC-Ln = alicyclic dithiocarbamate and PNP = diphosphinoamine).

    Science.gov (United States)

    Bolzati, Cristina; Cavazza-Ceccato, Mario; Agostini, Stefania; Refosco, Fiorenzo; Yamamichi, Yoshihiro; Tokunaga, Shinji; Carta, Davide; Salvarese, Nicola; Bernardini, Daniele; Bandoli, Giuliano

    2010-05-19

    (99m)Tc(N)-DBODC5 is a cationic mixed compound under clinical investigation as potential myocardial imaging agent. In spite of this, analogously to the other cationic (99m)Tc-agents, presents a relatively low first-pass extraction. Thus, modification of (99m)Tc(N)-DBODC(5) direct to increase its first-pass extraction keeping unaltered the favorable imaging properties would be desirable. This work describes the synthesis and biological evaluation of a series of novel cationic (99m)Tc-nitrido complexes, of general formula [(99m)TcN(DTC-Ln)(PNP)](+) (DTC-Ln= alicyclic dithiocarbamates; PNP = diphosphinoamine), as potential radiotracers for myocardial perfusion imaging. The synthesis of cationic (99m)Tc-(N)-complexes were accomplished in two steps. Biodistribution studies were performed in rats and compared with the distribution profiles of (99m)Tc(N)-DBODC5 and (99m)Tc-Sestamibi. The metabolisms of the most promising compounds were evaluated by HPLC methods. Biological studies revealed that most of the complexes have a high initial and persistent heart uptake with rapid clearance from nontarget tissues. Among tested compounds, 2 and 12 showed improved heart uptake with respect to the gold standard (99m)Tc-complexes with favorable heart-to-liver and slightly lower heart-to-lung ratios. Chromatographic profiles of (99m)Tc(N)-radioactivity extracted from tissues and fluids were coincident with the native compound evidencing remarkable in vivo stability of these agents. This study shows that the incorporation of alicyclic dithiocarbamate in the [(99m)Tc(N)(PNP)](+) building block yields to a significant increase of the heart uptake at early injection point suggesting that the first-pass extraction fraction of these novel complexes may be increased with respect to the other cationic (99m)Tc-agents keeping almost unaltered the favorable target/nontarget ratios. PMID:20402465

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

    International Nuclear Information System (INIS)

    compsite materials formed by the combination of multivalent metal acid salts and organic polymers provide a new class of (organic-inorganic) hypride ion exchangers with better mechanical and granulometric properties, good ion-exchange capacity, higher chemical and radiation stabilites, reproducibility and selectivity for heavy metals. this material was characterized using X-ray (XRD and XRF), IR, TGA-DTA and total elemental analysis studies. on the basis of distribution studies, the material has been found to be highly selective for pb(II). thermodynamic parameters (i.e δG0, δ S0 and δH0) have also been calculated for the adsorption of Pb2+, Cs+, Fe3+, Cd2+, Cu+2, Zn2+, Co2+ and Eu3+ions on polyacrylamide Sn(IV) molybdophosphate showing that the overall adsorption process is spontaneous endothermic. the mechanism of diffusion of Fe3+, Co2+, Cu+2, Zn2+, Cd2+, Cs+, Pb2+ and Eu3+ in the H-form of polyacrylamide Sn(IV) molybdophosphate composite as cation exchanger was studied as a function of particle size, concentration of the exchanging ions, reaction temperature, dring temperature and pH. the exchange rate was controlled by particle diffusion mechanism as a limited batch techneque and is confirmed from straight lines of B versus 1/r2 polts. the values of diffusion coefficients, activation energy and entropy of activation were calculated and their significance was discussed. the data obtained have been comared with that reported for other organic and inorganic exchangers.

  5. Sequential injection chromatography with post-column reaction/derivatization for the determination of transition metal cations in natural water samples.

    Science.gov (United States)

    Horstkotte, Burkhard; Jarošová, Patrícia; Chocholouš, Petr; Sklenářová, Hana; Solich, Petr

    2015-05-01

    In this work, the applicability of Sequential Injection Chromatography for the determination of transition metals in water is evaluated for the separation of copper(II), zinc(II), and iron(II) cations. Separations were performed using a Dionex IonPAC™ guard column (50mm×2mm i.d., 9 µm). Mobile phase composition and post-column reaction were optimized by modified SIMPLEX method with subsequent study of the concentration of each component. The mobile phase consisted of 2,6-pyridinedicarboxylic acid as analyte-selective compound, sodium sulfate, and formic acid/sodium formate buffer. Post-column addition of 4-(2-pyridylazo)resorcinol was carried out for spectrophotometric detection of the analytes׳ complexes at 530nm. Approaches to achieve higher robustness, baseline stability, and detection sensitivity by on-column stacking of the analytes and initial gradient implementation as well as air-cushion pressure damping for post-column reagent addition were studied. The method allowed the rapid separation of copper(II), zinc(II), and iron(II) within 6.5min including pump refilling and aspiration of sample and 1mmol HNO3 for analyte stacking on the separation column. High sensitivity was achieved applying an injection volume of up to 90µL. A signal repeatability of<2% RSD of peak height was found. Analyte recovery evaluated by spiking of different natural water samples was well suited for routine analysis with sub-micromolar limits of detection.

  6. Role of the metal cation types around VO4 groups on the nonlinear optical behavior of materials: experimental and theoretical analysis.

    Science.gov (United States)

    Su, Xin; Yang, Zhihua; Han, Guopeng; Wang, Ying; Wen, Ming; Pan, Shilie

    2016-09-28

    In order to explore new NLO crystals with superior performances, it is greatly desirable to understand the intrinsic relationship between the macroscopic optical properties and microscopic structural features in crystals. A novel mechanism for nonlinear optical (NLO) effects of vanadate crystals, Li3VO4, KCd4(VO4)3 and Ca3(VO4)2 with distorted (VO4)(3-) groups, has been investigated. Experiments related to the synthesis and structures were determined. In addition, infrared and UV-Vis-NIR diffuse reflectance spectroscopy, as well as electronic band structure calculations, were performed on the reported materials. A comprehensive analysis for the structure-property relationship is given by combining the experimental measurements, the electronic structure calculations and the SHG-weighted electron density to the linear and NLO properties. It was found that the contribution of the (VO4)(3-) anionic group to the second harmonic generation (SHG) response was the dominant anionic group, which plays a vital role to the SHG effects in Li3VO4, KCd4(VO4)3 and Ca3(VO4)2. It was also concluded that the metal cation types and coordination around VO4 groups, the distorted and parallel oriented VO4 tetrahedron decided the SHG coefficient values.

  7. Bivalent transition metal complexes of cetirizine: Spectroscopic, equilibrium studies and biological activity

    Science.gov (United States)

    El-Sherif, Ahmed A.; Shoukry, Mohamed M.; Abobakr, Lamis O.

    2013-08-01

    Metal complexes of cetirizineṡ2HCl (CTZ = 2-[2-[4-[(4-chlorophenyl)phenyl methyl]piperazine-1-yl]-ethoxy]acetic acid, dihydrochloride have been prepared and characterized by elemental analyses, IR, solid reflectance, magnetic moment, molar conductance, and UV-Vis spectra. The analytical data of the complexes show the formation of 1:2 [M:L] ratio, where M represents Ni(II), Co(II) and Cu(II) ions, while L represents the deprotonated CTZ ligand. IR spectra show that CTZ is coordinated to the metal ions in a monodentate manner through carboxylate-O atom. Protonation equilibria of CTZ and its metal complexation by some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaCl) using an automatic potentiometric technique. Thermodynamic parameters for the protonation equilibria of CTZ were calculated and discussed. The stability order of M(II)-CTZ complexes were found to obey Mn2+ pH. The CTZ ligand and its metal complexes were screened for their biological activity against bacterial species (Bacillus subtillis RCMB 010067, Staphylococcus aureus RCMB 010028, Pseudomonas aeuroginosa RCMB 010043, and Escherichia coli RCMB 010052) and fungi as (Aspergillus flavus RCMB 02568, Pencicillium italicum RCMB 03924, Candida albicans RCMB 05031 and Geotricum candidum RCMB 05097). The activity data show that the metal complexes have antibacterial and antifungal activity more than the parent CTZ ligand against one or more bacterial or fungi species. MIC was evaluated for the isolated complexes.

  8. The Metal And Sulphate Removal From Mine Drainage Waters By Biological-Chemical Ways

    Directory of Open Access Journals (Sweden)

    Jenčárová Jana

    2015-06-01

    Full Text Available Mine drainage waters are often characterized by high concentrations of sulphates and metals as a consequence of the mining industry of sulphide minerals. The aims of this work are to prove some biological-chemical processes utilization for the mine drainage water treatment. The studied principles of contamination elimination from these waters include sulphate reduction and metal bioprecipitation by the application of sulphate-reducing bacteria (SRB. Other studied process was metal sorption by prepared biogenic sorbent. Mine drainage waters from Slovak localities Banská Štiavnica and Smolník were used to the pollution removal examination. In Banská Štiavnica water, sulphates decreased below the legislative limit. The elimination of zinc by sorption experiments achieved 84 % and 65 %, respectively.

  9. Transition metal complexes of some biologically active ligands; synthesis characterization and bioactivities

    International Nuclear Information System (INIS)

    Transition/representative transition metals complexes of biologically active chelating agent 1,2-dipyrolodinoethane were synthesized and characterized through spectral and analytical data. The complexes are of the formula (M(L)X/sub 2/). Where (M = Co (II), Ni (II), Cu (II), Zn (II), Hg (II) and Cd (II) and X = CI, Br, NO/sub 3/). Tetrahedral geometry has been proposed to these-metal complexes with the help of magnetic measurements, elemental analysis, chemical stoichiometry and spectroscopic data Antibacterial activity of the ligand and its metal complexes were screened against Eschereschi coli, Klebsiello pneumonia, Proteus mirabilis, Proteus vulhari, Streptococcus pneumonia, Salmonella Iyphi, Bacilh,s anthrax, Streptococcus fecalis and Staphylococcus aureus. Complexes were found to be active against Eschereschi coli, Klebsiella pneumonia, Proteus mirabilis and Proteus vulharis. (author)

  10. The Metals in the Biological Periodic System of the Elements: Concepts and Conjectures.

    Science.gov (United States)

    Maret, Wolfgang

    2016-01-05

    A significant number of chemical elements are either essential for life with known functions, or present in organisms with poorly defined functional outcomes. We do not know all the essential elements with certainty and we know even less about the functions of apparently non-essential elements. In this article, I discuss a basis for a biological periodic system of the elements and that biochemistry should include the elements that are traditionally part of inorganic chemistry and not only those that are in the purview of organic chemistry. A biological periodic system of the elements needs to specify what "essential" means and to which biological species it refers. It represents a snapshot of our present knowledge and is expected to undergo further modifications in the future. An integrated approach of biometal sciences called metallomics is required to understand the interactions of metal ions, the biological functions that their chemical structures acquire in the biological system, and how their usage is fine-tuned in biological species and in populations of species with genetic variations (the variome).

  11. The Metals in the Biological Periodic System of the Elements: Concepts and Conjectures

    Directory of Open Access Journals (Sweden)

    Wolfgang Maret

    2016-01-01

    Full Text Available A significant number of chemical elements are either essential for life with known functions, or present in organisms with poorly defined functional outcomes. We do not know all the essential elements with certainty and we know even less about the functions of apparently non-essential elements. In this article, I discuss a basis for a biological periodic system of the elements and that biochemistry should include the elements that are traditionally part of inorganic chemistry and not only those that are in the purview of organic chemistry. A biological periodic system of the elements needs to specify what “essential” means and to which biological species it refers. It represents a snapshot of our present knowledge and is expected to undergo further modifications in the future. An integrated approach of biometal sciences called metallomics is required to understand the interactions of metal ions, the biological functions that their chemical structures acquire in the biological system, and how their usage is fine-tuned in biological species and in populations of species with genetic variations (the variome.

  12. The Metals in the Biological Periodic System of the Elements: Concepts and Conjectures

    Science.gov (United States)

    Maret, Wolfgang

    2016-01-01

    A significant number of chemical elements are either essential for life with known functions, or present in organisms with poorly defined functional outcomes. We do not know all the essential elements with certainty and we know even less about the functions of apparently non-essential elements. In this article, I discuss a basis for a biological periodic system of the elements and that biochemistry should include the elements that are traditionally part of inorganic chemistry and not only those that are in the purview of organic chemistry. A biological periodic system of the elements needs to specify what “essential” means and to which biological species it refers. It represents a snapshot of our present knowledge and is expected to undergo further modifications in the future. An integrated approach of biometal sciences called metallomics is required to understand the interactions of metal ions, the biological functions that their chemical structures acquire in the biological system, and how their usage is fine-tuned in biological species and in populations of species with genetic variations (the variome). PMID:26742035

  13. Four homochiral coordination polymers contain N-acetyl-L-tyrosine and different N-donor ligand: Influence of metal cations, ancillary ligands and coordination modes

    International Nuclear Information System (INIS)

    Using the chiral ligand N-acetyl-L-tyrosine (Hacty) and maintaining identical reaction conditions, Zn(II), Co(II), and Cd(II) salts provided four novel homochiral coordination polymers ([Zn(acty)(bipy)2(H2O)2]·NO3·2H2O)n1, ([Co(acty)(bipy)2(H2O)2]·NO3·2H2O)n2, ([Cd(acty)2(bipy)H2O]·H2O)n3, and ([Cd(acty)(bpe)2(Ac)]·6H2O)n4 (bipy=4,4′-bipyridine; bpe=1,2-di(4-pyridyl)ethane) in the presence of ancillary ligands. Compounds 1 and 2 are isostructural 1D chain structures. The neighboring chains are further linked into a 3D supramolecular structure via π⋯π stacking and hydrogen bond interactions. Compound 3 shows a 2D network and 4 generates 1D infinite chains along the c-axis. Compounds 3 and 4 are further connected into 3D supramolecular network by hydrogen bond interactions. More importantly, coordination in acyl oxygen atoms and ancillary ligands (bpe) as monodentate decorating ligands in 4 are rarely reported. Ancillary ligands and metal cations significantly influence the structure of the complexes. The photoluminescence properties of 1, 3, and 4 were studied at room temperature. Circular dichroism (CD) of the complexes have been investigated. - Graphical abstract: Four new homochiral coordination polymers were prepared and structurally characterized, which investigate the influence of the ancillary ligands and metal ions on the design and synthesis of coordination polymers. Display Omitted - Highlights: • It is rarely reported that the chiral coordination polymers prepared with N-acetyl-L-tyrosine ligands. • The alkalescent acetyl oxygen atom is difficult to participate in coordination but it is happened in the N-acetyl-L-tyrosine ligands. • The ancillary ligands (4,4′-bipy and bpe) are present in an unusual coordination modes, monodentate decorating ligands in 1, 2 and 4. • Structure comparative analyses results indicate that the secondary ligands and metal ions influence the fabrication of these inorganic–organic arrangements

  14. Metal Complexes of Macrocyclic Schiff-Base Ligand: Preparation, Characterisation, and Biological Activity

    Science.gov (United States)

    Ahmed, Riyadh M.; Yousif, Enaam I.; Hasan, Hasan A.; Al-Jeboori, Mohamad J.

    2013-01-01

    A new macrocyclic multidentate Schiff-base ligand Na4L consisting of two submacrocyclic units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12]tetracosa-1(23),2,6,8,10,12(24),13,17,19,21,-decaene-23,24-disodium) and its tetranuclear metal complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) are reported. Na4L was prepared via a template approach, which is based on the condensation reaction of sodium 2,4,6-triformyl phenolate with ethylenediamine in mole ratios of 2 : 3. The tetranuclear macrocyclic-based complexes were prepared from the reaction of the corresponding metal chloride with the ligand. The mode of bonding and overall geometry of the compounds were determined through physicochemical and spectroscopic methods. These studies revealed tetrahedral geometries about Mn, Co, and Zn atoms. However, square planar geometries have been suggested for NiII and CuII complexes. Biological activity of the ligand and its metal complexes against Gram positive bacterial strain Staphylococcus aureus and Gram negative bacteria Escherichia coli revealed that the metal complexes become more potentially resistive to the microbial activities as compared to the free ligand. However, these metal complexes do not exhibit any effects on the activity of Pseudomonas aeruginosa bacteria. There is therefore no inhibition zone. PMID:23935414

  15. Chelating impact assessment of biological ad chemical chelates on metal extraction from contaminated soils

    International Nuclear Information System (INIS)

    Soil contamination is the result of uncontrolled waste dumping and poor practices by humans. Of all the pollutants heavy metals are of particular concern due to their atmospheric deposition, leaching capacity and non-biodegradability. Heavy metal containing effluent is discharged into the agricultural fields and water bodies. This results in the accumulation of heavy metals in soil and the crops grown on that soil. Studies have revealed detrimental impacts on soil fertility and the poor health of animals and humans. Phytoextraction is widely researched for remediation of heavy metal contaminated soil. To enhance the effect of phytoextraction heavy metals have to be available to the plants in soluble form. In this study the potential of different chelating agents was assessed in solubilizing the heavy metals making easy for plants to uptake them. For this purpose efficient chemical and biological chelating agent had to be identified. Along with that an optimum dose and application time for chemical chelating agent was determined. Ethylenediamine tetraacetic acid (EDTA), Diethylene triamine pentaacetic acid (DTPA), Nitriloacetic acid (NTA) were applied to the soil, containing Pb, Cr, Cu and Cd, at different concentrations and application time. Aspergillus niger and Aspergillus flavus were incubated in soil for different time periods. In correspondence with findings of the study, Pb and Cr were best solubilized by 5mM EDTA. For Cd and Cu 5mM DTPA carried out efficient chelation. NTA showed relatively inadequate solubilisation, although for Cr it performed equal to EDTA. A. niger and A. flavus instead of solubilizing adsorbed the metals in their biomass. Adsorption was mainly carried out by A. niger. (author)

  16. Fragmentation study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, using post-source decay matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Kéki, S; Deák, G; Zsuga, M

    2001-12-01

    A post-source decay matrix-assisted laser desorption/ionization mass spectrometric (PSD-MALDI-MS) study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, is reported. The fragmentations of rutin were performed by selecting the [R + Cat]+ peaks for PSD, where R represents a rutin molecule and Cat an alkali metal ion (Li+, Na+, K+). The PSD-MALDI mass spectra showed, depending on Cat, different fragmentation patterns with respect to both the quality and quantity of the fragment ions formed. The intensity of fragmentation decreased in the order Li+ > Na+ > K+. The fragmentation mechanism and an explanation for the observed differences are suggested.

  17. Detection of heavy-metal ions using liquid crystal droplet patterns modulated by interaction between negatively charged carboxylate and heavy-metal cations.

    Science.gov (United States)

    Han, Gyeo-Re; Jang, Chang-Hyun

    2014-10-01

    Herein, we demonstrated a simple, sensitive, and rapid label-free detection method for heavy-metal (HM) ions using liquid crystal (LC) droplet patterns on a solid surface. Stearic-acid-doped LC droplet patterns were spontaneously generated on an n-octyltrichlorosilane (OTS)-treated glass substrate by evaporating a solution of the nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), dissolved in heptane. The optical appearance of the droplet patterns was a dark crossed texture when in contact with air, which represents the homeotropic orientation of the LC. This was caused by the steric interaction between the LC molecules and the alkyl chains of the OTS-treated surface. The dark crossed appearance of the acid-doped LC patterns was maintained after the addition of phosphate buffered saline (PBS) solution (pH 8.1 at 25°C). The deprotonated stearic-acid molecules self-assembled through the LC/aqueous interface, thereby supporting the homeotropic anchoring of 5CB. However, the optical image of the acid-doped LC droplet patterns incubated with PBS containing HM ions appeared bright, indicating a planar orientation of 5CB at the aqueous/LC droplet interface. This dark to bright transition of the LC patterns was caused by HM ions attached to the deprotonated carboxylate moiety, followed by the sequential interruption of the self-assembly of the stearic acid at the LC/aqueous interface. The results showed that the acid-doped LC pattern system not only enabled the highly sensitive detection of HM ions at a sub-nanomolar concentration but it also facilitated rapid detection (<10 min) with simple procedures.

  18. Detection of heavy-metal ions using liquid crystal droplet patterns modulated by interaction between negatively charged carboxylate and heavy-metal cations.

    Science.gov (United States)

    Han, Gyeo-Re; Jang, Chang-Hyun

    2014-10-01

    Herein, we demonstrated a simple, sensitive, and rapid label-free detection method for heavy-metal (HM) ions using liquid crystal (LC) droplet patterns on a solid surface. Stearic-acid-doped LC droplet patterns were spontaneously generated on an n-octyltrichlorosilane (OTS)-treated glass substrate by evaporating a solution of the nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), dissolved in heptane. The optical appearance of the droplet patterns was a dark crossed texture when in contact with air, which represents the homeotropic orientation of the LC. This was caused by the steric interaction between the LC molecules and the alkyl chains of the OTS-treated surface. The dark crossed appearance of the acid-doped LC patterns was maintained after the addition of phosphate buffered saline (PBS) solution (pH 8.1 at 25°C). The deprotonated stearic-acid molecules self-assembled through the LC/aqueous interface, thereby supporting the homeotropic anchoring of 5CB. However, the optical image of the acid-doped LC droplet patterns incubated with PBS containing HM ions appeared bright, indicating a planar orientation of 5CB at the aqueous/LC droplet interface. This dark to bright transition of the LC patterns was caused by HM ions attached to the deprotonated carboxylate moiety, followed by the sequential interruption of the self-assembly of the stearic acid at the LC/aqueous interface. The results showed that the acid-doped LC pattern system not only enabled the highly sensitive detection of HM ions at a sub-nanomolar concentration but it also facilitated rapid detection (<10 min) with simple procedures. PMID:25059128

  19. Synthesis, Characterization and Biological Evaluation of Transition Metal Complexes Derived from N, S Bidentate Ligands

    Directory of Open Access Journals (Sweden)

    Enis Nadia Md Yusof

    2015-05-01

    Full Text Available Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC with 2-methoxybenzaldehyde (2MB and 3-methoxybenzaldehyde (3MB. The ligands were reacted separately with acetates of Cu(II, Ni(II and Zn(II yielding 1:2 (metal:ligand complexes. The metal complexes formed were expected to have a general formula of [M(NS2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1 and S2M3MBH (2 were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7 and estrogen receptor-negative (MDA-MB-231 breast cancer cell lines. Only the Cu(II complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II complexes have a strong DNA binding affinity.

  20. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases

    Science.gov (United States)

    Hanif, Muhammad; Chohan, Zahid H.

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L1-L3 have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

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

    Science.gov (United States)

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

    2013-03-01

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

  2. Schwertmannite and Fe oxides formed by biological low-pH Fe(II) oxidation versus abiotic neutralization: Impact on trace metal sequestration

    Science.gov (United States)

    Burgos, William D.; Borch, Thomas; Troyer, Lyndsay D.; Luan, Fubo; Larson, Lance N.; Brown, Juliana F.; Lambson, Janna; Shimizu, Masayuki

    2012-01-01

    Three low-pH coal mine drainage (CMD) sites in central Pennsylvania were studied to determine similarities in sediment composition, mineralogy, and morphology. Water from one site was used in discontinuous titration/neutralization experiments to produce Fe(III) minerals by abiotic oxidative hydrolysis for comparison with the field precipitates that were produced by biological low-pH Fe(II) oxidation. Even though the hydrology and concentration of dissolved metals of the CMD varied considerably between the three field sites, the mineralogy of the three iron mounds was very similar. Schwertmannite was the predominant mineral precipitated at low-pH (2.5-4.0) along with lesser amounts of goethite. Trace metals such as Zn, Ni and Co were only detected at μmol/g concentrations in the field sediments, and no metals (other than Fe) were removed from the CMD at any of the field sites. Metal cations were not lost from solution in the field because of unfavorable electrostatic attraction to the iron mound minerals. Ferrihydrite was the predominant mineral formed by abiotic neutralization (pH 4.4-8.4, 4 d aging) with lesser amounts of schwertmannite and goethite. In contrast to low-pH precipitation, substantial metal removal occurred in the neutralized CMD. Al was likely removed as hydrobasaluminite and Al(OH) 3, and as a co-precipitate into schwertmannite or ferrihydrite. Zn, Ni and Co were likely removed via adsorption onto and co-precipitation into the freshly formed Fe and Al solids. Mn was likely removed by co-precipitation and, at the highest final pH values, as a Mn oxide. Biological low-pH Fe(II) oxidation can be cost-effectively used to pre-treat CMD and remove Fe and acidity prior to conventional neutralization techniques. A further benefit is that solids formed under these conditions may be of industrial value because they do not contain trace metal or metalloid contaminants.

  3. Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology

    Energy Technology Data Exchange (ETDEWEB)

    Lentz, Nicholas B. [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was found that instrument interface design also plays a critical role in the cluster ion distribution seen in the mass spectrum. In Chapter 5, ESI-MS was used to investigate toxic metal binding to the [Gln11]-amyloid β-protein fragment (1-16). Pb and Cd bound stronger than Zn, even in the presence of excess Zn. Hg bound weaker than Zn. There are endless options for future work on cluster ions. Any molecule that is poorly ionized in positive ion mode can potentially show an increase in ionization efficiency if an appropriate anion is used to produce a net negative charge. It is possible that drug protein or drug/DNA complexes can also be stabilized by adding counter-ions. This would preserve the solution characteristics of the complex in the gas phase. Once in the gas phase, CID could determine the drug binding location on the biomolecule. There are many research projects regarding toxic metals in biology that have yet to be investigated or even discovered. This is an area of research with an almost endless future because of the changing dynamics of biological systems. What is deemed safe today may show toxic effects in the future. Evolutionary changes in protein structures may render them more susceptible to toxic metal binding. As the understanding of toxicity evolves, so does the demand for new toxic metal research. New instrumentation designs and software make it possible to perform research that could not be done in the past. What was undetectable yesterday will

  4. [Bioaccumulation and Biomagnification of Heavy Metals in Three Gorges Reservoir and Effect of Biological Factors].

    Science.gov (United States)

    Wei, Li-li; Zhou, Qiong; Xie, Cong-xin; Wang, Jun; Li, Jun

    2016-01-15

    Three Gorges Reservoir (TGR) reached the maximum water level (175 m) of impoundment in Oct. 2010. In order to reveal the potential influence of the greatest water-level impoundment on the heavy metal pollution in the typical waters of TGR, the content level of trace metals ( Hg, Cd and Pb) in biota and potential biomagnification along the aquatic food chain were investigated in the main stem of TGR from July 2011 to August 2012, as well as the relationship between the trace metal concentrations of aquatic consumers (fish and aquatic invertebrate) and biological factors. Our study showed that no individual data of the three trace metals in biota exceeded the edible safety criteria of aquatic products in China and FAO. In contrast with those before the impoundment of TGR, Hg showed a little higher, while Cd and Pb exhibited a little lower level after the impoundment. Trace metals in TGR exhibited relatively lower concentrations compared with those in reservoirs in other countries. Significant correlations were found between the Cd concentration and body size (body length and body weight) of Cyprinus carpio, as well as the Hg concentration and body size (body length and body weight) of Erythroculter ilishaeformis. As for feeding habits, there was statistically significant difference between trace metal concentrations in herbivorous, planktonic, omnivorous and carnivorous fish. However, no significant difference was found between the metal concentrations in fish with different habitats (pelagic, mesopelagic and benthic). Even so, the overall trend was that fish living in benthic layer had higher heavy metal concentrations than those in pelagic and mesopelagic zones. The regression slopes of log-Hg concentration versus delta(15)N, served as an indicator of trophic magnification factor (TMF). Significant correlations (P < 0.05) were observed for Hg in the food web of TGR. TMF of Hg in TGR indicated lower level (0.046-0.066) in contrast with those in the reservoirs of

  5. Spectroscopic Properties of Novel Aromatic Metal Clusters: NaM4 (M=Al, Ga, In) and their Cations and Anions

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, K; Zhao, C

    2004-03-17

    The ground and several excited states of metal aromatic clusters, namely NaM4 and NaM{sub 4}{sup {+-}} (M=Al, Ga, In) clusters have been investigated by employing complete activespace self-consistent-field (CASSCF) followed by Multi-reference singles and doubles configuration interaction (MRSDCI) computations that included up to 10 million configurations and other methods. The ground states NaM{sub 4}{sup -} of aromatic anions are found to be symmetric C{sub 4v} ({sup 1}A{sub 1}) electronic states with ideal square pyramid geometries. While the ground state of NaIn4 is also predicted to be a symmetric C{sub 4v} ({sup 2}A{sub 1}) square pyramid, the ground state of the NaAl4 cluster is found to have a C{sub 2v} ({sup 2}A{sub 1}) pyramid with a rhombus base and the ground state of NaGa{sub 4} possesses a C{sub 2v} ({sup 2}A{sub 1}) pyramid with a rectangle base. In general these structures exhibit 2 competing geometries, viz., an ideal C{sub 4v} structure and a distorted rhomboidal or rectangular pyramid structure (C{sub 2v}). All of the ground states of the NaM{sub 4}{sup +} (M= Al, Ga, In) cations are computed to be C{sub 2v} ({sup 3}A{sub 2}) pyramids with rhombus bases. The equilibrium geometries, vibrational frequencies, dissociation energies, adiabatic ionization potentials, adiabatic electron affinities for the electronic states of NaM{sub 4} (M=Al, Ga, In) and their ions are computed and compared with experimental results and other theoretical calculations. On the basis of our computed excited states energy separations, we have tentatively suggested assignments to the observed X and A states in the anion photoelectron spectra of Al{sub 4}Na{sup -} reported by Li et al. The X state can be assigned to a C{sub 2v} ({sup 2}A{sub 1}) rhomboidal pyramid. The A state observed in the anion spectrum is assigned to the first excited state ({sup 2}B{sub 1}) of the neutral NaAl{sub 4} with the C{sub 4v} symmetry. The assignments of the excited states are consistent with

  6. Synthesis, characterization and biological evaluation of Rutin-zinc(II) flavonoid -metal complex.

    Science.gov (United States)

    Ikeda, Norma Estefania Andrades; Novak, Estela Maria; Maria, Durvanei Augusto; Velosa, Adélia Segin; Pereira, Regina Mara Silva

    2015-09-01

    Synthesis of compounds analogous to natural products from secondary metabolites, such as flavonoids, is a promising source of novel drugs. Rutin (quercetin-3-O-rutinoside) is a natural flavone, which has, in its chemical structure, different sites for coordination with transition metals and the complexation with these metals enhances its biological properties. Rutin-zinc(II), a flavonoid-metal complex, was synthesized and characterized by UV-VIS, FT-IR, elemental analysis and (1)H NMR. The antioxidant and antitumor activities, as well as the cytotoxicity and in vivo toxicity of this complex were evaluated and compared with the free rutin. Rutin-zinc(II) has not shown any cytotoxicity against normal cells (fibroblasts and HUVECs) or toxicity in BALB/c mice, but has shown antioxidant activity in vitro and cytotoxicity against leukemia (KG1, K562 and Jurkat), multiple myeloma (RPMI8226) and melanoma (B16F10 and SK-Mel-28) cell lines in vitro. In Ehrlich ascites carcinoma model, Rutin-zinc(II) modulated the mitochondrial membrane potential and the expression of genes related to cell cycle progression, angiogenesis and apoptosis.

  7. Determination of polycyclic aromatic compounds and heavy metals in sludges from biological sewage treatment plants.

    Science.gov (United States)

    Bodzek, D; Janoszka, B; Dobosz, C; Warzecha, L; Bodzek, M

    1997-07-11

    The procedure of the analysis of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in the sludges from biological sewage treatment plants has been worked out. The analysis included isolation of organic matter from sludges, separation of the extract into fractions of similar chemical character, qualitative-quantitative analysis of individual PAHs and their nitrogenated and oxygenated derivatives. Liquid-solid chromatography, solid-phase extraction and semipreparative band thin-layer chromatography techniques were used for the separation. Capillary gas chromatography-mass spectrometry analysis of the separated fractions enabled identification of more than 21 PAHs, including hydrocarbons which contained 2-6 aromatic rings as well as their alkyl derivatives, 10 oxygen derivatives, 9 nitroarenes, aminoarenes and over 20 azaarenes and carbazoles. Using the capillary gas chromatography-flame ionization detection technique the content of 17 dominant PAHs was determined. The content of heavy metals was determined in investigated sludges with the use of atomic absorption spectrometry. The concentrations of the respective metals could be ranked in the order Cd coal mine wastes, taking into consideration the contents of toxic organic pollutants and heavy metals. PMID:9253190

  8. Chemical and biological properties of toxic metals and use of chelating agents for the pharmacological treatment of metal poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Sinicropi, Maria Stefania; Caruso, Anna [University of Calabria, Department of Pharmaceutical Sciences, Rende (Italy); Amantea, Diana [University of Calabria, Department of Pharmacobiology, Rende (Italy); Saturnino, Carmela [University of Salerno, Department of Pharmaceutical Sciences, Fisciano (Italy)

    2010-07-15

    Exposure to toxic metals is a well-known problem in industrialized countries. Metals interfere with a number of physiological processes, including central nervous system (CNS), haematopoietic, hepatic and renal functions. In the evaluation of the toxicity of a particular metal it is crucial to consider many parameters: chemical forms (elemental, organic or inorganic), binding capability, presence of specific proteins that selectively bind metals, etc. Medical treatment of acute and chronic metal toxicity is provided by chelating agents, namely organic compounds capable of interacting with metal ions to form structures called chelates. The present review attempts to provide updated information about the mechanisms, the cellular targets and the effects of toxic metals. (orig.)

  9. Role of Metal Cations on the corrosion behaviour of 8090-T851 in a pH 2.0 solution

    DEFF Research Database (Denmark)

    Murthy, K.S.N.; Ambat, Rajan; Dwarakadasa, E.S.

    1994-01-01

    The influence of cations such as Cu2+, Al3+ and Li+ on the corrosion behaviour of 8090-T851(Al-Li) alloy in a pH 2.0 HCl solution was investigated by weight loss and polarisation techniques. Weight loss experiments showed that the effect of cation is a strong function of its nature and concentrat...... indicated that the corrosion activation by Al3+ ions is due to their chemical reactivity with the corroding substrate. Little enhancement in corrosion by Li+ ions is attributed to the increase in solution conductivity in their presence....

  10. A multimodal imaging workflow to visualize metal mixtures in the human placenta and explore colocalization with biological response markers.

    Science.gov (United States)

    Niedzwiecki, Megan M; Austin, Christine; Remark, Romain; Merad, Miriam; Gnjatic, Sacha; Estrada-Gutierrez, Guadalupe; Espejel-Nuñez, Aurora; Borboa-Olivares, Hector; Guzman-Huerta, Mario; Wright, Rosalind J; Wright, Robert O; Arora, Manish

    2016-04-01

    Fetal exposure to essential and toxic metals can influence life-long health trajectories. The placenta regulates chemical transmission from maternal circulation to the fetus and itself exhibits a complex response to environmental stressors. The placenta can thus be a useful matrix to monitor metal exposures and stress responses in utero, but strategies to explore the biologic effects of metal mixtures in this organ are not well-developed. In this proof-of-concept study, we used laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to measure the distributions of multiple metals in placental tissue from a low-birth-weight pregnancy, and we developed an approach to identify the components of metal mixtures that colocalized with biological response markers. Our novel workflow, which includes custom-developed software tools and algorithms for spatial outlier identification and background subtraction in multidimensional elemental image stacks, enables rapid image processing and seamless integration of data from elemental imaging and immunohistochemistry. Using quantitative spatial statistics, we identified distinct patterns of metal accumulation at sites of inflammation. Broadly, our multiplexed approach can be used to explore the mechanisms mediating complex metal exposures and biologic responses within placentae and other tissue types. Our LA-ICP-MS image processing workflow can be accessed through our interactive R Shiny application 'shinyImaging', which is available at or through our laboratory's website, . PMID:26987553

  11. Investigation of the soluble metals in tissue as biological response pattern to environmental pollutants (Gammarus fossarum example).

    Science.gov (United States)

    Filipović Marijić, Vlatka; Dragun, Zrinka; Sertić Perić, Mirela; Matoničkin Kepčija, Renata; Gulin, Vesna; Velki, Mirna; Ečimović, Sandra; Hackenberger, Branimir K; Erk, Marijana

    2016-07-01

    In the present study, Gammarus fossarum was used to investigate the bioaccumulation and toxic effects of aquatic pollutants in the real environmental conditions. The novelty of the study is the evaluation of soluble tissue metal concentrations in gammarids as indicators in early assessment of metal exposure. In the Sutla River, industrially/rurally/agriculturally influenced catchment in North-Western Croatia, physico-chemical water properties pointed to disturbed ecological status, which was reflected on population scale as more than 50 times lower gammarid density compared to the reference location, Črnomerec Stream. Significantly higher levels of soluble toxic metals (Al, As, Cd, Pb, Sb, Sn, Sr) were observed in gammarids from the Sutla River compared to the reference site and reflected the data on higher total dissolved metal levels in the river water at that site. The soluble metal estimates were supplemented with the common multibiomarker approach, which showed significant biological responses for decreased acetylcholinesterase activity and increased total soluble protein concentrations, confirming stressed environmental conditions for biota in the Sutla River. Biomarker of metal exposure, metallothionein, was not induced and therefore, toxic effect of metals was not confirmed on molecular level. Comparable between-site pattern of soluble toxic metals in gammarids and total dissolved metal levels in water suggests that prior to biomarker response and observed toxic impact, soluble metals in tissue might be used as early warning signs of metal impact in the aquatic environment and improve the assessment of water quality. PMID:27060638

  12. Comparative Study of the Effects of Long and Short Term Biological Processes on the Cycling of Colloidal Trace Metals

    Science.gov (United States)

    Pinedo, P.; Sanudo-Wilhelmy, S. A.; West, A.

    2013-05-01

    Nanoparticle (or colloids), with sizes operationally defined as ranging from 1nm to 1000nm diameter, are thought to play an important role in metal cycling in the ocean due to their high surface area to volume ratio and abundance in marine systems. In coastal waters, the bulk of marine nanoparticles are organic, so short and long term biological processes are expected to influence the dynamics of these types of particles in marine environments. This is, in turn, expected to influence metal concentrations. Here we selected two different environments to study the influence of long-term biological events (phytoplankton blooms) and short-term biological events (diel cycles of photosynthesis and respiration) on the cycling of colloidal trace metals. We focus on Cu and Fe, both biogeochemically important metals but with differing colloidal behavior. Long term processes (West Neck Bay): A bay (West Neck Bay, Long Island) with predictable natural phytoplankton blooms, but with limited inputs of freshwater, nutrients and metals, was selected to study the partitioning of Cu and Fe between colloidal and soluble pools over the course of a bloom. During the bloom, there was a significant build-up of Cu associated with DOM accumulation and a removal of Fe via particle stripping. Fraction-specific metal concentrations, and metal accumulation and removal rates, were found to be significantly correlated with chlorophyll-a concentration and with dissolved organic matter (DOM). Short term processes (Catalina Island): To identify the cyclical variation in metal speciation during diel (24-hour) cycles of photosynthesis and respiration, we conducted a study off Catalina Island, a pristine environment where trace metal cycling is solely controlled by biological processes and changes in the phytoplankton community are well characterized. The speciation of Fe between soluble and colloidal pools showed that Fe has a high affinity for colloidal material and that the distribution between

  13. Application of Glow Discharge Aes for Investigation of Metal Ions and Water in Biology and Medicine

    CERN Document Server

    Bregadze, Vasil G; Tsakadze, Ketevan J

    2007-01-01

    AES VHF inductively coupled plasmatron may be applied to wide range of studies. It enables rapid microanalysis of various solutions including biological objects and peripheral blood serum. In addition, it may be used for investigation of water desorption from solid bodies and for determination of energetic metal-macromolecule complexes. Study of hydration energy and hydration number by kinetic curves of water glow discharge atomic spectral analysis of hydrogen (GD EAS analysis of hydrogen) desorption from Na-DNA humidified fibers allowed to reveal that structural and conformational changes in activation energy of hydrated water molecules increases by 0.65kcal/Mole of water. The developed method of analysis of elements in solutions containing high concentrations of organic materials allows systematic study of practically healthy persons and reveals risk factors for several diseases. Microelemental content of blood serum fractions showed that amount of not bounded with ceruloplasmin copper was three times more ...

  14. Mapping the Metal Uptake in Plants from Jasper Ridge Biological Preserve - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Allison [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-24

    Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentinetolerant plants. Rye grown on potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.

  15. Designing, syntheses, characterization, computational study and biological activities of silver-phenothiazine metal complex

    Science.gov (United States)

    Kumar, Vijay; Upadhyay, Niraj; Manhas, Anu

    2015-11-01

    A noble biologically active compound Ag(I)-PTZ metal complex (1) with spherical morphology was synthesized first time. Entire characterization tool (spectral, elemental, mass and thermal analysis) was supported a distorted tetrahedral structure, where two water compounds were coordinated with Ag(I) including one phenothiazine and one nitrate group. For the better insight, obtained spectral/structural results were supported by 3D molecular modeling. Compound 1 had shown excellent activities against the Salmonella typhimurium and Aspergillus fumigatus with minimum inhibitory concentration (MIC) value 20 mg/L and 25 mg/L. The observed antioxidant radical scavenging activity (in %) of compound 1 (62.74%) was more than control ascorbic acid (28.58%). The observed protein (BSA) binding constant of 1 was 8.86 × 104 M-1, which is similar to binding constant of salicylic acid with BSA protein. Initial studies have revealed that synthesized compound 1 may act as multipurpose drug analogue in future.

  16. Synthesis, Spectroscopic Characterization and Biological Activities of Transition Metal Complexes Derived from a Tridentate Schiff Base

    Directory of Open Access Journals (Sweden)

    J. Senthil Kumaran

    2013-01-01

    Full Text Available A new series of Cu (II, Ni (II, Co (II and Zn (II complexes have been synthesized from the Schiff base derived from 4-hydroxy-3-methoxybenzylidine-4-aminoantipyrine and 2-aminophenol. The structural features have been determined from their elemental analysis, magnetic susceptibility, molar conductance, Mass, IR, UV-Vis, 1H-NMR, 13C-NMR and ESR spectral studies. The redox behavior of the copper complex has been studied by cyclic voltammetry. The data confirm that the complexes have composition of ML2 type. The electronic absorption spectral data of the complexes propose an octahedral geometry around the central metal ion. All the metal complexes with DNA structure were guided by the presence of inter-molecular C–H⋯O and C–H⋯N hydrogen bonds. The biological activity of the synthesized compounds were tested against the bacterial species such as Bacillus subtilis, Staphylococcus aureus, Proteus vulgaris and fungal species such as Candida albicans by the well-diffusion method.

  17. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates

    Science.gov (United States)

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

  18. Exposure assessment to heavy metals in general population in a polluted area through biological monitoring

    Directory of Open Access Journals (Sweden)

    Vimercati L.

    2013-04-01

    Full Text Available In polluted areas, a major issue is the correct assessment of the exposure of general population to industrial pollutants. The objectives were: to evaluate the exposure to heavy metals emitted from the industrial area of Taranto; to correlate biological monitoring data with environmental data, in order to clarify the impact of industrial pollution in terms of internal dose. A cross sectional study has been designed to measure levels of urinary arsenic, lead, cadmium, chromium, manganese in 300 inhabitants of Taranto, Statte and Laterza. Adult subjects have been selected by a two-stage random stratified sampling. Results are based on 272 subjects (131 men and 141 women. The observed concentrations of metals in the whole study population are overall high. The median values for lead (7.4 μg/l and chromium (0.4 μg/l are higher than the 95° percentile of the range of reference values. For manganese and arsenic the 95° percentile of concentration in the whole study population is higher than the 95° percentile of the range of reference values. Concentrations of mercury in the whole study population are comparable to reference.

  19. Surface-enhanced and tip-enhanced Raman spectroscopy of biological molecules on nanostructured metallic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hennemann, Laura E.; Mihaljevic, Josip; Braun, Kai; Meixner, Alfred J.; Zhang, Dai [Institute of Physical and Theoretical Chemistry, University of Tuebingen, Tuebingen (Germany); Kolloch, Andreas [Department of Physics, University of Konstanz, Universitaetsstrasse 10, 78457 Konstanz (Germany)

    2011-07-01

    We use a custom built apertureless scanning near-field optical microscope (SNOM) to investigate several kinds of biological molecules. The setup is an extended parabolic mirror based confocal microscope working with higher order laser modes in order to tune the polarization of the light in its focus. We detected the presence of a (sub)monolayer of biological molecules ranging from DNA bases to double stranded DNA by collecting their unique Raman fingerprint spectrum. In order to detect such small amounts of molecules, we performed surface-enhanced Raman scattering (SERS) or tip-enhanced Raman scattering (TERS). For SERS, either the irregular rough edges of evaporated noble metal grids or regular arrays of gold nano triangles served as enhancing substrates. We compared the plasmonic properties of gold triangles of different aspect ratios and on different substrates to optimize the electromagnetic enhancement for the 632.8 nm laser excitation. The obtained optical patterns were compared to those computed in simulations. In the case of TERS, an electrochemically etched sharp gold tip (approx. 20 nm tip apex diameter) was approached to the surface, thus acting simultaneously as a scanning probe microscopy tip for topographic measurements and as a near-field antenna collecting optical information. We collected TERS spectra of single calf thymus DNA molecules immobilized on smooth Au(111) surfaces. Strongly enhanced spectra were obtained both in the SERS and in the TERS measurements.

  20. Solid State Structures of Alkali Metal Ion Complexes Formed by Low-Molecular-Weight Ligands of Biological Relevance.

    Science.gov (United States)

    Aoki, Katsuyuki; Murayama, Kazutaka; Hu, Ning-Hai

    2016-01-01

    This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of alkali metal ion complexes containing low-molecular-weight ligands of biological relevance, mostly obtained from the Cambridge Structural Database (the CSD version 5.35 updated to February 2014). These ligands include (i) amino acids and small peptides, (ii) nucleic acid constituents (excluding quadruplexes and other oligonucleotides), (iii) simple carbohydrates, and (iv) naturally occurring antibiotic ionophores. For some representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described. PMID:26860299

  1. Photocatalytic Reactive Oxygen Species Formation by Semiconductor-Metal Hybrid Nanoparticles. Toward Light-Induced Modulation of Biological Processes.

    Science.gov (United States)

    Waiskopf, Nir; Ben-Shahar, Yuval; Galchenko, Michael; Carmel, Inbal; Moshitzky, Gilli; Soreq, Hermona; Banin, Uri

    2016-07-13

    Semiconductor-metal hybrid nanoparticles manifest efficient light-induced spatial charge separation at the semiconductor-metal interface, as demonstrated by their use for hydrogen generation via water splitting. Here, we pioneer a study of their functionality as efficient photocatalysts for the formation of reactive oxygen species. We observed enhanced photocatalytic activity forming hydrogen peroxide, superoxide, and hydroxyl radicals upon light excitation, which was significantly larger than that of the semiconductor nanocrystals, attributed to the charge separation and the catalytic function of the metal tip. We used this photocatalytic functionality for modulating the enzymatic activity of horseradish peroxidase as a model system, demonstrating the potential use of hybrid nanoparticles as active agents for controlling biological processes through illumination. The capability to produce reactive oxygen species by illumination on-demand enhances the available peroxidase-based tools for research and opens the path for studying biological processes at high spatiotemporal resolution, laying the foundation for developing novel therapeutic approaches. PMID:27224678

  2. Influence of biologically-active substances on 137Cs and heavy metals uptake by Barley plant

    International Nuclear Information System (INIS)

    Available in abstract form only. Full text of publication follows: When solving the problem of contaminated agricultural lands rehabilitation, most of attention is concentrated on the effective means which allow the obtaining of ecologically safe production. The minimization of radionuclides and heavy metals (HM) content in farm products on the basis of their migration characteristics in agro-landscapes and with the regard for different factors influencing contaminants behavior in the soil-plant system is of great significance. Our investigation has shown that the effect of biologically active substances (BAS) using for seeds treatment on 137Cs transfer to barley grown on Cd contaminated soil was dependent on their properties and dosage, characteristics of soil contamination and biological peculiarities of plants, including stage of plants development. Seeds treatment by plant growth regulator Zircon resulted in a significant increase in 137Cs activity in harvest (40- 50%), increase in K concentration and significant reduction in Ca concentration. Increased Cd content in soil reduced 137Cs transfer to barley plants by 30-60% (p137Cs uptake by roots and Cd and Pb phyto-toxicity. The experimental data do not make it possible to link the BAS effect on inhibition of 137Cs absorption by plants directly with their influence on HM phyto-toxicity. The dependence of Concentration Ratio of 137Cs on the Ambiol and El dose was not proportional and the most significant decrease in the radionuclide uptake by plants was reported with the use of dose showing the most pronounced stimulating effect on the barley growth and development. The pre-sowing seed treatment with Ambiol increased Pb absorption by 35-50% and, on the contrary, decreased Cd uptake by plants by 30-40%. (authors)

  3. A Study of Different Doped Metal Cations on the Physicochemical Properties and Catalytic Activities of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) Composite Oxides for Nitric Oxide Reduction by Carbon Monoxide.

    Science.gov (United States)

    Deng, Changshun; Li, Min; Qian, Junning; Hu, Qun; Huang, Meina; Lin, Qingjin; Ruan, Yongshun; Dong, Lihui; Li, Bin; Fan, Minguang

    2016-08-01

    This work is mainly focused on investigating the effects of different doped metal cations on the formation of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) composite oxides and their physicochemical and catalytic properties for NO reduction by CO as a model reaction. The obtained samples were characterized by using N2 physisorption, X-ray diffraction, laser Raman spectroscopy, UV/Vis diffuse reflectance spectroscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by hydrogen and by oxygen (H2 -TPR and O2 -TPD), in situ diffuse reflectance infrared Fourier transform spectroscopy, and the NO+CO model reaction. The results imply that the introduction of M(x+) into the lattice of CeO2 increases the specific surface area and pore volume, especially for variable valence metal cations, and enhances the catalytic performance to a great extent. In this regard, increases in the oxygen vacancies, reduction properties, and chemisorbed O2 (-) (and/or O(-) ) species of these Ce20 M1 Ox composite oxides (M refers to variable valence metals) play significant roles in this reaction. Among the samples, Ce20 Cr1 Ox exhibited the best catalytic performance, mainly because it has the best reducibility and more chemisorbed oxygen, and significant reasons for these attributes may be closely related to favorable synergistic interactions of the vacancies and near-surface Ce(3+) and Cr(3+) . Finally, a possible reaction mechanism was tentatively proposed to understand the reactions. PMID:27435470

  4. A Study of Different Doped Metal Cations on the Physicochemical Properties and Catalytic Activities of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) Composite Oxides for Nitric Oxide Reduction by Carbon Monoxide.

    Science.gov (United States)

    Deng, Changshun; Li, Min; Qian, Junning; Hu, Qun; Huang, Meina; Lin, Qingjin; Ruan, Yongshun; Dong, Lihui; Li, Bin; Fan, Minguang

    2016-08-01

    This work is mainly focused on investigating the effects of different doped metal cations on the formation of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) composite oxides and their physicochemical and catalytic properties for NO reduction by CO as a model reaction. The obtained samples were characterized by using N2 physisorption, X-ray diffraction, laser Raman spectroscopy, UV/Vis diffuse reflectance spectroscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by hydrogen and by oxygen (H2 -TPR and O2 -TPD), in situ diffuse reflectance infrared Fourier transform spectroscopy, and the NO+CO model reaction. The results imply that the introduction of M(x+) into the lattice of CeO2 increases the specific surface area and pore volume, especially for variable valence metal cations, and enhances the catalytic performance to a great extent. In this regard, increases in the oxygen vacancies, reduction properties, and chemisorbed O2 (-) (and/or O(-) ) species of these Ce20 M1 Ox composite oxides (M refers to variable valence metals) play significant roles in this reaction. Among the samples, Ce20 Cr1 Ox exhibited the best catalytic performance, mainly because it has the best reducibility and more chemisorbed oxygen, and significant reasons for these attributes may be closely related to favorable synergistic interactions of the vacancies and near-surface Ce(3+) and Cr(3+) . Finally, a possible reaction mechanism was tentatively proposed to understand the reactions.

  5. Design of Multichannel Osmium-Based Metalloreceptor for Anions and Cations by Taking Profit from Metal-Ligand Interaction and Construction of Molecular Keypad Lock and Memory Device.

    Science.gov (United States)

    Karmakar, Srikanta; Mardanya, Sourav; Pal, Poulami; Baitalik, Sujoy

    2015-12-21

    A polypyridylimidazole-based bifunctional Os(II) complex of the type [(bpy)2Os(tpy-Hbzim-dipy)](ClO4)2 (1), where tpy-Hbzim-dipy = 4'-[4-(4,5-dipyridin-2-yl-1H-imidazol-2-yl)-phenyl]-2,2';6',2″-terpyridine and bpy = 2,2'-bipyridine, has been synthesized and structurally characterized for the construction of multifunctional logic devices. After coordination of an [Os(bpy)2](2+) unit to one of the two bidentate chelating sites, the complex offers a terpyridine motif for binding with cationic guests and an imidazole moiety for interacting with selective anionic species. Consequently, the anion- and cation-binding aspects of the metallorecptor were examined in solution and in the solid state by different spectroscopic and electrochemical methods. The complex behaves as a bifunctional sensor for F(-), AcO(-), CN(-), Fe(2+), and Cu(2+) ions in acetonitrile, whereas it is a highly selective chromogenic chemosensor for only CN(-) and Fe(2+) ions in water. Based on various output signals with a particular set of anionic and cationic inputs, the complex mimics the functions of two-input INHIBIT, OR, NOR, and XNOR logic gates, as well as three-input NOR logic behavior. More importantly, the complicated functions of a keypad lock and memory device were also nicely demonstrated by the complex. Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations also provide a rationale for properly understanding and interpreting the experimentally observed results. PMID:26687380

  6. Metais pesados em amostras biológicas de bovinos Heavy metals in cattle biological samples

    Directory of Open Access Journals (Sweden)

    Maria Verônica de Souza

    2009-09-01

    Full Text Available O objetivo deste trabalho foi determinar a concentração de metais pesados no sangue (Pb, Ni e Cd, soro (Cu e Zn, pelo e leite (Pb, Ni, Cd, Cu e Zn de bovinos criados em área industrializada (com siderúrgicas e não-industrial do Estado de Minas Gerais, em amostras coletadas em duas épocas (inverno e verão, buscando avaliar a contaminação em animais em função do ambiente de exposição e da estação do ano. O local de criação dos animais afetou significativamente somente a concentração de Cu obtida nas amostras de soro, com maiores valores determinados no grupo de bovinos da região industrializada. A época de amostragem afetou a concentração dos metais Cu (soro, Zn (soro e leite, Pb (sangue e Cd (sangue e pelo, com as determinações efetuadas no verão proporcionando maiores teores do que as executadas no inverno, à exceção do Cd avaliado no pelo. Interações significativas (PThe aim of this research was to determine the heavy metals concentration in blood (Pb, Ni and Cd, serum (Cu and Zn, hair and milk (Pb, Ni, Cd, Cu and Zn of cattle raised in industrial (with steel mill and non-industrial areas in Minas Gerais, Brazil. The samples were collected during summer and winter, aiming to verify animals contamination related to environment and year season. The environment significantly influenced the concentration of Cu obtained on serum samples, with higher values for cattle from the industrialized area. The sampling time affected the concentration of Cu (serum, Zn (serum and milk, Pb (blood and Cd (blood and hair, with higher values for summer, except for Cd measured on hair. Meaningful interactions (P<0.05 between environment and year season were identified for Cu (hair and milk, Zn (hair and Ni (serum, hair and milk. The results obtained show that the presence of steel mills in a determined area does not mean, necessarily that higher concentration of heavy metals will be found in cattle biological matrices. The seasonality

  7. Preconcentration and determination of heavy metals in water, sediment and biological samples

    Directory of Open Access Journals (Sweden)

    Shirkhanloo Hamid

    2011-01-01

    Full Text Available In this study, a simple, sensitive and accurate column preconcentration method was developed for the determination of Cd, Cu and Pb ions in river water, urine and sediment samples by flame atomic absorption spectrometry. The procedure is based on the retention of the analytes on a mixed cellulose ester membrane (MCEM column from buffered sample solutions and then their elution from the column with nitric acid. Several parameters, such as pH of the sample solution, volume of the sample and eluent and flow rates of the sample were evaluated. The effects of diverse ions on the preconcentration were also investigated. The recoveries were >95 %. The developed method was applied to the determination of trace metal ions in river water, urine and sediment samples, with satisfactory results. The 3δ detection limits for Cu, Pb and Cd were found to be 2, 3 and 0.2 μg dm−3, respectively. The presented procedure was successfully applied for determination of the copper, lead and cadmium contents in real samples, i.e., river water and biological samples.

  8. Complexation of biological ligands with lanthanides(III) for MRI: Structure, thermodynamic and methods; Complexation des cations lanthanides trivalents par des ligands d'origine biologique pour l'IRM: Structure, thermodynamique et methodes

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, C

    2006-07-15

    New cyclic ligands derived from sugars and amino-acids form a scaffold carrying a coordination sphere of oxygen atoms suitable to complex Ln(III) ions. In spite of their rather low molecular weights, the complexes display surprisingly high relaxivity values, especially at high field. The ACX and BCX ligands, which are acidic derivatives of modified and cyclo-dextrins, form mono and bimetallic complexes with Ln(III). The LnACX and LnBCX complexes show affinities towards Ln(III) similar to those of tri-acidic ligands. In the bimetallic Lu2ACX complex, the cations are deeply embedded in the cavity of the ligand, as shown by the X-ray structure. In aqueous solution, the number of water molecules coordinated to the cation in the LnACX complex depends on the nature and concentration of the alkali ions of the supporting electrolyte, as shown by luminescence and relaxometric measurements. There is only one water molecule coordinated in the LnBCX complex, which enables us to highlight an important second sphere contribution to relaxivity. The NMR study of the RAFT peptidic ligand shows the complexation of Ln(III), with an affinity similar to those of natural ligands derived from calmodulin. The relaxometric study also shows an important second sphere contribution to relaxivity. To better understand the intricate molecular factors affecting relaxivity, we developed new relaxometric methods based on probe solutes. These methods allow us to determine the charge of the complex, weak affinity constants, trans-metallation constants, and the electronic relaxation rate. (author)

  9. Do Cation-π Interactions Exist in Bacteriorhodopsin

    Institute of Scientific and Technical Information of China (English)

    HU Kun-Sheng; WANG Guang-Yu; HE Jin-An

    2001-01-01

    Metal ions are essential to the structure and physiological functions of bacteriorhodopsin. Experimental evidence suggests the existence of specific cation binding to the negatively charged groups of Asp85 and Asp212 via an electrostatic interaction. However, only using electrostatic force is not enough to explain the role of the metal cations because the carboxylate of Asp85 is well known to be protonated in the M intermediate. Considering the presence of some aromatic amino acid residues in the vicinity of the retinal pocket, the existence of cation-π interactions between the metal cation and aromatic amino acid residues is suggested. Obviously, introduction of this kind of interaction is conducive to understanding the effects of the metal cations and aromatic amino acid residues inside the protein on the structural stability and proton pumping of bacteriorhodopsin.

  10. Mechanism of Electrochemical Catalytic Treatment of Phenol Wastewater Catalyzed by Metal Ion Supported on Cation Exchange Resin%苯酚水在离子交换树脂电化学降解中的机理研究

    Institute of Scientific and Technical Information of China (English)

    王莹; 侯党社; 韩莉萍

    2011-01-01

    The electrochemical oxidation of phenol in synthetic wastewater catalyzed by metal ion supported on cation exchange resin has been investigated.It was found that in the process of the phenol oxidation, hydroxyl radicals and Fe were all attribute to the phenol oxidation.%本文以负载金属的离子交换树脂为催化剂,采用电化学降解的方法研究了苯酚水的降解机理.研究表明苯酚水在离子交换树脂电化学降解中可能是由羟基自由基、金属氧化物、金属离子、电絮凝等协同作用下进行降解.

  11. N,N',N"-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane (Deofix) - a high-affinity, high-specificity chelator for first transition series metal cations with significant deodorant, antimicrobial, and antioxidant activity.

    Science.gov (United States)

    Laden, Karl; Zaklad, Haim; Simhon, Elliot D; Klein, Joseph Y; Cyjon, Rosa L; Winchell, Harry S

    2003-01-01

    Deofix, N,N',N"-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane, is a high-affinity, high-specificity chelator for first transition series cations such as iron, zinc, manganese, and copper. A 1% solution in 50% ethanol was found to be significantly better at reducing underarm malodor than a solution of 0.3% Triclosan in 50% ethanol. Compared to a 50% alcohol control, Deofix was found to produce a significant reduction in malodor for at least 48 hours. Deofix appears to work by reducing the concentration of first transition series metal ions below the levels needed for microbial cell reproduction and by inhibiting oxidative processes by interfering with catalytic formation of free radicals. Deofix has very low levels of toxicity when measured via a number of screening techniques.

  12. Biologic

    CERN Document Server

    Kauffman, L H

    2002-01-01

    In this paper we explore the boundary between biology and the study of formal systems (logic). In the end, we arrive at a summary formalism, a chapter in "boundary mathematics" where there are not only containers but also extainers ><, entities open to interaction and distinguishing the space that they are not. The boundary algebra of containers and extainers is to biologic what boolean algebra is to classical logic. We show how this formalism encompasses significant parts of the logic of DNA replication, the Dirac formalism for quantum mechanics, formalisms for protein folding and the basic structure of the Temperley Lieb algebra at the foundations of topological invariants of knots and links.

  13. Biosorption of heavy metals in a photo-rotating biological contactor--a batch process study.

    Science.gov (United States)

    Orandi, Sanaz; Lewis, David M

    2013-06-01

    Metal removal potential of indigenous mining microorganisms from acid mine drainage (AMD) has been well recognised in situ at mine sites. However, their removal capacity requires to be investigated for AMD treatment. In the reported study, the capacity of an indigenous AMD microbial consortium dominated with Klebsormidium sp., immobilised in a photo-rotating biological contactor (PRBC), was investigated for removing various elements from a multi-ion synthetic AMD. The synthetic AMD was composed of major (Cu, Mn, Mg, Zn, Ca, Na, Ni) and trace elements (Fe, Al, Cr, Co, Se, Ag, Mo) at initial concentrations of 2 to 100 mg/L and 0.005 to 1 mg/L, respectively. The PRBC was operated for two 7-day batch periods under pH conditions of 3 and 5. The maximum removal was observed after 3 and 6 days at pH 3 and 5, respectively. Daily water analysis data demonstrated the ability of the algal-microbial biofilm to remove an overall average of 25-40 % of the major elements at pH 3 in the order of Na > Cu > Ca > Mg > Mn > Ni > Zn, whereas a higher removal (35-50 %) was observed at pH 5 in the order of Cu > Mn > Mg > Ca > Ni > Zn > Na. The removal efficiency of the system for trace elements varied extensively between 3 and 80 % at the both pH conditions. The batch data results demonstrated the ability for indigenous AMD algal-microbial biofilm for removing a variety of elements from AMD in a PRBC. The work presents the potential for further development and scale-up to use PBRC inoculated with AMD microorganisms at mine sites for first or secondary AMD treatment.

  14. Redox-active on-surface polymerization of single-site divalent cations from pure metals by a ketone-functionalized phenanthroline

    Energy Technology Data Exchange (ETDEWEB)

    Skomski, Daniel; Tempas, Christopher D.; Bukowski, Gregory S.; Smith, Kevin A.; Tait, Steven L., E-mail: tait@indiana.edu [Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, Indiana 47405 (United States)

    2015-03-14

    Metallic iron, chromium, or platinum mixing with a ketone-functionalized phenanthroline ligand on a single crystal gold surface demonstrates redox activity to a well-defined oxidation state and assembly into thermally stable, one dimensional, polymeric chains. The diverging ligand geometry incorporates redox-active sub-units and bi-dentate binding sites. The gold surface provides a stable adsorption environment and directs growth of the polymeric chains, but is inert with regard to the redox chemistry. These systems are characterized by scanning tunnelling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy under ultra-high vacuum conditions. The relative propensity of the metals to interact with the ketone group is examined, and it is found that Fe and Cr more readily complex the ligand than Pt. The formation and stabilization of well-defined transition metal single-sites at surfaces may open new routes to achieve higher selectivity in heterogeneous catalysts.

  15. Development of metal cation compound-loaded S-doped TiO2 photocatalysts having a rutile phase under visible light

    OpenAIRE

    Ohno, T; Murakami, N.; Tsubota, T.; Nishimura, H.

    2008-01-01

    We have synthesized S (S4+)-doped TiO2 photocatalysts having a rutile phase. Rutile S-doped TiO2 photocatalysts loaded with metal ion compounds (Fe3+, Rh3+, Cu2+, Co3+, Ni2+, Cr3+) have also been prepared (S-doped TiO2-Mn+). The metal ions were adsorbed on the surfaces of S-doped TiO2 nanoparticles by impregnation methods (IM) or photodeposition methods (PH). The photocatalytic activities of S-doped TiO2 for oxidation of acetaldehyde in gas phase were drastically improved after adsorbing trea...

  16. Quantifying restoration success and recovery in a metal-polluted stream: A 17-year assessment of physicochemical and biological responses

    Science.gov (United States)

    Clements, W.H.; Vieira, N.K.M.; Church, S.E.

    2010-01-01

    Evaluating the effectiveness of stream restoration is often challenging because of the lack of pre-treatment data, narrow focus on physicochemical measures and insufficient post-restoration monitoring. Even when these fundamental elements are present, quantifying restoration success is difficult because of the challenges associated with distinguishing treatment effects from seasonal variation, episodic events and long-term climatic changes.2. We report results of one of the most comprehensive and continuous records of physical, chemical and biological data available to assess restoration success for a stream ecosystem in North America. Over a 17 year period we measured seasonal and annual changes in metal concentrations, physicochemical characteristics, macroinvertebrate communities, and brown trout Salmo trutta populations in the Arkansas River, a metal-contaminated stream in Colorado, USA.3. Although we observed significant improvements in water quality after treatment, the effectiveness of restoration varied temporally, spatially and among biological response variables. The fastest recovery was observed at stations where restoration eliminated point sources of metal contamination. Recovery of macroinvertebrates was significantly delayed at some stations because of residual sediment contamination and because extreme seasonal and episodic variation in metal concentrations prevented recolonization by sensitive species. Synthesis and applications. Because recovery trajectories after the removal of a stressor are often complex or nonlinear, long-term studies are necessary to assess restoration success within the context of episodic events and changes in regional climate. The observed variation in recovery among chemical and biological endpoints highlights the importance of developing objective criteria to assess restoration success. Although the rapid response of macroinvertebrates to reduced metal concentrations is encouraging, we have previously demonstrated that

  17. Effects of Tabriz petrochemicals’ biological sludge on heavy metals concentration in soil and spring barley in greenhouse conditions

    Directory of Open Access Journals (Sweden)

    Sh. Oustan

    2012-03-01

    Full Text Available Utilizing sewage sludge as a source of cheap fertilizer and rich in nutrients is common in some parts of Iran. But, too much application causes accumulation of heavy metals in soil, which results in soil pollution and transfer of this pollution to food chain and endangers human and animal health. The aim of this research was to investigate the effect of biological sludge of Tabriz petrochemicals complex on some heavy metals concentration in spring barley grown in a calcareous soil after 6 months of incubation. The experiment was conducted in greenhouse conditions with 5 levels of 0 (control, 25, 50, 75 and 100 ton/ha sewage sludge, in three replications, based on complete randomized blocks design. Soil analysis showed that application of biological sludge significantly increased DTPA extractable Fe, Zn, Mn, Cu and Cd (except 25 ton/ha treatment compared to the control. The results of plant analysis showed an increase of Fe, Zn and Mn in shoots and Zn and Mn in roots, compared to the control. But elevation of root Fe content was not significant. The amount of Cu and Cd in shoots and roots was below the detection limit of the instrument. Overall, it was concluded that although the application of biological sludge increased the content of heavy metals in soil, but its effect on concentration of toxic elements, such as Cd, in plants was not significant.

  18. Comprehensive biological effects of a complex field poly-metallic pollution gradient on the New Zealand mudsnail Potamopyrgus antipodarum (Gray)

    International Nuclear Information System (INIS)

    The Lot River is known to be contaminated by metals, mainly cadmium and zinc, due to a former Zn ore treatment plant in the watershed of the Riou-Mort, a tributary of the Lot River. Many studies have been performed to characterize contamination, but few have assessed its consequences on the biological responses of organisms along the gradient. We exposed adult and juvenile New Zealand freshwater mudsnails Potamopyrgus antipodarum at several sites along the gradient of metal contamination for 28 days. Biological responses were monitored at different levels: individual (survival, growth and fecundity), tissue and biochemical (energy status and vertebrate-like sex steroid levels) to better understand the toxicity mechanisms involved. Accumulation of Cd and Zn was high during exposure. Most of the biological effects observed could be linked to this contamination and were concentration-dependent. Histological lesions of the digestive gland were observed, with hypertrophy of calcium cells and vacuolization of digestive cells. Such effects are likely to explain the decrease of energy status (triglycerides and proteins), juvenile growth and adult fecundity observed at the most polluted site. However the magnitude of the fall in fecundity cannot be attributed only to these tissular effects, indicating another mode of action of Cd or possible confounding factors. Steroid accumulation in snails indicated only organic pollution. Histopathological effects proved the most sensitive endpoint to metal (Cd and Zn) contamination.

  19. Comprehensive biological effects of a complex field poly-metallic pollution gradient on the New Zealand mudsnail Potamopyrgus antipodarum (Gray)

    Energy Technology Data Exchange (ETDEWEB)

    Gust, M., E-mail: marion.gust@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); AgroPariTech ENGREF, 19 avenue du Maine, F 75732 Paris (France); Buronfosse, T., E-mail: thierry.buronfosse@inserm.fr [Universite de Lyon, Laboratoire d' endocrinologie, Ecole Nationale Veterinaire de Lyon, avenue Bourgelat, 69280 Marcy l' Etoile (France); Geffard, O., E-mail: olivier.geffard@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); Coquery, M., E-mail: marina.coquery@cemagref.fr [Cemagref, UR MALY, Laboratoire d' analyses physico-chimiques des milieux aquatiques, 3b quai Chauveau, 69009 Lyon (France); Mons, R., E-mail: raphael.mons@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); Abbaci, K., E-mail: khedidja.abbaci@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); Giamberini, L., E-mail: giamb@sciences.univ-metz.fr [Laboratoire des interactions Ecotoxicologie, Biodiversite, Ecosystemes, CNRS UMR 7146, campus Bridoux, 57000 Metz (France); Garric, J., E-mail: jeanne.garric@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France)

    2011-01-17

    The Lot River is known to be contaminated by metals, mainly cadmium and zinc, due to a former Zn ore treatment plant in the watershed of the Riou-Mort, a tributary of the Lot River. Many studies have been performed to characterize contamination, but few have assessed its consequences on the biological responses of organisms along the gradient. We exposed adult and juvenile New Zealand freshwater mudsnails Potamopyrgus antipodarum at several sites along the gradient of metal contamination for 28 days. Biological responses were monitored at different levels: individual (survival, growth and fecundity), tissue and biochemical (energy status and vertebrate-like sex steroid levels) to better understand the toxicity mechanisms involved. Accumulation of Cd and Zn was high during exposure. Most of the biological effects observed could be linked to this contamination and were concentration-dependent. Histological lesions of the digestive gland were observed, with hypertrophy of calcium cells and vacuolization of digestive cells. Such effects are likely to explain the decrease of energy status (triglycerides and proteins), juvenile growth and adult fecundity observed at the most polluted site. However the magnitude of the fall in fecundity cannot be attributed only to these tissular effects, indicating another mode of action of Cd or possible confounding factors. Steroid accumulation in snails indicated only organic pollution. Histopathological effects proved the most sensitive endpoint to metal (Cd and Zn) contamination.

  20. Influence of Nano-Crystal Metals on Texture and Biological Properties of Water Soluble Polysaccharides of Medicinal Plants

    Science.gov (United States)

    Churilov, G.; Ivanycheva, J.; Kiryshin, V.

    2015-11-01

    When treating the plants seeds with nano-materials there are some quality and quantity changes of polysaccharides, the molecular mass increase and monosaccharides change that leads to the increase of physiological and pharmacological activity of carbohydrates got from medicinal plants. We have got water soluble polysaccharides and nano-metals combinations containing 0.000165-0.000017 mg/dm3 of the metal. In a case of induced anemia the blood composition has practically restored on the 10th day of the treatment with nanocomposites. The use of pectin polysaccharides (that are attributed to modifiers of biological respond) to get nano-structured materials seems to be actual relative to their physiological activity (radio nuclides persorption, heavy metals ions, bacteria cells and their toxins; lipids metabolism normalization; bowels secreting and motor functions activation and modulation of the endocrine system.

  1. Mitigation of heavy metals in different vegetables through biological washing techniques

    OpenAIRE

    Muhammad Umair Sattar; Faqir Muhammad Anjum; Aysha Sameen

    2015-01-01

    Availability of nutritious and healthy food is the foremost challenging issue in all over the word. Vegetables are essential part in human diet and considered as natural reserves of nutrients gifted by Almighty Allah to human beings. Heavy metals are among the most toxic food pollutants and their intake through diet leads to several disorders. The sources of heavy metal contamination include waste water irrigation, industrial emissions, transportation and application of metal-based pesticides...

  2. Synthesis and characterization of a new cation exchanger-zirconium(IV)iodotungstate: Separation and determination of metal ion contents of synthetic mixtures, pharmaceutical preparations and standard reference material

    International Nuclear Information System (INIS)

    Samples of zirconium(IV)iodotungstate have been synthesized under varying mixing order and ratios of aqueous solution of potassium iodate, sodium tungstate and zirconium oxychloride at pH 1. A tentative formula was proposed on the basis of chemical composition, FTIR and thermogravimetric studies. The material shows a capacity of 0.68 meq g-1 (for K+) which can be retained up to 200 deg. C. pH titration data reveal its monofunctional behavior. The distribution coefficient values of metal ions have been determined in various solvent systems. A number of important and analytically difficult quantitative separations of metal ions have been achieved using columns packed with this exchanger. In order to demonstrate practical utility of this material, Hg2+ and Pb2+ have been selectively separated and determined in the synthetic mixtures. Assay of Al3+ and Mg2+ in commercial tablets and analysis of lead in the standard reference material have also been attempted.

  3. Role of divalent metal cations in ATP hydrolysis catalyzed by the hepatitis C virus NS3 helicase: Magnesium provides a bridge for ATP to fuel unwinding

    OpenAIRE

    Frick, David N.; Banik, Sukalyani; Rypma, Ryan S.

    2006-01-01

    This study investigates the role of magnesium ions in coupling ATP hydrolysis to the nucleic acid unwinding catalyzed by the NS3 protein encoded by the hepatitis C virus. Analyses of steady-state ATP hydrolysis rates at various RNA and magnesium concentrations were used to determine values for the 15 dissociation constants describing the formation of a productive enzyme-metal-ATP-RNA complex and the 4 rate constants describing hydrolysis of ATP by the possible enzyme-ATP complexes. These valu...

  4. Growth of novel ceramic layers on metals via chemical and heat treatments for inducing various biological functions

    Directory of Open Access Journals (Sweden)

    Tadashi eKokubo

    2015-10-01

    Full Text Available The present authors’ systematic studies on growth of novel ceramic layers on Ti metal and its alloys by chemical and heat treatments for inducing bone-bonding bioactivity and some other biological functions are reviewed. Ti metal formed an apatite on its surface in a simulated body fluid (SBF, when heat-treated after exposure to strong acid solutions to form rutile surface layer, or to strong alkali solutions to form sodium titanate surface layer. Both types of Ti metal tightly bonded to the living bone.The alkali and heat treatment was applied to the surface Ti metal of an artificial hip joint and successfully used in the clinic since 2007. The acid and heat treatments was applied to porous Ti metal to induce osteoconductivity as well as osteoinductivity. The resulting product was successfully used in clinical trials for spinal fusion devices. For the Ti-based alloys, the alkali and heat treatment was a little modified to form calcium titanate surface layer. Bone-growth promoting Mg, Sr, and Zn ions as well as the antibacterial Ag ion were successfully incorporated into the calcium titanate layer.

  5. Growth of Novel Ceramic Layers on Metals via Chemical and Heat Treatments for Inducing Various Biological Functions.

    Science.gov (United States)

    Kokubo, Tadashi; Yamaguchi, Seiji

    2015-01-01

    The present authors' systematic studies on growth of novel ceramic layers on Ti metal and its alloys by chemical and heat treatments for inducing bone-bonding bioactivity and some other biological functions are reviewed. Ti metal formed an apatite on its surface in a simulated body fluid, when heat-treated after exposure to strong acid solutions to form rutile surface layer, or to strong alkali solutions to form sodium titanate surface layer. Both types of Ti metal tightly bonded to the living bone. The alkali and heat treatment was applied to the surface Ti metal of an artificial hip joint and successfully used in the clinic since 2007. The acid and heat treatments was applied to porous Ti metal to induce osteoconductivity as well as osteoinductivity. The resulting product was successfully used in clinical trials for spinal fusion devices. For the Ti-based alloys, the alkali and heat treatment was little modified to form calcium titanate surface layer. Bone-growth promoting Mg, Sr, and Zn ions as well as the antibacterial Ag ion were successfully incorporated into the calcium titanate layer. PMID:26579517

  6. Exploring rhizosphere bacteria of Eichhornia crassipes for metal tolerance and biological activity

    Digital Repository Service at National Institute of Oceanography (India)

    PrabhaDevi; Gomez, S.; Ribeiro, M.; Deshpande, S.A.; Singh, K.S.; DeSouza, L.

    ). Depending on the metals they tolreted (Pb, Cu, Fe, Zn. & Co), the metal tolerant bacteria were labeled as Pb-1 to Pb-3, Cu-1 to Cu-4, Fe-1 to Fe-4,Zn-1 to Zn-4, and Co-1 to Co-2. No cultures tolerated and grew in the presence of Hg and Cd. Cultures were...

  7. SYNTHESIS OF THERMALLY STABLE CARBOXYMETHYL CELLULOSE/METAL BIODEGRADABLE NANOCOMPOSITES FOR POTENTIAL BIOLOGICAL APPLICATIONS

    Science.gov (United States)

    A green approach is described that generates bulk quantities of nanocomposites containing transition metals such as Cu, Ag, In and Fe at room temperature using a biodegradable polymer carboxymethyl cellulose (CMC) by reacting respective metal salts with sodium salt of CMC in aqu...

  8. Atypical behavior in the electron capture induced dissociation of biologically relevant transition metal ion complexes of the peptide hormone oxytocin

    Science.gov (United States)

    Kleinnijenhuis, Anne J.; Mihalca, Romulus; Heeren, Ron M. A.; Heck, Albert J. R.

    2006-07-01

    Doubly protonated ions of the disulfide bond containing nonapeptide hormone oxytocin and oxytocin complexes with different transition metal ions, that have biological relevance under physiological conditions, were subjected to electron capture dissociation (ECD) to probe their structural features in the gas phase. Although, all the ECD spectra were strikingly different, typical ECD behavior was observed for complexes of the nonapeptide hormone oxytocin with Ni2+, Co2+ and Zn2+, i.e., abundant c/z' and a'/y backbone cleavages and ECD characteristic S-S and S-C bond cleavages were observed. We propose that, although in the oxytocin-transition metal ion complexes the metal ions serve as the main initial capture site, the captured electron is transferred to other sites in the complex to form a hydrogen radical, which drives the subsequent typical ECD fragmentations. The complex of oxytocin with Cu2+ displayed noticeably different ECD behavior. The fragment ions were similar to fragment ions typically observed with low-energy collision induced dissociation (CID). We propose that the electrons captured by the oxytocin-Cu2+ complex might be favorably involved in reducing the Cu2+ metal ion to Cu+. Subsequent energy redistribution would explain the observed low-energy CID-type fragmentations. Electron capture resulted also in quite different specific cleavage sites for the complexes of oxytocin with Ni2+, Co2+ and Zn2+. This is an indication for structural differences in these complexes possibly linked to their significantly different biological effects on oxytocin-receptor binding, and suggests that ECD may be used to study subtle structural differences in transition metal ion-peptide complexes.

  9. Etymology of transition metal biomolecules as a learning aid in Biological Chemistry; A etimologia de biomoleculas com metais de transicao como auxiliar na aprendizagem de Quimica Biologica

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jose A.L. da, E-mail: pcd1950@ist.utl.pt [Universidade Tecnica de Lisboa (Portugal). Instituto Superior Tecnico. Centro de Quimico Estrutural

    2013-11-01

    Numerous functional biomolecules are associated with metals, i.e. the metallobiomolecules; more specifically, some are dependent on transition metals required for several crucial biological roles. Nevertheless, their names can lead to ambiguous interpretations concerning the properties and performances of this group of biological molecules. Their etymology may be useful by providing a more perceptive insight into their features. However, etymology can lead to incongruous conclusions, requiring an especially careful approach to prevent errors. Examples illustrating these subjects shall be examined (author)

  10. Innate cation sensitivity in a semiconducting polymer.

    Science.gov (United States)

    Althagafi, Talal M; Algarni, Saud A; Grell, Martin

    2016-09-01

    Water-gated organic thin film transistors (OTFTs) using the hole transporting semiconducting polymer, poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), show an innate response of their threshold voltage to the addition of divalent metal cations to the gating water, without deliberately introducing an ion-sensitive component. A similar threshold response is shown for several divalent cations, but is absent for monovalent cations. Response is absent for transistors using the inorganic semiconductor ZnO, or the similar organic semiconductor poly(3-hexylthiophene) (rrP3HT), instead of PBTTT. We assign innate cation sensitivity to residues of the organometallic Pd(0) complex used as catalyst in PBTTT synthesis which bears strong resemblance to typical metal chelating agents. Organometallic Pd(0) residues are absent from ZnO, and also from rrP3HT which is polymerised with a different type of catalyst. However, when Pd(0) complex is deliberately added to rrP3HT casting solutions, resulting OTFTs also display threshold response to a divalent cation. PMID:27343580

  11. Biological leaching of heavy metals from a contaminated soil by Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Ren Wanxia, E-mail: ren_laura@163.com [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li Peijun, E-mail: lipeijun@iae.ac.cn [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Geng Yong; Li Xiaojun [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2009-08-15

    Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.

  12. Biological leaching of heavy metals from a contaminated soil by Aspergillus niger

    International Nuclear Information System (INIS)

    Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.

  13. A study of metal distribution from lignite fuels using trees as biological monitors.

    Science.gov (United States)

    Sawidis, T; Chettri, M K; Papaioannou, A; Zachariadis, G; Stratis, J

    2001-01-01

    Concentrations of five metals (Cd, Cu, Mn, Fe, Zn) were determined in tree leaves collected from an area with large coal-fired plants in Ptolemais, Macedonia, Greece. The analyses were carried out with flame atomic absorption spectroscopy. Mean heavy metal content in the tree leaves is, in descending order, Fe>Mn>Zn>Cu>Cd. In Populus nigra and Salix babylonica the dense piled leaves and the widespread root system are the reasons for high heavy metal uptake. Conifer trees Pinus nigra and Juniperus arizona, which have a rough leaf surface, also had elevated concentrations. Leaves with a smooth surface were less contaminated. The presence of one metal within leaf cells may reduce the uptake or toxicity of other metals. Fruits accumulated less heavy metal than the corresponding leaves. The most damaged areas are those in the direct vicinity of the coal power plants, and the rate of damage caused in the environment is affected by the main wind direction. All sampling sites in Ptolemais basin are generally more or less polluted when compared with the control site.

  14. The influence of organic structure and rare earth metal cation on the corrosion efficiency observed on AS1020 steel compared with La(4OHCin3

    Directory of Open Access Journals (Sweden)

    Marianne Seter

    2015-01-01

    Full Text Available Whilst the corrosion protection of steel in aqueous chloride environments by the rare earth inhibitor lanthanum 4-hydroxycinnamate is well known, the influence of the structural variation of the organic component as well as the nature of the metal centre has not previously been addressed. Herein we show that praseodymium 4-hydroxy cinnamate is comparable to its lanthanum counterpart in aqueous solution. On the other hand, cerium 4-hydroxycinnamate and lanthanum 2-hydroxycinnamate show poor corrosion protection performance while lanthanum 3-hydroxycinnamate provides a level of inhibition between these. These differences are shown to be related to the speciation in solution and are postulated to be linked to steric influences which are likely to affect the bonding environment within the rare earth compound itself, as well as its bonding with the steel substrate.

  15. Spectral, NLO, Fluorescence, and Biological Activity of Knoevenagel Condensate of β-Diketone Ligands and Their Metal(II Complexes

    Directory of Open Access Journals (Sweden)

    S. Sumathi

    2011-01-01

    Full Text Available Transition metal complexes of various acetylacetone-based ligands of the type ML (where M=  Cu(II, Ni(II, Co(II; L=  3-(aryl-pentane-2,4-dione have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, H1NMR, mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are nonelectrolytic in nature. Spectroscopic and other analytical data of the complexes suggest square planar geometry for copper(II, cobalt(II, and nickel(II complexes of 3-(3-phenylallylidenepentane-2,4-dione and octahedral geometry for other metal(II complexes. The redox behaviors of the copper(II complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against bacteria and fungus. The metal(II complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG efficiency of the ligands was found to have considerable effect compared to that of urea and KDP.

  16. Coordination of lanthanide cation to an Anderson type polyoxometalate anion leads to isomorphous metal-oxide based one-dimensional inorganic solids: Synthesis, crystal structure and spectroscopy

    Indian Academy of Sciences (India)

    Vaddypally Shivaiah; Tanmay Chatterjee; Samar K Das

    2014-09-01

    One-dimensional isomorphous inorganic polymers containing Anderson type heteropoly anion as a basic building unit, namely [La(H2O)7Cr(OH)6Mo6O18]·4nH2O (1), [Gd(H2O)7Cr(OH)6Mo6O18]·4nH2O (2), [Gd(H2O)7Al(OH)6Mo6O18]·4nH2O (3), and [Eu(H2O)7Al(OH)6Mo6O18]·4nH2O (4) have been synthesized and studied by the powdered X-ray diffraction, TGA, IR, electronic and ESR spectroscopy, and unambiguously by single crystal X-ray crystallography. Isomorphous compounds 1-4 are crystallized in orthorhombic system with 21 space group. The crystal structure analysis reveals a one-dimensional extended chain in which the Anderson type heteropolyanion, acting as the building unit, is linked by rare earth metal ions in a zig-zag fashion. In the crystal structure, all types of oxygens of the heteropolyanion, lattice waters, lanthanum coordinated waters are extensively involved in O—H…O hydrogen bonding interactions. Compounds are additionally characterized by UV-visible and ESR spectroscopy.

  17. Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

    Science.gov (United States)

    Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

    2016-05-01

    We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

  18. Cationically polymerizable monomers derived from renewable sources

    Energy Technology Data Exchange (ETDEWEB)

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year's research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  19. Seasonal assessment of biological indices, bioaccumulation and bioavailability of heavy metals in mussels Mytilus galloprovincialis from Algerian west coast, applied to environmental monitoring

    Directory of Open Access Journals (Sweden)

    Omar Rouane-Hacene

    2015-10-01

    Full Text Available The aim of the present work is to broaden our knowledge on the variability of trace metals in mussel tissues, focusing on seasonal fluctuations in the three different sampling sites of Algerian west coast (Oran Harbor (S1, Ain Defla (S2 and Hadjaj (S3. For this purpose, the bioavailability (metal indices and bioaccumulation (metal concentrations in soft tissues of heavy metals (Zn, Cu, Pb, and Cd, and the physiological characteristics (e.g. biological indices such as condition index (CI of mussels Mytilus galloprovincialis have been assessed and related to seasons and sites. In S1, the highest levels of metal concentrations and indices were obtained in mussels sampled in winter for Zn, Cu and Cd, but in summer for Pb. The biological indices significantly decreased in winter. In S2, the levels of concentrations and indices of all metals varied whatever the seasons, excepting in summer where the values were the lowest. In summer and spring, the biological indices were lower than in autumn and winter. The low growth of organisms in spring and summer might be correlated to the reproductive period and the low trophic level known in S2. S3, considered as a “pristine” area, showed low metal concentrations and indices, and high biological indices, reflecting the favorable physiological conditions for the mussel growth. This approach might be used in the monitoring of the quality of coastal waters and the present work provided a useful data set for Mediterranean monitoring network.

  20. Liposomes as biological carriers: new therapeutic approaches to metal toxicity and malignant tumors

    International Nuclear Information System (INIS)

    This section contains a summary of research on the development of a new technique of drug encapsulation within liposomes to deliver metal chelating agents and antitumor drugs to specified target organs in order to enhance the therapeutic effect and reduce the effective dosage and toxicity of the drug. It has been demonstrated, that by manipulating the size and lipid composition of liposomes, selective delivery of liposome-encapsulated metal chelators to either the parenchymal or the Kupffer cells of the liver can be achieved

  1. Cluster-Continuum Calculations of Hydration Free Energies of Anions and Group 12 Divalent Cations

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hao-Bo [ORNL; Liang, Liyuan [ORNL; Parks, Jerry M [ORNL; Smith, Jeremy C [ORNL; Riccardi, Demian M [ORNL; Gu, Baohua [ORNL

    2013-01-01

    Understanding aqueous phase processes involving group 12 metal cations is relevant to both environmental and biological sciences. Here, quantum chemical methods and polarizable continuum models are used to compute the hydration free energies of a series of divalent group 12 metal cations (Zn2+, Cd2+, and Hg2+) together with Cu2+ and the anions OH , SH , Cl , and F . A cluster-continuum method is employed, in which gas-phase clusters of the ion and explicit solvent molecules are immersed in a dielectric continuum. Two approaches to define the size of the solute-water cluster are compared, in which the number of explicit waters used is either held constant or determined variationally as that of the most favorable hydration free energy. Results obtained with various polarizable continuum models are also presented. Each leg of the relevant thermodynamic cycle is analyzed in detail to determine how different contributions yield the observed mean signed error (MSE) and the standard deviation of the error (STDEV) between theory and experiment. The use of a constant number of water molecules for each set of ions is found to lead to predicted relative trends that benefit from error cancellation. Overall, the best results are obtained with MP2 and the Solvent Model D polarizable continuum model (SMD), with eight explicit water molecules for anions and ten for the metal cations, yielding a STDEV of 2.3 kcal/mol and MSE of 0.9 kcal/mol between theoretical to experimental hydration free energies, which range from -72.4 kcal/mol for SH to -505.9 kcal/mol for Cu2+. Using B3PW91 with DFT-D3 dispersion corrections (B3PW91-D) and SMD yields a STDEV of 3.3 kcal mol 1 and MSE of 1.6 kcal/mol, to which adding MP2 corrections from smaller divalent metal ion water molecule clusters yields very good agreement with the full MP2 results. Using B3PW91-D and SMD, with two explicit water molecules for anions and six for divalent metal cations also yields reasonable agreement with experiment

  2. Syntheses and characterization of energetic compounds constructed from alkaline earth metal cations (Sr and Ba) and 1,2-bis(tetrazol-5-yl)ethane

    International Nuclear Information System (INIS)

    Two new energetic compounds, [M(BTE)(H2O)5]n (M=Sr(1), Ba(2)) [H2BTE=1,2-bis(tetrazol-5-yl)ethane], have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that they are isomorphous and exhibit 2D (4,4) net framework, generated by 4-connected Sr2(H2O)10/Ba2(H2O)10 SBUs linked up by two independent binding modes of H2BTE, and the resulting 2D structure is interconnected by hydrogen-bond and strong face to face π-π stacking interactions between two tetrazole rings to lead to a 3D supramolecular architecture. DSC measurements show that they have significant catalytic effects on thermal decomposition of ammonium perchlorate. Moreover, the photoluminescence properties, thermogravimetric analyses, and flame colors of the as-prepared compounds are also investigated in this paper. - Graphical abstract: Two novel 2D isomorphous alkaline earth metal complexes were assembled by 4-connected Sr2(H2O)10/Ba2(H2O)10 SBUs and two independent binding modes of H2BTE ligands, and the catalytic performances toward thermal decomposition of ammonium perchlorate and photoluminescent properties of them were investigated. Highlights: → Two novel alkaline earth energetic coordination polymers have been prepared.→ Both structures are layered based on 4-connected Sr2(H2O)10/Ba2(H2O)10 SBUs and two distinct H2BTE coordination modes.→ The dehydrated products of the compounds possess good thermostability and significant catalytic effects on thermal decomposition of AP.

  3. Synthesis, physico-chemical characterization and biological activity of 2-aminobenzimidazole complexes with different metal ions

    Directory of Open Access Journals (Sweden)

    Podunavac-Kuzmanović Sanja O.

    2004-01-01

    Full Text Available Complexes of 2-aminobenzimidazole (L with nitrates of cobalt(II nickel(II, copper (II, zinc(II and silver(I were synthesized. The molar ratio metal:ligand in the reaction of the complex formation was 1:2. It should be noticed, that the reaction of all the metal salts yielded bis(ligand complexes of the general formula M(L2(NO32 × nH2O (M=Co, Ni Cu, Zn or Ag; n=0, 1, 2 or 6. The complexes were characterized by elemental analysis of the metal, molar conductivity, magnetic susceptibility measurements and IR spectra. Co(II, Ni(II and Cu(II complexes behave as non-electrolytes, whilst Zn(II and Ag(I are 1:1 electrolytes. Cu(II complex has a square-planar stereochemistry, Ag(I complex is linear, whilst the Co(II, Ni(II and Zn(II complexes have a tetrahedral configuration. In all the complexes ligand is coordinated by participation of the pyridine nitrogen of the benzimidazole ring. The antimicrobial activity of the ligand and its complexes against Pseudomonas aeruginosa, Bacillus sp. Staphylococcus aureus and Saccharomyces cerevisiae was investigated. The effect of metal on the ligand antimicrobial activity is discussed.

  4. Biological recovery of metals, sulfur and water in the mining and metallurgical industry

    NARCIS (Netherlands)

    Weijma, J.; Copini, C.F.M.; Buisman, C.J.N.; Schultz, C.E.

    2002-01-01

    Metals of particular interest in acid mine drainage and industrial wastewaters include copper, zinc, cadmium, arsenic, manganese, aluminum, lead, nickel, silver, mercury, chromium, uranium and iron, in a concentration that can range from 106 to 102 g/l. The composition of such wastewater reflects th

  5. Heavy-metal air pollution study using biological indicators and nuclear analytical methods

    International Nuclear Information System (INIS)

    The development of industry and the increase in vehicle road traffic are responsible for the ever-growing environmental pollution by toxic elements. Some biological organisms strongly accumulate certain heavy toxic elements and thus can be considered as indicators of the environmental pollution. In this work different types of biological indicators were collected in almost all main cities and industrial zones of Vietnam. They were subsequently analysed by different modern analytical methods. The concentration of different elements and their correlation matrices may provide valuable information on the nature and sources of pollution (author)

  6. BIOLOGICAL REMOVAL OF LEAD BY BACILLUS SP. OBTAINED FROM METAL CONTAMINATED INDUSTRIAL AREA

    Directory of Open Access Journals (Sweden)

    Rinoy Varghese

    2012-10-01

    Full Text Available In the present study bacterial strains were isolated from soil, sediment and water samples of metal polluted environment. As a result, various 164 heterotrophic bacterial strains were isolated and studied the multiple metal tolerance profile and lead bioaccumulation potentiality. We also analyze the metal contamination of the selected study area. The average abundance order of heavy metal contents in soil, water and sediments were Zn>Cu>Pb>Cd. Zinc concentration ranged from 39.832µg/L to 310.24µg/L in water, 12.81µg/g to 407.53µg/g in soil and 81.06µg/g to 829.54µg/g in sediment; copper concentration from 25.54µg/L to 66.29µg/L in water, 8.22µg/g to 73.11µg/g in soil and 32.28µg/g to 600.61µg/g in sediment; lead concentration from 8.09µg/L to 25.23µg/L in water, 5.31µg/g to 73.11µg/g in soil and 1.02µg/g to 60.14µg/g in sediment and cadmium concentration ranged from 39.832µg/L to 310.24µg/L in water, 12.81µg/g to 407.53µg/g in soil and 81.06µg/g to 829.54µg/g in sediment. Metal resistance studies of the bacterial isolates revealed that out of 164 isolates collected about 45% of the isolates showed very high tolerance (>6000µg/ml to lead. Tolerance to Cd and Zn were relatively low (<500 µg/ml. Resistance to Ni and Cr were in between 1000µg/ml - 1500µg/ml. A total of 18 bacterial genera were recorded from the study area; ten genera from soil and 11 from water, while only 5 bacterial genera were recorded from sediment samples. Bioaccumulation studies revealed that with increase in time, the biomass of the selected bacterial isolates increased. Correspondingly, with increase in biomass, the heavy metal bioaccumulation was also increased. In lead removal studies, around 50% of the lead in the experimental flasks was reduced by Bacillus sp. In control flask, only 5% metal reduction occurs. The obtained results showed that the selected Bacillus sp. is good bioaccumulation medium for lead ions.

  7. Cations bind only weakly to amides in aqueous solutions.

    Science.gov (United States)

    Okur, Halil I; Kherb, Jaibir; Cremer, Paul S

    2013-04-01

    We investigated salt interactions with butyramide as a simple mimic of cation interactions with protein backbones. The experiments were performed in aqueous metal chloride solutions using two spectroscopic techniques. In the first, which provided information about contact pair formation, the response of the amide I band to the nature and concentration of salt was monitored in bulk aqueous solutions via attenuated total reflection Fourier transform infrared spectroscopy. It was found that molar concentrations of well-hydrated metal cations (Ca(2+), Mg(2+), Li(+)) led to the rise of a peak assigned to metal cation-bound amides (1645 cm(-1)) and a decrease in the peak associated with purely water-bound amides (1620 cm(-1)). In a complementary set of experiments, the effect of cation identity and concentration was investigated at the air/butyramide/water interface via vibrational sum frequency spectroscopy. In these studies, metal ion-amide binding led to the ordering of the adjacent water layer. Such experiments were sensitive to the interfacial partitioning of cations in either a contact pair with the amide or as a solvent separated pair. In both experiments, the ordering of the interactions of the cations was: Ca(2+) > Mg(2+) > Li(+) > Na(+) ≈ K(+). This is a direct cationic Hofmeister series. Even for Ca(2+), however, the apparent equilibrium dissociation constant of the cation with the amide carbonyl oxygen was no tighter than ∼8.5 M. For Na(+) and K(+), no evidence was found for any binding. As such, the interactions of metal cations with amides are far weaker than the analogous binding of weakly hydrated anions.

  8. Use of mass spectrometry techniques for the characterization of metal bound to proteins (metallomics) in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Ariza, J.L.; Garcia-Barrera, T.; Lorenzo, F.; Bernal, V.; Villegas, M.J.; Oliveira, V

    2004-10-25

    The need to determine the individual chemical species (speciation), especially when they are known to have a differential action and behavior in relation to toxicity, mobility, or bioavailability, is discussed. The analytical approaches for small mass metal species characterization, as well as sample treatment and storage, is now well established on the basis of chromatographic-atomic detector combinations. The description of a new scenario centered on endogenous and exogenous metallic species in biological systems, bioactive macromolecules, such as proteins, DNA restriction fragments, phytochelatins, metallothioneins and others is fulfilled. Many of these systems are not well known at present and require a new generation of analytical tools that substitute the traditional atomic detectors based in the use of photons (atomic absorption spectrometry (AAS), flame photoionization detector (FPD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), atomic fluorescence spectroscopy (AFS)) by mass detectors (mass spectrometry (MS) and inductively coupled plasma-mass spectrometry (ICP-MS)) that characterize ions. The photonic analytical tool is now being substituted by the ionic paradigm. Many cases related to biological molecules involving proteins and multiprotein systems, in which metals frequently participate (metallomics) are described, and a generic metallomics analytical approach is proposed for the identification and quantification of metalloproteins, and other metallomacromolecules present in life systems, on the basis of three experimental focuses: (i) a separation technique - selectivity component; (ii) an element-high sensitivity detector--sensitivity component; and (iii) a molecule-specific detector, generally based on mass spectrometry-structural component. This multiplexed analytical approach brings together both elemental and molecular detectors for easy metalloproteins identification. Finally, the possibilities of the metallomics approach in

  9. Redox potential tuning by redox-inactive cations in nature's water oxidizing catalyst and synthetic analogues.

    Science.gov (United States)

    Krewald, Vera; Neese, Frank; Pantazis, Dimitrios A

    2016-04-28

    The redox potential of synthetic oligonuclear transition metal complexes has been shown to correlate with the Lewis acidity of a redox-inactive cation connected to the redox-active transition metals of the cluster via oxo or hydroxo bridges. Such heterometallic clusters are important cofactors in many metalloenzymes, where it is speculated that the redox-inactive constituent ion of the cluster serves to optimize its redox potential for electron transfer or catalysis. A principal example is the oxygen-evolving complex in photosystem II of natural photosynthesis, a Mn4CaO5 cofactor that oxidizes water into dioxygen, protons and electrons. Calcium is critical for catalytic function, but its precise role is not yet established. In analogy to synthetic complexes it has been suggested that Ca(2+) fine-tunes the redox potential of the manganese cluster. Here we evaluate this hypothesis by computing the relative redox potentials of substituted derivatives of the oxygen-evolving complex with the cations Sr(2+), Gd(3+), Cd(2+), Zn(2+), Mg(2+), Sc(3+), Na(+) and Y(3+) for two sequential transitions of its catalytic cycle. The theoretical approach is validated with a series of experimentally well-characterized Mn3AO4 cubane complexes that are structural mimics of the enzymatic cluster. Our results reproduce perfectly the experimentally observed correlation between the redox potential and the Lewis acidities of redox-inactive cations for the synthetic complexes. However, it is conclusively demonstrated that this correlation does not hold for the oxygen evolving complex. In the enzyme the redox potential of the cluster only responds to the charge of the redox-inactive cations and remains otherwise insensitive to their precise identity, precluding redox-tuning of the metal cluster as a primary role for Ca(2+) in biological water oxidation.

  10. 阳离子生物蛋白衍生物固色剂的合成及应用%Synthesis and application of cationic biological protein derivative fixing agent

    Institute of Scientific and Technical Information of China (English)

    刘元军; 赵晓明; 梁腾隆

    2016-01-01

    A quaternary ammonium salt cationic biological protein derivative fixing agent (WLS- 20) was prepared using waste feather protein and self- made reactive cationic crosslinking modification agent WLS as raw materials, which was applied in the fixation post- treatment of reactive dyed cotton fabric. Using white cloth staining degree (K/S value) of soaping post- treatment and soaping fastness as evaluation indexes, the ef⁃fects of mass ratio of abandoned feather protein and WLS, alkali agent dosage, reaction temperature and reac⁃tion time on the fixation result were investigated. The optimum synthesis conditions of fixing agent WLS- 20 was determined: the mass ratio of feather protein and WLS was 1∶16, sodium hydroxide dosage was 3% (on the mass of WLS), reacted at 65 ℃ for 4 h. The structure and performance of the agent was characterized. The results showed that the WLS- 20 had absorbance to UV light, and the maximum absorption wavelength is 195 nm. WLS- 20 additives dosage and absorbance had the best linear relationship under the maximum ab⁃sorption wavelength. WLS- 20 synthesized under the optimum conditions could reduce the white cloth stain⁃ing during soaping, and effectively improved the color fastness to washing and crocking of cotton fabric.%首先以废弃羽毛蛋白和自制反应性阳离子交联改性剂WLS为原料,制备一种季铵型阳离子生物蛋白衍生物固色剂WLS-20,再将其用于活性染料染色棉织物固色后处理中。以皂洗后处理时色布对白布沾色程度(测定K/S值)以及耐皂洗色牢度等为评价指标,研究了废弃羽毛蛋白粉与WLS质量比、碱剂用量、反应温度、反应时间等合成工艺条件对染色棉织物固色效果的影响,确定了固色剂WLS-20的最佳合成条件:羽毛蛋白与WLS质量比为1∶16,氢氧化钠用量为3%(对WLS质量),65℃恒温反应4 h,并对该助剂结构和性能进行了表征。研究结果表明

  11. Titulações potenciométricas de cátions metálicos tendo como eletrodo indicador o sistema Cu/Cu(II-EDTA Potentiometric titrations of metal cations with edta using the Cu/Cu(II-EDTA system as indicator electrode

    Directory of Open Access Journals (Sweden)

    Paulo H. Pereira da Silva

    2008-01-01

    Full Text Available In potentiometric titrations of metal cations with EDTA the Hg/HgY2- system is usually used to detect the end point. However, the use of mercury has been discouraged in analytical procedures due to its toxicity. In this work the Cu/CuY2- system was used as indicator electrode for potentiometric titrations of some metal cations with EDTA. The solutions of Cu2+, Cd2+, Mn2+, Co2+ and Zn2+ were titrated with Na2EDTA solution in the presence of a small concentration of the CuY2- complex using a copper wire as indicator electrode. The potentiometric titrations with the Cu/CuY2- system showed good correlation when compared with an Hg/HgY2- system.

  12. Metal based isatin-derived sulfonamides: their synthesis, characterization, coordination behavior and biological activity.

    Science.gov (United States)

    Chohan, Zahid H; Supuran, Claudiu T; Ben Hadda, Taibi; Nasim, Faiz-Ul-Hassan; Khan, Khalid M

    2009-06-01

    Some isatin derived sulfonamides and their transition metal [Co(II), Cu(II), Ni(II), Zn(II)] complexes have been synthesized and characterized. The structure of synthesized compounds and their nature of bonding have been inferred on the basis of their physical (magnetic susceptibility and conductivity measurements), analytical (elemental analyses) and spectral (IR, (1)H NMR and (13)C NMR) properties. An octahedral geometry has been suggested for Co(II), Ni(II) and Zn(II) and square-planar for Cu(II) complexes. In order to assess the antibacterial and antifungal behavior, the ligands and their metal(II) complexes were screened for their in vitro antibacterial activity against four Gram-negative species, Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa and Salmonella typhi and two Gram-positive species, Staphylococcus aureus and Bacillus subtilis and, for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. In vitro cytotoxic properties of all the compounds were also studied against Artemia salina by brine shrimp bioassay. The results of average antibacterial/antifungal activity showed that zinc(II) complexes were found to be the most active against one or more bacterial/fungal strains as compared to the other metal complexes. PMID:18825557

  13. Chemical and biological metal nanoparticles as antimycobacterial agents: A comparative study.

    Science.gov (United States)

    Singh, Richa; Nawale, Laxman U; Arkile, Manisha; Shedbalkar, Utkarsha U; Wadhwani, Sweety A; Sarkar, Dhiman; Chopade, Balu A

    2015-08-01

    Resistance among mycobacteria leading to multidrug-resistant and extensively drug-resistant tuberculosis is a major threat. However, nanotechnology has provided new insights in drug delivery and medicine development. This is the first comparative report to determine the activity of chemically and biologically synthesised silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) against mycobacteria. Screening data revealed the high mycobactericidal efficiency of AgNPs, with minimum inhibitory concentrations (MICs) of therapeutics for tuberculosis.

  14. SYNTHESIS AND BIOLOGICAL ACTIVITY OF BUTANONE THIOSEMICARBAZONE AND THEIR METALLIC COMPLEXES

    OpenAIRE

    Sandeep Kumar; Nitin Kumar

    2013-01-01

    In present work, Ligand butanone thiosemicarbazone and their 11 complexes of the type ML2X2, ML2X’, where M = Cu(II), Cd(II), Co(II), Zn(II), Hg(II); L = butanone thiosemicarbazone; X = Cl, NO3 or CH3COO; X’ = SO4 have been synthesized and characterized with the help of infra-red and ultra-violet spectroscopy. The spectral data revealed that the thiosemicarbazone act as bidentate ligand, making use of thionic sulphur and the azomethine nitrogen atom for co-ordination to the central metal a...

  15. Integrated chemical/biological treatment of paint stripper mixed waste: Metals toxicity and separation

    International Nuclear Information System (INIS)

    The DOE complex has generated vast quantities of complex heterogeneous mixed wastes. Paint stripper waste (PSW) is a complex waste that arose from decontamination and decommissioning activities. It contains paint stripper, cheesecloth, cellulose-based paints with Pb and Cr, and suspect Pu. Los Alamos National Laboratory has 150--200 barrels of PSW and other national laboratories such as Rocky Flats Plant have many more barrels of heterogeneous waste. Few technologies exist that can treat this complex waste. Our approach to solving this problem is the integration of two established technologies: biodegradation and metals chelation

  16. Structural and biological evaluation of some metal complexes of vanillin-4N-(2-pyridyl) thiosemicarbazone

    Science.gov (United States)

    Yousef, T. A.; Abu El-Reash, G. M.; Al-Jahdali, M.; El-Rakhawy, El-Bastawesy R.

    2013-12-01

    The synthesis and characterization of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and U(VI)O2 complexes of vanillin-4N-(2-pyridyl) thiosemicarbazone (H2PVT) are reported. Theoretical calculations have been performed to obtain IR spectra of ligand and its complexes using AM1, Zindo/1, MM+ and PM3, methods. The Schiff base and its metal complexes have been screened for antibacterial Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus saprophyticus. H2VPT shows no apparent digestion effect on the egg albumin while Mn(II), Hg(II) and Cu(II) complexes exhibited a considerable digestion effect following the order Cu(II) > Mn(II) > Hg(II). Moreover, Ni(II) and Co(II) complexes revealed strong digestion effect. Fe(II), Mn(II), Cu(II), Zn(II) and Ni(II) acted as metal co- SOD enzyme factors, which are located in different compartments of the cell.

  17. Metal complexes of the fourth generation quinolone antimicrobial drug gatifloxacin: Synthesis, structure and biological evaluation

    Science.gov (United States)

    Sadeek, Sadeek A.; El-Shwiniy, Walaa H.

    2010-08-01

    Three metal complexes of the fourth generation quinolone antimicrobial agent gatifloxacin (GFLX) with Y(ΙΙΙ), Zr(ΙV) and U(VΙ) have been prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, gatifloxacin acts as a bidentate deprotonated ligand bound to the metal through the ketone oxygen and a carboxylato oxygen. The complexes are six-coordinated with distorted octahedral geometry. The kinetic parameters for gatifloxacin and the three prepared complexes have been evaluated from TGA curves by using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. The calculated bond length and force constant, F(U dbnd O), for the UO 2 bond in uranyl complex are 1.7522 Å and 639.46 N m -1. The antimicrobial activity of the complexes has been tested against microorganisms, three bacterial species, such as Staphylococcus aureus ( S. aureus), Escherichia coli ( E. coli) and Pseudomonas aeruginosa ( P. aeruginosa) and two fungi species, penicillium ( P. rotatum) and trichoderma ( T. sp.), showing that they exhibit higher activity than free ligand.

  18. Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater

    Science.gov (United States)

    Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.; Küsel, Kirsten

    2016-01-01

    The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems.

  19. Metallic Nanoislands on Graphene as Highly Sensitive Transducers of Mechanical, Biological, and Optical Signals.

    Science.gov (United States)

    Zaretski, Aliaksandr V; Root, Samuel E; Savchenko, Alex; Molokanova, Elena; Printz, Adam D; Jibril, Liban; Arya, Gaurav; Mercola, Mark; Lipomi, Darren J

    2016-02-10

    This article describes an effect based on the wetting transparency of graphene; the morphology of a metallic film (≤20 nm) when deposited on graphene by evaporation depends strongly on the identity of the substrate supporting the graphene. This control permits the formation of a range of geometries, such as tightly packed nanospheres, nanocrystals, and island-like formations with controllable gaps down to 3 nm. These graphene-supported structures can be transferred to any surface and function as ultrasensitive mechanical signal transducers with high sensitivity and range (at least 4 orders of magnitude of strain) for applications in structural health monitoring, electronic skin, measurement of the contractions of cardiomyocytes, and substrates for surface-enhanced Raman scattering (SERS, including on the tips of optical fibers). These composite films can thus be treated as a platform technology for multimodal sensing. Moreover, they are low profile, mechanically robust, semitransparent and have the potential for reproducible manufacturing over large areas. PMID:26765039

  20. SYNTHESIS AND BIOLOGICAL ACTIVITY OF BUTANONE THIOSEMICARBAZONE AND THEIR METALLIC COMPLEXES

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar

    2013-01-01

    Full Text Available In present work, Ligand butanone thiosemicarbazone and their 11 complexes of the type ML2X2, ML2X’, where M = Cu(II, Cd(II, Co(II, Zn(II, Hg(II; L = butanone thiosemicarbazone; X = Cl, NO3 or CH3COO; X’ = SO4 have been synthesized and characterized with the help of infra-red and ultra-violet spectroscopy. The spectral data revealed that the thiosemicarbazone act as bidentate ligand, making use of thionic sulphur and the azomethine nitrogen atom for co-ordination to the central metal atom. All the compounds have been screened for their antibacterial activity against Gram positive bacteria Staphylococcus aureus, Staphylococcus epidermidis and Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. Some of complexes exhibited appreciable activity.

  1. Derivatives of phosphate Schiff base transition metal complexes: synthesis, studies and biological activity

    Science.gov (United States)

    El-Wahab, Z. H. Abd; El-Sarrag, M. R.

    2004-01-01

    We report the synthesis and structural characterization of series of tetra- and hexacoordinate metal chelate complexes of phosphate Schiff base ligands having the general composition LMX n·H 2O and L 2MX n (L=phosphate Schiff base ligand; M=Ag +, Mn 2+, Cu 2+, Zn 2+, Cd 2+, Hg 2+, or Fe 3+ and X=NO 3-, Br - or Cl -). The structure of the prepared compounds was investigated using elemental analysis, IR, 1H and 31P NMR, UV-vis, mass spectra, solid reflectance, magnetic susceptibility and conductance measurements as well as conductometric titration. In all the complexes studied, the ligands act as a chelate ligand with coordination involving the phosphateO-atom and the azomethineN-atom. IR, solid reflectance spectra and magnetic moment measurement are used to infer the structure and to illustrate the coordination capacity of ligand. IR spectra show the presence of coordinated nitrate and water molecule, the magnetic moments of all complexes show normal magnetic behavior and the electronic spectra of the metal complexes indicate a tetra- and octahedral structure for Mn 2+, octahedral structure of Fe 3+ and both square-planar and distorted octahedral structure for Cu 2+ complexes. Antimicrobial activity of the ligands and their complexes were tested using the disc diffusion method and the chosen strains include Staphylococcus aureus, Pseudomonas aereuguinosa, Klebsiella penumoniae, Escherichia coli, Microsporum canis, Trichophyton mentagrophyte and Trichophyton rubrum. Some known antibiotics are included for the sake of comparison and the chosen antibiotic are Amikacin, Doxycllin, Augmantin, Sulperazon, Unasyn, Septrin, Cefobid, Ampicillin, Nitrofurantion, Traivid and Erythromycin.

  2. Scanning electron microscopy at macromolecular resolution in low energy mode on biological specimens coated with ultra thin metal films.

    Science.gov (United States)

    Peters, K R

    1979-01-01

    In this report, conditions for attaining high resolution in scanning electron microscopy with soft biological specimens are described using the currently available high resolution scanning electron microscopes in emission mode of low energy electrons (secondary and charging electrons). Retinal rod outer segments, red blood cells, intestinal mucosa, and ferritin molecules were all used as biological test specimens. From uncoated specimens a new source of signal, referred to as a discharge signal, can provide a high yield of low energy electrons from an excitation area approximately the size of the beam's cross section. Additionally, under these conditions sufficient topographic contrast can be achieved by applying ultra thin metal coatins. A 0.5 nm thick gold film is found sufficient for generating the total signal, whereas increased coating thickness causes additional topographic background signal. However, a 2.0 nm film is needed for imaging surface details with the present instrument. Ultra thin, even, and grainless tantalum films have been found effective in eliminating the charging artifacts caused by external fields, and the decoration artifacts caused by crystal growth as seen in gold films. To improve, in high magnification work on ultra thin coated specimen, signal-to-noise ratio, methods for obtaining saturation of the signal with discharge electrons are shown. The necessity of confirming the information obtained in SEM by independent techniques (TEM of stereo-replicas or ultra thin sections) is discussed. PMID:392703

  3. Selectivity of the highly preorganized tetradentate ligand 2,9-di(pyrid-2-yl)-1,10-phenanthroline for metal ions in aqueous solution, including lanthanide(III) ions and the uranyl(VI) cation.

    Science.gov (United States)

    Carolan, Ashley N; Cockrell, Gregory M; Williams, Neil J; Zhang, Gang; VanDerveer, Donald G; Lee, Hee-Seung; Thummel, Randolph P; Hancock, Robert D

    2013-01-01

    Some metal ion complexing properties of DPP (2,9-Di(pyrid-2-yl)-1,10-phenanthroline) are reported with a variety of Ln(III) (Lanthanide(III)) ions and alkali earth metal ions, as well as the uranyl(VI) cation. The intense π-π* transitions in the absorption spectra of aqueous solutions of 10(-5) M DPP were monitored as a function of pH and metal ion concentration to determine formation constants of the alkali-earth metal ions and Ln(III) (Ln = lanthanide) ions. It was found that log K(1)(DPP) for the Ln(III) ions has a peak at Ln(III) = Sm(III) in a plot of log K(1) versus 1/r(+) (r(+) = ionic radius for 8-coordination). For Ln(III) ions larger than Sm(III), there is a steady rise in log K(1) from La(III) to Sm(III), while for Ln(III) ions smaller than Sm(III), log K(1) decreases slightly to the smallest Ln(III) ion, Lu(III). This pattern of variation of log K(1) with varying size of Ln(III) ion was analyzed using MM (molecular mechanics) and DFT (density functional theory) calculations. Values of strain energy (∑U) were calculated for the [Ln(DPP)(H(2)O)(5)](3+) and [Ln(qpy)(H(2)O)(5)](3+) (qpy = quaterpyrdine) complexes of all the Ln(III) ions. The ideal M-N bond lengths used for the Ln(III) ions were the average of those found in the CSD (Cambridge Structural Database) for the complexes of each of the Ln(III) ions with polypyridyl ligands. Similarly, the ideal M-O bond lengths were those for complexes of the Ln(III) ions with coordinated aqua ligands in the CSD. The MM calculations suggested that in a plot of ∑U versus ideal M-N length, a minimum in ∑U occurred at Pm(III), adjacent in the series to Sm(III). The significance of this result is that (1) MM calculations suggest that a similar metal ion size preference will occur for all polypyridyl-type ligands, including those containing triazine groups, that are being developed as solvent extractants in the separation of Am(III) and Ln(III) ions in the treatment of nuclear waste, and (2) Am(III) is very

  4. Protonation of a hydroxide anion bridging two divalent magnesium cations in water probed by first-principles metadynamics simulation.

    Science.gov (United States)

    Park, Jung Mee; Boero, Mauro

    2010-09-01

    The protonation of a hydroxide anion (OH(-)) located between two magnesium cations (Mg(2+)) in aqueous solution has been investigated by first-principles metadynamics simulation. We observe that the complex Mg(2+)-OH(-)-Mg(2+) is stabilized by the coparticipation of the hydroxide anion to the first hydration shells of both the Mg(2+) cations. Contrary to the cases of OH(-) in pure water, the transfer of protons in the presence of the divalent metal ions turns out to be a slow chemical event. This can be ascribed to the decreased proton affinity of the bridging OH(-). Metadynamics simulation, used to overcome the difficulty of the long time scale required by the protonation of the bridging OH(-), has shown that the system possesses a great stability on the reactant state, characterized by a bioctahedral (6,6) solvation structure around the two Mg(2+) cations. The exploration of the free energy landscape shows that this stable bioctahedral configuration converts into a lower coordinated (5,6) structure, leading to a proton transfer from a water molecule belonging to the first solvation shell of the Mg(2+) ion having the lower coordination to the bridging OH(-); the free energy barrier for the protonation reaction is 11 kcal/mol, meaning that the bridging hydroxide is a weak base. During the proton transfer, the bridging OH(-) reverts to an H(2)O molecule, and this breaks the electrostatic coupling of the two Mg(2+) ions, which depart independently with their own hydration shells, one of which is entirely formed by water molecules. The second one carries the newly created OH(-). Our results show that the flexibility in the metal coordination plays a crucial role in both the protonation process of the bridging OH(-) and the separation of the metal cations, providing useful insight into the nature of proton transfer in binuclear divalent metal ions, with several biological implications, such as, for instance, transesterification of catalytic RNA.

  5. Study of Ion Specific Interactions of Alkali Cations with Dicarboxylate Dianions

    Energy Technology Data Exchange (ETDEWEB)

    Murdachaew, Garold; Valiev, Marat; Kathmann, Shawn M.; Wang, Xue B.

    2012-02-10

    Alkali metal cations often show pronounced ion specific interactions and selectivity with macromolecules in biological processes, colloids, and interfacial sciences, but a fundamental understanding about the underlying microscopic mechanism is still very limited. Here we report a direct probe of interactions between alkali metal cations (M{sup +}) and dicarboxylate dianions, O{sub 2}C(CH{sub 2})nCO{sub 2} (D{sub n}{sup 2-}) in the gas phase by combined photoelectron spectroscopy (PES) and ab initio electronic structure calculation on nine M{sup +}-D{sub n}{sup 2-} complexes (M = Li, Na, K; n = 2, 4, 6). PES spectra show that the electron binding energy (EBE) decreases from Li{sup +} to Na{sup +} to K{sup +} for complexes of M{sup +}-D{sub 2}{sup 2-}, whereas the order is Li{sup +} cation M{sup +}. The observed variance of EBEs reflects how well a specific dicarboxylate dianion accommodates each M{sup +}. This work demonstrates the delicate interplay among several factors (electrostatic interaction, size matching, and strain energy) that likely play critical roles in determining the structures and energetics of gaseous clusters as well as ion specificity and selectivity in solutions and biological systems.

  6. Role of extracellular cations in cell motility, polarity, and chemotaxis

    Directory of Open Access Journals (Sweden)

    Soll D

    2011-04-01

    Full Text Available David R Soll1, Deborah Wessels1, Daniel F Lusche1, Spencer Kuhl1, Amanda Scherer1, Shawna Grimm1,21Monoclonal Antibody Research Institute, Developmental Studies, Hybridoma Bank, Department of Biology, University of Iowa, Iowa City; 2Mercy Medical Center, Surgical Residency Program, Des Moines, Iowa, USAAbstract: The concentration of cations in the aqueous environment of free living organisms and cells within the human body influence motility, shape, and chemotaxis. The role of extracellular cations is usually perceived to be the source for intracellular cations in the process of homeostasis. The role of surface molecules that interact with extracellular cations is believed to be that of channels, transporters, and exchangers. However, the role of Ca2+ as a signal and chemoattractant and the discovery of the Ca2+ receptor have demonstrated that extracellular cations can function as signals at the cell surface, and the plasma membrane molecules they interact with can function as bona fide receptors that activate coupled signal transduction pathways, associated molecules in the plasma membrane, or the cytoskeleton. With this perspective in mind, we have reviewed the cationic composition of aqueous environments of free living cells and cells that move in multicellular organisms, most notably humans, the range of molecules interacting with cations at the cell surface, the concept of a cell surface cation receptor, and the roles extracellular cations and plasma membrane proteins that interact with them play in the regulation of motility, shape, and chemotaxis. Hopefully, the perspective of this review will increase awareness of the roles extracellular cations play and the possibility that many of the plasma membrane proteins that interact with them could also play roles as receptors.Keywords: extracellular cations, chemotaxis, transporters, calcium, receptors

  7. Structural biology of the sequestration and transport of heavy metal toxins: NMR structure determination of proteins containing the -Cys-X-Y-Cys-metal binding motifs. 1997 annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Opella, S.J.

    1997-01-01

    'There are enormous amounts of heavy metals in the environment, much of it in the form of organometallic compounds resulting from various types of industrial and military waste. Nearly all of these metals and compounds are highly toxic to biological organisms including humans. However, some bacteria thrive in the presence of high concentrations of heavy metal toxins because they possess efficient mechanisms for the detoxification of these metals and compounds. Heavy metals appear to be universally toxic because of their non-selective chemistry, for example Hg(II) reacts with essentially all exposed sulfhydryl groups on proteins, thus, it may seem surprising that any organism at all can survive these chemical insults much less those that grow in a toxic milieu. However, the prebiotic environment was undoubtedly heavily polluted with heavy metals from geological processes, and the most primitive organisms simply had to evolve mechanisms for dealing with them if they were going to be able to utilize Cys, His, and the other amino acids that contribute to metal binding sites in their proteins. Genes associated with bacterial resistance to Ag, AsO{sub 2}, AsO{sub 4}, Bi, Cd, Co, CrO{sub 4}, Cu, Hg, iNi, TeO{sub 3}, TI, Pb, Zn, and other metals of environmental concern have been described (Silver, 1992; Silver and Walderhaug, 1995).'

  8. Synthesis, characterization, electrochemical and biological studies on some metal(II) Schiff base complexes containing quinoxaline moiety

    Science.gov (United States)

    Justin Dhanaraj, Chellaian; Johnson, Jijo

    2014-01-01

    Novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base derived from quinoxaline-2,3-(1,4H)-dione and 4-aminoantipyrine (QDAAP) were synthesized. The ligand and its complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., mass and 1H NMR spectral studies. The X band ESR spectrum of the Cu(II) complex at 300 and 77 K were also recorded. Thermal studies of the ligand and its complexes show the presence of coordinated water in the Ni(II) and Zn(II) complexes. The coordination behavior of QDAAP is also discussed. All the complexes are mono nuclear and tetrahedral geometry was found for Co(II) complex. For the Ni(II) and Zn(II) complexes, octahedral geometry was assigned and for the Cu(II) complex, square planar geometry has been suggested. The grain size of the complexes was estimated using powder XRD. The surface morphology of the compounds was studied using SEM analysis. Electrochemical behavior of the synthesized complexes in DMF at room temperature was investigated by cyclic voltammetry. The in vitro biological screening of QDAAP and its metal complexes were tested against bacterial species Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The fungal species include Aspergillus niger, Aspergillus flavus and Candida albicans. The DNA cleavage activity of QDAAP and its complexes were also discussed.

  9. Radiation chemistry of aromatic dimer radical cations

    International Nuclear Information System (INIS)

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  10. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  11. Effect of Synergism and Antagonism between Metals on Toxicity in Soils

    Institute of Scientific and Technical Information of China (English)

    ZHOUDE-ZHI; GUZONG-LIAN; 等

    1991-01-01

    Synergism and antagonism of cadmium(Cd),copper (Cu) and selenium (Se) to biological toxicities in red soil,yellow brown soil and black soil were evaluated by MICROTOX method.The relation between forms of the tested metals in soil and the synergism or antagonism between them was also studied.Results showed that owing to the difference of soil chemical properties,toxicity of these metals in soils was different.In red soil with acid reaction and low in cation exchange capacity,antagonism occurred significantly between metals when they coexisted at high concentrations,while synergism occurred only under low concentrations.It is indicated that in red soil,toxicity of metals affected by synergism or antagonism depends on concentration of the metals present.For yellow brown soil and black soil with larger cation exchange capacity and lower exchangeable aluminium(Al),no toxicity of metals was observed even if metals were added to soil in high concentrations.Synergism and antagonism between Cd,Cu and Se were controlled by the forms of metals present.The amount of water-soluble metals was the most important factor in determining synergism and antagonism. In this paper,comparisons of synergism and antagkonism between metals in soils and in water solutions were made.There occurred the synergism of metal toxicity in water solutions when the concentration of coexisting metals was high.This is just opposite to the case in soils.

  12. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  13. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  14. Metal(loid) levels in biological matrices from human populations exposed to mining contamination--Panasqueira Mine (Portugal).

    Science.gov (United States)

    Coelho, Patrícia; Costa, Solange; Silva, Susana; Walter, Alan; Ranville, James; Sousa, Ana C A; Costa, Carla; Coelho, Marta; García-Lestón, Julia; Pastorinho, M Ramiro; Laffon, Blanca; Pásaro, Eduardo; Harrington, Chris; Taylor, Andrew; Teixeira, João Paulo

    2012-01-01

    Mining activities may affect the health of miners and communities living near mining sites, and these health effects may persist even when the mine is abandoned. During mining processes various toxic wastes are produced and released into the surrounding environment, resulting in contamination of air, drinking water, rivers, plants, and soils. In a geochemical sampling campaign undertaken in the Panasqueira Mine area of central Portugal, an anomalous distribution of several metals and arsenic (As) was identified in various environmental media. Several potentially harmful elements, including As, cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se), were quantified in blood, urine, hair, and nails (toe and finger) from a group of individuals living near the Panasqueira Mine who were environmentally and occupationally exposed. A group with similar demographic characteristics without known exposure to mining activities was also compared. Genotoxicity was evaluated by means of T-cell receptor (TCR) mutation assay, and percentages of different lymphocyte subsets were selected as immunotoxicity biomarkers. Inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis showed elevated levels of As, Cd, Cr, Mn, and Pb in all biological samples taken from populations living close to the mine compared to controls. Genotoxic and immunotoxic differences were also observed. The results provide evidence of an elevated potential risk to the health of populations, with environmental and occupational exposures resulting from mining activities. Further, the results emphasize the need to implement preventive measures, remediation, and rehabilitation plans for the region. PMID:22788375

  15. Low cation coordination in oxide melts

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Lawrie [State University of New York, Stony Brook; Benmore, Chris J [Argonne National Laboratory (ANL); Du, Jincheng [University of North Texas; Weber, Richard [Argonne National Laboratory (ANL); Neuefeind, Joerg C [ORNL; Tumber, Sonia [Materials Development, Inc., Evanston, IL; Parise, John B [Stony Brook University (SUNY)

    2014-01-01

    The complete set of Faber-Ziman partial pair distribution functions for a rare earth oxide liquid were measured for the first time by combining aerodynamic levitation, neutron diffraction, high energy x-ray diffraction and isomorphic substitution using Y2 O3 and Ho2 O3 melts. The average Y- O coordination is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2 O3 (or Ho2 O3 ). Investigation of high temperature La2 O3 , ZrO2 , SiO2 , and Al2 O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation- oxygen coordination. These measurements suggest a general trend towards lower M-O coordination compared to their crystalline counterparts. It is found that this coordination number drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses.

  16. Low Cation Coordination in Oxide Melts

    Science.gov (United States)

    Skinner, L. B.; Benmore, C. J.; Weber, J. K. R.; Du, J.; Neuefeind, J.; Tumber, S. K.; Parise, J. B.

    2014-04-01

    The complete set of partial pair distribution functions for a rare earth oxide liquid are measured by combining aerodynamic levitation, neutron and x-ray diffraction on Y2O3, and Ho2O3 melts at 2870 K. The average Y-O (or Ho-O) coordination of these isomorphic melts is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2O3 (or Ho2O3). Investigation of La2O3, ZrO2, and Al2O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation-oxygen coordination. These measurements suggest a general trend towards lower coordination compared to their crystalline counterparts. It is found that the coordination drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations, such as SiO2. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses.

  17. Ion exchange behaviour of polymeric zirconium cations

    International Nuclear Information System (INIS)

    Polymeric zirconium cations formed in weakly acid solutions (pH2) are taken up strongly into macroporous cation exchange resins, while uptake into normal cation exchange resins (pore diameter about 1 nm) is low. Macroporous cation exchange resins loaded with polymeric Zr cations are shown to function as ligand exchange sorbents. (Authors)

  18. Effect of water coordination on competition between π and non-π cation binding sites in aromatic amino acids: L-phenylalanine, L-tyrosine, and L-tryptophan Li+, Na +, and K+ complexes.

    Science.gov (United States)

    Remko, Milan; Šoralová, Stanislava

    2012-04-01

    Quantum chemistry methods have been applied to charged complexes of the alkali metals Li(+), Na(+), and K(+) with the aromatic amino acids (AAAs) phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp). The geometries of 72 different complexes (Phe·M, Tyr·M, Trp·M, M is Li(+), Na(+), or K(+)) were completely optimized at the B3LYP/6-311+G(d,p) level of density functional theory. The solvent effect on the geometry and stability of individual complexes was studied by making use of a microsolvation model. The interaction enthalpies, entropies, and Gibbs energies of nine different complexes of the systems Phe·M, Tyr·M, and Trp·M (M is Li(+), Na(+), or K(+)) were also determined at the B3LYP density functional level of theory. The calculated Gibbs binding energies of the M(+)-AAA complexes follow the order Phe < Tyr < Trp for all three metal cations studied. Among the three AAAs studied, the indole ring of Trp is the best π donor for alkali metal cations. Our calculations demonstrated the existence of strong cation-π interactions between the alkali metals and the aromatic side chains of the three AAAs. These AAAs comprise about 8% of all known protein sequences. Thus, besides the potential for hydrogen-bond interaction, aromatic residues of Phe, Tyr, and Trp show great potential for π-donor interactions. The existence of cation-π interaction in proteins has also been demonstrated experimentally. However, more complex experimental studies of metal cation-π interaction in diverse biological systems will no doubt lead to more exact validation of these investigations.

  19. A New Sample Substrate for Imaging and Correlating Organic and Trace Metal Composition in Biological Cells and Tissues

    Energy Technology Data Exchange (ETDEWEB)

    Miller,L.; Wang, Q.; Smith, R.; Zhong, H.; Elliott, D.; Warren, J.

    2007-01-01

    Many disease processes involve alterations in the chemical makeup of tissue. Synchrotron-based infrared (IR) and X-ray fluorescence (XRF) microscopes are becoming increasingly popular tools for imaging the organic and trace metal compositions of biological materials, respectively, without the need for extrinsic labels or stains. Fourier transform infrared microspectroscopy (FTIRM) provides chemical information on the organic components of a material at a diffraction-limited spatial resolution of 2-10 {mu}m in the mid-infrared region. The synchrotron X-ray fluorescence (SXRF) microprobe is a complementary technique used to probe trace element content in the same systems with a similar spatial resolution. However to be most beneficial, it is important to combine the results from both imaging techniques on a single sample, which requires precise overlap of the IR and X-ray images. In this work, we have developed a sample substrate containing a gold grid pattern on its surface, which can be imaged with both the IR and X-ray microscopes. The substrate consists of a low trace element glass slide that has a gold grid patterned on its surface, where the major and minor parts of the grid contain 25 and 12 nm gold, respectively. This grid pattern can be imaged with the IR microscope because the reflectivity of gold differs as a function of thickness. The pattern can also be imaged with the SXRF microprobe because the Au fluorescence intensity changes with gold thickness. The tissue sample is placed on top of the patterned substrate. The grid pattern's IR reflectivity image and the gold SXRF image are used as fiducial markers for spatially overlapping the IR and SXRF images from the tissue. Results show that IR and X-ray images can be correlated precisely, with a spatial resolution of less than one pixel (i.e., 2-3 microns). The development of this new tool will be presented along with applications to paraffin-embedded metalloprotein crystals, Alzheimer's disease

  20. Synthesis, characterization and biological activities of metal(II) dipicolinate complexes derived from pyridine-2,6-dicarboxylic acid and 2-(piperazin-1-yl)ethanol

    Science.gov (United States)

    Büyükkıdan, Nurgün; Yenikaya, Cengiz; İlkimen, Halil; Karahan, Ceyda; Darcan, Cihan; Korkmaz, Tülin; Süzen, Yasemin

    2015-12-01

    The new water-soluble and air stable compounds (H2ppz)[Co(dipic)2]·6H2O (1), (H2ppz)[Ni(dipic)2]·6H2O (2) and (H2ppz)[Zn(dipic)2]·6H2O (3) were prepared by the reaction of corresponding metal(II) acetates and a proton transfer salt, (H2ppz) (Hdipic)2, (4) of pyridine-2,6-dicarboxylic acid (H2dipic) and 2-(piperazin-1-yl)ethanol (ppz). The compounds 1-3 were characterized by elemental, IR, UV-vis. thermal analyses, magnetic measurement and single crystal X-ray diffraction studies. The molecular structures of the title compounds consist of one 1-(2-hydroxyethyl)piperazine-1,4-diium (H2ppz+2) cation, one bis(pyridine-2,6-dicarboxylate)metal(II) [M(dipic)2]2- anion, and six uncoordinated water molecules. In compounds 1-3 the metal ions coordinate to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral environment. Antimicrobial activities against Gram (-) wild type (Escherichia coli and Pseudomonas aeruginosa), Gram (+) wild type (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and Bacillus subtilis) and clinical isolate (Morganella morganii, Proteus vulgaris and Enterobacter aeruginosa) were also studied. The results were reported, discussed and compared with the corresponding starting materials ((H2ppz) (Hdipic)2 (4), H2dipic and ppz). MIC (Minimal Inhibition Concentration) values of the newly synthesized compounds were determined as 4000 μg/ml (except B. subtilis and clinical isolate E. aeruginosa, >4000 μg/ml).

  1. Benthic macroalgae as biological indicators of heavy metal pollution in the marine environments: a biomonitoring approach for pollution assessment.

    Science.gov (United States)

    Chakraborty, Sukalyan; Bhattacharya, Tanushree; Singh, Gurmeet; Maity, Jyoti Prakash

    2014-02-01

    Metal pollution in the marine coastline environment is an important topical issue in the context of ecological disturbance and climate change. Heavy metal contaminations (Cd, Cr, Cu, Mn, Ni, Pb and Zn) in seawater and surficial sediments, as well as macroalgal diversity, were determined in six different locations along the coast of the Gulf of Kutch in India. The marine coastline environment was found to be enriched with Cd and Zn in comparison to other metals. Significant (p ≤ 0.05) inter-elemental positive-correlations were observed between Fe-Mn, Fe-Cu, Fe-Cr, Fe-Zn, Cr-Cu, Cu-Mn, and Cd-Zn, as well as negative-correlations between Cd-Pb, Ni-Pb, and Zn-Pb. Though genus specific macroalgal responses to heavy metal accumulation were significant, species specific response was insignificant (p ≤ 0.05). The relative abundance of metals in macroalgae followed the order of Fe>Zn>Mn>Cu>Cd>Cr>Ni>Pb. The high uptake of metals in green algae (Ulva lactuca and Enteromorpha intestinalis) and brown algae (Padina gymnospora and Dictyota bartayresiana) suggested that these algae may be used as potential biomonitors for heavy metal pollution. Three pollution indicators, Contamination Factor (CF), Enrichment Factor (EF) and Geochemical Index (Igeo) were calculated to determine the degree of metal pollution in the marine coastline and the contribution of anthropogenic influence.

  2. Anion binding in biological systems

    Science.gov (United States)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  3. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Feiters, Martin C [Department of Organic Chemistry, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Meyer-Klaucke, Wolfram [EMBL Hamburg Outstation at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kostenko, Alexander V; Soldatov, Alexander V [Faculty of Physics, Southern Federal University, Sorge 5, Rostov-na-Donu, 344090 (Russian Federation); Leblanc, Catherine; Michel, Gurvan; Potin, Philippe [Centre National de la Recherche Scientifique and Universite Pierre et Marie Curie Paris-VI, Station Biologique de Roscoff, Place Georges Teissier, BP 74, F-29682 Roscoff cedex, Bretagne (France); Kuepper, Frithjof C [Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, Scotland (United Kingdom); Hollenstein, Kaspar; Locher, Kaspar P [Institute of Molecular Biology and Biophysics, ETH Zuerich, Schafmattstrasse 20, Zuerich, 8093 (Switzerland); Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R, E-mail: m.feiters@science.ru.n [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2009-11-15

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L{sub 3} (2p{sub 3/2}) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  4. Development of a Model, Metal-reducing Microbial Community for a System Biology Level Assessment of Desulfovibrio vulgaris as part of a Community

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Dwayne; Schadt, Christopher; Miller, Lance; Phelps, Tommy; Brown, S. D.; Arkin, Adam; Hazen, Terry; Drake, Megin; Yang, Z.K.; Podar, Mircea

    2010-05-17

    One of the largest experimental gaps is between the simplicity of pure cultures and the complexity of open environmental systems, particularly in metal-contaminated areas. These microbial communities form ecosystem foundations, drive biogeochemical processes, and are relevant for biotechnology and bioremediation. A model, metal-reducing microbial community was constructed as either syntrophic or competitive to study microbial cell to cell interactions, cell signaling and competition for resources. The microbial community was comprised of the metal-reducing Desulfovibrio vulgaris Hildenborough and Geobacter sulfurreducens PCA. Additionally, Methanococcus maripaludis S2 was added to study complete carbon reduction and maintain a low hydrogen partial pressure for syntrophism to occur. Further, considerable work has been published on D. vulgaris and the D. vulgaris/ Mc. maripaludis co-culture both with and without stress. We are extending this work by conducting the same stress conditions on the model community. Additionally, this comprehensive investigation includes physiological and metabolic analyses as well as specially designed mRNA microarrays with the genes for all three organisms on one slide so as to follow gene expression changes in the various cultivation conditions as well as being comparable to the co- and individual cultures. Further, state-of -the-art comprehensive AMT tag proteomics allows for these comparisons at the protein level for a systems biology assessment of a model, metal-reducing microbial community. Preliminary data revealed that lactate oxidation by D. vulgaris was sufficient to support both G. sulfurreducens and M. maripaludis via the excretion of H2 and acetate. Fumarate was utilized by G. sulfurreducens and reduced to succinate since neither of the other two organisms can reduce fumarate. Methane was quantified, suggesting acetate and H2 concentrations were sufficient for M. maripaludis. Steady state community cultivation will allow for

  5. Altervalent cation-doped MCM-41 supported palladium catalysts and their catalytic properties

    OpenAIRE

    HAIHUI JIANG; LIGANG GAI; YAN TIAN

    2011-01-01

    Metal cation-doped MCM-41 (M-MCM-41, M = Al, Ce, Co, V or Zr) supported Pd catalysts (Pd/M-MCM-41) were prepared by a solution-based reduction method. The catalysts were characterized by X-ray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and further evaluated by selective hydrogenation of para-chloronitrobenzene (p-CNB) in anhydrous ethanol. The metal cation-containing Pd catalysts can efficiently enhanc...

  6. Complexation Between Cationic Diblock Copolymers and Plasmid DNA

    Science.gov (United States)

    Jung, Seyoung; Reineke, Theresa; Lodge, Timothy

    Deoxyribonucleic acids (DNA), as polyanions, can spontaneously bind with polycations to form polyelectrolyte complexes. When the polycation is a diblock copolymer with one cationic block and one uncharged hydrophilic block, the polyelectrolyte complexes formed with plasmid DNA (pDNA) are often colloidally stable, and show great promise in the field of polymeric gene therapy. While the resulting properties (size, stability, and toxicity to biological systems) of the complexes have been studied for numerous cationic diblocks, the fundamentals of the pDNA-diblock binding process have not been extensively investigated. Herein, we report how the cationic block content of a diblock influences the pDNA-diblock interactions. pDNA with 7164 base pairs and poly(2-deoxy-2-methacrylamido glucopyranose)-block-poly(N-(2-aminoethyl) methacrylamide) (PMAG-b-PAEMA) are used as the model pDNA and cationic diblock, respectively. To vary the cationic block content, two PMAG-b-PAEMA copolymers with similar PMAG block lengths but distinct PAEMA block lengths and a PAEMA homopolymer are utilized. We show that the enthalpy change from pDNA-diblock interactions is dependent on the cationic diblock composition, and is closely associated with both the binding strength and the pDNA tertiary structure.

  7. Structural Biology of The sequestration & Transport of Heavy Metal Toxins: NMR Structure Determination of Proteins Containing the CYS-X-Y-Metal Binding Motif

    Energy Technology Data Exchange (ETDEWEB)

    Stanley J. Opella

    2004-03-10

    The support from the Department of Energy enabled us to initiate research on several proteins from the bacterial mercury detoxification system; in particular, we were able to determine the structures of MerP and related metal binding sequences. We have also worked on the membrane transport proteins MerF and MerT.

  8. Trace metal concentrations in Posidonia oceanica of North Corsica (northwestern Mediterranean Sea: use as a biological monitor?

    Directory of Open Access Journals (Sweden)

    Gosselin Marc

    2006-09-01

    Full Text Available Abstract Background Within semi-closed areas like the Mediterranean Sea, anthropic wastes tend to concentrate in the environment. Metals, in particular, are known to persist in the environment and can affect human health due to accumulation in the food chain. The seagrass Posidonia oceanica, widely found in Mediterranean coastal waters, has been chosen as a "sentinel" to quantify the distribution of such pollutants within the marine environment. Using a technique similar to dendrochronology in trees, it can act as an indicator of pollutant levels over a timeframe of several months to years. In the present study, we measured and compared the levels of eight trace metals (Cr, Ni, Cu, Zn, As, Se, Cd, and Pb in sheaths dated by lepidochronology and in leaves of shoots sampled from P. oceanica meadows collected from six offshore sites in northern Corsica between 1988 and 2004; in the aim to determine 1 the spatial and 2 temporal variations of these metals in these areas and 3 to compared these two types of tissues. Results We found low trace metal concentrations with no increase over the last decade, confirming the potential use of Corsican seagrass beds as reference sites for the Mediterranean Sea. Temporal trends of trace metal concentrations in sheaths were not significant for Cr, Ni, Cu, As or Se, but Zn, Cd, and Pb levels decreased, probably due to the reduced anthropic use of these metals. Similar temporal trends between Cu levels in leaves (living tissue and in sheaths (dead tissue demonstrated that lepidochronology linked with Cu monitoring is effective for surveying the temporal variability of this metal. Conclusion Leaves of P. oceanica can give an indication of the metal concentration in the environment over a short time period (months with good accuracy. On the contrary, sheaths, which gave an indication of changes over long time periods (decades, seem to be less sensitive to variations in the metal concentration in the environment

  9. The Biological Effects of Combining Metals in a Posterior Spinal Implant: In Vivo Model Development Report of the First Two Cases

    Directory of Open Access Journals (Sweden)

    Christine L. Farnsworth

    2014-01-01

    Full Text Available Study Design. Combinations of metal implants (stainless steel (SS, titanium (Ti, and cobalt chrome (CC were placed in porcine spines. After 12 months, tissue response and implant corrosion were compared between mixed and single metal junctions. Objective. Model development and an attempt to determine any detriment of combining different metals in posterior spinal instrumentation. Methods. Yucatan mini-pigs underwent instrumentation over five unfused lumbar levels. A SS rod and a Ti rod were secured with Ti and SS pedicle screws, SS and Ti crosslinks, SS and CC sublaminar wires, and Ti sublaminar cable. The resulting 4 SS/SS, 3 Ti/Ti, and 11 connections between dissimilar metals per animal were studied after 12 months using radiographs, gross observation, and histology (foreign body reaction (FBR, metal particle count, and inflammation analyzed. Results. Two animals had constructs in place for 12 months with no complications. Histology of tissue over SS/SS connections demonstrated 11.1 ± 7.6 FBR cells, 2.1 ± 1.7 metal particles, and moderate to extensive inflammation. Ti/Ti tissue showed 6.3 ± 3.8 FBR cells, 5.2 ± 6.7 particles, and no to extensive inflammation (83% extensive. Tissue over mixed components had 14.1 ± 12.6 FBR cells and 13.4 ± 27.8 particles. Samples surrounding wires/cables versus other combinations demonstrated FBR (12.4 ± 13.5 versus 12.0 ± 9.6 cells, P = 0.96, particles (19.8 ± 32.6 versus 4.3 ± 12.7, P = 0.24, and inflammation (50% versus 75% extensive, P = 0.12. Conclusions. A nonfusion model was developed to study corrosion and analyze biological responses. Although no statistical differences were found in overlying tissue response to single versus mixed metal combinations, galvanic corrosion between differing metals is not ruled out. This pilot study supports further investigation to answer concerns when mixing metals in spinal constructs.

  10. Synthesis, Spectral Characterization, and Biological Evaluation of Transition Metal Complexes of Bidentate N, O Donor Schiff Bases

    Directory of Open Access Journals (Sweden)

    Sajjad Hussain Sumrra

    2014-01-01

    Full Text Available New series of three bidentate N, O donor type Schiff bases (L1–(L3 were prepared by using ethylene-1,2-diamine with 5-methyl furfural, 2-anisaldehyde, and 2-hydroxybenzaldehyde in an equimolar ratio. These ligands were further complexed with Co(II, Cu(II, Ni(II, and Zn(II metals to produce their new metal complexes having an octahedral geometry. These compounds were characterized on the basis of their physical, spectral, and analytical data. Elemental analysis and spectral data of the uncomplexed ligands and their metal(II complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. All ligands and their metal complexes were screened for antimicrobial activity. The results of antimicrobial activity indicated that metal complexes have significantly higher activity than corresponding ligands. This higher activity might be due to chelation process which reduces the polarity of metal ion by coordinating with ligands.

  11. Heavy Metals Affect Nematocysts Discharge Response and Biological Activity of Crude Venom in the Jellyfish Pelagia noctiluca (Cnidaria, Scyphozoa

    Directory of Open Access Journals (Sweden)

    Rossana Morabito

    2014-07-01

    Full Text Available Background: Pollution of marine ecosystems and, specifically, heavy metals contamination may compromise the physiology of marine animals with events occurring on a cellular and molecular level. The present study focuses on the effect of short-term exposure to heavy metals like Zinc, Cadmium, Cobalt and Lanthanum (2-10 mM on the homeostasis of Pelagia noctiluca (Cnidaria, Scyphozoa, a jellyfish abundant in the Mediterranean sea. This species possesses stinging organoids, termed nematocysts, whose discharge and concomitant delivery of venom underlie the survival of all Cnidaria. Methods: Nematocysts discharge response, elicited by combined chemico-physical stimulation, was verified on excised oral arms exposed to heavy metals for 20 min. In addition, the hemolytic activity of toxins, contained in the crude venom extracted from nematocysts isolated from oral arms, was tested on human erythrocytes, in the presence of heavy metals or their mixture. Results: Treatment with heavy metals significantly inhibited both nematocysts discharge response and hemolytic activity of crude venom, in a dose-dependent manner, not involving oxidative events, that was irreversible in the case of Lanthanum. Conclusion: Our findings show that the homeostasis of Pelagia noctiluca, in terms of nematocysts discharge capability and effectiveness of venom toxins, is dramatically and rapidly compromised by heavy metals and confirm that this jellyfish is eligible as a model for ecotoxicological investigations.

  12. Cationically polymerizable monomers derived from renewable sources. Annual performance report

    Energy Technology Data Exchange (ETDEWEB)

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year`s research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  13. Potentiometric studies on the complexation equilibria between some trivalent lanthanide metal ions and biologically active 2-hydroxy-1-naphthaldehyde thiosemicarbazone (HNATS)

    International Nuclear Information System (INIS)

    The chelation behaviour of some trivalent lanthanide and yttrium metal ions with biologically active 2-hydroxy-1-naphthaldehyde thiosemicarbazone (HNATS) has been investigated by potentiometric measurements at 20±0.5 deg C in 75% (v/v)dioxane-water medium at various ionic strenghts of sodium perchlorate. The method of Bjerrum and Calvin, as modified by Irving and Rossotti has been used to find out the values of n-bar (average number of ligand bound per metal ion) and pL (free ligand exponent). The formation constants of metal chelates have been computed on a PC-XT computer, using a program patterned after that of Sullivan et al. to give βn values using the weighted least-squares method. The Smin values (Smin=χ2) have been calculated. The order of formation constants of chelates was found to be: La3+3+3+3+3+3+3+3+3+3+. The formation constants of the chelates formed have been correlated to size and ionization potentials of the metal ions. (authors)

  14. Exploring the strength, mode, dynamics, and kinetics of binding interaction of a cationic biological photosensitizer with DNA: implication on dissociation of the drug-DNA complex via detergent sequestration.

    Science.gov (United States)

    Paul, Bijan Kumar; Guchhait, Nikhil

    2011-10-20

    The present study aims at exploring a detailed characterization of the binding interaction of a promising cancer cell photosensitizer, harmane (HM), with DNA extracted from herring sperm. The polarity-sensitive prototropic transformation of HM, a naturally occurring, fluorescent, drug-binding alkaloid, β-carboline, is remarkably modified upon interaction with DNA and is manifested through significant modulations on the absorption and emission profiles of HM. From the series of studies undertaken in the present program, for example, absorption; steady-state emission; the effect of chaotrope (urea); iodide ion-induced steady-state fluorescence quenching; circular dichroism (CD); and helix melting from absorption spectroscopy; the mode of binding of HM into the DNA helix has been substantiated to be principally intercalative. Concomitantly, a discernible dependence of the photophysics of the DNA-bound drug on the medium ionic strength indicates that electrostatic attraction should not be ignored in the interaction. Efforts have also been delivered to delineate the dynamical aspects of the interaction, such as modulation in time-resolved fluorescence decay and rotational relaxation dynamics of the drug within the DNA environment. In view of the prospective biological applications of HM, the issue of facile dissociation of intercalated HM from the DNA helix also comprises a crucial prerequisite for the functioning as an effective therapeutic agent. In this context, our results imply that the concept of detergent-sequestered dissociation of the drug from the drug-DNA complex can be a prospective strategy through an appropriate choice of the detergent molecule. The utility of the present work resides in exploring the potential applicability of the fluorescence property of HM for studying its interactions with a relevant biological target, for example, DNA. In addition, the methods and techniques used in the present work can also be exploited to study the interaction of

  15. Biological indication of heavy metal pollution in the areas of Donje Vlase and Cerje (southeastern Serbia using epiphytic lichens

    Directory of Open Access Journals (Sweden)

    Stamenković S.S.

    2013-01-01

    Full Text Available The performance of two epiphytic lichen species (Evernia prunastri (L. Ach. and Parmelia sulcata Taylor as bioindicators of heavy metal pollution in natural areas around the city of Niš (southeastern Serbia were evaluated. The concentration of 19 heavy metals in lichen samples was measured by inductively coupled plasma-optical emission spectroscopy. For the majority of the elements the concentrations found in Parmelia sulcata Taylor were higher than in Evernia prunastri (L. Ach. In addition, interspecific differences in heavy metal accumulation between Evernia prunastri (L. Ach. and Parmelia sulcata Taylor are observed. Parmelia sulcata Taylor showed a tendency to accumulate Fe, Mn, Ni and Ti while Evernia prunastri (L. Ach. preferentially concentrated Cu on both locations. A clear distinction between lithogenic (Mn-Cu-Ti and atmospheric elements (Ni-Co-Cr-Ag-Pb-Hg was achieved by cluster analysis. [Projekat Ministarstva nauke Republike Srbije, br. III41018, br. OI 171025, br. 172017 and br. III41017

  16. Photodissociation of Cerium Oxide Nanocluster Cations.

    Science.gov (United States)

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)). PMID:27035210

  17. Cationic sulfonium functionalization renders Znsalens with high fluorescence, good water solubility and tunable cell-permeability.

    Science.gov (United States)

    Tang, Juan; Xie, Da; Yin, Hao-Yan; Jing, Jing; Zhang, Jun-Long

    2016-04-01

    In this study, we report for the first time that incorporation of cationic sulfonium to the Znsalens skeleton achieves water soluble fluorescent metal complex probes for living cell imaging. To circumvent Znsalen aggregation arising from intermolecular ZnO interactions (found between Zn and the phenoxyl group of another Znsalen molecule), we synthesized a series of sulfonium Znsalens based on alkylation of the 3-thioether or 3,5-dithioether moieties of salicylaldehydes. Such functionalization not only provides positive charge(s) to enhance electrostatic repulsion, but also increases steric hindrance, which renders the Znsalen complex water soluble as a monomeric species in aqueous media as revealed by diffusion ordered NMR spectroscopy (DOSY). More interestingly, these sulfonium Znsalens display "switched on" fluorescence when compared to thioether analogues, which was attributed to the electron-withdrawing sulfonium moiety that perturbs the photoinduced electron transfer (PET) process as suggested by computational calculations based on time-dependent density functional theory (TD-DFT). Most interestingly, live cell imaging experiments showed that modulation of the sulfonium moieties, such as the number or alkyl substituents, significantly tunes the cell-permeability of the fluorescent Znsalens. Thus, this study has demonstrated the importance of sulfonium functionalization on dissociating the intermolecular metal-ligand interactions and thus, modulating water solubility, photophysical properties and even cell-permeability of the fluorophores, which provides a new approach to the design of functional metal complexes for biological studies. PMID:26883310

  18. A Thermodynamic Model of Monovalent Cation Homeostasis in the Yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Gerber, Susanne; Fröhlich, Martina; Lichtenberg-Fraté, Hella; Shabala, Sergey; Shabala, Lana; Klipp, Edda

    2016-01-01

    Cationic and heavy metal toxicity is involved in a substantial number of diseases in mammals and crop plants. Therefore, the understanding of tightly regulated transporter activities, as well as conceiving the interplay of regulatory mechanisms, is of substantial interest. A generalized thermodynamic description is developed for the complex interplay of the plasma membrane ion transporters, membrane potential and the consumption of energy for maintaining and restoring specific intracellular cation concentrations. This concept is applied to the homeostasis of cation concentrations in the yeast cells of S. cerevisiae. The thermodynamic approach allows to model passive ion fluxes driven by the electrochemical potential differences, but also primary or secondary active transport processes driven by the inter- play of different ions (symport, antiport) or by ATP consumption (ATPases). The model-confronted with experimental data-reproduces the experimentally observed potassium and proton fluxes induced by the external stimuli KCl and glucose. The estimated phenomenological constants combine kinetic parameters and transport coefficients. These are in good agreement with the biological understanding of the transporters thus providing a better understanding of the control exerted by the coupled fluxes. The model predicts the flux of additional ion species, like e.g. chloride, as a potential candidate for counterbalancing positive charges. Furthermore, the effect of a second KCl stimulus is simulated, predicting a reduced cellular response for cells that were first exposed to a high KCl stimulus compared to cells pretreated with a mild KCl stimulus. By describing the generalized forces that are responsible for a given flow, the model provides information and suggestions for new experiments. Furthermore, it can be extended to other systems such as e.g. Candida albicans, or selected plant cells.

  19. A Thermodynamic Model of Monovalent Cation Homeostasis in the Yeast Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Susanne Gerber

    2016-01-01

    Full Text Available Cationic and heavy metal toxicity is involved in a substantial number of diseases in mammals and crop plants. Therefore, the understanding of tightly regulated transporter activities, as well as conceiving the interplay of regulatory mechanisms, is of substantial interest. A generalized thermodynamic description is developed for the complex interplay of the plasma membrane ion transporters, membrane potential and the consumption of energy for maintaining and restoring specific intracellular cation concentrations. This concept is applied to the homeostasis of cation concentrations in the yeast cells of S. cerevisiae. The thermodynamic approach allows to model passive ion fluxes driven by the electrochemical potential differences, but also primary or secondary active transport processes driven by the inter- play of different ions (symport, antiport or by ATP consumption (ATPases. The model-confronted with experimental data-reproduces the experimentally observed potassium and proton fluxes induced by the external stimuli KCl and glucose. The estimated phenomenological constants combine kinetic parameters and transport coefficients. These are in good agreement with the biological understanding of the transporters thus providing a better understanding of the control exerted by the coupled fluxes. The model predicts the flux of additional ion species, like e.g. chloride, as a potential candidate for counterbalancing positive charges. Furthermore, the effect of a second KCl stimulus is simulated, predicting a reduced cellular response for cells that were first exposed to a high KCl stimulus compared to cells pretreated with a mild KCl stimulus. By describing the generalized forces that are responsible for a given flow, the model provides information and suggestions for new experiments. Furthermore, it can be extended to other systems such as e.g. Candida albicans, or selected plant cells.

  20. Patterns of metal composition and biological condition and their association in male common carp across an environmental contaminant gradient in Lake Mead National Recreation Area, Nevada and Arizona, USA.

    Science.gov (United States)

    Patiño, Reynaldo; Rosen, Michael R; Orsak, Erik L; Goodbred, Steven L; May, Thomas W; Alvarez, David; Echols, Kathy R; Wieser, Carla M; Ruessler, Shane; Torres, Leticia

    2012-02-01

    There is a contaminant gradient in Lake Mead National Recreation Area (LMNRA) that is partly driven by municipal and industrial runoff and wastewater inputs via Las Vegas Wash (LVW). Adult male common carp (Cyprinus carpio; 10 fish/site) were collected from LVW, Las Vegas Bay (receiving LVW flow), Overton Arm (OA, upstream reference), and Willow Beach (WB, downstream) in March 2008. Discriminant function analysis was used to describe differences in metal concentrations and biological condition of fish collected from the four study sites, and canonical correlation analysis was used to evaluate the association between metal and biological traits. Metal concentrations were determined in whole-body extracts. Of 63 metals screened, those initially used in the statistical analysis were Ag, As, Ba, Cd, Co, Fe, Hg, Pb, Se, Zn. Biological variables analyzed included total length (TL), Fulton's condition factor, gonadosomatic index (GSI), hematocrit (Hct), and plasma estradiol-17β and 11-ketotestosterone (11kt) concentrations. Analysis of metal composition and biological condition both yielded strong discrimination of fish by site (respective canonical model, p<0.0001). Compared to OA, pairwise Mahalanobis distances between group means were WBmetal concentrations and LVBbiological traits. Respective primary drivers for these separations were Ag, As, Ba, Hg, Pb, Se and Zn; and TL, GSI, 11kt, and Hct. Canonical correlation analysis using the latter variable sets showed they are significantly associated (p<0.0003); with As, Ba, Hg, and Zn, and TL, 11kt, and Hct being the primary contributors to the association. In conclusion, male carp collected along a contaminant gradient in LMNRA have distinct, collection site-dependent metal and morpho-physiological profiles that are significantly associated with each other. These associations suggest that fish health and reproductive condition (as measured by the biological variables evaluated in this study) are

  1. Cationic speciation in nonaqueous media

    International Nuclear Information System (INIS)

    Electronic spectra of solutions of d transition elements in the superacids HF, H2SO4, HSO3F, and CF3SO3H and in chloroaluminate melts indicate that in acidic monaqueous media the elements are present as solvated cations, whereas in basic media the speciation is anionic, the same situation as in aqueous solutions. Further, in very highly acidic media, cations in very low oxidation states are stable (e.g., Ti2+), but these disproportionate on addition of base to the system. In this paper spectra, where available, of U, Np, and Pu in oxidation states III and IV in aqueous media, in protonic superacids, and in chloroaluminates are presented to postulate cationic speciation of these early actinides in highly acidic media

  2. Synthesis, spectral characterisation, morphology, biological activity and DNA cleavage studies of metal complexes with chromone Schiff base

    Directory of Open Access Journals (Sweden)

    P. Kavitha

    2016-07-01

    Full Text Available Cu(II, Co(II, Ni(II and Zn(II complexes have been synthesized using 3-((pyridine-2-yliminomethyl-4H-chromen-4-one as a ligand derived from 3-formyl chromone and 2-amino pyridine. All the complexes were characterised by analytical, conductivity, IR, electronic, magnetic, ESR, thermal, powder XRD and SEM studies. The analytical data revealed that the metal to ligand molar ratio is 1:2 in all the complexes. Molar conductivity data indicates that all the complexes are neutral in nature. On the basis of magnetic and electronic spectral data, octahedral geometry is proposed for all the complexes. Thermal behaviour of the synthesized complexes indicates the coordinated and lattice water molecules are present in the complexes. The X-ray diffraction data suggest a triclinic system for all compounds. Different surface morphologies were identified from SEM micrographs. All metal complexes exhibit fluorescence. The antimicrobial and nematicidal activity data show that metal complexes are more potent than the parent ligand. The DNA cleavage activity of the ligand and its metal complexes were observed in the presence of H2O2.

  3. Biologically active and thermally stable polymeric Schiff base and its metal polychelates: Their synthesis and spectral aspects

    Science.gov (United States)

    Rasool, Raza; Hasnain, Sumaiya

    2015-09-01

    New metal polychelates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) obtained by the interaction of metal acetates with polymeric Schiff base containing formaldehyde and piperazine, have been investigated. Structural and spectroscopic properties have been evaluated by elemental analysis, FT-IR and 1H-NMR. Geometry of the chelated polymers was confirmed by magnetic susceptibility measurements, UV-Visible spectroscopy and Electron Spin Resonance. The molecular weight of the polymer was determined by gel permeation chromatography (GPC). Thermogravimetric analysis indicated that metal polychelates were more thermally stable than their corresponding ligand. All compounds were screened for their antimicrobial activities against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, (bacteria) and Candida albicans, Microsporum canis, Cryptococcus neoformans (fungi) by agar well diffusion method. Interestingly, the polymeric Schiff base was found to be antimicrobial in nature but less effective as compared to the metal polychelates. On the basis of thermal and antimicrobial behavior, these polymers hold potential applications as thermally resistant antimicrobial and antifouling coating materials as well as antimicrobial packaging materials.

  4. Versatile cation transport in imidazolium based polymerized ionic liquids

    Science.gov (United States)

    Evans, Christopher; Segalman, Rachel

    Polymerized ionic liquids (PIL) with tethered imidazolium groups are able to conduct a diverse array of cations relevant for energy applications. The well-known complexation of imidazolium with transition metals is exploited to bind ions such as H +, Li+, Cu2+, and Ni2+ by doping the neutral PIL with the appropriate Cation-TFSI- salt. Conductivities were first determined via AC impedance indicating that H+ salts lead to the highest conductivity (due to low ion mass and potential Grotthus mechanism) followed by Cu2+, Li+, Ag+, and Ni2+. The equilibrium constant for imidazolium complexation is larger for Cu2+ relative to Li-, Ag-, and Ni-imidazolium complexes leading to greater salt dissociation and higher conductivities. For LiTFSI and CuTFSI2 salts, metallic lithium or copper electrodes were employed in battery cells to pass a steady DC current and confirm that the cations are in fact carrying current. Interestingly, the divalent Cu2+ also ionically crosslinks the polymer leading to a plateau in the viscosity. Thus, divalent ions provide an unique route to high conductivity, high modulus polymeric electrolytes. Future studies involving ZnTFSI2 and MgTFSI2 for battery applications are proposed to examine how versatile the PIL platform is for cation transport.

  5. Novel quaternary ammonium hydroxide cationic surfactants as corrosion inhibitors for carbon steel and as biocides for sulfate reducing bacteria (SRB)

    International Nuclear Information System (INIS)

    A series of alkyl dimethylisopropylammonium hydroxide cationic surfactants (DEDIAOH, DODIAOH and HEDIAOH) was synthesized and characterized. The surface properties such as the critical micelle concentration (CMC), the effectiveness of surface tension reduction (ΠCMC), surface excess concentration (Γmax) and surface area per molecule (Amin) have been determined by means of surface tension measurements. The degree of counter ion dissociation (β) and the free energy of micellization (ΔGmic) were calculated. The corrosion inhibition of the synthesized cationic surfactants on carbon steel surface in 1 M HCl solution was investigated. For this purpose, a series of techniques such as gravimetric measurement, potentiodynamic polarization and scanning electron microscope (SEM) were used. The values of activation energy for carbon steel corrosion and the thermodynamic parameters such as adsorption equilibrium constant (Kads), free energy of adsorption (ΔGadso), adsorption heat (ΔHadso) and adsorption entropy (ΔSadso) values were evaluated. Results showed that HEDIAOH had better inhibition effect than DEDIAOH and DODIAOH of the corrosion of carbon steel in 1 M HCl solution and inhibition efficiency is higher than 96% after 24 h at 1 x 10-2 M concentration of the inhibitor. The inhibition efficiency is discussed in terms of strong adsorption of the inhibitor molecules on the metal surface and formation of a protective film. Scanning electron microscope (SEM) showed a good surface coverage on the metal surface. The Biological activity was examined against sulfate reducing bacteria (SRB) by dilution method.

  6. Metal based biologically active compounds: design, synthesis, and antibacterial/antifungal/cytotoxic properties of triazole-derived Schiff bases and their oxovanadium(IV) complexes.

    Science.gov (United States)

    Chohan, Zahid H; Sumrra, Sajjad H; Youssoufi, Moulay H; Hadda, Taibi B

    2010-07-01

    A new series of oxovanadium(IV) complexes have been designed and synthesized with a new class of triazole Schiff bases derived from the reaction of 3,5-diamino-1,2,4-triazole with 2-hydroxy-1-naphthaldehyde, pyrrole-2-carboxaldehyde, pyridine-2-carboxaldehyde and acetyl pyridine-2-carboxaldehyde, respectively. Physical (magnetic susceptibility, molar conductance), spectral (IR, (1)H NMR, (13)C NMR, mass and electronic) and analytical data have established the structures of these synthesized Schiff bases and their oxovanadium(IV) complexes. The Schiff bases, predominantly act as bidentate and coordinate with the vanadium(IV) metal to give a stoichiometric ratio of 1:2 [M:L], forming a general formulae, [M(L-H)(2)] and [M(L)(2)]SO(4) where L = (L(1))-(L(4)) and M = VO(IV) of these complexes in a square-pyramidal geometry. In order to evaluate the biological activity of Schiff bases and to assess the role of vanadium(IV) metal on biological activity, the triazole Schiff bases and their oxovanadium(IV) complexes have been studied for in vitro antibacterial activity against four Gram-negative (Escherichia coli, Shigella flexenari, Pseudomonas aeruginosa, Salmonella typhi) and two Gram-positive (Staphylococcus aureus, Bacillus subtilis) bacterial strains, in vitro antifungal activity against Trichophyton longifucus, Candida albican, Aspergillus flavus, Microscopum canis, Fusarium solani and Candida glaberata. The simple Schiff bases showed weaker to significant activity against one or more bacterial and fungal strains. In most of the cases higher activity was exhibited upon coordination with vanadium(IV) metal. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina. PMID:20338672

  7. Biofilm establishment and heavy metal removal capacity of an indigenous mining algal-microbial consortium in a photo-rotating biological contactor.

    Science.gov (United States)

    Orandi, S; Lewis, D M; Moheimani, N R

    2012-09-01

    An indigenous mining algal-microbial consortium was immobilised within a laboratory-scale photo-rotating biological contactor (PRBC) that was used to investigate the potential for heavy metal removal from acid mine drainage (AMD). The microbial consortium, dominated by Ulothrix sp., was collected from the AMD at the Sar Cheshmeh copper mine in Iran. This paper discusses the parameters required to establish an algal-microbial biofilm used for heavy metal removal, including nutrient requirements and rotational speed. The PRBC was tested using synthesised AMD with the multi-ion and acidic composition of wastewater (containing 18 elements, and with a pH of 3.5 ± 0.5), from which the microbial consortium was collected. The biofilm was successfully developed on the PRBC's disc consortium over 60 days of batch-mode operation. The PRBC was then run continuously with a 24 h hydraulic residence time (HRT) over a ten-week period. Water analysis, performed on a weekly basis, demonstrated the ability of the algal-microbial biofilm to remove 20-50 % of the various metals in the order Cu > Ni > Mn > Zn > Sb > Se > Co > Al. These results clearly indicate the significant potential for indigenous AMD microorganisms to be exploited within a PRBC for AMD treatment.

  8. The influence of bacterial-humus preparations on the biological activity of soils polluted with oil products and heavy metals

    Science.gov (United States)

    Kozlova, E. N.; Stepanov, A. L.; Lysak, L. V.

    2015-04-01

    The influence of bacterial-humus preparations based on Gumigel ( Agrosintez Company) on the biological activity of soddy-podzolic soil polluted with Pb(CH3COO)2 and gasoline was studied in a model experiment. Some indicators of biological activity are shown to depend on soil pollution to different extents. The process of nitrogen fixation and the activity of dehydrogenase and phosphatase were mostly inhibited by Pb(CH3COO)2 and gasoline. Gasoline compared to Pb(CH3COO)2 inhibited the soil biological activity to a greater extent. The bacterial-humus preparations exerted a significant positive effect on the biological activity of the polluted soils manifested in the increase of the total number of bacteria and of the enzyme activity (1.5-5.0 times), in the intensification of nitrogen fixation and denitrification (3-8 times), as well as in the increase in the biomass of the plants grown (1.5-2.0 times). The application of bacterial suspensions of pure cultures or the microbial complex without the preparations of humic acids did not always give a positive effect.

  9. Synthesis, Characterization and Biological Activity of Transition Metals with Schiff Base Derived from Adamantaneamine and o-Vanillin

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Five new solid complexes were synthesized about transition metals with Schiff base(L,C18H23NO2) derived from adamantaneamine and o-vanillin, and characterized by elemental analysis, molar conductance, infrared spectra, UV-vis spectra, thermal analysis. Their chemical formula are [ML2](ClO4)2 (M= Mn,Co,Ni,Cu,Zn),and the coordination numbers are four. The antibacterial activity of Schiff base ligand and its complexes was studied.

  10. Design strategies to improve the sensitivity of photoactive metal carbonyl complexes (photoCORMs) to visible light and their potential as CO-donors to biological targets.

    Science.gov (United States)

    Chakraborty, Indranil; Carrington, Samantha J; Mascharak, Pradip K

    2014-08-19

    The recent surprising discovery of the beneficial effects of carbon monoxide (CO) in mammalian physiology has drawn attention toward site-specific delivery of CO to biological targets. To avoid difficulties in handling of this noxious gas in hospital settings, researchers have focused their attention on metal carbonyl complexes as CO-releasing molecules (CORMs). Because further control of such CO delivery through light-triggering can be achieved with photoactive metal carbonyl complexes (photoCORMs), we and other groups have attempted to isolate such complexes in the past few years. Typical metal carbonyl complexes release CO when exposed to UV light, a fact that often deters their use in biological systems. From the very beginning, our effort therefore was directed toward identifying design principles that could lead to photoCORMs that release CO upon illumination with low-power (5-15 mW/cm(2)) visible and near-IR light. In our work, we have utilized Mn(I), Re(I), and Ru(II) centers (all d(6) ground state configuration) to ensure overall stability of the carbonyl complexes. We also hypothesized that transfer of electron density from the electron-rich metal centers to π* MOs of the ligand frame via strong metal-to-ligand charge transfer (MLCT) transitions in the visible/near-IR region would weaken metal-CO back-bonding and promote rapid CO photorelease. This expectation has been realized in a series of carbonyl complexes derived from a variety of designed ligands and smart choice of ligand/coligand combinations. Several principles have emerged from our systematic approach to the design of principal ligands and the choice of auxiliary ligands (in addition to the number of CO) in synthesizing these photoCORMs. In each case, density functional theory (DFT) and time-dependent DFT (TDDFT) study afforded insight into the dependence of the CO photorelease from a particular photoCORM on the wavelength of light. Results of these theoretical studies indicate that extended

  11. Effects of aluminum and other cations on the structure of brain and liver chromatin.

    Science.gov (United States)

    Walker, P R; LeBlanc, J; Sikorska, M

    1989-05-01

    The reactivity of aluminum and several other divalent and trivalent metallic cations toward chromatin from rat brain and liver has been investigated. Two criteria are used to determine the relative reactivity of these cations toward chromatin. The first involves the ability of the ions to compact the chromatin fibers to the point where chromatin precipitates. The second criterion measures the ability of cations to interfere with the accessibility of exogenous structural probes (nucleases) to chromatin. Of the divalent cations tested, nickel, cobalt, zinc, cadmium, and mercury were the most reactive toward chromatin, on the basis of their ability to induce precipitation of chromatin in the micromolar concentration range. The divalent cations magnesium, calcium, copper, strontium, and barium were much less effective, although all cations precipitate chromatin if their concentration is increased. Of the trivalent cations tested, aluminum, indium, and gallium were very effective precipitants, whereas iron and scandium were without effect at the concentrations tested. Of all the cations tested, aluminum was the most reactive. Aluminum's ability to alter the structure of chromatin was investigated further by testing its ability to interfere with nuclease accessibility. This test confirmed that aluminum does induce considerable changes in chromatin structure at micromolar concentrations. Furthermore, chromatin from cortical areas of the brain was much more sensitive to aluminum than chromatin from liver. These results are discussed in light of the known toxicity of these cations, with particular emphasis on the possible role of aluminum in Alzheimer's disease. PMID:2752000

  12. A preorganized metalloreceptor for alkaline earth ions showing calcium versus magnesium selectivity in water: biological activity of selected metal complexes.

    Science.gov (United States)

    Amatori, Stefano; Ambrosi, Gianluca; Fanelli, Mirco; Formica, Mauro; Fusi, Vieri; Giorgi, Luca; Macedi, Eleonora; Micheloni, Mauro; Paoli, Paola; Rossi, Patrizia

    2014-08-25

    The N,N'-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,N'-dimethylethylendiamine (Malten = L) forms the highly stable [CuH(-2)L] species in water, in which the converging maltol oxygen atoms form an electron-rich area able to host hard metal ions. When considering the alkaline earth series (AE), the [Cu(H(-2)L)] species binds all metal ions, with the exception of Mg(2+), exhibiting the relevant property to discriminate Ca(2+) versus Mg(2+) at physiological pH 7.4; the binding of the AE metal is visible to the naked eye. The stability constant values of the trinuclear [AE{Cu(H(-2)L)}2](2+) species formed reach the maximum for Ca(2+) (log K=7.7). Ca(2+) also forms a tetranuclear [Ca{Cu(H(-2)L)}]2(4+) species at a high Ca(2+) concentration. Tri- and tetranuclear calcium complexes show blue- and pink-colored crystals, respectively. [Cu(H(-2)L)] is the most active species in inducing DNA alterations. The DNA damages are compatible with its hydrolytic cleavages.

  13. Synthesis and biological activities of transition metal complexes based on acetylsalicylic acid as neo-anticancer agents.

    Science.gov (United States)

    Rubner, Gerhard; Bensdorf, Kerstin; Wellner, Anja; Kircher, Brigitte; Bergemann, Silke; Ott, Ingo; Gust, Ronald

    2010-10-14

    [(μ(4)-η(2))-(Prop-2-ynyl)-2-acetoxybenzoate]dicobalthexacarbonyl (Co-ASS), a derivative of aspirin (ASS), demonstrated high growth-inhibitory potential against various tumor cells with interference in the arachidonic acid cascade as probable mode of action. The significance of the kind of metal and cluster was verified in this structure-activity study: Co(2)(CO)(6) was respectively exchanged by a tetrameric cobalt-, trimeric ruthenium-, or trimeric ironcarbonyl cluster. Furthermore, the metal binding motif was changed from alkyne to 1,3-butadiene. Compounds were evaluated for growth inhibition, antiproliferative effects, and apoptosis induction in breast (MCF-7, MDA-MB 231) and colon cancer (HT-29) cell lines and for COX-1/2 inhibitory effects at isolated isoenzymes. Additionally, the major COX metabolite prostaglandin E2 (PGE(2)) was quantified in arachidonic acid-stimulated MDA-MB 231 breast tumor cells. It was demonstrated that the metal cluster was of minor importance for effects on cellular activity if an alkyne was used as ligand. Generally, no correlation existed between growth inhibition and COX activity. Cellular growth inhibition and antiproliferative activity at higher concentrations of the most active compounds Prop-ASS-Co(4) and Prop-ASS-Ru(3) correlated well with apoptosis induction.

  14. Synthesis, spectroscopic, coordination and biological activities of some transition metal complexes containing ONO tridentate Schiff base ligand.

    Science.gov (United States)

    Belal, A A M; El-Deen, I M; Farid, N Y; Zakaria, Rosan; Refat, Moamen S

    2015-01-01

    The main target of this paper is to get an interesting data for the preparation and characterizations of metal oxide (MO) nanoparticles using H2L Schiff base complexes as precursors through the thermal decomposition procedure. Five Schiff base complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions were synthesized from 2-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-benzoic acid new adduct (H2L). Theses complexes were characterized using infrared, electronic, mass and (1)H NMR spectroscopic techniques. The elemental analysis data was confirmed that the stoichiometry of (metal:H2L) is 1:1 molar ratio. The molar conductance indicates that all of complexes are non electrolytic. The general chemical formulas of these complexes is [M(L)(NH3)]·nH2O. All complexes are tetrahedral geometry. The thermal decomposition behavior of H2L hydrated and anhydrous complexes has been discussed using thermogravimetric analysis (TG/DTG) and differential thermal analyses (DTA) under nitrogen atmosphere. The crystalline phases of the reaction products were checked using X-ray diffractometer (XRD) and scanning electron microscopy (SEM). PMID:25989615

  15. Enhancing the mechanical and biological performance of a metallic biomaterial for orthopedic applications through changes in the surface oxide layer by nanocrystalline surface modification.

    Science.gov (United States)

    Bahl, Sumit; Shreyas, P; Trishul, M A; Suwas, Satyam; Chatterjee, Kaushik

    2015-05-01

    Nanostructured metals are a promising class of biomaterials for application in orthopedics to improve the mechanical performance and biological response for increasing the life of biomedical implants. Surface mechanical attrition treatment (SMAT) is an efficient way of engineering nanocrystalline surfaces on metal substrates. In this work, 316L stainless steel (SS), a widely used orthopedic biomaterial, was subjected to SMAT to generate a nanocrystalline surface. Surface nanocrystallization modified the nature of the oxide layer present on the surface. It increased the corrosion-fatigue strength in saline by 50%. This increase in strength is attributed to a thicker oxide layer, residual compressive stresses, high strength of the surface layer, and lower propensity for intergranular corrosion in the nanocrystalline layer. Nanocrystallization also enhanced osteoblast attachment and proliferation. Intriguingly, wettability and surface roughness, the key parameters widely acknowledged for controlling the cellular response remained unchanged after nanocrystallization. The observed cellular behavior is explained in terms of the changes in electronic properties of the semiconducting passive oxide film present on the surface of 316L SS. Nanocrystallization increased the charge carrier density of the n-type oxide film likely preventing denaturation of the adsorbed cell-adhesive proteins such as fibronectin. In addition, a net positive charge developed on the otherwise neutral oxide layer, which is known to facilitate cellular adhesion. The role of changes in the electronic properties of the oxide films on metal substrates is thus highlighted in this work. This study demonstrates the advantages of nanocrystalline surface modification by SMAT for processing metallic biomaterials used in orthopedic implants.

  16. Electrical Conductivity in Transition Metals

    Science.gov (United States)

    Talbot, Christopher; Vickneson, Kishanda

    2013-01-01

    The aim of this "Science Note" is to describe how to test the electron-sea model to determine whether it accurately predicts relative electrical conductivity for first-row transition metals. In the electron-sea model, a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalised valence…

  17. SYNTHESIS, STRUCTURE AND BIOLOGICAL ACTIVITY OF N(4-ALLYL-3-THIOSEMICARBAZONES AND THEIR COORDINATION COMPOUNDS WITH SOME 3D METALS

    Directory of Open Access Journals (Sweden)

    Vasilii GRAUR

    2016-02-01

    Full Text Available The paper presents a review of different N(4-allyl-3-thiosemicarbazones and their coordination compounds described in literature. N(4-allyl-3-thiosemicarbazide can form corresponding thiosemicarbazones with aliphatic, aromatic and heteroaromatic carbonyl compounds. In the presence of transitional metal ions they can form coordination compounds of different structures. Both coordination compounds and proligands manifest antitumor, antibacterial, antiviral, and antimalarial activities. Copper(II coordination compounds with these ligands manifest better antitumor activity than corresponding proligands. SINTEZA, STRUCTURA ŞI ACTIVITATEA BIOLOGICĂ A N(4-ALIL-3-TIOSEMICARBAZONELOR ŞI A COMPUŞILOR COORDINATIVI AI UNOR METALE 3D CU ACEŞTI LIGANZILucrarea prezintă o revistă a N(4-alil-3-tiosemicarbazonelor şi a compuşilor coordinativi cu aceşti liganzi descrise în literatura de specialitate. N(4-alil-3-tiosemicarbazida formează tiosemicarbazone cu aldehide şi cetone alifatice, aro­matice şi heteroaromatice. În prezenţa ionilor de metale de tranziţie acestea pot forma compuşi coordinativi cu diferite structuri. N(4-alil-3-tiosemicarbazonele şi compuşii coordinativi manifestă activitate antitumorală, antibacterială, antivirală şi antimalarică. Compuşii coordinativi ai cuprului cu aceşti liganzi manifestă activitate antitumorală sporită în comparaţie cu N(4-alil-3-tiosemicarbazonele corespunzătoare. 

  18. Studies on some metal complexes of quinoxaline based unsymmetric ligand: Synthesis, spectral characterization, in vitro biological and molecular modeling studies.

    Science.gov (United States)

    Dhanaraj, Chellaian Justin; Johnson, Jijo

    2016-08-01

    Mononuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes of an unsymmetric Schiff base ligand, 3-(-(3-(-3,5-dichloro-2-hydroxybenzylideneamino)propylimino)methyl)quinoxalin-2(1H) -one (L) were synthesized and characterized by various analytical and spectral techniques. The molar conductance values of metal complexes indicate non-electrolytic behavior of the metal complexes. The Schiff base act as tetra dentate ONNO donor ligand in Co(II), Ni(II), Zn(II) complexes and tridentate NNO donor in Cu(II) complex. Thermal stabilities of the newly synthesized compounds were determined by thermal analysis. Crystallinity, average grain size and unit cell parameters were determined from powder X-ray diffraction study. Electrochemical behaviors of the compounds were examined by cyclic voltammetry technique. The Schiff base and its complexes have been screened for their in vitro antimicrobial activities against some bacterial and fungal strains by disc diffusion method. The interaction of the compounds with calf thymus DNA (CT DNA) has been investigated by electronic absorption spectral titration and viscosity measurement (hydrodynamic) methods. Furthermore, the pUC18 DNA cleavage activities of the complexes have been explored. The compounds were also subjected to in vitro antioxidant, anticancer activity screening, druglikeness and bioactivity predictions using Molinspiration software. Molecular docking studies of the present compounds were carried out against B-DNA dodecamer d(CGCGAATTCGCG)2 and vascular endothelial growth factor receptor (VEGFR-2) kinase. Quantum chemical calculations were done with DFT method to determine the optimum geometry of the ligand and its metal complexes. From the quantum chemical parameters, the reactivity parameters of the compounds were established.

  19. Synthesis, characterization, molecular docking and biological studies of self assembled transition metal dithiocarbamates of substituted pyrrole-2-carboxaldehyde.

    Science.gov (United States)

    Nami, Shahab A A; Ullah, Irfan; Alam, Mahboob; Lee, Dong-Ung; Sarikavakli, Nursabah

    2016-07-01

    A series of self assembled 3d transition metal dithiocarbamate, M(pdtc) [where M=Mn(II), Fe(II), Co(II), Ni(II) and Cu(II)] have been synthesized and spectroscopically characterized. The bidentate dithiocarbamate ligand Na2pdtc (Disodium-1,4-phenyldiaminobis (pyrrole-1-sulfino)dithioate) was prepared by insertion reaction of carbondisulfide with Schiff base, N,N'-bis-(1H-pyrrol-2-ylmethylene)-benzene-1,4-diamine (L1) in basic medium. The simple substitution reaction between the metal halide and Na2pdtc yielded the title complexes in moderate yields. However, the in situ procedure gives high yield with the formation of single product as evident by TLC. Elemental analysis, IR, (1)H and (13)C NMR spectra, UV-vis., magnetic susceptibility and conductance measurements were done to characterize the complexes, M(pdtc). All the evidences suggest that the complexes have tetrahedral geometry excepting Cu(II) which is found to be square planar. A symmetrical bidentate coordination of the dithiocarbamato moiety has been observed in all the complexes. The conductivity data show that the complexes are non-electrolyte in nature. The anti-oxidant activity of the ligand, Na2pdtc and its transition metal complexes, M(pdtc) have been carried out using DPPH and Cu(pdtc) was found to be most effective. The anti-microbial activity of the Na2pdtc and M(pdtc) complexes have been carried out and on this basis the molecular docking study of the most effective complex, Cu(pdtc) has also been reported. PMID:27197060

  20. Studies on some metal complexes of quinoxaline based unsymmetric ligand: Synthesis, spectral characterization, in vitro biological and molecular modeling studies.

    Science.gov (United States)

    Dhanaraj, Chellaian Justin; Johnson, Jijo

    2016-08-01

    Mononuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes of an unsymmetric Schiff base ligand, 3-(-(3-(-3,5-dichloro-2-hydroxybenzylideneamino)propylimino)methyl)quinoxalin-2(1H) -one (L) were synthesized and characterized by various analytical and spectral techniques. The molar conductance values of metal complexes indicate non-electrolytic behavior of the metal complexes. The Schiff base act as tetra dentate ONNO donor ligand in Co(II), Ni(II), Zn(II) complexes and tridentate NNO donor in Cu(II) complex. Thermal stabilities of the newly synthesized compounds were determined by thermal analysis. Crystallinity, average grain size and unit cell parameters were determined from powder X-ray diffraction study. Electrochemical behaviors of the compounds were examined by cyclic voltammetry technique. The Schiff base and its complexes have been screened for their in vitro antimicrobial activities against some bacterial and fungal strains by disc diffusion method. The interaction of the compounds with calf thymus DNA (CT DNA) has been investigated by electronic absorption spectral titration and viscosity measurement (hydrodynamic) methods. Furthermore, the pUC18 DNA cleavage activities of the complexes have been explored. The compounds were also subjected to in vitro antioxidant, anticancer activity screening, druglikeness and bioactivity predictions using Molinspiration software. Molecular docking studies of the present compounds were carried out against B-DNA dodecamer d(CGCGAATTCGCG)2 and vascular endothelial growth factor receptor (VEGFR-2) kinase. Quantum chemical calculations were done with DFT method to determine the optimum geometry of the ligand and its metal complexes. From the quantum chemical parameters, the reactivity parameters of the compounds were established. PMID:27236046

  1. Selective separation of sodium ions from a mixture with phenylalanine by Donnan dialysis with a profiled sulfogroup cation exchange membrane

    Science.gov (United States)

    Vasil'eva, V. I.; Goleva, E. A.

    2013-11-01

    The possibility of separating ions of metal from a mixture with ampholyte (an amino acid) by Donnan dialysis with an MK-40 sulfogroup cation exchange membrane is demonstrated. Conditions ensuring the selectivity and intensity of the mass transfer of sodium ions from a mixture with bipolar phenylalanine ions into a diffusate containing hydrochloric acid through a cation exchange membrane are found.

  2. Synthesis, Characterization, and Biological Activity of Some Transition Metal Complexes of N-Benzoyl-N′-2-thiophenethiocarbohydrazide

    Directory of Open Access Journals (Sweden)

    Mahendra Yadav

    2012-01-01

    Full Text Available In the present study, Mn(II, Fe(II, Ni(II, and Cu(II complexes of N-benzoyl -N′-2-thiophenethiocarbohydrazide (H2 BTTH have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements, infrared, NMR, electronic, and ESR spectral studies. The complexes were found to have compositions [Mn(H BTTH2], [Ni(BTTH(H2O2], [Cu(BTTH], and [Fe(H BTTH2EtOH]. The antibacterial and antifungal properties of H2 BTTH and its metal complexes have been screened against several bacteria and fungi.

  3. Synthesis, metal ion binding, and biological evaluation of new anticancer 2-(2'-hydroxyphenyl)benzoxazole analogs of UK-1.

    Science.gov (United States)

    McKee, Mireya L; Kerwin, Sean M

    2008-02-15

    UK-1 is a bis(benzoxazole) natural product displaying activity against a wide range of human cancer cell lines. A simplified analog of UK-1, 4-carbomethoxy-2-(2'-hydroxyphenyl)benzoxazole, was previously found to be almost as active as UK-1 against cancer cell lines, and similar to the natural product, formed complexes with a variety of metal ions such as Mg2+ and Zn2+. A series of 4-substituted-2-(2'-hydroxyphenyl)benzoxazole analogs of this 'minimal pharmacophore' of UK-1 were prepared. The anti-cancer activity of these analogs was examined in breast and lung cancer cell lines. Spectrophotometric titrations in methanol were carried out in order to assess the ability of UK-1 and these analogs to coordinate with Mg2+ and Cu2+ ions. Although none of the new analogs were more cytotoxic than 4-carbomethoxy-2-(2'-hydroxyphenyl)benzoxazole, some analogs were identified that display similar cytotoxicity to this simplified UK-1 analog with improved water solubility. UK-1 and all of these new analogs bind Cu2+ ions better than Mg2+ ions, and the nature of the 4-substituent is important for the Mg2+ ion binding ability of these 2-(2'-hydroxyphenyl)benzoxazoles. Previous studies of a limited number of UK-1 analogs demonstrated a correlation between Mg2+ ion binding ability and cytotoxicity; however, within this series of 4-substituted-2-(2'-hydroxyphenyl)benzoxazoles the variations in cytotoxicity do not correlate with either Mg2+ or Cu2+ ion binding ability. These results, together with recent ESI-MS studies of Cu2+-mediated DNA binding by UK-1 and analogs, indicate that UK-1 and analogs may exert their cytotoxic effects by interaction with Cu2+ or other transition metal ions, rather than Mg2+, and that metal ion-mediated DNA binding, rather than metal ion binding affinity, is important for the cytotoxic effect of these compounds. The potential role of Cu2+ ions in the cytotoxic action of UK-1 is further supported by the observation that UK-1 in the presence of Cu2

  4. Tripodal Receptors for Cation and Anion Sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman,; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  5. Features definition exchange cations in sedimentary rocks.

    OpenAIRE

    Bilec'ka V.A.

    2008-01-01

    The research method of determination of exchange cations in calcareous sedimentary rocks of different extractants, the influence of the ratio between the solid and liquid phases on extrusion exchange cations.

  6. Features definition exchange cations in sedimentary rocks.

    Directory of Open Access Journals (Sweden)

    Bilec'ka V.A.

    2008-05-01

    Full Text Available The research method of determination of exchange cations in calcareous sedimentary rocks of different extractants, the influence of the ratio between the solid and liquid phases on extrusion exchange cations.

  7. Determination of noble metals in biological samples by electrothermal vaporization inductively coupled plasma mass spectrometry, following cloud point extraction

    Science.gov (United States)

    Andreia Mesquita da Silva, Márcia; Lúcia Azzolin Frescura, Vera; José Curtius, Adilson

    2001-10-01

    A simple separation procedure for noble metals based on cloud point extraction is proposed. The analyte ions in aqueous acidic solution, obtained by the acid digestion of the samples, were complexed with O, O-diethyl-dithiophosphate and Triton X-114 was added as a non-ionic surfactant. By increasing the temperature up to the cloud point, a phase separation occurs, resulting in an aqueous phase and a surfactant-rich phase containing most of the analytes that were complexed. The metals in the surfactant-rich phase were determined by electrothermal vaporization inductively coupled plasma mass spectrometry. The extraction conditions as well as the instrumental parameters were optimized. Enrichment factors ranging from 7 (Rh) to 60 (Pt) and limits of detection from 0.6 (Pt) to 3.0 ng l -1 (Rh) were obtained in the digested samples. The extraction was not efficient for Ir. Among the reference materials analyzed in this work, only one (SRM 2670, urine) presented recommended values for Au and Pt. Due to the non-availability of adequate CRMs, accuracy was assessed by spiking known analyte amounts to the acid digests. Recoveries close to 100% were observed for all the studied elements but Ru. Poor agreement between found and recommended values was observed for non-digested urine sample, probably due to the carrier effect of co-extracted residual matrix components. However, good agreement was reached after urine acid mineralization.

  8. Synthesis, spectroscopic characterization and biological activity of the metal complexes of the Schiff base derived from phenylaminoacetohydrazide and dibenzoylmethane

    Science.gov (United States)

    El-Tabl, Abdou Saad; El-Saied, Fathey A.; Plass, Winfried; Al-Hakimi, Ahmed Noman

    2008-11-01

    A new series of mono and binuclear Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), La(III), Ru(III), Hf(IV), ZrO(II) and UO 2(II) complexes of phenylaminodibenzoylhydrazone have been synthesized and characterized by elementals analyses, IR UV-vis spectra, magnetic moments, conductances, thermal analyses (DTA and TGA) and electron spin resonance (ESR) measurements. The IR spectral data show that, the ligand behaves as a neutral bidentate type ( 15 and 16), monobasic bidentate type ( 6), or monobasic tridentate type ( 5, 7, 8, 10, 11, 13, 14, 17- 21) or dibasic tridentate type 2- 4, 9 and 12 towards the metal ion. Molar conductances in DMF solution indicate that, the complexes are non-electrolytes. The ESR spectra of solid complexes ( 9 and 10) show axial and non-axial types indicating a d ground state with significant covalent bond character. However, complexes ( 11 and 12), show isotropic type, indicating manganese(II) octahedral geometry. Antibacterial and antifungal tests of the ligand and its metal complexes are also carried out and it has been observed that the complexes are more potent bactericides and fungicides than the ligand.

  9. New Transition and Actinide Metal Complexes of 2-Carboxyphenyl-hydrazo-Benzoylacetone Ligand:Synthesis,Characterization and Biological Study

    Institute of Scientific and Technical Information of China (English)

    KHALIL M.M.H.; MASHALY M.M.

    2008-01-01

    A new series of binary mononuclear complexes were prepared from the reaction of the hydrazone ligand,2-carboxyphenylhydrazo-benzoylacetone (H2L),with the metal ions,Cd(II),Cu(II),Ni(lI),Co01),Th(IV) and UO2(VI).The binary Cu(II) complex of H2L was reacted with the ligands 1,10-phenanthroline or 2-aminopyridine to form mixed-ligand complexes.The binary complexes of Cu(II) and Ni(II) are suggested to have octahedral configurations.The Cd(II) and Co(II) complexes are suggested to have tetrahedral and/or square-planar geometries,respectively.The Th(IV) and UO2(VI) complexes are suggested to have octahedral and dodecahedral geometries,respectively.The mixed-ligand complexes have octahedral configurations.The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses,conductance,IR and electronic absorption spectra,magnetic moments,1H NMR and TG-DSC measurements as well as by mass spectroscopy.The ligand and some of the metal complexes were found to activate the enzyme pectinlyase.

  10. Mapping the metal uptake in plants from Jasper Ridge Biological Preserve using synchrotron micro-focused X-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Allison [Univ. of California, Davis, CA (United States)

    2015-08-20

    Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentine-tolerant plants. Rye grown on potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.

  11. An amide-containing metal-organic tetrahedron responding to a spin-trapping reaction in a fluorescent enhancement manner for biological imaging of NO in living cells.

    Science.gov (United States)

    Wang, Jian; He, Cheng; Wu, Pengyan; Wang, Jing; Duan, Chunying

    2011-08-17

    Metal-organic polyhedra represent a unique class of functional molecular containers that display interesting molecular recognition properties and fascinating reactivity reminiscent of the natural enzymes. By incorporating a triphenylamine moiety as a bright blue emitter, a robust cerium-based tetrahedron was developed as a luminescent detector of nitronyl nitroxide (PTIO), a specific spin-labeling nitric oxide (NO) trapper. The tetrahedron encapsulates molecules of NO and PTIO within the cavity to prompt the spin-trapping reaction and transforms the normal EPR responses into a more sensitively luminescent signaling system with the limit of detection improved to 5 nM. Twelve-fold amide groups are also functionalized within the tetrahedron to modify the hydrophilic/lipophilic environment, ensuring the successful application of biological imaging in living cells.

  12. The Influence of Different Metallic Cations and TCE Initial Concentration on the Sorption Behavior of Organo-mineral Complexes%不同金属离子及三氯乙烯(TCE)初始浓度对有机-矿质复合体的吸附影响研究

    Institute of Scientific and Technical Information of China (English)

    张小亮; 何江涛; 石钰婷; 苏思慧; 李玮

    2013-01-01

    有机-矿质复合体对有机污染物的吸附,是直接影响有机污染物在地质环境中迁移、转化及归宿的重要因素,多价金属离子在有机质与粘土矿物相互作用形成复合体的过程中起到重要作用.为研究不同离子对有机质与粘土矿物的结合及其对有机污染物吸附行为的影响,以蒙脱土和腐植酸模拟地质吸附剂中的粘土矿物和有机质,分别加入Ca2+、Fe3+和Al3+金属离子,制备成有机质含量一定的不同离子有机-矿质复合体,进行对TCE的吸附批实验.结果表明,模拟土样Ca2+离子复合体直接拟合曲线在叠加计算曲线之上,而Fe3+和Al3+离子复合体直接拟合曲线均在叠加计算曲线之下,说明Ca2+离子的加入增强了有机-矿质复合体整体对TCE的吸附能力,Fe3+和Al3+离子有机-矿质复合体吸附性能则减弱;Ca2+、Fe3+和Al3+金属离子的加入均降低了复合体中有机质对TCE的亲合力,但Ca-M-HA复合体中有机质对TCE的亲合力强于Fe(Al)-M-HA复合体;TCE初始浓度对不同离子有机-矿质复合体的影响存在差异,在TCE低浓度段,复合体Kom值随着TCE浓度的增高而增大,且Ca-M-HA复合体较Al-M-HA和Fe-M-HA复合体增加幅度更大,在TCE高浓度段,TCE初始浓度对Al-M-HA和Fe-M-HA复合体Kom值的影响随着浓度的增加而减小后趋于稳定,而此时TCE初始浓度对Ca-M-HA复合体吸附行为影响仍然不能忽略.%Organo-mineral complexes are commonly distributed in natural environments. They play very important roles in regulating the transport and retention of hydrophobic organic contaminants in soils and sediments. Among the studies of organo-mineral complexes properties to their sorption characteristics, the significant of polyvalent metallic cations in banding organic matters(OM) to mineral surfaces should be taken into account. In order to examined the formation of organo-mineral complexes with different metallic cations and determined

  13. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  14. Interrelationships among biological activity, disulfide bonds, secondary structure, and metal ion binding for a chemically synthesized 34-amino-acid peptide derived from alpha-fetoprotein.

    Science.gov (United States)

    MacColl, R; Eisele, L E; Stack, R F; Hauer, C; Vakharia, D D; Benno, A; Kelly, W C; Mizejewski, G J

    2001-10-01

    A 34-amino-acid peptide has been chemically synthesized based on a sequence from human alpha-fetoprotein. The purified peptide is active in anti-growth assays when freshly prepared in pH 7.4 buffer at 0.20 g/l, but this peptide slowly becomes inactive. This functional change is proven by mass spectrometry to be triggered by the formation of an intrapeptide disulfide bond between the two cysteine residues on the peptide. Interpeptide cross-linking does not occur. The active and inactive forms of the peptide have almost identical secondary structures as shown by circular dichroism (CD). Zinc ions bind to the active peptide and completely prevents formation of the inactive form. Cobalt(II) ions also bind to the peptide, and the UV-Vis absorption spectrum of the cobalt-peptide complex shows that: (1) a near-UV sulfur-to-metal-ion charge-transfer band had a molar extinction coefficient consistent with two thiolate bonds to Co(II); (2) the lowest-energy visible d-d transition maximum at 659 nm, also, demonstrated that the two cysteine residues are ligands for the metal ion; (3) the d-d molar extinction coefficient showed that the metal ion-ligand complex was in a distorted tetrahedral symmetry. The peptide has two cysteines, and it is speculated that the other two metal ion ligands might be the two histidines. The Zn(II)- and Co(II)-peptide complexes had similar peptide conformations as indicated by their ultraviolet CD spectra, which differed very slightly from that of the free peptide. Surprisingly, the cobalt ions acted in the reverse of the zinc ions in that, instead of stabilizing anti-growth form of the peptide, they catalyzed its loss. Metal ion control of peptide function is a saliently interesting concept. Calcium ions, in the conditions studied, apparently do not bind to the peptide. Trifluoroethanol and temperature (60 degrees C) affected the secondary structure of the peptide, and the peptide was found capable of assuming various conformations in solution

  15. The role of metal ions in X-ray induced photochemistry

    CERN Document Server

    Stumpf, Vasili; Cederbaum, Lorenz S

    2015-01-01

    Metal ions play numerous important roles in biological systems being central to the function of biomolecules. In this letter we show that the absorption of X-rays by these ions leads to a complicated chain of ultrafast relaxation steps resulting in the complete degradation of their nearest environment. We conducted high quality ab initio studies on microsolvated Mg clusters demonstrating that ionisation of an 1s-electron of Mg leads to a complicated electronic cascade comprising both intra- and intermolecular steps and lasting only a few hundreds femtoseconds. The metal cation reverts to its original charge state at the end of the cascade, while the nearest solvation shell becomes multiply ionised and large concentrations of radical and slow electron species build up in the metal vicinity. We conclude that such cascades involving metal ions are essential for understanding the radiation chemistry of solutions and radiation damage to metal containing biomolecules.

  16. Organometallic cation-exchanged phyllosilicates

    OpenAIRE

    Fleming, Shay

    1991-01-01

    Organotin (IV) complexes formed between 0 01 M dimethyltin dichloride solutions prepared at pH 2 6 and 4 0, and trimethyltin chloride prepared at pH 3 4, with Na- 119 montmori 1lonite clay have been characterised using Sn Mflssbauer spectroscopy, X-ray diffraction, thermogravimetric analysis and water sorption isotherms Following cation exchange, Mttssbauer spectroscopy identified two tin species in the dimethyltin (IV)-exchanged clay prepared at pH 2 6 A cis specie...

  17. Analysis of bacteria, parasites, and heavy metals in lettuce (Lactuca sativa) and rocket salad (Eruca sativa L.) irrigated with treated effluent from a biological wastewater treatment plant.

    Science.gov (United States)

    Nikaido, Meire; Tonani, Karina A A; Julião, Fabiana C; Trevilato, Tânia M B; Takayanagui, Angela M M; Sanches, Sérgio M; Domingo, José L; Segura-Muñoz, Susana I

    2010-06-01

    This study aimed to evaluate the viability of using treated residuary water from the Biological Wastewater Treatment Plant of Ribeirão Preto to grow vegetables, through the characterization and quantification of parasites, coliforms, and heavy metals. Three equal cultivation areas were prepared. The first was irrigated with treated/chlorinated (0.2 mg L(-1)) wastewater, the second one with treated wastewater without chlorination, and the third site with potable water, which was the control group. The presence of Hymenolepis nana, Enterobius vermicularis, nematode larvae, and Entamoeba coli was verified in lettuce (Lactuca sativa) samples. Although nematode larvae were observed in rocket salad (Eruca sativa L.), no significant differences were found between the number of parasites and type of irrigation water used. No significant differences were found between the number of fecal coliforms in vegetables and the different types of irrigation. However, the vegetables irrigated with treated effluent without chlorination showed higher levels of fecal coliforms. The risk of pathogens is reduced with bleach addition to the treated effluent at 0.2 mg/L. Concentration of heavy metals in vegetables does not mean significant risks to human health, according with the parameters recommended by the World Health Organization.

  18. Analysis of bacteria, parasites, and heavy metals in lettuce (Lactuca sativa) and rocket salad (Eruca sativa L.) irrigated with treated effluent from a biological wastewater treatment plant.

    Science.gov (United States)

    Nikaido, Meire; Tonani, Karina A A; Julião, Fabiana C; Trevilato, Tânia M B; Takayanagui, Angela M M; Sanches, Sérgio M; Domingo, José L; Segura-Muñoz, Susana I

    2010-06-01

    This study aimed to evaluate the viability of using treated residuary water from the Biological Wastewater Treatment Plant of Ribeirão Preto to grow vegetables, through the characterization and quantification of parasites, coliforms, and heavy metals. Three equal cultivation areas were prepared. The first was irrigated with treated/chlorinated (0.2 mg L(-1)) wastewater, the second one with treated wastewater without chlorination, and the third site with potable water, which was the control group. The presence of Hymenolepis nana, Enterobius vermicularis, nematode larvae, and Entamoeba coli was verified in lettuce (Lactuca sativa) samples. Although nematode larvae were observed in rocket salad (Eruca sativa L.), no significant differences were found between the number of parasites and type of irrigation water used. No significant differences were found between the number of fecal coliforms in vegetables and the different types of irrigation. However, the vegetables irrigated with treated effluent without chlorination showed higher levels of fecal coliforms. The risk of pathogens is reduced with bleach addition to the treated effluent at 0.2 mg/L. Concentration of heavy metals in vegetables does not mean significant risks to human health, according with the parameters recommended by the World Health Organization. PMID:19639268

  19. Traffic-related heavy metals uptake by wild plants grow along two main highways in Hunan Province, China: effects of soil factors, accumulation ability, and biological indication potential.

    Science.gov (United States)

    Zhai, Yunbo; Dai, Qingyun; Jiang, Kang; Zhu, Yun; Xu, Bibo; Peng, Chuan; Wang, Tengfei; Zeng, Guangming

    2016-07-01

    This study was performed to investigate pollution of traffic-related heavy metals (HMs-Zn, Pb, Cu, Cr, and Cd) in roadside soils and their uptake by wild plants growing along highways in Hunan Province, China. For this, we analyzed the concentration and chemical fractionation of HMs in soils and plants. Soil samples were collected with different depths in the profile and different distances from highway edge. And leaves and barks of six high-frequency plants were collected. Results of the modified European Community Bureau of Reference (BCR) showed that the mobile fraction of these HMs was in the order of Cd > Pb > Zn > Cu > Cr. A high percentage of the mobile fraction indicates Cd, Pb, and Zn were labile and available for uptake by wild plants. The total concentration and values of risk assessment code (RAC) showed that Cd was the main risk factor, which were in the range high to very high risk. The accumulation ability of HMs in plants was evaluated by the biological accumulation factor (BAF) and the metal accumulation index (MAI), and the results showed that all those plant species have good phyto-extraction ability, while accumulation capacity for most HMs plants tissues was bark > leaf. The highest MAI value (5.99) in Cinnamomum camphora (L) Presl indicates the potential for bio-monitoring and a good choice for planting along highways where there is contamination with HMs. PMID:27026539

  20. Herbo-mineral based Schiff base ligand and its metal complexes: Synthesis, characterization, catalytic potential and biological applications.

    Science.gov (United States)

    Kareem, Abdul; Laxmi; Arshad, Mohammad; Nami, Shahab A A; Nishat, Nahid

    2016-07-01

    Schiff base ligand, (L), derived from condensation reaction of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, (curcumin), with pyridine-3-carboxamide, (nicotinamide), and its complexes of Co(II), Ni(II) and Cu(II) ions, containing 1,10-phenanthroline as auxiliary ligand were synthesized and characterized by various physico-chemical techniques. From the micro analytical data, the stoichiometry of the complexes 1:1 (metal: ligand) was ascertained. The Co(II) and Cu(II) forms octahedral complexes, while the geometric structure around Ni(II) atom can be described as square planar. The catalytic potential of the metal complexes have been evaluated by recording the rate of decomposition of hydrogen peroxide. The results reveal that the percent decomposition of H2O2increases with time and the highest value (50.50%) was recorded for Co(II) complex. The ligand and its complexes were also screened for their in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes and Pseudomonas aeruginosa. The relative order of antibacterial activity against S. Pyogenes, S. aureus and E. coli is Cu(II)>Ni(II)>Co(II)>(L); while with P. aeruginosa, K. pneumoniae the order of activity is Cu(II)>Co(II)>Ni(II)>(L). The anthelmintic screening was performed using Pheretima posthuma. The order of anthelmintic activity of ligand and its complexes is [(Phen)CuLCl2]>[(Phen)CoLCl2]>[(Phen)NiL]Cl2>(L). PMID:27107703

  1. Composition of outer-sphere cations as a tool for electrochemical synthesis of novel niobium compounds

    Directory of Open Access Journals (Sweden)

    Grinevitch V.V.

    2003-01-01

    Full Text Available The individual alkali-metal cation influence on the chemical and phase composition of electrosynthesis products has been studied in fluoride solvents with different O/Nb ratios. It was shown that the cation nature of molten electrolytes is a powerful tool to control the chemical and phase composition of the cathodic products of electrolysis in oxy-fluoride and fluoride melts. New niobium compounds were obtained by electrochemical synthesis using the outer-sphere cations composition control: tetragonal Nb6O, rhombohedral sub-oxide NbxO (x<6 and composite compounds "NbO" ⋅n"MeF" (Me=K, Rb, n=1, 2.

  2. Working at higher magnifications in scanning electron microscopy with secondary and backscattered electrons on metal coated biological specimens and imaging macromolecular cell membrane structures.

    Science.gov (United States)

    Peters, K R

    1985-01-01

    Membrane structures of macromolecular dimensions were imaged with high resolution secondary electron type I (SE-I) signal contrasts on metal coated biological specimens. The quality of the surface information was strongly dependent on the signal used for microscopy and on the properties of metal films, i.e., thickness, continuity, structure and decoration effects. Films of 10 nm thickness produced so much type II electrons that identical images were obtained with the conventional SE-II and BSE-II signals. In such images, the type I SE signal was so low that only very weak contrasts were recognizable. If the films--continuous or discontinuous--were composed of large metal aggregates (gold and platinum) a strong micro-roughness contrast was produced by the type II signal. At high magnifications (100,000 x) this background signal greatly reduced the S/N ratio of the SE-I signal. A similar effect was previously shown to be produced by the type III background signal. The type II background signal minimized when continuous films of small aggregates (tantalum and chromium) were applied. SE-I contrast dominated in the image if the film thickness was limited to 1 nm. Additionally, it was found that gold and platinum decorated membrane surface structures, less than 20 nm in size, and did not reveal all the topographic information available (size, shape, orientation spacing of small surface features) but merely displayed center-to-center distances. These decoration effects were avoided and extensive topographic information was obtained through surface coating with Ta or Cr. PMID:4095499

  3. Soluble metals in the atmosphere and their biological implications. A study to identify important aerosol components by statistical analysis of PIXE data.

    Science.gov (United States)

    Winchester, J W

    1990-01-01

    Multivariate statistical analysis has been applied to time series measurements of aerosol elemental composition from PIXE analysis of filter samples, and principal components have been resolved that represent distinct particle types in an external mixture in the atmosphere. In this study, it is argued that a combination of chemical and statistical analyses of the data may be more powerful in determining chemical species in atmospheric aerosols than studied that employ mainly direct chemical analysis of chemical species in unresolved mixtures of aerosol particle samples. Sulfur is generally associated with mineral dust elements. It is reasoned that the association may represent sulfuric acid coatings on particles that can lead to mineral dissolution and solubilization of significant amounts of aluminum, iron, and other metals. Upon wet or dry deposition to the surface, the fluxes of these metals in biologically-available form may be sufficient to affect primary productivity in the world ocean and cause ecological damage in lakes. As a consequence, the fluxes of biogenic trace gases to the atmosphere may be changed, possibly leading to changes in the tropospheric concentration of ozone. The inputs to lakes of soluble aluminum, which is toxic to fish, may be partly by deposition directly from the atmosphere, thus not limited to leaching of soils by acid deposition. Human inhalation of soluble aluminum and other solubilized mineral metals may account, in part, for the observed geographic pattern of deaths attributed to chronic obstructive pulmonary disease (COPD) that show high rates in cities of the Western US and the southeast region, but low in most of the midwest and northeast.

  4. Title: The validation of Cryogenic Laser Ablation ICP-MS (CLA-ICP-MS) methods by comparison to laser ablation (LA)-ICP-MS and solution based ICP-MS methods, for the analysis of metals in biological tissues

    Science.gov (United States)

    Hannigan, R.; Darrah, T. H.; Horton, M.

    2009-12-01

    ICP-MS and laser ablation ICP-MS (LA-ICP-MS) are well established techniques for the analysis of metals in geological and environmental samples. LA-ICP-MS is commonly used in geological applications to determine the spatial distribution of metal concentrations at small sampling intervals (as low as 10 microns). However, measurement of metals in water-rich, soft biological tissues typically requires samples to be digested into solutions, obfuscating spatial variations in metal concentrations. The cryogenic cell solidifies (by freezing) soft tissue, allowing these tissues to be analyzed by laser ablation for spatial variations in metal concentration. The cell is temperature programmable and capable of maintaining a sample at any temperature between -35C and 25C throughout prolonged analysis. We validate the cryogenic laser ablation ICP-MS (CLA-ICP-MS) method using NIST Glass SRM 612. We also compare metal concentration data analyzed by cryogenic laser ablation ICP-MS (CLA-ICP-MS), LA-ICP-MS, and solution based ICP-MS, for human and rodent brain samples. The cryogenic laser ablation cell will expand analytical capabilities for measuring spatial distribution and concentration of metals incorporated into biological tissues.

  5. Cationic Organic/Inorganic Hybrids and Their Swelling Properties

    Institute of Scientific and Technical Information of China (English)

    E. S. Dragan; L. Ghimici; M. Cazacu

    2005-01-01

    @@ 1Introduction Specific properties of poly(dimethylsiloxanes), such as low glass transition temperature, low surface energy, good insulating properties, biological and chemical inertness, high diffusion coefficient of gases, make them very attractive for practical applications in the daily life. However, there is a great interest last time in the preparation of ionic organic/inorganic materials with new properties for new applications. Quaternary ammonium salt(QAS) groups included in siloxane copolymers could induce new interesting properties such as:permanent fungicidal and bactericidal properties, which make them very attractive as materials for sanitary applications, improved selectivity coefficients of the gas-separation membranes, ion-exchange properties and so forth. So far, QAS groups have been located in the side chain[1,2]. Our interest was focused on the preparation of some novel cationic polysiloxane copolymers containing QAS groups of both integral type and pendent type[3,4]. Our objectives for the present study concern the synthesis of some cationic organic/siloxane hybrid materials with swelling properties controlled by both the nature of cationic organic component and the ratio between the organic and inorganic counterparts. Such cationic hybrid materials could be of interest for the preparation of new stimuli-responsive hydrogels[5,6].

  6. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    Science.gov (United States)

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-01-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints. PMID:27345704

  7. Synthesis, spectral characterization, molecular modeling, thermal study and biological evaluation of transition metal complexes of a bidentate Schiff base ligand

    Science.gov (United States)

    Chandra, Sulekh; Bargujar, Savita; Nirwal, Rita; Qanungo, Kushal; Sharma, Saroj K.

    2013-09-01

    Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized [where L = 3-Bromoacetophenone thiosemicarbazone and X = CH3COO-, Cl- and NO3-]. All the complexes were characterized by elemental analysis, magnetic moments, IR, electronic and EPR spectral studies. The ligand behaved as bidentate and coordinated through sulfur of sbnd Cdbnd S group and nitrogen atoms of sbnd Cdbnd N group. The copper(II) and nickel(II) complexes were found to have magnetic moments 1.94-2.02 BM, 2.96-3.02 BM respectively which was corresponding to one and two unpaired electrons respectively. The molar conductance of the complexes in solution of DMSO lies in the range of 10-20 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of EPR, electronic and infrared spectral studies, tetragonal geometry has been assigned for copper(II) complexes and an octahedral geometry for nickel(II) complexes. The values of Nephelauxetic parameter β lie in the range 0.19-0.37 which indicated the covalent character in metal ligand ‘σ' bond. Synthesized ligand and its copper(II) and nickel(II) complexes have also been screened against different bacterial and fungal species which suggested that complexes are more active than the ligands in antimicrobial activities.

  8. The effect of Ca-diethylenetriamine pentaacetate on the biological behaviour of tumour-affine metal complexes

    International Nuclear Information System (INIS)

    The complexon CaDTPA was injected into tumour-bearing mice in concentrations of 0.05, 0.1, 0.3 and 0.6 mole/l (pH:6) 30 min after the 168Yb-injection. 100 μl of a 0.3 M CaDTPA solution were injected at different time points (simultaneously, 2, 5, 10, 20, 30, 40 and 50 min, 1, 1.25, 1.5, 2.5 and 10 h) after 169Yb-citrate injection. The animals were killed 24 h after radionuclide administration. A strong radioactivity decrease was observable 24 h p.i. not only in blood, liver, spleen, muscle and bone but also in the tumour if CaDTPA was administered within the first 2 h after ytterbium injection. Thereafter no change in radioactivity could be achieved by DTPA. A time phase in which the Yb could be eliminated from the tissues by means of DTPA (time intervals (5 h). This indicates that the incorporation of Yb into the cells is completed after 5 h and that the metals are intracellulary bound, probably to the lysosomes. Improvements of the scintigraphic tumour detection cannot be expected from the use of complexones. (orig.)

  9. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    Science.gov (United States)

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-06-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints.

  10. Novel Cholesterol-Based Cationic Lipids as Transfecting Agents of DNA for Efficient Gene Delivery

    Directory of Open Access Journals (Sweden)

    Jia Ju

    2015-03-01

    Full Text Available The design, synthesis and biological evaluation of the cationic lipid gene delivery vectors based on cholesterol and natural amino acids lysine or histidine are described. Cationic liposomes composed of the newly synthesized cationic lipids 1a or 1b and neutral lipid DOPE (1,2-dioleoyl-l-α-glycero-3-phosphatidyl-ethanolamine exhibited good transfection efficiency. pEGFP-N1 plasmid DNA was transferred into 293T cells by cationic liposomes formed from cationic lipids 1a and 1b, and the transfection activity of the cationic lipids was superior (1a or parallel (1b to that of the commercially available 3β-[N-(N',N'-dimethylaminoethyl-carbamoyl] cholesterol (DC-Chol derived from the same cholesterol backbone with different head groups. Combined with the results of agarose gel electrophoresis, transfection experiments with various molar ratios of the cationic lipids and DOPE and N/P (+/− molar charge ratios, a more effective formulation was formed, which could lead to relatively high transfection efficiency. Cationic lipid 1a represents a potential agent for the liposome used in gene delivery due to low cytotoxicity and impressive gene transfection activity.

  11. Engelmann Spruce (Picea engelmannii) as a biological monitor of changes in soil metal loading related to past mining activity

    Science.gov (United States)

    Witte, K.M.; Wanty, R.B.; Ridley, W.I.

    2004-01-01

    Engelmann spruce (Picea engelmannii) is the dominant tree species in many abandoned mine areas of the Rocky Mountains. It is long-lived, and therefore, may act as a long term biological monitor of changes in soil chemistry caused by past mining activity. In this study, laser ablation inductively coupled mass spectrometry (LA-ICPMS) was used to analyze individual tree rings of Engelmann spruce for Fe, Zn, Cu, Cd, Mn, Pb and Sr concentrations. Cores were obtained from trees growing in tailings-impacted and control (non-tailings impacted) sites near the Waldorf mine (Waldorf, CO, USA). Zinc, Cu, Fe, Cd, Pb and Sr concentrations remained low and consistent over time in the control tree rings. However, in the tailings impacted cores, concentrations of Zn, Cu, Fe and Cd increase significantly in post-mining rings. In addition, Zn, Cu, Fe, and Cd concentrations in pre-mining rings of both the control and tailings impacted cores are similar, indicating that present day soil concentrations of these elements in the control area are a reasonable estimation of background for this area. Lead and Sr concentrations in control and tailings-impacted rings remained similar and relatively constant through time and are not useful in determining changes in soil chemistry due to past mining activity. ?? 2004 Elsevier Ltd. All rights reserved.

  12. Prospects of metal research

    International Nuclear Information System (INIS)

    Topical questions about modern metal research are considered covering fundamentals and applications. Many, hitherto undeveloped distinguished properties of metals, such as resistance against particle and quantum radiations, neutrons, very high and very low temperatures , stresses, and chemical agents; memory effects; superconductivity etc. are pointed out. The following topics are treated: subject and methodology of the science of metals, significance of metals; discovery of new properties of metallic materials; theory of metallic alloys; extreme conditions; intermetallic compounds, polymorphic metals; rare metals (rare earth metals, rhenium, noble metals); questions of strength and technology of metals and alloys; temperature zones of brittle fracture in metals and alloys; alloys with particular electrophysical properties; superconductive metalic materials; 'biological' science of metals; and conclusions. The booklet will be useful for students at technical schools and universities as well as for engineers and scientists engaged in metal research

  13. Characterization of a New Family of Metal Transporters

    Energy Technology Data Exchange (ETDEWEB)

    Mary Lou Geurinot; David Eide

    2002-04-29

    Metal ions are critical nutrients, yet overaccumulation of these same metals can also be toxic. To maintain appropriate intracellular levels, cells require specific metal uptake systems that are subject to precise homeostatic regulation. The long-range goal of our research is to define the molecular mechanism(s) and regulation of metal ion uptake in eukaryotic cells. Integrating genetic, molecular biological and biochemical approaches, we have examined these processes in the yeast Saccharomyces cerevisiae and the plant Arabidopsis thaliana. Both are proven model systems for studying fundamental cellular processes. Our work has focused on the ZIP family of metal transporters which we identified; this family has representatives in bacteria, fungi, plants and animals. IRT, one of the founding members of the ZIP family, is an essential cation transporter that is expressed in the epidermal cells of iron deficient plant roots and is responsible for uptake of iron from the soil. We now know that there are 15 ZIP genes in the Arabidopsis and the similarities among their encoded gene products. The ZIP family members display different substrate specificities for metals and different tissue distributions in Arabidopsis. Moreover, the family members respond differentially to metal deficiencies. For example, IRT1, ZIP6 and ZIP9 mRNA are expressed mainly in the roots of iron deficient plants whereas ZIP4 responds to both iron and zinc deficiency. Work in both yeast and Arabidopsis has addressed substrate specificity as well as how these transporters are regulated in response to metal availability

  14. Stress and toxicity of biologically important transition metals (Co, Ni, Cu and Zn) on phytoplankton in a tropical freshwater system: An investigation with pigment analysis by HPLC

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Babu, P.V.R.; Acharyya, T.; Bandyopadhyay, D.

    contaminated water imposed by these four metals. Shift in community structure of phytoplankton and their different tolerance levels for different metals were also investigated. It was found that the variation of metal concentrations at lower level (1 x 10 sup...

  15. Use of laser induced photoacoustic spectroscopy (LIPAS) to determine equilibrium constants of cation-cation complexes

    International Nuclear Information System (INIS)

    Laser Induced PhotoAcoustic Spectroscopy (LIPAS) is a relatively new, photothermal technique to examine solutions. Studies in the past have shown it to be more sensitive than conventional absorption spectroscopy, while, yielding the same information thus allowing lower concentrations to be used. This study is using LIPAS to examine solutions to determine the equilibrium constants of cation-cation complexes. It has been found that actinyl(V) cations form cation-cation complexes with a variety of cations, including actinyl(VI) cations. The radioactive nature of the actinide elements requires special handling techniques and also require limits be placed on the amount of material that can be used. The sensitivity of some oxidation states of the actinides to oxygen also presents a problem. Preliminary results will be presented for actinyl(V)-actinyl(VI) cation-cation complexes that were studied using a remote LIPAS system incorporating fiber optics for transmission of laser signals

  16. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  17. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya, E-mail: divya@chem.unipune.ac.in

    2015-05-15

    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu{sup 2+}, Fe{sup 2+}, Ni{sup 2+} and Zn{sup 2+} in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu{sup 2+}, Fe{sup 2+} and Ni{sup 2+} caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe{sup 2+}, Cu{sup 2+}, Ni{sup 2+} and Zn{sup 2+}. • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions.

  18. Molecular Design of Crown Ethers.22.Synthesis of Benzocrown Ether Derivatives and Their Solvent Extraction with Univalent/Bivalent Metal Picrates

    Institute of Scientific and Technical Information of China (English)

    YANG,Ying-Wei(杨英威); LI,Chun-Ju(李春举); ZHANG,Heng-Yi(张衡益); LIU,Yu(刘育)

    2004-01-01

    Three novel benzocrown ether derivatives have been synthesized and their cation binding behavior with uniand bi-valent metal ions was evaluated by the solvent extraction of aqueous metal picrates. The obtained results indicate that the size-fit of crown ether and metal cation, and electron effect of the side arm attached to benzocrown ethers affect their cation binding ability and selectivity.

  19. 航空煤油在不同价态金属离子交换介孔材料上的深度吸附脱硫%Deep desulfurization of jet fuel by adsorption over mesoporous materials exchanged with different metal cations

    Institute of Scientific and Technical Information of China (English)

    邱国欢; 孟祥瑞; 王玉和

    2013-01-01

    Three adsorbents were prepared by exchanging Ag+, Ni2+ and Ce3+ onto the aluminized large-pore-size SBA-15 (SBA-15-L). Desulfurization of model jet fuel containing 0.015(wt)% S were carried out using fixed-bed reactor. The results showed that the jet fuel can be desulfurized to 0.000l(wt)%. The sulfur capacity of Ag/Al-SBA-15-L was stronger than that of Ni/Al-SBA-15-L and Ce/Al-SBA-15-L L ICP-AES results exhibited that the loadings of Ag+ on the sorbent were 13 and 65 times as large as that of Ni2+ and Ce3+. The experiments of desulfurization illustrated that the ratios of adsorbed sulfur per Ag+, Ni2+ and Ce3+ cation were 0.027, 0.570 and 0.752 at adsorption saturation. And then, it was showed that the inherent sulfur capacity of these metal cations followed the order: Ce3+ > Ni2+> Ag+.%采用离子交换法,将不同价态的金属离子Ag+,Ni2+,Ce3+交换到铝化的大孔径SBA-15介孔材料(SBA-15-L)上,制备了吸附剂Ag/Al-SBA-15-L,Ni/Al-SBA-15-L,Ce/Al-SBA-15-L.脱硫实验表明,所制备的吸附剂可将硫含量为0.015(wt)%的模拟航空煤油,脱硫至硫含量低于0.0001 (wt)%,并且Ag/Al-SBA-15-L的吸附脱硫能力强于Ni/Al-SBA-15-L和Ce/Al-SBA-15.通过ICP-AES分析表明,在铝化的大孔SBA-15上,Ag+的交换量分别是Ni2+和Ce3+的13和65倍.达到吸附饱和时,每个活性中心离子Ag+、Ni2+、Ce3+上可分别吸附0.027,0.570,0.752个硫原子,即金属离子固有的吸附脱硫能力为Ce3+> Ni2+> Ag+.

  20. Adsorptive Desulfurization of Gasoline With Ag(Ⅰ)-Based Cationic Metal-Organic Frameworks%Ag(Ⅰ)金属有机骨架材料在汽油吸附脱硫中的应用

    Institute of Scientific and Technical Information of China (English)

    许敏; 刘丹; 桂建舟; 孟祥巍; 林赛燕; 马娟娟; 姜燕

    2012-01-01

    The desulfurization of model gasoline containing 500 jig/g sulfur by selective adsorption over the metal - organic frameworks (MOFs) of Ag2 (4 .4'- bipy), - (O3SCH2CH2SOs >, Ag<4 ,4- bipy)NO, and Ag(4 .4'-bipy)ClO, were studied in a static adsorbent at ambient temperature and pressure by using model fuels. The results show that adsorption rate of Ag2 (4,4 - bipy)2 - (OsSCH..CH2S()3), Ag(4.4'- bipy)NO, and Ag(4,4- bipy)CK), reached 70%, and the adsorptive selectivity of Ag2(4, 4'-bipy)2 - (O3CH2CH2SO2 ) and Ag(4, 4'- bipy) CIO, to thiophene wouldn't decrease significantly as the concentration of 1-octene increases. Moreover, for the silver-based MOF materials, there is a slight change on their framework after regeneration, however it wont lead to obvious change on the adsorption performance. Meanwhile deep desulfurization of real gasoline were also carried out, and find that sulphur content can decreased from the initial 70 fig/g to 8 μg/g over Ag2 (4,4-bipy)2-(OiSCH.CHjSOs ), and no obvious decrease in desulfurization capability can be observed after recycling 5 times.%以金属骨架材料Ag2(4,4'-bipy)2-(O3SCH2CH2SO3),Ag(4,4-bipy)NO3和Ag(4,4-bipy)ClO4为吸附剂,在常温常压下,研究了不同剂油物质的量比条件下的吸附脱硫效果,并测试了在不同1-辛烯含量的模拟油(含硫质量分数为500 μg/g)中的脱硫效果.结果表明:3种吸附剂在吸附前后晶体骨架结构略有改变;对噻吩的吸附程度都能达到70%左右;随着吸附剂含量的增加,脱硫率明显增加,最多的Ag2(4,4'-bipy)2-(O3SCH2CH2SO3)可以增加12.22%; 1-辛烯含量对Ag2(4,4'-bipy)2-(O3SCH2CH2SO3)的脱硫效果没有明显影响.同时Ag2(4,4'-bipy)2-(O3SCH2CH2SO3)对真实汽油的吸附脱硫实验表明:在常温常压下,真实汽油含硫质量分数可从70 μg/g降低到8 μg/g;再生后的吸附剂重复使用5次其吸附性能基本不变.

  1. Ag(I), Pb(II) and Hg(II) binding to biomolecules studied by Perturbed Angular Correlation of $\\gamma$-rays (PAC) spectroscopy: Function and toxicity of metal ions in biological systems

    CERN Multimedia

    Metal ions display diverse functions in biological systems and are essential components in both protein structure and function, and in control of biochemical reaction paths and signaling. Similarly, metal ions may be used to control structure and function of synthetic biomolecules, and thus be a tool in the design of molecules with a desired function. In this project we address a variety of questions concerning both the function of metal ions in natural systems, in synthetic biomolecules, and the toxic effect of some metal ions. All projects involve other experimental techniques such as NMR, EXAFS, UV-Vis, fluorescence, and CD spectroscopies providing complementary data, as well as interpretation of the experimental data by quantum mechanical calculations of spectroscopic properties.

  2. Potentiometric studies on ternary complexes involving some divalent transition metal ions, gallic acid and biologically abundant aliphatic dicarboxylic acids in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Abdelatty Mohamed Radalla

    2015-06-01

    Full Text Available Formation of binary and ternary complexes of the divalent transition metal ions, Cu2+, Ni2+, Co2+ and Zn2+ with gallic acid and the biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids were investigated by means of the potentiometric technique at 25 °C and I = 0.10 mol dm−3 NaNO3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of gallic acid and aliphatic dicarboxylic acids were determined and used for determining the stability constants of the binary and ternary complexes formed in the aqueous medium under the above experimental conditions. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes are inferred from the corresponding potentiometric pH-metric titration curves. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The values of Δ log K, percentage of relative stabilization (%R.S. and log X were evaluated and discussed. The concentration distribution of the various complex species formed in solution was evaluated and discussed. The mode of chelation of ternary complexes formed was ascertained by conductivity measurements.

  3. Theoretical study of the influence of cation vacancies on the catalytic properties of vanadium antimonate

    Energy Technology Data Exchange (ETDEWEB)

    Messina, S. [Laboratorio de Procesos Cataliticos, Departamento de Ingenieria Quimica, FIUBA, Pabellon de Industrias, Ciudad Universitaria, (1428) Capital Federal (Argentina); Juan, A. [Departamento de Fisica, UNS, Av. Alem 1253, (8000) Bahia Blanca (Argentina)], E-mail: cajuan@uns.edu.ar; Larrondo, S.; Irigoyen, B.; Amadeo, N. [Laboratorio de Procesos Cataliticos, Departamento de Ingenieria Quimica, FIUBA, Pabellon de Industrias, Ciudad Universitaria, (1428) Capital Federal (Argentina)

    2008-07-15

    We have theoretically studied the influence of antimony and vanadium cation vacancies in the electronic structure and reactivity of vanadium antimonate, using molecular orbital methods. From the analysis of the electronic properties of the VSbO{sub 4} crystal structure, we can infer that both antimony and vanadium vacancies increase the oxidation state of closer V cations. This would indicate that, in the rutile-type VSbO{sub 4} phase the Sb and V cations defects stabilize the V in a higher oxidation state (V{sup 4+}). Calculations of the adsorption energy for different toluene adsorption geometries on the VSbO{sub 4}(1 1 0) surface have also been performed. The oxidation state of Sb, V and O atoms and the overlap population of metal-oxygen bonds have been evaluated. Our results indicate that the cation defects influence in the toluene adsorption reactions is slight. We have computed different alternatives for the reoxidation of the VSbO{sub 4}(1 1 0) surface active sites which were reduced during the oxygenated products formation. These calculations indicate that the V cations in higher oxidation state (V{sup 4+}) are the species, which preferentially incorporate lattice oxygen to the reduced Sb cations. Thus, the cation defects would stabilize the V{sup 4+} species in the VSbO{sub 4} structure, determining its ability to provide lattice oxygen as a reactant.

  4. Cation Intercalation in Manganese Oxide Nanosheets: Effects on Lithium and Sodium Storage.

    Science.gov (United States)

    Lu, Ke; Hu, Ziyu; Xiang, Zhonghua; Ma, Jizhen; Song, Bin; Zhang, Jintao; Ma, Houyi

    2016-08-22

    The rapid development of advanced energy-storage devices requires significant improvements of the electrode performance and a detailed understanding of the fundamental energy-storage processes. In this work, the self-assembly of two-dimensional manganese oxide nanosheets with various metal cations is introduced as a general and effective method for the incorporation of different guest cations and the formation of sandwich structures with tunable interlayer distances, leading to the formation of 3D Mx MnO2 (M=Li, Na, K, Co, and Mg) cathodes. For sodium and lithium storage, these electrode materials exhibited different capacities and cycling stabilities. The efficiency of the storage process is influenced not only by the interlayer spacing but also by the interaction between the host cations and shutter ions, confirming the crucial role of the cations. These results provide promising ideas for the rational design of advanced electrodes for Li and Na storage. PMID:27458045

  5. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  6. Mobilization of Roadside Soil Cation Pools by Exchange with Road Deicers

    Science.gov (United States)

    Rossi, R.; Bain, D.

    2014-12-01

    Over the past sixty years, road deicers (i.e., road salt) have been applied to roadways in high latitudes to improve traffic conditions in winter weather. However, the dissolution of road deicers in highway runoff create waters with high total dissolved solids (TDS), specifically high concentrations of sodium, which can mobilize soil metals via soil cation exchange reactions. While several studies have detailed the interactions of high TDS solutions and surface and ground waters, limited attention is paid to the impacts of high TDS solutions on near-road soils. Between 2013 and 2014, soil water samples were collected from a roadside transect of lysimeter nests in Pittsburgh, PA. Soil water samples were analyzed for metal concentrations and resulting data used to examine cation dynamics. Patterns in soil water calcium and magnesium concentrations follow patterns in soil water sodium concentrations. In our samples, the highest major cation concentrations are found at the deepest lysimeters, suggesting major cations are mobilized to, and potentially accumulate in, deeper soil horizons. Concentration peaks in the downslope soil waters lag concentration peaks at the near-road nest by two months, indicating that road salt plumes persist and migrate following the road salting season. Characterizing the interactions of high TDS solutions and roadside soil cation pools clarifies our understanding of metal dynamics in the roadside environment. A deeper understanding of these processes is necessary to effectively restore and manage watersheds as high TDS solutions (i.e., road deicing, hydraulic fracturing, and marginal irrigation water) increasingly influence ecosystem function.

  7. Controlling potassium selectivity and proton blocking in a hybrid biological/solid-state polymer nanoporous membrane.

    Science.gov (United States)

    Balme, Sébastien; Picaud, Fabien; Kraszewski, Sebastian; Déjardin, Philippe; Janot, Jean Marc; Lepoitevin, Mathilde; Capomanes, Jhon; Ramseyer, Christophe; Henn, François

    2013-05-01

    Specific separations of protons and cations are usually performed by electromembrane processes, which require external electric energy. An easier process would be using a membrane able to separate both entities by passive diffusion. Presently, such synthetic nanoporous membranes do not exist. Here, we report the production of a robust hybrid biological/artificial solid-state membrane, which allows selective permeation of alkali metal cations without competing or concurrent permeation of protons. This membrane is simple to prepare and is based on the hydrophobic nature of the polymeric pore walls, and the confined gramicidin A molecules within. This work opens a new route for separation in the domain of nanobiofiltration, especially for tunable nanodevices based on differential ion conduction, with a fundamental understanding of the confinement mechanism.

  8. A REVIEW OF HEAVY METAL ADSORPTION BY MARINE ALGAE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Accumulation of heavy metals by algae had been studied extensively for biomonitoring or bioremediation purposes. Having the advantages of low cost raw material, big adsorbing capacity, no secondary pollution, etc., algae may be used to treat industrial water containing heavy metals. The adsorption processes were carried out in two steps: rapid physical adsorption first, and then slow chemical adsorption. pH is the major factor influencing the adsorption. The Freundlich equation fitted very well the adsorption isotherms. The uptake decreased with increasing ionic strength. The principal mechanism of metallic cation sequestration involves the formation of complexes between a metal ion and functional groups on the surface or inside the porous structure of the biological material. The carboxyl groups of alginate play a major role in the complexation. Different species of algae and the algae of the same species may have different adsorption capacity. Their selection affinity for heavy metals was the major criterion for the screening of a biologic adsorbent to be used in water treatment. The surface complex formation model (SCFM) can solve the equilibrium and kinetic problems in the biosorption.

  9. Cholesterol derived cationic lipids as potential non-viral gene delivery vectors and their serum compatibility.

    Science.gov (United States)

    Ju, Jia; Huan, Meng-Lei; Wan, Ning; Hou, Yi-Lin; Ma, Xi-Xi; Jia, Yi-Yang; Li, Chen; Zhou, Si-Yuan; Zhang, Bang-Le

    2016-05-15

    Cholesterol derivatives M1-M6 as synthetic cationic lipids were designed and the biological evaluation of the cationic liposomes based on them as non-viral gene delivery vectors were described. Plasmid pEGFP-N1, used as model gene, was transferred into 293T cells by cationic liposomes formed with M1-M6 and transfection efficiency and GFP expression were tested. Cationic liposomes prepared with cationic lipids M1-M6 exhibited good transfection activity, and the transfection activity was parallel (M2 and M4) or superior (M1 and M6) to that of DC-Chol derived from the same backbone. Among them, the transfection efficiency of cationic lipid M6 was parallel to that of the commercially available Lipofectamine2000. The optimal formulation of M1 and M6 were found to be at a mol ratio of 1:0.5 for cationic lipid/DOPE, and at a N/P charge mol ratio of 3:1 for liposome/DNA. Under optimized conditions, the efficiency of M1 and M6 is greater than that of all the tested commercial liposomes DC-Chol and Lipofectamine2000, even in the presence of serum. The results indicated that M1 and M6 exhibited low cytotoxicity, good serum compatibility and efficient transfection performance, having the potential of being excellent non-viral vectors for gene delivery. PMID:27072908

  10. Solidification cracking in austenitic stainless steel welds

    Indian Academy of Sciences (India)

    V Shankar; T P S Gill; S L Mannan; S Sundaresan

    2003-06-01

    Solidification cracking is a significant problem during the welding of austenitic stainless steels, particularly in fully austenitic and stabilized compositions. Hot cracking in stainless steel welds is caused by low-melting eutectics containing impurities such as S, P and alloy elements such as Ti, Nb. The WRC-92 diagram can be used as a general guide to maintain a desirable solidification mode during welding. Nitrogen has complex effects on weld-metal microstructure and cracking. In stabilized stainless steels, Ti and Nb react with S, N and C to form low-melting eutectics. Nitrogen picked up during welding significantly enhances cracking, which is reduced by minimizing the ratio of Ti or Nb to that of C and N present. The metallurgical propensity to solidification cracking is determined by elemental segregation, which manifests itself as a brittleness temperature range or BTR, that can be determined using the varestraint test. Total crack length (TCL), used extensively in hot cracking assessment, exhibits greater variability due to extraneous factors as compared to BTR. In austenitic stainless steels, segregation plays an overwhelming role in determining cracking susceptibility.

  11. Transformation of anthracene on various cation-modified clay minerals.

    Science.gov (United States)

    Li, Li; Jia, Hanzhong; Li, Xiyou; Wang, Chuanyi

    2015-01-01

    In this study, anthracene was employed as a probe to explore the potential catalytic effect of clay minerals in soil environment. Clay minerals saturated with various exchangeable cations were tested. The rate of anthracene transformation follows the order: Fe-smectite > Cu-smectite > Al-smectite ≈ Ca-smectite ≈ Mg-smectite ≈ Na-smectite. This suggests that transition-metal ions such as Fe(III) play an important role in anthracene transformation. Among Fe(III)-saturated clays, Fe(III)-smectite exhibits the highest catalytic activity followed by Fe(III)-illite, Fe(III)-pyrophyllite, and Fe(III)-kaolinite, which is in agreement with the interlayer Fe(III) content. Moreover, effects by two common environmental factors, pH and relative humidity (RH), were evaluated. With an increase in pH or RH, the rate of anthracene transformation decreases rapidly at first and then is leveled off. GC-MS analysis identifies that the final product of anthracene transformation is 9,10-anthraquinone, a more bioavailable molecule compared to anthracene. The transformation process mainly involves cation-π bonding, electron transfer leading to cation radical, and further oxidation by chemisorbed O2. The present work provides valuable insights into the abiotic transformation and the fate of PAHs in the soil environment and the development of contaminated land remediation technologies.

  12. Synthetic crystalline calcium silicate hydrate (I): cation exchange and caesium selectivity

    International Nuclear Information System (INIS)

    Solid crystalline calcium silicate hydrate (I) synthesized from equimolar amounts of Ca and Si under hydrothermal conditions at 120 oC shows cation exchange properties towards divalent metal cations such as Ni, Cu, Cd, or Hg. It also exhibits caesium selectivity in the presence of Na+. The exchange capacity and selectivity of the solid can be increased by 10 and 28 %, respectively, upon substitution of 0.01 mol of the Ca2+ in its structure by Na+. The ability of metal cation uptake by the solid was found to obey the order Ni2+ > Hg2+ > Cu2+ > Cd2+. The different affinities of calcium silicate hydrate (I) towards these ions can be used for their separation from solutions and also in nuclear waste treatment. The mechanism of the exchange reaction is discussed. (author)

  13. Localization versus delocalization in diamine radical cations

    DEFF Research Database (Denmark)

    Brouwer, A.M.; Wiering, P.G.; Zwier, J.M.;

    1997-01-01

    The optical absorption spectrum of the radical cation of 1,4-diphenylpiperazine 2a shows a strong transition in the near-IR, and only a weak band at 445 nm, in the region where aniline radical cations normally absorb strongly. This indicates that the charge and spin are delocalized over the two...

  14. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  15. Controlling potassium selectivity and proton blocking in a hybrid biological/solid-state polymer nanoporous membrane

    Science.gov (United States)

    Balme, Sébastien; Picaud, Fabien; Kraszewski, Sebastian; Déjardin, Philippe; Janot, Jean Marc; Lepoitevin, Mathilde; Capomanes, Jhon; Ramseyer, Christophe; Henn, François

    2013-04-01

    Specific separations of protons and cations are usually performed by electromembrane processes, which require external electric energy. An easier process would be using a membrane able to separate both entities by passive diffusion. Presently, such synthetic nanoporous membranes do not exist. Here, we report the production of a robust hybrid biological/artificial solid-state membrane, which allows selective permeation of alkali metal cations without competing or concurrent permeation of protons. This membrane is simple to prepare and is based on the hydrophobic nature of the polymeric pore walls, and the confined gramicidin A molecules within. This work opens a new route for separation in the domain of nanobiofiltration, especially for tunable nanodevices based on differential ion conduction, with a fundamental understanding of the confinement mechanism.Specific separations of protons and cations are usually performed by electromembrane processes, which require external electric energy. An easier process would be using a membrane able to separate both entities by passive diffusion. Presently, such synthetic nanoporous membranes do not exist. Here, we report the production of a robust hybrid biological/artificial solid-state membrane, which allows selective permeation of alkali metal cations without competing or concurrent permeation of protons. This membrane is simple to prepare and is based on the hydrophobic nature of the polymeric pore walls, and the confined gramicidin A molecules within. This work opens a new route for separation in the domain of nanobiofiltration, especially for tunable nanodevices based on differential ion conduction, with a fundamental understanding of the confinement mechanism. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00564j

  16. [Development of metal ions analysis by ion chromatography].

    Science.gov (United States)

    Yu, Hong; Wang, Yuxin

    2007-05-01

    Analysis of metal ions by ion chromatography, including cation-exchange ion chromatography, anion-exchange ion chromatography and chelation ion chromatography, is reviewed. The cation-exchange ion chromatography is a main method for the determination of metal ions. Stationary phases in cation-exchange ion chromatography are strong acid cation exchanger (sulfonic) and weak acid cation exchanger (carboxylic). Alkali metal ions, alkaline earth metal ions, transition metal ions, rare earth metal ions, ammonium ions and amines can be analyzed by cation-exchange ion chromatography with a suitable detector. The anion-exchange ion chromatography is suitable for the separation and analysis of alkaline earth metal ions, transition metal ions and rare earth metal ions. The selectivity for analysis of metal ions with anion-exchange ion chromatography is good. Simultaneous determination of metal ions and inorganic anions can be achieved using anion-exchange ion chromatography. Chelation ion chromatography is suitable for the determination of trace metal ions in complex matrices. A total of 125 references are cited.

  17. Naked (C5Me5)(2)M cations (M = Sc, Ti, and V) and their fluoroarene complexes

    NARCIS (Netherlands)

    Bouwkamp, MW; Budzelaar, PHM; Gercama, J; Morales, ID; de Wolf, J; Meetsma, A; Troyanov, SI; Teuben, JH; Hessen, B; Budzelaar, Peter H.M.; Hierro Morales, Isabel Del; Troyanov, Sergei I.

    2005-01-01

    The ionic metallocene complexes [Cp*M-2][BPh4] (CP* = C5Me5) of the trivalent 3d metals Sc, Ti, and V were synthesized and structurally characterized. For M Sc, the anion interacts weakly with the metal center through one of the phenyl groups, but for M = Ti and V, the cations are naked. They each c

  18. Cationic lipid membranes-specific interactions with counter-ions

    International Nuclear Information System (INIS)

    Lipids bearing net electric charges in their hydrophilic headgroups are ubiquitous in biological membranes. Recently, the interest in cationic lipids has surged because of their potential as non-viral transfection vectors. In order to utilize cationic lipids in transfer of nucleic acids and to elucidate the role of charged lipids in cellular membranes in general, their complex interactions within the membrane and with the molecules in the surrounding media need to be thoroughly characterized. Yet, even interactions between monovalent counter-ions and charged lipids are inadequately understood. We studied the interactions of the cationic gemini surfactant (2R,3R)-2,3-dimethoxy-1,4- bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (RR-1) with chloride, bromide, fluoride, and iodide as counter-ions by differential scanning calorimetry and Langmuir balance. Chloride interacts avidly with RR-1, efficiently condensing the monolayer, decreasing the collapse pressure, and elevating the main transition temperature. With bromide and iodide clearly different behaviour was observed, indicating specific interactions between RR-1 and these counter-ions. Moreover, with fluoride as a counter-ion and in pure water identical results were obtained, demonstrating inefficient electrostatic screening of the headgroups of RR-1 and suggesting fluoride being depleted on the surface of RR-1 membranes

  19. Cationic lipid membranes-specific interactions with counter-ions

    Energy Technology Data Exchange (ETDEWEB)

    Ryhaenen, Samppa J; Saeily, V Matti J; Kinnunen, Paavo K J [Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine, Biomedicum, University of Helsinki, PO Box 63 (Haartmaninkatu 8), Helsinki FIN-00014 (Finland)

    2006-07-19

    Lipids bearing net electric charges in their hydrophilic headgroups are ubiquitous in biological membranes. Recently, the interest in cationic lipids has surged because of their potential as non-viral transfection vectors. In order to utilize cationic lipids in transfer of nucleic acids and to elucidate the role of charged lipids in cellular membranes in general, their complex interactions within the membrane and with the molecules in the surrounding media need to be thoroughly characterized. Yet, even interactions between monovalent counter-ions and charged lipids are inadequately understood. We studied the interactions of the cationic gemini surfactant (2R,3R)-2,3-dimethoxy-1,4- bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (RR-1) with chloride, bromide, fluoride, and iodide as counter-ions by differential scanning calorimetry and Langmuir balance. Chloride interacts avidly with RR-1, efficiently condensing the monolayer, decreasing the collapse pressure, and elevating the main transition temperature. With bromide and iodide clearly different behaviour was observed, indicating specific interactions between RR-1 and these counter-ions. Moreover, with fluoride as a counter-ion and in pure water identical results were obtained, demonstrating inefficient electrostatic screening of the headgroups of RR-1 and suggesting fluoride being depleted on the surface of RR-1 membranes.

  20. Calix[4]arene Polyaza Derivatives: Novel Effective Neutral Receptors for Cations and (a)-Amino Acids

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Introduction Calixarenes are one of the most important supramolecular building blocks, which can be modified by introducing different functional and/or structrual groups to create a specific interaction between the host and the target molecules, such as metal cations and small organic molecules[1,2]. In particular, the recognition of amino acids is an interesting theme in biomimetic chemistry[3].

  1. Assessment of the biological effects of welding fumes emitted from metal inert gas welding processes of aluminium and zinc-plated materials in humans.

    Science.gov (United States)

    Hartmann, L; Bauer, M; Bertram, J; Gube, M; Lenz, K; Reisgen, U; Schettgen, T; Kraus, T; Brand, P

    2014-03-01

    The aim of this study was to investigate biological effects and potential health risks due to two different metal-inert-gas (MIG) welding fumes (MIG welding of aluminium and MIG soldering of zinc coated steel) in healthy humans. In a threefold cross-over design study 12 male subjects were exposed to three different exposure scenarios. Exposures were performed under controlled conditions in the Aachener Workplace Simulation Laboratory (AWSL). On three different days the subjects were either exposed to filtered ambient air, to welding fumes from MIG welding of aluminium, or to fumes from MIG soldering of zinc coated materials. Exposure was performed for 6 h and the average fume concentration was 2.5 mg m(-3). Before, directly after, 1 day after, and 7 days after exposure spirometric and impulse oscillometric measurements were performed, exhaled breath condensate (EBC) was collected and blood samples were taken and analyzed for inflammatory markers. During MIG welding of aluminium high ozone concentrations (up to 250 μg m(-3)) were observed, whereas ozone was negligible for MIG soldering. For MIG soldering, concentrations of high-sensitivity CRP (hsCRP) and factor VIII were significantly increased but remained mostly within the normal range. The concentration of neutrophils increased in tendency. For MIG welding of aluminium, the lung function showed significant decreases in Peak Expiratory Flow (PEF) and Mean Expiratory Flow at 75% vital capacity (MEF 75) 7 days after exposure. The concentration of ristocetin cofactor was increased. The observed increase of hsCRP during MIG-soldering can be understood as an indicator for asymptomatic systemic inflammation probably due to zinc (zinc concentration 1.5 mg m(-3)). The change in lung function observed after MIG welding of aluminium may be attributed to ozone inhalation, although the late response (7 days after exposure) is surprising.

  2. Electroanalysis of cationic species at membrane-carbon electrodes modified by polysaccharides. Bioaccumulation at microorganism-modified electrodes.

    Science.gov (United States)

    Lojou, E; Bianco, P

    2000-05-01

    Membrane-carbon electrodes modified with polysaccharides suspensions entrapped between a dialysis membrane and the carbon surface were used for electroanalysis of various cationic species. Cationic complexes of ruthenium and cobalt, metallic cations (Cu(2+), Fe(3+), UO(2)(2+)) as well as methylviologen were considered. By investigating various parameters (concentration of the suspension, pH) binding of the cations by the polysaccharides was demonstrated. Comparison of cations uptake by different kinds of polysaccharides such as alginic acid, polygalacturonic acid, pectin, dextran and agar was performed. This study has been extended to natural biomaterials, alga and lichen, which are known to contain polysaccharides. The interest of the membrane-electrode strategy is described.

  3. Nanoscale cation motion in TaOx, HfOx and TiOx memristive systems

    Science.gov (United States)

    Wedig, Anja; Luebben, Michael; Cho, Deok-Yong; Moors, Marco; Skaja, Katharina; Rana, Vikas; Hasegawa, Tsuyoshi; Adepalli, Kiran K.; Yildiz, Bilge; Waser, Rainer; Valov, Ilia

    2016-01-01

    A detailed understanding of the resistive switching mechanisms that operate in redox-based resistive random-access memories (ReRAM) is key to controlling these memristive devices and formulating appropriate design rules. Based on distinct fundamental switching mechanisms, two types of ReRAM have emerged: electrochemical metallization memories, in which the mobile species is thought to be metal cations, and valence change memories, in which the mobile species is thought to be oxygen anions (or positively charged oxygen vacancies). Here we show, using scanning tunnelling microscopy and supported by potentiodynamic current-voltage measurements, that in three typical valence change memory materials (TaOx, HfOx and TiOx) the host metal cations are mobile in films of 2 nm thickness. The cations can form metallic filaments and participate in the resistive switching process, illustrating that there is a bridge between the electrochemical metallization mechanism and the valence change mechanism. Reset/Set operations are, we suggest, driven by oxidation (passivation) and reduction reactions. For the Ta/Ta2O5 system, a rutile-type TaO2 film is believed to mediate switching, and we show that devices can be switched from a valence change mode to an electrochemical metallization mode by introducing an intermediate layer of amorphous carbon.

  4. Layered Double Hydroxides: Proposal of a One-Layer Cation-Ordered Structure Model of Monoclinic Symmetry.

    Science.gov (United States)

    Jayanthi, K; Nagendran, Supreeth; Kamath, P Vishnu

    2015-09-01

    Layered double hydroxides are obtained by partial isomorphous substitution of divalent metal ions by trivalent metal ions in the structure of mineral brucite, Mg(OH)2. The widely reported three-layer polytype of rhombohedral symmetry, designated as polytype 3R1, is actually a one-layer polytype of monoclinic symmetry (space group C2/m, a = 5.401 Å, b = 9.355 Å, c = 11.02 Å, β = 98.89°). This structure has a cation-ordered metal hydroxide layer defined by a supercell a = √3 × a0; b = 3 × a0 (a0 = cell parameter of the cation-disordered rhombohedral cell). Successive layers are translated by (1/3, 0, 1) relative to one another. When successive metal hydroxide layers are translated by (2/3, 0, 1) relative to one another, the resultant crystal, also of monoclinic symmetry, generates a powder pattern corresponding to the polytype hitherto designated as 3R2. This structure model not only removes all the anomalies intrinsic to the widely accepted cation-disordered structure but also abides by Pauling's rule that forbids trivalent cations from occupying neighboring sites and suggests that it is unnecessary to invoke rhombohedral symmetry when the metal hydroxide layer is cation ordered. These results have profound implications for the correct description of polytypism in this family of layered compounds. PMID:26267263

  5. High cation transport polymer electrolyte

    Science.gov (United States)

    Gerald, II, Rex E.; Rathke, Jerome W.; Klingler, Robert J.

    2007-06-05

    A solid state ion conducting electrolyte and a battery incorporating same. The electrolyte includes a polymer matrix with an alkali metal salt dissolved therein, the salt having an anion with a long or branched chain having not less than 5 carbon or silicon atoms therein. The polymer is preferably a polyether and the salt anion is preferably an alkyl or silyl moiety of from 5 to about 150 carbon/silicon atoms.

  6. The QUASIMENE Inter-laboratory Performance Study: trace metals in sediments and biological tissues; Partecipazione della sezione AMB-TEIN-CHIM a programmi di intercalibrazione in ambito nazionale ed europeo

    Energy Technology Data Exchange (ETDEWEB)

    Cremisini, C.; Galletti, M.; Gragnani, R. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1998-12-01

    Between 1993 and 1996 the European Union supported the development of a Quality Assurance programme of Information in Marine Environmental Monitoring in Europe (QUASIMEME). The aim of the programme was to improve and control the quality of marine environmental information through inter-laboratory studies on nutrients in sea water, chloro biphenyls and trace metals in sediments and biological tissue. This paper describes the participation of ENEA laboratory (AMB/TEIN/CHIM) to QUASIMEME-Programme for trace metals in sediments and biological tissues. [Italiano] Nel triennio 1993-1996 la Comunita` Europea ha supportato lo sviluppo del Programma QUASIMEME (Quality Assurance of Information in Marine Environmental Monitoring in Europe). L`obiettivo prioritario e` stato il controllo e il miglioramento della qualita` delle informazioni relative all`ambiente marino. Cio` e` stato realizzato mediante una serie di esercizi d`intercalibrazione tra circa 80 laboratori, sparsi in tutta Europa, relativamente a: nutrienti nell`acqua di mare, policlorobifenili e metalli nei sedimenti e nei tessuti biologici. In questo lavoro viene descritta la partecipazione del laboratorio ENEA (AMB/TEIN/CHIM) a tale Programma per la parte relativa alla determinazione dei metalli in traccia nei sedimenti e nei tessuti biologici.

  7. 非水毛细管电泳分离碱金属、碱土金属和铵离子的机理研究%Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    刘红霞; 宋鹃梅; 张书胜; MACKA Miroslav; HADDAD Paul R

    2004-01-01

    Capillary electrophoresis ( CE ) has rapidly gained great interests among researchers in many different fields. One of these areas is the separation of small ions such as inorganic cations, anions, and low Mr organic molecules However, as the separation of ions

  8. Cationic ruthenium alkylidene catalysts bearing phosphine ligands

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2016-01-01

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bear-ing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions pro-vided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported...

  9. The 6-amino-6-methyl-1,4-diazepine group as an ancillary ligand framework for neutral and cationic scandium and yttrium alkyls

    NARCIS (Netherlands)

    Ge, Shaozhong; Bambirra, Sergio; Meetsma, Auke; Hessen, Bart

    2006-01-01

    The 6-amino-6-methyl-1,4-diazepine framework is a readily available neutral 6-electron ligand moiety, suitable to support cationic group 3 metal alkyl catalysts; it also provides convenient access to tri- and tetradentate monoanionic ligand derivatives.

  10. Methods of making metal oxide nanostructures and methods of controlling morphology of same

    Science.gov (United States)

    Wong, Stanislaus S; Hongjun, Zhou

    2012-11-27

    The present invention includes a method of producing a crystalline metal oxide nanostructure. The method comprises providing a metal salt solution and providing a basic solution; placing a porous membrane between the metal salt solution and the basic solution, wherein metal cations of the metal salt solution and hydroxide ions of the basic solution react, thereby producing a crystalline metal oxide nanostructure.

  11. Types of cationic complexes based on oxocentred tetrahedra [OM4] in the crystal structures of inorganic compounds

    International Nuclear Information System (INIS)

    The crystal structures of inorganic compounds comprising cationic complexes containing oxygen atoms coordinated tetrahedrally to metal atoms, or oxocentred groups [OM4], are considered. The linking of the [OM4] tetrahedra in the structures has been analysed and cationic complexes of different structures have been identified. The rules governing the linking of the [OM4] tetrahedra have been formulated and the cationic complexes have been subjected to a detailed systematic treatment on their basis. Data on the statistics of the bond lengths and bond angles in the [OM4] tetrahedra are presented. The bibliography includes 317 references.

  12. Cation charge dependence of the forces driving DNA assembly.

    Science.gov (United States)

    DeRouchey, Jason; Parsegian, V Adrian; Rau, Donald C

    2010-10-20

    Understanding the strength and specificity of interactions among biologically important macromolecules that control cellular functions requires quantitative knowledge of intermolecular forces. Controlled DNA condensation and assembly are particularly critical for biology, with separate repulsive and attractive intermolecular forces determining the extent of DNA compaction. How these forces depend on the charge of the condensing ion has not been determined, but such knowledge is fundamental for understanding the basis of DNA-DNA interactions. Here, we measure DNA force-distance curves for a homologous set of arginine peptides. All forces are well fit as the sum of two exponentials with 2.4- and 4.8-Å decay lengths. The shorter-decay-length force is always repulsive, with an amplitude that varies slightly with length or charge. The longer-decay-length force varies strongly with cation charge, changing from repulsion with Arg¹ to attraction with Arg². Force curves for a series of homologous polyamines and the heterogeneous protein protamine are quite similar, demonstrating the universality of these forces for DNA assembly. Repulsive amplitudes of the shorter-decay-length force are species-dependent but nearly independent of charge within each species. A striking observation was that the attractive force amplitudes for all samples collapse to a single curve, varying linearly with the inverse of the cation charge. PMID:20959102

  13. Cation locations and dislocations in zeolites

    Science.gov (United States)

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  14. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  15. Cations and activated sludge floc structure

    OpenAIRE

    Park, Chul

    2002-01-01

    This research was designed to investigate the effect of cations on activated sludge characteristics and also to determine their influence on digestion performance. For this purpose, cations in solution and in floc were evaluated along with various activated sludge characteristics and the collected waste activated sludge underwent both anaerobic and aerobic digestion. It was found that large amounts of biopolymer (protein + polysaccharide) remained in the effluent of WWTP that received high in...

  16. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  17. Silica-based cationic bilayers as immunoadjuvants

    OpenAIRE

    Carmona-Ribeiro Ana M; da Costa Maria; Faquim-Mauro Eliana; Santana Mariana RA; Lincopan Nilton

    2009-01-01

    Abstract Background Silica particles cationized by dioctadecyldimethylammonium bromide (DODAB) bilayer were previously described. This work shows the efficiency of these particulates for antigen adsorption and presentation to the immune system and proves the concept that silica-based cationic bilayers exhibit better performance than alum regarding colloid stability and cellular immune responses for vaccine design. Results Firstly, the silica/DODAB assembly was characterized at 1 mM NaCl, pH 6...

  18. Efficient luminescent solar cells based on tailored mixed-cation perovskites

    OpenAIRE

    Bi, Dongqin; Tress, Wolfgang; Dar, M. Ibrahim; Gao, Peng; Luo, Jingshan; Renevier, Clémentine; Schenk, Kurt; Abate, Antonio; Giordano, Fabrizio; Correa Baena, Juan-Pablo; Decoppet, Jean-David; Zakeeruddin, Shaik Mohammed; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Hagfeldt, Anders

    2016-01-01

    We report on a new metal halide perovskite photovoltaic cell that exhibits both very high solar-to-electric power-conversion efficiency and intense electroluminescence. We produce the perovskite films in a single step from a solution containing a mixture of FAI, PbI2, MABr, and PbBr2 (where FA stands for formamidinium cations and MA stands for methylammonium cations). Using mesoporous TiO2 and Spiro-OMeTAD as electron- and hole-specific contacts, respectively, we fabricate perovskite solar ce...

  19. Microwaves spark emission spectroscopy for the analysis of cations: A simple form of atomic emission spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Zahid Hussain; Khalid Mohammed Khan; Khadim Hussain; Sadam Hussain; Shahnaz Perveen

    2011-01-01

    A novel method for the cation analysis was investigated. The analysis is based on the sparking of the salts of metals in a microwave oven after placing in a graphite cell. The graphite cell absorbs microwaves and produces high temperature which converts the salt into light emitting species. The colour of light was found to dependent on the nature of cation, however, the intensity of the emitted light was found to be depending upon the form and shape of the graphite assembly in addition to the concentration of the salt. This communication presents explanation for all these observations and for the systematic and quantitative analysis using microwave spark emission technique.

  20. Selective Gold Recovery and Catalysis in a Highly Flexible Methionine-Decorated Metal-Organic Framework.

    Science.gov (United States)

    Mon, Marta; Ferrando-Soria, Jesús; Grancha, Thais; Fortea-Pérez, Francisco R; Gascon, Jorge; Leyva-Pérez, Antonio; Armentano, Donatella; Pardo, Emilio

    2016-06-29

    A novel chiral 3D bioMOF exhibiting functional channels with thio-alkyl chains derived from the natural amino acid l-methionine (1) has been rationally prepared. The well-known strong affinity of gold for sulfur derivatives, together with the extremely high flexibility of the thioether "arms" decorating the channels, account for a selective capture of gold(III) and gold(I) salts in the presence of other metal cations typically found in electronic wastes. The X-ray single-crystal structures of the different gold adsorbates Au(III)@1 and Au(I)@1 suggest that the selective metal capture occurs in a metal ion recognition process somehow mimicking what happens in biological systems and protein receptors. Both Au(III)@1 and Au(I)@1 display high activity as heterogeneous catalyst for the hydroalkoxylation of alkynes, further expanding the application of these novel hybrid materials. PMID:27295383

  1. Synthesis and characterization of some metal complexes derived from azo compound of 4,4‧-methylenedianiline and antipyrine: Evaluation of their biological activity on some land snail species

    Science.gov (United States)

    AbouEl-Enein, Saeyda A.; Emam, Sanaa M.; Polis, Magdy W.; Emara, Esam M.

    2015-11-01

    A novel series of metal complexes of the azo dye; bis-(1,5-dimethyl-4-[(E)-(3-methylphenyl)diazenyl]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) derived from 4,4‧-methylenedianiline and antipyrine was synthesized and characterized by different spectral, thermal and analytical methods. The tetradentate ligand reacts with the metal ions as a half unit. All complexes display an octahedral geometry, except Pd(II) complex (7) which has a square planar one. The thermal studies reveal that the complexes have higher thermal stability comparable with that of the free ligand. The activation thermodynamic parameters, such as activation energy (E*), enthalpy of activation (ΔH*), entropy of activation (ΔS*) and Gibbs free energy (ΔG*) have been calculated using DTG curves. The ESR spectra of the solid Cu(II) complexes showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The biological activities of the ligand, as well as its metal complexes have been tested in vitro against two land snail species; Eobania vermiculata and Monacha obstructa. The results show that all the tested compounds have significant biological activities against the two tested land snail species with different sensitivity levels.

  2. Nanochemistry of metals

    Science.gov (United States)

    Sergeev, Gleb B.

    2001-10-01

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

  3. Structural Insights into Divalent Cation Modulations of ATP-Gated P2X Receptor Channels.

    Science.gov (United States)

    Kasuya, Go; Fujiwara, Yuichiro; Takemoto, Mizuki; Dohmae, Naoshi; Nakada-Nakura, Yoshiko; Ishitani, Ryuichiro; Hattori, Motoyuki; Nureki, Osamu

    2016-02-01

    P2X receptors are trimeric ATP-gated cation channels involved in physiological processes ranging widely from neurotransmission to pain and taste signal transduction. The modulation of the channel gating, including that by divalent cations, contributes to these diverse physiological functions of P2X receptors. Here, we report the crystal structure of an invertebrate P2X receptor from the Gulf Coast tick Amblyomma maculatum in the presence of ATP and Zn(2+) ion, together with electrophysiological and computational analyses. The structure revealed two distinct metal binding sites, M1 and M2, in the extracellular region. The M1 site, located at the trimer interface, is responsible for Zn(2+) potentiation by facilitating the structural change of the extracellular domain for pore opening. In contrast, the M2 site, coupled with the ATP binding site, might contribute to regulation by Mg(2+). Overall, our work provides structural insights into the divalent cation modulations of P2X receptors. PMID:26804916

  4. Study of the chemical interactions of actinide cations in solution at macroscopic concentrations

    International Nuclear Information System (INIS)

    The aim of this work was to study the interactions of pentavalent neptunium in dodecane-diluted tributyl phosphate with other metallic cations, especially uranium VI and ruthenium present in reprocessing solutions. Pentavalent neptunium on its own was shown to exist in several forms complexed by water and TBP and also to dimerise. In the complex it forms with uranium VI the interaction via the neptunyl oxygen is considerably enhanced in organic solution. Dibutyl phosphoric acid strengthens the interaction between neptunium and uranium. The Np V-ruthenium interaction reveals the existence of a new cation-cation complex; the process takes place in two successive stage and leads to the formation, reinforced and accelerated by HDBP, of a highly to the formation, reinforced and accelerated by HDBP, of a highly stable complex. These results contribute towards a better knowledge of the behaviour of neptunium in the reprocessing operation

  5. Changes in the ecological and biological properties of ordinary chernozems polluted by heavy metals of the second hazard class (Mo, Co, Cr, and Ni)

    Science.gov (United States)

    Kolesnikov, S. I.; Evreinova, A. V.; Kazeev, K. Sh.; Val'Kov, V. F.

    2009-08-01

    The pollution of ordinary chernozems by heavy metals of the second hazard class (Mo, Co, Cr, and Ni) results in a decrease in the numbers of saprotrophic bacteria and fungi and bacteria of the Azotobacter genus; the catalase and invertase activities and the rates of the cellulose and urea decomposition also decrease. The soil phytotoxicity becomes higher. With respect to their ecological hazard, the studied heavy metals may be arranged into the following sequence: Cr > Co ≥ Ni > Mo.

  6. Porous, rigid metal(III)-carboxylate metal-organic frameworks for the delivery of nitric oxide

    Science.gov (United States)

    Eubank, Jarrod F.; Wheatley, Paul S.; Lebars, Gaëlle; McKinlay, Alistair C.; Leclerc, Hervé; Horcajada, Patricia; Daturi, Marco; Vimont, Alexandre; Morris, Russell E.; Serre, Christian

    2014-12-01

    The room temperature sorption properties of the biological gas nitric oxide (NO) have been investigated on the highly porous and rigid iron or chromium carboxylate based metal-organic frameworks Material Institut Lavoisier (MIL)-100(Fe or Cr) and MIL-127(Fe). In all cases, a significant amount of NO is chemisorbed at 298 K with a loading capacity that depends both on the nature of the metal cation, the structure and the presence of additional iron(II) Lewis acid sites. In a second step, the release of NO triggered by wet nitrogen gas has been studied by chemiluminescence and indicates that only a partial release of NO occurs as well as a prolonged delivery at the biological level. Finally, an in situ infrared spectroscopy study confirms not only the coordination of NO over the Lewis acid sites and the stronger binding of NO on the additional iron(II) sites, providing further insights over the partial release of NO only in the presence of water at room temperature.

  7. Porous, rigid metal(III-carboxylate metal-organic frameworks for the delivery of nitric oxide

    Directory of Open Access Journals (Sweden)

    Jarrod F. Eubank

    2014-12-01

    Full Text Available The room temperature sorption properties of the biological gas nitric oxide (NO have been investigated on the highly porous and rigid iron or chromium carboxylate based metal-organic frameworks Material Institut Lavoisier (MIL-100(Fe or Cr and MIL-127(Fe. In all cases, a significant amount of NO is chemisorbed at 298 K with a loading capacity that depends both on the nature of the metal cation, the structure and the presence of additional iron(II Lewis acid sites. In a second step, the release of NO triggered by wet nitrogen gas has been studied by chemiluminescence and indicates that only a partial release of NO occurs as well as a prolonged delivery at the biological level. Finally, an in situ infrared spectroscopy study confirms not only the coordination of NO over the Lewis acid sites and the stronger binding of NO on the additional iron(II sites, providing further insights over the partial release of NO only in the presence of water at room temperature.

  8. Biofilm susceptibility to metal toxicity.

    Science.gov (United States)

    Harrison, Joe J; Ceri, Howard; Stremick, Carol A; Turner, Raymond J

    2004-12-01

    This study compared bacterial biofilm and planktonic cell susceptibility to metal toxicity by evaluating the minimum inhibitory concentration (MIC), the planktonic minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) using the MBEC device. In total, 17 metal cations and oxyanions, chosen to represent groups VIB to VIA of the periodic table, were each tested on biofilm and planktonic cultures of Escherichia coli JM109, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. In contrast to control antibiotic assays, where biofilm cultures were 2 to 64 times less susceptible to killing than logarithmically growing planktonic bacteria, metal compounds killed planktonic and biofilm cultures at the same concentration in the vast majority of combinations. Our data indicate that, under the conditions reported, growth in a biofilm does not provide resistance to bacteria against killing by metal cations or oxyanions.

  9. Forging Colloidal Nanostructures via Cation Exchange Reactions

    Science.gov (United States)

    2016-01-01

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  10. Treatment of drinking water residuals: comparing sedimentation and dissolved air flotation performance with optimal cation ratios.

    Science.gov (United States)

    Bourgeois, J C; Walsh, M E; Gagnon, G A

    2004-03-01

    Spent filter backwash water (SFBW) and clarifier sludge generally comprise the majority of the waste residual volume generated and in relative terms, these can be collectively referred to as combined filter backwash water (CFBW). CFBW is essentially a low-solids wastewater with metal hydroxide flocs that are typically light and slow to settle. This study evaluates the impact of adding calcium and magnesium carbonates to CFBW in terms of assessing the impacts on the sedimentation and DAF separation processes. Representative CFBW samples were collected from two surface water treatment plants (WTP): Lake Major WTP (Dartmouth, Nova Scotia, Canada) and Victoria Park WTP (Truro, Nova Scotia, Canada). Bench-scale results indicated that improvements in the CFBW settled water quality could be achieved through the addition of the divalent cations, thereby adjusting the monovalent to divalent (M:D) ratios of the wastewater. In general, the DAF process required slightly higher M:D ratios than the sedimentation process. The optimum M:D ratios for DAF and sedimentation were determined to be 1:1 and 0.33:1, respectively. It was concluded that the optimisation of the cation balance between monovalent cations (e.g., Na(+), K(+)) and added divalent cations (i.e., Ca(2+), Mg(2+)) aided in the settling mechanism through charge neutralisation-precipitation. The increase in divalent cation concentrations within the waste residual stream promoted destabilisation of the negatively charged colour molecules within the CFBW, thereby causing the colloidal content to become more hydrophobic. PMID:14975650

  11. DFT and MP2 study of the interaction between corannulene and alkali cations.

    Science.gov (United States)

    Rellán-Piñeiro, Marcos; Rodríguez-Otero, Jesús; Cabaleiro-Lago, Enrique M; Josa, Daniela

    2013-05-01

    Corannulene is an unsaturated hydrocarbon composed of fused rings, with one central five-membered ring and five peripheral six-membered rings. Its structure can be considered as a portion of C60. Corannulene is a curved π surface, but unlike C60, it has two accessible different faces: one concave (inside) and one convex (outside). In this work, computational modeling of the binding between alkali metal cations (Li(+), Na(+), and K(+)) and corannulene has been performed at the DFT and MP2 levels. Different corannulene···M(+) complexes have been studied and the transition states interconnecting local minima were located. The alkali cations can be bound to a five or six membered ring in both faces. At the DFT level, binding to the convex face (outside) is favored relative to the concave face for the three alkali cations studied, as it was previously published. This out preference was found to decrease as cation size increases. At the MP2 level, although a similar trend is found, some different conclusions related to the in/out preference were obtained. According to our results, migration of cations can take place on the convex or on the concave face. Also, there are two ways to transform a concave complex in a convex complex: migration across the edge of corannulene and bowl-to-bowl inversion.

  12. Interpnictogen cations: exploring new vistas in coordination chemistry.

    Science.gov (United States)

    Robertson, Alasdair P M; Gray, Paul A; Burford, Neil

    2014-06-10

    Pnictine derivatives can behave as both 2e(-) donors (Lewis bases) and 2e(-) acceptors (Lewis acids). As prototypical ligands in the coordination chemistry of transition metals, amines and phosphines also form complexes with p-block Lewis acids, including a variety of pnictogen-centered acceptors. The inherent Lewis acidity of pnictogen centers can be enhanced by the introduction of a cationic charge, and this feature has been exploited in recent years in the development of compounds resulting from coordinate Pn-Pn and Pn-Pn' interactions. These compounds offer the unusual opportunity for homoatomic coordinate bonding and the development of complexes that possess a lone pair of electrons at the acceptor center. This Review presents new directions in the systematic extension of coordination chemistry from the transition series into the p-block.

  13. Organic non-aqueous cation-based redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.

    2016-03-29

    The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

  14. Source of Lake Vostok Cations Constrained with Strontium Isotopes

    Science.gov (United States)

    Lyons, William; Welch, Kathleen; Priscu, John; Tranter, Martyn; Royston-Bishop, George

    2016-08-01

    Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources.

  15. Biosorption of cationic basic dye and cadmium by the novel biosorbent Bacillus catenulatus JB-022 strain.

    Science.gov (United States)

    Kim, Su Young; Jin, Mi Ra; Chung, Chang Ho; Yun, Yeoung-Sang; Jahng, Kwang Yeop; Yu, Kang-Yeol

    2015-04-01

    Biosorption of heavy metals and dyes is a promising technology that involves the removal of toxic metals from industrial wastes. The present study aims to screen the bacterial strains isolated from soils and polluted pond for their potential biosorption of both cationic dye and cadmium. Bacillus catenulatus JB-022 strain removed 58% and 66% of cationic basic blue 3 (BB3) and cadmium (Cd(II)) at the respective concentrations of 2000 mg/L and 150 mg/L. The biosorption equilibrium data were well fitted by the Langmuir adsorption isotherm, and the kinetic studies indicated that the biosorption followed the pseudo-second-order model. The biosorption kinetics showed that the equilibrium was reached within 10 min and 5 min for BB3 and Cd(II), respectively. According to the Langmuir model, the maximum uptakes of BB3 and Cd(II) by the JB-022 biomass were estimated to be 139.74 and 64.28 mg/g, respectively. To confirm the surface morphology and functional groups, field emission scanning electron microscope, energy-dispersive X-ray spectrometer, X-ray diffraction, and Fourier transform infrared spectroscopy analyses were carried out, and the results revealed that the biomass of JB-022 has carboxyl and phosphonate groups as potential surface functional groups capable of binding to cationic pollutants. In conclusion, B. catenulatus JB-022 is proposed as an excellent biosorbent with potentially important applications in removal of cationic pollutants from wastewaters.

  16. Metal sulfide and rare-earth phosphate nanostructures and methods of making same

    Science.gov (United States)

    Wong, Stanislaus; Zhang, Fen

    2014-05-13

    The present invention provides a method of producing a crystalline metal sulfide nanostructure. The metal is a transitional metal or a Group IV metal. In the method, a porous membrane is placed between a metal precursor solution and a sulfur precursor solution. The metal cations of the metal precursor solution and sulfur ions of the sulfur precursor solution react, thereby producing a crystalline metal sulfide nanostructure.

  17. Mixed cation effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.;

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural...... and topological features of these glasses and we use AFM to quantify the resistances associated with each deformation process under Vickers indentation. We demonstrate that the mixed cation effect manifests itself as a maximum in the amount of bonded tetrahedral units and as a minimum in liquid fragility index...

  18. Cation Effect on Copper Chemical Mechanical Polishing

    Institute of Scientific and Technical Information of China (English)

    WANG Liang-Yong; LIU Bo; SONG Zhi-Tang; FENG Song-Lin

    2009-01-01

    We examine the effect of cations in solutions containing benzotriazole (BTA) and H2O2 on copper chemical mechanical polishing (CMP). On the base of atomic force microscopy (AFM) and material removal rate (MRR) results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demon-strates the worst performance. These results reveal a mechanism that sma//molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential (OCP).

  19. Metal and nutrient dynamics in decomposing tree litter on a metal contaminated site

    International Nuclear Information System (INIS)

    In a forest on sandy, metal polluted soil, we examined effects of six tree species on litter decomposition rates and accompanied changes in metal (Cd, Zn) and nutrient (base cations, N, C) amounts. Decomposition dynamics were studied by means of a litterbag experiment lasting for 30 months. The decomposition peak occurred within the first year for all tree species, except for aspen. During litter decomposition, high metal litter types released part of their accumulated metals, whereas low metal litter types were characterized by a metal enrichment. Base cations, N and C were released from all litter types. Metal release from contaminated litter might involve risks for metal dispersion towards the soil. On the other hand, metal enrichment of uncontaminated litter may be ecologically relevant as it can be easily transported or serve as food source. - Highlights: • Litter decomposition peak occurred within the first year for all tree species, except for aspen. • Base cations, N and C were released from all litter types during decomposition. • Cd and Zn were released from the high metal litter types. • Low metal litter types were characterized by a net Cd and Zn enrichment. • Metal and nutrient releases were reflected in topsoil characteristics. - Litter decomposition rates, as well as enrichment and release dynamics of metals and nutrients in decomposing litter were divergent under the different tree species

  20. Cu and Zn adsorption to a heterogeneous natural sediment: Influence of leached cations and natural organic matter.

    Science.gov (United States)

    Fisher-Power, Leanne M; Cheng, Tao; Rastghalam, Zahra Sadat

    2016-02-01

    Adsorption of heavy metals by natural sediments has important implications to the fate and transport of contaminants in subsurface environments. Although the importance of major multivalent cations and dissolved organic matter (DOM) in heavy metal adsorption had been previously demonstrated, the leaching of major cations and DOM from sediments and its influence on heavy metal adsorption have not been fully examined. In this study, the concentrations of Ca, Mg, Al, Fe, and natural organic matter that leached from a natural sediment in Cu and Zn adsorption experiments were measured and used in surface complexation models to elucidate their effects on Cu and Zn adsorption. Experimental results showed that the leaching of cations and DOM was substantial and pH-dependent. The leached concentrations of Ca and Mg were reasonably simulated based on BaCl2 extractable Ca and Mg at pH adsorption at pH adsorption at pH 3-8. Due to varying affinity for DOM between Cu and Zn, DOM was found to decrease Cu adsorption at pH > 6 due to formation of Cu-DOM aqueous complexes, but increase Zn adsorption at pH 4-7 due to formation of aqueous complexes between DOM and major cations, which reduced competition from these cations against Zn for binding sites on the sediment.

  1. A novel cationic liposome formulation for efficient gene delivery via a pulmonary route

    Science.gov (United States)

    Li, Peng; Liu, Donghua; Sun, Xiaoli; Liu, Chunxi; Liu, Yongjun; Zhang, Na

    2011-06-01

    The clinical success of gene therapy for lung cancer is not only dependent on efficient gene carriers but also on a suitable delivery route. A pulmonary delivery route can directly deliver gene vectors to the lung which is more efficient than a systemic delivery route. For gene carriers, cationic liposomes have recently emerged as leading non-viral vectors in worldwide gene therapy clinical trials. However, cytotoxic effects or apoptosis are often observed which is mostly dependent on the cationic lipid used. Therefore, an efficient and safe cationic lipid, 6-lauroxyhexyl lysinate (LHLN), previously synthesized by our group was first used to prepare cationic liposomes. Physicochemical and biological properties of LHLN-liposomes were investigated. LHLN-liposome/DNA complexes showed positive surface charge, spherical morphology, a relatively narrow particle size distribution and strong DNA binding capability. Compared with Lipofectamine2000, the new cationic liposome formulation using LHLN exhibited not only lower cytotoxicity (P transfection efficiency in A549 and HepG2 lung cancer cells for in vitro tests. When administered by intratracheal instillation into rat lungs for in vivo evaluation, LHLN-liposome/DNA complexes exhibited higher pulmonary gene transfection efficiency than Lipofectamine2000/DNA complexes (P < 0.05). These results suggested that LHLN-liposomes may have great potential for efficient pulmonary gene delivery.

  2. A novel cationic liposome formulation for efficient gene delivery via a pulmonary route

    International Nuclear Information System (INIS)

    The clinical success of gene therapy for lung cancer is not only dependent on efficient gene carriers but also on a suitable delivery route. A pulmonary delivery route can directly deliver gene vectors to the lung which is more efficient than a systemic delivery route. For gene carriers, cationic liposomes have recently emerged as leading non-viral vectors in worldwide gene therapy clinical trials. However, cytotoxic effects or apoptosis are often observed which is mostly dependent on the cationic lipid used. Therefore, an efficient and safe cationic lipid, 6-lauroxyhexyl lysinate (LHLN), previously synthesized by our group was first used to prepare cationic liposomes. Physicochemical and biological properties of LHLN-liposomes were investigated. LHLN-liposome/DNA complexes showed positive surface charge, spherical morphology, a relatively narrow particle size distribution and strong DNA binding capability. Compared with Lipofectamine2000, the new cationic liposome formulation using LHLN exhibited not only lower cytotoxicity (P < 0.05) but also similar transfection efficiency in A549 and HepG2 lung cancer cells for in vitro tests. When administered by intratracheal instillation into rat lungs for in vivo evaluation, LHLN-liposome/DNA complexes exhibited higher pulmonary gene transfection efficiency than Lipofectamine2000/DNA complexes (P < 0.05). These results suggested that LHLN-liposomes may have great potential for efficient pulmonary gene delivery.

  3. High-throughput metal susceptibility testing of microbial biofilms

    Directory of Open Access Journals (Sweden)

    Turner Raymond J

    2005-10-01

    Full Text Available Abstract Background Microbial biofilms exist all over the natural world, a distribution that is paralleled by metal cations and oxyanions. Despite this reality, very few studies have examined how biofilms withstand exposure to these toxic compounds. This article describes a batch culture technique for biofilm and planktonic cell metal susceptibility testing using the MBEC assay. This device is compatible with standard 96-well microtiter plate technology. As part of this method, a two part, metal specific neutralization protocol is summarized. This procedure minimizes residual biological toxicity arising from the carry-over of metals from challenge to recovery media. Neutralization consists of treating cultures with a chemical compound known to react with or to chelate the metal. Treated cultures are plated onto rich agar to allow metal complexes to diffuse into the recovery medium while bacteria remain on top to recover. Two difficulties associated with metal susceptibility testing were the focus of two applications of this technique. First, assays were calibrated to allow comparisons of the susceptibility of different organisms to metals. Second, the effects of exposure time and growth medium composition on the susceptibility of E. coli JM109 biofilms to metals were investigated. Results This high-throughput method generated 96-statistically equivalent biofilms in a single device and thus allowed for comparative and combinatorial experiments of media, microbial strains, exposure times and metals. By adjusting growth conditions, it was possible to examine biofilms of different microorganisms that had similar cell densities. In one example, Pseudomonas aeruginosa ATCC 27853 was up to 80 times more resistant to heavy metalloid oxyanions than Escherichia coli TG1. Further, biofilms were up to 133 times more tolerant to tellurite (TeO32- than corresponding planktonic cultures. Regardless of the growth medium, the tolerance of biofilm and planktonic

  4. Synthesis and characterization of ligational behavior of curcumin drug towards some transition metal ions: Chelation effect on their thermal stability and biological activity

    Science.gov (United States)

    Refat, Moamen S.

    2013-03-01

    Complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with curcumin ligand as antitumor activity were synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV-Vis, IR, Raman, ESR, 1H-NMR spectroscopy, X-ray diffraction analysis of powdered samples and thermal analysis, and screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as a monobasic bidentate ligand towards the central metal ion with an oxygen's donor atoms sequence of both sbnd OH and Cdbnd O groups under keto-enol structure. From the microanalytical data, the stoichiometry of the complexes 1:2 (metal:ligand) was found. The ligand and their metal complexes were screened for antibacterial activity against Escherichia Coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa and fungicidal activity against Aspergillus flavus and Candida albicans.

  5. Biological Threats

    Science.gov (United States)

    ... Workplace Plans School Emergency Plans Main Content Biological Threats Biological agents are organisms or toxins that can ... for Disease Control and Prevention . Before a Biological Threat Unlike an explosion, a biological attack may or ...

  6. Rational Design of Methodology-Independent Metal Parameters Using a Nonbonded Dummy Model.

    Science.gov (United States)

    Jiang, Yang; Zhang, Haiyang; Tan, Tianwei

    2016-07-12

    A nonbonded dummy model for metal ions is highly imperative for the computation of complex biological systems with for instance multiple metal centers. Here we present nonbonded dummy parameters of 11 divalent metallic cations, namely, Mg(2+), V(2+), Cr(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Zn(2+), Cd(2+), Sn(2+), and Hg(2+), that are optimized to be compatible with three widely used water models (TIP3P, SPC/E, and TIP4P-EW). The three sets of metal parameters reproduce simultaneously the solvation free energies (ΔGsol), the ion-oxygen distance in the first solvation shell (IOD), and coordination numbers (CN) in explicit water with a relative error less than 1%. The main sources of errors to ΔGsol that arise from the boundary conditions and treatment of electrostatic interactions are corrected rationally, which ensures the independence of the proposed parameters on the methodology used in the calculation. This work will be of great value for the computational study of metal-containing biological systems. PMID:27182744

  7. Metal Mixture Modeling Evaluation project: 2. Comparison of four modeling approaches

    Science.gov (United States)

    Farley, Kevin J.; Meyer, Joe; Balistrieri, Laurie S.; DeSchamphelaere, Karl; Iwasaki, Yuichi; Janssen, Colin; Kamo, Masashi; Lofts, Steve; Mebane, Christopher A.; Naito, Wataru; Ryan, Adam C.; Santore, Robert C.; Tipping, Edward

    2015-01-01

    As part of the Metal Mixture Modeling Evaluation (MMME) project, models were developed by the National Institute of Advanced Industrial Science and Technology (Japan), the U.S. Geological Survey (USA), HDR⎪HydroQual, Inc. (USA), and the Centre for Ecology and Hydrology (UK) to address the effects of metal mixtures on biological responses of aquatic organisms. A comparison of the 4 models, as they were presented at the MMME Workshop in Brussels, Belgium (May 2012), is provided herein. Overall, the models were found to be similar in structure (free ion activities computed by WHAM; specific or non-specific binding of metals/cations in or on the organism; specification of metal potency factors and/or toxicity response functions to relate metal accumulation to biological response). Major differences in modeling approaches are attributed to various modeling assumptions (e.g., single versus multiple types of binding site on the organism) and specific calibration strategies that affected the selection of model parameters. The models provided a reasonable description of additive (or nearly additive) toxicity for a number of individual toxicity test results. Less-than-additive toxicity was more difficult to describe with the available models. Because of limitations in the available datasets and the strong inter-relationships among the model parameters (log KM values, potency factors, toxicity response parameters), further evaluation of specific model assumptions and calibration strategies is needed.

  8. Rational Design of Methodology-Independent Metal Parameters Using a Nonbonded Dummy Model.

    Science.gov (United States)

    Jiang, Yang; Zhang, Haiyang; Tan, Tianwei

    2016-07-12

    A nonbonded dummy model for metal ions is highly imperative for the computation of complex biological systems with for instance multiple metal centers. Here we present nonbonded dummy parameters of 11 divalent metallic cations, namely, Mg(2+), V(2+), Cr(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Zn(2+), Cd(2+), Sn(2+), and Hg(2+), that are optimized to be compatible with three widely used water models (TIP3P, SPC/E, and TIP4P-EW). The three sets of metal parameters reproduce simultaneously the solvation free energies (ΔGsol), the ion-oxygen distance in the first solvation shell (IOD), and coordination numbers (CN) in explicit water with a relative error less than 1%. The main sources of errors to ΔGsol that arise from the boundary conditions and treatment of electrostatic interactions are corrected rationally, which ensures the independence of the proposed parameters on the methodology used in the calculation. This work will be of great value for the computational study of metal-containing biological systems.

  9. Water adsorption on free cobalt cluster cations

    NARCIS (Netherlands)

    D.M. Kiawi; J.M. Bakker; J. Oomens; W.J. Buma; Z. Jamshidi; L. Visscher; L.B.F.M. Waters

    2015-01-01

    Cationic cobalt clusters complexed with water Con+-​H2O (n = 6-​20) are produced through laser ablation and investigated via IR multiple photon dissocn. (IR-​MPD) spectroscopy in the 200-​1700 cm-​1 spectral range. All spectra exhibit a resonance close to the 1595 cm-​1 frequency of the free water b

  10. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.;

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M alk...

  11. Resonance raman studies of phenylcyclopropane radical cations

    NARCIS (Netherlands)

    Godbout, J.T.; Zuilhof, H.; Heim, G.; Gould, I.R.; Goodman, J.L.; Dinnocenzo, J.P.; Myers Kelley, A.

    2000-01-01

    Resonance Raman spectra of the radical cations of phenylcyclopropane and trans-1-phenyl-2-methylcyclopropane are reported. A near-UV pump pulse excites a photosensitizer which oxidizes the species of interest, and a visible probe pulse delayed by 35 ns obtains the spectrum of the radical ion. The tr

  12. Anionic/cationic complexes in hair care.

    Science.gov (United States)

    O'Lenick, Tony

    2011-01-01

    The formulation of cosmetic products is always more complicated than studying the individual components in aqueous solution. This is because there are numerous interactions between the components, which make the formulation truly more than the sum of the parts. This article will look at interactions between anionic and cationic surfactants and offer insights into how to use these interactions advantageously in making formulations.

  13. Cation distribution in ferrites and its effects on the chemical dissolution behaviour

    International Nuclear Information System (INIS)

    Ferrites are formed on the steel surfaces as a protective corrosion oxide film on the heat transport surfaces in the water cooled nuclear reactors. These oxides film acts as a host to many neutron activated corrosion products (ACPs) leading to man-rem problem during the service maintenance. Understanding of chemical dissolution kinetics of these ferrites is important aspect in the development of decontamination process with aim of good decontamination factors. Ferrite shows a cation distribution as a function of parameter like metal ion substitution, crystallite size and temperature. Change in the cation distribution in ferrite can effect its dissolution process. The following three ferrites namely CoFe2O4/ZnFe2O4/MgFe2O4 were studied for its chemical dissolution behaviour as a function of the cation distribution. CoFe2O4, MgFe2O4 and ZnFe2O4 shows an inversion parameters of 0.95, 0.46 and 0.06 respectively. The above ferrites with different cation distribution were achieved by the thermal treatment. The variation of cation distribution in ferrite was monitored/characterised by the Raman spectroscopy. Chemical dissolution of these ferrites were carried out in NAC formulation. Dissolution process was monitored by the metal ion dissolution in the solution. Dissolution data was fitted to the following two models 'Shrinking sphere model' and 'Factual chain mechanism model' to elucidate the kinetic parameter. We tried to establish correlation between the cation distribution in the ferrite and the dissolution kinetics of ferrites. ZnFe2O4 ('δ'= ∼ 0.06) showed k80obs(Fe) = 1.250 x 10-3 min-1and ZnFe2O4 ('δ' = ∼ 0.30) showed k80obs(Fe) =2.295 x 10-3min-1, indicating ZnFe2O4 with high inversion parameter showed higher dissolution rate. Activation energy for the ZnFe2O4 ('δ'= ∼ 0.30) and ZnFe2O4 ('δ'= ∼ 0.06) in NAC formulation was 58.4 and 61.5 kJ mol-1 respectively. CoFe2O4 and MgFe2O4 also showed the

  14. Block of endplate channels by permeant cations in frog skeletal muscle

    OpenAIRE

    1981-01-01

    Motor endplates of frog semitendinosus muscles were studied under voltage clamp. Current fluctuations induced by iontophoretic application of acetylcholine were analyzed to give the elementary conductance, gamma , and mean open time, tau , of endplate channels. Total replacement of the external Na+ ion by several other metal ions and by many permeant organic cations changed both gamma and tau . Except with NH4+ ions, the gamma values with foreign test ions were all smaller than expected from ...

  15. Porous cationic polymers: the impact of counteranions and charges on CO2 capture and conversion.

    Science.gov (United States)

    Buyukcakir, Onur; Je, Sang Hyun; Choi, Dong Shin; Talapaneni, Siddulu Naiudu; Seo, Yongbeom; Jung, Yousung; Polychronopoulou, Kyriaki; Coskun, Ali

    2016-01-18

    Porous cationic polymers (PCPs) with surface areas up to 755 m(2) g(-1) bearing positively charged viologen units in their backbones and different counteranions have been prepared. We have demonstrated that by simply varying counteranions both gas sorption and catalytic properties of PCPs can be tuned for metal-free capture and conversion of CO2 into value-added products such as cyclic carbonates with excellent yields.

  16. Structural, spectral and biological studies of binuclear tetradentate metal complexes of N3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine.

    Science.gov (United States)

    Emara, Adel A A

    2010-09-15

    The binuclear Schiff base, H2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria (Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and (Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi (Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms. PMID:20627808

  17. Exploring the kinetic and thermodynamic aspects of four-electron electrochemical reactions: electrocatalysis of oxygen evolution by metal oxides and biological systems.

    Science.gov (United States)

    Wang, Vincent C-C

    2016-08-10

    Finding fundamental and general mechanisms for electrochemical reactions, such as the oxygen evolution reaction (OER) from water and reduction of CO2, plays vital roles in developing the desired electrocatalysts for facilitating solar fuel production. Recently, density functional theory (DFT) calculations have shown that there is a universal scaling relation of adsorption energy between key intermediate species, HO(ad) and HOO(ad), on the surface of metal oxides as OER electrocatalysts. In this paper, a kinetic and thermodynamic model for the four-electron electrochemical reaction based on previous OER mechanisms proposed by DFT calculations is developed to further investigate the electrocatalytic properties over a wide range of metal oxides and photosystem II. The OER activity of metal oxides (i.e. electrocatalytic current) calculated from the DFT-calculated equilibrium potentials with kinetic properties, such as the rate constants for interfacial electron transfer and catalytic turnover, can lead to a volcano-shaped trend that agrees with the results observed in experiments. In addition, the kinetic aspects of the impact on the electrocatalysts are evaluated. Finally, comparing the results of metal oxides and photosystem II, and fitting experimental voltammograms give further insights into kinetic and thermodynamic roles. Here, the general guidelines for designing OER electrocatalysts with unified kinetic and thermodynamic properties are presented. PMID:27460039

  18. Cationic lipids and cationic ligands induce DNA helix denaturation: detection of single stranded regions by KMnO4 probing.

    Science.gov (United States)

    Prasad, T K; Gopal, Vijaya; Rao, N Madhusudhana

    2003-09-25

    Cationic lipids and cationic polymers are widely used in gene delivery. Using 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) as a cationic lipid, we have investigated the stability of the DNA in DOTAP:DNA complexes by probing with potassium permanganate (KMnO4). Interestingly, thymidines followed by a purine showed higher susceptibility to cationic ligand-mediated melting. Similar studies performed with other water-soluble cationic ligands such as polylysine, protamine sulfate and polyethyleneimine also demonstrated melting of the DNA but with variations. Small cations such as spermine and spermidine and a cationic detergent, cetyl trimethylammonium bromide, also rendered the DNA susceptible to modification by KMnO4. The data presented here provide direct proof for melting of DNA upon interaction with cationic lipids. Structural changes subsequent to binding of cationic lipids/ligands to DNA may lead to instability and formation of DNA bubbles in double-stranded DNA.

  19. Synthesis, spectroscopic characterization, electrochemistry and biological evaluation of some binuclear transition metal complexes of bicompartmental ONO donor ligands containing benzo[b]thiophene moiety

    Science.gov (United States)

    Mahendra Raj, K.; Vivekanand, B.; Nagesh, G. Y.; Mruthyunjayaswamy, B. H. M.

    2014-02-01

    A series of new binucleating Cu(II), Co(II), Ni(II) and Zn(II) complexes of bicompartmental ligands with ONO donor were synthesized. The ligands were obtained by the condensation of 3-chloro-6-substituted benzo[b]thiophene-2-carbohydrazides and 4,6-diacetylresorcinol. The synthesized ligands and their complexes were characterized by elemental analysis and various spectroscopic techniques. Elemental analysis, IR, 1H NMR, ESI-mass, UV-Visible, TG-DTA, magnetic measurements, molar conductance and powder-XRD data has been used to elucidate their structures. The bonding sites are the oxygen atom of amide carbonyl, azomethine nitrogen and phenolic oxygen for ligands 1 and 2. The binuclear nature of the complexes was confirmed by ESR spectral data. TG-DTA studies for some complexes showed the presence of coordinated water molecules and the final product is the metal oxide. All the complexes were investigated for their electrochemical activity, only the Cu(II) complexes showed the redox property. Cu(II) complexes were square planar, whereas Co(II), Ni(II) and Zn(II) complexes were octahedral. Powder-XRD pattern have been studied in order to test the degree of crystallinity of the complexes and unit cell calculations were made. In order to evaluate the effect of antimicrobial activity of metal ions upon chelation, both the ligands and their metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The results showed that the metal complexes were found to be more active than free ligands. The DNA cleaving capacities of all the complexes were analyzed by agarose gel electrophoresis method against supercoiled plasmid DNA. Among the compounds tested for antioxidant capacity, ligand 1 displayed excellent activity than its metal complexes.

  20. Spectrophotometric Microdetermination of Thorium(IV) and Uranium(VI) with Chrome Azurol-S in Presence of Cationic Surfactant

    OpenAIRE

    Upase, A. B.; A. B. Zade; P. P. Kalbende

    2011-01-01

    Cationic surfactant, cetyldimethylethylammonium bromide (CDMEAB), sensitize the color reactions of Th(IV) and U(VI) with chrome azurol-S(CRAS). Formation of water soluble deeply colored ternary complexes of metal ions show large bathochromic shift. Same stoichiometric composition of ternary complexes with 1:2:4 molar ratio (M-CRAS-CDMEAB) have been observed for both the metal ions and are responsible for enhancement in molar absorptivities and sensitivities at shifted wavelength. The ternary ...

  1. Chemically modified polymeric resins for separation of cations, organic acids, and small polar moleculea by high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.B.

    1993-07-01

    This thesis is divided into 4 parts: a review, ion chromatography of metal cations on carboxylic resins, separation of hydrophilic organic acids and small polar compounds on macroporous resin columns, and use of eluent modifiers for liquid chromatographic separation of carboxylic acids using conductivity detection.

  2. Monitoring of total metal concentration in sludge samples: Case study for the mechanical–biological wastewater treatment plant in Velika Gorica, Croatia

    International Nuclear Information System (INIS)

    In this paper, monitoring of total metal concentration in sludge samples from wastewater treatment process is elaborated. The presented results summarize the analyses of sludge samples in a period from 2008 to 2012. Possible sources of pollutions are given. Primarily, waste solid samples were collected from different pretreatment steps: (A) coarse grid, (B) fine grid and (C) aerated sand grease grid. Samples of A and B followed a repeatable pattern in 2008 and 2010. According to the results from 2008, samples of C contained measurable concentration of the following metals (mg/kg dry matter): Zn (21), Ni (1.05) and Ba (14.9). Several types of sludge samples were analyzed: fresh raw sludge (PS; 6–12 hour old), the sludge from the digester for anaerobic sludge treatment (DS; 48–72 hour old), samples from lagoons where the sludge is temporarily deposited (DOS and DOSold; 30–120 days) and sludge samples from agricultural areas (AA; aged over 180 days). Additionally, samples of dehydrated sludge (DEHS and DEHSold; 90–180 days) were collected upon construction of equipment for sludge dehydration in 2011. An analysis of total metal concentrations for Cu, Zn, Cr, Pb, Ni, Hg, Cd, Ba, As, Se, Sb, Co, Mo, Fe and Mn was performed by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). The most recent results (year 2011) indicated a high concentration of heavy metals in PS samples, exceeding the MCLs (mg/kg dry matter): Cu (2122), Zn (5945), Hg (13.67) and Cd (6.29). In 2012 (until July), only a concentration of Cu exceeded MCL (928.75 and 1230.5 in DS and DEHS, respectively). A composition of sludge was variable through time, offering the limited possibility for future prediction. The sludge is being considered as a hazardous waste and a subject of discussion regarding disposal. - Highlights: ► Summarized 5-year monitoring data for heavy metals in sludge ► Partially determined sources of pollution by

  3. Cation-cation interactions, magnetic communication and reactivity of the pentavalent uraniumion [U(NR)2]+

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Liam P [Los Alamos National Laboratory; Schelter, Eric J [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Yang, Ping [Los Alamos National Laboratory; Gsula, Robyn L [NON LANL; Scott, Brian L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Kiplinger, Jacqueline L [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory

    2009-01-01

    The dimeric bis(imido) uranium complex [{l_brace}U(NtBu)2(I)(tBu2bpy){r_brace}2] (see picture; U green, N blue, I red) has cation-cation interactions between [U(NR)2]+ ions. This f1-f1 system also displays f orbital communication between uranium(V) centers at low temperatures, and can be oxidized to generate uranium(VI) bis(imido) complexes.

  4. Transition metal complexes of an isatinic quinolyl hydrazone

    Directory of Open Access Journals (Sweden)

    Seleem Hussein S

    2011-06-01

    Full Text Available Abstract Background The importance of the isatinic quinolyl hydrazones arises from incorporating the quinoline ring with the indole ring in the same compound. Quinoline ring has therapeutic and biological activities. On the other hand, isatin (1H-indole-2,3-dione and its derivatives exhibit a wide range of biological activities. Also, the indole ring occurs in Jasmine flowers and Orange blossoms. Recently, the physiological and biological activities of quinolyl hydrazones arise from their tendency to form metal chelates with transition metal ions. In this context, we have reported to isolate, characterize and study the biological activity of some transition metal complexes of an isatinic quinolyl hydrazone; 3-[2-(4-methyl quinolin-2-ylhydrazono] indolin-2-one. Results Mono- and binuclear as well as dimeric chelates were obtained from the reaction of a new isatinic quinolyl hydrazone with Fe(III, Co(II, Ni(II, Cu(II, VO(II and Pd(II ions. The ligand showed a variety of modes of bonding viz. (NNO2-, (NO- and (NO per each metal ion supporting its ambidentate and flexidentate characters. The mode of bonding and basicity of the ligand depend mainly on the type of the metal cation and its counter anion. All the obtained Pd(II- complexes have the preferable square planar geometry (D4h- symmetry and depend mainly on the mole ratio (M:L. Conclusion The effect of the type of the metal ion for the same anion (Cl- is obvious from either structural diversity of the isolated complexes (Oh, Td and D4h or the various modes of bonding. The isatinic hydrazone uses its lactim form in all complexes (Cl- except complex 5 (SO42- in which it uses its lactam form. The obtained Pd(II- complexes (dimeric, mono- and binuclear are affected by the mole ratio (M:L and have the square planar (D4h geometry. Also, the antimicrobial activity is highly influenced by the nature of the metal ion and the order for S. aureus bacteria is as follows: Nickel(II > Vanadyl(II > Cobalt

  5. Separation of traces of metal ions from sodium matrices

    Science.gov (United States)

    Korkisch, J.; Orlandini, K. A.

    1969-01-01

    Method for isolating metal ion traces from sodium matrices consists of two extractions and an ion exchange step. Extraction is accomplished by using 2-thenoyltrifluoracetone and dithizone followed by cation exchange.

  6. Effect of competing cations (Cu, Zn, Mn, Pb) adsorbed by natural zeolite

    OpenAIRE

    Zendelska, Afrodita; Golomeova, Mirjana

    2014-01-01

    The aim of this work was to investigate the influence of the presence of competing cations on the individual adsorption of Cu2+, Pb2+, Zn2+ and Mn2+ from a solution containing a mixture of all these metal ions, by natural zeolite. In this work is shown compares the adsorption of each heavy metal ion from both single- and multi-component solutions. The amount adsorbed from multi-component solutions was affected significantly, except for Pb2+ where the difference between single and multi-compon...

  7. Conformations of Cationized Peptides. Determination of Ligand Binding Geometries by Irmpd Spectroscopy

    Science.gov (United States)

    Dunbar, Robert C.; Steill, Jeffrey; Oomens, Jos; Polfer, Nick C.

    2009-06-01

    Spectroscopic study of the conformations of metalated amino acids has mapped out in some detail the preferences for canonical (charge solvated) versus zwitterionic (salt bridge) conformations. Corresponding studies of larger peptides are now possible. Here are described results for several singly and doubly charged metal ions with dipeptides and tripeptides. Factors including ion charge, size of cation, and side chain identity and sequence are found to be conformational determinants. IRMPD spectra of the ions were acquired by irradiating the cell with infrared light from the FELIX free electron laser at wavelengths in the approximate range 500 to 1900 cm^{-1}.

  8. A REVIEW ON ACID BASE STATUS IN DAIRY COWS: IMPLICATIONS OF DIETARY CATION-ANION BALANCE

    OpenAIRE

    D. Afzaal, M. Nisa, M. A. Khan and M. Sarwar

    2004-01-01

    The acid base status of a dairy cow is maintained within a narrow range. The key mechanisms involving blood, cells and lungs, perform this function. Although other minerals have an impact on acid base metabolism, the minerals used in dietary cation-anion balance (DCAB) namely sodium (Na), potassium (K) and chloride (Cl) have the greatest effect. Hence, acid base status implicates other biological functions of dairy cows. Low DCAB prepartum reduces the incidence of milk fever and increases the...

  9. 1,3,4-Thiadiazole Derivatives. Part 91. Synthesis and Biological Activity of Metal Complexes of 5-(2-Aminoethyl)-2-Amino-1,3,4-Thiadiazole

    Science.gov (United States)

    Barboiu, Mihai; Cimpoesu, Marilena; Guran, Cornelia

    1996-01-01

    Metal complexes of the title ligand (L) containing Co(II), Ni(II) and Cu(II) were prepared and characterized by elemental analysis, IR, electronic spectroscopy and conductimetry. The new derivatives, possessing the following formulae, CuL2(OH)2, NiL2Cl2, and [Co2LCl4]n showed in vitro antifungal activity against Aspergillus and Candida spp. PMID:18472898

  10. Synthesis, spectroscopic characterization, electrochemistry and biological evaluation of some metal (II) complexes with ONO donor ligand containing benzo[b]thiophene and coumarin moieties

    Science.gov (United States)

    Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

    2014-09-01

    Schiff base ligand 3-chloro-N‧-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzo[b]thiophene-2-carbohydrazide and its Cu(II), Co(II), Ni(II) and Zn(II) complexes were synthesized, characterized by elemental analysis and various physico-chemical techniques like, IR, 1H NMR, ESI-mass, UV-Visible, thermogravimetry - differential thermal analysis, magnetic measurements and molar conductance. Spectral analysis indicates octahedral geometry for all the complexes. Cu(II) complex have 1:1 stoichiometry of the type [M(L)(Cl)(H2O)2], whereas Co(II), Ni(II) and Zn(II) complexes have 1:2 stoichiometric ratio of the type [M(L)2]. The bonding sites are the oxygen atom of amide carbonyl, nitrogen of azomethine function and phenolic oxygen of the Schiff base ligand via deprotonation. The thermogravimetry - differential thermal analysis studies gave evidence for the presence of coordinated water molecules in the composition of Cu(II) complex which was further supported by IR measurements. All the complexes were investigated for their electrochemical activity, but only the Cu(II) complex showed the redox property. In order to evaluate the effect of antimicrobial potency of metal ions upon chelation, ligand and its metal complexes along with their respective metal chlorides were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The results showed that the metal complexes were found to be more active than free ligand. Ligand and its complexes were screened for free radical scavenging activity by DPPH method and DNA cleavage activity using Calf-thymus DNA (Cat. No-105850).

  11. Synthesis, characterization and biological relevance of some metal (II) complexes with oxygen, nitrogen and oxygen (ONO) donor Schiff base ligand derived from thiazole and 2-hydroxy-1-naphthaldehyde

    Science.gov (United States)

    Nagesh, G. Y.; Mruthyunjayaswamy, B. H. M.

    2015-04-01

    The novel Schiff base ligand 2-((2-hydroxynaphthalen-1-yl)methylene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 2-hydroxy-1-naphthaldehyde and its newly synthesized Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes have been characterized by microanalysis, molar conductance, IR, 1H NMR, ESI-mass, UV-Visible, TGA/DTA, ESR and powder X-ray diffraction data to explicate their structures. The IR results confirmed the tridentate binding of the ligand involving oxygen atom of amide carbonyl, azomethine nitrogen and naphthol oxygen. 1H NMR spectral data of the ligand (L) and its Zn(II) complex agreed well with the proposed structures. Thermogravimetric studies for Cu(II) and Ni(II) complexes indicated the presence of coordinated water molecules and the final product is the metal oxide. In order to appraise the effect of antimicrobial activity of metal ions upon chelation, the newly synthesized ligand and its metal complexes were screened for their antimicrobial activity by minimum inhibitory concentration (MIC) method. The DNA cleavage activities were studied using plasmid DNA pBR322 (Bangal re Genei, Bengaluru, Cat. No 105850) as a target molecule by agarose gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties against Artemia salina. Furthermore, the antioxidant activity were determined in vitro by reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH). The ligand exhibited better in vitro-antioxidant activity than its metal complexes.

  12. 1,3,4-thiadiazole derivatives. Part 9. Synthesis and biological activity of metal complexes of 5-(2-aminoethyl)-2-amino-1,3,4-thiadiazole.

    Science.gov (United States)

    Barboiu, M; Cimpoesu, M; Guran, C; Supuran, C T

    1996-01-01

    Metal complexes of the title ligand (L) containing Co(II), Ni(II) and Cu(II) were prepared and characterized by elemental analysis, IR, electronic spectroscopy and conductimetry. The new derivatives, possessing the following formulae, CuL(2)(OH)(2), NiL(2)Cl(2), and [Co(2)LCl(4)](n) showed in vitro antifungal activity against Aspergillus and Candida spp.

  13. Synthesis, spectroscopic studies, thermal analyses, biological activity of tridentate coordinated transition metal complexes of bi(pyridyl-2-ylmethyl)amine]ligand

    Science.gov (United States)

    Abd El-Halim, Hanan F.; Mohamed, Gehad G.

    2016-01-01

    A new tridentate acyclic pincer ligand, [bi(pyridin-2-methyl)amine] (bpma, HL), was synthesized and reacted to form complexes with copper(II), nickel(II), iron(II), cobalt(II) and zinc(II) ions. Both the ligand and its complexes were characterized using elemental analysis, molar conductance, infrared, 1H-NMR-spectroscopy, mass and thermal analyses. According to the spectroscopic data, all of the complexes share the same coordination environment around the metal atoms, consisting two nitrogen-pyridine entities, one nitrogen-methylamine entity, one/two water molecules and/or one/two chloride or bromide ions. Complexes also showed molar conductivity according to the presence of two halide anions outer the coordination sphere except Co(II) and Zn(II) complexes are non electrolytes. Analysis indicates that the metal ions have trigonal bipyramidal structure. Cu(II), Ni(II), Fe(II), Co(II), and Zn(II) metal complexes were screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus (G+) and Escherichia coli, and Pseudomonas aeruginosa (G-) bacteria. They showed remarkable antimicrobial activity.

  14. THE SEPARATION OF BASE METALS FROM PLATINUM METALS BY ION EXCHANGE

    Institute of Scientific and Technical Information of China (English)

    JIANGLingen; HUANGYan

    1992-01-01

    In this paper the separation of base metals Fe,Co,Ni and Cu from the platinum metals on a cation exchanger column was studies.The convenient separation conditions are 0.5mol·dm-3 NaCl,pH=2. The recovery efficiency of Rh is 98%.

  15. Removal of some divalent cations from water by membrane-filtration assisted with alginate.

    Science.gov (United States)

    Fatin-Rouge, Nicolas; Dupont, Alexandra; Vidonne, Alain; Dejeu, Jérome; Fievet, Patrick; Foissy, Alain

    2006-03-01

    The removal of divalent metal ions from hard waters or galvanic wastewater by polymer-assisted membrane filtration using alginate was investigated. The ability of this natural polymer to form aggregates and gels in presence of metal ions was studied, in order to carry out metal removal by ultra or micro-filtration. Alginate titrations have shown the presence of amine groups in addition to carboxylates onto the polymer backbone. The binding properties of alginate with divalent cations have been studied, showing an increasing affinity for Ca2+ over Mg2+ as polymer concentration increases, and the relative affinity Pb2+ > or = Cu2+ > Zn2+ > Ni2+. The softening of hard natural waters was achieved successfully and easily, but needs an optimal alginate concentration approximately 4 x 10(-2) M. The alginate powder can be directly added to hard waters. Except for Ni2+, metal-removal was efficient. Polymer regeneration has shown that Cu2+-complexes are labiles.

  16. Preparation and Characterization of Cationic PLA-PEG Nanoparticles for Delivery of Plasmid DNA

    Science.gov (United States)

    Zou, Weiwei; Liu, Chunxi; Chen, Zhijin; Zhang, Na

    2009-09-01

    The purpose of the present work was to formulate and evaluate cationic poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) nanoparticles as novel non-viral gene delivery nano-device. Cationic PLA-PEG nanoparticles were prepared by nanoprecipitation method. The gene loaded nanoparticles were obtained by incubating the report gene pEGFP with cationic PLA-PEG nanoparticles. The physicochemical properties (e.g., morphology, particle size, surface charge, DNA binding efficiency) and biological properties (e.g., integrity of the released DNA, protection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in Hela cells) of the gene loaded PLA-PEG nanoparticles were evaluated, respectively. The obtained cationic PLA-PEG nanoparticles and gene loaded nanoparticles were both spherical in shape with average particle size of 89.7 and 128.9 nm, polydispersity index of 0.185 and 0.161, zeta potentials of +28.9 and +16.8 mV, respectively. The obtained cationic PLA-PEG nanoparticles with high binding efficiency (>95%) could protect the loaded DNA from the degradation by nuclease and plasma. The nanoparticles displayed sustained-release properties in vitro and the released DNA maintained its structural and functional integrity. It also showed lower cytotoxicity than Lipofectamine 2000 and could successfully transfect gene into Hela cells even in presence of serum. It could be concluded that the established gene loaded cationic PLA-PEG nanoparticles with excellent properties were promising non-viral nano-device, which had potential to make cancer gene therapy achievable.

  17. Preparation and Characterization of Cationic PLA-PEG Nanoparticles for Delivery of Plasmid DNA

    Directory of Open Access Journals (Sweden)

    Zou Weiwei

    2009-01-01

    Full Text Available Abstract The purpose of the present work was to formulate and evaluate cationic poly(lactic acid-poly(ethylene glycol (PLA-PEG nanoparticles as novel non-viral gene delivery nano-device. Cationic PLA-PEG nanoparticles were prepared by nanoprecipitation method. The gene loaded nanoparticles were obtained by incubating the report gene pEGFP with cationic PLA-PEG nanoparticles. The physicochemical properties (e.g., morphology, particle size, surface charge, DNA binding efficiency and biological properties (e.g., integrity of the released DNA, protection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in Hela cells of the gene loaded PLA-PEG nanoparticles were evaluated, respectively. The obtained cationic PLA-PEG nanoparticles and gene loaded nanoparticles were both spherical in shape with average particle size of 89.7 and 128.9 nm, polydispersity index of 0.185 and 0.161, zeta potentials of +28.9 and +16.8 mV, respectively. The obtained cationic PLA-PEG nanoparticles with high binding efficiency (>95% could protect the loaded DNA from the degradation by nuclease and plasma. The nanoparticles displayed sustained-release properties in vitro and the released DNA maintained its structural and functional integrity. It also showed lower cytotoxicity than Lipofectamine 2000 and could successfully transfect gene into Hela cells even in presence of serum. It could be concluded that the established gene loaded cationic PLA-PEG nanoparticles with excellent properties were promising non-viral nano-device, which had potential to make cancer gene therapy achievable.

  18. Improved cellular activity of antisense peptide nucleic acids by conjugation to a cationic peptide-lipid (CatLip) domain

    DEFF Research Database (Denmark)

    Koppelhus, Uffe; Shiraishi, Takehiko; Zachar, Vladimir;

    2008-01-01

    for future in vivo applications. We find that simply conjugating a lipid domain (fatty acid) to the cationic peptide (a CatLip conjugate) increases the biological effect of the corresponding PNA (CatLip) conjugates in a luciferase cellular antisense assay up to 2 orders of magnitude. The effect increases...

  19. Structurally Distinct Cation Channelrhodopsins from Cryptophyte Algae.

    Science.gov (United States)

    Govorunova, Elena G; Sineshchekov, Oleg A; Spudich, John L

    2016-06-01

    Microbial rhodopsins are remarkable for the diversity of their functional mechanisms based on the same protein scaffold. A class of rhodopsins from cryptophyte algae show close sequence homology with haloarchaeal rhodopsin proton pumps rather than with previously known channelrhodopsins from chlorophyte (green) algae. In particular, both aspartate residues that occupy the positions of the chromophore Schiff base proton acceptor and donor, a hallmark of rhodopsin proton pumps, are conserved in these cryptophyte proteins. We expressed the corresponding polynucleotides in human embryonic kidney (HEK293) cells and studied electrogenic properties of the encoded proteins with whole-cell patch-clamp recording. Despite their lack of residues characteristic of the chlorophyte cation channels, these proteins are cation-conducting channelrhodopsins that carry out light-gated passive transport of Na(+) and H(+). These findings show that channel function in rhodopsins has evolved via multiple routes. PMID:27233115

  20. The addition of organic carbon and nitrate affects reactive transport of heavy metals in sandy aquifers

    KAUST Repository

    Satyawali, Yamini

    2011-04-01

    Organic carbon introduction in the soil to initiate remedial measures, nitrate infiltration due to agricultural practices or sulphate intrusion owing to industrial usage can influence the redox conditions and pH, thus affecting the mobility of heavy metals in soil and groundwater. This study reports the fate of Zn and Cd in sandy aquifers under a variety of plausible in-situ redox conditions that were induced by introduction of carbon and various electron acceptors in column experiments. Up to 100% Zn and Cd removal (from the liquid phase) was observed in all the four columns, however the mechanisms were different. Metal removal in column K1 (containing sulphate), was attributed to biological sulphate reduction and subsequent metal precipitation (as sulphides). In the presence of both nitrate and sulphate (K2), the former dominated the process, precipitating the heavy metals as hydroxides and/or carbonates. In the presence of sulphate, nitrate and supplemental iron (Fe(OH)3) (K3), metal removal was also due to precipitation as hydroxides and/or carbonates. In abiotic column, K4, (with supplemental iron (Fe(OH)3), but no nitrate), cation exchange with soil led to metal removal. The results obtained were modeled using the reactive transport model PHREEQC-2 to elucidate governing processes and to evaluate scenarios of organic carbon, sulphate and nitrate inputs. © 2010 Elsevier B.V.