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Sample records for platinumii carbonate complex

  1. The Chameleonic Nature of Platinum(II) Imidazopyridine Complexes.

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    Pinter, Piermaria; Pittkowski, Rebecca; Soellner, Johannes; Strassner, Thomas

    2017-10-12

    The synthesis and characterization of cyclometalated C^C* platinum(II) complexes with unique photophysical properties, aggregation induced enhancement of the quantum yields with a simultaneous decrease of phosphorescence lifetimes, is reported. Additionally, a change of emission color is induced by variation of the excitation wavelength. The aggregation behavior of these complexes is controlled by the steric demand of the substituents. The photophysical properties of these complexes are investigated through emission-excitation matrix analysis (EEM). The monomeric complexes are excellent room temperature phosphorescent blue emitters with emission maxima below 470 nm and quantum yields of up to 93 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Platinum(II) complexes as spectroscopic probes for biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Ratilla, E.

    1990-09-21

    The use of platinum(II) complexes as tags and probes for biomolecules is indeed advantageous for their reactivities can be selective for certain purposes through an interplay of mild reaction conditions and of the ligands bound to the platinum. The use of {sup 195}Pt NMR as a method of detecting platinum and its interactions with biomolecules was carried out with the simplest model of platinum(II) tagging to proteins. Variable-temperature {sup 195}Pt NMR spectroscopy proved useful in studying the stereodynamics of complex thioethers like methionine. The complex, Pt(trpy)Cl{sup +}, with its chromophore has a greater potential for probing proteins. It is a noninvasive and selective tag for histidine and cysteine residues on the surface of cytochrome c at pH 5. The protein derivatives obtained are separable, and the tags are easily quantitated and differentiated through the metal-to-ligand charge transfer bands which are sensitive to the environment of the tag. Increasing the pH to 7.0 led to the modification by Pt(trpy)Cl{sup +}of Arg 91 in cytochrome c. Further studies with guanidine-containing ligands as models for arginine modification by Pt(trpy)Cl{sup +} showed that guanidine can act as a terminal ligand and as a bridging ligand. Owing to the potential utility of Pt(trpy)L{sup n+} as electron dense probes of nucleic acid structure, interactions of this bis-Pt(trpy){sup 2+} complex with nucleic acids was evaluated. Indeed, the complex interacts non-covalently with nucleic acids. Its interactions with DNA are not exactly the same as those of its precedents. Most striking is its ability to form highly immobile bands of DNA upon gel electrophoresis. 232 refs.

  3. C60 Recognition from Extended Tetrathiafulvalene Bis-acetylide Platinum(II) Complexes.

    Science.gov (United States)

    Bastien, Guillaume; Dron, Paul I; Vincent, Manon; Canevet, David; Allain, Magali; Goeb, Sébastien; Sallé, Marc

    2016-11-18

    The favorable spatial organization imposed by the square planar 4,4'-di(tert-butyl)-2,2'-bipyridine (dbbpy) platinum(II) complex associated with the electronic and shape complementarity of π-extended tetrathiafulvalene derivatives (exTTF) toward fullerenes is usefully exploited to construct molecular tweezers, which display good affinities for C 60 .

  4. Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

    Science.gov (United States)

    Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

    2014-10-03

    The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Interaction of Newly Platinum(II) with Tris(2-carboxyethyl)phosphine Complex with DNA and Model Lipid Membrane

    Czech Academy of Sciences Publication Activity Database

    Pruchnik, H.; Kral, Teresa; Hof, Martin

    2017-01-01

    Roč. 250, č. 5 (2017), s. 461-470 ISSN 0022-2631 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388955 Keywords : dna * DPPC bilayer * dsc * IR spectroscopy * Platinum(II) complex * tcspc-fcs Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.696, year: 2016

  6. Synthesis and characterization of platinum(II) complexes with 2,2'-bipyridine derivative supporting ligands.

    Science.gov (United States)

    Yang, Kwang Woon; Hwang, Hey Eun; Jung, Hee Sun; Kwak, Chee Hun; Lee, Ji Hoon; Jung, Sang-Chul; Ahn, Ho Geun; Chung, Min Chul

    2011-08-01

    The reaction of the [Pt(bpy-R)Cl2](bpy-R: R=H (2,2'-bipyridine); R=CH3 (4,4'-dimethyl-2,2'-biypridine (DM-bpy), 3,3'-5,5'-tertamethyl-2,2'-bipyridiyl (TM-bpy)) with 1,4-Bis(5'-2',2"-bipyridine)benzene (bpy-Ph-bpy) affords the following mono- and di-platinum complexes of [(bpy)Pt(bpy-Ph-bpy)][PF6]2 (1), [(bpy)Pt(bpy-Ph-bpy)Pt(bpy)])[PF6]4 (2), [(DM-bpy)Pt(bpy-Ph-bpy)])][PF6]2 (3), and [(TM-bpy)Pt(bpy-ph-bpy)[PF6]2 (4), respectively. These complexes were characterized by NMR, IR, UV/VIS, PL and cyclic voltammetry. The internal quantum yields of these platinum(II) complexes are very high (0.83-0.99) and these complexes emit light at deep blue regions (373-417 nm). The redox behavior of complexes 1 and 2 shows quasi-reversible process.

  7. N6-Benzyladenosine Derivatives as Novel N-Donor Ligands of Platinum(II Dichlorido Complexes

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    Ján Vančo

    2013-06-01

    Full Text Available The platinum(II complexes trans-[PtCl2(Ln2]∙xSolv 1–13 (Solv = H2O or CH3OH, involving N6-benzyladenosine-based N-donor ligands, were synthesized; Ln stands for N6-(2-methoxybenzyladenosine (L1, involved in complex 1, N6-(4-methoxy-benzyladenosine (L2, 2, N6-(2-chlorobenzyladenosine (L3, 3, N6-(4-chlorobenzyl-adenosine (L4, 4, N6-(2-hydroxybenzyladenosine (L5, 5, N6-(3-hydroxybenzyl-adenosine (L6, 6, N6-(2-hydroxy-3-methoxybenzyladenosine (L7, 7, N6-(4-fluoro-benzyladenosine (L8, 8, N6-(4-methylbenzyladenosine (L9, 9, 2-chloro-N6-(3-hydroxy-benzyladenosine (L10, 10, 2-chloro-N6-(4-hydroxybenzyladenosine (L11, 11, 2-chloro-N6-(2-hydroxy-3-methoxybenzyladenosine (L12, 12 and 2-chloro-N6-(2-hydroxy-5-methylbenzyladenosine (L13, 13. The compounds were characterized by elemental analysis, mass spectrometry, IR and multinuclear (1H-, 13C-, 195Pt- and 15N- and two-dimensional NMR spectroscopy, which proved the N7-coordination mode of the appropriate N6-benzyladenosine derivative and trans-geometry of the title complexes. The complexes 1–13 were found to be non-toxic in vitro against two selected human cancer cell lines (HOS and MCF7; with IC50 > 50.0 µM. However, they were found (by ESI-MS study to be able to interact with the physiological levels of the sulfur-containing biogenic biomolecule L-methionine by a relatively simple 1:1 exchange mechanism (one Ln molecule was replaced by one L-methionine molecule, thus forming a mixed-nitrogen/sulfur-ligand dichlorido-platinum(II coordination species.

  8. Synthesis and coordination behavior of a bipyridine platinum(II) complex with thioglucose.

    Science.gov (United States)

    Tsuji, Takaaki; Kuwamura, Naoto; Yoshinari, Nobuto; Konno, Takumi

    2013-05-06

    A mononuclear platinum(II) complex with two monodentate-S H4tg(-) ligands, [Pt(H4tg-κS)2(bpy)] (1), was newly synthesized by the reaction of [PtCl2(bpy)] (bpy = 2,2'-bipyridyl) with NaH4tg (NaH4tg =1-thio-β-d-glucose sodium salt) in water. Complex 1 reacted with additional [PtCl2(bpy)] in water to give an S-bridged dinuclear complex, [Pt2(μ2-H4tg-κ(1)S:κ(1)S)2(bpy)2](2+) ([2](2+)), in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [Pt(bpy)](2+) moiety through two thiolato groups. Treatments of 1 with Cu(2+) and Ni(2+) in water in the presence of bpy produced S-bridged dinuclear complexes [PtCu(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([3](2+)) and [PtNi(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([4](2+)), respectively, in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [M(bpy)](2+) (M = Cu(II), Ni(II)) moiety through two thiolato and two hydroxyl groups to form a chiral [M(N)2(O)2(S)2] octahedron with the Δ configuration. On the other hand, similar treatment with Cd(2+) in the presence of bpy resulted in the formation of an S-bridged trinuclear complex, [Cd{Pt(μ2-H4tg-κ(1)S:κ(2)O,S)(μ2-H4tg-κ(1)S:κ(1)S)(bpy)}2](2+) ([5](2+)), in which each of two square-planar [Pt(H4tg)2(bpy)] units binds to a Cd(II) ion through two thiolato groups and one hydroxyl group to form a chiral [Cd(O)2(S)4] octahedron with the Λ configuration. Of two geometrical configurations, syn and anti, which arise from the relative arrangement of two β-D-pyranose moieties, [2](2+) adopts the syn configuration with symmetric bridging sulfur atoms, while [3](2+), [4](2+), and [5](2+) all have the anti configuration with R configurational bridging sulfur atoms. All of the complexes were fully characterized by electronic absorption, CD, and NMR spectroscopies, along with single-crystal X-ray crystallography.

  9. Synthesis, structural characterization, and pro-apoptotic activity of 1-indanone thiosemicarbazone platinum(II) and palladium(II) complexes: potential as antileukemic agents.

    Science.gov (United States)

    Gómez, Natalia; Santos, Diego; Vázquez, Ramiro; Suescun, Leopoldo; Mombrú, Alvaro; Vermeulen, Monica; Finkielsztein, Liliana; Shayo, Carina; Moglioni, Albertina; Gambino, Dinorah; Davio, Carlos

    2011-08-01

    In the search for alternative chemotherapeutic strategies against leukemia, various 1-indanone thiosemicarbazones, as well as eight novel platinum(II) and palladium(II) complexes, with the formula [MCl₂(HL)] and [M(HL)(L)]Cl, derived from two 1-indanone thiosemicarbazones were synthesized and tested for antiproliferative activity against the human leukemia U937 cell line. The crystal structure of [Pt(HL1)(L1)]Cl·2MeOH, where L1=1-indanone thiosemicarbazone, was solved by X-ray diffraction. Free thiosemicarbazone ligands showed no antiproliferative effect, but the corresponding platinum(II) and palladium(II) complexes inhibited cell proliferation and induced apoptosis. Platinum(II) complexes also displayed selective apoptotic activity in U937 cells but not in peripheral blood monocytes or the human hepatocellular carcinoma HepG2 cell line used to screen for potential hepatotoxicity. Present findings show that, in U937 cells, 1-indanone thiosemicarbazones coordinated to palladium(II) were more cytotoxic than those complexed with platinum(II), although the latter were found to be more selective for leukemic cells suggesting that they are promising compounds with potential therapeutic application against hematological malignancies. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. How do ligands influence the quantum yields of cyclometalated platinum(ii) complexes, a theoretical research study.

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    Yang, Baozhu; Huang, Shuang; Wang, Jianhao

    2017-08-30

    A series of cyclometalated platinum(ii) complexes have been investigated with the TDDFT method. These complexes have similar structures but distinct phosphorescence quantum yields. Theoretical calculations were carried out to explain the differences in quantum yields from the conjugation effect of the cyclometalated ligand, molecular rigidity and ligand-field strength of the monodentate ligand. The radiative decay rate constants (k r ) have been discussed with the oscillator strength (f n ), the strength of the spin-orbit coupling (SOC) interaction between the lowest energy triplet excited state (T 1 ) and singlet excited states (S n ), and the energy gaps between E(T 1 ) and E(S n ). To illustrate the nonradiative decay processes, the transition states (TS) between the triplet metal-centered state ( 3 MC) and T 1 states have been optimized. In addition, the minimum energy crossing points (MECPs) between 3 MC and the ground states (S 0 ) were optimized. Finally, the potential energy curves along the nonradiative decay pathways are simulated. To obtain a phosphorescent complex with a high quantum yield, the complex should retain molecular rigidity well in the S 1 and T 1 states, while showing significant structural distortion at the MECP structure.

  11. A bioaccumulative cyclometalated platinum(II) complex with two-photon-induced emission for live cell imaging.

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    Koo, Chi-Kin; Wong, Ka-Leung; Man, Cornelia Wing-Yin; Lam, Yun-Wah; So, Leo King-Yan; Tam, Hoi-Lam; Tsao, Sai-Wah; Cheah, Kok-Wai; Lau, Kai-Chung; Yang, Yang-Yi; Chen, Jin-Can; Lam, Michael Hon-Wah

    2009-02-02

    The cyclometalated platinum(II) complex [Pt(L)Cl], where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine containing C(phenyl), N(pyridyl), and N(pyrazolyl) donor moieties, was found to possess two-photon-induced luminescent properties. The two-photon-absorption cross section of the complex in N,N-dimethylformamide at room temperature was measured to be 20.8 GM. Upon two-photon excitation at 730 nm from a Ti:sapphire laser, bright-green emission was observed. Besides its two-photon-induced luminescent properties, [Pt(L)Cl] was able to be rapidly accumulated in live HeLa and NIH3T3 cells. The two-photon-induced luminescence of the complex was retained after live cell internalization and can be observed by two-photon confocal microscopy. Its bioaccumulation properties enabled time-lapse imaging of the internalization process of the dye into living cells. Cytotoxicity of [Pt(L)Cl] to both tested cell lines was low, according to MTT assays, even at loadings as high as 20 times the dose concentration for imaging for 6 h.

  12. Synthesis, Characterization and in Vitro Antitumor Activity of Platinum(II Oxalato Complexes Involving 7-Azaindole Derivatives as Coligands

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    Pavel Štarha

    2014-07-01

    Full Text Available The platinum(II oxalato complexes [Pt(ox(naza2] (1–3 were synthesized and characterized by elemental analysis (C, H, N, multinuclear NMR spectroscopy (1H, 13C, 15N, 195Pt and electrospray ionization mass spectrometry (ESI-MS; naza = 4-chloro-7-azaindole (4Claza; 1, 3-bromo-7-azaindole (3Braza; 2 or 4-bromo-7-azaindole (4Braza; 3. The prepared substances were screened for their in vitro antitumor activity on the osteosarcoma (HOS and breast adenocarcinoma (MCF7 human cancer cell lines, where 2 showed moderate antitumor effect (IC50 = 27.5 μM, and 18.3 μM, respectively. The complex 2 was further tested on a panel of six others human cancer cell lines, including the malignant melanoma (G361, cervix carcinoma (HeLa, ovarian carcinoma (A2780, cisplatin-resistant ovarian carcinoma (A2780R, lung carcinoma (A549 and prostate adenocarcinoma (LNCaP. This substance was found to be moderate antitumor effective against G361 (IC50 = 17.3 μM, HeLa (IC50 = 31.8 μM and A2780 (IC50 = 19.2 μM cell lines. The complex 2 was also studied by NMR for its solution stability and by ESI-MS experiments for its ability to interact with biomolecules, such as cysteine, glutathione or guanosine 5'-monophosphate.

  13. Oxidative Reactivity and Cytotoxic Properties of a Platinum(II) Complex Prepared by Outer-Sphere Amide Bond Coupling

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    Wilson, Justin J.; Lippard, Stephen J.

    2012-01-01

    Benzyl amine was coupled to the dangling carboxylic acid groups of the platinum(II) complex [Pt(edda)Cl2], where edda = ethylenediamine-N,N’-diacetic acid, to give the diamidetethered complex [Pt(L)Cl2] (1), where L = ethylenediamine-N,N’-bis(N-benzylacetamide). Complex 1 was oxidized with both PhICl2 and Br2. Oxidation with PhICl2 cleanly afforded the tetrachloride complex, [Pt(L)Cl4] (2), whereas oxidation with Br2 gave rise to several mixed halide complexes of the general formula, [Pt(L)ClxBr4-x], where x = 1, 2, or 3. Complexes 1 and 2 were fully characterized by 1H, 13C, and 195Pt NMR spectroscopy, as well as by ESI-MS. These compounds exist as a mixture of diastereomers that arise from the chirality of the two coordinated nitrogen atoms. Crystal structures of 1, 2, and [Pt(L)ClxBry] (3) are reported. Although refined as the tetrabromide complex [Pt(L)Br4], the crystal structure of 3 is a mixture of species with site-occupancy disorder of chloride and bromide ligands. DFT calculations indicate that the two sets of diastereomers of 1 and 2 are effectively thermoneutral, a conclusion that is also supported by the observation of both members of each pair by NMR spectroscopy. The cytotoxicity of 1 and 2 was measured by the MTT assay in HeLa cells and compared to that of cisplatin. Both exhibit IC50 values close to 50 μM and are therefore substantially less toxic than cisplatin, for which the IC50 is 1 μM. PMID:24489429

  14. Relative cytotoxicity of complexes of platinum(II and palladium(II against pure cell culture Paramecium caudatum and human cell lines A431 and HaCaT

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    Aleksei Vladimirovich Eremin

    2018-04-01

    Full Text Available The results of cytotoxicity cisplatin-like complexes of platinum(II and palladium(II are presented. The cytotoxicity was researched by method of  biotesting with Paramecium caudatum and by MTT-assay with human cells: epidermoid carcimoma A431 and minimal transformed aneuploid keratinocytes HaCaT. Cytotoxicity of complexes toward protists is high, however, comparatively HaCaT are more sensitive than A431. Furthemore, cytotoxicity of palladium(II complexes is higher than the analogues with platinum(II.

  15. Synthesis and photoinduced electron transfer in platinum(II) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes.

    Science.gov (United States)

    Lee, Sai-Ho; Chan, Chris Tsz-Leung; Wong, Keith Man-Chung; Lam, Wai Han; Kwok, Wai-Ming; Yam, Vivian Wing-Wah

    2014-12-21

    Platinum(ii) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes, (Cbz)2-Pt(bpy)-C60 and ((t)BuCbz)2-Pt(bpy)-C60, were synthesized. Their photophysical properties were studied by electronic absorption and emission spectroscopy and the origin of the transitions was supported by computational studies. The electrochemical properties were also studied and the free energies for charge-separation and charge-recombination processes were evaluated. The photoinduced electron transfer reactions in the triads were investigated by femtosecond and nanosecond transient absorption spectroscopy. In dichloromethane, both triads undergo ultrafast charge separation from the (3)MLCT/LLCT excited state within 300 fs to yield their respective triplet charge-separated (CS) states, namely (Cbz)2˙(+)-Pt(bpy)-C60˙(-) and ((t)BuCbz)2˙(+)-Pt(bpy)-C60˙(-), and the CS states would undergo charge recombination to give the (3)C60* state, which subsequently decays to the ground state in 22-28 μs.

  16. Highly Luminescent Dinuclear Platinum(II) Complexes Incorporating Bis-Cyclometallating Pyrazine-Based Ligands: A Versatile Approach to Efficient Red Phosphors

    OpenAIRE

    Culham, Stacey; Lanoe, Pierre-Henri; Whittle, Victoria; Durrant, Marcus; Williams, Gareth; Kozhevnikov, Valery

    2013-01-01

    A series of luminescent dinuclear platinum(II) complexes incorporating diphenylpyrazine-based bridging ligands ((LH2)-H-n) has been prepared. Both 2,5-diphenylpyrazine ((LH2)-H-2) and 2,3-diphenylpyrazine ((LH2)-H-3) are able to undergo cyclometalation of the two phenyl rings, with each metal ion binding to the two nitrogen atoms of the central heterocycle, giving, after treatment with the anion of dipivaloyl methane (dpm), complexes of formula \\{Pt(dpm)\\}(2)L-n. These compounds are isomers o...

  17. Dimensional Control and Morphological Transformations of Supramolecular Polymeric Nanofibers Based on Cofacially-Stacked Planar Amphiphilic Platinum(II) Complexes.

    Science.gov (United States)

    Robinson, Matthew E; Nazemi, Ali; Lunn, David J; Hayward, Dominic W; Boott, Charlotte E; Hsiao, Ming-Siao; Harniman, Robert L; Davis, Sean A; Whittell, George R; Richardson, Robert M; De Cola, Luisa; Manners, Ian

    2017-09-26

    Square-planar platinum(II) complexes often stack cofacially to yield supramolecular fiber-like structures with interesting photophysical properties. However, control over fiber dimensions and the resulting colloidal stability is limited. We report the self-assembly of amphiphilic Pt(II) complexes with solubilizing ancillary ligands based on polyethylene glycol [PEG n , where n = 16, 12, 7]. The complex with the longest solubilizing PEG ligand, Pt-PEG 16 , self-assembled to form polydisperse one-dimensional (1D) nanofibers (diameters fibers of length up to ca. 400 nm. The fiber lengths were dependent on the Pt-PEG 16 complex to seed mass ratio in a manner analogous to a living covalent polymerization of molecular monomers. Moreover, the fiber lengths were unchanged in solution after 1 week and were therefore "static" with respect to interfiber exchange processes on this time scale. In contrast, similarly formed near-uniform fibers of Pt-PEG 12 exhibited dynamic behavior that led to broadening of the length distribution within 48 h. After aging for 4 weeks in solution, Pt-PEG 12 fibers partially evolved into 2D platelets. Furthermore, self-assembly of Pt-PEG 7 yielded only transient fibers which rapidly evolved into 2D platelets. On addition of further fiber-forming Pt complex (Pt-PEG 16 ), the platelets formed assemblies via the growth of fibers selectively from their short edges. Our studies demonstrate that when interfiber dynamic exchange is suppressed, dimensional control and hierarchical structure formation are possible for supramolecular polymers through the use of kinetically controlled seeded growth methods.

  18. A Potential Bone-Targeting Hypotoxic Platinum(II) Complex with an Unusual Cytostatic Mechanism toward Osteosarcoma Cells.

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    Zhang, Zhenqin; Zhu, Zhenzhu; Luo, Cheng; Zhu, Chengcheng; Zhang, Changli; Guo, Zijian; Wang, Xiaoyong

    2018-03-19

    Osteosarcoma (OS) is the most common primary pediatric bone tumor lethal to children and adolescents. Chemotherapeutic agents such as cisplatin are not effective for OS because of their poor accessibility to this cancer and severe systemic toxicity. In this study, a lipophilic platinum(II) complex bearing a bisphosphonate bone-targeting moiety, cis-[PtL(NH 3 ) 2 Cl]NO 3 {BPP; L = tetraethyl [2-(pyridin-2-yl)ethane-1,1-diyl]bisphosphonate}, was prepared and characterized by NMR, electrospray ionization mass spectrometry, and single-crystal X-ray crystallography. The cytotoxicity of BPP toward OS cell lines U2OS and MG-63 was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. BPP exhibits moderate inhibition against U2OS cells through a mechanism involving both DNA binding and a mevalonate pathway. The acute toxicity of BPP to mice is 7-fold lower than that of cisplatin. The relative low systemic toxicity may result from the steric hindrance of the ligand, which blocks BPP approaching the bases of DNA. The results suggest that incorporating bisphosphonates into a platinum complex not only enhances its bone-targeting property but also minimizes its reactivity toward DNA and thereby lowers the systematic toxicity of the complex. The diminished cytotoxicity of BPP could be compensated for by increasing the therapeutic dose with marginal harm. This strategy provides a new possibility for overcoming the ineffectiveness and systemic toxicity of platinum drugs in the treatment of OS.

  19. Trans- and cis-2-phenylindole platinum(II) complexes as cytotoxic agents against human breast adenocarcinoma cell lines

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    Tomé, Maria; López, Concepción; González, Asensio; Ozay, Bahadir; Quirante, Josefina; Font-Bardía, Mercè; Calvet, Teresa; Calvis, Carme; Messeguer, Ramon; Baldomá, Laura; Badía, Josefa

    2013-09-01

    The synthesis and characterization of the new 2-phenylindole derivative: C8H3N-2-C6H5-3NOMe-5OMe (3c) and the trans- and cis-isomers of [Pt(3c)Cl2(DMSO)] complexes (4c and 5c, respectively) are described. The crystal structures of 4c·CH2Cl2 and 5c confirm: (a) the existence of a Pt-Nindole bond, (b) the relative arrangement of the Cl- ligands [trans- (in 4c) or cis- (in 5c)] and (c) the anti-(E) configuration of the oxime. The cytotoxic assessment of C8H3N-2-(C6H4-4‧R1)-3NOMe-5R2 [with R1 = R2 = H (3a); R1 = Cl, R2 = H (3b) and R1 = H, R2 = OMe (3c)] and the geometrical isomers of [Pt(L)Cl2(DMSO)] with L = 3a-3c [trans- (4a-4c) and cis- (5a-5c), respectively] against human breast adenocarcinoma cell lines (MDA-MB231 and MCF-7) is also reported and reveals that all the platinum(II) complexes (except 4a) are more cytotoxic than cisplatin in front of the MCF7 cell line. Electrophoretic DNA migration studies of the synthesized compounds in the absence and in the presence of topoisomerase-I have been performed, in order to get further insights into their mechanism of action.

  20. Photoactive platinum(II) complexes of nonsteroidal anti-inflammatory drug naproxen: Interaction with biological targets, antioxidant activity and cytotoxicity.

    Science.gov (United States)

    Srivastava, Payal; Singh, Khushbu; Verma, Madhu; Sivakumar, Sri; Patra, Ashis K

    2018-01-20

    The effect on the therapeutic efficacy of Pt(II) complexes on combining non-steroidal anti-inflammatory drugs (NSAIDs) is an attractive strategy to circumvent chronic inflammation mediated by cancer and metastasis. Two square-planar platinum(II) complexes: [Pt(dach)(nap)Cl] (1) and [Pt(dach)(nap) 2 ] (2), where dach = (1R,2R)-dichloro(cyclohexane-1,2-diamine) and NSAID drug naproxen (nap), have been designed for studying their biological activity. The naproxen bound to the Pt(II) centre get released upon photoirradiation with low-power UV-A light as confirmed by the significant enhancement in emission intensities of the complexes. The compounds were evaluated for their photophysical properties, photostability, reactivity with 5'-guanosine monophophosphate (5'-GMP), interactions with CT-DNA and BSA, antioxidant activity and reactive oxygen species mediated photo-induced DNA damage properties. ESI-MS studies demonstrated the formation of bis-adduct with 5'-GMP and the formation of Pt II -DNA crosslinks by gel electrophoretic mobility shift assay and ITC studies. The interaction of the complexes 1 and 2 with the CT-DNA exhibits potential binding affinity (K b  ∼ 10 4  M -1 , K app ∼ 10 5  M -1 ), implying intercalation to CT-DNA through planar naphthyl ring of the complexes. Both the complexes also exhibit strong binding affinity towards BSA (K BSA ∼ 10 5  M -1 ). The complexes exhibit efficient DNA damage activity on irradiation at 365 nm via formation of singlet oxygen ( 1 O 2 ) and hydroxyl radical ( • OH) under physiological conditions. Both the complexes were cytotoxic in dark and exhibit significant enhancement of cytotoxicity upon photo-exposure against HeLa and HepG2 cancer cells giving IC 50 values ranging from 8 to 12 μM for 1 and 2. The cellular internalization data showed cytosolic and nuclear localization of the complexes in the HeLa cells. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  1. Structure of the Hydrated Platinum(II) Ion And the Cis-Diammine-Platinum(II) Complex in Acidic Aqueous Solution: An EXAFS Study

    Energy Technology Data Exchange (ETDEWEB)

    Jalilehvand, F.; Laffin, L.J.

    2009-05-18

    Careful analysis of Pt L{sub 3}-edge extended X-ray absorption fine structure (EXAFS) spectra shows that the hydrated platinum(II) ion in acidic (HClO{sub 4}) aqueous solution binds four water molecules with the Pt-O bond distance 2.01(2) {angstrom} and one (or two) in the axial position at 2.39(2) {angstrom}. The weak axial water coordination is in accordance with the unexpectedly small activation volume previously reported for water exchange in an interchange mechanism with associative character. The hydrated cis-diammineplatinum(II) complex has a similar coordination environment with two ammine and two aqua ligands strongly bound with Pt-O/N bond distances of 2.01(2) {angstrom} and, in addition, one (or two) axial water molecule at 2.37(2) {angstrom}. This result provides a new basis for theoretical computational studies aiming to connect the function of the anticancer drug cis-platin to its ligand exchange reactions, where usually four-coordinated square planar platinum(II) species are considered as the reactant and product. {sup 195}Pt NMR spectroscopy has been used to characterize the Pt(II) complexes.

  2. Synthesis and Characterization of Platinum(II) Complexes with Various Substituted 2,2'-Bipyridine Ligands.

    Science.gov (United States)

    Son, Seokhwan; Lee, Hwan Gyu; Lee, Nopl; Ryu, Minwoo; Kwak, Cheenhun; Lee, Jihoon; Ahn, Hogeun; Chung, Minchu

    2016-02-01

    The reaction of platinum 5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)di-2,2'-bipyridine with 2,2'-bipyridine) PtCI2, (1,10-phenanthroline)PtC2 and (2,2'-bipyrimidine)PtC2: (2,2'-bipyridine)Pt[5,5"-(9,9-dioctyl-9H- fluorene-2,7-diyl)di-2,2'-bipyridine] (1) (2,2'-bipyrimi-dine)Pt[5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)di- 2,2'-bipyridine] (2) (1,10-Phenantroline)-Pt[5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)di-2,2'-bipyridine] (3). In the study, new platinum complex compounds were synthesized utilizing the ligand of a 5,5"-(9,9- dioctyl-9H-fluorene-2,7-diyl)di-2,2'-bipyridine). Each of the three complexes was obtained through the reaction carried out in this study. These complexes were analyzed using 1H(13C)-NMR, PL, and a UV-vis spectrophotometer. The maximum wavelengths of complexes 1, 2, and 3 appear at 519 nm, 375 nm, and 517 nm, respectively. The quantum yields of these complexes are in the range of 0.35-0.67.

  3. Photodynamic killing of cancer cells by a Platinum(II) complex with cyclometallating ligand

    Science.gov (United States)

    Doherty, Rachel E.; Sazanovich, Igor V.; McKenzie, Luke K.; Stasheuski, Alexander S.; Coyle, Rachel; Baggaley, Elizabeth; Bottomley, Sarah; Weinstein, Julia A.; Bryant, Helen E.

    2016-03-01

    Photodynamic therapy that uses photosensitizers which only become toxic upon light-irradiation provides a strong alternative to conventional cancer treatment due to its ability to selectively target tumour material without affecting healthy tissue. Transition metal complexes are highly promising PDT agents due to intense visible light absorption, yet the majority are toxic even without light. This study introduces a small, photostable, charge-neutral platinum-based compound, Pt(II) 2,6-dipyrido-4-methyl-benzenechloride, complex 1, as a photosensitizer, which works under visible light. Activation of the new photosensitizer at low concentrations (0.1-1 μM) by comparatively low dose of 405 nm light (3.6 J cm-2) causes significant cell death of cervical, colorectal and bladder cancer cell lines, and, importantly, a cisplatin resistant cell line EJ-R. The photo-index of the complex is 8. We demonstrate that complex 1 induces irreversible DNA single strand breaks following irradiation, and that oxygen is essential for the photoinduced action. Neither light, nor compound alone led to cell death. The key advantages of the new drug include a remarkably fast accumulation time (diffusion-controlled, minutes), and photostability. This study demonstrates a highly promising new agent for photodynamic therapy, and attracts attention to photostable metal complexes as viable alternatives to conventional chemotherapeutics, such as cisplatin.

  4. Thermal decomposition of vinyl- and allylsilane platinum(II complexes and platinum(II catalysed synthesis of (E,(E-1,4-diphenyl-1,3-butadiene

    Directory of Open Access Journals (Sweden)

    Paul P. Mebe

    2008-12-01

    Full Text Available Thermal stabilities of Pt(II complexes: K[PtCl3(CH2=CHSiMe3], K[PtCl3(CH2=CHCH2SiMe3], K[(acacPtCl(CH2=CHSiMe3] and [PtCl(CH2=CHCH2SiMe3]2, were examined. All complexes were found to be stable at room temperature but they decomposed without melting above about 90 oC. The allylsilane complex decomposed above about 125 oE,(E-1,4-diphenyl-1,3-butadiene was stereoselectively synthesised in good yield from (E-β-styrylsilane in the presence of Zeise’s salt.

  5. Platinum(II Complexes with Tetradentate Schiff Bases as Ligands: Synthesis, Characterization and Detection of DNA Interaction by Differential Pulse Voltammetry

    Directory of Open Access Journals (Sweden)

    Lijun Li

    2012-01-01

    Full Text Available Five sterically hindered platinum(II complexes with tetradentate schiff bases as ligands, [Pt(L] (L= N,N′-bisalicylidene-1,2-ethylenediamine (L1, N,N′-bisalicylidene-1,2-cyclohexanediamine (L2, N,N′-bis(5-hydroxyl-salicylidene-1,2-cyclohexanediamine (L3, N,N′-bisalicylidene-1,2-diphenyl-ethylenediamine (L4 and N,N′-bis(3-tert-butyl-5-methyl-salicylidene-1,2-diphenylethylenediamine (L5 have been synthesized and characterized by IR spectroscopy and elemental analysis. The sterical hindrance of antitumor drug candidates potentially makes them less susceptible to deactivation by sulphur containing proteins and helping to overcome resistance mechanisms. The interaction of these metal complexes with fish sperm single-stranded DNA (ssDNA was studied electrochemically based on the oxidation signals of guanine and adenine. Differential pulse voltammetry was employed to monitor the DNA interaction in solution by using renewable pencil graphite electrode. The results indicate that ligands with different groups can strongly affect the interaction between [Pt(L] complexes and ssDNA due to sterical hindrances and complex [Pt(L1] has the best interaction with DNA among the five complexes.

  6. Shedding light on the photophysical properties of newly designed platinum(II) complexes by adding substituents on functionalized ligands as highly efficient OLED emitters from a theoretical viewpoint

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jieqiong [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Wang, Li, E-mail: chemwangl@henu.edu.cn [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Wang, Xin [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); He, Chaozheng, E-mail: hecz2013@nynu.edu.cn [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Zhang, Jinglai, E-mail: zhangjinglai@henu.edu.cn [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

    2015-08-01

    The phosphorescent properties of three synthesized and three new designed platinum(II) complexes are focused on in this work. To reveal their structure–property relationships, a density functional theory/time-dependent density functional theory (DFT/TDDFT) investigation is performed on the geometric and electronic structures, absorption and emission spectra. The electroluminescent (EL) properties are evaluated by the ionization potential (IP), electron affinity (EA), and reorganization energy (λ). Furthermore, the radiative rate constant (k{sub r}) is qualitatively elucidated by various factors including the strength of the SOC interaction between the higher-lying singlet excited states (S{sub n}) and the T{sub 1} state, the oscillator strength (f) of the S{sub n} states that can couple with the T{sub 1} state, and the energy separation between the coupled states. A combined analysis of various elements that could affect the phosphorescent efficiency is beneficial to exploring efficient triplet phosphors in OLEDs. Consequently, complexes Pt-1 and 1 would be more suitable blue-emitting phosphorescent materials with balance of EL properties and acceptable quantum yields. - Graphical abstract: Display Omitted - Highlights: • The absorption and phosphorescence spectra of Pt(II) complexes are investigated. • Their Φ{sub em}, IP, EA, and reorganization energy are compared. • Three new Pt(II) complexes are designed.

  7. Synthesis of diorganoplatinum(IV) complexes by the Ssbnd S bond cleavage with platinum(II) complexes

    Science.gov (United States)

    Niroomand Hosseini, Fatemeh; Rashidi, Mehdi; Nabavizadeh, S. Masoud

    2016-12-01

    Reaction of [PtR2(NN)] (R = Me, p-MeC6H4 or p-MeOC6H4; NN = 2,2‧-bipyridine, 4,4‧-dimethyl-2,2‧-bipyridine, 1,10-phenanthroline or 2,9-dimethyl-1,10-phenanthroline) with MeSSMe gives the platinum(IV) complexes cis,trans-[PtR2(SMe)2(NN)]. They are characterized by NMR spectroscopy and elemental analysis. The geometries and the nature of the frontier molecular orbitals of Pt(IV) complexes containing Ptsbnd S bonds are studied by means of the density functional theory.

  8. bis-Nitrile and bis-Dialkylcyanamide Platinum(II) Complexes as Efficient Catalysts for Hydrosilylation Cross-Linking of Siloxane Polymers.

    Science.gov (United States)

    Islamova, Regina M; Dobrynin, Mikhail V; Ivanov, Daniil M; Vlasov, Andrey V; Kaganova, Elena V; Grigoryan, Galina V; Kukushkin, Vadim Yu

    2016-03-05

    cis- and trans-Isomers of the platinum(II) nitrile complexes [PtCl2(NCR)2] (R = NMe2, N(C₅H10), Ph, CH2Ph) were examined as catalysts for hydrosilylation cross-linking of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated poly(dimethylsiloxane-co-ethylhydrosiloxane) producing high quality silicone rubbers. Among the tested platinum species the cis-complexes are much more active catalysts than their trans-congeners and for all studied platinum complexes cis-[PtCl2(NCCH2Ph)2] exhibits the best catalytic activity (room temperature, c = 1.0 × 10(-4) mol/L, τpot-life 60 min, τcuring 6 h). Although cis-[PtCl₂(NCCH2Ph)2] is less active than the widely used Karstedt's catalyst, its application for the cross-linking can be performed not only at room temperature (c = 1.0 × 10(-4) mol/L), but also, more efficiently, at 80 °C (c = 1.0 × 10(-4)-1.0 × 10(-5) mol/L) and it prevents adherence of the formed silicone rubbers to equipment. The usage of the cis- and trans-[PtCl2(NCR)2] complexes as the hydrosilylation catalysts do not require any inhibitors and, moreover, the complexes and their mixtures with vinyl- and trimethylsilyl terminated polysiloxanes are shelf-stable in air. Tested catalysts do not form colloid platinum particles after the cross-linking.

  9. Trans labilization of am(m)ine ligands from platinum(II) complexes by cancer cell extracts.

    Science.gov (United States)

    Kasherman, Yonit; Sturup, Stefan; Gibson, Dan

    2009-03-01

    Cisplatin, cis-[Pt(NH(3))(2)Cl(2)], is an effective anticancer agent in wide clinical use whose efficacy is affected by cellular interactions with sulfur-containing nucleophiles. These interactions can potentially enhance the efficacy of the drug by mediating its delivery to nuclear DNA or inactivate the drug by binding to it irreversibly or by labilizing the NH(3) ligands. Despite the potential importance of trans-labilization reactions in the mechanism of action of the drug, few detailed studies on trans labilization of the ammines have been conducted. We used 2D NMR to show that some trans labilization occurs in proliferating cells and that aqueous extracts of cancer cells labilized 20% of the amine ligands of cis-[PtCl(2)((13)CH(3)NH(2))(2)] after a 12-h incubation. Both low molecular mass nucleophiles (less than 3 kDa) and high molecular mass nucleophiles (more than 3 kDa) labilize the amines with similar efficiency. Studies with model compounds show that thiols and thioethers bind to platinum(II) at similar rates, but thioethers are significantly more efficient at labilizing the am(m)ine at lower pH. N-Acetylcysteine is a more efficient trans-labilizer than glutathione, suggesting that the displacement of the amine proceeds through an associative mechanism. The lag time, the time that elapses from the formation of the Pt-S bond till the release of the amine trans to the sulfur, depends on the pH (for thiols), increasing at lower pH. Quantification of the platinum adducts obtained from incubation of cisplatin with cell extracts indicates that two thirds of the platinum is bound to cellular components with molecular mass greater than 3 kDa.

  10. Decomposition of Intermolecular Interactions in the Crystal Structure of Some Diacetyl Platinum(II Complexes: Combined Hirshfeld, AIM, and NBO Analyses

    Directory of Open Access Journals (Sweden)

    Saied M. Soliman

    2016-12-01

    Full Text Available Intermolecular interactions play a vital role in crystal structures. Therefore, we conducted a topological study, using Hirshfeld surfaces and atom in molecules (AIM analysis, to decompose and analyze, respectively, the different intermolecular interactions in six hydrazone-diacetyl platinum(II complexes. Using AIM and natural bond orbital (NBO analyses, we determined the type, nature, and strength of the interactions. All the studied complexes contain C-H⋯O interactions, and the presence of bond critical points along the intermolecular paths underlines their significance. The electron densities (ρ(r at the bond critical points (0.0031–0.0156 e/a03 fall within the typical range for H-bonding interactions. Also, the positive values of the Laplacian of the electron density (∇2ρ(r revealed the depletion of electronic charge on the interatomic path, another characteristic feature of closed-shell interactions. The ratios of the absolute potential energy density to the kinetic energy density (|V(r|/G(r and ρ(r are highest for the O2⋯H15-N3 interaction in [Pt(COMe2(2-pyCMe=NNH2] (1; hence, this interaction has the highest covalent character of all the O⋯H intermolecular interactions. Interestingly, in [Pt(COMe2(H2NN=CMe-CMe=NNH2] (3, there are significant N-H⋯Pt interactions. Using the NBO method, the second-order interaction energies, E(2, of these interactions range from 3.894 to 4.061 kJ/mol. Furthermore, the hybrid Pt orbitals involved in these interactions are comprised of dxy, dxz, and s atomic orbitals.

  11. Luminescent platinum(II) complexes with functionalized N-heterocyclic carbene or diphosphine selectively probe mismatched and abasic DNA

    OpenAIRE

    Che, CM; Chen, T; To, WP; Zou, T; FUNG, SK; Lok, CN; YANG, C; Cao, B

    2016-01-01

    The selective targeting of mismatched DNA overexpressed in cancer cells is an appealing strategy in designing cancer diagnosis and therapy protocols. Few luminescent probes that specifically detect intracellular mismatched DNA have been reported. Here we used Pt(II) complexes with luminescence sensitive to subtle changes in the local environment and report several Pt(II) complexes that selectively bind to and identify DNA mismatches. We evaluated the complexes' DNA-binding characteristics by ...

  12. Phosphate buffer and salt medium concentrations affect the inactivation of T4 phage by platinum(II) complexes

    DEFF Research Database (Denmark)

    Pedersen, Henrik B.; Josephsen, Jens; Kerszman, Gustaw

    1985-01-01

    -Tris) buffer and HEPES buffer. The phosphate abolishes the antiphage activity of the platinum complexes probably by some sort of complex formation. This together with dimerization reactions qualitatively explains the tailing off of the phage inactivation rate. High concentrations of NaNO3 as the salt medium...

  13. Preparation and Biological Evaluation of Two Novel Platinum(II Complexes Based on the Ligands of Dipicolyamine Bisphosphonate Esters

    Directory of Open Access Journals (Sweden)

    Ling Qiu

    2016-02-01

    Full Text Available Two new platinum(II-based complexes bearing a bone-targeting group were synthesized and characterized. They both have excellent affinity for hydroxyapatite (HA, which is abundant in human bone tissues. Their antitumor activities against five human cancer cell lines (U2OS, A549, HCT116, MDA-MB-231 and HepG2 were evaluated and compared with cisplatin (CDDP. Though the antitumor efficacies of new complexes are lower than that of CDDP, they show higher selectivity against the HepG2 hepatoma cell line than the L02 normal liver cell line. Morphology studies exhibited typical characteristics of cell apoptosis and the cell cycle distribution analysis indicated that the complexes can inhibit cancer cells by inducing cell cycle arrest at the G2/M phase, a similar mechanism of action to CDDP.

  14. Solid solutions of platinum(II) and palladium(II) oxalato-complex salt as precursors of nanoalloys

    Science.gov (United States)

    Zadesenets, A. V.; Asanova, T. I.; Vikulova, E. S.; Filatov, E. Yu.; Plyusnin, P. E.; Baidina, I. A.; Asanov, I. P.; Korenev, S. V.

    2013-03-01

    A solid solution of platinum (II) and palladium (II) oxalato-complex salt, (NH4)2[Pt0.5Pd0.5(C2O4)2]·2H2O, has been synthesized and studied as a precursor for preparing bimetallic PtPd nanoparticles through its thermal decomposition. The smallest homogenous bimetallic PtPd nanoparticles were found to form in hydrogen and helium atmospheres. The annealing temperature and time have low effect on the bimetallic particles size. Comparative analysis of structural and thermal properties of the solid solution and individual Pt, Pd oxalato-complex salts was performed to investigate a mechanism of thermal decomposition of (NH4)2[Pt0.5Pd0.5(C2O4)2]·2H2O. Based on in situ X-ray photoemission spectroscopy investigation it was proposed a mechanism of formation of bimetallic PtPd nanoparticles from the solid-solution oxalato-complex salt during thermal decomposition.

  15. New palladium(II) and platinum(II) 5,5-diethylbarbiturate complexes with 2-phenylpyridine, 2,2'-bipyridine and 2,2'-dipyridylamine: synthesis, structures, DNA binding, molecular docking, cellular uptake, antioxidant activity and cytotoxicity.

    Science.gov (United States)

    Icsel, Ceyda; Yilmaz, Veysel T; Kaya, Yunus; Samli, Hale; Harrison, William T A; Buyukgungor, Orhan

    2015-04-21

    Novel palladium(ii) and platinum(ii) complexes of 5,5-diethylbarbiturate (barb) with 2-phenylpyridine (Hppy), 2,2'-bipyridine (bpy) and 2,2'-dipyridylamine (dpya) have been prepared and characterized by elemental analysis, IR, UV-Vis, NMR and ESI-MS. Single-crystal diffraction measurements show that complex consists of binuclear [Pd2(μ-barb-κN,O)2(ppy-κN,C)2] moieties, while complexes are mononuclear, [M(barb-κN)2(L-κN,N')] (L = bpy or dpya). has a composition of [Pt(dpya-κN,N')2][Ag(barb-κN)2]2·4H2O and was assumed to have a structure of [Pt(barb-κN)(Hppy-κN)(ppy-κN,C)]·3H2O. The complexes were found to exhibit significant DNA binding affinity by a non-covalent binding mode, in accordance with molecular docking studies. In addition, complexes and displayed strong binding with supercoiled pUC19 plasmid DNA. Cellular uptake studies were performed to assess the subcellular localization of the selected complexes. A moderate radical scavenging activity of and was confirmed by DPPH and ABTS tests. Complexes , , and showed selectivity against HT-29 (colon) cell line.

  16. A study of the structure-property relationship of azole-azine based homoleptic platinum(II) complexes and tunability of the photo-physical properties

    Science.gov (United States)

    Ranga Prabhath, Malaviarachchige Rabel

    Owing to superior energy efficiency, Light Emitting Diode (OLED) technology has become considerably commercialised over the last decade. Innovations in this field have been spurred along by the discovery of new molecules with good stability and high emission intensity, followed through by intense engineering efforts. Emissive transition metal complexes are potent molecular emitters as a result of their high quantum efficiencies related to facile intersystem crossing (ISC) between excited-state manifolds (efficient spin orbit coupling (SOC)) and resultant efficient emission from the triplet state (phosphorescence). These also allow rational tuning of the emission wavelengths. Tuning of the ground and excited state energies, and thus emission wavelength of these complexes can be achieved by subtle structural changes in the organic ligands. Pyridyl-triazole ligands have started receiving increasing attention in recent years as strong field ligands that are relatively straightforward to synthesise. In this study we explore the emission tunability of a newly synthesised series of 5-subsituted-Pyridyl-1,2,3-triazole-based ligands and their Pt(II) complexes. Studies have shown, substitution at the triazole moiety is less effective in achieving emission tunability. Alternatively we carried out the substitution at the 5th position of the pyridine ring with a wide range of electronically diverse, donor-acceptor groups (-N(CH3)2, -H, -CHO, -CHC(CN)2). The target ligands were approached through the serial application of the Sonogashira carbon-carbon coupling and the Sharpless copper-catalyzed Huisgen’s 1,3-dipolarcycloaddition procedures. As a result, coarse tunability of excimer emission was observed in thin-films, generating blue-(486 nm), green-(541 nm), orange-(601 nm) and red-(625 nm) luminescence respectively. This “turned-on” substituent effect was accounted for metallophilic Pt—Pt interaction-induced aggregates in the solid state. Excited state calculations

  17. Unusual Circularly Polarized and Aggregation-Induced Near-Infrared Phosphorescence of Helical Platinum(II) Complexes with Tetradentate Salen Ligands.

    Science.gov (United States)

    Song, Jintong; Wang, Man; Zhou, Xiangge; Xiang, Haifeng

    2018-05-17

    A series of chiral and helical Pt II -Salen complexes with 1,1'-binaphthyl linkers were synthesized and characterized. Owing to the restriction of intramolecular motions of central 1,1'-binaphthyls, the complexes exhibit unusual near-infrared aggregation-induced phosphorescence (AIP). The (R)/(S) enantiopure complexes were characterized by X-ray diffraction, circular dichroism spectra, time-dependent density functional theory calculations, and circularly polarized luminescence (CPL). The present work explores the use of tetradentate ligands that can be easily prepared from commercially available enantiopure compounds, and the subsequent preparation of stable CPL-active square planar Pt II complexes with AIP effect that may have interest in many applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Design, synthesis and anticancer activity of diam(m)ine platinum(II) complexes bearing a small-molecular cell apoptosis inducer dichloroacetate.

    Science.gov (United States)

    Liu, Weiping; Jiang, Jing; Xu, Yongping; Hou, Shuqian; Sun, Liping; Ye, Qingsong; Lou, Liguang

    2015-05-01

    Four new diam(m)ine platinum complexes containing the dichloroacetate moiety in 3-dichoroacetoxylcyclobutane-1,1-dicarboxylate as the leaving group were synthesized, characterized by elemental analysis as well as by ESI(+)-MS (electrospray ionization mass spectrometry in positive mode), FT-IR, (1)H- and (13)C-NMR, and evaluated for their in vitro anticancer activity against human lung cancer cell line (A549) and ovarian cancer cell lines (SK-OV-3, SK-OV-3/DDP). Diam(m)ines used in the present study belong to the carriers of six clinically approved platinum drugs. Among the complexes synthesized, complex 2, cis-[Pt(II)(1R,2R-diaminocyclohexane)·(3-dichoroacetoxylcyclobutane-1,1-dicarboxylate)] is the most promising in terms of water solubility and potential of being totally devoid of cross-drug resistance with cisplatin. Therefore, complex 2 was selected for the dichloroacetate release test. The test shows dichloroacetate can be efficiently released from complex 2 under physiological conditions via the hydrolysis of an ester bond bridging the dichloroacetate moiety and platinum pharmacophores together. Our study supports the further evaluation of this complex as a drug candidate. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Prophage induction and mutagenicity of a series of anti-tumour platinum(II) and platinum(IV) co-ordination complexes

    NARCIS (Netherlands)

    Mattern, I.E.; Cocchiarella, L.; Kralingen, C.G. van; Lohman, P.H.M.

    1982-01-01

    Eleven platinum compounds with nitrogen donor ligands, previously tested for anti-tumour activity were studied for induction of prophage lambda and for mutagenicity in the Ames assay, with various strains of Salmonella. The compounds included cis and trans isomers of Pt(II) and Pt(IV) complexes and

  20. ESI-MS studies of the reactions of novel platinum(II) complexes containing O,O'-chelated acetylacetonate and sulfur ligands with selected model proteins.

    Science.gov (United States)

    Marzo, Tiziano; De Pascali, Sandra A; Gabbiani, Chiara; Fanizzi, Francesco P; Messori, Luigi; Pratesi, Alessandro

    2017-08-01

    A group of mixed-ligand Pt(II) complexes bearing acetylacetonate and sulphur ligands were recently developed in the University of Lecce as a new class of prospective anticancer agents that manifested promising pharma-cological properties in preliminary in vitro and in vivo tests. Though modelled on the basis of cisplatin, these Pt(II) complexes turned out to exhibit a profoundly distinct mode of action as they were found to act mainly on non-genomic targets rather than on DNA. Accordingly, we have explored here their reactions with two representative model proteins through an established ESI-MS procedure with the aim to describe their general interaction mechanism with protein targets. A pronounced reactivity with the tested proteins was indeed documented; the nature of the resulting metallodrug-protein interactions could be characterised in depth in the various cases. Preferential binding to protein targets compared to DNA is supported by independent ICP-OES measurements. The implications of these findings are discussed.

  1. Sublethal concentrations of the platinum(II) complex [Pt(O,O'-acac)(gamma-acac)(DMS)] alter the motility and induce anoikis in MCF-7 cells.

    Science.gov (United States)

    Muscella, Antonella; Calabriso, Nadia; Vetrugno, Carla; Urso, Loredana; Fanizzi, Francesco Paolo; De Pascali, Sandra Angelica; Marsigliante, Santo

    2010-07-01

    We showed previously that a new Pt(II) complex ([Pt(O,O'-acac)(gamma-acac)(DMS)]) exerted high and fast apoptotic processes in MCF-7 cells. The objective of this study was to investigate the hypothesis that [Pt(O,O'-acac)(gamma-acac)(DMS)] is also able to exert anoikis and alter the migration ability of MCF-7 cells, and to show some of the signalling events leading to these alterations. Cells were treated with sublethal doses of [Pt(O,O'-acac)(gamma-acac)(DMS)], and the efficiency of colony initiation and anchorage-independent growth was assayed; cell migration was examined by in vitro culture wounding assay. Gelatin zymography for MMP-2 and -9 activities, Western blottings of MMPs, MAPKs, Src, PKC-epsilon and FAK, after [Pt(O,O'-acac)(gamma-acac)(DMS)] treatment, were also performed. Sub-cytotoxic drug concentrations decreased the: (i) anchorage-dependent and -independent growth; (ii) migration ability; and (iii) expression and activity of MMP-2 and MMP-9. [Pt(O,O'-acac)(gamma-acac)(DMS)] provoked the generation of reactive oxygen species (ROS), and the activation of p38MAPK, Src and PKC-epsilon. p38MAPK phosphorylation, cell anoikis and migration due to [Pt(O,O'-acac)(gamma-acac)(DMS)] were blocked by PKC-epsilon inhibition. Furthermore, Src inhibition blocked the [Pt(O,O'-acac)(gamma-acac)(DMS)]-provoked activation of PKC-epsilon, while ROS generation blockage inhibited the activation of Src, and also the decrement of phosphorylated FAK observed in detached [Pt(O,O'-acac)(gamma-acac)(DMS)]-treated cells. Sublethal concentrations of [Pt(O,O'-acac)(gamma-acac)(DMS)] induced anoikis and prevented events leading to metastasis via alterations in cell migration, anchorage independency, stromal interactions and MMP activity. Hence, [Pt(O,O'-acac)(gamma-acac)(DMS)] may be a promising therapeutic agent for preventing growth and metastasis of breast cancer.

  2. and allylsilane platinum(ii)

    African Journals Online (AJOL)

    a

    literature [1, 2]. The products of these reactions are mainly alkenes and hexamethyldisiloxane. ... NMR spectra were obtained on a Perkin-Elmer P-12A spectrometer. ... Samples of complexes 1a-3 were prepared by literature methods [3, 4].

  3. Spectroscopic and biological approach in the characterization of a novel 14-membered [N4] macrocyclic ligand and its palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes.

    Science.gov (United States)

    Rani, Soni; Kumar, Sumit; Chandra, Sulekh

    2014-01-24

    A novel, tetradentate nitrogen donor [N4] macrocyclic ligand, i.e. 3,5,14,16-tetramethyl-2,6,13,17-tetraazatricyclo[12,0,0(7-12)] cosa-1(22),2,5,7,9,11,13,16,18,20-decaene(L), has been synthesized and characterized by elemental analyses, IR, Mass, and (1)H NMR spectral studies. Complexes of Pd(II), Pt(II), Ru(III) and Ir(III) have been prepared and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral and thermal studies. On the basis of molar conductance the complexes may be formulated as [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl and [Ir(L)Cl2]Cl. The complexes are insoluble in most common solvents, including water, ethanol, carbon tetrachloride and acetonitrile, but soluble in DMF/DMSO. The value of magnetic moment indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moment corresponding to one unpaired electron. The magnetic moment of Ru(III) complex is 1.73 B.M. at room temperature. The antimicrobial activities of ligand and its complexes have been screened in vitro, as growth inhibiting agents. The antifungal and antibacterial screening were carried out using Food Poison and Disc Diffusion Method against plant pathogenic fungi and bacteria Alternaria porri, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa respectively. The compounds were dissolved in DMSO to get the required solutions. The required medium used for these activities was PDA and nutrient agar. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Spectroscopic and biological approach in the characterization of a novel 14-membered [N4] macrocyclic ligand and its Palladium(II), Platinum(II), Ruthenium(III) and Iridium(III) complexes

    Science.gov (United States)

    Rani, Soni; Kumar, Sumit; Chandra, Sulekh

    2014-01-01

    A novel, tetradentate nitrogen donor [N4] macrocyclic ligand, i.e. 3,5,14,16-tetramethyl-2,6,13,17-tetraazatricyclo[12,0,07-12] cosa-1(22),2,5,7,9,11,13,16,18,20-decaene(L), has been synthesized and characterized by elemental analyses, IR, Mass, and 1H NMR spectral studies. Complexes of Pd(II), Pt(II), Ru(III) and Ir(III) have been prepared and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral and thermal studies. On the basis of molar conductance the complexes may be formulated as [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl and [Ir(L)Cl2]Cl. The complexes are insoluble in most common solvents, including water, ethanol, carbon tetrachloride and acetonitrile, but soluble in DMF/DMSO. The value of magnetic moment indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moment corresponding to one unpaired electron. The magnetic moment of Ru(III) complex is 1.73 B.M. at room temperature. The antimicrobial activities of ligand and its complexes have been screened in vitro, as growth inhibiting agents. The antifungal and antibacterial screening were carried out using Food Poison and Disc Diffusion Method against plant pathogenic fungi and bacteria Alternaria porri, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa respectively. The compounds were dissolved in DMSO to get the required solutions. The required medium used for these activities was PDA and nutrient agar.

  5. The carbonate complexation of plutonium(IV)

    International Nuclear Information System (INIS)

    Hobart, D.E.; Palmer, P.D.; Newton, T.W.

    1985-01-01

    Plutonium(IV) carbonate complexes are expected to be of particular importance in typical groundwaters at the Yucca Mountain site of the candidate nuclear waste repository being studied by the Nevada Nuclear Waste Storage Investigations Project. The chemistry of these complexes is also important in the areas of nuclear fuel reprocessing and purification, actinide separations, and environmental studies. This report describes initial experiments performed to determine the identity and equilibrium quotients of plutonium(IV) carbonate complexes. These experiments were performed at pH values between 7.2 and 9.6 using a spectrophotometric method. In addition, a brief review of the published literature on Pu(IV) carbonate complexes is presented. Since Pu(IV) exhibits low solubility in the near-neutral pH range, a complex-competition reaction where citrate ligands compete with carbonate ions for the plutonium will be employed. This will permit us to study the pure carbonate system; study the mixed carbonate/citrate system, and confirm and extend the literature work on the pure citrate system. The current experiments have demonstrated the existence of at least three distinct species in the pH region studied. This work will continue in the extended study of the pure citrate system, followed by the investigation of the citrate/carbonate complex/competition reaction. 9 refs., 4 figs., 2 tabs

  6. Mixed ligand complexes of platinum(II) and palladium(II) with cytokinin-derived compounds Bohemine and Olomoucine: X-ray structure of [Pt(BohH+-N7)Cl(3)].9/5H2O [Boh=6-(benzylamino)-2-[(3-(hydroxypropyl)-amino]-9-isopropylpurine, Bohemine

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Maloň, M.; Zatloukal, Marek; Doležal, Karel; Strnad, Miroslav

    2003-01-01

    Roč. 94, č. 4 (2003), s. 307-316 ISSN 0162-0134 R&D Projects: GA ČR GA522/01/0275; GA ČR GA203/00/0152 Institutional research plan: CEZ:AV0Z5038910 Keywords : Platinum(II) * Palladium(II) * Bohemine Subject RIV: CE - Biochemistry Impact factor: 2.343, year: 2003

  7. Preparation and characterization of platinum(II) and (IV) complexes of 1,3-diaminepropane and 1,4-diaminebutane: circumvention of cisplatin resistance and DNA interstrand cross-link formation in CH1cisR ovarian tumor cells.

    Science.gov (United States)

    Alvarez-Valdés, Amparo; Pérez, José Manuel; López-Solera, Isabel; Lannegrand, Raúl; Continente, José Manuel; Amo-Ochoa, Pilar; Camazón, María José; Solans, Xavier; Font-Bardía, Mercè; Navarro-Ranninger, Carmen

    2002-04-25

    The reaction of Pt(dimethyl sulfoxide)(2)CBDCA (CBDCA = 1,1-cyclobutanedicarboxylate) with 1,4-diaminebutane and 1,3-diaminepropane ligands yields, under certain conditions, new [Pt(diamine)(2)]CBDCA complexes (1a,b), where the CBDCA ligand has been removed from the coordination sphere of the platinum atom by the diamine ligand, instead of forming the expected [Pt(diamine)CBDCA] complexes (1'a,b). The structure of complexes 1a and 1'b was solved by X-ray diffraction. Complex 1a crystallizes in the orthorhombic system, in the noncentrosymmetric C222 space group, with unit cell parameters: a = 20.053(2) A; b = 8.655(2) A, c = 5.711(3) A; V = 991.2(6) A(3); delta (calcd) = 1.627 mg/m(3); and R = 0.050. The Pt atom displays an unexpected distorted tetrahedral coordination with a N-Pt-N inner bond angle equal to 81(2) degrees for N atoms of the same 1,3-propanediamine ligand and a N-Pt-N bond angle for different ligands equal to 135.4(9) degrees. Complex 1'b crystallizes in the monoclinic system, in the centrosymmetric P2(1)/c space group, with unit cell parameters: a = 6.007(2) A; b = 15.336(4) A, c = 13.232(5) A; beta = 101.90(3) degrees; V = 1192.8(7) A(3); delta (calcd) = 2.369 mg/m(3); and R = 0.067. Cytotoxicity data show that of all the synthesized compounds, only complexes 1'a and 1'b exhibit remarkable cytotoxic properties. Thus, in contrast with carboplatin (cis-diammine-1,1-cyclobutane dicarboxilatoplatinum(II)), compounds 1'a and 1'b, which also contain the CBDCA ligand, are able to circumvent cisplatin (cis-diamminedichloroplatinum(II)) resistance in several tumor cells. Moreover, after 24 h of incubation of CH1cisR ovarian tumor cells with 10 microM of compounds 1'a and 1'b, the level of DNA interstrand cross-links (ICLs) induced by compounds 1'a and 1'b is 3.3 and 3.8 times higher, respectively, than that of carboplatin and 3.5 and 4.0 times higher, respectively, than that of cisplatin. Interestingly, under the same conditions, the intracellular

  8. Carbon-hydrogen-related complexes in Si

    Science.gov (United States)

    Kolkovsky, Vl.; Stübner, R.; Gwozdz, K.; Weber, J.

    2018-04-01

    Several deep level transient spectroscopy (DLTS) peaks (E42, E65, E75, E90, E262, and H180) are observed in n- and p-type Czochralski-grown Si samples subjected to hydrogenation by a dc H plasma treatment. The concentration of the defects is found to be proportional to the carbon and hydrogen content in our samples. The analysis of the depth profiles performed in Si samples hydrogenated by wet chemically etching shows that all these defects contain a single H atom. E65 and E75 appear only in samples with a high oxygen content which shows that oxygen is a constituent of these defects. The analysis of the enhancement of the emission rate of the defects with electric field shows that E65, E75, E90, and E262 are single acceptors whereas E42 is a double acceptor. The presence of a barrier for hole capture (about 53 meV) can explain the absence of the enhancement of the emission rate of H180, which can be attributed to a single acceptor state. From a comparison with theory, we assign E90 to CH1BC, E42 (E262) to CH1AB, and H180 to CH1Td. The similarity of the electrical properties of E65 and E75 to those of E90 suggest that E65 and E75 may originate from the CH1BC defect with an oxygen atom in its nearest neighborhood. Our results on the CH-related complexes give a conclusive explanation of some previously reported controversial experimental data.

  9. Study of new complexes of uranium and comba radical. I.- Complexes defective in sodium carbonate

    International Nuclear Information System (INIS)

    Vera Palomino, J.; Galiano Sedano, J. A.; Parellada Bellod, R.; Bellido Gonzalez, A.

    1975-01-01

    Some complexes formed in presence of defect of sodium carbonate with respect to the stoichiometric ratio (U): (C0 3 ) = 1:3 are studied. This ratio corresponds to the main complex which is responsible for the uranium extraction with CDMBAC organic solutions and from U(VI) aqueous solutions with an excess of sodium carbonate. (Author) 10 refs

  10. Defect complexes in carbon and boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG

    2012-05-01

    Full Text Available The effect of defect complexes on the stability, structural and electronic properties of single-walled carbon nanotubes and boron nitride nanotubes is investigated using the ab initio pseudopotential density functional method implemented...

  11. Platinum Group Thiophenoxyimine Complexes: Syntheses,Crystallographic and Computational Studies of Structural Properties

    Energy Technology Data Exchange (ETDEWEB)

    Krinsky, Jamin L.; Arnold, John; Bergman, Robert G.

    2006-10-03

    Monomeric thiosalicylaldiminate complexes of rhodium(I) and iridium(I) were prepared by ligand transfer from the homoleptic zinc(II) species. In the presence of strongly donating ligands, the iridium complexes undergo insertion of the metal into the imine carbon-hydrogen bond. Thiophenoxyketimines were prepared by non-templated reaction of o-mercaptoacetophenone with anilines, and were complexed with rhodium(I), iridium(I), nickel(II) and platinum(II). X-ray crystallographic studies showed that while the thiosalicylaldiminate complexes display planar ligand conformations, those of the thiophenoxyketiminates are strongly distorted. Results of a computational study were consistent with a steric-strain interpretation of the difference in preferred ligand geometries.

  12. Enhancement of thermal stability of silver(I) acetylacetonate by platinum(II) acetylacetonate

    Czech Academy of Sciences Publication Activity Database

    Křenek, T.; Kovářík, T.; Pola, M.; Jakubec, Ivo; Bezdička, Petr; Bastl, Zdeněk; Pokorná, Dana; Urbanová, Markéta; Galíková, Anna; Pola, Josef

    2013-01-01

    Roč. 554, FEB (2013), s. 1-7 ISSN 0040-6031 Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:67985858 Keywords : thermal gravimetric analysis * differential scanning calorimetry * silver(I) acetylacetonate * platinum(II) acetylacetonate * enhancement of thermal stability Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 2.105, year: 2013

  13. Analysis and application of classification methods of complex carbonate reservoirs

    Science.gov (United States)

    Li, Xiongyan; Qin, Ruibao; Ping, Haitao; Wei, Dan; Liu, Xiaomei

    2018-06-01

    There are abundant carbonate reservoirs from the Cenozoic to Mesozoic era in the Middle East. Due to variation in sedimentary environment and diagenetic process of carbonate reservoirs, several porosity types coexist in carbonate reservoirs. As a result, because of the complex lithologies and pore types as well as the impact of microfractures, the pore structure is very complicated. Therefore, it is difficult to accurately calculate the reservoir parameters. In order to accurately evaluate carbonate reservoirs, based on the pore structure evaluation of carbonate reservoirs, the classification methods of carbonate reservoirs are analyzed based on capillary pressure curves and flow units. Based on the capillary pressure curves, although the carbonate reservoirs can be classified, the relationship between porosity and permeability after classification is not ideal. On the basis of the flow units, the high-precision functional relationship between porosity and permeability after classification can be established. Therefore, the carbonate reservoirs can be quantitatively evaluated based on the classification of flow units. In the dolomite reservoirs, the average absolute error of calculated permeability decreases from 15.13 to 7.44 mD. Similarly, the average absolute error of calculated permeability of limestone reservoirs is reduced from 20.33 to 7.37 mD. Only by accurately characterizing pore structures and classifying reservoir types, reservoir parameters could be calculated accurately. Therefore, characterizing pore structures and classifying reservoir types are very important to accurate evaluation of complex carbonate reservoirs in the Middle East.

  14. Catalytic Copolymerization of Ethene and Carbon Monoxide on Nickel Complexes.

    Science.gov (United States)

    Domhöver, Bernd; Kläui, Wolfgang; Kremer-Aach, Andreas; Bell, Ralf; Mootz, Dietrich

    1998-11-16

    Can palladium be replaced by nickel? For the industrial copolymerization of carbon monoxide and ethene a palladium catalyst is used which cannot be recovered-a cheaper procedure would be desirable. The presented complex 1 is the first structurally characterized nickel compound which does not polymerize ethene but a mixture from carbon monoxide and ethene unter mild conditions to give a perfectly alternating polyketone. © 1998 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  15. Complex terrain influences ecosystem carbon responses to temperature and precipitation

    Science.gov (United States)

    Reyes, W. M.; Epstein, H. E.; Li, X.; McGlynn, B. L.; Riveros-Iregui, D. A.; Emanuel, R. E.

    2017-08-01

    Terrestrial ecosystem responses to temperature and precipitation have major implications for the global carbon cycle. Case studies demonstrate that complex terrain, which accounts for more than 50% of Earth's land surface, can affect ecological processes associated with land-atmosphere carbon fluxes. However, no studies have addressed the role of complex terrain in mediating ecophysiological responses of land-atmosphere carbon fluxes to climate variables. We synthesized data from AmeriFlux towers and found that for sites in complex terrain, responses of ecosystem CO2 fluxes to temperature and precipitation are organized according to terrain slope and drainage area, variables associated with water and energy availability. Specifically, we found that for tower sites in complex terrain, mean topographic slope and drainage area surrounding the tower explained between 51% and 78% of site-to-site variation in the response of CO2 fluxes to temperature and precipitation depending on the time scale. We found no such organization among sites in flat terrain, even though their flux responses exhibited similar ranges. These results challenge prevailing conceptual framework in terrestrial ecosystem modeling that assumes that CO2 fluxes derive from vertical soil-plant-climate interactions. We conclude that the terrain in which ecosystems are situated can also have important influences on CO2 responses to temperature and precipitation. This work has implications for about 14% of the total land area of the conterminous U.S. This area is considered topographically complex and contributes to approximately 15% of gross ecosystem carbon production in the conterminous U.S.

  16. High-temperature carbonates in the Stillwater Complex, Montana, USA

    Science.gov (United States)

    Aird, H. M.; Boudreau, A. E.

    2012-12-01

    The processes involved in the petrogenesis of the sulphide-hosted platinum-group-element (PGE) deposits of the Stillwater Complex are controversial, with theories ranging from the purely magmatic to those involving an aqueous fluid. To further constrain these models, we have been examining the trace phase assemblages in rocks away from the ore zones. High-temperature carbonates have been observed in association with sulphide minerals below the platiniferous J-M Reef of the Stillwater Complex. The carbonate assemblage consists of dolomite with exsolved calcite and is found in contact with sulphide minerals: chalcopyrite and pyrrhotite in the Peridotite Zone; and pyrrhotite with pentlandite, pyrite and chalcopyrite in Gabbronorite I of the Lower Banded Series. The minimal silicate alteration and the lack of greenschist minerals in association with the mineral assemblage are consistent with a high-temperature origin for the carbonates. The calcite-dolomite geothermometer [1] yields a minimum formation temperature of ~900°C for the unmixed assemblages. A reaction rim surrounds the carbonate-sulphide assemblages, showing an alteration of the host orthopyroxene to a more Ca-enriched, Fe-depleted composition. This is consistent with diffusive exchange between carbonates and pyroxenes at high temperatures, mediated by an aqueous fluid. The highly variable molar MnO/FeO ratios in both the high-temperature carbonates and their associated altered pyroxene rims also imply their interaction with a fluid. The carbonate assemblages are consistent with Stillwater fluid inclusion studies [2], showing that fluids comprising coexisting Cl-rich brine and carbonic fluid were trapped in pegmatitic quartz at 700-715°C, some of which also contained "accidental" calcite inclusions. The high Cl-content of apatite [3] found below the platiniferous J-M Reef is further evidence that a Cl-rich fluid was migrating through the rocks beneath the Reef. Carbonates have been shown to be stabilized

  17. Linking aboveground net primary productivity to soil carbon and dissolved organic carbon in complex terrain

    Science.gov (United States)

    F.S. Peterson; K. Lajtha

    2013-01-01

    Factors influencing soil organic matter (SOM) stabilization and dissolved organic carbon (DOC) content in complex terrain, where vegetation, climate, and topography vary over the scale of a few meters, are not well understood. We examined the spatial correlations of lidar and geographic information system-derived landscape topography, empirically measured soil...

  18. Carbon-13 NMR characterization of actinyl(VI) carbonate complexes in aqueous solution

    International Nuclear Information System (INIS)

    Clark, D.L.; Hobart, D.E.; Palmer, P.D.; Sullivan, J.C.; Stout, B.E.

    1992-01-01

    The uranyl(VI) carbonate system has been re-examined using 13 C NMR of 99.9% 13 C-enriched U VI O 2 ( 13 CO 3 ) 3 4- in millimolar concentrations. By careful control of carbonate ion concentration, we have confirmed the existence of the trimer, and observed dynamic equilibrium between the monomer and the timer. In addition, the ligand exchange reaction between free and coordinated carbonate on Pu VI O 2 ( 13 CO 3 ) 3 4- and Am VI O 2 ( 13 CO 3 ) 3 4- systems has been examined by variable temperature 13 C NMR line-broadening techniques 13 C NMR line-broadening techniques. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was written to allow for experimental determination of ligand exchange parameters for paramagnetic actinide complexes. Preliminary Eyring analysis has provided activation parameters of ΔG double-dagger 295 = 56 kJ/M, ΔH double-dagger = 38 kJ/M, and ΔS double-dagger = -60 J/M-K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl (VI) carbonate complex self-exchange reaction. Experiments for determination of the activation parameters for the americium (VI) carbonate system are in progress

  19. Covalent functionalization of carbon nanotubes with tetramanganese complexes

    International Nuclear Information System (INIS)

    Meyer, Carola; Frielinghaus, Robert; Saelhoff, Anna-Katharina; Schneider, Claus M.; Besson, Claire; Floetotto, Henrik; Koegerler, Paul; Houben, Lothar

    2012-01-01

    We present first results on the covalent chemical functionalization of single-walled carbon nanotubes with polynuclear {Mn 4 } coordination complexes. Raman spectra prove that the reaction can only be achieved for tubes which have been oxidized to create carboxylic groups. HRTEM is used to show that the reaction can be carried out directly on a substrate as well. Analysis of the D/G intensity ratio for different oxidation times shows that it is possible to reduce the amount of defects created. This is important for the future application of this material in transport devices. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Binding of dioxouranium(VI) and platinum(II) to ribonuclease-S

    Energy Technology Data Exchange (ETDEWEB)

    Marzotto, A [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

    1976-12-01

    The preferred binding sites of RNase-S to dioxouranium(VI) and platinum(II) has been determined by Wyckoff et al., (J.Biol.Chem., v242, 1967, p.3749; ibid p.3984; ibid v245, 1970, p.305) elaborating protein and of heavy-atom derivatives reported by Wyckoff and coworkers. The major sites are exposed at the surface of the protein molecule and are not directly involved in the biological properties; the coordination geometry of the groups bound to the metal ions have been examined in comparison with model compounds.

  1. Reduction of uranyl carbonate and hydroxyl complexes and neptunyl carbonate complexes studied with chemical-electrochemical methods and rixs spectroscopy

    International Nuclear Information System (INIS)

    Butorin, Sergei; Nordgren, Joseph; Ollila, Kaija; Albinsson, Yngve; Werme, Lars

    2003-10-01

    Sweden and Finland plan to dispose of spent fuel from commercial nuclear power plants in deep underground repositories sited in granitic rocks. The fuel assemblies will be placed in canisters consisting of an outer corrosion-resistant copper shell with an inner cast iron insert that gives mechanical strength and reduces void space in the canister. The canister will be placed in a disposal borehole lined with compacted bentonite blocks. After sealing of the borehole, groundwater seepage will saturate the bentonite. The water flow path and transport mechanism between the host rock and the canister will be via diffusion through the swollen bentonite. Any oxygen trapped in the repository will be consumed by reaction with the host rock, pyrite in the bentonite and through microbial activity, giving long-term conditions with low redox potentials. Under these conditions, uranium dioxide - the matrix of unirradiated fuel - is a stable phase. This reducing near-field environment can upset by radiolysis of water caused by the radioactivity of the fuel, which after a few hundred years will be primarily alpha activity. Radiolysis of water produces equal amounts of oxidising and reducing species, but the reducing species produced by alpha radiolysis is molecular hydrogen, which is expected to be far less reactive than the produced oxidising species, H 2 O 2 . Alpha radiolysis could create locally oxidising conditions close to the fuel surface and oxidise the U(IV) in the uranium dioxide fuel to the more soluble U(VI) oxidation state. Furthermore, the solubility of U(VI) is enhanced in the presence of bicarbonate/carbonate by the formation of strong anionic uranyl carbonate complexes. This increase in solubility can amount to 4 to 5 orders of magnitude depending on the composition of the groundwater in contact with the fuel. The other tetravalent actinides in the fuel, Np and Pu, also have higher solubilities when oxidised beyond 4 + to neptunyl and plutonyl species. Once these

  2. Complexity Analysis of Carbon Market Using the Modified Multi-Scale Entropy

    Directory of Open Access Journals (Sweden)

    Jiuli Yin

    2018-06-01

    Full Text Available Carbon markets provide a market-based way to reduce climate pollution. Subject to general market regulations, the major existing emission trading markets present complex characteristics. This paper analyzes the complexity of carbon market by using the multi-scale entropy. Pilot carbon markets in China are taken as the example. Moving average is adopted to extract the scales due to the short length of the data set. Results show a low-level complexity inferring that China’s pilot carbon markets are quite immature in lack of market efficiency. However, the complexity varies in different time scales. China’s carbon markets (except for the Chongqing pilot are more complex in the short period than in the long term. Furthermore, complexity level in most pilot markets increases as the markets developed, showing an improvement in market efficiency. All these results demonstrate that an effective carbon market is required for the full function of emission trading.

  3. A Bimetallic Aluminium(Salphen) Complex for the Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide.

    Science.gov (United States)

    Wu, Xiao; North, Michael

    2017-01-10

    A bimetallic aluminium(salphen) complex is reported as a sustainable, efficient and inexpensive catalyst for the synthesis of cyclic carbonates from epoxides and carbon dioxide. In the presence of this complex and tetrabutylammonium bromide, terminal and internal epoxides reacted at 50 °C and 10 bar carbon dioxide pressure to afford their corresponding cyclic carbonates in yields of 50-94 % and 30-71 % for terminal and internal cyclic carbonates, respectively. Mechanistic studies using deuterated epoxides and an analogous monometallic aluminium(salphen) chloride complex support a mechanism for catalysis by the bimetallic complex, which involves intramolecular cooperative catalysis between the two aluminium centres. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Building complex carbon skeletons with ethynyl[2.2]paracyclophanes

    Directory of Open Access Journals (Sweden)

    Ina Dix

    2014-08-01

    Full Text Available Ethynyl[2.2]paracyclophanes are shown to be useful substrates for the preparation of complex, highly unsaturated carbon frameworks. Thus both the pseudo-geminal- 2 and the pseudo-ortho-diethynylcyclophane 4 can be dimerized by Glaser coupling to the respective dimers 9/10 and 11/12. Whereas the former isomer pair could not be separated so far, the latter provided the pure diastereomers after extensive column chromatography/recrystallization. Isomer 11 is chiral and could be separated on a column impregnated with cellulose tris(3,5-dimethylphenylcarbamate. The bridge-extended cyclophane precursor 18 furnished the ring-enlarged cyclophanes 19 and 20 on Glaser–Hay coupling. Cross-coupling of 4 and the planar building block 1,2-diethynylbenzene (1 yielded the chiral hetero dimer 22 as the main product. An attempt to prepare the biphenylenophane 27 from the triacetylene 24 by CpCo(CO2-catalyzed cycloisomerization resulted in the formation of the cyclobutadiene Co-complex 26. Besides by their usual spectroscopic and analytical data, the new cyclophanes 11, 12, 19, 20, 22, and 26 were characterized by X-ray structural analysis.

  5. Energy transfer from natural photosynthetic complexes to single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wiwatowski, Kamil [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Dużyńska, Anna; Świniarski, Michał [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Szalkowski, Marcin [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Zdrojek, Mariusz; Judek, Jarosław [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Mackowski, Sebastian, E-mail: mackowski@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Wroclaw Research Center EIT+, Stablowicka 147, Wroclaw (Poland); Kaminska, Izabela [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland)

    2016-02-15

    Combination of fluorescence imaging and spectroscopy results indicates that single-walled carbon nanotubes are extremely efficient quenchers of fluorescence emission associated with chlorophylls embedded in a natural photosynthetic complex, peridinin-chlorophyll-protein. When deposited on a network of the carbon nanotubes forming a thin film, the emission of the photosynthetic complexes diminishes almost completely. This strong reduction of fluorescence intensity is accompanied with dramatic shortening of the fluorescence lifetime. Concluding, such thin films of carbon nanotubes can be extremely efficient energy acceptors in structures involving biologically functional complexes. - Highlights: • Fluorescence imaging of carbon nanotube - based hybrid structure. • Observation of efficient energy transfer from chlorophylls to carbon nanotubes.

  6. Thermal decomposition of vinyl- and allylsilane platinum(II ...

    African Journals Online (AJOL)

    CHCH2SiMe3)], K[(acac)PtCl(CH2=CHSiMe3)] and [PtCl(CH2=CHCH2SiMe3)]2, were examined. All complexes were found to be stable at room temperature but they decomposed without melting above about 90 oC. The allylsilane complex ...

  7. Biogeochemical stability and reactions of iron-organic carbon complexes

    Science.gov (United States)

    Yang, Y.; Adhikari, D.; Zhao, Q.; Dunham-Cheatham, S.; Das, K.; Mejia, J.; Huang, R.; Wang, X.; Poulson, S.; Tang, Y.; Obrist, D.; Roden, E. E.

    2017-12-01

    Our core hypothesis is that the degradation rate of soil organic carbon (OC) is governed by the amount of iron (Fe)-bound OC, and the ability of microbial communities to utilize OC as an energy source and electron shuttle for Fe reduction that in turn stimulates reductive release of Fe-bound labile dissolved OC. This hypothesis is being systematically evaluated using model Fe-OC complexes, natural soils, and microcosm system. We found that hematite-bound aliphatic C was more resistant to reduction release, although hematite preferred to sorb more aromatic C. Resistance to reductive release represents a new mechanism that aliphatic soil OC was stabilized by association with Fe oxide. In other studies, pyrogenic OC was found to facilitate the reduction of hematite, by enhancing extracellular electron transport and sorbing Fe(II). For ferrihydrite-OC co-precipitates, the reduction of Fe and release of OC was closely governed by the C/Fe ratio in the system. Based on the XPS, XANES and XAFS analysis, the transformation of Fe speciation was heterogeneous, depending on the conformation and composition of Fe-OC complexes. For natural soils, we investigated the quantity, characteristics, and reactivity of Fe-bound OC in soils collected from 14 forests in the United States. Fe-bound OC contributed up to 57.8% of total OC in the forest soils. Under the anaerobic conditions, the reduction of Fe was positively correlated to the electron accepting capacity of OC. Our findings highlight the closely coupled dynamics of Fe and OC, with broad implications on the turnover of OC and biogeochemical cycles of Fe.

  8. Joint Optimal Production Planning for Complex Supply Chains Constrained by Carbon Emission Abatement Policies

    OpenAIRE

    He, Longfei; Xu, Zhaoguang; Niu, Zhanwen

    2014-01-01

    We focus on the joint production planning of complex supply chains facing stochastic demands and being constrained by carbon emission reduction policies. We pick two typical carbon emission reduction policies to research how emission regulation influences the profit and carbon footprint of a typical supply chain. We use the input-output model to capture the interrelated demand link between an arbitrary pair of two nodes in scenarios without or with carbon emission constraints. We design optim...

  9. Electronic and electrochemical properties of platinum(II) and platinum-mercury-carboxylato complexes containing 2-Me2NCH2C6H4, 2,6-(Me2NCH2)2C6H3- and 2-Me2NC6H4CH2 - ligands

    NARCIS (Netherlands)

    Koten, G. van; Ploeg, A.F.M.J. van der; Schmitz, J.E.J.; Linden, J.G.M. van der

    1982-01-01

    The organoplatinum(II) compounds [{2, 6-(Me{2}NCH{2}){2}C{6}H{3}}PtBr] and cis-[(C-N){2}Pt] (C-N = 2-Me{2}NCH{2}C{6}H{4}, 2-Me{2}NC{6}H{4}CH{2}) can be chemically irreversibly oxidized in the potential range 1.00 to 1.35 V vs. an Ag/AgCl electrode, whereas the organoplatinum@?mercury complexes

  10. Stability and kinetics of uranyl ion complexation by macrocycles in propylene carbonate

    International Nuclear Information System (INIS)

    Fux, P.

    1984-06-01

    A thermodynamic study of uranyl ion complexes formation with different macrocyclic ligands was realized in propylene carbonate as solvent using spectrophotometric and potentiometric techniques. Formation kinetics of two UO 2 complexes: a crown ether (18C6) and a coronand (22) was studied by spectrophotometry in propylene carbonate with addition of tetraethylammonium chlorate 0.1M at 25 0 C. Possible structures of complexes in solution are discussed [fr

  11. Thermodynamic and electrochemical properties of some rare earth cryptates and related complexes in propylene carbonate

    International Nuclear Information System (INIS)

    Loufouilou, E.L.

    1986-03-01

    The stability of trivalent lanthanide complexes with [1]-cryptand 22 and [2]-cryptands 222 and 211 and also tris (3.6- dioxa heptyl) amine (TDHA) is studied in propylene carbonate solution by potentiometry with Ag + as an auxiliary cation. Complexation enthalpies and entropies are determined for other complexes of some trivalent lanthanides (La, Er, Pr and Eu) with ligands 222, 221, 211, 22, 21, 18C6 and TDHA. [1]- and [2]- crytands are complexing agents more powerful than TDHA and crown-ethers 15C6 and 18C6. For ligands containing nitrogen complexe stability increase with RE atomic number but decrease for crown-ethers. In propylene carbonate complexes are stabilized by enthalpic effects, entropic contribution is variable. Polarographic reduction of samarium cryptate with ligand 222, 221 and 22 in propylene carbonate is reversible as in more solvating solvents water and methanol. Mixed complexes are formed with chlorides and this cryptate system is more difficult to reduce [fr

  12. Unsaturated carbone and allenylidene ruthenium complexes from alkynes

    International Nuclear Information System (INIS)

    Bozek, Yu.L.; Diznev, P.A.

    1995-01-01

    The author's studies aimed at activation of terminal alkynes by metal complexes, reactivity patterns and selective preparations of unsaturated carbene, allenylidene and cumulenylidene derivatives of (arene)ruthenium complexes are reviewed. 48 refs

  13. Diiridium Bimetallic Complexes Function as a Redox Switch To Directly Split Carbonate into Carbon Monoxide and Oxygen.

    Science.gov (United States)

    Chen, Tsun-Ren; Wu, Fang-Siou; Lee, Hsiu-Pen; Chen, Kelvin H-C

    2016-03-23

    A pair of diiridium bimetallic complexes exhibit a special type of oxidation-reduction reaction that could directly split carbonate into carbon monoxide and molecular oxygen via a low-energy pathway needing no sacrificial reagent. One of the bimetallic complexes, Ir(III)(μ-Cl)2Ir(III), can catch carbonato group from carbonate and reduce it to CO. The second complex, the rare bimetallic complex Ir(IV)(μ-oxo)2Ir(IV), can react with chlorine to release O2 by the oxidation of oxygen ions with synergistic oxidative effect of iridium ions and chlorine atoms. The activation energy needed for the key reaction is quite low (∼20 kJ/mol), which is far less than the dissociation energy of the C═O bond in CO2 (∼750 kJ/mol). These diiridium bimetallic complexes could be applied as a redox switch to split carbonate or combined with well-known processes in the chemical industry to build up a catalytic system to directly split CO2 into CO and O2.

  14. Can uranyl complexes encapsulate to carbon nanotubes? A ...

    Indian Academy of Sciences (India)

    K SRINIVASU

    We find that uranyl-aqua complex ([UO2(H2O)5]2+) binds stronger as compared to uranyl-hydroxo-complex .... until the maximum Hellmann–Feynman force on each atom ..... porters and near-infrared agents for selective cancer cell.

  15. Participation of Co-Ligands in Electronic Transitions of Platinum(II) Diazabutadiene Complexes

    Czech Academy of Sciences Publication Activity Database

    Klein, A.; Slageren van, J.; Záliš, Stanislav

    2002-01-01

    Roč. 41, č. 20 (2002), s. 5216-5225 ISSN 0020-1669 R&D Projects: GA MŠk ME 439; GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : molecular photochemical device * resonance Raman-spectra * alpha-diimine ligands Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.950, year: 2002

  16. Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

    DEFF Research Database (Denmark)

    Arnosti, Carol; Finke, Niko; Larsen, Ole

    2005-01-01

    of activity that it fueled, its soluble nature, and its relatively high (50%) carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity to react rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar to observations made......Complex substrates are degraded in anoxic sediments by the concerted activities of diverse microbial communities. To explore the effects of substrate complexity on carbon transformations in permanently cold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high...... which they were derived. Although Spirulina and Iso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydrate content), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbon was respired, despite the initial burst...

  17. Phosphorus and nitrogen-containing carbons obtained by the carbonization of conducting polyaniline complex with phosphites

    Czech Academy of Sciences Publication Activity Database

    Bober, Patrycja; Trchová, Miroslava; Morávková, Zuzana; Kovářová, Jana; Vulić, I.; Gavrilov, N.; Pašti, I. A.; Stejskal, Jaroslav

    2017-01-01

    Roč. 246, 20 August (2017), s. 443-450 ISSN 0013-4686 R&D Projects: GA ČR(CZ) GA16-02787S Institutional support: RVO:61389013 Keywords : carbonization * conducting polymer * nitrogen-containing carbon Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 4.798, year: 2016

  18. Spontaneous Resolution and Carbonation of Chiral Benzyllithium Complexes

    DEFF Research Database (Denmark)

    Lennartson, Anders; Sundberg, Jonas; Wiklund, Tove

    2010-01-01

    In search for new examples of absolute asymmetric synthesis (AAS), chiral α-substituted benzyllithium complexes have been prepared. While [Li(phet)(pmdta)] (1) (phet = 1-phenylethyl, pmdta = N,N,N′,N″,N″-pentamethyldiethylenetriamine) affords only racemic crystals, a promising candidate for AAS w...

  19. Two Iron Complexes as Homogeneous and Heterogeneous Catalysts for the Chemical Fixation of Carbon Dioxide.

    Science.gov (United States)

    Karan, Chandan Kumar; Bhattacharjee, Manish

    2018-04-16

    Two new bimetallic iron-alkali metal complexes of amino acid (serine)-based reduced Schiff base ligand were synthesized and structurally characterized. Their efficacy as catalysts for the chemical fixation of carbon dioxide was explored. The heterogeneous version of the catalytic reaction was developed by the immobilization of these homogeneous bimetallic iron-alkali metal complexes in an anion-exchange resin. The resin-bound complexes can be used as recyclable catalysts up to six cycles.

  20. Unprecedented Carbonato Intermediates in Cyclic Carbonate Synthesis Catalysed by Bimetallic Aluminium(Salen) Complexes.

    Science.gov (United States)

    Castro-Osma, José A; North, Michael; Offermans, Willem K; Leitner, Walter; Müller, Thomas E

    2016-04-21

    The mechanism by which [Al(salen)]2 O complexes catalyse the synthesis of cyclic carbonates from epoxides and carbon dioxide in the absence of a halide cocatalyst has been investigated. Density functional theory (DFT) studies, mass spectrometry and (1) H NMR, (13) C NMR and infrared spectroscopies provide evidence for the formation of an unprecedented carbonato bridged bimetallic aluminium complex which is shown to be a key intermediate for the halide-free synthesis of cyclic carbonates from epoxides and carbon dioxide. Deuterated and enantiomerically-pure epoxides were used to study the reaction pathway. Based on the experimental and theoretical results, a catalytic cycle is proposed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Investigation of different-ligand complexes of holmium and erbium with NTA and carbonate ion

    International Nuclear Information System (INIS)

    Nazarenko, N.A.; Bel'tyukova, S.V.; Poluehktov, N.S.

    1979-01-01

    Found out have been the optimum conditions for the formation of the lantanides (Ln) multiligand complexes with the nitriletriacetic acid (NTA) and the carbonate-ion. It has been established that the components correlation in complex compounds is equal to 1:1:1. Computed have been the values of the oscillator forces of the absorption bands, that conform to the ''supersensitive'' migration of the multiligand complexes, It is shown that the increment in the oscillator forces, the induced entering of one carbonate-ion into the Ln-NTA complex molecule conforms to about 1/4 of the oscillator forces increment during the migration from the aquo ion to the [Ln(CO 3 ) 4 ] 5- complex carbonaceous ion

  2. Evidence of different stoichiometries for the limiting carbonate complexes of lanthanides(3)

    International Nuclear Information System (INIS)

    Philippini, V.

    2007-12-01

    Two stoichiometries have been proposed by different laboratories to interpret measurements on the limiting carbonate complexes of An 3+ and Ln 3+ cations. The study of the solubility of double carbonates (AlkLn(CO 3 ) 2 ,xH 2 O) in concentrated carbonate solutions at room temperature and high ionic strengths has shown that on the one hand the lightest lanthanides (La and Nd) form Ln(CO 3 ) 4 5- whereas the heaviest (Eu and Dy) form Ln(CO 3 ) 3 3- in the studied chemical conditions, and on the other hand, that the kinetics of precipitation of double carbonates depends on the alkali metal and the lanthanide ions. The existence of two stoichiometries for the limiting carbonate complexes was confirmed by capillary electrophoresis hyphenated to an inductively coupled plasma mass spectrometer (CE-ICP-MS), used to extend the study to the whole series of lanthanides (except Ce, Pm and Yb). Two behaviours have been put forward comparing the electrophoretic mobilities: La to Tb form Ln(CO 3 ) 4 5- while Dy to Lu form Ln(CO 3 ) 3 3- . Measurements by time resolved laser fluorescence spectroscopy (TRLFS) on Eu(III) indicate small variations of the geometry of Eu(CO 3 ) 3 3- complex, specially with Cs + . Although analogies are currently used among the 4f-block trivalent elements, different aqueous speciations are evidenced in concentrated carbonate solutions across the lanthanide series. (author)

  3. Ubiquinol-cytochrome c reductase (Complex III) electrochemistry at multi-walled carbon nanotubes/Nafion modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    Pelster, Lindsey N.; Minteer, Shelley D.

    2012-01-01

    Highlights: ► The electron transport chain is important to the understanding of metabolism in the living cell. ► Ubiquinol-cytochrome c reductase is a membrane bound complex of the electron transport chain (Complex III). ► The paper details the first bioelectrochemical characterization of ubiquinol-cytochrome c reductase at an electrode. - Abstract: Electron transport chain complexes are critical to metabolism in living cells. Ubiquinol-cytochrome c reductase (Complex III) is responsible for carrying electrons from ubiquinol to cytochrome c, but the complex has not been evaluated electrochemically. This work details the bioelectrochemistry of ubiquinol-cytochrome c reductase of the electron transport chain of tuber mitochondria. The characterization of the electrochemistry of this enzyme is investigated in carboxylated multi-walled carbon nanotube/tetrabutyl ammonium bromide-modified Nafion ® modified glassy carbon electrodes by cyclic voltammetry. Increasing concentrations of cytochrome c result in a catalytic response from the active enzyme in the nanotube sandwich. The experiments show that the enzyme followed Michaelis–Menten kinetics with a K m for the immobilized enzyme of 2.97 (±0.11) × 10 −6 M and a V max of 6.31 (±0.82) × 10 −3 μmol min −1 at the electrode, but the K m and V max values decreased compared to the free enzyme in solution, which is expected for immobilized redox proteins. This is the first evidence of ubiquinol-cytochrome c reductase bioelectrocatalysis.

  4. Chromatographic behavior of carbonate complexes of lanthanides and of thorium in alumina

    International Nuclear Information System (INIS)

    Tomida, E.K.

    1977-01-01

    The chromatographic behavior of some rare earth elements and thorium on alumina is studied in order to evaluate the possibility of separation from concentration of trace rare earths from high-purity thorium compounds. The effect of some factors on complex thorium carbonate formation and the extent of thorium solubility in sodium and potassium carbonate solutions investigated. The sorption of rare earth elements and thoriuum on alumina from alkali carbonate solution is observed, despite the reports that alumina acts as a cation exchanger in alkali media and that thorium and rare earths form stable anionic carbonate complexes. The formation of these elements between alumina and potassium carbonate solutions is studied as a function of pH, carbonate concentration and metal ion concentration. Also the elution of rare earths from alumina is studied and the best results are obtained with mineral acids and EDTA plus alkali carbonate solutions. The effect of some parameters as column aging, mixed solvents, column treatment with organic solvents, temperature, aluant concentration is investigated. Attempting to understand this sorption mechanism, some experiments with strongly basic anion exchanger and cation exchangers of strongly acid and weakly acid type are accomplished. It is observed that there are significant differences, in some conditions, between the behavior of rare earths and of thorium, pointing our the possibility of separation of one lanthanide from others and of these from thorium [pt

  5. Range of engineering-geological properties for some carbonate rock complexes for Balkan peninsula

    International Nuclear Information System (INIS)

    Jovanovski, Milorad; Shpago, Azra; Peshevski, Igor

    2010-01-01

    The Carbonate Rock masses are a geological media with extremely complex states and properties, which has a certain influences on the mechanical and hydraulic behavior during construction and exploitation of engineering structures. Practical aspects of the problem analysis arise from the fact that the areas of Bosnia and Herzegovina, Macedonia and the entire Balkans is characterized by presence of wide areas covered with carbonate complexes, where large number of complex engineering structures have been, or shall be constructed in the future. In this context, their engineering-geological modeling is still a practical and scientific challenge. The analysis of engineering- geological properties is one of the main steps in forming of analytical and geotechnical models for complex rock structures. This article gives a data about the range for these properties, according to the results from an extensive investigation program. Some original correlations and testing results are given and they are compared with some published relations from the world. (Author)

  6. Fe(III) mobilisation by carbonate in low temperature environments: Study of the solubility of ferrihydrite in carbonate media and the formation of Fe(III) carbonate complexes

    International Nuclear Information System (INIS)

    Grivé, Mireia; Duro, Lara; Bruno, Jordi

    2014-01-01

    Graphical abstract: - Highlights: • We have determined thermodynamic stabilities of Fe(III)-carbonate species. • We have determined the effect of those species on the solubility of ferrihydrite. • Results. • Highlight the importance of two Fe(III)-carbonate: FeOHCO 3 and Fe(CO 3 ) 3 3− . - Abstract: The linkage between the iron and the carbon cycles is of paramount importance to understand and quantify the effect of increased CO 2 concentrations in natural waters on the mobility of iron and associated trace elements. In this context, we have quantified the thermodynamic stability of mixed Fe(III) hydroxo-carbonate complexes and their effect on the solubility of Fe(III) oxihydroxides. We present the results of carefully performed solubility measurements of 2-line ferrihydrite in the slightly acidic to neutral–alkaline pH ranges (3.8–8.7) under constant pCO 2 varying between (0.982–98.154 kPa) at 25 °C. The outcome of the work indicates the predominance of two Fe(III) hydroxo carbonate complexes FeOHCO 3 and Fe(CO 3 ) 3 3− , with formation constants log * β° 1,1,1 = 10.76 ± 0.38 and log β° 1,0,3 = 24.24 ± 0.42, respectively. The solubility constant for the ferrihydrite used in this study was determined in acid conditions (pH: 1.8–3.2) in the absence of CO 2 and at T = (25 ± 1) °C, as log * K s,0 = 1.19 ± 0.41. The relative stability of the Fe(III)-carbonate complexes in alkaline pH conditions has implications for the solubility of Fe(III) in CO 2 -rich environments and the subsequent mobilisation of associated trace metals that will be explored in subsequent papers

  7. Surface complexation of carbonate on goethite: IR spectroscopy, structure & charge distribution

    NARCIS (Netherlands)

    Hiemstra, T.; Rahnemaie, R.; Riemsdijk, van W.H.

    2004-01-01

    The adsorption of carbonate on goethite has been evaluated, focussing on the relation between the structure of the surface complex and corresponding adsorption characteristics, like pH dependency and proton co-adsorption. The surface structure of adsorbed CO3-2 has been assessed with (1) a

  8. Room temperature synthesis of protonated layered titanate sheets using peroxo titanium carbonate complex solution.

    Science.gov (United States)

    Sutradhar, Narottam; Sinhamahapatra, Apurba; Pahari, Sandip Kumar; Bajaj, Hari C; Panda, Asit Baran

    2011-07-21

    We report the synthesis of peroxo titanium carbonate complex solution as a novel water-soluble precursor for the direct synthesis of layered protonated titanate at room temperature. The synthesized titanates showed excellent removal capacity for Pb(2+) and methylene blue. Based on experimental observations, a probable mechanism for the formation of protonated layered dititanate sheets is also discussed.

  9. Spectrofluorimetric characterization and study for the determination of rare earth carbonate complexes

    International Nuclear Information System (INIS)

    Dantas, E.S.K.; Abrao, A.

    1982-01-01

    Some rare earths exhibit fluorescence in acid solution (HC1, H 2 SO 4 or HC10 4 ) when irradiated with ultraviolet radiation; however, analytical application of this property has not been proposed due to the lack of sensitivity resulted from the weakness of the fluorescence transitions. The rare earths are soluble in alkali carbonate solutions, forming anionic carbonate complexes (TR(CO 3 ) sup(n-) sub(x)); some of them have stronger absorption bands than those obtained in acid media. Using this property, the characterization and determination of the six rare earths which fluoresce in carbonate solution has been studied. The excitation and emission wavelengths are (in nm): Sm (406, 596); Eu (280,612); Gd (272,312); Tb (240,542); Dy (350, 576) and Tm (360, 450). Although Ce-III is highly fluorescent in acid media, when in carbonate solution it is easily oxidized to Ce-IV which does not fluoresce neither in acid nor in carbonate solutions. The other rare earths, although soluble in carbonate solution, do not fluoresce in this medium. A comparison is made, between the fluorescence of the fluorescing lanthanides, in acid and carbonate media. The precision and accuracy of this method, the detection limit of all rare earths studied and the mutual interference of some of them is also discussed. The method will be applied to the analytical control of the separation and purification of individual rare earths, now under development. (Author) [pt

  10. Carbonic anhydrase activity of integral-functional complexes of thylakoid membranes of spinach chloroplasts

    Directory of Open Access Journals (Sweden)

    A. V. Semenihin

    2015-06-01

    Full Text Available Isolated thylakoid membranes were disrupted by treatment with nonionic detergents digitonin or dodecyl maltoside. Solubilized polypeptide complexes were separated by native gel charge shift electrophoresis. The position of ATP-synthase complex and its isolated catalytic part (CF1 within gel was determined using the color reaction for ATPase activity. Due to the presence of cytochromes, the red band in unstained gels corresponded to the cytochrome b6f complex. Localization of the cytochrome b6f complex, ATP synthase and coupling CF1 in the native gel was confirmed by their subunit composition determined after SDS-electrophoretic analysis. Carbonic anhydrase (CA activity in polypeptide zones of PS II, cytochrome b6f complex, and ATP-synthase CF1 was identified in native gels using indicator bromothymol blue. CA activity of isolated CF1 in solution was determined by infrared gas analysis as the rate of bicarbonate dehydration. The water-soluble acetazolamide, an inhibitor of CA, unlike lipophilic ethoxyzolamide inhibited CA activity of CF1. Thus, it was shown for the first time that ATP-synthase has a component which is capable of catalyzing the interconversion of forms of carbonic acid associated with proton exchange. The data obtained suggest the presence of multiple forms of carbonic anhydrase in the thylakoid membranes of spinach chloroplasts and confirm their involvement in the proton transfer to the ATP synthase.

  11. Extraction of cobalt ion from textile using a complexing macromolecular surfactant in supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Chirat, Mathieu; Ribaut, Tiphaine; Clerc, Sebastien; Lacroix-Desmazes, Patrick; Charton, Frederic; Fournel, Bruno

    2013-01-01

    Cobalt ion under the form of cobalt nitrate is removed from a textile lab coat using supercritical carbon dioxide extraction. The process involves a macromolecular additive of well-defined architecture, acting both as a surfactant and a complexing agent. The extraction efficiency of cobalt reaches 66% when using a poly(1,1,2,2-tetrahydroperfluoro-decyl-acrylate-co-vinyl-benzylphosphonic diacid) gradient copolymer in the presence of water at 160 bar and 40 C. The synergy of the two additives, namely the copolymer and water which are useless if used separately, is pointed out. The potential of the supercritical carbon dioxide process using complexing macromolecular surfactant lies in the ability to modulate the complexing unit as a function of the metal as well as the architecture of the surface-active agent for applications ranging for instance from nuclear decontamination to the recovery of strategic metals. (authors)

  12. Formation of carbonato and hydroxo complexes in the reaction of platinum anticancer drugs with carbonate.

    Science.gov (United States)

    Di Pasqua, Anthony J; Centerwall, Corey R; Kerwood, Deborah J; Dabrowiak, James C

    2009-02-02

    The second-generation Pt(II) anticancer drug carboplatin is here shown to react with carbonate, which is present in blood, interstitial fluid, cytosol, and culture medium, to produce platinum-carbonato and -hydroxo complexes. Using [(1)H-(15)N] HSQC NMR and (15)N-labeled carboplatin, we observe that cis-[Pt(CBDCA-O)(OH)(NH(3))(2)](-), cis-[Pt(OH)(2)(NH(3))(2)], cis-[Pt(CO(3))(OH)(NH(3))(2)](-), and what may be cis-[Pt(CO(3))(NH(3))(2)] are produced when 1 is allowed to react in 23.8 mM carbonate buffer. When (15)N-labeled carboplatin is allowed to react in 0.5 M carbonate buffer, these platinum species, as well as other hydroxo and carbonato species, some of which may be dinuclear complexes, are produced. Furthermore, we show that the carbonato species cis-[Pt(CO(3))(OH)(NH(3))(2)](-) is also produced when cisplatin is allowed to react in carbonate buffer. The study outlines the conditions under which carboplatin and cisplatin form carbonato and aqua/hydroxo species in carbonate media.

  13. The effect of carbon and boron on the accumulation of vacancy-oxygen complexes in silicon

    International Nuclear Information System (INIS)

    Akhmetov, V.D.; Bolotov, V.V.

    1980-01-01

    By means of IR-absorption measurements the dose dependencies of the concentrations of vacancy-oxygen complexes (VO), interstitial oxygen atoms (Osub(I)), substitutional carbon atoms (Csub(S)) and interstitial carbon-oxygen complexes (Csub(I)Osub(I)) in n- and p-type silicon irradiated with 1.1 MeV electrons have been investigated. The observed increase of the production rate of VO-complexes with the rise of carbon and boron atoms concentrations (these impurities act as sinks for silicon interstitial atoms) has been explained in terms of annihilation of the vacancies and interstitials on the oxygen atoms. The results obtained show that boron atoms are more effective sinks than carbon atoms for the interstitial silicon atoms. That seems to be connected not only with the higher probability of boron injection into interstitial position but also with the further capture of interstitial silicon atoms on the interstitial boron, i.e. with the interstitial cluster formation. (author)

  14. Transformation of Graphitic and Amorphous Carbon Dust to Complex Organic Molecules in a Massive Carbon Cycle in Protostellar Nebulae

    Science.gov (United States)

    Nuth, Joseph A., III; Johnson, Natasha M.

    2012-01-01

    relatively inert carbonaceous dust from the ISM into the vital organic precursors to life such as amino acids and sugars intimately mixed with dust and ice in primitive planetesimals. Since the number of carbon atoms entering the Solar Nebula as dust exceeds the number of atoms entering the nebula as oxide grains. the formation of large quantities of complex organic molecules may represent the largest single chemical cycle in the nebula.

  15. Joint Optimal Production Planning for Complex Supply Chains Constrained by Carbon Emission Abatement Policies

    Directory of Open Access Journals (Sweden)

    Longfei He

    2014-01-01

    Full Text Available We focus on the joint production planning of complex supply chains facing stochastic demands and being constrained by carbon emission reduction policies. We pick two typical carbon emission reduction policies to research how emission regulation influences the profit and carbon footprint of a typical supply chain. We use the input-output model to capture the interrelated demand link between an arbitrary pair of two nodes in scenarios without or with carbon emission constraints. We design optimization algorithm to obtain joint optimal production quantities combination for maximizing overall profit under regulatory policies, respectively. Furthermore, numerical studies by featuring exponentially distributed demand compare systemwide performances in various scenarios. We build the “carbon emission elasticity of profit (CEEP” index as a metric to evaluate the impact of regulatory policies on both chainwide emissions and profit. Our results manifest that by facilitating the mandatory emission cap in proper installation within the network one can balance well effective emission reduction and associated acceptable profit loss. The outcome that CEEP index when implementing Carbon emission tax is elastic implies that the scale of profit loss is greater than that of emission reduction, which shows that this policy is less effective than mandatory cap from industry standpoint at least.

  16. Quantum mechanical calculation of aqueuous uranium complexes: carbonate, phosphate, organic and biomolecular species

    Directory of Open Access Journals (Sweden)

    Jha Prashant

    2009-08-01

    Full Text Available Abstract Background Quantum mechanical calculations were performed on a variety of uranium species representing U(VI, U(V, U(IV, U-carbonates, U-phosphates, U-oxalates, U-catecholates, U-phosphodiesters, U-phosphorylated N-acetyl-glucosamine (NAG, and U-2-Keto-3-doxyoctanoate (KDO with explicit solvation by H2O molecules. These models represent major U species in natural waters and complexes on bacterial surfaces. The model results are compared to observed EXAFS, IR, Raman and NMR spectra. Results Agreement between experiment and theory is acceptable in most cases, and the reasons for discrepancies are discussed. Calculated Gibbs free energies are used to constrain which configurations are most likely to be stable under circumneutral pH conditions. Reduction of U(VI to U(IV is examined for the U-carbonate and U-catechol complexes. Conclusion Results on the potential energy differences between U(V- and U(IV-carbonate complexes suggest that the cause of slower disproportionation in this system is electrostatic repulsion between UO2 [CO3]35- ions that must approach one another to form U(VI and U(IV rather than a change in thermodynamic stability. Calculations on U-catechol species are consistent with the observation that UO22+ can oxidize catechol and form quinone-like species. In addition, outer-sphere complexation is predicted to be the most stable for U-catechol interactions based on calculated energies and comparison to 13C NMR spectra. Outer-sphere complexes (i.e., ion pairs bridged by water molecules are predicted to be comparable in Gibbs free energy to inner-sphere complexes for a model carboxylic acid. Complexation of uranyl to phosphorus-containing groups in extracellular polymeric substances is predicted to favor phosphonate groups, such as that found in phosphorylated NAG, rather than phosphodiesters, such as those in nucleic acids.

  17. Study by magnetic resonance and relaxation of carbon 13 of some paramagnetic coordination complexes

    International Nuclear Information System (INIS)

    Ronfard-Haret, Jean-Claude

    1977-01-01

    This research thesis reports the study of coordination complexes by using NMR. After a brief recall of the theoretical background required for the processing of experimental data (hyper-fine coupling and magnetic resonance, spin density distribution, chemical displacement, dipolar, scalar and electronic relaxation), the author describes the conditions in which experiments have been performed and presents measurement methods (pulsed nuclear magnetic resonance, relaxation time measurement, determination of hyper-fine coupling constants, spectrometers and reactants). The next chapters address the study of different coordination complexes: [(pyridine-N-oxide) 2 Ni(acetylacetonate) 2 ], carbon 13 in alkyl-anilines-Ni II, complexation of 1- and 2-aminonaphthalene by transition ions, complexation of pyridine-N-oxide by the nickel Ni ++ ion in presence of water

  18. A diketiminate-bound diiron complex with a bridging carbonate ligand

    Science.gov (United States)

    Sadique, Azwana R.; Brennessel, William W.; Holland, Patrick L.

    2009-01-01

    Reduction of carbon dioxide by a diiron(I) complex gives μ-carbonato-κ3 O:O′,O′′-bis­{[2,2,6,6-tetra­methyl-3,5-bis­(2,4,6-triisopropyl­phenyl)heptane-2,5-diiminate(1−)-κ2 N,N′]iron(II)} toluene disolvate, [Fe2(C41H65N)2(CO3)]·2C7H8, a diiron(II) species with a bridging carbonate ligand. The asymmetric unit contains one diiron complex and two cocrystallized toluene solvent mol­ecules that are distributed over three sites, one with atoms in general positions and two in crystallographic sites. Both FeII atoms are η2-coordinated to diketiminate ligands, but η1- and η2-coordinated to the bridging carbonate ligand. Thus, one FeII center is three-coordinate and the other is four-coordinate. The bridging carbonate ligand is nearly perpendicular to the iron–diketiminate plane of the four-coordinate FeII center and parallel to the plane of the three-coordinate FeII center. PMID:19407402

  19. Characterization and determination of the stability constant of lanthanide complexes with carbonates

    International Nuclear Information System (INIS)

    Bidoglio, G.; Marcandalli, B.

    1983-01-01

    The stability constants of Europium (III) complexes with carbonate and bicarbonate ions are measured at 22 0 C and at 0.5M ionic strength. Solvent extraction with 1.3-diphenyl 1.3-propanedione 5x10 -2 M in benzene is studied. The distribution between the organic and aqueous phases is determined by radioactive tracers. The limits of the spectrophotometric method and of the solubility in the evaluation of this type of complex are evidenced, mainly in the concentration range useful in geochemistry. Some results obtained with Nd and Am 241 are also given

  20. Low-Frequency Carbon Recombination Lines in the Orion Molecular Cloud Complex

    Science.gov (United States)

    Tremblay, Chenoa D.; Jordan, Christopher H.; Cunningham, Maria; Jones, Paul A.; Hurley-Walker, Natasha

    2018-05-01

    We detail tentative detections of low-frequency carbon radio recombination lines from within the Orion molecular cloud complex observed at 99-129 MHz. These tentative detections include one alpha transition and one beta transition over three locations and are located within the diffuse regions of dust observed in the infrared at 100 μm, the Hα emission detected in the optical, and the synchrotron radiation observed in the radio. With these observations, we are able to study the radiation mechanism transition from collisionally pumped to radiatively pumped within the H ii regions within the Orion molecular cloud complex.

  1. Age, extent and carbon storage of the central Congo Basin peatland complex.

    Science.gov (United States)

    Dargie, Greta C; Lewis, Simon L; Lawson, Ian T; Mitchard, Edward T A; Page, Susan E; Bocko, Yannick E; Ifo, Suspense A

    2017-02-02

    Peatlands are carbon-rich ecosystems that cover just three per cent of Earth's land surface, but store one-third of soil carbon. Peat soils are formed by the build-up of partially decomposed organic matter under waterlogged anoxic conditions. Most peat is found in cool climatic regions where unimpeded decomposition is slower, but deposits are also found under some tropical swamp forests. Here we present field measurements from one of the world's most extensive regions of swamp forest, the Cuvette Centrale depression in the central Congo Basin. We find extensive peat deposits beneath the swamp forest vegetation (peat defined as material with an organic matter content of at least 65 per cent to a depth of at least 0.3 metres). Radiocarbon dates indicate that peat began accumulating from about 10,600 years ago, coincident with the onset of more humid conditions in central Africa at the beginning of the Holocene. The peatlands occupy large interfluvial basins, and seem to be largely rain-fed and ombrotrophic-like (of low nutrient status) systems. Although the peat layer is relatively shallow (with a maximum depth of 5.9 metres and a median depth of 2.0 metres), by combining in situ and remotely sensed data, we estimate the area of peat to be approximately 145,500 square kilometres (95 per cent confidence interval of 131,900-156,400 square kilometres), making the Cuvette Centrale the most extensive peatland complex in the tropics. This area is more than five times the maximum possible area reported for the Congo Basin in a recent synthesis of pantropical peat extent. We estimate that the peatlands store approximately 30.6 petagrams (30.6 × 10 15  grams) of carbon belowground (95 per cent confidence interval of 6.3-46.8 petagrams of carbon)-a quantity that is similar to the above-ground carbon stocks of the tropical forests of the entire Congo Basin. Our result for the Cuvette Centrale increases the best estimate of global tropical peatland carbon stocks by

  2. C,N-2-[(Dimethylamino)methyl]phenylplatinum Complexes Functionalized with C60 as Macromolecular Building Blocks

    NARCIS (Netherlands)

    Koten, G. van; Meijer, M.D.; Wolf, E. de; Lutz, M.H.; Spek, A.L.; Klink, G.P.M. van

    2001-01-01

    The application of platinum(II) complexes based on the N,N-dimethylbenzylamine ligand (abbreviated as H-C,N) in macromolecular synthesis was demonstrated. Two cationic C,N-platinum moieties were linked with a 4,4'-bipyridine bridge, giving [{C6H4(CH2NMe2)-2-Pt(PPh3)}2(4,4'-bpy)](BF4)2 (2), the

  3. New insight into the ternary complexes of uranyl carbonate in seawater.

    Science.gov (United States)

    Beccia, M R; Matara-Aho, M; Reeves, B; Roques, J; Solari, P L; Monfort, M; Moulin, C; Den Auwer, C

    2017-11-01

    Uranium is naturally present in seawater at trace levels and may in some cases be present at higher concentrations, due to anthropogenic nuclear activities. Understanding uranium speciation in seawater is thus essential for predicting and controlling its behavior in this specific environmental compartment and consequently, its possible impact on living organisms. The carbonato calcic complex Ca 2 UO 2 (CO 3 ) 3 was previously identified as the main uranium species in natural seawater, together with CaUO 2 (CO 3 ) 3 2- . In this work, we further investigate the role of the alkaline earth cation in the structure of the ternary uranyl-carbonate complexes. For this purpose, artificial seawater, free of Mg 2+ and Ca 2+ , using Sr 2+ as a spectroscopic probe was prepared. Combining TRLIF and EXAFS spectroscopy, together with DFT and theoretical thermodynamic calculations, evidence for the presence of Sr alkaline earth counter ion in the complex structure can be asserted. Furthermore, data suggest that when Ca 2+ is replaced by Sr 2+ , SrUO 2 (CO 3 ) 3 2- is the main complex in solution and it occurs with the presence of at least one monodentate carbonate in the uranyl coordination sphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Synthesis and Characterization of Hexahapto-Chromium Complexes of Single-Walled Carbon Nanotubes

    KAUST Repository

    Kalinina, Irina

    2016-12-17

    This chapter employs purified pristine single-walled carbon nanotubes (SWNTs) and octadecylaminefunctionalized-SWNTs. These SWNTs are employed for investigate the potential of the SWNT sidewall to function as a hexahapto ligand for chromium (Cr), with in-depth characterization of the products using some of the techniques, such as thermogravimetric analysis (TGA), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS). Purified electric arc (EA)-produced SWNTs (P2-SWNT) and octadecylaminefunctionalized SWNTs were obtained from Carbon Solutions, Inc. The TEM images show the removal of the Cr particles from the outer surface of the SWNT bundles in the SWNT-Cr complexes after decomplexation; Cr attachment to the surface of the as-prepared complexes (η6-SWNT)Cr(CO)3 and (η6-SWNT-CONH(CH2)17CH3)Cr(CO)3 is clearly evident. The positions of the bands in the Raman spectra of SWNTs are sensitive to doping and thus the chapter examines the effect of complexation of the Cr(CO)3 and Cr(η6-benzene) units on the position of the G and 2D bands in the (η6-SWNT)Cr(CO)3 and (η6-SWNT)Cr(η6-benzene) complexes.

  5. Heterologous Production of an Energy-Conserving Carbon Monoxide Dehydrogenase Complex in the Hyperthermophile Pyrococcus furiosus

    Directory of Open Access Journals (Sweden)

    Gerrit Jan Schut

    2016-01-01

    Full Text Available Carbon monoxide (CO is an important intermediate in anaerobic carbon fixation pathways in acetogenesis and methanogenesis. In addition, some anaerobes can utilize CO as an energy source. In the hyperthermophilic archaeon Thermococcus onnurineus, which grows optimally at 80°C, CO oxidation and energy conservation is accomplished by a respiratory complex encoded by a 16-gene cluster containing a carbon monoxide dehydrogenase, a membrane-bound [NiFe]-hydrogenase and a Na+/H+ antiporter module. This complex oxidizes CO, evolves CO2 and H2, and generates a Na+ motive force that is used to conserve energy by a Na+-dependent ATP synthase. Herein we used a bacterial artificial chromosome to insert the 13.2 kb gene cluster encoding the CO-oxidizing respiratory complex of T. onnurineus into the genome of the heterotrophic archaeon, Pyrococcus furiosus, which grows optimally at 100°C. P. furiosus is normally unable to utilize CO, however, the recombinant strain readily oxidized CO and generated H2 at 80°C. Moreover, CO also served as an energy source and allowed the P. furiosus strain to grow with a limiting concentration of sugar or with peptides as the carbon source. Moreover, CO oxidation by P. furiosus was also coupled to the re-utilization, presumably for biosynthesis, of acetate generated by fermentation. The functional transfer of CO utilization between Thermococcus and Pyrococcus species demonstrated herein is representative of the horizontal gene transfer of an environmentally-relevant metabolic capability. The transfer of CO utilizing, hydrogen-producing genetic modules also has applications for biohydrogen production and a CO-based industrial platform for various thermophilic organisms.

  6. Subsurface Permian reef complexes of southern Tunisia: Shelf carbonate setting and paleogeographic implications

    Science.gov (United States)

    Zaafouri, Adel; Haddad, Sofiene; Mannaî-Tayech, Beya

    2017-05-01

    2-D seismic reflection sections, borehole data as well as published and unpublished data have been investigated to reconstruct the paleogeography of southern Tunisia during Middle to Late Permian times. Paleogeographical reconstruction based on the integration of petroleum well data and 2-D seismic facies interpretation shows three main depositional areas with very contrasting sedimentary pile. These are 1) a subsiding basin; 2) an outer shelf carbonate, and 3) an inner shelf carbonate. Based on typical electric responses of reef buildups to seismic wave, we shall urge that during Middle Permian times, the outer carbonate shelf was subject of reef barrier development. Lithology evidences from core samples show that reef framework correspond mainly to fossiliferous limestone and dolomite. The WNW-ESE recognized reef barrier led between latitudes 33° 10‧ 00″N and 33° 20‧ 00″N. The Tebaga of Medenine outcrop constitutes the northern-edge of this barrier. Westward it may be extended to Bir Soltane area whereas its extension eastward is still to be determined. Biogenic buildups took place preferentially over faulted Carboniferous and lower Paleozoic paleohighs resulting likely from the Hercynian orogeny. The subsiding basin is located north of Tebaga of Medenine outcrop where Upper Permian sedimentary sequence is made entirely of 4000 m deep marine green silty shale facies. These are ascribed to unorganized and chaotic reflectors. Inner carbonate shelf facies succession corresponds to a typical interbedding of shallow marine carbonate deposits, shale, dolomite, and anhydrite inducing parallel-layered of strong amplitude and good continuity reflectors. Also within the inner carbonate shelf patch reef or reef pinnacles have been identified based on their seismic signature particularly their low vertical development as compared to reef complexes. Southward, towards Sidi Toui area, the Upper Permian depositional sequence thins out and bears witness of land

  7. CARBON DIOXIDE INFLUENCE ON THE THERMAL FORMATION OF COMPLEX ORGANIC MOLECULES IN INTERSTELLAR ICE ANALOGS

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradoff, V.; Fray, N.; Bouilloud, M.; Cottin, H. [LISA Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR CNRS 7583, Université Paris Est Créteil (UPEC), Université Paris Diderot (UPD), Institut Pierre Simon Laplace, Labex ESEP, Paris (France); Duvernay, F.; Chiavassa, T., E-mail: vvinogradoff@mnhn.fr [PIIM, Laboratoire de Physique des Interactions Ioniques et Moléculaires, Université Aix-Marseille, UMR CNRS 7345, Marseille (France)

    2015-08-20

    Interstellar ices are submitted to energetic processes (thermal, UV, and cosmic-ray radiations) producing complex organic molecules. Laboratory experiments aim to reproduce the evolution of interstellar ices to better understand the chemical changes leading to the reaction, formation, and desorption of molecules. In this context, the thermal evolution of an interstellar ice analogue composed of water, carbon dioxide, ammonia, and formaldehyde is investigated. The ice evolution during the warming has been monitored by IR spectroscopy. The formation of hexamethylenetetramine (HMT) and polymethylenimine (PMI) are observed in the organic refractory residue left after ice sublimation. A better understanding of this result is realized with the study of another ice mixture containing methylenimine (a precursor of HMT) with carbon dioxide and ammonia. It appears that carbamic acid, a reaction product of carbon dioxide and ammonia, plays the role of catalyst, allowing the reactions toward HMT and PMI formation. This is the first time that such complex organic molecules (HMT, PMI) are produced from the warming (without VUV photolysis or irradiation with energetic particles) of abundant molecules observed in interstellar ices (H{sub 2}O, NH{sub 3}, CO{sub 2}, H{sub 2}CO). This result strengthens the importance of thermal reactions in the ices’ evolution. HMT and PMI, likely components of interstellar ices, should be searched for in the pristine objects of our solar system, such as comets and carbonaceous chondrites.

  8. CARBON DIOXIDE INFLUENCE ON THE THERMAL FORMATION OF COMPLEX ORGANIC MOLECULES IN INTERSTELLAR ICE ANALOGS

    International Nuclear Information System (INIS)

    Vinogradoff, V.; Fray, N.; Bouilloud, M.; Cottin, H.; Duvernay, F.; Chiavassa, T.

    2015-01-01

    Interstellar ices are submitted to energetic processes (thermal, UV, and cosmic-ray radiations) producing complex organic molecules. Laboratory experiments aim to reproduce the evolution of interstellar ices to better understand the chemical changes leading to the reaction, formation, and desorption of molecules. In this context, the thermal evolution of an interstellar ice analogue composed of water, carbon dioxide, ammonia, and formaldehyde is investigated. The ice evolution during the warming has been monitored by IR spectroscopy. The formation of hexamethylenetetramine (HMT) and polymethylenimine (PMI) are observed in the organic refractory residue left after ice sublimation. A better understanding of this result is realized with the study of another ice mixture containing methylenimine (a precursor of HMT) with carbon dioxide and ammonia. It appears that carbamic acid, a reaction product of carbon dioxide and ammonia, plays the role of catalyst, allowing the reactions toward HMT and PMI formation. This is the first time that such complex organic molecules (HMT, PMI) are produced from the warming (without VUV photolysis or irradiation with energetic particles) of abundant molecules observed in interstellar ices (H 2 O, NH 3 , CO 2 , H 2 CO). This result strengthens the importance of thermal reactions in the ices’ evolution. HMT and PMI, likely components of interstellar ices, should be searched for in the pristine objects of our solar system, such as comets and carbonaceous chondrites

  9. X-ray Absorption Spectroscopy Identifies Calcium-Uranyl-Carbonate Complexes at Environmental Concentrations

    International Nuclear Information System (INIS)

    Kelly, Shelly D.; Kemner, Kenneth M.; Brooks, Scott C.

    2007-01-01

    Current research on bioremediation of uranium-contaminated groundwater focuses on supplying indigenous metal-reducing bacteria with the appropriate metabolic requirements to induce microbiological reduction of soluble uranium(VI) to poorly soluble uranium(IV). Recent studies of uranium(VI) bioreduction in the presence of environmentally relevant levels of calcium revealed limited and slowed uranium(VI) reduction and the formation of a Ca-UO2-CO3 complex. However, the stoichiometry of the complex is poorly defined and may be complicated by the presence of a Na-UO2-CO3 complex. Such a complex might exist even at high calcium concentrations, as some UO2-CO3 complexes will still be present. The number of calcium and/or sodium atoms coordinated to a uranyl carbonate complex will determine the net charge of the complex. Such a change in aqueous speciation of uranium(VI) in calcareous groundwater may affect the fate and transport properties of uranium. In this paper, we present the results from X-ray absorption fine structure (XAFS) measurements of a series of solutions containing 50 lM uranium(VI) and 30 mM sodium bicarbonate, with various calcium concentrations of 0-5 mM. Use of the data series reduces the uncertainty in the number of calcium atoms bound to the UO2-CO3 complex to approximately 0.6 and enables spectroscopic identification of the Na-UO2-CO3 complex. At nearly neutral pH values, the numbers of sodium and calcium atoms bound to the uranyl triscarbonate species are found to depend on the calcium concentration, as predicted by speciation calculations

  10. Adsorption of some metal complexes derived from acetyl acetone on activated carbon and purolite S-930

    Directory of Open Access Journals (Sweden)

    Salam A.H. Al-Ameri

    2014-12-01

    Full Text Available A new Schiff base (HL derived from condensation of p-anisidine and acetyl acetone has been prepared and used as a chelating ligand to prepare Cr(III, Mn(II, Co(II, Ni(II and Cu(II complexes. The study of the nature of these complexes formed in ethanol solution following the mole ratio method (2:1, L:M gave results which were compared successfully with these obtained from isolated solid state studies. These studies revealed that the complexes having square planner geometry of the type (ML2, M = Co(II, Ni(II and Cu(II, and octahedral geometry of the type [CrIIIL2(H2O2]Cl and [MNIIL2(H2O2]. The adsorption studies of three complexes Cr(III, Mn(II, and Co(II on activated carbon, H and Na-forms of purolite S-930 resin show high adsorption percentage for Cr(III on purolite S-930 due to ion exchange interaction compared with high adsorption of neutral Mn(II, Co(II complexes on activated charcoal. Linear plot of log Qe versus log Ce showed that the adsorption isotherm of these three complexes on activated carbon, H and Na-forms of purolite S-930 surface obeys Freundlich isotherm and was similar to S-curve type according to Giles classification which investigates heterogeneous adsorption. The regression values indicate that the adsorption data for these complexes fitted well within the Freundlich isothermal plots for the concentration studied. The accuracy and precision of the concentration measurements of these complexes were determined by preparing standard laboratory samples, the results show relative error ranging from ±1.08 to 5.31, ±1.04 to 4.82 and ±0.28 to 3.09 and the relative standard deviation did not exceed ±6.23, ±2.77 and ±4.38% for A1, A2 and A3 complexes, respectively.

  11. CUMULATE ROCKS ASSOCIATED WITH CARBONATE ASSIMILATION, HORTAVÆR COMPLEX, NORTH-CENTRAL NORWAY

    Science.gov (United States)

    Barnes, C. G.; Prestvik, T.; Li, Y.

    2009-12-01

    The Hortavær igneous complex intruded high-grade metamorphic rocks of the Caledonian Helgeland Nappe Complex at ca. 466 Ma. The complex is an unusual mafic-silicic layered intrusion (MASLI) because the principal felsic rock type is syenite and because the syenite formed in situ rather than by deep-seated partial melting of crustal rocks. Magma differentiation in the complex was by assimilation, primarily of calc-silicate rocks and melts with contributions from marble and semi-pelites, plus fractional crystallization. The effect of assimilation of calcite-rich rocks was to enhance stability of fassaitic clinopyroxene at the expense of olivine, which resulted in alkali-rich residual melts and lowering of silica activity. This combination of MASLI-style emplacement and carbonate assimilation produced three types of cumulate rocks: (1) Syenitic cumulates formed by liquid-crystal separation. As sheets of mafic magma were loaded on crystal-rich syenitic magma, residual liquid was expelled, penetrating the overlying mafic sheets in flame structures, and leaving a cumulate syenite. (2) Reaction cumulates. Carbonate assimilation, illustrated by a simple assimilation reaction: olivine + calcite + melt = clinopyroxene + CO2 resulted in cpx-rich cumulates such as clinopyroxenite, gabbro, and mela-monzodiorite, many of which contain igneous calcite. (3) Magmatic skarns. Calc-silicate host rocks underwent partial melting during assimilation, yielding a Ca-rich melt as the principal assimilated material and permitting extensive reaction with surrounding magma to form Kspar + cpx + garnet-rich ‘cumulate’ rocks. Cumulate types (2) and (3) do not reflect traditional views of cumulate rocks but instead result from a series of melt-present discontinuous (peritectic) reactions and partial melting of calc-silicate xenoliths. In the Hortavær complex, such cumulates are evident because of the distinctive peritectic cumulate assemblages. It is unclear whether assimilation of

  12. Synthesis and reactivity towards diiodine of palladium(II) and platinum(II) complexes with non-cyclic and cyclic ligands (C6H3{CH=NR1R2}2-2,6)-. End-on diiodine-platinum(II) bonding in macrocyclic [PtI(C6H3{CH2NMe(CH2)7MeNCH2}-2,6)(h1-I2)

    NARCIS (Netherlands)

    Koten, G. van; Beek, J.A.M. van; Dekker, G.P.C.M.; Wissing, E.; Zoutberg, M.C.; Stam, C.H.

    1990-01-01

    Several new organo-platinum(II) and -palladium(II) complexes [MX(C{6}H{3}{CH{2}NR}1{R}2{}{2}-2, 6)] (X = halide, M = Pt, Pd; R}1{ = R}2{ = Et; R}2{ = Me, R}1{ = }t{Bu, M = Pt: R}2{ = Me, R}1{ = Ph) have been synthesized from [PtCl{2}(SEt{2}){2}] or [PdCl{2}(COD)] (COD = 1, 5-cyclooctadiene) by

  13. Carbon monoxide migratory insertion - A comparison of cationic and neutral palladium(II) complexes

    International Nuclear Information System (INIS)

    Frankcombe, K.; Cavell, K.J.; Yates, B.F.; Knott, R.B.

    1998-01-01

    With the use of ANSTO's resources and expertise and with support from AINSE, we have carried out extensive computer modelling on the mechanism of the palladium catalysed carbonylation reaction, a process which is used industrially in the conversion of carbon monoxide into biodegradable polymers. In this project, experimental and theoretical work has focussed on using Pd(II) complexes containing pyridine carboxylate ligands (NC 5 H 4 COO ) to explore the fundamental mechanistic steps. The results for subsequent steps in the catalytic cycle are presented and their implication for the design of more efficient catalysts are discussed

  14. Novel encapsulation method for probiotics using an interpolymer complex in supercriticial carbon dioxide

    CSIR Research Space (South Africa)

    Moolman, FS

    2006-10-01

    Full Text Available on Bioencapsulation, Lausanne, CH. Oct.6-7, 2006 O5-3 – page 1 A novel encapsulation method for probiotics using an interpolymer complex in supercriticial carbon dioxide F.S Moolman1, P.W. Labuschagne1, M.S. Thantsha2, T.L. van der Merwe1, H. Rolfes2 and T....cloete@up.ac.za 1. Introduction Evidence for the health benefits of probiotics is increasing. These benefits include protection against pathogenic bacteria, stimulation of the immune system, reduction in carcinogenesis, vitamin production and degradation...

  15. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    International Nuclear Information System (INIS)

    Mazurek, M.A.; Hildemann, L.M.; Simoneit, B.R.T.

    1990-10-01

    Organic aerosols comprise approximately 30% by mass of the total fine particulate matter present in urban atmospheres. The chemical composition of such aerosols is complex and reflects input from multiple sources of primary emissions to the atmosphere, as well as from secondary production of carbonaceous aerosol species via photochemical reactions. To identify discrete sources of fine carbonaceous particles in urban atmospheres, analytical methods must reconcile both bulk chemical and molecular properties of the total carbonaceous aerosol fraction. This paper presents an overview of the analytical protocol developed and used in a study of the major sources of fine carbon particles emitted to an urban atmosphere. 23 refs., 1 fig., 2 tabs

  16. Decomposition of uranyl peroxo-carbonato complex ion in the presence of metal oxides in carbonate media

    International Nuclear Information System (INIS)

    Dong-Yong Chung; Min-Sung Park; Keun-Young Lee; Eil-Hee Lee; Kwang-Wook Kim; Jei-Kwon Moon

    2015-01-01

    Uranium oxide was dissolved in the form of the uranyl peroxo-carbonato complex ion, UO 2 (O 2 )(CO 3 ) 2 4- in carbonate solutions with hydrogen peroxide. When UO 2 (O 2 )(CO 3 ) 2 4- ions lose their peroxide component, they become a stable species of uranyl tricarbonato complex ion, UO 2 (O 2 )(CO 3 ) 2 4- . The uranyl peroxo-carbonato complex self-decomposed more rapidly into the uranyl tricarbonato complex ion in the presence of a metal oxide in the carbonate solution. In this study, decomposition of the uranyl peroxo-carbonato complex in a carbonate solution was investigated in the presence of several metal oxides using absorption spectroscopy. (author)

  17. Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater

    International Nuclear Information System (INIS)

    Singha, Somdutta; Sarkar, Ujjaini; Luharuka, Pallavi

    2013-01-01

    Cr(VI) is present in the aqueous medium as chromate (CrO 4 2− ) and bi-chromate (HCrO 4 − ). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO 3 , HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5 m 2 /g), FAC-HNO 3 (648.8 m 2 /g) and FAC-HF (726.2 m 2 /g) are comparable to the GAC (777.7 m 2 /g). But, the adsorption capacity of each of the FAC-HNO 3 , FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO 4 2− and HCrO 4 − present. Surface complex formation is maximized in the order FAC-HNO 3 > FAC-HF > FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R 2 as high as 98.1% for FAC-HNO 3 . This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect. - Highlights: ► Physico-chemical adsorption using functionalized activated carbon (FACs) is applied. ► FACs

  18. Complexation/encapsulation of green tea polyphenols in mixed calcium carbonate and phosphate micro-particles.

    Science.gov (United States)

    Elabbadi, Amal; Jeckelmann, Nicolas; Haefliger, Olivier P; Ouali, Lahoussine

    2011-01-01

    We used a double-jet mixer to encapsulate water-soluble polyphenols, green tea extract (GTE), with calcium-based inorganic materials. The device mixed calcium chloride solutions with a solution of carbonate and phosphate in the presence of a GTE solution, and formed micro-particles which capture the GTE molecules. The micro-particles were analysed by liquid chromatography coupled to tandem mass spectroscopy to determine the encapsulation yield and loading of the different GTE components. We established correlations between (1) the efficiency of the GTE encapsulation and the composition of the mixed anion solutions and (2) the protonation degree of the ions and the molar ratio of calcium cations and carbonate/phosphate anions. An optimal and reproducible GTE loading of about 40% with an encapsulation yield of 65% was observed for a carbonate/phosphate molar composition of 4 : 1. In addition, our experimental results showed that the process is selective and favours the encapsulation of gallated species which form stronger complexes with calcium cations.

  19. Complex resistivity spectra in relation to multiscale pore geometry in carbonates and mixed-siliciclastic rocks

    Science.gov (United States)

    Norbisrath, Jan Henrik

    Carbonate rocks are known to have complex and heterogeneous pore structures, which result from their biogenic origin and strong affinity for diagenetic processes that change their pore structure after burial. The combination of sheer endless variations of precursor biogenic material, depositional environments, and diagenetic effects results in rocks that are interesting to study but intricate to understand. Many schemes to categorize the diversity of carbonate rocks are in use today; most are based on the macropore structure and qualitative thin-section analysis. Many studies, however, acknowledge that micropores have a significant influence on the macroscopic petrophysical rock properties, which are essential to determine reservoir quality. Micropores are, by definition, smaller than the thickness of a thin-section (four major carbonate microporosity types: (1) small intercrystalline, (2) large inter-crystalline, (3) intercement, and (4) micromoldic. Each microporosity type shows a distinct capacity to conduct electrical charge, which largely controls the magnitude and range of cementation factors (m) in rocks with such microporosity type. The BIB-SEM method is also used on a dataset of mixed carbonate-siliciclastic (mudrock) samples with high kerogen and pyrite content. Results show that the nanopore geometry here has little influence on cementation factors, and instead porosity is the main control on m in mudrocks. Cementation factors are crucial for estimates of oil-in-place and water saturation in a wireline application, and a slight change of (assumed) cementation factor can change the interpreter's evaluation from dry hole to discovery. Therefore, accurate determination of cementation factors is a critical task in formation evaluation, similar to accurate estimates of permeability. To achieve this goal, this dissertation utilizes a new approach of using complex resistivity spectra (CRS) to assess the pore geometry and its resulting electrical and fluid flow

  20. Flow and Transport in Complex Microporous Carbonates as a Consequence of Separation of Scales

    Science.gov (United States)

    Bijeljic, B.; Raeini, A. Q.; Lin, Q.; Blunt, M. J.

    2017-12-01

    Some of the most important examples of flow and transport in complex pore structures are found in subsurface applications such as contaminant hydrology, carbon storage and enhanced oil recovery. Carbonate rock structures contain most of the world's oil reserves, considerable amount of water reserves, and potentially hold a storage capacity for carbon dioxide. However, this type of pore space is difficult to represent due to complexities associated with a wide range of pore sizes and variation in connectivity which poses a considerable challenge for quantitative predictions of transport across multiple scales.A new concept unifying X-ray tomography experiment and direct numerical simulation has been developed that relies on full description flow and solute transport at the pore scale. Differential imaging method (Lin et al. 2016) provides rich information in microporous space, while advective and diffusive mass transport are simulated on micro-CT images of pore-space: Navier-Stokes equations are solved for flow in the image voxels comprising the pore space, streamline-based simulation is used to account for advection, and diffusion is superimposed by random walk.Quantitative validation has been done on analytical solutions for diffusion and by comparing the model predictions versus the experimental NMR measurements in the dual porosity beadpack. Furthermore, we discriminate signatures of multi-scale transport behaviour for a range of carbonate rock (Figure 1), dependent on the heterogeneity of the inter- and intra-grain pore space, heterogeneity in the flow field, and the mass transfer characteristics of the porous media. Finally, we demonstrate the predictive capabilities of the model through an analysis that includes a number of probability density functions flow and transport (PDFs) measures of non-Fickian transport on the micro-CT i935mages. In complex porous media separation of scales exists, leading to flow and transport signatures that need to be described by

  1. Monolayer-by-monolayer growth of platinum films on complex carbon fiber paper structure

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Liuqing; Zhang, Yunxia [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); Liu, Shengzhong, E-mail: szliu@dicp.ac.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); Dalian National Laboratory for Clean Energy, iChEM, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2017-06-15

    Graphical abstract: A controlled monolayer-by-monolayer deposition process has been developed to fabricate Pt coating on carbon fiber paper with complex network structures using a dual buffer strategy. This development may pave a way to fabricate superior Pt catalysts with the minimal Pt usage. In fact, the present Pt group metal loading is 25 times lower than the U.S. DOE 2017 target value. - Highlights: • Developed a controlled monolayer-by-monolayer Pt deposition using a dual buffer strategy. • The present Pt group metal loading is 25 times lower than the U.S. DOE 2017 target value. • This development may pave a way to fabricate superior Pt catalysts with the minimal Pt usage. - Abstract: A controlled monolayer-by-monolayer deposition process has been developed to fabricate Pt coating on carbon fiber paper with complex network structures using a dual buffer (Au/Ni) strategy. The X-ray diffraction, electrochemical quartz crystal microbalance, current density analyses, and X-ray photoelectron spectroscopy results conclude that the monolayer deposition process accomplishes full coverage on the substrate and that the thickness of the deposition layer can be controlled on a single atom scale. This development may pave a way to fabricate superior Pt catalysts with the minimal Pt usage. In fact, the present Pt group metal loading is 25 times lower than the U.S. DOE 2017 target value.

  2. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, D.; Barbrel, B.; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Vorberger, J. [Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden (Germany); Helfrich, J.; Frydrych, S.; Ortner, A.; Otten, A.; Roth, F.; Schaumann, G.; Schumacher, D.; Siegenthaler, K.; Wagner, F.; Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt (Germany); Gericke, D. O.; Wünsch, K. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Bachmann, B.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Bagnoud, V.; Blažević, A. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); and others

    2015-05-15

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  3. Bacterial synergism in lignocellulose biomass degradation : Complementary roles of degraders as influenced by complexity of the carbon source

    NARCIS (Netherlands)

    Cortes Tolalpa, Larisa; Falcao Salles, Joana; van Elsas, Jan

    2017-01-01

    Lignocellulosic biomass (LCB) is an attractive source of carbon for the production of sugars and other chemicals. Due to its inherent complexity and heterogeneity, efficient biodegradation requires the actions of different types of hydrolytic enzymes. In nature, complex microbial communities that

  4. Temperature and ionic strength influences on actinide(VI)/(V) redox potentials for carbonate limiting complexes

    International Nuclear Information System (INIS)

    Capdevila, H.; Vitorge, P.

    1998-01-01

    Actinide behaviour was studied in two limiting aqueous solutions: acidic and carbonate. Cyclic voltametry was validated with well-known U redox system. SIT was used to account for I influence. Taylor's series expansions to the second order were used to account for T influence. Redox potentials of actinide couples had previously been measured in non complexing media. The above data treatments give standard values for redox potential E 0 , for the corresponding entropy ΔS 0 , enthalpy ΔH 0 and heat capacity ΔC p 0 changes, and also for the corresponding excess values (i.e. the variation of these thermodynamic constants with ionic strength). This methodology was here used in carbonate media to measure the potential of the redox couple PuO 2 (CO 3 ) 3 4- /PuO 2 (CO 3 ) 3 5- from 5 to 70 degC and from I = 0.5 to 4.5 M in Na 2 CO 3 , NaClO 4 media. Experimental details and full results are given for Pu. Only final results are given for Np. Previous and/or published data for U and Am are discussed. E and ΔS variations with T or I were enough to be measured. The values obtained for the fitted SIT coefficients Δε, and for ΔS and ΔCp are similar for U, Np and Pu redox reactions. Using this analogy for Am missing data is discussed. β 3 V /β 3 VI formation constant ratio of the carbonate limiting complexes were deduced from the potential shift from complexing to non complexing media for the Actinide(VI)/Actinide(V) redox couples. β 3 V (U and Pu) and β 3 VI (Np) were finally proposed using published β3 VI (U and Pu) and β 3 V (Np). For Am, this data treatment was used to discuss the AmO 2 2+ / AmO 2 + redox potential

  5. Carbene complexes of zirconium. Synthesis, structure, and reactivity with carbon monoxide to affort coordinated ketene

    International Nuclear Information System (INIS)

    Barger, P.T.; Santarsiero, B.D.; Armantrout, J.; Bercaw, J.E.

    1984-01-01

    Treatment of Cp 2 Zr(L)(CO) (Cp = C 5 H 5 ; L = PMe 3 , CO) with Cp* 2 ZrH 2 (Cp* = C 5 Me 5 ) affords zirconium oxycarbene complexes, Cp 2 (L)Zr double bond CHO single bond Zr(X)Cp* 2 (L = PMe 3 , X = H, I; L = CO, X = H), that represent some of the first examples of group 4 metal-to-carbon multiple bonding. The first X-ray diffraction structure determination of a zirconium carbene complex, that of Cp(PMe 3 )Zr double bond CHO single bond Zr(H)Cp* 2 .C 6 H 6 , is reported (C2/c, a = 27.318 (4) A, b = 19.895 (3) A, c = 19.932 (5) A β = 132.188 (10) 0 , Z = 8) and shows a very short Zr-C bond length of 2.117 (7) A. Treatment of Cp 2 (CO)Zr double bond CHO single bond Zr(H)Cp* 2 with CH 3 I or Cp 2 (PMe 3 )Zr double bond CHO single bond Zr(I)Cp* 2 with CO affords the zirconium substituted enediolate zirconacycle, Cp* 2 ZrOCH double bond C(Zr(I)Cp 2 )O, which has been characterized by an X-ray diffraction study (P2 1 /c, a = 15.866 (4) A, b = 10.673 (3) A, c = 20.561 (4) A, β = 105.5 (2) 0 , Z = 4). This complex most likely forms by coupling of the zirconoxycarbene and a carbonyl to give a metal-coordinated ketene intermediate that subsequently rearranges to the isolated product. An isotopic crossover experiment has demonstrated that the new carbon-carbon bond is formed in an intramolecular coupling step. The ketene intermediate can be trapped by dissolving Cp 2 (CO)Zr double bond CHO single bond Zr(H)Cp* 2 in pyridine, giving Cp 2 (py)Zr(O double bond C double bond CHOZr(I)Cp* 2 ). Treatment of the isolated ketene complex with CH 3 I in benzene gives the enediolate zirconocycle; in pyridine Cp 2 (py)Zr(O double bond C double bond CHOZr(I)Cp* 2 ) can be observed spectroscopically. 38 references, 4 figures, 5 tables

  6. Peptide aptamer-assisted immobilization of green fluorescent protein for creating biomolecule-complexed carbon nanotube device

    Science.gov (United States)

    Nii, Daisuke; Nozawa, Yosuke; Miyachi, Mariko; Yamanoi, Yoshinori; Nishihara, Hiroshi; Tomo, Tatsuya; Shimada, Yuichiro

    2017-10-01

    Carbon nanotubes are a novel material for next-generation applications. In this study, we generated carbon nanotube and green fluorescent protein (GFP) conjugates using affinity binding peptides. The carbon nanotube-binding motif was introduced into the N-terminus of the GFP through molecular biology methods. Multiple GFPs were successfully aligned on a single-walled carbon nanotube via the molecular recognition function of the peptide aptamer, which was confirmed through transmission electron microscopy and optical analysis. Fluorescence spectral analysis results also suggested that the carbon nanotube-GFP complex was autonomously formed with orientation and without causing protein denaturation during immobilization. This simple process has a widespread potential for fabricating carbon nanotube-biomolecule hybrid devices.

  7. Theoretical study of the binding nature of glassy carbon with nickel(II) phthalocyanine complexes

    International Nuclear Information System (INIS)

    Cortez, Luis; Berrios, Cristhian; Yanez, Mauricio; Cardenas-Jiron, Gloria I.

    2009-01-01

    A theoretical study at the semiempirical RHF/PM3(tm) level (tm: transition metal) of the binding nature between a glassy carbon (GC) cluster and a nickel(II) complex (nickel(II) phthalocyanine NiPc, nickel(II) tetrasulphophthalocyanine NiTSPc) was performed. Three types of interactions for GC...NiPc (NiTSPc) were studied: (a) through an oxo (O) bridge, (b) through an hydroxo (OH) bridge, and (c) non-bridge. One layer (NiPc, NiTSPc) and two layers (NiPc...NiPc) of complex were considered. The binding energy calculated showed that in both cases NiPc and NiTSPc, the oxo structures are more stable than the hydroxo ones, and than the non-bridge systems. Charge analysis (NAO) predicted that GC gained more electrons in an oxo structure than in the analogues hydroxo. The theoretical results showed an agreement with the experimental data available, an oxo binding between GC and a nickel complex (NiPc, NiTSPc) in aqueous alkaline solutions is formed.

  8. Theoretical study of the binding nature of glassy carbon with nickel(II) phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Cortez, Luis [Laboratorio de Quimica Teorica, Facultad de Quimica y Biologia, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago (Chile); Berrios, Cristhian [Laboratorio de Electrocatalisis, Facultad de Quimica y Biologia, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago (Chile); Yanez, Mauricio [Laboratorio de Recursos Renovables, Centro de Biotecnologia, Universidad de Concepcion, Casilla-160 C, Concepcion (Chile); Cardenas-Jiron, Gloria I., E-mail: gloria.cardenas@usach.cl [Laboratorio de Quimica Teorica, Facultad de Quimica y Biologia, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago (Chile)

    2009-11-26

    A theoretical study at the semiempirical RHF/PM3(tm) level (tm: transition metal) of the binding nature between a glassy carbon (GC) cluster and a nickel(II) complex (nickel(II) phthalocyanine NiPc, nickel(II) tetrasulphophthalocyanine NiTSPc) was performed. Three types of interactions for GC...NiPc (NiTSPc) were studied: (a) through an oxo (O) bridge, (b) through an hydroxo (OH) bridge, and (c) non-bridge. One layer (NiPc, NiTSPc) and two layers (NiPc...NiPc) of complex were considered. The binding energy calculated showed that in both cases NiPc and NiTSPc, the oxo structures are more stable than the hydroxo ones, and than the non-bridge systems. Charge analysis (NAO) predicted that GC gained more electrons in an oxo structure than in the analogues hydroxo. The theoretical results showed an agreement with the experimental data available, an oxo binding between GC and a nickel complex (NiPc, NiTSPc) in aqueous alkaline solutions is formed.

  9. Architecture and evolution of an Early Permian carbonate complex on a tectonically active island in east-central California

    Science.gov (United States)

    Stevens, Calvin H.; Magginetti, Robert T.; Stone, Paul

    2015-01-01

    The newly named Upland Valley Limestone represents a carbonate complex that developed on and adjacent to a tectonically active island in east-central California during a brief interval of Early Permian (late Artinskian) time. This lithologically unique, relatively thin limestone unit lies within a thick sequence of predominantly siliciclastic rocks and is characterized by its high concentration of crinoidal debris, pronounced lateral changes in thickness and lithofacies, and a largely endemic fusulinid fauna. Most outcrops represent a carbonate platform and debris derived from it and shed downslope, but another group of outcrops represents one or possibly more isolated carbonate buildups that developed offshore from the platform. Tectonic activity in the area occurred before, probably during, and after deposition of this short-lived carbonate complex.

  10. Thermal decomposition and Moessbauer analysis of two iron hydroxy-carbonate complexes

    International Nuclear Information System (INIS)

    Greaves, T.L.; Cashio, J.D.; Turney, T.

    2002-01-01

    Full text:The two iron hydroxy carbonate complexes (NH 4 ) 2 Fe 2 (OH) 4 (CO 3 ) 2 .H 2 O and (NH 4 ) 4 Fe 2 (OH) 4 (CO 3 ) 3 .3H 2 O were prepared by the method of Dvo a k and Feitknecht. Moessbauer spectra of the first sample at room temperature and 81K showed principally a ferric doublet with a small quadrupole splitting while spectra of the second sample showed a broad ferric doublet with a large mean quadrupole splitting of 1mm/s. Parameters for both spectra were characteristic of distorted octahedral coordination to oxygens. Thermal gravimetric analysis of both samples up to 750 K showed several fractions corresponding to the loss of the more volatile components

  11. Clean exergy biotechnical complex for recycling carbon dioxide from flue gas stations

    Energy Technology Data Exchange (ETDEWEB)

    Stolyarenko, G. [Cherkassy State Technological University, Cherkassy (Ukraine)

    2013-07-01

    A main problem, impedimental to the use of smoke gases as raw material for the production of pure carbon dioxide, is formation at incineration of fuel of such toxic connections as oxide of carbon(II), nitrogen oxides, and benzo (a) pyrene, formaldehyde, vapors of hydrochloric and hydrofluoric acids, toxic metals. Suppressions of formation CO, NO{sub x} and other harmful admixtures in smoke gases it is possible to attain on the stage of burning with the use of new technology: electronic catalysis of flame in the discharge zone. Method of heterophasic ozonization minimizes content CO and NO{sub x} and other toxic admixtures in smoke gases. Photosynthesis - by converting pure CO{sub 2} into hydrocarbons with the use of solar energy - enables to receive on a commercial scale genetically modified cyano-bacteria (blue-green algae). Oils got from them, a gaseous and diesel fuel during incineration results in the decline of maintenance of toxic connections in smoke gases. Thus achieves the creation of clean energy bio-complex. (author)

  12. Clean exergy biotechnical complex for recycling carbon dioxide from flue gas stations

    International Nuclear Information System (INIS)

    Stolyarenko, G.

    2013-01-01

    A main problem, impedimental to the use of smoke gases as raw material for the production of pure carbon dioxide, is formation at incineration of fuel of such toxic connections as oxide of carbon(II), nitrogen oxides, and benzo (a) pyrene, formaldehyde, vapors of hydrochloric and hydrofluoric acids, toxic metals. Suppressions of formation CO, NO x and other harmful admixtures in smoke gases it is possible to attain on the stage of burning with the use of new technology: electronic catalysis of flame in the discharge zone. Method of heterophasic ozonization minimizes content CO and NO x and other toxic admixtures in smoke gases. Photosynthesis - by converting pure CO 2 into hydrocarbons with the use of solar energy - enables to receive on a commercial scale genetically modified cyano-bacteria (blue-green algae). Oils got from them, a gaseous and diesel fuel during incineration results in the decline of maintenance of toxic connections in smoke gases. Thus achieves the creation of clean energy bio-complex. (author)

  13. Surface Complexation Modeling of Calcite Zeta Potential Measurement in Mixed Brines for Carbonate Wettability Characterization

    Science.gov (United States)

    Song, J.; Zeng, Y.; Biswal, S. L.; Hirasaki, G. J.

    2017-12-01

    We presents zeta potential measurements and surface complexation modeling (SCM) of synthetic calcite in various conditions. The systematic zeta potential measurement and the proposed SCM provide insight into the role of four potential determining cations (Mg2+, SO42- , Ca2+ and CO32-) and CO2 partial pressure in calcite surface charge formation and facilitate the revealing of calcite wettability alteration induced by brines with designed ionic composition ("smart water"). Brines with varying potential determining ions (PDI) concentration in two different CO2 partial pressure (PCO2) are investigated in experiments. Then, a double layer SCM is developed to model the zeta potential measurements. Moreover, we propose a definition for contribution of charged surface species and quantitatively analyze the variation of charged species contribution when changing brine composition. After showing our model can accurately predict calcite zeta potential in brines containing mixed PDIs, we apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential applications in carbonate enhanced oil recovery including miscible CO2 flooding and CO2 sequestration in carbonate reservoirs. Model prediction reveals that pure calcite surface will be positively charged in all investigated brines in pressurized CO2 environment (>1atm). Moreover, the sensitivity of calcite zeta potential to CO2 partial pressure in the various brine is found to be in the sequence of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength=0.1M).

  14. Carbon-tuned bonding method significantly enhanced the hydrogen storage of BN-Li complexes.

    Science.gov (United States)

    Deng, Qing-ming; Zhao, Lina; Luo, You-hua; Zhang, Meng; Zhao, Li-xia; Zhao, Yuliang

    2011-11-01

    Through first-principles calculations, we found doping carbon atoms onto BN monolayers (BNC) could significantly strengthen the Li bond on this material. Unlike the weak bond strength between Li atoms and the pristine BN layer, it is observed that Li atoms are strongly hybridized and donate their electrons to the doped substrate, which is responsible for the enhanced binding energy. Li adsorbed on the BNC layer can serve as a high-capacity hydrogen storage medium, without forming clusters, which can be recycled at room temperature. Eight polarized H(2) molecules are attached to two Li atoms with an optimal binding energy of 0.16-0.28 eV/H(2), which results from the electrostatic interaction of the polarized charge of hydrogen molecules with the electric field induced by positive Li atoms. This practical carbon-tuned BN-Li complex can work as a very high-capacity hydrogen storage medium with a gravimetric density of hydrogen of 12.2 wt%, which is much higher than the gravimetric goal of 5.5 wt % hydrogen set by the U.S. Department of Energy for 2015.

  15. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    Science.gov (United States)

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; Vuitton, V.; Crary, F. J.; González-Caniulef, D.; Shebanits, O.; Jones, G. H.; Lewis, G. R.; Waite, J. H.; Cordiner, M.; Taylor, S. A.; Kataria, D. O.; Wahlund, J.-E.; Edberg, N. J. T.; Sittler, E. C.

    2017-08-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q-1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950-1300 km. We report on detections consistently centered between 25.8 and 26.0 u q-1 and between 49.0-50.1 u q-1 which are identified as belonging to the carbon chain anions, CN-/C3N- and/or C2H-/C4H-, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73-74 u q-1 could be attributed to the further carbon chain anions C5N-/C6H- but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  16. Highly efficient one-step synthesis of carbon encapsulated nanocrystals by the oxidation of metal π-complexes

    Science.gov (United States)

    Liu, Boyang; Shao, Yingfeng; Xiang, Xin; Zhang, Fuhua; Yan, Shengchang; Li, Wenge

    2017-08-01

    Various carbon encapsulated nanocrystals, including MnS and MnO, Cr2O3, MoO2, Fe7S8 and Fe3O4, and ZrO2, are prepared in one step and in situ by a simple and highly efficient synthesis approach. The nanocrystals have an equiaxed morphology and a median size smaller than 30 nm. Tens and hundreds of these nanocrystals are entirely encapsulated by a wormlike amorphous carbon shell. The formation of a core-shell structure depends on the strongly exothermic reaction of metal π-complexes with ammonium persulfate in an autoclave at below 200 °C. During the oxidation process, the generated significant amounts of heat will destroy the molecular structure of the metal π-complex and cleave the ligands into small carbon fragments, which further transform into an amorphous carbon shell. The central metal atoms are oxidized to metal oxide/sulfide nanocrystals. The formation of a core-shell structure is independent of the numbers of ligands and carbon atoms as well as the metal types, implying that any metal π-complex can serve as a precursor and that various carbon encapsulated nanocrystals can be synthesized by this method.

  17. Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Singha, Somdutta; Sarkar, Ujjaini, E-mail: usarkar@chemical.jdvu.ac.in; Luharuka, Pallavi

    2013-03-01

    Cr(VI) is present in the aqueous medium as chromate (CrO{sub 4}{sup 2−}) and bi-chromate (HCrO{sub 4}{sup −}). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO{sub 3}, HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5 m{sup 2}/g), FAC-HNO{sub 3} (648.8 m{sup 2}/g) and FAC-HF (726.2 m{sup 2}/g) are comparable to the GAC (777.7 m{sup 2}/g). But, the adsorption capacity of each of the FAC-HNO{sub 3}, FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO{sub 4}{sup 2−} and HCrO{sub 4}{sup −} present. Surface complex formation is maximized in the order FAC-HNO{sub 3} > FAC-HF > FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R{sup 2} as high as 98.1% for FAC-HNO{sub 3}. This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect. - Highlights: ► Physico

  18. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

    Science.gov (United States)

    Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

    2012-09-30

    This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures

    International Nuclear Information System (INIS)

    Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

    2012-01-01

    Highlights: ► The stability of peroxide in uranyl peroxo carbonato complex solutions with different temperatures was characterized. ► The decomposition rate of uranyl peroxo carbonato complex ion to uranyl tris-carbonato complex ion was observed to increase with temperature ► The decomposition kinetics of uranyl peroxo carbonato complex ions was evaluated by absorption and Raman spectroscopies. ► A precipitate of uranyl peroxo carbonato complex solution was evaluated with XRD. - Abstract: This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144 × 10 3 J mol −1 . The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature.

  20. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang-Wook, E-mail: nkwkim@kaeri.re.kr [Korea Atomic Energy Research Institute, 1045 Daedeok daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon [Korea Atomic Energy Research Institute, 1045 Daedeok daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Shin, Dong-Woo [Gyeongsang National University, 900 Gajwa, Jinju 660-701 (Korea, Republic of)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer The stability of peroxide in uranyl peroxo carbonato complex solutions with different temperatures was characterized. Black-Right-Pointing-Pointer The decomposition rate of uranyl peroxo carbonato complex ion to uranyl tris-carbonato complex ion was observed to increase with temperature Black-Right-Pointing-Pointer The decomposition kinetics of uranyl peroxo carbonato complex ions was evaluated by absorption and Raman spectroscopies. Black-Right-Pointing-Pointer A precipitate of uranyl peroxo carbonato complex solution was evaluated with XRD. - Abstract: This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144 Multiplication-Sign 10{sup 3} J mol{sup -1}. The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature.

  1. Platinum(II) complexes with steroidal esters of L-methionine and L-histidine: Synthesis, characterization and cytotoxic activity

    Czech Academy of Sciences Publication Activity Database

    Kvasnica, Miroslav; Buděšínský, Miloš; Swaczynová, Jana; Pouzar, Vladimír; Kohout, Ladislav

    2008-01-01

    Roč. 16, č. 7 (2008), s. 3704-3713 ISSN 0968-0896 R&D Projects: GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50380511 Keywords : steroids * platinum * L-histidin * L-methionin Subject RIV: CC - Organic Chemistry Impact factor: 3.075, year: 2008

  2. Conformation and recognition of DNA damaged by antitumor cis-dichlorido platinum(II) complex of CDK inhibitor bohemine

    Czech Academy of Sciences Publication Activity Database

    Nováková, Olga; Lišková, Barbora; Vystrčilová, Jana; Suchánková, Tereza; Vrána, Oldřich; Starha, P.; Trávníček, Z.; Brabec, Viktor

    2014-01-01

    Roč. 78, MAY2014 (2014), s. 54-64 ISSN 0223-5234 R&D Projects: GA ČR(CZ) GA13-08273S Institutional support: RVO:68081707 Keywords : Antitumor * Platinum * DNA Subject RIV: BO - Biophysics Impact factor: 3.447, year: 2014

  3. Analysis of the transmission characteristics of China's carbon market transaction price volatility from the perspective of a complex network.

    Science.gov (United States)

    Jia, Jingjing; Li, Huajiao; Zhou, Jinsheng; Jiang, Meihui; Dong, Di

    2018-03-01

    Research on the price fluctuation transmission of the carbon trading pilot market is of great significance for the establishment of China's unified carbon market and its development in the future. In this paper, the carbon market transaction prices of Beijing, Shanghai, Tianjin, Shenzhen, and Guangdong were selected from December 29, 2013 to March 26, 2016, as sample data. Based on the view of the complex network theory, we construct a price fluctuation transmission network model of five pilot carbon markets in China, with the purposes of analyzing the topological features of this network, including point intensity, weighted clustering coefficient, betweenness centrality, and community structure, and elucidating the characteristics and transmission mechanism of price fluctuation in China's five pilot cities. The results of point intensity and weighted clustering coefficient show that the carbon prices in the five markets remained unchanged and transmitted smoothly in general, and price fragmentation is serious; however, at some point, the price fluctuates with mass phenomena. The result of betweenness centrality reflects that a small number of price fluctuations can control the whole market carbon price transmission and price fluctuation evolves in an alternate manner. The study provides direction for the scientific management of the carbon price. Policy makers should take a positive role in promoting market activity, preventing the risks that may arise from mass trade and scientifically forecasting the volatility of trading prices, which will provide experience for the establishment of a unified carbon market in China.

  4. Degraded tropical rain forests possess valuable carbon storage opportunities in a complex, forested landscape.

    Science.gov (United States)

    Alamgir, Mohammed; Campbell, Mason J; Turton, Stephen M; Pert, Petina L; Edwards, Will; Laurance, William F

    2016-07-20

    Tropical forests are major contributors to the terrestrial global carbon pool, but this pool is being reduced via deforestation and forest degradation. Relatively few studies have assessed carbon storage in degraded tropical forests. We sampled 37,000 m(2) of intact rainforest, degraded rainforest and sclerophyll forest across the greater Wet Tropics bioregion of northeast Australia. We compared aboveground biomass and carbon storage of the three forest types, and the effects of forest structural attributes and environmental factors that influence carbon storage. Some degraded forests were found to store much less aboveground carbon than intact rainforests, whereas others sites had similar carbon storage to primary forest. Sclerophyll forests had lower carbon storage, comparable to the most heavily degraded rainforests. Our findings indicate that under certain situations, degraded forest may store as much carbon as intact rainforests. Strategic rehabilitation of degraded forests could enhance regional carbon storage and have positive benefits for tropical biodiversity.

  5. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    Energy Technology Data Exchange (ETDEWEB)

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; González-Caniulef, D.; Jones, G. H.; Lewis, G. R.; Taylor, S. A.; Kataria, D. O. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Surrey RH5 6NT (United Kingdom); Vuitton, V. [Université Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble (France); Crary, F. J. [Laboratory for Atmospheric and Space Physics, University of Colorado, Innovation Drive, Boulder, CO 80303 (United States); Shebanits, O.; Wahlund, J.-E. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Waite, J. H. [Space Science and Engineering Division, Southwest Research Institute (SWRI), 6220 Culebra Road, San Antonio, TX 78238 (United States); Cordiner, M.; Sittler, E. C. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Edberg, N. J. T., E-mail: r.t.desai@ucl.ac.uk [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)

    2017-08-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q{sup −1}. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950–1300 km. We report on detections consistently centered between 25.8 and 26.0 u q{sup −1} and between 49.0–50.1 u q{sup −1} which are identified as belonging to the carbon chain anions, CN{sup −}/C{sub 3}N{sup −} and/or C{sub 2}H{sup −}/C{sub 4}H{sup −}, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73–74 u q{sup −1} could be attributed to the further carbon chain anions C{sub 5}N{sup −}/C{sub 6}H{sup −} but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q{sup −1}) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  6. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    International Nuclear Information System (INIS)

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; González-Caniulef, D.; Jones, G. H.; Lewis, G. R.; Taylor, S. A.; Kataria, D. O.; Vuitton, V.; Crary, F. J.; Shebanits, O.; Wahlund, J.-E.; Waite, J. H.; Cordiner, M.; Sittler, E. C.; Edberg, N. J. T.

    2017-01-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q"−"1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950–1300 km. We report on detections consistently centered between 25.8 and 26.0 u q"−"1 and between 49.0–50.1 u q"−"1 which are identified as belonging to the carbon chain anions, CN"−/C_3N"− and/or C_2H"−/C_4H"−, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73–74 u q"−"1 could be attributed to the further carbon chain anions C_5N"−/C_6H"− but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q"−"1) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  7. Evolution of multi-mineral formation evaluation using LWD data in complex carbonates offshore Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, Paolo; Borovskaya, Irina [Schlumberger, Houston, TX (United States)

    2012-07-01

    Petrophysical Formation Evaluation using Logging While Drilling (LWD) measurements is a new requisite when drilling in carbonates reservoirs offshore Brazil. These reservoirs are difficult to characterize due to an unusual mixture of the minerals constituting the matrix and affecting rock texture. As wells are getting deeper and more expensive, an early identification of the drilled targets potential is necessary for valuable decisions. Brazil operators have been especially demanding towards service providers, pushing for development of suitable services able to positively identify and quantify not only the presence of hydrocarbons but also their flowing capability. In addition to the standard gamma ray / resistivity / porosity and density measurements, three new measurements have proven to be critical to evaluate complex carbonate formations: Nuclear Magnetic Resonance (NMR), Spectroscopy and Capture Cross-Section (sigma). Under appropriate logging conditions, NMR data provides lithology independent porosity, bound and free fluids fractions, reservoir texture and permeability. Capture Spectroscopy allows assessment of mineral composition in terms of calcite, dolomite, quartz and clay fractions, and in addition highlights presence of other heavier minerals. Finally, sigma allows performing a volumetric formation evaluation without requiring custom optimization of the classical exponents used in all forms of resistivity saturation equations. All these new measurements are inherently statistical and if provided by wireline after drilling the well they may result in significant usage of rig time. When acquired simultaneously while drilling they have three very clear advantages: 1) no extra rig time, 2) improved statistics due to long formation exposure (drilling these carbonates is a slow process and rate of penetration (ROP) rarely exceeds 10 m/hr), 3) less invasion effect and better hole condition. This paper describes the development of two LWD tools performing the

  8. Formation and annealing of metastable (interstitial oxygen)-(interstitial carbon) complexes in n- and p-type silicon

    CERN Document Server

    Makarenko, L F; Lastovskii, S B; Murin, L I; Moll, M; Pintilie, I

    2014-01-01

    It is shown experimentally that, in contrast to the stable configuration of (interstitial carbon)-(interstitial oxygen) complexes (CiOi), the corresponding metastable configuration (CiOi{*}) cannot be found in n-Si based structures by the method of capacitance spectroscopy. The rates of transformation CiOi{*} -> CiOi are practically the same for both n- and p-Si with a concentration of charge carriers of no higher than 10(13) cm(-3). It is established that the probabilities of the simultaneous formation of stable and metastable configurations of the complex under study in the case of the addition of an atom of interstitial carbon to an atom of interstitial oxygen is close to 50\\%. This is caused by the orientation dependence of the interaction potential of an atom of interstitial oxygen with an interstitial carbon atom, which diffuses to this oxygen atom.

  9. Iridium and ruthenium complexes covalently bonded to carbon surfaces by means of electrochemical oxidation of aromatic amines

    Czech Academy of Sciences Publication Activity Database

    Sandroni, M.; Volpi, G.; Fiedler, Jan; Buscaino, R.; Viscardi, G.; Milone, L.; Gobetto, R.; Nervi, C.

    2010-01-01

    Roč. 158, 1-2 (2010), s. 22-28 ISSN 0920-5861 R&D Projects: GA ČR GA203/09/0705 Institutional research plan: CEZ:AV0Z40400503 Keywords : functionalization * glassy carbon electrode * metallorganic complexes * cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 2.993, year: 2010

  10. Simplifying the complexity of a coupled carbon turnover and pesticide degradation model

    Science.gov (United States)

    Marschmann, Gianna; Erhardt, André H.; Pagel, Holger; Kügler, Philipp; Streck, Thilo

    2016-04-01

    The mechanistic one-dimensional model PECCAD (PEsticide degradation Coupled to CArbon turnover in the Detritusphere; Pagel et al. 2014, Biogeochemistry 117, 185-204) has been developed as a tool to elucidate regulation mechanisms of pesticide degradation in soil. A feature of this model is that it integrates functional traits of microorganisms, identifiable by molecular tools, and physicochemical processes such as transport and sorption that control substrate availability. Predicting the behavior of microbially active interfaces demands a fundamental understanding of factors controlling their dynamics. Concepts from dynamical systems theory allow us to study general properties of the model such as its qualitative behavior, intrinsic timescales and dynamic stability: Using a Latin hypercube method we sampled the parameter space for physically realistic steady states of the PECCAD ODE system and set up a numerical continuation and bifurcation problem with the open-source toolbox MatCont in order to obtain a complete classification of the dynamical system's behaviour. Bifurcation analysis reveals an equilibrium state of the system entirely controlled by fungal kinetic parameters. The equilibrium is generally unstable in response to small perturbations except for a small band in parameter space where the pesticide pool is stable. Time scale separation is a phenomenon that occurs in almost every complex open physical system. Motivated by the notion of "initial-stage" and "late-stage" decomposers and the concept of r-, K- or L-selected microbial life strategies, we test the applicability of geometric singular perturbation theory to identify fast and slow time scales of PECCAD. Revealing a generic fast-slow structure would greatly simplify the analysis of complex models of organic matter turnover by reducing the number of unknowns and parameters and providing a systematic mathematical framework for studying their properties.

  11. Organomineral Complexation at the Nanoscale: Iron Speciation and Soil Carbon Stabilization

    Science.gov (United States)

    Coward, E.; Thompson, A.; Plante, A. F.

    2016-12-01

    Much of the uncertainty in the biogeochemical behavior of soil carbon (C) in tropical ecosystems derives from an incomplete understanding of soil C stabilization processes. The 2:1 phyllosilicate clays often associated with temperate organomineral complexation are largely absent in tropical soils due to extensive weathering. In contrast, these soils contain an abundance of Fe- and Al-containing short-range-order (SRO) mineral phases capable of C stabilization through sorption or co-precipitation, largely enabled by high specific surface area (SSA). SRO-mediated organomineral associations may thus prove a critical, yet matrix-selective, driver of the long-term C stabilization capacity observed in tropical soils. Characterizing the interactions between inherently heterogeneous organic matter and amorphous mineralogy presses the limits of current analytical techniques. This work pairs inorganic selective dissolution with high-resolution assessment of Fe speciation to determine the contribution of extracted mineral phases to the mineral matrix, and to C stabilization capacity. Surface (0-20 cm) samples were taken from 20 quantitative soil pits within the Luquillo Critical Zone Observatory in northeast Puerto Rico stratified across granodioritic and volcaniclastic parent materials. 57Fe-Mössbauer spectroscopy (MBS) and x-ray diffraction (XRD) before and after Fe-SOM extraction were used to assess changes in the mineralogical matrix associated with SOM dissolution, while N2-BET sorption was used to determine the contributions of the extractable phases to SSA. Results indicate (1) selective extraction of soil C produces significant shifts in Fe phase distribution, (2) SRO minerals contribute substantially to SSA, and (3) SRO minerals appear protected by more crystalline phases via physical mechanisms, rather than dissolution-dependent chemical bonds. This nanoscale characterization of Fe-C complexes thus provides evidence for both anticipated mineral-organic and

  12. Study of new complexes of uranium and comba radical. I.- Complexes defective in sodium carbonate; Estudio de nuevos complejos entre el uranio y el radical CDMBA. I. Complejos con defectos de carbonato sodico

    Energy Technology Data Exchange (ETDEWEB)

    Vera Palomino, J; Galiano Sedano, J A; Parellada Bellod, R; Bellido Gonzalez, A

    1975-07-01

    Some complexes formed in presence of defect of sodium carbonate with respect to the stoichiometric ratio (U): (C0{sub 3}) = 1:3 are studied. This ratio corresponds to the main complex which is responsible for the uranium extraction with CDMBAC organic solutions and from U(VI) aqueous solutions with an excess of sodium carbonate. (Author) 10 refs.

  13. Evidence of different stoichiometries for the limiting carbonate complexes of lanthanides(3); Mise en evidence d'un changement de stoechiometrie du complexe carbonate limite au sein de la serie des lanthanides(3)

    Energy Technology Data Exchange (ETDEWEB)

    Philippini, V

    2007-12-15

    Two stoichiometries have been proposed by different laboratories to interpret measurements on the limiting carbonate complexes of An{sup 3+} and Ln{sup 3+} cations. The study of the solubility of double carbonates (AlkLn(CO{sub 3}){sub 2},xH{sub 2}O) in concentrated carbonate solutions at room temperature and high ionic strengths has shown that on the one hand the lightest lanthanides (La and Nd) form Ln(CO{sub 3}){sub 4}{sup 5-} whereas the heaviest (Eu and Dy) form Ln(CO{sub 3}){sub 3}{sup 3-} in the studied chemical conditions, and on the other hand, that the kinetics of precipitation of double carbonates depends on the alkali metal and the lanthanide ions. The existence of two stoichiometries for the limiting carbonate complexes was confirmed by capillary electrophoresis hyphenated to an inductively coupled plasma mass spectrometer (CE-ICP-MS), used to extend the study to the whole series of lanthanides (except Ce, Pm and Yb). Two behaviours have been put forward comparing the electrophoretic mobilities: La to Tb form Ln(CO{sub 3}){sub 4}{sup 5-} while Dy to Lu form Ln(CO{sub 3}){sub 3}{sup 3-}. Measurements by time resolved laser fluorescence spectroscopy (TRLFS) on Eu(III) indicate small variations of the geometry of Eu(CO{sub 3}){sub 3}{sup 3-} complex, specially with Cs{sup +}. Although analogies are currently used among the 4f-block trivalent elements, different aqueous speciations are evidenced in concentrated carbonate solutions across the lanthanide series. (author)

  14. Electrochemical sensor for ranitidine determination based on carbon paste electrode modified with oxovanadium (IV) salen complex.

    Science.gov (United States)

    Raymundo-Pereira, Paulo A; Teixeira, Marcos F S; Fatibello-Filho, Orlando; Dockal, Edward R; Bonifácio, Viviane Gomes; Marcolino, Luiz H

    2013-10-01

    The preparation and electrochemical characterization of a carbon paste electrode modified with the N,N-ethylene-bis(salicyllideneiminato)oxovanadium (IV) complex ([VO(salen)]) as well as its application for ranitidine determination are described. The electrochemical behavior of the modified electrode for the electroreduction of ranitidine was investigated using cyclic voltammetry, and analytical curves were obtained for ranitidine using linear sweep voltammetry (LSV) under optimized conditions. The best voltammetric response was obtained for an electrode composition of 20% (m/m) [VO(salen)] in the paste, 0.10 mol L(-1) of KCl solution (pH 5.5 adjusted with HCl) as supporting electrolyte and scan rate of 25 mV s(-1). A sensitive linear voltammetric response for ranitidine was obtained in the concentration range from 9.9×10(-5) to 1.0×10(-3) mol L(-1), with a detection limit of 6.6×10(-5) mol L(-1) using linear sweep voltammetry. These results demonstrated the viability of this modified electrode as a sensor for determination, quality control and routine analysis of ranitidine in pharmaceutical formulations. Copyright © 2013. Published by Elsevier B.V.

  15. Deciphering Complex Carbon Cycle Changes Across the K-Pg Boundary Using Compound-Specific Carbon Isotopic Analyses

    Science.gov (United States)

    Pancost, R. D.; Taylor, K. W.; Hollis, C. J.; Crouch, E. M.

    2014-12-01

    The consequences of the Cretaceous-Paleogene (K/Pg) boundary event on the Earth system have been the subject of much scrutiny. Postulated climate events include a brief (10 - 2000 yr) period of global cooling induced by sulphate aerosols (the so-called 'impact winter'), an interval of warming caused by impact-induced CO2release, as well as longer-term climatic oscillations during the subsequent 1 to 3Myr. Associated with these were putative changes in the biogeochemical cycle, manifested as carbon isotope excursions on both short- and long-term timescales. In this study we develop new biomarker-based climate and biogeochemical records for the mid-Waipara River and Branch Stream sections, NZ. At Branch Stream, a pronounced negative (ca 6 to 8 permil) carbon isotope excursion occurs at the K/Pg; the excursion is recorded by higher plant biomarkers, consistent with some terrestrial records and suggesting that the immediate aftermath of the K/Pg boundary event was characterised by the massive release of 13C-depleted reduced carbon into the ocean-atmosphere reservoir. Mixing across the K/Pg boundary at the Waipara section precludes a similar high-resolution investigation. Lower-resolution, longer-term records, however, also reveal a negative carbon istope excursion documented by both algal and higher plant biomarkers. This event appears to be distinct from that recorded at Branch Stream, being of lower magnitude and longer duration. It coincided with a transient terrestrial and marine warming and appears to have lasted at least 100 kyr and perhaps longer. We argue that this protracted negative CIE reflects a secondary and longer-term consequence of the K/Pg on the global carbon cycle. There is little evidence for an algal extinction as a range of C27 to C30 sterols continued to be deposited throughout the entire section, but changes in GDGT distributions do suggest a change in carbon export dynamics which could have impacted burial of 13C-depleted marine organic matter

  16. Electron and ligand transfer reactions between cyclometallated platinum(II) compounds and thallium(III) carboxylates

    NARCIS (Netherlands)

    Koten, G. van; Ploeg, A.F.M.J. van der; Vrieze, K.

    1982-01-01

    Reaction of trans-[(2-Me{2}NCH{2}C{6}H{4}{2}Pt}I{}I{] with Tl}I{}I{}I{(O{2}CR){3} (R = Me, i-Pr) gave direct elimination of Tl}I{(O{2}CR) and formation of the oxidative addition product [(2-Me{2}NCH{2}C{6}H{4}){2}Pt}I{}V{ (O{2}CR){2}], in two isomeric forms. A structure with the carbon ligands in

  17. The surface chemistry of divalent metal carbonate minerals; a critical assessment of surface charge and potential data using the charge distribution multi-site ion complexation model

    NARCIS (Netherlands)

    Wolthers, M.; Charlet, L.; Van Cappellen, P.

    2008-01-01

    The Charge Distribution MUltiSite Ion Complexation or CD–MUSIC modeling approach is used to describe the chemical structure of carbonate mineralaqueous solution interfaces. The new model extends existing surface complexation models of carbonate minerals, by including atomic scale information on

  18. Carbonate formation within a nickel dimer: synthesis of a coordinatively unsaturated bis(mu-hydroxo) dinickel complex and its reactivity toward carbon dioxide.

    Science.gov (United States)

    Wikstrom, Jeffrey P; Filatov, Alexander S; Mikhalyova, Elena A; Shatruk, Michael; Foxman, Bruce M; Rybak-Akimova, Elena V

    2010-03-14

    The tridentate aminopyridine ligand bearing a bulky tert-butyl substituent at the amine nitrogen, tert-butyl-dipicolylamine (tBuDPA), occupies three coordination sites in six-coordinate complexes of nickel(ii), leaving the remaining three sites available for additional ligand binding and activation. New crystallographically characterized complexes include two mononuclear species with 1:1 metal:ligand complexation: a trihydrate solvate (1.3H(2)O) and a monohydrate biacetonitrile solvate (1.H(2)O.2CH(3)CN). Complexation in the presence of sodium hydroxide results in a bis(mu-hydroxo) complex (2), the bridging hydroxide anions of which are labile and become displaced by methoxide anions in methanol solvent, affording bis-methoxo-bridged (4). Nickel(II) centers in 2 are five-coordinate and antiferromagnetically coupled (with J = -31.4(5) cm(-1), H = -2JS(1)S(2), in agreement with Ni-O-Ni angle of 103.7 degrees). Bridging hydroxide or alkoxide anions in coordinatively unsaturated dinuclear nickel(II) complexes with tBuDPA react as active nucleophiles. 2 readily performs carbon dioxide fixation, resulting in the formation of a bis(mu-carbonato) tetrameric complex (3), which features a novel binding geometry in the form of an inverted butterfly-type nickel-carbonate core. Temperature-dependent magnetic measurements of tetranuclear carbonato-bridged revealed relatively weak antiferromagnetic coupling (J(1) = -3.1(2) cm(-1)) between the two nickel centers in the core of the cluster, as well as weak antiferromagnetic pairwise interactions (J(2) = J(3) = -4.54(5) cm(-1)) between central and terminal nickel ions.

  19. A novel non-enzymatic hydrogen peroxide sensor based on single walled carbon nanotubes-manganese complex modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, Abdollah, E-mail: absalimi@uok.ac.i [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Mahdioun, Monierosadat; Noorbakhsh, Abdollah [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Abdolmaleki, Amir [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156/83111 (Iran, Islamic Republic of); Ghavami, Raoof [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2011-03-30

    A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single wall carbon nanotubes (SWCNTs) and phenazine derivative of Mn-complex. With immersing the GC/CNTs modified electrode into Mn-complex solution for a short period of time 20-100 s, a stable thin layer of the complex was immobilized onto electrode surface. Modified electrode showed a well defined redox couples at wide pH range (1-12). The surface coverages and heterogeneous electron transfer rate constants (k{sub s}) of immobilized Mn-complex were approximately 1.58 x 10{sup -10} mole cm{sup -2} and 48.84 s{sup -1}. The modified electrode showed excellent electrocatalytic activity toward H{sub 2}O{sub 2} reduction. Detection limit, sensitivity, linear concentration range and k{sub cat} for H{sub 2}O{sub 2} were, 0.2 {mu}M and 692 nA {mu}M{sup -1} cm{sup -2}, 1 {mu}M to 1.5 mM and 7.96({+-}0.2) x 10{sup 3} M{sup -1} s{sup -1}, respectively. Compared to other modified electrodes, this electrode has many advantageous such as remarkable catalytic activity, good reproducibility, simple preparation procedure and long term stability.

  20. A novel non-enzymatic hydrogen peroxide sensor based on single walled carbon nanotubes-manganese complex modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Salimi, Abdollah; Mahdioun, Monierosadat; Noorbakhsh, Abdollah; Abdolmaleki, Amir; Ghavami, Raoof

    2011-01-01

    A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single wall carbon nanotubes (SWCNTs) and phenazine derivative of Mn-complex. With immersing the GC/CNTs modified electrode into Mn-complex solution for a short period of time 20-100 s, a stable thin layer of the complex was immobilized onto electrode surface. Modified electrode showed a well defined redox couples at wide pH range (1-12). The surface coverages and heterogeneous electron transfer rate constants (k s ) of immobilized Mn-complex were approximately 1.58 x 10 -10 mole cm -2 and 48.84 s -1 . The modified electrode showed excellent electrocatalytic activity toward H 2 O 2 reduction. Detection limit, sensitivity, linear concentration range and k cat for H 2 O 2 were, 0.2 μM and 692 nA μM -1 cm -2 , 1 μM to 1.5 mM and 7.96(±0.2) x 10 3 M -1 s -1 , respectively. Compared to other modified electrodes, this electrode has many advantageous such as remarkable catalytic activity, good reproducibility, simple preparation procedure and long term stability.

  1. Ruthenium-bipyridine complexes bearing fullerene or carbon nanotubes: synthesis and impact of different carbon-based ligands on the resulting products.

    Science.gov (United States)

    Wu, Zhen-yi; Huang, Rong-bin; Xie, Su-yuan; Zheng, Lan-sun

    2011-09-07

    This paper discusses the synthesis of two carbon-based pyridine ligands of fullerene pyrrolidine pyridine (C(60)-py) and multi-walled carbon nanotube pyrrolidine pyridine (MWCNT-py) via 1,3-dipolar cycloaddition. The two complexes, C(60)-Ru and MWCNT-Ru, were synthesized by ligand substitution in the presence of NH(4)PF(6), and Ru(II)(bpy)(2)Cl(2) was used as a reaction precursor. Both complexes were characterized by mass spectroscopy (MS), elemental analysis, nuclear magnetic resonance (NMR) spectroscopy, infrared spectroscopy (IR), ultraviolet/visible spectroscopy (UV-VIS) spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and cyclic voltammetry (CV). The results showed that the substitution way of C(60)-py is different from that of MWCNT-py. The C(60)-py and a NH(3) replaced a Cl(-) and a bipyridine in Ru(II)(bpy)(2)Cl(2) to produce a five-coordinate complex of [Ru(bpy)(NH(3))(C(60)-py)Cl]PF(6), whereas MWCNT-py replaced a Cl(-) to generate a six-coordinate complex of [Ru(bpy)(2)(MWCNT-py)Cl]PF(6). The cyclic voltammetry study showed that the electron-withdrawing ability was different for C(60) and MWCNT. The C(60) showed a relatively stronger electron-withdrawing effect with respect to MWCNT. This journal is © The Royal Society of Chemistry 2011

  2. Highly microporous carbons derived from a complex of glutamic acid and zinc chloride for use in supercapacitors

    Science.gov (United States)

    Dong, Xiao-Ling; Lu, An-Hui; He, Bin; Li, Wen-Cui

    2016-09-01

    The selection of carbon precursor is an important factor when designing carbon materials. In this study, a complex derived from L-glutamic acid and zinc chloride was used to prepare highly microporous carbons via facile pyrolysis. L-glutamic acid, a new carbon precursor with nitrogen functionality, coordinated with zinc chloride resulted in a homogeneous distribution of Zn2+ on the molecular level. During pyrolysis, the evaporation of the in situ formed zinc species creates an abundance of micropores together with the inert gases. The obtained carbons exhibit high specific surface area (SBET: 1203 m2 g-1) and a rich nitrogen content (4.52 wt%). In excess of 89% of the pore volume consists of micropores with pore size ranging from 0.5 to 1.2 nm. These carbons have been shown to be suitable for use as supercapacitor electrodes, and have been tested in 6 M KOH where a capacitance of 217 F g-1 was achieved at a current density of 0.5 A g-1. A long cycling life of 30 000 cycles was achieved at a current density of 1 A g-1, with only a 9% loss in capacity. The leakage current through a two-electrode device was measured as 2.3 μA per mg of electrode and the self-discharge characteristics were minimal.

  3. Serum albumin forms a lactoferrin-like soluble iron-binding complex in presence of hydrogen carbonate ions.

    Science.gov (United States)

    Ueno, Hiroshi M; Urazono, Hiroshi; Kobayashi, Toshiya

    2014-02-15

    The iron-lactoferrin complex is a common food ingredient because of its iron-solubilizing capability in the presence of hydrogen carbonate ions. However, it is unclear whether the formation of a stable iron-binding complex is limited to lactoferrin. In this study, we investigated the effects of bovine serum albumin (BSA) on iron solubility and iron-catalyzed lipid oxidation in the presence of hydrogen carbonate ions. BSA could solubilize >100-fold molar equivalents of iron at neutral pH, exceeding the specific metal-binding property of BSA. This iron-solubilizing capability of BSA was impaired by thermally denaturing BSA at ≥ 70 °C for 10 min at pH 8.5. The resulting iron-BSA complex inhibited iron-catalyzed oxidation of soybean oil in a water-in-oil emulsion measured using the Rancimat test. Our study is the first to show that BSA, like lactoferrin, forms a soluble iron-binding complex in the presence of hydrogen carbonate ions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Carbonate sedimentology of Seribu Islands patch reef complex: a literature review

    Science.gov (United States)

    Utami, D. A.; Hakim, A. R.

    2018-02-01

    Many oil and gas reservoirs in the world are reserved in fossil carbonate sediment. Knowledge of modern carbonate sedimentology is important for a better understanding of ancient carbonate sedimentation. Equatorial coral reefs comprise almost half of the world coral reef production, and yet their dynamics, distributions, and cycles are still not well understood. Contrary to their subtropical counterpart, South East Asian carbonate system is known to be strongly influenced by the combination of oceanographic and climatic conditions. Hence carbonate sediments in the tropics have a distinct depositional system, and ought to be treated differently since common distribution models were developed from the (sub-tropical) Atlantic and Pacific regions. This paper systematically summarizes carbonate sediment studies in Seribu Islands and its dominant oceanographic configuration to provide insights and a sense of research direction in the future.

  5. Influence of Beaver-Induced Complexity on Storage of Organic Carbon and Sediment in Colorado Mountain Streams

    Science.gov (United States)

    Laurel, D.; Wohl, E.

    2016-12-01

    Beaver meadows (complexes of multiple different aged beaver dams and ponds) influence the storage of water, sediment, and nutrients. Although beaver meadows compose only a small fraction of catchment area, they provide a potentially large role in retaining these fluxes in mountain watersheds. Multiple dams and ponds in beaver meadows increase overbank flows leading to an anastomosing stream channel planform, and deposition of fine sediment along with particulate organic carbon. An earlier study estimated a range of cumulative carbon stored in 27 beaver meadows east of the continental divide in Rocky Mountain National Park. Storage ranged from 735,800 to 2.8 x 106 Mg carbon, with the high value estimating storage if all the meadows had active beaver (historic conditions pre-European settlement) and the lower value estimating current conditions where many of the meadows are abandoned. We combined geomorphic surveys, soil depth probing by rebar, and soil cores analyzed for carbon content to investigate the influence of beaver activity, meadow size, and meadow placement within the drainage on catchment-scale fluxes of fine sediment and organic carbon. We found carbon storage in floodplain soils to be highly variable across both active and abandoned meadows; however, active beaver meadows store more carbon on average than abandoned meadows. In addition, active meadows with high levels of beaver activity (multiple colonies) stored greater volumes of fine sediment behind dams and in ponds. These results have implications for the restoration potential of abandoned beaver meadows in mountain environments to store greater volumes of sediment and more organic carbon if beaver are successfully reintroduced.

  6. Model complexity in carbon sequestration:A design of experiment and response surface uncertainty analysis

    Science.gov (United States)

    Zhang, Y.; Li, S.

    2014-12-01

    Geologic carbon sequestration (GCS) is proposed for the Nugget Sandstone in Moxa Arch, a regional saline aquifer with a large storage potential. For a proposed storage site, this study builds a suite of increasingly complex conceptual "geologic" model families, using subsets of the site characterization data: a homogeneous model family, a stationary petrophysical model family, a stationary facies model family with sub-facies petrophysical variability, and a non-stationary facies model family (with sub-facies variability) conditioned to soft data. These families, representing alternative conceptual site models built with increasing data, were simulated with the same CO2 injection test (50 years at 1/10 Mt per year), followed by 2950 years of monitoring. Using the Design of Experiment, an efficient sensitivity analysis (SA) is conducted for all families, systematically varying uncertain input parameters. Results are compared among the families to identify parameters that have 1st order impact on predicting the CO2 storage ratio (SR) at both end of injection and end of monitoring. At this site, geologic modeling factors do not significantly influence the short-term prediction of the storage ratio, although they become important over monitoring time, but only for those families where such factors are accounted for. Based on the SA, a response surface analysis is conducted to generate prediction envelopes of the storage ratio, which are compared among the families at both times. Results suggest a large uncertainty in the predicted storage ratio given the uncertainties in model parameters and modeling choices: SR varies from 5-60% (end of injection) to 18-100% (end of monitoring), although its variation among the model families is relatively minor. Moreover, long-term leakage risk is considered small at the proposed site. In the lowest-SR scenarios, all families predict gravity-stable supercritical CO2 migrating toward the bottom of the aquifer. In the highest

  7. Adsorption of Pb{sup 2+} and Cd{sup 2+} onto a novel activated carbon-chitosan complex

    Energy Technology Data Exchange (ETDEWEB)

    Ge, H.; Fan, X. [College of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China)

    2011-10-15

    A novel activated carbon-chitosan complex adsorbent (ACCA) was prepared via the crosslinking of glutaraldehyde and activated carbon-(NH{sub 2}-protected) chitosan complex under microwave irradiation. The surface morphology of this adsorbent was characterized. The adsorption of ACCA for Pb{sup 2+} and Cd{sup 2+} was investigated. The results demonstrate that ACCA has higher adsorption capacity than chitosan. The adsorption follows pseudo first-order kinetics. The isotherm adsorption equilibria are better described by Freundlich and Dubinin-Radushkevich isotherms than by the Langmuir isotherm. The adsorbent can be recycled. These results have important implications for the design of low-cost and effective adsorbents in the removal of heavy metal ions from wastewaters. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Bifacial dye-sensitized solar cells from covalent-bonded polyaniline-multiwalled carbon nanotube complex counter electrodes

    Science.gov (United States)

    Zhang, Huihui; He, Benlin; Tang, Qunwei; Yu, Liangmin

    2015-02-01

    Exploration of cost-effective counter electrodes (CEs) and enhancement of power conversion efficiency have been two persistent objectives for dye-sensitized solar cells (DSSCs). In the current work, polyaniline-multiwalled carbon nanotube (PANi-MWCNT) complexes are synthesized by a reflux method and employed as CE materials for bifacial DSSCs. Owing to the high optical transparency of PANi-MWCNT complex CE, the incident light from rear side can compensate for the incident light from TiO2 anode. The charge-transfer ability and electrochemical behaviors demonstrate the potential utilization of PANi-MWCNT complex CEs in robust bifacial DSSCs. The electrochemical properties as well as photovoltaic performances are optimized by adjusting MWCNT dosages. A maximum power conversion efficiency of 9.24% is recorded from the bifacial DSSC employing PANi-8 wt‰ MWCNT complex CE for both irradiation, which is better than 8.08% from pure PANi CE.

  9. Electrosorption of Os(III)-complex at single-wall carbon nanotubes immobilized on a glassy carbon electrode: Application to nanomolar detection of bromate, periodate and iodate

    International Nuclear Information System (INIS)

    Salimi, Abdollah; Kavosi, Begard; Babaei, Ali; Hallaj, Rahman

    2008-01-01

    A simple procedure was developed to prepare a glassy carbon electrode modified with single-wall carbon nanotubes (SWCNTs) and Os(III)-complex. The glassy carbon (GC) electrode modified with CNTs was immersed into Os(III)-complex solution (direct deposition) for a short period of time (60 s). 1,4,8,12-Tetraazacyclotetradecane osmium(III) chloride, (Os(III)LCl 2 ).ClO 4 , irreversibly and strongly adsorbed on SWCNTs immobilized on the surface of GC electrode. Cyclic voltammograms of the Os(III)-complex-incorporated-SWCNTs indicate a pair of well defined and nearly reversible redox couple with surface confined characteristic at wide pH range (1-8). The surface coverage (Γ) and charge transfer rate constant (k s ) of the immobilized Os-complex on SWCNTs were 3.07 x 10 -9 mol cm -2 , 5.5 (±0.2) s -1 , 2.94 x 10 -9 mol cm -2 , 7.3 (±0.3) s -1 at buffer solution with pH 2 and 7, respectively, indicate high loading ability of SWCNTs for Os(III) complex and great facilitation of the electron transfer between electroactive redox center and carbon nanotubes immobilized on the electrode surface. Modified electrodes showed higher electrocatalytic activity toward reduction of BrO 3 - , IO 3 - and IO 4 - in acidic solutions. The catalytic rate constants for catalytic reduction bromate, periodate and iodate were 3.79 (±0.2) x 10 3 , 7.32 (±0.2) x 10 3 and 1.75 (±0.2) x 10 3 M -1 s -1 , respectively. The hydrodynamic amperometry of rotating modified electrode at constant potential (0.3 V) was used for nanomolar detection of selected analytes. Excellent electrochemical reversibility of the redox couple, good reproducibility, high stability, low detection limit, long life time, fast amperometric response time, wide linear concentration range, technical simplicity and possibility of rapid preparation are great advantage of this sensor

  10. Carbon-13 magnetic relaxation rates or iron (III) complexes of some biogenic amines and parent compounds in aqueous solutions

    International Nuclear Information System (INIS)

    Lai, A.; Monduzzi, M.; Saba, G.

    1980-01-01

    Spin-lattice relaxation rates (R 1 ) from naturally occuring C-13 F.T. N.M.R. spectra of some catecholamines and parent compounds with Iron(III) at pD = 4 were determined in order to elucidate the molecular mechanism underlying their association in aqueous solutions. Complexation was observed only for catecholic ligands. The R 1 values were used to calculate iron-carbon scaled distances, and two complexation models were proposed where the catecholic function binds Fe(III) in the first and second coordination spheres respectively. The latter case was shown to be the consistent with the molecular geometries. (orig.)

  11. A glassy carbon electrode modified with a nickel(II) norcorrole complex and carbon nanotubes for simultaneous or individual determination of ascorbic acid, dopamine, and uric acid

    International Nuclear Information System (INIS)

    Deng, Keqin; Li, Xiaofang; Huang, Haowen

    2016-01-01

    The authors report on the synthesis of a hybrid material consisting of the porphyrinoid metal complex nickel(II) norcorrole that was noncovalently bound to carbon nanotubes (CNT-NiNC). The hybrid was characterized by UV–vis, FTIR spectroscopy, and thermogravimetric analysis. The CNT-NiNC hybrid possesses high catalytic activity and selectivity toward the oxidation of ascorbic acid, dopamine, and uric acid. It was used to modify a glassy carbon electrode which then is shown to enable simultaneous or individual determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) at pH 6.5 and typical working potentials of −70, 200 and 380 mV (vs. SCE). The detection limits (at an SNR of 3) are 2.0 μM for AA, 0.1 μM for DA, and 0.4 μM for UA. (author)

  12. Influence of carbonate on the complexation of Cm(III) with human serum transferrin studied by time-resolved laser fluorescence spectroscopy (TRLFS)

    International Nuclear Information System (INIS)

    Bauer, Nicole; Panak, Petra J.

    2015-01-01

    The complexation of Cm(III) with transferrin is investigated in the pH range from 3.5 to 11.0 in the absence of carbonate and at c(carbonate)(tot) = 25 mM. In the absence of carbonate two Cm(III) transferrin species I and II are formed depending on pH. An increase of the total carbonate concentration favors the formation of the Cm(III) transferrin species II with Cm(III) bound at the Fe(III) binding site of transferrin at significantly lower pH values. The spectroscopic results directly prove that carbonate acts as a synergistic anion for Cm(III) complexation at the binding site of transferrin. At c(carbonate)(tot) = 25 mM the formation of the nonspecific Cm(III) transferrin species I is suppressed completely. Instead, three Cm(III) carbonate species Cm(CO 3 ) + , Cm(CO 3 ) 2 - and Cm(CO 3 ) 3 3- are formed successively with increasing pH. The formation of Cm(III) carbonate species results in a decreased fraction of the Cm(III) transferrin species II at pH ≥ 7.4 which indicates that carbonate complexation is an important competition reaction for Cm(III) transferrin complexation at physiological carbonate concentration. (authors)

  13. Atomistic materials modeling of complex systems: Carbynes, carbon nanotube devices and bulk metallic glasses

    Science.gov (United States)

    Luo, Weiqi

    The key to understanding and predicting the behavior of materials is the knowledge of their structures. Many properties of materials samples are not solely determined by their average chemical compositions which one may easily control. Instead, they are profoundly influenced by structural features of different characteristic length scales. Starting in the last century, metallurgical engineering has mostly been microstructure engineering. With the further evolution of materials science, structural features of smaller length scales down to the atomic structure, have become of interest for the purpose of properties engineering and functionalizing materials and are, therefore, subjected to study. As computer modeling is becoming more powerful due to the dramatic increase of computational resources and software over the recent decades, there is an increasing demand for atomistic simulations with the goal of better understanding materials behavior on the atomic scale. Density functional theory (DFT) is a quantum mechanics based approach to calculate electron distribution, total energy and interatomic forces with high accuracy. From these, atomic structures and thermal effects can be predicted. However, DFT is mostly applied to relatively simple systems because it is computationally very demanding. In this thesis, the current limits of DFT applications are explored by studying relatively complex systems, namely, carbynes, carbon nanotube (CNT) devices and bulk metallic glasses (BMGs). Special care is taken to overcome the limitations set by small system sizes and time scales that often prohibit DFT from being applied to realistic systems under realistic external conditions. In the first study, we examine the possible existence of a third solid phase of carbon with linear bonding called carbyne, which has been suggested in the literature and whose formation has been suggested to be detrimental to high-temperature carbon materials. We have suggested potential structures for

  14. Novel in situ multiharmonic EQCM-D approach to characterize complex carbon pore architectures for capacitive deionization of brackish water

    International Nuclear Information System (INIS)

    Shpigel, Netanel; Levi, Mikhael D; Sigalov, Sergey; Aurbach, Doron; Daikhin, Leonid; Presser, Volker

    2016-01-01

    Multiharmonic analysis by electrochemical quartz-crystal microbalance with dissipation monitoring (EQCM-D) is introduced as an excellent tool for quantitative studying electrosorption of ions from aqueous solution in mesoporous (BP-880) or mixed micro-mesoporous (BP-2000) carbon electrodes. Finding the optimal conditions for gravimetric analysis of the ionic content in the charged carbon electrodes, we propose a novel approach to modeling the charge-dependent gravimetric characteristics by incorporation of Gouy-Chapman-Stern electric double layer model for ions electrosorption into meso- and micro-mesoporous carbon electrodes. All three parameters of the gravimetric equation evaluated by fitting it to the experimental mass changes curves were validated using supplementary nitrogen gas sorption analysis and complementing atomic force microscopy. Important overlap between gravimetric EQCM-D analysis of the ionic content of porous carbon electrodes and the classical capacitive deionization models has been established. The necessity and usefulness of non-gravimetric EQCM-D characterizations of complex carbon architectures, providing insight into their unique viscoelastic behavior and porous structure changes, have been discussed in detail. (paper)

  15. Carbon-water Cycling in the Critical Zone: Understanding Ecosystem Process Variability Across Complex Terrain

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, Holly [Univ. of Colorado, Boulder, CO (United States); Brooks, Paul [Univ. of Utah, Salt Lake City, UT (United States); Univ. of Arizona, Tucson, AZ (United States)

    2016-06-16

    One of the largest knowledge gaps in environmental science is the ability to understand and predict how ecosystems will respond to future climate variability. The links between vegetation, hydrology, and climate that control carbon sequestration in plant biomass and soils remain poorly understood. Soil respiration is the second largest carbon flux of terrestrial ecosystems, yet there is no consensus on how respiration will change as water availability and temperature co-vary. To address this knowledge gap, we use the variation in soil development and topography across an elevation and climate gradient on the Front Range of Colorado to conduct a natural experiment that enables us to examine the co-evolution of soil carbon, vegetation, hydrology, and climate in an accessible field laboratory. The goal of this project is to further our ability to combine plant water availability, carbon flux and storage, and topographically driven hydrometrics into a watershed scale predictive model of carbon balance. We hypothesize: (i) landscape structure and hydrology are important controls on soil respiration as a result of spatial variability in both physical and biological drivers: (ii) variation in rates of soil respiration during the growing season is due to corresponding shifts in belowground carbon inputs from vegetation; and (iii) aboveground carbon storage (biomass) and species composition are directly correlated with soil moisture and therefore, can be directly related to subsurface drainage patterns.

  16. GLUT1-mediated selective tumor targeting with fluorine containing platinum(II) glycoconjugates.

    Science.gov (United States)

    Liu, Ran; Fu, Zheng; Zhao, Meng; Gao, Xiangqian; Li, Hong; Mi, Qian; Liu, Pengxing; Yang, Jinna; Yao, Zhi; Gao, Qingzhi

    2017-06-13

    Increased glycolysis and overexpression of glucose transporters (GLUTs) are physiological characteristics of human malignancies. Based on the so-called Warburg effect, 18flurodeoxyglucose-positron emission tomography (FDG-PET) has successfully developed as clinical modality for the diagnosis and staging of many cancers. To leverage this glucose transporter mediated metabolic disparity between normal and malignant cells, in the current report, we focus on the fluorine substituted series of glucose, mannose and galactose-conjugated (trans-R,R-cyclohexane-1,2-diamine)-2-flouromalonato-platinum(II) complexes for a comprehensive evaluation on their selective tumor targeting. Besides highly improved water solubility, these sugar-conjugates presented improved cytotoxicity than oxaliplatin in glucose tranporters (GLUTs) overexpressing cancer cell lines and exhibited no cross-resistance to cisplatin. For the highly water soluble glucose-conjugated complex (5a), two novel in vivo assessments were conducted and the results revealed that 5a was more efficacious at a lower equitoxic dose (70% MTD) than oxaliplatin (100% MTD) in HT29 xenograft model, and it was significantly more potent than oxaliplatin in leukemia-bearing DBA/2 mice as well even at equimolar dose levels (18% vs 90% MTD). GLUT inhibitor mediated cell viability analysis, GLUT1 knockdown cell line-based cytotoxicity evaluation, and platinum accumulation study demonstrated that the cellular uptake of the sugar-conjugates was regulated by GLUT1. The higher intrinsic DNA reactivity of the sugar-conjugates was confirmed by kinetic study of platinum(II)-guanosine adduct formation. The mechanistic origin of the antitumor effect of the fluorine complexes was found to be forming the bifunctional Pt-guanine-guanine (Pt-GG) intrastrand cross-links with DNA. The results provide a rationale for Warburg effect targeted anticancer drug design.

  17. An investigation of groundwater organics, soil minerals, and activated carbon on the complexation, adsorption, and separation of technetium-99

    International Nuclear Information System (INIS)

    Gu, B.

    1996-01-01

    This report summarizes studies on the interactions of technetium-99 (Tc) with different organic compounds and soil minerals under both oxidizing and reducing conditions. The report is divided into four parts and includes (1) effect of natural organic matter (NOM) on the complexation and solubility of Tc, (2) complexation between Tc and trichloroethylene (TCE) in aqueous solutions, (3) adsorption of Tc on soil samples from Paducah Gaseous Diffusion Plant (PGDP), and (4) adsorption and separation of Tc on activated carbon. Various experimental techniques were applied to characterize and identify Tc complexation with organic compounds and TCE, including liquid-liquid extraction, membrane filtration, size exclusion, and gel chromatography. Results indicate, within the experimental error, Tc (as pertechnetate, TcO 4 ) did not appear to form complexes with groundwater or natural organic matter under both atmospheric and reducing conditions. However, Tc can form complexes with certain organic compounds or specific functional groups such as salicylate. Tc did not appear to form complexes with TCE in aqueous solution.Both liquid-liquid extraction and high performance liquid chromatography (HPLC) gave no indication Tc was complexed with TCE. The correlations between Tc and TCE concentrations in monitoring wells at PGDP may be a coincidence because TCE was commonly used as a decontamination reagent. Once TCE and Tc entered the groundwater, they behaved similarly because both TcO 4 - and TCE are poorly adsorbed by soils. An effective remediation technique to remove TcO 4 - from PGDP contaminated groundwater is needed. One possibility is the use of an activated carbon adsorption technique developed in this study

  18. Two different carbon-hydrogen complexes in silicon with closely spaced energy levels

    Energy Technology Data Exchange (ETDEWEB)

    Stübner, R., E-mail: ronald.stuebner@physik.tu-dresden.de, E-mail: kolkov@ifpan.edu.pl; Kolkovsky, Vl., E-mail: ronald.stuebner@physik.tu-dresden.de, E-mail: kolkov@ifpan.edu.pl; Weber, J. [Technische Universität Dresden, Institut für Angewandte Physik, 01062 Dresden (Germany)

    2015-08-07

    An acceptor and a single donor state of carbon-hydrogen defects (CH{sub A} and CH{sub B}) are observed by Laplace deep level transient spectroscopy at 90 K. CH{sub A} appears directly after hydrogenation by wet chemical etching or hydrogen plasma treatment, whereas CH{sub B} can be observed only after a successive annealing under reverse bias at about 320 K. The activation enthalpies of these states are 0.16 eV for CH{sub A} and 0.14 eV for CH{sub B}. Our results reconcile previous controversial experimental results. We attribute CH{sub A} to the configuration where substitutional carbon binds a hydrogen atom on a bond centered position between carbon and the neighboring silicon and CH{sub B} to another carbon-hydrogen defect.

  19. Complex formation during dissolution of metal oxides in molten alkali carbonates

    DEFF Research Database (Denmark)

    Li, Qingfeng; Borup, Flemming; Petrushina, Irina

    1999-01-01

    Dissolution of metal oxides in molten carbonates relates directly to the stability of materials for electrodes and construction of molten carbonate fuel cells. In the present work the solubilities of PbO, NiO, Fe2O3,and Bi2O3 in molten Li/K carbonates have been measured at 650 degrees C under...... carbon dioxide atmosphere. It is found that the solubilities of NiO and PbO decrease while those of Fe2O3 and Bi2O3 remain approximately constant as the lithium mole fraction increases from 0.43 to 0.62 in the melt. At a fixed composition of the melt, NiO and PbO display both acidic and basic dissolution...

  20. Adsorption of chromium complex dye and copper(II) ions by activated carbons

    OpenAIRE

    Česūnienė, Rasa

    2013-01-01

    In recent decades, more and more attention is paid to the environment protection because of the emission of large quantities of solid, liquid and gaseous waste from many manufacturing processes. They cause the environmental pollution and are harmful to human health. The commercial activated carbons (CAC) are widely used for drinking water and waste water treatment. Activated carbon is a form of graphite, which is characterized by irregular or amorphous structure, with varying sizes - from the...

  1. Symmetry and structure of carbon-nitrogen complexes in gallium arsenide from infrared spectroscopy and first-principles calculations

    Science.gov (United States)

    Künneth, Christopher; Kölbl, Simon; Wagner, Hans Edwin; Häublein, Volker; Kersch, Alfred; Alt, Hans Christian

    2018-04-01

    Molecular-like carbon-nitrogen complexes in GaAs are investigated both experimentally and theoretically. Two characteristic high-frequency stretching modes at 1973 and 2060 cm-1, detected by Fourier transform infrared absorption (FTIR) spectroscopy, appear in carbon- and nitrogen-implanted and annealed layers. From isotopic substitution, it is deduced that the chemical composition of the underlying complexes is CN2 and C2N, respectively. Piezospectroscopic FTIR measurements reveal that both centers have tetragonal symmetry. For density functional theory (DFT) calculations, linear entities are substituted for the As anion, with the axis oriented along the 〈1 0 0 〉 direction, in accordance with the experimentally ascertained symmetry. The DFT calculations support the stability of linear N-C-N and C-C-N complexes in the GaAs host crystal in the charge states ranging from + 3 to -3. The valence bonds of the complexes are analyzed using molecular-like orbitals from DFT. It turns out that internal bonds and bonds to the lattice are essentially independent of the charge state. The calculated vibrational mode frequencies are close to the experimental values and reproduce precisely the isotopic mass splitting from FTIR experiments. Finally, the formation energies show that under thermodynamic equilibrium CN2 is more stable than C2N.

  2. The distribution and amount of carbon in the largest peatland complex in Amazonia

    International Nuclear Information System (INIS)

    Draper, Frederick C; Baker, Timothy R; Roucoux, Katherine H; Lawson, Ian T; Mitchard, Edward T A; Honorio Coronado, Euridice N; Zaráte, Ricardo; Lähteenoja, Outi; Torres Montenegro, Luis; Valderrama Sandoval, Elvis

    2014-01-01

    Peatlands in Amazonian Peru are known to store large quantities of carbon, but there is high uncertainty in the spatial extent and total carbon stocks of these ecosystems. Here, we use a multi-sensor (Landsat, ALOS PALSAR and SRTM) remote sensing approach, together with field data including 24 forest census plots and 218 peat thickness measurements, to map the distribution of peatland vegetation types and calculate the combined above- and below-ground carbon stock of peatland ecosystems in the Pastaza-Marañon foreland basin in Peru. We find that peatlands cover 35 600 ± 2133 km 2 and contain 3.14 (0.44–8.15) Pg C. Variation in peat thickness and bulk density are the most important sources of uncertainty in these values. One particular ecosystem type, peatland pole forest, is found to be the most carbon-dense ecosystem yet identified in Amazonia (1391 ± 710 Mg C ha −1 ). The novel approach of combining optical and radar remote sensing with above- and below-ground carbon inventories is recommended for developing regional carbon estimates for tropical peatlands globally. Finally, we suggest that Amazonian peatlands should be a priority for research and conservation before the developing regional infrastructure causes an acceleration in the exploitation and degradation of these ecosystems. (letter)

  3. About the structure and stability of complex carbonates of thorium (IV), cerium (IV), zirconium (IV), hafnium (IV)

    International Nuclear Information System (INIS)

    Dervin, Jacqueline

    1972-01-01

    This research thesis addressed the study of complex carbonates of cations of metals belonging to the IV A column, i.e. thorium (IV), zirconium (IV), hafnium (IV), and also cerium (IV) and uranium (VI), and more particularly focused on ionic compounds formed in solution, and also on the influence of concentration and nature of cations on stability and nature of the formed solid. The author first presents methods used in this study, discusses their precision and scope of validity. She reports the study of the formation of different complex ions which have been highlighted in solution, and the determination of their formation constants. She reports the preparation and study of the stability domain of solid complexes. The next part reports the use of thermogravimetric analysis, IR spectrometry, and crystallography for the structural study of these compounds

  4. Stability constants important to the understanding of plutonium in environmental waters, hydroxy and carbonate complexation of PuO2+

    International Nuclear Information System (INIS)

    Bennett, D.A.; Lawrence Berkeley Lab., CA

    1990-01-01

    The formation constants for the reactions PuO 2 + + H 2 O = PuO 2 (OH) + H + and PuO 2 + + CO 3 2 = PuO 2 (CO 3 ) - were determined in aqueous sodium perchlorate solutions by laser-induced photoacoustic spectroscopy. The molar absorptivity of the PuO 2 + band at 569 nm decreased with increasing hydroxide concentration. Similarly, spectral changes occurred between 540 and 580 nm as the carbonate concentration was increased. The absorption data were analyzed by the non-linear least-squares program SQUAD to yield complexation constants. Using the specific ion interaction theory, both complexation constants were extrapolated to zero ionic strength. These thermodynamic complexation constants were combined with the oxidation-reduction potentials of Pu to obtain Eh versus pH diagrams. 120 refs., 35 figs., 12 tabs

  5. Response of the carbon cycle in an intermediate complexity model to the different climate configurations of the last nine interglacials

    Science.gov (United States)

    Bouttes, Nathaelle; Swingedouw, Didier; Roche, Didier M.; Sanchez-Goni, Maria F.; Crosta, Xavier

    2018-03-01

    Atmospheric CO2 levels during interglacials prior to the Mid-Brunhes Event (MBE, ˜ 430 ka BP) were around 40 ppm lower than after the MBE. The reasons for this difference remain unclear. A recent hypothesis proposed that changes in oceanic circulation, in response to different external forcings before and after the MBE, might have increased the ocean carbon storage in pre-MBE interglacials, thus lowering atmospheric CO2. Nevertheless, no quantitative estimate of this hypothesis has been produced up to now. Here we use an intermediate complexity model including the carbon cycle to evaluate the response of the carbon reservoirs in the atmosphere, ocean and land in response to the changes of orbital forcings, ice sheet configurations and atmospheric CO2 concentrations over the last nine interglacials. We show that the ocean takes up more carbon during pre-MBE interglacials in agreement with data, but the impact on atmospheric CO2 is limited to a few parts per million. Terrestrial biosphere is simulated to be less developed in pre-MBE interglacials, which reduces the storage of carbon on land and increases atmospheric CO2. Accounting for different simulated ice sheet extents modifies the vegetation cover and temperature, and thus the carbon reservoir distribution. Overall, atmospheric CO2 levels are lower during these pre-MBE simulated interglacials including all these effects, but the magnitude is still far too small. These results suggest a possible misrepresentation of some key processes in the model, such as the magnitude of ocean circulation changes, or the lack of crucial mechanisms or internal feedbacks, such as those related to permafrost, to fully account for the lower atmospheric CO2 concentrations during pre-MBE interglacials.

  6. Electrocatalytic and simultaneous determination of isoproterenol, uric acid and folic acid at molybdenum (VI) complex-carbon nanotube paste electrode

    International Nuclear Information System (INIS)

    Beitollahi, Hadi; Sheikhshoaie, Iran

    2011-01-01

    Highlights: → A molybdenum (VI) complex-carbon nanotube paste electrode have been fabricated. → This electrode reduced the oxidation potential of isoproterenol by about 175 mV. → It resolved the voltammetric waves of isoproterenol, uric acid and folic acid. - Abstract: This paper describes the development, electrochemical characterization and utilization of a novel modified molybdenum (VI) complex-carbon nanotube paste electrode for the electrocatalytic determination of isoproterenol (IP). The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV) that showed a shift of the oxidation peak potential of IP at 175 mV to less positive value, compared with an unmodified carbon paste electrode. Differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed to determine IP in the range from 0.7 to 600.0 μM, with a detection limit of 35.0 nM. Then the modified electrode was used to determine IP in an excess of uric acid (UA) and folic acid (FA) by DPV. Finally, this method was used for the determination of IP in some real samples.

  7. Chemical behaviour of plutonium in natural, aquatic systems: Hydrolysis, carbonate complexation and redox reactions

    International Nuclear Information System (INIS)

    Lierse, C.

    1985-01-01

    In order to clear up the geochemical behaviour of plutonium and its migration mechanisms in groundwater, hydrolysis, redox behaviour, compound formation in carbonate solutions and colloid formation were examined in groundwater conditions, i.e. at pH values between 5 and 8 and at redox potentials of between -300 and +700 mV. Solubility measurements, spectroscopic processes (UV, VIS, IR spectroscopy and laser induced photoacoustic spectroscopy) and electrochemical processes (cyclic voltammetry, differential pulse polarography) are used as methods of investigation. The hydrolysis constants of Pu IV and Pu VI and the solubility product of Pu (OH) 4 were determined and hydrolysis products of divalent and trivalent type are described. From solubility experiments, the stability constants for Pu (IV) carbonate compounds and the solubility product for the carbonate system of stable bodies of Pu (OH) 2 CO 3 were calculated. Using absorption spectroscopy, the disproportionate kinetics of Pu (V) in carbonate was determined at various pH values. A slow, but continuous, reduction in Pu (VI) was found in carbonate solution, which was derived from radiolytic effects. The speed of this auto-reduction was determined, depending on various experimental parameters. (orig./RB) [de

  8. Quantum-Chemical Insights into the Self-Assembly of Carbon-Based Supramolecular Complexes

    Directory of Open Access Journals (Sweden)

    Joaquín Calbo

    2018-01-01

    Full Text Available Understanding how molecular systems self-assemble to form well-organized superstructures governed by noncovalent interactions is essential in the field of supramolecular chemistry. In the nanoscience context, the self-assembly of different carbon-based nanoforms (fullerenes, carbon nanotubes and graphene with, in general, electron-donor molecular systems, has received increasing attention as a means of generating potential candidates for technological applications. In these carbon-based systems, a deep characterization of the supramolecular organization is crucial to establish an intimate relation between supramolecular structure and functionality. Detailed structural information on the self-assembly of these carbon-based nanoforms is however not always accessible from experimental techniques. In this regard, quantum chemistry has demonstrated to be key to gain a deep insight into the supramolecular organization of molecular systems of high interest. In this review, we intend to highlight the fundamental role that quantum-chemical calculations can play to understand the supramolecular self-assembly of carbon-based nanoforms through a limited selection of supramolecular assemblies involving fullerene, fullerene fragments, nanotubes and graphene with several electron-rich π-conjugated systems.

  9. The Oligocene carbonate platform of the Zagros Basin, SW Iran: An assessment of highly-complex geological heritage

    Science.gov (United States)

    Habibi, Tahereh; Ruban, Dmitry A.

    2017-05-01

    North Africa and the Middle East possess rich geological heritage, but the latter is yet to be fully identified and described. The Oligocene carbonate platform of the Zagros Basin in southwest Iran, which corresponds to the lower part of the Asmari Formation, has significant potential for geoconservation and geotourism. The types of the geological heritage, their value, and the possible geosites have been assessed. The studied deposits are interesting because of lithology (carbonate rocks), fossils (larger foraminifera, other microfossils, diverse marine invertebrates, fish microremains, and trace fossils), biostratigraphical developments, facies (homoclinal carbonate ramp) and signature of global events (glacioeustatic fluctuations), and outstanding hydrocarbon resources. The five main geological heritage types are sedimentary, palaeontological, stratigraphical, palaeogeographical, and economical, from which the palaeontological, palaeogeographical, and economical types are of global rank. The Khollar and Kavar sections in the Fars Province of Iran are recommended as geosites suitable for research, education, and tourism. The high complexity of the geological heritage linked to the Oligocene carbonate platform of the Zagros Basin implies the phenomenon of geodiversity should be understood with regard to the relationships between types and their values.

  10. Correction: A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-12-22

    Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.

  11. Final Report: Optimal Model Complexity in Geological Carbon Sequestration: A Response Surface Uncertainty Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ye [Univ. of Wyoming, Laramie, WY (United States)

    2018-01-17

    equivalency, all the stratigraphic models were successfully upscaled from the reference heterogeneous model for bulk flow and transport predictions (Zhang & Zhang, 2015). GCS simulation was then simulated with all models, yielding insights into the level of parameterization complexity that is needed for the accurate simulation of reservoir pore pressure, CO2 storage, leakage, footprint, and dissolution over both short (i.e., injection) and longer (monitoring) time scales. Important uncertainty parameters that impact these key performance metrics were identified for the stratigraphic models as well as for the heterogeneous model, leading to the development of reduced/simplified models at lower characterization cost that can be used for the reservoir uncertainty analysis. All the CO2 modeling was conducted using PFLOTRAN – a massively parallel, multiphase, multi-component, and reactive transport simulator developed by a multi-laboratory DOE/SciDAC (Scientific Discovery through Advanced Computing) project (Zhang et al., 2017, in review). Within the uncertainty analysis framework, increasing reservoir depth were investigated to explore its effect on the uncertainty outcomes and the potential for developing gravity-stable injection with increased storage security (Dai et al., 20126; Dai et al., 2017, in review). Finally, to accurately model CO2 fluid-rock reactions and resulting long-term storage as secondary carbonate minerals, a modified kinetic rate law for general mineral dissolution and precipitation was proposed and verified that is invariant to a scale transformation of the mineral formula weight. This new formulation will lead to more accurate assessment of mineral storage over geologic time scales (Lichtner, 2016).

  12. Spectrophotometric Analysis of the Kinetic of Pd(II Chloride Complex Ions Sorption Process from Diluted Aqua Solutions Using Commercially Available Activated Carbon

    Directory of Open Access Journals (Sweden)

    Wojnicki M.

    2017-12-01

    Full Text Available In this paper, results of adsorption kinetic studies of Pd(II chloride complex ions on activated carbon Organosrob 10 CO are presented. Spectorphotometrical method was applied to investigate the process. Kinetic model was proposed, and fundamental thermodynamic parameters were determined. Proposed kinetic model describes well observed phenomenon in the studied range of concentration of Pd(II chloride complex ions as well, as concentration of activated carbon.

  13. An efficient polymeric micromotor doped with Pt nanoparticle@carbon nanotubes for complex bio-media.

    Science.gov (United States)

    Li, Yana; Wu, Jie; Xie, Yuzhe; Ju, Huangxian

    2015-04-14

    A highly efficient polymeric tubular micromotor doped with Pt nanoparticle@carbon nanotubes is fabricated by template-assisted electrochemical growth. The micromotors preserve good navigation in multi-media and surface modification, along with simple synthesis, easy functionalization and good biocompatibility, displaying great promise in biological applications.

  14. Modeling complex effects of multiple environmental stresses on carbon dynamics of Mid-Atlantic temperate forests

    Science.gov (United States)

    Yude Pan; Richard Birdsey; John Hom; Kevin McCullough

    2007-01-01

    We used our GIS variant of the PnET-CN model to investigate changes of forest carbon stocks and fluxes in Mid-Atlantic temperate forests over the last century (1900-2000). Forests in this region are affected by multiple environmental changes including climate, atmospheric CO2 concentration, N deposition and tropospheric ozone, and extensive land disturbances. Our...

  15. From simple to complex prebiotic chemistry in a carbon-rich universe

    Science.gov (United States)

    Lage, C.; Janot-Pacheco, E.; Domiciano de Souza, A.; Suárez, O.; Bendjoya, P.; Gadotti, D. A.

    2012-09-01

    It is well known that the main components of important biomolecules are quite common not only in the Solar System, but also in other planetary systems and in the Galactic ISM. The ubiquitous presence of C in the Universe and the unique carbon chemical properties and carbon bonding thermodynamics supports the spontaneous self-replication of monomers into larger polymers, yielding the formation of large molecules. The detection of an ever increasing number of organic molecules in the interstellar medium (ISM) by radio-telescopes and chemical analysis of meteorites boosted astrochemical theories on radiation-induced chemistry, supported by laboratory experiments. In this scenario of exogenous origin of carbon compounds, polyaromatic hydrocarbons (PAHs) may represent a resilient way of accumulating carbon as a robust cosmic reservoir. Consisting of a family of compounds with fused aromatic rings, the abundances of its larger members (50-100 carbon atoms) were estimated to be on top scores just after H2 and CO. PAHs have been detected in the ISM, in star-forming regions, ~14% of low-mass premainsequence stars, and, remarkably, in some 54% of intermediate mass stars. They have also been detected by SPITZER in distant galaxies up to z = 3. PAHs were promptly photolysed into a family of radicals if exposed to UV and oxygen-bearing molecules in laboratory. The presence of oxygenbearing molecules was shown in the laboratory to bring aromatic rings into an unstable chemistry leading to the production of e.g. alcohols, ketones and ether radicals. It has already been observed that carbon-and oxygen-rich stellar envelopes give rise to richer carbon chemistry. It appears very tempting to think that key prebiotic fragments should appear along planetary formation as C-O reaction byproducts such as methanol (CH3OH), formaldehyde (H2CO) and also simpler hydrocarbons as methyl acetylene (CH3CCH). Under an Astrobiology perspective it is plausible to map PAHs and oxygen compounds

  16. Pt(II) and Pd(II) complexes with ibuprofen hydrazide: Characterization, theoretical calculations, antibacterial and antitumor assays and studies of interaction with CT-DNA

    Science.gov (United States)

    Manzano, Carlos M.; Bergamini, Fernando R. G.; Lustri, Wilton R.; Ruiz, Ana Lúcia T. G.; de Oliveira, Ellen C. S.; Ribeiro, Marcos A.; Formiga, André L. B.; Corbi, Pedro P.

    2018-02-01

    Palladium(II) and platinum(II) complexes with a hydrazide derivative of ibuprofen (named HIB) were synthesized and characterized by chemical and spectroscopic methods. Elemental and thermogravimetric analyses, as well as ESI-QTOF-MS studies for both complexes, confirmed a 1:2:2 metal/HIB/Cl- molar ratio. The crystal structure of the palladium(II) complex was solved by single crystal X-ray diffractometric analysis, which permitted identifying the coordination formula [PdCl2(HIB)2]. Crystallographic studies also indicate coordination of HIB to the metal by the NH2 group. Nuclear magnetic resonance and infrared spectroscopies reinforced the coordination observed in the crystal structure and suggested that the platinum(II) complex presents similar coordination modes and structure when compared with the Pd(II) complex. The complexes had their structures optimized with the aid of DFT methods. In vitro antiproliferative assays showed that the [PdCl2(HIB)2] complex is active over ovarian cancer cell line OVCAR-03, while biophysical studies indicated its capacity to interact with CT-DNA. The complexes were inactive over Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa bacterial strains.

  17. Cellular interactions of a water-soluble supramolecular polymer complex of carbon nanotubes with human epithelial colorectal adenocarcinoma cells.

    Science.gov (United States)

    Lee, Yeonju; Geckeler, Kurt E

    2012-08-01

    Water-soluble, PAX-loaded carbon nanotubes are fabricated by employing a synthetic polyampholyte, PDM. To investigate the suitability of the polyampholyte and the nanotubes as drug carriers, different cellular interactions such as the human epithelial Caco-2 cells viability, their effect on the cell growth, and the change in the transepithelial electrical resistance in Caco-2 cells are studied. The resulting complex is found to exhibit an effective anti-cancer effect against colon cancer cells and an increased the reduction of the electrical resistance in the Caco-2 cells when compared to the precursor PAX. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Radiolytic and photochemical reduction of carbon dioxide in solution catalyzed by transition metal complexes with some selected macrocycles

    International Nuclear Information System (INIS)

    Grodkowski, J.

    2004-01-01

    The main goal of the work presented in this report is an explanation of the mechanism of carbon dioxide (CO 2 ) reduction catalyzed by transition metal complexes with some selected macrocycles. The catalytic function of two electron exchange centers in the reduction of CO 2 , an inner metal and a macrocycle ring, was defined. Catalytic effects of rhodium, iron and cobalt porphyrins, cobalt and iron phthalocyanines and corroles as well as cobalt corrins have been investigated. CO 2 reduction by iron ions without presence of macrocycles and also in presence of copper compounds in aqueous solutions have been studied as well

  19. Catalysis with Gold Complexes Immobilised on Carbon Nanotubes by π-π Stacking Interactions: Heterogeneous Catalysis versus the Boomerang Effect.

    Science.gov (United States)

    Vriamont, Charles; Devillers, Michel; Riant, Olivier; Hermans, Sophie

    2013-09-02

    A new pyrene-tagged gold(I) complex has been synthesised and tested as a homogeneous catalyst. First, a simple 1,6-enyne was chosen as a model substrate for cyclisation by using different solvents to optimise the reaction conditions. The non-covalent immobilisation of our pyrene-tagged gold complex onto multi-walled carbon nanotubes through π-π stacking interactions was then explored to obtain a supported homogeneous catalyst. The heterogenised catalyst and its homogeneous counterpart exhibited similar activity in a range of enyne cyclisation reactions. Bearing in mind that π-π interactions are affected by temperature and solvent polarity, the reuse and robustness of the supported homogeneous catalyst was tested to explore the scope and limitations of the recyclability of this catalyst. Under the optimised conditions, recyclability was observed by using the concept of the boomerang effect. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Transition Metal Complexes Coordinated by Water Soluble Phosphane Ligands: How Cyclodextrins Can Alter the Coordination Sphere?

    Directory of Open Access Journals (Sweden)

    Michel Ferreira

    2017-01-01

    Full Text Available The behaviour of platinum(II and palladium(0 complexes coordinated by various hydrosoluble monodentate phosphane ligands has been investigated by 31P{1H} NMR spectroscopy in the presence of randomly methylated β-cyclodextrin (RAME-β-CD. This molecular receptor can have no impact on the organometallic complexes, induce the formation of phosphane low-coordinated complexes or form coordination second sphere species. These three behaviours are under thermodynamic control and are governed not only by the affinity of RAME-β-CD for the phosphane but also by the phosphane stereoelectronic properties. When observed, the low-coordinated complexes may be formed either via a preliminary decoordination of the phosphane followed by a complexation of the free ligand by the CD or via the generation of organometallic species complexed by CD which then lead to expulsion of ligands to decrease their internal steric hindrance.

  1. Porous structured niobium pentoxide/carbon complex for lithium-ion intercalation pseudocapacitors

    International Nuclear Information System (INIS)

    Luo, Guoming; Li, Heshun; Gao, Lixin; Zhang, Daquan; Lin, Tong

    2016-01-01

    Highlights: • A simple one-pot in situ hydrothermal method to prepare T-Nb_2O_5/C. • The composite has well-dispersed C among nano-scale Nb_2O_5. • The composite has excellent large-current discharge property. • The composite has no obvious drop after 1000 cycles at 5 A g"−"1. - Abstract: A facile soft-templated synthesis of the niobium pentoxide/carbon (Nb_2O_5/C) from the polymerization of resorcinol with formaldehyde under the hydrothermal condition is introduced. This material has been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS) techniques. The carbon is well-dispersed in the nanostructure along with Nb_2O_5 and the material is porous. The intimate contact between Nb_2O_5 and carbon improves its conductivity. The electrochemical studies revealed that the porous Nb_2O_5/C displayed good pseudocapacitive response. The specific capacitance of the Nb_2O_5/C was 387 F g"−"1 at 0.1 A g"−"1 and 210 F g"−"1 at 5 A g"−"1. The Nb_2O_5/C exhibits superior cycling performance, which can remain about 96% of its initial capacitance after 1000 cycles at 5 A g"−"1.

  2. Carbon-Based Oxamate Cobalt(III) Complexes as Bioenzyme Mimics for Contaminant Elimination in High Backgrounds of Complicated Constituents.

    Science.gov (United States)

    Li, Nan; Zheng, Yun; Jiang, Xuemei; Zhang, Ran; Pei, Kemei; Chen, Wenxing

    2017-10-12

    Complex wastewater with massive components is now a serious environmental issue facing humanity. Selective removal of low-concentration contaminants in mixed constituents holds great promise for increasing water supplies. Bioenzymes like horseradish peroxidase exhibit oxidizing power and selectivity. Here, we manufactured its mimic through immobilizing non-heme oxamate anionic cobalt(III) complex ([Co III (opba)] - , opba = o-phenylenebis(oxamate)) onto pyridine (Py) modified multiwalled carbon nanotubes ([Co III (opba)] - -Py-MWCNTs, MWCNTs = multiwalled carbon nanotubes), where MWCNTs captured substrates and Py functioned as the fifth ligand. We chose typical azo dye (C.I. Acid Red 1) and antibiotic (ciprofloxacin) as model substrates. Without •OH, this catalyst could detoxify target micropollutants efficiently at pH from 8 to 11. It also remained efficient in repetitive tests, and the final products were non-poisonous OH-containing acids. Combined with radical scavenger tests and electron paramagnetic resonance result, we speculated that high-valent cobalt-oxo active species and oxygen atom transfer reaction dominated in the reaction pathway. According to density functional theory calculations, the electron spin density distribution order showed that electron-withdrawing ligand was beneficial for inward pulling the excess electron and lowering the corresponding energy levels, achieving an electrophilic-attack enhancement of the catalyst. With target removal property and recyclability, this catalyst is prospective in water detoxication.

  3. Cobalt(III) complexes of [3(5)]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane. Report of an inert, chelate hydrogen carbonate ion

    DEFF Research Database (Denmark)

    Broge, Louise; Søtofte, Inger; Olsen, Carl Erik

    2001-01-01

    .H2O (3a). The coordination geometry around the cobalt(III) ion is a distorted octahedron with the inorganic ligands at cis-positions. Complex 2 is the second example of a cobalt(III) complex for which the X-ray structure,sfiows a chelate binding mode of the hydrogen carbonate entity. The pK(a) value...

  4. Thermodynamical, kinetic and structural properties of simple and mixed complexes of zirconium (IV) with the hydroxyl and carbonate ions. Study by potentiometry, Raman spectroscopy and NMR spectroscopy

    International Nuclear Information System (INIS)

    Veyland, A.

    1999-01-01

    Most of zirconium production is used by the nuclear industry for the cladding of nuclear fuels and for the storage of radioactive wastes. The aim of this work is the qualitative and quantitative study of the complexes made by zirconium with the hydroxyl and carbonate ions in order to evaluate the long-term pollution risks linked with the corrosion of confinement containers. The zirconium(IV)/hydroxyl system is studied by proto-metry and follows a protocol which reduces the local over-concentrations of reagent and the precipitation of zirconium hydroxide. In potassium nitrate environment and in a pH range of 1.5 to 3.5, three soluble species are evidenced: Zr(OH) 3 + , Zr 2 (OH) 7 + and Zr(OH) 4 . Their apparent constant of formation and the solubility product of zirconium hydroxide are determined with 4 ionic forces. Using these results, the corresponding thermodynamic constants are calculated by applying the theory of specific interactions. The formation of zirconium (IV) hydroxo-carbonate complexes is evidenced by proto-metry and 17 O and 13 C NMR. The number of carbonates fixed by zirconium varies from 0 to 4. The dialysis indicates that the degree of poly-condensation of species is an inverse function of the number of complex carbonates. The Raman polarized spectra and the 13 C NMR results demonstrate for all complexes the bidentate character of the complexation mode of the carbonates. The dynamical study made by 13 C NMR of the exchange between complexed carbonates of the tetra-carbonate-zirconate ion and free carbonates in solution allows to determine the kinetic constants and the corresponding velocity law. An associative mechanism is proposed, in agreement with the results obtained by mass spectroscopy with electro-spray ionization. These new thermodynamical and kinetic data allow to model the speciation of zirconium in natural waters. (J.S.)

  5. Adsorption of lead(II) and copper(II) on activated carbon by complexation with surface functional groups

    International Nuclear Information System (INIS)

    Pesavento, Maria; Profumo, Antonella; Alberti, Giancarla; Conti, Fabio

    2003-01-01

    The adsorption of lead(II) and copper(II) on an activated carbon (Filtrasorb 300, Chemviron) was characterized assuming that it takes place by formation of complexes with functional groups, present in the activated carbon. Their concentration and conditional adsorption coefficients were determined for each metal by titration of the carbon in suspension in aqueous phase, at constant acidity, with the metal itself. For each titration point, the concentration of the metal in the solution phase after equilibration was determined, and the data were processed by the Ruzic linearization method, to obtain the concentration of the active sites involved in the sorption, and the conditional constant. The effect of the pH was also examined, in the range 4-6, obtaining that the adsorption increases at increasing pH. The protonation and adsorption constants were determined from the conditional adsorption coefficients obtained at the different acidities. The concentration of the active sites is 0.023 and 0.042 mmol g -1 , and the protonation constants are 1.0x10 6 and 4.6x10 4 M -1 for Pb(II) and Cu(II). The corresponding adsorption constants are respectively 1.4x10 5 and 6.3x10 3 M -1 . All the parameters are affected by a large uncertainty, probably due to the heterogeneity of the active groups in the activated carbon. Even if so, these parameters make it possible a good prediction of the adsorption in a wide range of conditions. Other sorption mechanism can be set up at different conditions, in particular at different pH, as it has been demonstrated in the case of copper(II)

  6. Adsorption of lead(II) and copper(II) on activated carbon by complexation with surface functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Pesavento, Maria; Profumo, Antonella; Alberti, Giancarla; Conti, Fabio

    2003-03-17

    The adsorption of lead(II) and copper(II) on an activated carbon (Filtrasorb 300, Chemviron) was characterized assuming that it takes place by formation of complexes with functional groups, present in the activated carbon. Their concentration and conditional adsorption coefficients were determined for each metal by titration of the carbon in suspension in aqueous phase, at constant acidity, with the metal itself. For each titration point, the concentration of the metal in the solution phase after equilibration was determined, and the data were processed by the Ruzic linearization method, to obtain the concentration of the active sites involved in the sorption, and the conditional constant. The effect of the pH was also examined, in the range 4-6, obtaining that the adsorption increases at increasing pH. The protonation and adsorption constants were determined from the conditional adsorption coefficients obtained at the different acidities. The concentration of the active sites is 0.023 and 0.042 mmol g{sup -1}, and the protonation constants are 1.0x10{sup 6} and 4.6x10{sup 4} M{sup -1} for Pb(II) and Cu(II). The corresponding adsorption constants are respectively 1.4x10{sup 5} and 6.3x10{sup 3} M{sup -1}. All the parameters are affected by a large uncertainty, probably due to the heterogeneity of the active groups in the activated carbon. Even if so, these parameters make it possible a good prediction of the adsorption in a wide range of conditions. Other sorption mechanism can be set up at different conditions, in particular at different pH, as it has been demonstrated in the case of copper(II)

  7. Carbon dioxide is tightly bound in the [Co(Pyridine)(CO2)](-) anionic complex.

    Science.gov (United States)

    Graham, Jacob D; Buytendyk, Allyson M; Zhang, Xinxing; Kim, Seong K; Bowen, Kit H

    2015-11-14

    The [Co(Pyridine)(CO2)](-) anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO2 binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO2)](-) in which a central cobalt atom is bound to pyridine and CO2 moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO2 to be bound within the anionic complex by 1.4 eV.

  8. Carbon dioxide is tightly bound in the [Co(Pyridine)(CO2)]- anionic complex

    Science.gov (United States)

    Graham, Jacob D.; Buytendyk, Allyson M.; Zhang, Xinxing; Kim, Seong K.; Bowen, Kit H.

    2015-11-01

    The [Co(Pyridine)(CO2)]- anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO2 binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO2)]- in which a central cobalt atom is bound to pyridine and CO2 moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO2 to be bound within the anionic complex by 1.4 eV.

  9. Porous structured niobium pentoxide/carbon complex for lithium-ion intercalation pseudocapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Guoming; Li, Heshun; Gao, Lixin [School of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Zhang, Daquan, E-mail: zhangdaquan@shiep.edu.cn [School of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Lin, Tong [Institute for Frontier Materials, Deakin University, Geelong, VIC 3216 (Australia)

    2016-12-15

    Highlights: • A simple one-pot in situ hydrothermal method to prepare T-Nb{sub 2}O{sub 5}/C. • The composite has well-dispersed C among nano-scale Nb{sub 2}O{sub 5}. • The composite has excellent large-current discharge property. • The composite has no obvious drop after 1000 cycles at 5 A g{sup −1}. - Abstract: A facile soft-templated synthesis of the niobium pentoxide/carbon (Nb{sub 2}O{sub 5}/C) from the polymerization of resorcinol with formaldehyde under the hydrothermal condition is introduced. This material has been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS) techniques. The carbon is well-dispersed in the nanostructure along with Nb{sub 2}O{sub 5} and the material is porous. The intimate contact between Nb{sub 2}O{sub 5} and carbon improves its conductivity. The electrochemical studies revealed that the porous Nb{sub 2}O{sub 5}/C displayed good pseudocapacitive response. The specific capacitance of the Nb{sub 2}O{sub 5}/C was 387 F g{sup −1} at 0.1 A g{sup −1} and 210 F g{sup −1} at 5 A g{sup −1}. The Nb{sub 2}O{sub 5}/C exhibits superior cycling performance, which can remain about 96% of its initial capacitance after 1000 cycles at 5 A g{sup −1}.

  10. Conduction properties of thin films from a water soluble carbon nanotube/hemicellulose complex

    Science.gov (United States)

    Shao, Dongkai; Yotprayoonsak, Peerapong; Saunajoki, Ville; Ahlskog, Markus; Virtanen, Jorma; Kangas, Veijo; Volodin, Alexander; Van Haesendonck, Chris; Burdanova, Maria; Mosley, Connor D. W.; Lloyd-Hughes, James

    2018-04-01

    We have examined the conductive properties of carbon nanotube based thin films, which were prepared via dispersion in water by non-covalent functionalization of the nanotubes with xylan, a type of hemicellulose. Measurements of low temperature conductivity, Kelvin probe force microscopy, and high frequency (THz) conductivity elucidated the intra-tube and inter-tube charge transport processes in this material. The measurements show excellent conductive properties of the as prepared thin films, with bulk conductivity up to 2000 S cm-1. The transport results demonstrate that the hemicellulose does not seriously interfere with the inter-tube conductance.

  11. The impact of economic complexity on carbon emissions: evidence from France.

    Science.gov (United States)

    Can, Muhlis; Gozgor, Giray

    2017-07-01

    This paper reanalyzes the determinants of the CO 2 emissions in France. For this purpose, it considers the unit root test with two structural breaks and a dynamic ordinary least squares estimation. The paper also considers the effects of the energy consumption and the economic complexity on CO 2 emissions. First, it is observed that the EKC hypothesis is valid in France. Second, the positive effect of the energy consumption on CO 2 emissions is obtained. Third, it is observed that a higher economic complexity suppresses the level of CO 2 emissions in the long run. The findings imply noteworthy environmental policy implications to decrease the level of CO 2 emissions in France.

  12. Designing tough and fracture resistant polypropylene/multi wall carbon nanotubes nanocomposites by controlling stereo-complexity and dispersion morphology

    International Nuclear Information System (INIS)

    Das, Dibyendu; Satapathy, Bhabani K.

    2014-01-01

    Highlights: • New pathway to improve dispersion and toughness by tacticity modification. • >330% toughness enhancement in PP/MWCNT nanocomposites with stereo-complex PP. • Prominent dispersion and distribution morphology due to matrix stereocomplexity. • Tacticity induced “Semi-ductile-to-tough-to-quasi-brittle” transitions in the PP/MWCNT. • Two-fold reduced steady state CTOD rate in i-PP+s-PP/ MWCNT nanocomposites. - Abstract: A remarkable toughness enhancement (>330%) of multi wall carbon nanotubes (MWCNT) filled stereo-complex polypropylene (PP) matrix i.e. blend of isotactic-PP and syndiotactic-PP (70:30) with differences in stereo-regularity has been observed. The enhancement has been correlated to quantifiable morphological parameters such as free-space lengths concerning dispersion and relatively greater reduction in crystallite size/lamellar thickness. Systematic analysis of glass transition data and estimation of multi wall carbon nanotubes induced reduction in interfacial polymer chain immobilization reiterates susceptibility of polymer segments to ready-mobility. The extent of toughening has quantitatively been analyzed by fracture-energy partitioning, essential work of fracture (EWF), approach enabling the detection of a “semi-ductile-to-tough-to-quasi-brittle” transition in the MWCNT filled stereo-complex polypropylene. Real-time fracture kinetics analysis revealed toughening mechanism to be primarily blunting-assisted; an aspect also corroborated by extensive plastic flow without much energy dissipation in the inner fracture process zone. Thus the study establishes a new pathway of tacticity-defined matrix modification to toughen nanocomposites

  13. Peculiarities of extraction of carbonate complexes of trivalent transplutonium elements by alkylpyrocatechins

    International Nuclear Information System (INIS)

    Karalova, Z.K.; Bukina, T.I.; Myasoedov, B.F.; Fedorov, L.A.; Sokolovskij, S.A.

    1987-01-01

    Extraction of trivalent americium, curium, californium and europium by technical mixture of mono- and didecylpyrocatechin (TAP) in various diluents from carbonate solutions is investigated. Effect of many factors (pH, K 2 CO 3 concentration, TAP, metal; the time of phase contact) on the completeness of element isolation and separation is clarified. It is ascertained that the elements listed are quantitatively extracted by TAP solution in toluene and cyclohexane in the range of K 2 CO 3 concentrations from 0.25 to 1.5 mol/l. The difference in americium and curium distribution coefficient during their extraction by TAP from 0.25 mol/l of K 2 CO 3 solution is detected. Separation coefficients of the pair increase with the increase of carbonate solution pH. The separation can be improved at the stage of element reextraction by the mixture of K 2 CO 3 and DTPA or EDTA from alkylpyrocatechin, sunce rate constants of americium and curium reextraction differ greatly. Using 13 C NMR the composition of compounds in organic phase on the basis of 4-(α, α-dioctylethyl)pyrocatechin is investigated

  14. Complex forest dynamics indicate potential for slowing carbon accumulation in the southeastern United States.

    Science.gov (United States)

    Coulston, John W; Wear, David N; Vose, James M

    2015-01-23

    Over the past century forest regrowth in Europe and North America expanded forest carbon (C) sinks and offset C emissions but future C accumulation is uncertain. Policy makers need insights into forest C dynamics as they anticipate emissions futures and goals. We used land use and forest inventory data to estimate how forest C dynamics have changed in the southeastern United States and attribute changes to land use, management, and disturbance causes. From 2007-2012, forests yielded a net sink of C because of net land use change (+6.48 Tg C yr(-1)) and net biomass accumulation (+75.4 Tg C yr(-1)). Forests disturbed by weather, insect/disease, and fire show dampened yet positive forest C changes (+1.56, +1.4, +5.48 Tg C yr(-1), respectively). Forest cutting caused net decreases in C (-76.7 Tg C yr(-1)) but was offset by forest growth (+143.77 Tg C yr(-1)). Forest growth rates depend on age or stage of development and projected C stock changes indicate a gradual slowing of carbon accumulation with anticipated forest aging (a reduction of 9.5% over the next five years). Additionally, small shifts in land use transitions consistent with economic futures resulted in a 40.6% decrease in C accumulation.

  15. Erosion and sedimentation effects on soil : organic carbon redistribution in a complex landscape of western Ecuador

    NARCIS (Netherlands)

    Corre, M.D.; Schoorl, J.M.; Koning, de F.; López-Ulloa, M.; Veldkamp, E.

    2015-01-01

    This study was conducted to evaluate how land-use changes affect the distribution of SOC within a complex tropical landscape through the processes of erosion and sedimentation. The objectives were: (i) to estimate the present SOC storage at a landscape scale using predictors such as slope,

  16. Simultaneous quantification of dissolved organic carbon fractions and copper complexation using solid-phase extraction

    International Nuclear Information System (INIS)

    McElmurry, Shawn P.; Long, David T.; Voice, Thomas C.

    2010-01-01

    Trace metal cycling in natural waters is highly influenced by the amount and type of dissolved organic C (DOC). Although determining individual species of DOC is unrealistic, there has been success in classifying DOC by determining operationally defined fractions. However, current fractionation schemes do not allow for the simultaneous quantification of associated trace metals. Using operational classifications, a scheme was developed to fractionate DOC based on a set of seven solid-phase extraction (SPE) cartridges. The cartridges isolated fractions based on a range of specific mechanisms thought to be responsible for DOC aggregation in solution, as well as molecular weight. The method was evaluated to determine if it can identify differences in DOC characteristics, including differences in Cu-DOC complexation. Results are that: (1) cartridge blanks were low for both DOC and Cu, (2) differences are observed in the distribution of DOC amongst the fractions from various sources that are consistent with what is known about the DOC materials and the mechanisms operative for each cartridge, (3) when present as a free cation, Cu was not retained by non-cationic cartridges allowing the method to be used to assess Cu binding, (4) the capability of the method to provide quantitative assessment of Cu-DOC complexation was demonstrated for a variety of DOC standards, (5) Cu was found to preferentially bind with high molecular weight fractions of DOC, and (6) estimated partitioning coefficients and conditional binding constants for Cu were similar to those reported elsewhere. The method developed describes DOC characteristics based on specific bonding mechanisms (hydrogen, donor-acceptor, London dispersion, and ionic bonding) while simultaneously quantifying Cu-DOC complexation. The method provides researchers a means of describing not only the extent of DOC complexation but also how that complex will be behave in natural waters.

  17. Age-related patterns of forest complexity and carbon storage in pine and aspen-birch ecosystems of northern Minnesota, USA

    International Nuclear Information System (INIS)

    Bradford, J.B.; Kastendick, D.N.

    2010-01-01

    Forest managers are now developing strategies to mitigate increases in atmospheric carbon dioxide (CO 2 ) and help stands to adapt to new climatic conditions. This study characterized the influence of stand age on carbon storage and sequestration in chronosequences of even-aged red pine and aspen-birch stands in northern Minnesota. The aim of the study was to determine the impact of age-related management strategies on carbon storage and forest complexity. The pine chronosequences ranged from 7 to 160 years. Aspen chronosequences ranged from 6 to 133 years. Field measurements of the trees were compiled into 5 carbon pools. Carbon storage variables were averaged within each stand in order to conduct a regression analysis. The study showed that forest complexity was positively related to stand age in all of the measured response variables except species richness. Relationships between compositional complexity and stand age depended on forest type. Total carbon storage also increased with age. Results of the study showed that age plays an important role in overall ecosystem carbon storage. The study can be used to provide insights into the overall costs and benefits of forest management strategies that favour younger or older forests. 45 refs., 2 figs.

  18. Enhancing Carbon Fixation by Metabolic Engineering: A Model System of Complex Network Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Stephanopoulos

    2008-04-10

    In the first two years of this research we focused on the development of a DNA microarray for transcriptional studies in the photosynthetic organism Synechocystis and the elucidation of the metabolic pathway for biopolymer synthesis in this organism. In addition we also advanced the molecular biological tools for metabolic engineering of biopolymer synthesis in Synechocystis and initiated a series of physiological studies for the elucidation of the carbon fixing pathways and basic central carbon metabolism of these organisms. During the last two-year period we focused our attention on the continuation and completion of the last task, namely, the development of tools for basic investigations of the physiology of these cells through, primarily, the determination of their metabolic fluxes. The reason for this decision lies in the importance of fluxes as key indicators of physiology and the high level of information content they carry in terms of identifying rate limiting steps in a metabolic pathway. While flux determination is a well-advanced subject for heterotrophic organisms, for the case of autotrophic bacteria, like Synechocystis, some special challenges had to be overcome. These challenges stem mostly from the fact that if one uses {sup 13}C labeled CO{sub 2} for flux determination, the {sup 13}C label will mark, at steady state, all carbon atoms of all cellular metabolites, thus eliminating the necessary differentiation required for flux determination. This peculiarity of autotrophic organisms makes it imperative to carry out flux determination under transient conditions, something that had not been accomplished before. We are pleased to report that we have solved this problem and we are now able to determine fluxes in photosynthetic organisms from stable isotope labeling experiments followed by measurements of label enrichment in cellular metabolites using Gas Chromatography-Mass Spectrometry. We have conducted extensive simulations to test the method and

  19. Preparation of Pt Nanocatalyst on Carbon Materials via a Reduction Reaction of a Pt Precursor in a Drying Process.

    Science.gov (United States)

    Lee, Jae-Young; Lee, Woo-Kum; Rim, Hyung-Ryul; Joung, Gyu-Bum; Weidner, John W; Lee, Hong-Ki

    2016-06-01

    Platinum (Pt) nanocatalyst for a proton-exchange membrane fuel cell (PEMFC) was prepared on a carbon black particle or a graphite particle coated with a nafion polymer via a reduction of platinum(II) bis(acetylacetonate) denoted as Pt(acac)2 as a Pt precursor in a drying process. Sublimed Pt(acac)2 adsorbed on the nafion-coated carbon materials was reduced to Pt nanoparticles in a glass reactor at 180 degrees C of N2 atmosphere. The morphology of Pt nanoparticles on carbon materials was observed by scanning electron microscopy (SEM) and the distribution of Pt nanoparticles was done by transmission electron microscopy (TEM). The particle size was estimated by analyzing the TEM image using an image analyzer. It was found that nano-sized Pt particles were deposited on the surface of carbon materials, and the number density and the average particle size increased with increasing reduction time.

  20. PEGylated anticancer-carbon nanotubes complex targeting mitochondria of lung cancer cells

    Science.gov (United States)

    Kim, Sang-Woo; Lee, Yeon Kyung; Lee, Jong Yeon; Hong, Jeong Hee; Khang, Dongwoo

    2017-11-01

    Although activating apoptosis in cancer cells by targeting the mitochondria is an effective strategy for cancer therapy, insufficient targeting of the mitochondria in cancer cells restricts the availability in clinical treatment. Here, we report on a polyethylene glycol-coated carbon nanotube (CNT)-ABT737 nanodrug that improves the mitochondrial targeting of lung cancer cells. The polyethylene glycol-coated CNT-ABT737 nanodrug internalized into the early endosomes via macropinocytosis and clathrin-mediated endocytosis in advance of early endosomal escape and delivered into the mitochondria. Cytosol release of the nanodrug led to apoptosis of lung cancer cells by abruption of the mitochondrial membrane potential, inducing Bcl-2-mediated apoptosis and generating intracellular reactive oxygen species. As such, this study provides an effective strategy for increasing the anti-lung cancer efficacy by increasing mitochondria accumulation rate of cytosol released anticancer nanodrugs.

  1. Iron(III) diethylenetriaminepentaacetic acid complex on polyallylamine functionalized multiwalled carbon nanotubes: immobilization, direct electrochemistry and electrocatalysis.

    Science.gov (United States)

    Liu, Hailing; Cui, Yanyun; Li, Pan; Zhou, Yiming; Zhu, Xiaoshu; Tang, Yawen; Chen, Yu; Lu, Tianhong

    2013-05-07

    A nonenzymatic iron(III) diethylenetriaminepentaacetic acid (Fe(III)-DETPA) complex based amperometric sensor for the analytical determination of hydrogen peroxide was developed. By combining the electrostatic interaction between the Fe(III)-DETPA complex and polyallylamine (PAH) functionalized multiwalled carbon nanotubes (MWCNTs) as well as the ionotropic crosslinking interaction between PAH and ethylenediamine-tetramethylene phosphonic acid (EDTMP), the electroactive Fe(III)-DETPA complex was successfully incorporated within the MWCNT matrix, and firmly immobilized on the Au substrate electrode. The fabricated electrochemical sensor was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical methods. The influences of solution pH and ionic strength on the electrochemical sensor were investigated. The prepared electrochemical sensor had a fast response to hydrogen peroxide (<3 s) and an excellent linear range of concentration from 1.25 × 10(-8) to 4.75 × 10(-3) M with a detection limit of 6.3 × 10(-9) M under the optimum conditions.

  2. Chemistry of Carbon Monoxide Free Cyclopentadienylvanadium(I) Alkene and Alkyne Complexes

    NARCIS (Netherlands)

    Hessen, Bart; Meetsma, Auke; Bolhuis, Fré van; Teuben, Jan H.; Helgesson, Göran; Jagner, Susan

    The compounds CpV(L)(PMe3)2 (L = η2-ethene (2), η2-alkyne) form a new class of highly reactive CO-free CpVI complexes. Paramagnetic 2 was prepared from CpVCl(PMe3)2 and 0.5 mol of BrMg(CH2)4MgBr. An X-ray structure determination shows a relatively short ethene C=C distance of 1.365 (5) Å. The

  3. Reductive Coupling of Carbon Monoxide in a Rhenium Carbonyl Complex with Pendant Lewis Acids

    OpenAIRE

    Miller, Alexander J. M.; Labinger, Jay A.; Bercaw, John E.

    2008-01-01

    Phosphinoborane ligands impart unique reactivity to a rhenium carbonyl cation relative to simple phosphine complexes. Addition of either triethylborohydride or a platinum hydride (that can be formed from H2) forms a rhenium boroxycarbene. This carbene, which crystallizes as a dimer, disproportionates over a period of days to afford the starting cation and a structurally unprecedented boroxy(boroxymethyl)carbene, in which a new C−C bond has been formed between two reduced CO ligands. This prod...

  4. End-labeling of peptide nucleic acid with osmium complex. Voltammetry at carbon and mercury electrodes

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Trefulka, Mojmír; Fojta, Miroslav

    2009-01-01

    Roč. 11, č. 2 (2009), s. 359-362 ISSN 1388-2481 R&D Projects: GA AV ČR(CZ) KAN400310651; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : peptide nucleic acid end-labeling * osmium tetroxide complexes * electroactive labels Subject RIV: BO - Biophysics Impact factor: 4.243, year: 2009

  5. Radiation accelerated formation of oxygen and carbon related complexes in silicon

    International Nuclear Information System (INIS)

    Lazrak, A.; Magnea, N.; Pautrat, J.L.

    1984-06-01

    During the pulling of silicon monocrystals by the Czochralsky method, oxygen is incorporated into the lattice. It is known from early works that low temperature annealings (400-1000 0 C) make this oxygen to precipitate and a number of different defects to be generated. In order to check whether the fast diffusivity of an oxygen silicon interstitial complex has to be taken in consideration it was interesting to examinate the possible role of radiation damage on the formation of oxygen related defects. Experimental results of an experiment are presented and discussed

  6. Reductive coupling of carbon monoxide in a rhenium carbonyl complex with pendant Lewis acids.

    Science.gov (United States)

    Miller, Alexander J M; Labinger, Jay A; Bercaw, John E

    2008-09-10

    Phosphinoborane ligands impart unique reactivity to a rhenium carbonyl cation relative to simple phosphine complexes. Addition of either triethylborohydride or a platinum hydride (that can be formed from H2) forms a rhenium boroxycarbene. This carbene, which crystallizes as a dimer, disproportionates over a period of days to afford the starting cation and a structurally unprecedented boroxy(boroxymethyl)carbene, in which a new C-C bond has been formed between two reduced CO ligands. This product of C-C bond formation can be independently synthesized by addition of 2 equiv of hydride to the rhenium carbonyl cation.

  7. Effects of cryoprotectants on the structure and thermostability of the human carbonic anhydrase II–acetazolamide complex

    International Nuclear Information System (INIS)

    Aggarwal, Mayank; Boone, Christopher D.; Kondeti, Bhargav; Tu, Chingkuang; Silverman, David N.; McKenna, Robert

    2013-01-01

    Here, a case study of the effects of cryoprotectants on the kinetics of carbonic anhydrase II (CA II) and its inhibition by the clinically used inhibitor acetazolamide (AZM) is presented. Protein X-ray crystallography has seen a progressive shift from data collection at cool/room temperature (277–298 K) to data collection at cryotemperature (100 K) because of its ease of crystal preparation and the lessening of the detrimental effects of radiation-induced crystal damage, with 20–25%(v/v) glycerol (GOL) being the preferred choice of cryoprotectant. Here, a case study of the effects of cryoprotectants on the kinetics of carbonic anhydrase II (CA II) and its inhibition by the clinically used inhibitor acetazolamide (AZM) is presented. Comparative studies of crystal structure, kinetics, inhibition and thermostability were performed on CA II and its complex with AZM in the presence of either GOL or sucrose. These results suggest that even though the cryoprotectant GOL was previously shown to be directly bound in the active site and to interact with AZM, it affects neither the thermostability of CA II nor the binding of AZM in the crystal structure or in solution. However, addition of GOL does affect the kinetics of CA II, presumably as it displaces the water proton-transfer network in the active site

  8. Effects of cryoprotectants on the structure and thermostability of the human carbonic anhydrase II–acetazolamide complex

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Mayank; Boone, Christopher D.; Kondeti, Bhargav; Tu, Chingkuang; Silverman, David N.; McKenna, Robert, E-mail: rmckenna@ufl.edu [University of Florida, 1600 SW Archer Road, PO Box 100245, Gainesville, FL 32610 (United States)

    2013-05-01

    Here, a case study of the effects of cryoprotectants on the kinetics of carbonic anhydrase II (CA II) and its inhibition by the clinically used inhibitor acetazolamide (AZM) is presented. Protein X-ray crystallography has seen a progressive shift from data collection at cool/room temperature (277–298 K) to data collection at cryotemperature (100 K) because of its ease of crystal preparation and the lessening of the detrimental effects of radiation-induced crystal damage, with 20–25%(v/v) glycerol (GOL) being the preferred choice of cryoprotectant. Here, a case study of the effects of cryoprotectants on the kinetics of carbonic anhydrase II (CA II) and its inhibition by the clinically used inhibitor acetazolamide (AZM) is presented. Comparative studies of crystal structure, kinetics, inhibition and thermostability were performed on CA II and its complex with AZM in the presence of either GOL or sucrose. These results suggest that even though the cryoprotectant GOL was previously shown to be directly bound in the active site and to interact with AZM, it affects neither the thermostability of CA II nor the binding of AZM in the crystal structure or in solution. However, addition of GOL does affect the kinetics of CA II, presumably as it displaces the water proton-transfer network in the active site.

  9. A highly efficient nano-cluster artificial peroxidase and its direct electrochemistry on a nano complex modified glassy carbon electrode.

    Science.gov (United States)

    Hong, Jun; Wang, Wei; Huang, Kun; Yang, Wei-Yun; Zhao, Ying-Xue; Xiao, Bao-Lin; Gao, Yun-Fei; Moosavi-Movahedi, Zainab; Ghourchian, Hedayatollah; Moosavi-Movahedi, Ali Akbar

    2012-01-01

    A nano-cluster with highly efficient peroxide activity was constructed based on nafion (NF) and cytochrome c (Cyt c). UV-Vis spectrometry and transmission electron microscopy (TEM) methods were utilized for characterization of the nano-structured enzyme or artificial peroxidase (AP). The nano-cluster was composed of a Chain-Ball structure, with an average ball size of about 40 nm. The Michaelis-Menten (K(m)) and catalytic rate (k(cat)) constants of the AP were determined to be 2.5 ± 0.4 µM and 0.069 ± 0.001 s(-1), respectively, in 50 mM PBS at pH 7.0. The catalytic efficiency of the AP was evaluated to be 0.028 ± 0.005 µM(-1) s(-1), which was 39 ± 5% as efficient as the native horseradish peroxidase (HRP). The AP was also immobilized on a functional multi-wall carbon nanotube (MWNCTs)-gold colloid nanoparticles (AuNPs) nano-complex modified glassy carbon (GC) electrode. The cyclic voltammetry of AP on the nano complex modified GC electrode showed a pair of well-defined redox peaks with a formal potential (E°') of -45 ± 2 mV (vs. Ag/AgCl) at a scan rate of 0.05 V/s. The heterogeneous electron transfer rate constant (k(s)) was evaluated to be 0.65 s(-1). The surface concentration of electroactive AP on GC electrode (Γ) was 7 × 10(-10) mol cm(-2). The apparent Michaelis-Menten constant (K(m)(app)) was 0.23 nM.

  10. Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes.

    Science.gov (United States)

    Henao-Holguín, Laura Verónica; Basiuk, Vladimir A

    2015-06-01

    Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations. For reasons of comparison, we employed three such functionals: M06-2X and LC-BLYP as implemented in Gaussian 09 package, and PBE-G as implemented in Materials Studio 6.0. In order to roughly estimate the effect of nanotube chirality on the interaction strenght, we considered two short closed-end SWNT models (also referred to as 'elongated fullerenes'), one armchair and one zigzag, derived from C60 and C80 hemispheres. In addition, we calculated similar complexes with C60, as well as I h and D 5h isomers of C80. The results were analyzed in terms of optimized geometries, formation energies, HOMO-LUMO gap energies, and intermolecular separations. Graphical Abstract Interaction of Ni(II) tetraazaannulene complex with elongated fullerenes.

  11. High Oxygen Reduction Reaction Performances of Cathode Materials Combining Polyoxometalates, Coordination Complexes, and Carboneous Supports.

    Science.gov (United States)

    Zhang, Shuangshuang; Oms, Olivier; Hao, Long; Liu, Rongji; Wang, Meng; Zhang, Yaqin; He, Hong-Yan; Dolbecq, Anne; Marrot, Jérôme; Keita, Bineta; Zhi, Linjie; Mialane, Pierre; Li, Bin; Zhang, Guangjin

    2017-11-08

    A series of carbonaceous-supported precious-metal-free polyoxometalate (POM)-based composites which can be easily synthesized on a large scale was shown to act as efficient cathode materials for the oxygen reduction reaction (ORR) in neutral or basic media via a four-electron mechanism with high durability. Moreover, exploiting the versatility of the considered system, its activity was optimized by the judicious choice of the 3d metals incorporated in the {(PW 9 ) 2 M 7 } (M = Co, Ni) POM core, the POM counterions and the support (thermalized triazine-based frameworks (TTFs), fluorine-doped TTF (TTF-F), reduced graphene oxide, or carbon Vulcan XC-72. In particular, for {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F, the overpotential required to drive the ORR compared well with those of Pt/C. This outstanding ORR electrocatalytic activity is linked with two synergistic effects due to the binary combination of the Cu and Ni centers and the strong interaction between the POM molecules and the porous and highly conducting TTF-F framework. To our knowledge, {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F represents the first example of POM-based noble-metal-free ORR electrocatalyst possessing both comparable ORR electrocatalytic activity and much higher stability than that of Pt/C in neutral medium.

  12. Dry season limnological conditions and basin geology exhibit complex relationships with δ13C and δ15N of carbon sources in four Neotropical floodplains.

    Science.gov (United States)

    Zaia Alves, Gustavo H; Hoeinghaus, David J; Manetta, Gislaine I; Benedito, Evanilde

    2017-01-01

    Studies in freshwater ecosystems are seeking to improve understanding of carbon flow in food webs and stable isotopes have been influential in this work. However, variation in isotopic values of basal production sources could either be an asset or a hindrance depending on study objectives. We assessed the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paraná, Pantanal, Araguaia, and Amazon). Limnological conditions exhibited greater variation within than among systems. δ15N differed among basins for most carbon sources, but δ13C did not (though high within-basin variability for periphyton, phytoplankton and particulate organic carbon was observed). Although δ13C and δ15N values exhibited significant correlations with some limnological factors within and among basins, those relationships differed among carbon sources. Regression trees for both carbon and nitrogen isotopes for all sources depicted complex and in some cases nested relationships, and only very limited similarity was observed among trees for different carbon sources. Although limnological conditions predicted variation in isotope values of carbon sources, we suggest the resulting models were too complex to enable mathematical corrections of source isotope values among sites based on these parameters. The importance of local conditions in determining variation in source isotope values suggest that isotopes may be useful for examining habitat use, dispersal and patch dynamics within heterogeneous floodplain ecosystems, but spatial variability in isotope values needs to be explicitly considered when testing ecosystem models of carbon flow in these systems.

  13. Formation and femtosecond photodissociation of Agn+andAun+ complexes with benzene and carbon monoxide

    Science.gov (United States)

    Popolan, Denisia M.; Bernhardt, Thorsten M.

    2009-02-01

    The reactions of free, size selected gold and silver cluster cations Agn+andAun+ ( n = 3, 5) with C 6H 6 as well as with a mixture of C 6H 6 and CO were investigated in a radio frequency ion trap under multiple collision condition. While benzene was found to react with all investigated metal clusters exhibiting size dependent adsorbate coverages, the coadsorption of C 6H 6 and CO was only observed on the gold clusters. Photodissociation experiments at 353 and 393 nm, respectively, provided indications for charge transfer induced fragmentation in the case of the silver cluster-benzene complexes. In particular, for Ag(CH)2+ the femtosecond time resolved fragmentation dynamics could be measured.

  14. Complex mountain terrain and disturbance history drive variation in forest aboveground live carbon density in the western Oregon Cascades, USA

    Science.gov (United States)

    Zald, Harold S.J.; Spies, Thomas A.; Seidl, Rupert; Pabst, Robert J.; Olsen, Keith A.; Steel, E. Ashley

    2016-01-01

    was also affected by finer scale topographic conditions associated with sheltered sites. Past wildfires only had a small influence on current ALC density, which may be a result of long times since fire and/or prevalence of non-stand replacing fire. Our results indicate that forest ALC density depends on a suite of multi-scale environmental drivers mediated by complex mountain topography, and that these relationships are dependent on stand age. The high and context-dependent spatial variability of forest ALC density has implications for quantifying forest carbon stores, establishing upper bounds of potential carbon sequestration, and scaling field data to landscape and regional scales. PMID:27041818

  15. Well log and seismic data analysis for complex pore-structure carbonate reservoir using 3D rock physics templates

    Science.gov (United States)

    Li, Hongbing; Zhang, Jiajia

    2018-04-01

    The pore structure in heterogeneous carbonate rock is usually very complex. This complex pore system makes the relationship between the velocity and porosity of the rock highly scattered, so that for the classical two-dimensional rock physics template (2D RPT) it is not enough to accurately describe the quantitative relationship between the rock elastic parameters of this kind of reservoir and its porosity and water saturation. Therefore it is possible to attribute the effect of pore type to that of the porosity or water saturation, and leads to great deviations when applying such a 2D RPT to predict the porosity and water saturation in seismic reservoir prediction and hydrocarbon detection. This paper first presents a method to establish a new three-dimensional rock physics template (3D RPT) by integrating the Gassmann equations and the porous rock physics model, and use it to characterize the quantitative relation between rock elastic properties and the reservoir parameters including the pore aspect ratio, porosity and water saturation, and to predict these parameters from the known elastic properties. The test results on the real logging and seismic inversion data show that the 3D RPT can accurately describe the variations of elastic properties with the porosity, water saturation and pore-structure parameters, and effectively improve the accuracy of reservoir parameters prediction.

  16. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    Science.gov (United States)

    Basiuk, Vladimir A.; Henao-Holguín, Laura Verónica; Álvarez-Zauco, Edgar; Bassiouk, María; Basiuk, Elena V.

    2013-04-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π-π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle-nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12,14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  17. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    Energy Technology Data Exchange (ETDEWEB)

    Basiuk, Vladimir A., E-mail: basiuk@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Henao-Holguín, Laura Verónica [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Álvarez-Zauco, Edgar [Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510, México D.F. (Mexico); Bassiouk, María [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Basiuk, Elena V. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico)

    2013-04-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  18. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    International Nuclear Information System (INIS)

    Basiuk, Vladimir A.; Henao-Holguín, Laura Verónica; Álvarez-Zauco, Edgar; Bassiouk, María; Basiuk, Elena V.

    2013-01-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  19. UV-Vis-IR spectral complex refractive indices and optical properties of brown carbon aerosol from biomass burning

    Science.gov (United States)

    Sumlin, Benjamin J.; Heinson, Yuli W.; Shetty, Nishit; Pandey, Apoorva; Pattison, Robert S.; Baker, Stephen; Hao, Wei Min; Chakrabarty, Rajan K.

    2018-02-01

    Constraining the complex refractive indices, optical properties and size of brown carbon (BrC) aerosols is a vital endeavor for improving climate models and satellite retrieval algorithms. Smoldering wildfires are the largest source of primary BrC, and fuel parameters such as moisture content, source depth, geographic origin, and fuel packing density could influence the properties of the emitted aerosol. We measured in situ spectral (375-1047 nm) optical properties of BrC aerosols emitted from smoldering combustion of Boreal and Indonesian peatlands across a range of these fuel parameters. Inverse Lorenz-Mie algorithms used these optical measurements along with simultaneously measured particle size distributions to retrieve the aerosol complex refractive indices (m = n + iκ). Our results show that the real part n is constrained between 1.5 and 1.7 with no obvious functionality in wavelength (λ), moisture content, source depth, or geographic origin. With increasing λ from 375 to 532 nm, κ decreased from 0.014 to 0.003, with corresponding increase in single scattering albedo (SSA) from 0.93 to 0.99. The spectral variability of κ follows the Kramers-Kronig dispersion relation for a damped harmonic oscillator. For λ ≥ 532 nm, both κ and SSA showed no spectral dependency. We discuss differences between this study and previous work. The imaginary part κ was sensitive to changes in FPD, and we hypothesize mechanisms that might help explain this observation.

  20. Energy and carbon emissions analysis and prediction of complex petrochemical systems based on an improved extreme learning machine integrated interpretative structural model

    International Nuclear Information System (INIS)

    Han, Yongming; Zhu, Qunxiong; Geng, Zhiqiang; Xu, Yuan

    2017-01-01

    Highlights: • The ELM integrated ISM (ISM-ELM) method is proposed. • The proposed method is more efficient and accurate than the ELM through the UCI data set. • Energy and carbon emissions analysis and prediction of petrochemical industries based ISM-ELM is obtained. • The proposed method is valid in improving energy efficiency and reducing carbon emissions of ethylene plants. - Abstract: Energy saving and carbon emissions reduction of the petrochemical industry are affected by many factors. Thus, it is difficult to analyze and optimize the energy of complex petrochemical systems accurately. This paper proposes an energy and carbon emissions analysis and prediction approach based on an improved extreme learning machine (ELM) integrated interpretative structural model (ISM) (ISM-ELM). ISM based the partial correlation coefficient is utilized to analyze key parameters that affect the energy and carbon emissions of the complex petrochemical system, and can denoise and reduce dimensions of data to decrease the training time and errors of the ELM prediction model. Meanwhile, in terms of the model accuracy and the training time, the robustness and effectiveness of the ISM-ELM model are better than the ELM through standard data sets from the University of California Irvine (UCI) repository. Moreover, a multi-inputs and single-output (MISO) model of energy and carbon emissions of complex ethylene systems is established based on the ISM-ELM. Finally, detailed analyses and simulations using the real ethylene plant data demonstrate the effectiveness of the ISM-ELM and can guide the improvement direction of energy saving and carbon emissions reduction in complex petrochemical systems.

  1. Immobilization of [Cu(bpy)2]Br2 complex onto a glassy carbon electrode modified with alpha-SiMo12O40(4-) and single walled carbon nanotubes: application to nanomolar detection of hydrogen peroxide and bromate.

    Science.gov (United States)

    Salimi, Abdollah; Korani, Aazam; Hallaj, Rahman; Khoshnavazi, Roshan; Hadadzadeh, Hasan

    2009-03-02

    A simple procedure has been used for preparation of modified glassy carbon electrode with carbon nanotubes and copper complex. Copper complex [Cu(bpy)(2)]Br(2) was immobilized onto glassy carbon (GC) electrode modified with silicomolybdate, alpha-SiMo(12)O(40)(4-) and single walled carbon nanotubes (SWCNTs). Copper complex and silicomolybdate irreversibly and strongly adsorbed onto GC electrode modified with CNTs. Electrostatic interactions between polyoxometalates (POMs) anions and Cu-complex, cations mentioned as an effective method for fabrication of three-dimensional structures. The modified electrode shows three reversible redox couples for polyoxometalate and one redox couple for Cu-complex at wide range of pH values. The electrochemical behavior, stability and electron transfer kinetics of the adsorbed redox couples were investigated using cyclic voltammetry. Due to electrostatic interaction, copper complex immobilized onto GC/CNTs/alpha-SiMo(12)O(40)(4-) electrode shows more stable voltammetric response compared to GC/CNTs/Cu-complex modified electrode. In comparison to GC/CNTs/Cu-complex the GC/CNTs/alpha-SiMo(12)O(40)(4-) modified electrodes shows excellent electrocatalytic activity toward reduction H(2)O(2) and BrO(3)(-) at more reduced overpotential. The catalytic rate constants for catalytic reduction hydrogen peroxide and bromate were 4.5(+/-0.2)x10(3) M(-1) s(-1) and 3.0(+/-0.10)x10(3) M(-1) s(-1), respectively. The hydrodynamic amperommetry technique at 0.08 V was used for detection of nanomolar concentration of hydrogen peroxide and bromate. Detection limit, sensitivity and linear concentration range proposed sensor for bromate and hydrogen peroxide detection were 1.1 nM and 6.7 nA nM(-1), 10 nM-20 microM, 1 nM, 5.5 nA nM(-1) and 10 nM-18 microM, respectively.

  2. Coupling of Carbon Dioxide with Epoxides Efficiently Catalyzed by Thioether-Triphenolate Bimetallic Iron(III) Complexes: Catalyst Structure-Reactivity Relationship and Mechanistic DFT Study

    KAUST Repository

    Della Monica, Francesco; Vummaleti, Sai V. C.; Buonerba, Antonio; Nisi, Assunta De; Monari, Magda; Milione, Stefano; Grassi, Alfonso; Cavallo, Luigi; Capacchione, Carmine

    2016-01-01

    A series of dinuclear iron(III)I complexes supported by thioether-triphenolate ligands have been prepared to attain highly Lewis acidic catalysts. In combination with tetrabutylammonium bromide (TBAB) they are highly active catalysts in the synthesis of cyclic organic carbonates through the coupling of carbon dioxide to epoxides with the highest initial turnover frequencies reported to date for the conversion of propylene oxide to propylene carbonate for iron-based catalysts (5200h-1; 120°C, 2MPa, 1h). In particular, these complexes are shown to be highly selective catalysts for the coupling of carbon dioxide to internal oxiranes affording the corresponding cyclic carbonates in good yield and with retention of the initial stereochemical configuration. A density functional theory (DFT) investigation provides a rational for the relative high activity found for these Fe(III) complexes, showing the fundamental role of the hemilabile sulfur atom in the ligand skeleton to promote reactivity. Notably, in spite of the dinuclear nature of the catalyst precursor only one metal center is involved in the catalytic cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Coupling of Carbon Dioxide with Epoxides Efficiently Catalyzed by Thioether-Triphenolate Bimetallic Iron(III) Complexes: Catalyst Structure-Reactivity Relationship and Mechanistic DFT Study

    KAUST Repository

    Della Monica, Francesco

    2016-08-25

    A series of dinuclear iron(III)I complexes supported by thioether-triphenolate ligands have been prepared to attain highly Lewis acidic catalysts. In combination with tetrabutylammonium bromide (TBAB) they are highly active catalysts in the synthesis of cyclic organic carbonates through the coupling of carbon dioxide to epoxides with the highest initial turnover frequencies reported to date for the conversion of propylene oxide to propylene carbonate for iron-based catalysts (5200h-1; 120°C, 2MPa, 1h). In particular, these complexes are shown to be highly selective catalysts for the coupling of carbon dioxide to internal oxiranes affording the corresponding cyclic carbonates in good yield and with retention of the initial stereochemical configuration. A density functional theory (DFT) investigation provides a rational for the relative high activity found for these Fe(III) complexes, showing the fundamental role of the hemilabile sulfur atom in the ligand skeleton to promote reactivity. Notably, in spite of the dinuclear nature of the catalyst precursor only one metal center is involved in the catalytic cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Hennebutte, H G; Goutal, E

    1921-07-04

    Materials such as coal, peat, or schist are subjected to a rising temperature in successive stages in apparatus in which the distillation products are withdrawn at each stage. For example in a three-stage process, the acid products of the first or low-temperature stage are fixed in a suitable reagent, the basic products from a second or higher-temperature stage are absorbed in an acid reagent, hydrocarbons being retained by solvents, while the third are subjected to a pyrogenation process carried out in a closed vessel. Wherein the material is subjected in stages to a rising temperature, the gasified products being withdrawn at each stage, and are prevented as far as possible from mixing with the carbonized products.

  5. Complex effects of fertilization on plant and herbivore performance in the presence of a plant competitor and activated carbon.

    Science.gov (United States)

    Mahdavi-Arab, Nafiseh; Meyer, Sebastian T; Mehrparvar, Mohsen; Weisser, Wolfgang W

    2014-01-01

    Plant-herbivore interactions are influenced by host plant quality which in turn is affected by plant growth conditions. Competition is the major biotic and nutrient availability a major abiotic component of a plant's growth environment. Yet, surprisingly few studies have investigated impacts of competition and nutrient availability on herbivore performance and reciprocal herbivore effects on plants. We studied growth of the specialist aphid, Macrosiphoniella tanacetaria, and its host plant tansy, Tanacetum vulgare, under experimental addition of inorganic and organic fertilizer crossed with competition by goldenrod, Solidago canadensis. Because of evidence that competition by goldenrod is mediated by allelopathic compounds, we also added a treatment with activated carbon. Results showed that fertilization increased, and competition with goldenrod decreased, plant biomass, but this was likely mediated by resource competition. There was no evidence from the activated carbon treatment that allelopathy played a role which instead had a fertilizing effect. Aphid performance increased with higher plant biomass and depended on plant growth conditions, with fertilization and AC increasing, and plant competition decreasing aphid numbers. Feedbacks of aphids on plant performance interacted with plant growth conditions in complex ways depending on the relative magnitude of the effects on plant biomass and aphid numbers. In the basic fertilization treatment, tansy plants profited from increased nutrient availability by accumulating more biomass than they lost due to an increased number of aphids under fertilization. When adding additional fertilizer, aphid numbers increased so high that tansy plants suffered and showed reduced biomass compared with controls without aphids. Thus, the ecological cost of an infestation with aphids depends on the balance of effects of growth conditions on plant and herbivore performance. These results emphasize the importance to investigate both

  6. Amazon rainforest exchange of carbon and subcanopy air flow: Manaus LBA site--a complex terrain condition.

    Science.gov (United States)

    Tóta, Julio; Fitzjarrald, David Roy; da Silva Dias, Maria A F

    2012-01-01

    On the moderately complex terrain covered by dense tropical Amazon Rainforest (Reserva Biologica do Cuieiras--ZF2--02°36'17.1'' S, 60°12'24.4'' W), subcanopy horizontal and vertical gradients of the air temperature, CO(2) concentration and wind field were measured for the dry and wet periods in 2006. We tested the hypothesis that horizontal drainage flow over this study area is significant and can affect the interpretation of the high carbon uptake rates reported by previous works at this site. A similar experimental design as the one by Tóta et al. (2008) was used with a network of wind, air temperature, and CO(2) sensors above and below the forest canopy. A persistent and systematic subcanopy nighttime upslope (positive buoyancy) and daytime downslope (negative buoyancy) flow pattern on a moderately inclined slope (12%) was observed. The microcirculations observed above the canopy (38 m) over the sloping area during nighttime presents a downward motion indicating vertical convergence and correspondent horizontal divergence toward the valley area. During the daytime an inverse pattern was observed. The micro-circulations above the canopy were driven mainly by buoyancy balancing the pressure gradient forces. In the subcanopy space the microcirculations were also driven by the same physical mechanisms but probably with the stress forcing contribution. The results also indicated that the horizontal and vertical scalar gradients (e.g., CO(2)) were modulated by these micro-circulations above and below the canopy, suggesting that estimates of advection using previous experimental approaches are not appropriate due to the tridimensional nature of the vertical and horizontal transport locally. This work also indicates that carbon budget from tower-based measurement is not enough to close the system, and one needs to include horizontal and vertical advection transport of CO(2) into those estimates.

  7. Amazon Rainforest Exchange of Carbon and Subcanopy Air Flow: Manaus LBA Site—A Complex Terrain Condition

    Directory of Open Access Journals (Sweden)

    Julio Tóta

    2012-01-01

    Full Text Available On the moderately complex terrain covered by dense tropical Amazon Rainforest (Reserva Biologica do Cuieiras—ZF2—02°36′17.1′′ S, 60°12′24.4′′ W, subcanopy horizontal and vertical gradients of the air temperature, CO2 concentration and wind field were measured for the dry and wet periods in 2006. We tested the hypothesis that horizontal drainage flow over this study area is significant and can affect the interpretation of the high carbon uptake rates reported by previous works at this site. A similar experimental design as the one by Tóta et al. (2008 was used with a network of wind, air temperature, and CO2 sensors above and below the forest canopy. A persistent and systematic subcanopy nighttime upslope (positive buoyancy and daytime downslope (negative buoyancy flow pattern on a moderately inclined slope (12% was observed. The microcirculations observed above the canopy (38 m over the sloping area during nighttime presents a downward motion indicating vertical convergence and correspondent horizontal divergence toward the valley area. During the daytime an inverse pattern was observed. The micro-circulations above the canopy were driven mainly by buoyancy balancing the pressure gradient forces. In the subcanopy space the microcirculations were also driven by the same physical mechanisms but probably with the stress forcing contribution. The results also indicated that the horizontal and vertical scalar gradients (e.g., CO2 were modulated by these micro-circulations above and below the canopy, suggesting that estimates of advection using previous experimental approaches are not appropriate due to the tridimensional nature of the vertical and horizontal transport locally. This work also indicates that carbon budget from tower-based measurement is not enough to close the system, and one needs to include horizontal and vertical advection transport of CO2 into those estimates.

  8. Complex effects of fertilization on plant and herbivore performance in the presence of a plant competitor and activated carbon.

    Directory of Open Access Journals (Sweden)

    Nafiseh Mahdavi-Arab

    Full Text Available Plant-herbivore interactions are influenced by host plant quality which in turn is affected by plant growth conditions. Competition is the major biotic and nutrient availability a major abiotic component of a plant's growth environment. Yet, surprisingly few studies have investigated impacts of competition and nutrient availability on herbivore performance and reciprocal herbivore effects on plants. We studied growth of the specialist aphid, Macrosiphoniella tanacetaria, and its host plant tansy, Tanacetum vulgare, under experimental addition of inorganic and organic fertilizer crossed with competition by goldenrod, Solidago canadensis. Because of evidence that competition by goldenrod is mediated by allelopathic compounds, we also added a treatment with activated carbon. Results showed that fertilization increased, and competition with goldenrod decreased, plant biomass, but this was likely mediated by resource competition. There was no evidence from the activated carbon treatment that allelopathy played a role which instead had a fertilizing effect. Aphid performance increased with higher plant biomass and depended on plant growth conditions, with fertilization and AC increasing, and plant competition decreasing aphid numbers. Feedbacks of aphids on plant performance interacted with plant growth conditions in complex ways depending on the relative magnitude of the effects on plant biomass and aphid numbers. In the basic fertilization treatment, tansy plants profited from increased nutrient availability by accumulating more biomass than they lost due to an increased number of aphids under fertilization. When adding additional fertilizer, aphid numbers increased so high that tansy plants suffered and showed reduced biomass compared with controls without aphids. Thus, the ecological cost of an infestation with aphids depends on the balance of effects of growth conditions on plant and herbivore performance. These results emphasize the importance

  9. Seasonal Dynamics of Dissolved Organic Carbon Under Complex Circulation Schemes on a Large Continental Shelf: The Northern South China Sea

    Science.gov (United States)

    Meng, Feifei; Dai, Minhan; Cao, Zhimian; Wu, Kai; Zhao, Xiaozheng; Li, Xiaolin; Chen, Junhui; Gan, Jianping

    2017-12-01

    We examined the distribution and seasonality of dissolved organic carbon (DOC) based on a large data set collected from the northern South China Sea (NSCS) shelf under complex circulation schemes influenced by river plume, coastal upwelling, and downwelling. The highest surface values of ˜117 μmol L-1 were observed nearshore in summer suggesting high DOC supplies from the river inputs, whereas the lowest surface values of ˜62 μmol L-1 were on the outer shelf in winter due to entrainment of DOC-poor subsurface water under strengthened vertical mixing. While the summer coastal upwelling brought lower DOC from offshore depth to the nearshore surface, the winter coastal downwelling delivered higher surface DOC to the midshelf deep waters from the inner shelf fueled by the China Coastal Current (CCC) transporting relatively high DOC from the East China Sea to the NSCS. The intensified winter downwelling generated a cross-shelf DOC transport of 3.1 × 1012 g C over a large shelf area, which induced a significant depression of the NSCS DOC inventory in winter relative to in autumn. In addition to the variable physical controls, net biological production of DOC was semiquantified in both the river plume (2.8 ± 3.0 μmol L-1) and coastal upwelling (3.1 ± 1.3 μmol L-1) in summer. We demonstrated that the NSCS shelf had various origins of DOC including riverine inputs, inter-shelf transport and in situ production. Via cross-shelf transport, the accumulated DOC would be exported to and stored in the deep ocean, suggesting that continental shelves are a potentially effective carbon sink.

  10. Age-related patterns of forest complexity and carbon storage in pine and aspen-birch ecosystems of northern Minnesota, USA

    Science.gov (United States)

    John B. Bradford; Douglas N. Kastendick

    2010-01-01

    Forest managers are seeking strategies to create stands that can adapt to new climatic conditions and simultaneously help mitigate increases in atmospheric CO2. Adaptation strategies often focus on enhancing resilience by maximizing forest complexity in terms of species composition and size structure, while mitigation involves sustaining carbon...

  11. Cooperative effect by monopodal silica-supported niobium com-plexes pairs enhancing catalytic cyclic carbonate production

    KAUST Repository

    D'Elia, Valerio

    2015-05-07

    Recent discoveries highlighted the activity and the intriguing mechanistic features of NbCl5 as a molecular catalyst for the cycloaddition of CO2 and epoxides under ambient conditions. This has inspired the preparation of novel silica supported Nb-species by reacting a molecular niobium precursor [NbCl5•OEt2] with silica dehydroxylated at 700 °C (SiO2-700) or at 200 oC (SiO2-200) to generate diverse surface complexes. The product of the reaction between SiO2-700 and [NbCl5•OEt2] was identified as a monopodal supported surface species [≡SiONbCl4•OEt2] (1a). The reactions of SiO2-200 with the niobium precursor, according to two different protocols, generated surface complexes 2a and 3a presenting significant, but different, populations of the monopodal surface complex along with bipodal [(≡SiO)2NbCl3•OEt2]. 93Nb SSNMR spectra of 1a-3a and 31P SSNMR on their PMe3 derivatives (1b-3b) led to the unambiguous assignment of 1a as a single site, monopodal Nb-species while 2a and 3a were found to present two distinct surface-supported components, with 2a being mostly monopodal [≡SiONbCl4•OEt2] and 3a being mostly bipodal [≡S ONbCl3•OEt2]. Double-quantum/single-quantum 31P NMR correlation experiment carried out on 2b supported the existence of vicinal Nb centers on the silica surface for this species. 1a-3a were active heterogeneous catalysts for the synthesis of propylene carbonate from CO2 and propylene oxide under mild catalytic conditions; the performance of 2a was found to significantly surpass that of 1a and 3a. With the support of a systematic DFT study carried out on model silica surfaces, the observed differences in catalytic efficiency were correlated with an unprece-dented cooperative effect between two neighboring Nb centers on the surface of 2a. This is in an excellent agreement with our previous discoveries regarding the mechanism of the NbCl5 catalyzed cycloaddition in the homogeneous phase.

  12. Cooperative effect by monopodal silica-supported niobium com-plexes pairs enhancing catalytic cyclic carbonate production

    KAUST Repository

    D'Elia, Valerio; Dong, Hailin; Rossini, Aaron J; Widdifield, Cory M.; Vummaleti, Sai V. C.; Minenkov, Yury; Poater, Albert; Abou-Hamad, Edy; Pelletier, Jeremie D. A.; Cavallo, Luigi; Emsley, Lyndon; Basset, Jean-Marie

    2015-01-01

    Recent discoveries highlighted the activity and the intriguing mechanistic features of NbCl5 as a molecular catalyst for the cycloaddition of CO2 and epoxides under ambient conditions. This has inspired the preparation of novel silica supported Nb-species by reacting a molecular niobium precursor [NbCl5•OEt2] with silica dehydroxylated at 700 °C (SiO2-700) or at 200 oC (SiO2-200) to generate diverse surface complexes. The product of the reaction between SiO2-700 and [NbCl5•OEt2] was identified as a monopodal supported surface species [≡SiONbCl4•OEt2] (1a). The reactions of SiO2-200 with the niobium precursor, according to two different protocols, generated surface complexes 2a and 3a presenting significant, but different, populations of the monopodal surface complex along with bipodal [(≡SiO)2NbCl3•OEt2]. 93Nb SSNMR spectra of 1a-3a and 31P SSNMR on their PMe3 derivatives (1b-3b) led to the unambiguous assignment of 1a as a single site, monopodal Nb-species while 2a and 3a were found to present two distinct surface-supported components, with 2a being mostly monopodal [≡SiONbCl4•OEt2] and 3a being mostly bipodal [≡S ONbCl3•OEt2]. Double-quantum/single-quantum 31P NMR correlation experiment carried out on 2b supported the existence of vicinal Nb centers on the silica surface for this species. 1a-3a were active heterogeneous catalysts for the synthesis of propylene carbonate from CO2 and propylene oxide under mild catalytic conditions; the performance of 2a was found to significantly surpass that of 1a and 3a. With the support of a systematic DFT study carried out on model silica surfaces, the observed differences in catalytic efficiency were correlated with an unprece-dented cooperative effect between two neighboring Nb centers on the surface of 2a. This is in an excellent agreement with our previous discoveries regarding the mechanism of the NbCl5 catalyzed cycloaddition in the homogeneous phase.

  13. Complex carbon cycling processes and pathways in a tropical coastal marine environment (Saco do Mamangua, RJ - Brazil)

    Science.gov (United States)

    Giorgioni, M.; Jovane, L.; Millo, C.; Sawakuchi, H. O.; Bertassoli, D. J., Jr.; Gamba Romano, R.; Pellizari, V.; Castillo Franco, D.; Krusche, A. V.

    2016-12-01

    The Saco do Mamangua is a narrow and elongated gulf located along the southeastern coast of Brazil, in the state of Rio de Janeiro (RJ). It is surrounded by high relieves, which form a peculiar environment called riá, with little river input and limited water exchange with the Atlantic Ocean. These features make the Saco do Mamangua an ideal environment to study sedimentary carbon cycling under well-constrained boundary conditions in order to investigate if tropical coastal environments serve dominantly as potential carbon sinks or sources. In this work we integrate geochemical data from marine sediments and pore waters in the Saco do Mamangua with mapping of benthic microbial communities, in order to unravel the biogeochemical carbon cycling linked to the production of biogenic methane. Our results reveal that carbon cycling occurs in two parallel pathways. The Saco do Mamangua receives organic carbon both by surface runoff and by primary production in the water column. A large part of this organic carbon is buried within the sediment resulting in the production of biogenic methane, which gives rise to methane seepages at the sea floor. These methane seeps sustain methanotrophic microbial communities in the sediment pore water, but also escapes into the atmosphere by ebullition. Consequently, the sediments of Saco do Mamangua acts simultaneously as carbon sink and carbon source. Future work will allow us to accurately quantify the actual carbon fluxes and calculate the net carbon balance in the local environment.

  14. Spatial complexities in aboveground carbon stocks of a semi-arid mangrove community: A remote sensing height-biomass-carbon approach

    KAUST Repository

    Hickey, S.M.; Callow, N.J.; Phinn, S.; Lovelock, C.E.; Duarte, Carlos M.

    2017-01-01

    Mangroves are integral to ecosystem services provided by the coastal zone, in particular carbon (C) sequestration and storage. Allometric relationships linking mangrove height to estimated biomass and C stocks have been developed from field sampling

  15. Effects of cytotoxic cis- and trans-diammine monochlorido platinum(II) complexes on selenium-dependent redox enzymes and DNA

    Czech Academy of Sciences Publication Activity Database

    Lemmerhirt, H.; Behnisch, S.; Bodtke, A.; Lillig, Ch.H.; Pazderová, L.; Kašpárková, Jana; Brabec, Viktor; Bednarski, P.J.

    2018-01-01

    Roč. 178, JAN2018 (2018), s. 94-105 ISSN 0162-0134 R&D Projects: GA ČR GA17-09436S Institutional support: RVO:68081707 Keywords : glutathione-peroxidase * thioredoxin reductase Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 3.348, year: 2016

  16. Platinum(II) Complexes of 2-(Dimethylamino)ethylselenolate-Donor-Acceptor Inter-Ligand Interactions as Evident from Experimental and TD-DFT Computational Analysis

    Czech Academy of Sciences Publication Activity Database

    Dey, S.; Jain, V. K.; Knoedler, A.; Kaim, W.; Záliš, Stanislav

    č. 11 (2001), s. 2965-2973 ISSN 1434-1948 R&D Projects: GA MŠk ME 439 Institutional research plan: CEZ:AV0Z4040901 Keywords : platinum * selenium * NMR spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.475, year: 2001

  17. Tetradentate Schiff base platinum(II) complexes as new class of phosphorescent materials for high-efficiency and white-light electroluminescent devices.

    Science.gov (United States)

    Che, Chi-Ming; Chan, Siu-Chung; Xiang, Hai-Feng; Chan, Michael C W; Liu, Yu; Wang, Yue

    2004-07-07

    The capabilities of readily prepared and sublimable Pt(II) Schiff base triplet emitters as OLED dopants have been examined; maximum luminous and power efficiencies and luminance of 31 cd A(-1), 14 lm W(-1), and 23,000 cd m(-2), respectively, and white EL (CIE: 0.33, 0.35) by simultaneous host/dopant emission, have been achieved.

  18. Evolution of chemical and isotopic composition of inorganic carbon in a complex semi-arid zone environment: Consequences for groundwater dating using radiocarbon

    Science.gov (United States)

    Meredith, K. T.; Han, L. F.; Hollins, S. E.; Cendón, D. I.; Jacobsen, G. E.; Baker, A.

    2016-09-01

    Estimating groundwater age is important for any groundwater resource assessment and radiocarbon (14C) dating of dissolved inorganic carbon (DIC) can provide this information. In semi-arid zone (i.e. water-limited environments), there are a multitude of reasons why 14C dating of groundwater and traditional correction models may not be directly transferable. Some include; (1) the complex hydrological responses of these systems that lead to a mixture of different ages in the aquifer(s), (2) the varied sources, origins and ages of organic matter in the unsaturated zone and (3) high evaporation rates. These all influence the evolution of DIC and are not easily accounted for in traditional correction models. In this study, we determined carbon isotope data for; DIC in water, carbonate minerals in the sediments, sediment organic matter, soil gas CO2 from the unsaturated zone, and vegetation samples. The samples were collected after an extended drought, and again after a flood event, to capture the evolution of DIC after varying hydrological regimes. A graphical method (Han et al., 2012) was applied for interpretation of the carbon geochemical and isotopic data. Simple forward mass-balance modelling was carried out on key geochemical processes involving carbon and agreed well with observed data. High values of DIC and δ13CDIC, and low 14CDIC could not be explained by a simple carbonate mineral-CO2 gas dissolution process. Instead it is suggested that during extended drought, water-sediment interaction leads to ion exchange processes within the top ∼10-20 m of the aquifer which promotes greater calcite dissolution in saline groundwater. This process was found to contribute more than half of the DIC, which is from a mostly 'dead' carbon source. DIC is also influenced by carbon exchange between DIC in water and carbonate minerals found in the top 2 m of the unsaturated zone. This process occurs because of repeated dissolution/precipitation of carbonate that is dependent on

  19. The electrochemical behavior of Co(TPTZ)2 complex on different carbon based electrodes modified with TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Ortaboy, Sinem; Atun, Gülten

    2015-01-01

    Electrochemical behavior of cobalt (II) complex with the N-donor ligand 2,2′-bipyridyl-1,3,5-tripyridyl-s-triazine (TPTZ) was investigated to elucidate the electron-proton transfer mechanisms. The electrochemical response of the complex was studied using square-wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) techniques. A conventional three-electrode system, consisting of glassy carbon (GCE), TiO 2 modified glassy carbon (T/GCE), carbon paste (CPE) and TiO 2 modified carbon paste (T/CPE) working electrodes were employed. The ligand/metal ratio and stability constant of the complex as well as the mechanisms of the electrode processes were elucidated by examining the effects of pH, ligand concentration and frequency on the voltammograms. The EIS results indicated that the samples modified with TiO 2 had the higher charge transfer resistance than that of the bare electrodes and also suggested that the electroactivity of the electrode surfaces increased in the following order, T/CPE > CPE > T/GCE > GCE. The surface morphology of the working electrodes was also characterized by atomic force microscopy (AFM). The values of surface roughness parameters were found to be consistent with the results obtained by EIS experiments. - Graphical abstract: Schematic illustration of the experimental process. - Highlights: • Electrochemical behavior of Co(TPTZ) 2 complex studied by SWV and EIS techniques. • GCE, CPE T/GCE and T/CPE were used as working electrodes for comparative studies. • The surface morphologies of the electrodes were characterized by AFM. • Mechanisms were proposed from the effects of pH, ligand concentration and frequency. • EIS and morphologic relationships of the surfaces were established successfully

  20. The electrochemical behavior of Co(TPTZ){sub 2} complex on different carbon based electrodes modified with TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ortaboy, Sinem, E-mail: ortaboy@istanbul.edu.tr; Atun, Gülten, E-mail: gatun@istanbul.edu.tr

    2015-04-15

    Electrochemical behavior of cobalt (II) complex with the N-donor ligand 2,2′-bipyridyl-1,3,5-tripyridyl-s-triazine (TPTZ) was investigated to elucidate the electron-proton transfer mechanisms. The electrochemical response of the complex was studied using square-wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) techniques. A conventional three-electrode system, consisting of glassy carbon (GCE), TiO{sub 2} modified glassy carbon (T/GCE), carbon paste (CPE) and TiO{sub 2} modified carbon paste (T/CPE) working electrodes were employed. The ligand/metal ratio and stability constant of the complex as well as the mechanisms of the electrode processes were elucidated by examining the effects of pH, ligand concentration and frequency on the voltammograms. The EIS results indicated that the samples modified with TiO{sub 2} had the higher charge transfer resistance than that of the bare electrodes and also suggested that the electroactivity of the electrode surfaces increased in the following order, T/CPE > CPE > T/GCE > GCE. The surface morphology of the working electrodes was also characterized by atomic force microscopy (AFM). The values of surface roughness parameters were found to be consistent with the results obtained by EIS experiments. - Graphical abstract: Schematic illustration of the experimental process. - Highlights: • Electrochemical behavior of Co(TPTZ){sub 2} complex studied by SWV and EIS techniques. • GCE, CPE T/GCE and T/CPE were used as working electrodes for comparative studies. • The surface morphologies of the electrodes were characterized by AFM. • Mechanisms were proposed from the effects of pH, ligand concentration and frequency. • EIS and morphologic relationships of the surfaces were established successfully.

  1. Inhibition of precipitation of carbonate apatite by trisodium citrate analysed in base of the formation of chemical complexes in growth solution

    Energy Technology Data Exchange (ETDEWEB)

    Prywer, Jolanta, E-mail: jolanta.prywer@p.lodz.pl [Institute of Physics, Lodz University of Technology, ul. Wólczańska 219, 93-005 Łódź (Poland); Olszynski, Marcin [Institute of Physics, Lodz University of Technology, ul. Wólczańska 219, 93-005 Łódź (Poland); Mielniczek-Brzóska, Ewa [Institute of Chemistry, Environment Protection and Biotechnology, Jan Długosz University of Częstochowa, ul. Armii Krajowej 13/15, 42-200 Częstochowa (Poland)

    2015-11-15

    Effect of trisodium citrate on the precipitation of carbonate apatite is studied. The experimental series are performed in the solution of artificial urine. The investigations are related to infectious urinary stones formation as carbonate apatite is one of the main components of this kind of stones. To mimic a real infection in urinary tract the aqueous ammonia solution was added to the solution of artificial urine. The spectrophotometric results demonstrate that trisodium citrate increases induction time with respect to carbonate apatite formation and decreases the efficiency of carbonate apatite precipitation. The inhibitory effect of trisodium citrate on the precipitation of carbonate apatite is explained in base of chemical speciation analysis. Such an analysis demonstrates that the inhibitory effect is mainly related with the fact that trisodium citrate binds Ca{sup 2+} ions and causes the formation of CaCit{sup −} and Ca{sub 10}(PO{sub 4}){sub 6}CO{sub 3} complexes. Trisodium citrate binds Ca{sup 2+} ions in the range of pH from 6 to 9.5 for which carbonate apatite is favored to be formed. - Highlights: • Trisodium citrate (TC) increases induction time of carbonate apatite (CA) formation. • TC decreases the efficiency of CA precipitation. • The inhibitory effect of TC is explained in base of chemical speciation analysis. • The inhibitory effect is mainly related with the fact that TC binds Ca{sup 2+} ions. • TC binds Ca{sup 2+} ions in the range of pH from 6 to 9.5 for which CA is formed.

  2. The influence of dissolved H2O content in supercritical carbon dioxide to the inclusion complexes formation of ketoprofen/β-cyclodextrin

    Science.gov (United States)

    Goenawan, Joshua; Trisanti, P. N.; Sumarno

    2015-12-01

    This work studies the relation between dissolved H2O content in supercritical carbon dioxide (SC-CO2) with the formation of ketoprofen (KP)/β-cyclodextrin(CD) inclusion complexes. The process involves a physical mixture of these two compounds into contact with the supercritical carbon dioxide which had been previously saturated with H2O over a certain duration. The pressure used for saturation process is 130 bar and saturation temperature was ranged between 30 °C to 50 °C. The inclusion process was achieved by keeping it for 2 hours at 160 bar and 200 bar with inclusion temperature of 50 °C. The results enable us to suggest explanations for the inclusion formation. The inclusion complexes can be formed by contacting the dissolved H2O in SC-CO2 to the physical mixture of KP and CD. An increase in the temperature of saturation process resulted in an increase of dissolved H2O content in the supercritical carbon dioxide. The increasing levels of this water soluble resulted an increase in the inclusion complexes that has been formed. The formation of inclusion complexes includes the water molecules enhancing the emptying of the CD cavities and being replaced by KP, towards a more stable energy state. The drug release used for analyzing the dissolution rate of the KP/CD complexes. The results vary from 79,85% to 99,98% after 45 minutes which is above the rate that has been assigned by Farmakope Indonesia at 70% dissolution rate for KP. The use of SC-CO2 offers a new methods for increasing the rate of dissolution of drugs that are hydrophobic such as KP. CO2 used as a supercritical fluid because of its relatively low cost, easily obtainable supercritical conditions, and lack of toxicity. The material samples were characterized by DSC and Spectrophotometer UV-vis technique.

  3. How does complex terrain influence responses of carbon and water cycle processes to climate variability and climate change? (Invited)

    Science.gov (United States)

    Bond, B. J.; Peterson, K.; McKane, R.; Lajtha, K.; Quandt, D. J.; Allen, S. T.; Sell, S.; Daly, C.; Harmon, M. E.; Johnson, S. L.; Spies, T.; Sollins, P.; Abdelnour, A. G.; Stieglitz, M.

    2010-12-01

    We are pursuing the ambitious goal of understanding how complex terrain influences the responses of carbon and water cycle processes to climate variability and climate change. Our studies take place in H.J. Andrews Experimental Forest, an LTER (Long Term Ecological Research) site situated in Oregon’s central-western Cascade Range. Decades of long-term measurements and intensive research have revealed influences of topography on vegetation patterns, disturbance history, and hydrology. More recent research has shown surprising interactions between microclimates and synoptic weather patterns due to cold air drainage and pooling in mountain valleys. Using these data and insights, in addition to a recent LiDAR (Light Detection and Ranging) reconnaissance and a small sensor network, we are employing process-based models, including “SPA” (Soil-Plant-Atmosphere, developed by Mathew Williams of the University of Edinburgh), and “VELMA” (Visualizing Ecosystems for Land Management Alternatives, developed by Marc Stieglitz and colleagues of the Georgia Institute of Technology) to focus on two important features of mountainous landscapes: heterogeneity (both spatial and temporal) and connectivity (atmosphere-canopy-hillslope-stream). Our research questions include: 1) Do fine-scale spatial and temporal heterogeneity result in emergent properties at the basin scale, and if so, what are they? 2) How does connectivity across ecosystem components affect system responses to climate variability and change? Initial results show that for environmental drivers that elicit non-linear ecosystem responses on the plot scale, such as solar radiation, soil depth and soil water content, fine-scale spatial heterogeneity may produce unexpected emergent properties at larger scales. The results from such modeling experiments are necessarily a function of the supporting algorithms. However, comparisons based on models such as SPA and VELMA that operate at much different spatial scales

  4. Bis(di-2-pyridylamine-κ2N2,N2'platinum(II dibromide monohydrate

    Directory of Open Access Journals (Sweden)

    Kwang Ha

    2012-04-01

    Full Text Available The asymmetric unit of the title compound, [Pt(C10H9N32]Br2·H2O, contains two crystallographically independent half-molecules of the cationic PtII complex, two Br− anions and a lattice water molecule; an inversion centre is located at the centroid of each complex. Each PtII ion is four-coordinated in an essentially square-planar environment by four pyridine N atoms derived from the two chelating di-2-pyridylamine (dpa ligands, and the PtN4 unit is exactly planar. The chelate ring formed by the dpa ligand displays a boat conformation, with dihedral angles between the pyridine rings of 35.9 (2 and 41.0 (2°. The complex cations, Br− anions and solvent water molecules are linked by O—H...Br, N—H...Br, C—H...O and C—H...Br hydrogen bonds, forming a three-dimensional network.

  5. Free Energy Minimization Calculation of Complex Chemical Equilibria. Reduction of Silicon Dioxide with Carbon at High Temperature.

    Science.gov (United States)

    Wai, C. M.; Hutchinson, S. G.

    1989-01-01

    Discusses the calculation of free energy in reactions between silicon dioxide and carbon. Describes several computer programs for calculating the free energy minimization and their uses in chemistry classrooms. Lists 16 references. (YP)

  6. Cage-Like Porous Carbon with Superhigh Activity and Br2 -Complex-Entrapping Capability for Bromine-Based Flow Batteries.

    Science.gov (United States)

    Wang, Chenhui; Lai, Qinzhi; Xu, Pengcheng; Zheng, Daoyuan; Li, Xianfeng; Zhang, Huamin

    2017-06-01

    Bromine-based flow batteries receive wide attention in large-scale energy storage because of their attractive features, such as high energy density and low cost. However, the Br 2 diffusion and relatively low activity of Br 2 /Br - hinder their further application. Herein, a cage-like porous carbon (CPC) with specific pore structure combining superhigh activity and Br 2 -complex-entrapping capability is designed and fabricated. According to the results of density functional theory (DFT) calculation, the pore size of the CPC (1.1 nm) is well designed between the size of Br - (4.83 Å), MEP + (9.25 Å), and Br 2 complex (MEPBr 3 12.40 Å), wherein Br - is oxidized to Br 2 , which forms a Br 2 complex with the complexing agent immediately and is then entrapped in the cage via pore size exclusion. In addition, the active sites produced during the carbon dioxide activation process dramatically accelerate the reaction rate of Br 2 /Br - . In this way, combining a high Br 2 -entrapping-capability and high specific surface areas, the CPC shows very impressive performance. The zinc bromine flow battery assembled with the prepared CPC shows a Coulombic efficiency of 98% and an energy efficiency of 81% at the current density of 80 mA cm -2 , which are among the highest values ever reported. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Synthetic and mechanistic study of oxycarbene-like coupling reaction patterns of actinide eta2-acyl complexes with carbon monoxide and isocyanides

    International Nuclear Information System (INIS)

    Moloy, K.G.; Fagan, P.J.; Manriquez, J.M.; Marks, T.J.

    1986-01-01

    This contribution reports the synthesis and characterization of the ylide complexes Cp' 2 Th[OC(CH 2 -t-Bu)C-(PR 3 )O[(Cl) (Cp' = eta 5 -C 5 Me 5 ; R = Me, Ph) formed by the carbonylation of Cp' 2 Th(Cl)(eta 2 -COCH 2 -t-Bu) (1) in the presence of phosphines. Isotopic tracer studies with 13 CO indicate that the labeled carbon atom is incorporated regiospecifically at the ylide α-carbon atom position. The carbonylation of 1 to yield the enedionediolate (Cp' 2 Th[OC(CH 2 -t-Bu)CO](Cl)] 2 (2) or the ylide complexes was found to obey a second-order rate law where rate = kP/sub CO/[1]; k = 1.50 (5) x 10 -5 min -1 torr -1 for both carbonylations at 30.8 0 C. The rate of formation of the ylide complexes was also found to be independent of solvent, phosphine concentration, and type of phosphine used. The carbonylation of 1 is therefore inferred to involve a rate-determining coupling of CO with the acyl to yield an intermediate ketene or ketene-like complex. 51 references, 4 figures, 3 tables

  8. 13C and 17O NMR binding constant studies of uranyl carbonate complexes in near-neutral aqueous solution. Yucca Mountain Project Milestone Report 3351

    International Nuclear Information System (INIS)

    Clark, D.L.; Newton, T.W.; Palmer, P.D.; Zwick, B.D.

    1995-01-01

    Valuable structural information, much of it unavailable by other methods, can be obtained about complexes in solution through NMR spectroscopy. From chemical shift and intensity measurements of complexed species, NMR can serve as a species-specific structural probe for molecules in solution and can be used to validate thermodynamic constants used in geochemical modeling. Fourier-transform nuclear magnetic resonance (FT-NMR) spectroscopy has been employed to study the speciation of uranium(VI) ions in aqueous carbonate solutions as a function of pH, ionic strength, carbonate concentration, uranium concentration, and temperature. Carbon-13 and oxygen-17 NMR spectroscopy were used to monitor the fractions, and hence thermodynamic binding constants of two different uranyl species U0 2 (CO 3 ) 3 4- and (UO 2 ) 3 (CO 3 ) 6 6- in aqueous solution. Synthetic buffer solutions were prepared under the ionic strength conditions used in the NMR studies in order to obtain an accurate measure of the hydrogen ion concentration, and a discussion of pH = -log(a H + ) versus p[H] = -log[H+] is provided. It is shown that for quantitative studies, the quantity p[H] needs to be used. Fourteen uranium(VI) binding constants recommended by the OECD NEA literature review were corrected to the ionic strengths employed in the NMR study using specific ion interaction theory (SIT), and the predicted species distributions were compared with the actual species observed by multinuclear NMR. Agreement between observed and predicted stability fields is excellent. This establishes the utility of multinuclear NMR as a species-specific tool for the study of the actinide carbonate complexation constants, and serves as a means for validating the recommendations provided by the OECD NEA

  9. Bright, Multi-responsive, Sky-Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework.

    Science.gov (United States)

    Liu, Lijie; Wang, Xiang; Wang, Nan; Peng, Tai; Wang, Suning

    2017-07-24

    A new class of highly efficient and stable, blue-phosphorescent Pt II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching-from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt II compounds yields UV-light-induced phosphorescence enhancement and color switching. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. MEDUSA-2.0: an intermediate complexity biogeochemical model of the marine carbon cycle for climate change and ocean acidification studies

    Directory of Open Access Journals (Sweden)

    A. Yool

    2013-10-01

    Full Text Available MEDUSA-1.0 (Model of Ecosystem Dynamics, nutrient Utilisation, Sequestration and Acidification was developed as an "intermediate complexity" plankton ecosystem model to study the biogeochemical response, and especially that of the so-called "biological pump", to anthropogenically driven change in the World Ocean (Yool et al., 2011. The base currency in this model was nitrogen from which fluxes of organic carbon, including export to the deep ocean, were calculated by invoking fixed C:N ratios in phytoplankton, zooplankton and detritus. However, due to anthropogenic activity, the atmospheric concentration of carbon dioxide (CO2 has significantly increased above its natural, inter-glacial background. As such, simulating and predicting the carbon cycle in the ocean in its entirety, including ventilation of CO2 with the atmosphere and the resulting impact of ocean acidification on marine ecosystems, requires that both organic and inorganic carbon be afforded a more complete representation in the model specification. Here, we introduce MEDUSA-2.0, an expanded successor model which includes additional state variables for dissolved inorganic carbon, alkalinity, dissolved oxygen and detritus carbon (permitting variable C:N in exported organic matter, as well as a simple benthic formulation and extended parameterizations of phytoplankton growth, calcification and detritus remineralisation. A full description of MEDUSA-2.0, including its additional functionality, is provided and a multi-decadal spin-up simulation (1860–2005 is performed. The biogeochemical performance of the model is evaluated using a diverse range of observational data, and MEDUSA-2.0 is assessed relative to comparable models using output from the Coupled Model Intercomparison Project (CMIP5.

  11. Response of the carbon cycle in an intermediate complexity model to the different climate configurations of the last nine interglacials

    Directory of Open Access Journals (Sweden)

    N. Bouttes

    2018-03-01

    Full Text Available Atmospheric CO2 levels during interglacials prior to the Mid-Brunhes Event (MBE,  ∼  430 ka BP were around 40 ppm lower than after the MBE. The reasons for this difference remain unclear. A recent hypothesis proposed that changes in oceanic circulation, in response to different external forcings before and after the MBE, might have increased the ocean carbon storage in pre-MBE interglacials, thus lowering atmospheric CO2. Nevertheless, no quantitative estimate of this hypothesis has been produced up to now. Here we use an intermediate complexity model including the carbon cycle to evaluate the response of the carbon reservoirs in the atmosphere, ocean and land in response to the changes of orbital forcings, ice sheet configurations and atmospheric CO2 concentrations over the last nine interglacials. We show that the ocean takes up more carbon during pre-MBE interglacials in agreement with data, but the impact on atmospheric CO2 is limited to a few parts per million. Terrestrial biosphere is simulated to be less developed in pre-MBE interglacials, which reduces the storage of carbon on land and increases atmospheric CO2. Accounting for different simulated ice sheet extents modifies the vegetation cover and temperature, and thus the carbon reservoir distribution. Overall, atmospheric CO2 levels are lower during these pre-MBE simulated interglacials including all these effects, but the magnitude is still far too small. These results suggest a possible misrepresentation of some key processes in the model, such as the magnitude of ocean circulation changes, or the lack of crucial mechanisms or internal feedbacks, such as those related to permafrost, to fully account for the lower atmospheric CO2 concentrations during pre-MBE interglacials.

  12. Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential

    Science.gov (United States)

    Tournassat, C.; Tinnacher, R. M.; Grangeon, S.; Davis, J. A.

    2018-01-01

    The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonite edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites ('spillover' effect). A series of U(VI) - Na-montmorillonite batch adsorption experiments was conducted as a function of pH, with variable U(VI), Ca, and dissolved carbonate concentrations. Based on the experimental data, a new type of surface complexation model (SCM) was developed for montmorillonite, that specifically accounts for the spillover effect using the edge surface speciation model by Tournassat et al. (2016a). The SCM allows for a prediction of U(VI) adsorption under varying chemical conditions with a minimum number of fitting parameters, not only for our own experimental results, but also for a number of published data sets. The model agreed well with many of these datasets without introducing a second site type or including the formation of ternary U(VI)-carbonato surface complexes. The model predictions were greatly impacted by utilizing analytical measurements of dissolved inorganic carbon (DIC) concentrations in individual sample solutions rather than assuming solution equilibration with a specific partial pressure of CO2, even when the gas phase was

  13. Assignment of hyperfine shifted haem methyl carbon resonances in paramagnetic low-spin met-cyano complex of sperm whale myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yasuhiko

    1987-09-28

    The hyperfine shifted resonances arising from all four individual haem carbons of the paramagnetic low-spin met-cyano complex of sperm whale myoglobin have been clearly identified and assigned for the first time with the aid of /sup 1/H-/sup 13/C heteronuclear chemical shift correlated spectroscopy. Alteration of the in-plane symmetry of the electronic structure of haem induced by the ligation of proximal histidyl imidazole spreads the haem carbon resonances to 32 ppm at 22/sup 0/C, indicating the sensitivity of those resonances to the haem electronic/molecular structure. Those resonances are potentially powerful probes in characterizing the nature of haem electronic structure. 25 refs.; 2 figs.; 1 table.

  14. A stability comparison of redox-active layers produced by chemical coupling of an osmium redox complex to pre-functionalized gold and carbon electrodes

    International Nuclear Information System (INIS)

    Boland, Susan; Foster, Kevin; Leech, Donal

    2009-01-01

    The production of stable redox active layers on electrode surfaces is a key factor for the development of practical electronic and electrochemical devices. Here, we report on a comparison of the stability of redox layers formed by covalently coupling an osmium redox complex to pre-functionalized gold and graphite electrode surfaces. Pre-treatment of gold and graphite electrodes to provide surface carboxylic acid groups is achieved via classical thiolate self-assembled monolayer formation on gold surfaces and the electro-reduction of an in situ generated aryldiazonium salt from 4-aminobenzoic acid on gold, glassy carbon and graphite surfaces. These surfaces have been characterized by AFM and electrochemical blocking studies. The surface carboxylate is then used to tether an osmium complex, [Os(2,2'-bipyridyl) 2 (4-aminomethylpyridine)Cl]PF 6 , to provide a covalently bound redox active layer, E 0 '' of 0.29 V (vs. Ag/AgCl in phosphate buffer, pH 7.4), on the pre-treated electrodes. The aryldiazonium salt-treated carbon-based surfaces showed the greatest stability, represented by a decrease of <5% in the peak current for the Os(II/III) redox transition of the immobilized complex over a 3-day period, compared to a decrease of 19% and 14% for the aryldiazonium salt treated and thiolate treated gold surfaces, respectively, over the same period

  15. Propensity of a single-walled carbon nanotube-peptide to mimic a KK10 peptide in an HLA-TCR complex

    Science.gov (United States)

    Feng, Mei; Bell, David R.; Zhou, Ruhong

    2017-12-01

    The application of nanotechnology to improve disease diagnosis, treatment, monitoring, and prevention is the goal of nanomedicine. We report here a theoretical study of a functionalized single-walled carbon nanotube (CNT) mimic binding to a human leukocyte antigen-T cell receptor (HLA-TCR) immune complex as a first attempt of a potential nanomedicine for human immunodeficiency virus (HIV) vaccine development. The carbon nanotube was coated with three arginine residues to imitate the HIV type 1 immunodominant viral peptide KK10 (gag 263-272: KRWIILGLNK), named CNT-peptide hereafter. Through molecular dynamics simulations, we explore the CNT-peptide and KK10 binding to an important HLA-TCR complex. Our results suggest that the CNT-peptide and KK10 bind comparably to the HLA-TCR complex, but the CNT-peptide forms stronger interactions with the TCR. Desorption simulations highlight the innate flexibility of KK10 over the CNT-peptide, resulting in a slightly higher desorption energy required for KK10 over the CNT-peptide. Our findings indicate that the designed CNT-peptide mimic has favorable propensity to activate TCR pathways and should be further explored to understand therapeutic potential.

  16. 1,2,4-Triazines in the Synthesis of Bipyridine Bisphenolate ONNO Ligands and Their Highly Luminescent Tetradentate Pt(II) Complexes for Solution-Processable OLEDs.

    Science.gov (United States)

    Pander, Piotr; Bulmer, Rachel; Martinscroft, Ross; Thompson, Stuart; Lewis, Frank W; Penfold, Thomas J; Dias, Fernando B; Kozhevnikov, Valery N

    2018-04-02

    This article describes a convenient method for the synthesis of ONNO-type tetradentate 6,6'-bis(2-phenoxy)-2,2'-bipyridine (bipyridine bisphenolate, BpyBph) ligands and their platinum(II) complexes. The methodology includes the synthesis of 1,2,4-triazine precursors followed by their transformation to functionalized pyridines by the Boger reaction. Two complementary routes employing 3,3'- and 5,5'-bis-triazines allow a modification of the central pyridine rings in different positions, which was exemplified by the introduction of cyclopentene rings. The new ligands were used to prepare highly luminescent ONNO-type Pt(II) complexes. The position of the cyclopentene rings significantly influences the solubility and photophysical properties of these complexes. Derivatives with closely positioned cyclopentene rings are soluble in organic solvents and proved to be the best candidate for solution-processable organic light-emitting devices (OLEDs), showing efficient single-dopant candlelight electroluminescence.

  17. Ultraviolet-B radiation mobilizes uranium from uranium-dissolved organic carbon complexes in aquatic systems, demonstrated by asymmetrical flow field-flow fractionation.

    Science.gov (United States)

    Nehete, Sachin Vilas; Christensen, Terje; Salbu, Brit; Teien, Hans-Christian

    2017-05-05

    Humic substances have a tendency to form complexes with metal ions in aquatic medium, impacting the metal mobility, decreasing bioavailability and toxicity. Ultraviolet-B (UV-B) radiation exposure degrades the humic substance, changes their molecular weight distribution and their metal binding capacity in aquatic medium. In this study, we experimented the effect of UV-B radiation on the uranium complexed with fulvic acids and humic acids in a soft water system at different pH, uranium concentrations and radiant exposure. The concentration and distribution of uranium in a complexed form were investigated by asymmetrical flow field-flow fractionation coupled to multi detection technique (AsFlFFF-UV-ICP-MS). The major concentration of uranium present in complexes was primarily associated with average and higher molecular weight fulvic and humic acids components. The concentration of uranium in a complexed form increased with increasing fulvic and humic acid concentrations as well as pH of the solution. The higher molecular weight fraction of uranium was degraded due to the UV-B exposure, transforming about 50% of the uranium-dissolved organic carbon complexes into low molecular weight uranium species in complex form with organic ligands and/or free form. The result also suggests AsFlFFF-UV-ICP-MS to be an important separation and detection technique for understanding the interaction of radionuclides with dissolved organic matter, tracking size distribution changes during degradation of organic complexes for understanding mobility, bioavailability and ecosystem transfer of radionuclides as well as metals. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Novel C-2 epimerization of aldoses promoted by nickel(II) diamine complexes, involving a stereospecific pinacol-type 1,2-carbon shift

    International Nuclear Information System (INIS)

    Tanase, Tomoaki; Shimizu, Fumihiko; Kuse, Manabu; Yano, Shigenobu; Hidai, Masanobu; Yoshikawa, Sadao

    1988-01-01

    The newly discovered C-2 epimerization of aldoses promoted by nickel(II) diamine complexes has been investigated in detail by using 13 C-enriched D-glucose, 13 C NMR spectroscopy, and EXAFS (extended x-ray absorption fine structure) analysis. Aldoses treated with nickel(II) diamine complexes (diamine = N,N,N'-trimethylethylenediamine (N,N,N'-Me 3 en), N,N,N',N'-tetramethylethylenediamine (N,N,N',N'-Me 4 en), etc.) in methanolic solutions were rapidly (60 degree C, 3-5 min) epimerized at C-2 to give equilibrium mixtures where the ratio of C-2 epimers shifts to the side of the naturally rare mannose-type aldoses (having the cis arrangement of C-2 and C-3 hydroxyl groups) compared with those in the thermodynamic equilibrium states. The epimerization product of D-[1- 13 C]glucose was exclusively D-[2- 13 C]mannose, demonstrating that the reaction involves a stereospecific 1,2-shift of the carbon skeleton resulting in inversion of configuration at C-2. Furthermore, the absorption and circular dichroism spectra of the reaction solutions indicated the presence of an intermediate nickel(II) complex containing both diamine and sugar components, which was directly revealed by EXAFS analysis to be a mononuclear nickel(II) complex having octahedral coordination geometry. All these observations strongly suggest that the C-2 epimerization proceeds through an intermediate mononuclear nickel(II) complex, where the carbinolamine-like adduct of aldose with diamine in an open-chain form is epimerized at C-2 by a stereospecific rearrangement of the carbon skeleton or a pinacol-type rearrangement involving a cyclic transition state. 44 refs., 5 figs., 4 tabs

  19. S center dot center dot center dot N chalcogen bonded complexes of carbon disulfide with diazines. Theoretical study

    Czech Academy of Sciences Publication Activity Database

    Zierkiewicz, W.; Fanfrlík, Jindřich; Michalczyk, M.; Michalska, D.; Hobza, Pavel

    2018-01-01

    Roč. 500, Jan 26 (2018), s. 37-44 ISSN 0301-0104 Institutional support: RVO:61388963 Keywords : chalcogen bond * carbon disulfide * diazines * DFT Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.767, year: 2016

  20. Five phosphonate operon gene products as components of a multi-subunit complex of the carbon-phosphorus lyase pathway

    DEFF Research Database (Denmark)

    Jochimsen, Bjarne; Lolle, Signe; McSorley, Fern R.

    2011-01-01

    Organophosphonate utilization by Escherichia coli requires the 14 cistrons of the phnCDEFGHIJKLMNOP operon, of which the carbon-phosphorus lyase has been postulated to consist of the seven polypeptides specified by phnG to phnM. A 5,660-bp DNA fragment encompassing phnGHIJKLM is cloned, followed...

  1. Reaction of carbon dioxide with a palladium–alkyl complex supported by a bis–NHC framework†

    Science.gov (United States)

    Ariyananda, Piyal W. G.; Yap, Glenn P. A.

    2012-01-01

    The reactivity of a dimethyl palladium complex supported by a dicarbene chelate (MDCMes)PdMe2 towards CO2 has been investigated. In the presence of trace H2O, this reaction yields the corresponding methyl bicarbonate complex (MDCMes)PdMe(O2COH), which goes on to give the corresponding κ2-carbonato complex upon crystallization (MDCMes)Pd(CO3). This chemistry, as well as related protonolysis by acetic acid was monitored by a combination of techniques including React-IR spectroscopy. PMID:22643651

  2. Reaction of carbon dioxide with a palladium-alkyl complex supported by a bis-NHC framework.

    Science.gov (United States)

    Ariyananda, Piyal W G; Yap, Glenn P A; Rosenthal, Joel

    2012-07-14

    The reactivity of a dimethyl palladium complex supported by a dicarbene chelate (MDC(Mes))PdMe(2) towards CO(2) has been investigated. In the presence of trace H(2)O, this reaction yields the corresponding methyl bicarbonate complex (MDC(Mes))PdMe(O(2)COH), which goes on to give the corresponding κ(2)-carbonato complex upon crystallization (MDC(Mes))Pd(CO(3)). This chemistry, as well as related protonolysis by acetic acid was monitored by a combination of techniques including React-IR spectroscopy.

  3. Synthesis, characterization and catalytic oxidation properties of multi-wall carbon nanotubes with a covalently attached copper(II) salen complex

    Science.gov (United States)

    Salavati-Niasari, Masoud; Bazarganipour, Mehdi

    2009-06-01

    Hydroxyl functionalized copper(II) Schiff-base, N,N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diaminecopper(II), [Cu((OH) 2-salen)], has been covalently anchored on modified MWCNTs. The new modified MWCNTs ([Cu((OH) 2-salen)]-MWCNTs) have been characterized by TEM, thermal analysis, XRD, XPS, UV-vis, DRS, FT-IR spectroscopy and elemental analysis. The modified copper(II) MWCNTs solid was used to affect the catalytic oxidation of ethylbenzene with tert-butylhydroperoxide as the oxidant at 333 K. The system is truly heterogeneous (no leaching observed) and reusable (no decrease in activity) in three consecutive runs. Acetophenone was the major product though small amounts of o- and p-hydroxyacetophenones were also formed revealing that C-H bond activation takes place both at benzylic and aromatic ring carbon atoms. Ring hydroxylation was more over the "neat" complexes than over the encapsulated complexes.

  4. Turn-on fluorescence sensor based on single-walled-carbon-nanohorn-peptide complex for the detection of thrombin.

    Science.gov (United States)

    Zhu, Shuyun; Liu, Zhongyuan; Hu, Lianzhe; Yuan, Yali; Xu, Guobao

    2012-12-14

    Proteases play a central role in several widespread diseases. Thus, there is a great need for the fast and sensitive detection of various proteolytic enzymes. Herein, we have developed a carbon nanotube (CNT)-based protease biosensing platform that uses peptides as a fluorescence probe for the first time. Single-walled carbon nanohorns (SWCNHs) and thrombin were used to demonstrate this detection strategy. SWCNHs can adsorb a fluorescein-based dye (FAM)-labeled peptide (FAM-pep) and quench the fluorescence of FAM. In contrast, thrombin can cleave FAM-pep on SWCNHs and recover the fluorescence of FAM, which allows the sensitive detection of thrombin. This biosensor has a high sensitivity and selectivity toward thrombin, with a detection limit of 100 pM. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Complex Permittivity of Polyaniline-Carbon Nanotube and Nanofibre Composites in the X-band. PMMA Composites

    National Research Council Canada - National Science Library

    Makeiff, Darren A; Huber, Trisha; Saville, Paul

    2005-01-01

    ... the complex permittivity from transmission-reflection waveguide measurements in the X-band (8-12 GHz). PMMA composites containing PAni-MWNT or PAni-CNFs poorer, while PMMA composites containing PAni and MWNT mixed ex situ...

  6. Effect of the porous structure of activated carbon on the adsorption kinetics of gold(I) cyanide complex

    Science.gov (United States)

    Ibragimova, P. I.; Grebennikov, S. F.; Gur'yanov, V. V.; Fedyukevich, V. A.; Vorob'ev-Desyatovskii, N. V.

    2014-06-01

    The effect the porous structure of activated carbons obtained from furfural and coconut shells has on the kinetics of [Au(CN)2]- ion adsorption is studied. Effective diffusion coefficients for [Au(CN)2]- anions in transport and adsorbing pores and mass transfer coefficients in a transport system of the pores and in microporous zones are calculated using the statistical moments of the kinetic curve.

  7. Determination of formation constants of hydroxo carbonate complexes of Pr3+ in 2M NaCl at 303 K

    International Nuclear Information System (INIS)

    Lopez G, H.D.

    1996-01-01

    The hydrolysis of Praseodymium III in 2M sodium chloride at 303 K was studied. Two methods were used: pH titration followed by a computational refinement and solvent extraction in the presence of a competitive ligand. The hydrolysis constants obtained by pH titration were: log β 1,H = -7.68 ± 0.07, log β 1,2H = -15.10 ± 0.03, and β 1,3H -23.8 ± 0.04. The stability constants of Praseodymium carbonates were determined by pH titration as well and were: log β 1,CO3 2- = 5.94 ± 0.08 and log β 1,2CO3 2- = 11.15 ± 0.15. Praseodymium carbonate species were taken into consideration for calculating the first hydrolysis constants by the solvent extraction method and the value obtained was: log β 1,H = -7.69 ± 0.27. The values for log β 1,H attained by both methods are the same. The species-distribution diagram was obtained from the stability constants of Praseodymium carbonates and hydrolysis products in the conditions of the present work. (Author)

  8. Complexing Agents on Carbon Content and Lithium Storage Capacity of LiFePO4/C Cathode Synthesized via Sol-Gel Approach

    Directory of Open Access Journals (Sweden)

    C. Guan

    2016-01-01

    Full Text Available Olivine-structured LiFePO4 faces its intrinsic challenges in terms of poor electrical conductivity and lithium-ion diffusion capability for application to lithium-ion batteries. Cost-effective sol-gel approach is advantageous to in situ synthesize carbon-coated LiFePO4 (LiFePO4/C which can not only improve electronic conductivity but also constrain particle size to nanometer scale. In this study, the key parameter is focused on the choice and amount of chelating agents in this synthesis route. It was found that stability of complexing compounds has significant impacts on the carbon contents and electrochemical properties of the products. At the favorable choice of precursors, composition, and synthesis conditions, nanocrystalline LiFePO4/C materials with appropriate amount of carbon coating were successfully obtained. A reversible capacity of 162 mAh/g was achieved at 0.2C rate, in addition to good discharge rate capability.

  9. Spatial complexities in aboveground carbon stocks of a semi-arid mangrove community: A remote sensing height-biomass-carbon approach

    Science.gov (United States)

    Hickey, S. M.; Callow, N. J.; Phinn, S.; Lovelock, C. E.; Duarte, C. M.

    2018-01-01

    Mangroves are integral to ecosystem services provided by the coastal zone, in particular carbon (C) sequestration and storage. Allometric relationships linking mangrove height to estimated biomass and C stocks have been developed from field sampling, while various forms of remote sensing has been used to map vegetation height and biomass. Here we combine both these approaches to investigate spatial patterns in living biomass of mangrove forests in a small area of mangrove in north-west Australia. This study used LiDAR data and Landsat 8 OLI (Operational Land Imager) with allometric equations to derive mangrove height, biomass, and C stock estimates. We estimated the study site, Mangrove Bay, a semi-arid site in north-western Australia, contained 70 Mg ha-1 biomass and 45 Mg C ha-1 organic C, with total stocks of 2417 Mg biomass and 778 Mg organic C. Using spatial statistics to identify the scale of clustering of mangrove pixels, we found that living biomass and C stock declined with increasing distance from hydrological features (creek entrance: 0-150 m; y = -0.00041x + 0.9613, R2 = 0.96; 150-770 m; y = -0.0008x + 1.6808, R2 = 0.73; lagoon: y = -0.0041x + 3.7943, R2 = 0.78). Our results illustrate a set pattern of living C distribution within the mangrove forest, and then highlight the role hydrologic features play in determining C stock distribution in the arid zone.

  10. Effect of complex training on carbon monoxide, cardiorespiratory function, and body mass among college students at the initial stage of stopping smoking.

    Science.gov (United States)

    Kim, Seungsuk

    2017-08-01

    [Purpose] This study aimed to analyze the effects of complex training on carbon monoxide, cardiorespiratory function, and body mass among college students with the highest smoking rate among all age group. [Subjects and Methods] A total of 40 college students voluntarily participated in this study. All subjects smoked and were randomly divided into two groups: the experimental group (N=20) and the control group (N=20). The experimental group underwent complex training (30 min of training five times a week for 12 weeks) while the control group did not participate in such training. The complex training consisted of two parts: aerobic exercise (walking and running) and resistance exercise (weight training). [Results] Two-way ANOVA with repeated measures revealed significant interactions among CO, VO2max, HRmax, VEmax, body fat, and skeletal muscle mass, indicating that the changes were significantly different among groups. [Conclusion] A 12 week of complex physical exercise program would be an effective way to support a stop-smoking campaign as it quickly eliminates CO from the body and improves cardiorespiratory function and body condition.

  11. Thermodynamic description of Tc(iv) solubility and carbonate complexation in alkaline NaHCO3-Na2CO3-NaCl systems.

    Science.gov (United States)

    Baumann, A; Yalçıntaş, E; Gaona, X; Polly, R; Dardenne, K; Prüßmann, T; Rothe, J; Altmaier, M; Geckeis, H

    2018-03-28

    The solubility of 99 Tc(iv) was investigated in dilute to concentrated carbonate solutions (0.01 M ≤ C tot ≤ 1.0 M, with C tot = [HCO 3 - ] + [CO 3 2- ]) under systematic variation of ionic strength (I = 0.3-5.0 M NaHCO 3 -Na 2 CO 3 -NaCl-NaOH) and pH m (-log[H + ] = 8.5-14.5). Strongly reducing conditions (pe + pH m ≈ 2) were set with Sn(ii). Carbonate enhances the solubility of Tc(iv) in alkaline conditions by up to 3.5 log 10 -units compared to carbonate-free systems. Solvent extraction and XANES confirmed that Tc was kept as +IV during the timeframe of the experiments (≤ 650 days). Solid phase characterization performed by XAFS, XRD, SEM-EDS, chemical analysis and TG-DTA confirmed that TcO 2 ·0.6H 2 O(am) controls the solubility of Tc(iv) under the conditions investigated. Slope analysis of the solubility data in combination with solid/aqueous phase characterization and DFT calculations indicate the predominance of the species Tc(OH) 3 CO 3 - at pH m ≤ 11 and C tot ≥ 0.01 M, for which thermodynamic and activity models are derived. Solubility data obtained above pH m ≈ 11 indicates the formation of previously unreported Tc(iv)-carbonate species, possibly Tc(OH) 4 CO 3 2- , although the likely formation of additional complexes prevents deriving a thermodynamic model valid for this pH m -region. This work provides the most comprehensive thermodynamic dataset available for the system Tc 4+ -Na + -Cl - -OH - -HCO 3 - -CO 3 2- -H 2 O(l) valid under a range of conditions relevant for nuclear waste disposal.

  12. Spatial complexities in aboveground carbon stocks of a semi-arid mangrove community: A remote sensing height-biomass-carbon approach

    KAUST Repository

    Hickey, S.M.

    2017-11-10

    Mangroves are integral to ecosystem services provided by the coastal zone, in particular carbon (C) sequestration and storage. Allometric relationships linking mangrove height to estimated biomass and C stocks have been developed from field sampling, while various forms of remote sensing has been used to map vegetation height and biomass. Here we combine both these approaches to investigate spatial patterns in living biomass of mangrove forests in a small area of mangrove in north-west Australia. This study used LiDAR data and Landsat 8 OLI (Operational Land Imager) with allometric equations to derive mangrove height, biomass, and C stock estimates. We estimated the study site, Mangrove Bay, a semi-arid site in north-western Australia, contained 70 Mg ha−1 biomass and 45 Mg C ha−1 organic C, with total stocks of 2417 Mg biomass and 778 Mg organic C. Using spatial statistics to identify the scale of clustering of mangrove pixels, we found that living biomass and C stock declined with increasing distance from hydrological features (creek entrance: 0–150 m; y = −0.00041x + 0.9613, R2 = 0.96; 150–770 m; y = −0.0008x + 1.6808, R2 = 0.73; lagoon: y = −0.0041x + 3.7943, R2 = 0.78). Our results illustrate a set pattern of living C distribution within the mangrove forest, and then highlight the role hydrologic features play in determining C stock distribution in arid zone.

  13. Carbon dioxide is tightly bound in the [Co(Pyridine)(CO{sub 2})]{sup −} anionic complex

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Jacob D.; Buytendyk, Allyson M.; Zhang, Xinxing; Bowen, Kit H., E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kim, Seong K. [Department of Chemistry, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-11-14

    The [Co(Pyridine)(CO{sub 2})]{sup −} anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO{sub 2} binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO{sub 2})]{sup −} in which a central cobalt atom is bound to pyridine and CO{sub 2} moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO{sub 2} to be bound within the anionic complex by 1.4 eV.

  14. Carbon-oxygen log applications in complex reservoir evaluation by neutron interactions from (D,T) accelerators

    International Nuclear Information System (INIS)

    Lochmann, M.J.; Berg, L.O.; Ivey, R.C.

    1983-01-01

    Granite Wash reservoirs in Oklahoma, Texas, Colorado and New Mexico have proven to be effective commercial producers of hydrocarbons. Substantial drilling activity continues to penetrate this formation either as a primary or secondary objective. A new technique to provide additional lithologic data to engineers and geologists will yield significant benefits in the evaluation and treatment of these reservoirs. This information can be obtained by data available from spectrum analysis through the use of tools such as the Carbon/Oxygen Log, Spectralog and NGS

  15. Complex Physiological Response of Norway Spruce to Atmospheric Pollution – Decreased Carbon Isotope Discrimination and Unchanged Tree Biomass Increment

    Science.gov (United States)

    Čada, Vojtěch; Šantrůčková, Hana; Šantrůček, Jiří; Kubištová, Lenka; Seedre, Meelis; Svoboda, Miroslav

    2016-01-01

    Atmospheric pollution critically affects forest ecosystems around the world by directly impacting the assimilation apparatus of trees and indirectly by altering soil conditions, which subsequently also leads to changes in carbon cycling. To evaluate the extent of the physiological effect of moderate level sulfate and reactive nitrogen acidic deposition, we performed a retrospective dendrochronological analysis of several physiological parameters derived from periodic measurements of carbon stable isotope composition (13C discrimination, intercellular CO2 concentration and intrinsic water use efficiency) and annual diameter increments (tree biomass increment, its inter-annual variability and correlation with temperature, cloud cover, precipitation and Palmer drought severity index). The analysis was performed in two mountain Norway spruce (Picea abies) stands of the Bohemian Forest (Czech Republic, central Europe), where moderate levels of pollution peaked in the 1970s and 1980s and no evident impact on tree growth or link to mortality has been reported. The significant influence of pollution on trees was expressed most sensitively by a 1.88‰ reduction of carbon isotope discrimination (Δ13C). The effects of atmospheric pollution interacted with increasing atmospheric CO2 concentration and temperature. As a result, we observed no change in intercellular CO2 concentrations (Ci), an abrupt increase in water use efficiency (iWUE) and no change in biomass increment, which could also partly result from changes in carbon partitioning (e.g., from below- to above-ground). The biomass increment was significantly related to Δ13C on an individual tree level, but the relationship was lost during the pollution period. We suggest that this was caused by a shift from the dominant influence of the photosynthetic rate to stomatal conductance on Δ13C during the pollution period. Using biomass increment-climate correlation analyses, we did not identify any clear pollution

  16. Complex Physiological Response of Norway Spruce to Atmospheric Pollution - Decreased Carbon Isotope Discrimination and Unchanged Tree Biomass Increment.

    Science.gov (United States)

    Čada, Vojtěch; Šantrůčková, Hana; Šantrůček, Jiří; Kubištová, Lenka; Seedre, Meelis; Svoboda, Miroslav

    2016-01-01

    Atmospheric pollution critically affects forest ecosystems around the world by directly impacting the assimilation apparatus of trees and indirectly by altering soil conditions, which subsequently also leads to changes in carbon cycling. To evaluate the extent of the physiological effect of moderate level sulfate and reactive nitrogen acidic deposition, we performed a retrospective dendrochronological analysis of several physiological parameters derived from periodic measurements of carbon stable isotope composition ((13)C discrimination, intercellular CO2 concentration and intrinsic water use efficiency) and annual diameter increments (tree biomass increment, its inter-annual variability and correlation with temperature, cloud cover, precipitation and Palmer drought severity index). The analysis was performed in two mountain Norway spruce (Picea abies) stands of the Bohemian Forest (Czech Republic, central Europe), where moderate levels of pollution peaked in the 1970s and 1980s and no evident impact on tree growth or link to mortality has been reported. The significant influence of pollution on trees was expressed most sensitively by a 1.88‰ reduction of carbon isotope discrimination (Δ(13)C). The effects of atmospheric pollution interacted with increasing atmospheric CO2 concentration and temperature. As a result, we observed no change in intercellular CO2 concentrations (Ci), an abrupt increase in water use efficiency (iWUE) and no change in biomass increment, which could also partly result from changes in carbon partitioning (e.g., from below- to above-ground). The biomass increment was significantly related to Δ(13)C on an individual tree level, but the relationship was lost during the pollution period. We suggest that this was caused by a shift from the dominant influence of the photosynthetic rate to stomatal conductance on Δ(13)C during the pollution period. Using biomass increment-climate correlation analyses, we did not identify any clear pollution

  17. Constraining Silicate Weathering Processes in an Active Volcanic Complex: Implications for the Long-term Carbon Cycle

    Science.gov (United States)

    Washington, K.; West, A. J.; Hartmann, J.; Amann, T.; Hosono, T.; Ide, K.

    2017-12-01

    While analyzing geochemical archives and carbon cycle modelling can further our understanding of the role of silicate weathering as a sink in the long-term carbon cycle, it is necessary to study modern weathering processes to inform these efforts. A recent compilation of data from rivers draining basaltic catchments estimates that rock weathering in active volcanic fields (AVFs) consumes atmospheric CO2 approximately three times faster than in inactive volcanic fields (IVFs), suggesting that the eruption and subsequent weathering of large igneous provinces likely played a major role in the carbon cycle in the geologic past [1]. The study demonstrates a significant correlation between catchment mean annual temperature (MAT) and atmospheric CO2 consumption rate for IVFs. However CO2 consumption due to weathering of AVFs is not correlated with MAT as the relationship is complicated by variability in hydrothermal fluxes, reactive surface area, and groundwater flow paths. To investigate the controls on weathering processes in AVFs, we present data for dissolved and solid weathering products from Mount Aso Caldera, Japan. Aso Caldera is an ideal site for studying the how the chemistry of rivers draining an AVF is impacted by high-temperature water/rock interactions, volcanic ash weathering, and varied groundwater flow paths and residence times. Samples were collected over five field seasons from two rivers and their tributaries, cold groundwater springs, and thermal springs. These samples capture the region's temperature and precipitation seasonality. Solid samples of unaltered volcanic rocks, hydrothermally-altered materials, volcanic ash, a soil profile, and suspended and bedload river sediments were also collected. The hydrochemistry of dissolved phases were analyzed at the University of Hamburg, while the mineralogy and geochemical compositions of solid phases were analyzed at the Natural History Museum of Los Angeles. This work will be discussed in the context of

  18. Development and evaluation of pH-responsive single-walled carbon nanotube-doxorubicin complexes in cancer cells

    Directory of Open Access Journals (Sweden)

    Gu YJ

    2011-11-01

    Full Text Available Yan-Juan Gu1,2,*, Jinping Cheng2,*, Jiefu Jin3, Shuk Han Cheng2, Wing-Tak Wong11Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, 2Department of Biology and Chemistry, The City University of Hong Kong, 3Department of Chemistry, The University of Hong Kong, Hong Kong, China*These authors contributed equally to this workAbstract: Single-walled carbon nanotubes (SWNTs have been identified as an efficient drug carrier. Here a controlled drug-delivery system based on SWNTs coated with doxorubicin (DOX through hydrazone bonds was developed, because the hydrazone bond is more sensitive to tumor microenvironments than other covalent linkers. The SWNTs were firstly stabilized with polyethylene glycol (H2N-PEG-NH2. Hydrazinobenzoic acid (HBA was then covalently attached on SWNTs via carbodiimide-activated coupling reaction to form hydrazine-modified SWNTs. The anticancer drug DOX was conjugated to the HBA segments of SWNT using hydrazine as the linker. The resulting hydrazone bonds formed between the DOX molecules and the HBA segments of SWNTs are acid cleavable, thereby providing a strong pH-responsive drug release, which may facilitate effective DOX release near the acidic tumor microenvironment and thus reduce its overall systemic toxicity. The DOX-loaded SWNTs were efficiently taken up by HepG2 tumor cells, and DOX was released intracellularly, as revealed by MTT assay and confocal microscope observations. Compared with SWNT-DOX conjugate formed by supramolecular interaction, the SWNT-HBA-DOX featured high weight loading and prolonged release of DOX, and thus improved its cytotoxicity against cancer cells. This study suggests that while SWNTs have great potential as a drug carrier, the efficient formulation strategy requires further study.Keywords: carbon nanotubes, drug delivery, controlled release, SWNTs

  19. Study of copper and purine-copper complexes on modified carbon electrodes by cyclic and elimination voltammetry

    Czech Academy of Sciences Publication Activity Database

    Trnková, L.; Zerzánková, L.; Dyčka, F.; Mikelová, R.; Jelen, František

    2008-01-01

    Roč. 8, č. 1 (2008), s. 429-444 ISSN 1424-8220 R&D Projects: GA AV ČR(CZ) IAA100040602; GA AV ČR(CZ) IAA400040804 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : copper-purine complexes * paraffin-impregnated graphite electrode * mercury-film electrode Subject RIV: BO - Biophysics Impact factor: 1.870, year: 2008

  20. Extraction of superoxide dismutase, catalase, and carbonic anhydrase from stroma-free red blood cell hemolysate for the preparation of the nanobiotechnological complex of polyhemoglobin-superoxide dismutase-catalase-carbonic anhydrase.

    Science.gov (United States)

    Guo, C; Gynn, M; Chang, T M S

    2015-06-01

    We report a novel method to simultaneously extract superoxide dismutase (SOD), catalase (CAT), and carbonic anhydrase (CA) from the same sample of red blood cells (RBCs). This avoids the need to use expensive commercial enzymes, thus enabling a cost-effective process for large-scale production of a nanobiotechnological polyHb-SOD-CAT-CA complex, with enhancement of all three red blood cell functions. An optimal concentration of phosphate buffer for ethanol-chloroform treatment results in good recovery of CAT, SOD, and CA after extraction. Different concentrations of the enzymes can be used to enhance the activity of polyHb-SOD-CAT-CA to 2, 4, or 6 times that of RBC.

  1. Improving the Spatial Prediction of Soil Organic Carbon Stocks in a Complex Tropical Mountain Landscape by Methodological Specifications in Machine Learning Approaches.

    Directory of Open Access Journals (Sweden)

    Mareike Ließ

    Full Text Available Tropical forests are significant carbon sinks and their soils' carbon storage potential is immense. However, little is known about the soil organic carbon (SOC stocks of tropical mountain areas whose complex soil-landscape and difficult accessibility pose a challenge to spatial analysis. The choice of methodology for spatial prediction is of high importance to improve the expected poor model results in case of low predictor-response correlations. Four aspects were considered to improve model performance in predicting SOC stocks of the organic layer of a tropical mountain forest landscape: Different spatial predictor settings, predictor selection strategies, various machine learning algorithms and model tuning. Five machine learning algorithms: random forests, artificial neural networks, multivariate adaptive regression splines, boosted regression trees and support vector machines were trained and tuned to predict SOC stocks from predictors derived from a digital elevation model and satellite image. Topographical predictors were calculated with a GIS search radius of 45 to 615 m. Finally, three predictor selection strategies were applied to the total set of 236 predictors. All machine learning algorithms-including the model tuning and predictor selection-were compared via five repetitions of a tenfold cross-validation. The boosted regression tree algorithm resulted in the overall best model. SOC stocks ranged between 0.2 to 17.7 kg m-2, displaying a huge variability with diffuse insolation and curvatures of different scale guiding the spatial pattern. Predictor selection and model tuning improved the models' predictive performance in all five machine learning algorithms. The rather low number of selected predictors favours forward compared to backward selection procedures. Choosing predictors due to their indiviual performance was vanquished by the two procedures which accounted for predictor interaction.

  2. Improving the Spatial Prediction of Soil Organic Carbon Stocks in a Complex Tropical Mountain Landscape by Methodological Specifications in Machine Learning Approaches.

    Science.gov (United States)

    Ließ, Mareike; Schmidt, Johannes; Glaser, Bruno

    2016-01-01

    Tropical forests are significant carbon sinks and their soils' carbon storage potential is immense. However, little is known about the soil organic carbon (SOC) stocks of tropical mountain areas whose complex soil-landscape and difficult accessibility pose a challenge to spatial analysis. The choice of methodology for spatial prediction is of high importance to improve the expected poor model results in case of low predictor-response correlations. Four aspects were considered to improve model performance in predicting SOC stocks of the organic layer of a tropical mountain forest landscape: Different spatial predictor settings, predictor selection strategies, various machine learning algorithms and model tuning. Five machine learning algorithms: random forests, artificial neural networks, multivariate adaptive regression splines, boosted regression trees and support vector machines were trained and tuned to predict SOC stocks from predictors derived from a digital elevation model and satellite image. Topographical predictors were calculated with a GIS search radius of 45 to 615 m. Finally, three predictor selection strategies were applied to the total set of 236 predictors. All machine learning algorithms-including the model tuning and predictor selection-were compared via five repetitions of a tenfold cross-validation. The boosted regression tree algorithm resulted in the overall best model. SOC stocks ranged between 0.2 to 17.7 kg m-2, displaying a huge variability with diffuse insolation and curvatures of different scale guiding the spatial pattern. Predictor selection and model tuning improved the models' predictive performance in all five machine learning algorithms. The rather low number of selected predictors favours forward compared to backward selection procedures. Choosing predictors due to their indiviual performance was vanquished by the two procedures which accounted for predictor interaction.

  3. Electrocatalytic determination of L-ascorbic acid by modified glassy carbon with Ni(Me2(CH3CO)2[14]tetraenoN4) complex.

    Science.gov (United States)

    Khorasani-Motlagh, Mozhgan; Noroozifar, Meissam

    2003-12-01

    A novel modified glassy carbon electrode containing Ni(Me2(CH3CO)2[14]tetraenoN4) complex was used as an electrocatalytic sensor for the determination of L-ascorbic acid in pH = 6.6. The peak potential shifted to negative by 205 mV compared with that for a bare electrode in cyclic voltammograms. The calibration curve was linear up to 6.2 x 10(-3) M with a detection limit 3.1 x 10(-7) M and an RSD% better than 2.47%. This newly modified electrode was applied to commercial pharmaceutical tablets, injections and foods. The obtained results were identical to those obtained by the classical 2,6-dichlorophenolindophenol method.

  4. A carbon-supported copper complex of 3,5-diamino-1,2,4-triazole as a cathode catalyst for alkaline fuel cell applications.

    Science.gov (United States)

    Brushett, Fikile R; Thorum, Matthew S; Lioutas, Nicholas S; Naughton, Matthew S; Tornow, Claire; Jhong, Huei-Ru Molly; Gewirth, Andrew A; Kenis, Paul J A

    2010-09-08

    The performance of a novel carbon-supported copper complex of 3,5-diamino-1,2,4-triazole (Cu-tri/C) is investigated as a cathode material using an alkaline microfluidic H(2)/O(2) fuel cell. The absolute Cu-tri/C cathode performance is comparable to that of a Pt/C cathode. Furthermore, at a commercially relevant potential, the measured mass activity of an unoptimized Cu-tri/C-based cathode was significantly greater than that of similar Pt/C- and Ag/C-based cathodes. Accelerated cathode durability studies suggested multiple degradation regimes at various time scales. Further enhancements in performance and durability may be realized by optimizing catalyst and electrode preparation procedures.

  5. Molecular Insights into the Complex Relationship between Capacitance and Pore Morphology in Nanoporous Carbon-based Supercapacitors.

    Science.gov (United States)

    Pak, Alexander J; Hwang, Gyeong S

    2016-12-21

    Electrochemical double layer capacitors, or supercapacitors, are high-power energy storage devices that consist of large surface area electrodes (filled with electrolyte) to accommodate ion packing in accordance with classical electric double layer (EDL) theory. Nanoporous carbons (NPCs) have recently emerged as a class of electrode materials with the potential to dramatically improve the capacitance of these devices by leveraging ion confinement. However, the molecular mechanisms underlying such enhancements are a clear departure from EDL theory and remain an open question. In this paper, we present the concept of ion reorganization kinetics during charge/discharge cycles, especially within highly confining subnanometer pores, which necessarily dictates the capacitance. Our molecular dynamics voltammetric simulations of ionic liquid immersed in NPC electrodes (of varying pore size distributions) demonstrate that the most efficient ion migration, and thereby largest capacitance, is facilitated by nonuniformity of shape (e.g., from cylindrical to slitlike) along nanopore channels. On the basis of this understanding, we propose that a new structural descriptor, coined as the pore shape factor, can provide a new avenue for materials optimization. These findings also present a framework to understand and evaluate ion migration kinetics within charged nanoporous materials.

  6. Strategies for efficiently selecting PHA producing mixed microbial cultures using complex feedstocks: Feast and famine regime and uncoupled carbon and nitrogen availabilities.

    Science.gov (United States)

    Oliveira, Catarina S S; Silva, Carlos E; Carvalho, Gilda; Reis, Maria A

    2017-07-25

    Production of polyhydroxyalkanoates (PHAs) by open mixed microbial cultures (MMCs) has been attracting increasing interest as an alternative technology to PHA production by pure cultures, due to the potential for lower costs associated with the use of open systems (eliminating the requirement for sterile conditions) and the utilisation of cheap feedstock (industrial and agricultural wastes). Such technology relies on the efficient selection of an MMC enriched in PHA-accumulating organisms. Fermented cheese whey, a protein-rich complex feedstock, has been used previously to produce PHA using the feast and famine regime for selection of PHA accumulating cultures. While this selection strategy was found efficient when operated at relatively low organic loading rate (OLR, 2g-CODL -1 d -1 ), great instability and low selection efficiency of PHA accumulating organisms were observed when higher OLR (ca. 6g-CODL -1 d -1 ) was applied. High organic loading is desirable as a means to enhance PHA productivity. In the present study, a new selection strategy was tested with the aim of improving selection for high OLR. It was based on uncoupling carbon and nitrogen supply and was implemented and compared with the conventional feast and famine strategy. For this, two selection reactors were fed with fermented cheese whey applying an OLR of ca. 8.5g-CODL -1 (with 3.8g-CODL -1 resulting from organic acids and ethanol), and operated in parallel under similar conditions, except for the timing of nitrogen supplementation. Whereas in the conventional strategy nitrogen and carbon substrates were added simultaneously at the beginning of the cycle, in the uncoupled substrates strategy, nitrogen addition was delayed to the end of the feast phase (i.e. after exogenous carbon was exhausted). The two different strategies selected different PHA-storing microbial communities, dominated by Corynebacterium and a Xantomonadaceae, respectively with the conventional and the new approaches. The new

  7. Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex

    International Nuclear Information System (INIS)

    Dung, Le Thi Kim; Imai, Tomoki; Tomioka, Osamu; Nakashima, Mikio; Takahashi, Kuniaki; Meguro, Yoshihiro

    2006-01-01

    The supercritical fluid extraction (SFE) method using CO 2 as a medium with an extractant of HNO 3 -tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO 2 . It was thus demonstrated that the SFE method using CO 2 is useful as a pretreatment method for the analysis of uranium in ores. (author)

  8. Robust binding between carbon nitride nanosheets and a binuclear ruthenium(II) complex enabling durable, selective CO{sub 2} reduction under visible light in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Kuriki, Ryo; Ishitani, Osamu; Maeda, Kazuhiko [Department of Chemistry, School of Science, Tokyo Institute of Technology (Japan); Yamamoto, Muneaki; Yoshida, Tomoko [Advanced Research Institute for Natural Science and Technology, Osaka City University (Japan); Higuchi, Kimitaka; Yamamoto, Yuta; Akatsuka, Masato; Yagi, Shinya [Institute of Materials and Systems for Sustainability, Nagoya University (Japan); Lu, Daling [Suzukakedai Materials Analysis Division, Technical Department, Tokyo Institute of Technology, Yokohama (Japan)

    2017-04-18

    Carbon nitride nanosheets (NS-C{sub 3}N{sub 4}) were found to undergo robust binding with a binuclear ruthenium(II) complex (RuRu') even in basic aqueous solution. A hybrid material consisting of NS-C{sub 3}N{sub 4} (further modified with nanoparticulate Ag) and RuRu' promoted the photocatalytic reduction of CO{sub 2} to formate in aqueous media, in conjunction with high selectivity (approximately 98 %) and a good turnover number (>2000 with respect to the loaded Ru complex). These represent the highest values yet reported for a powder-based photocatalytic system during CO{sub 2} reduction under visible light in an aqueous environment. We also assessed the desorption of RuRu' from the Ag/C{sub 3}N{sub 4} surface, a factor that can contribute to a loss of activity. It was determined that desorption is not induced by salt additives, pH changes, or photoirradiation, which partly explains the high photocatalytic performance of this material. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Formation of molecular complexes of salicylic acid, acetylsalicylic acid, and methyl salicylate in a mixture of supercritical carbon dioxide with a polar cosolvent

    Science.gov (United States)

    Petrenko, V. E.; Antipova, M. L.; Gurina, D. L.; Odintsova, E. G.

    2015-08-01

    The solvate structures formed by salicylic acid, acetylsalicylic acid, and methyl salicylate in supercritical (SC) carbon dioxide with a polar cosolvent (methanol, 0.03 mole fractions) at a density of 0.7 g/cm3 and a temperature of 318 K were studied by the molecular dynamics method. Salicylic and acetylsalicylic acids were found to form highly stable hydrogen-bonded complexes with methanol via the hydrogen atom of the carboxyl group. For methyl salicylate in which the carboxyl hydrogen is substituted by a methyl radical, the formation of stable hydrogen bonds with methanol was not revealed. The contribution of other functional groups of the solute to the interactions with the cosolvent was much smaller. An analysis of correlations between the obtained data and the literature data on the cosolvent effect on the solubility of the compounds in SC CO2 showed that the dissolving ability of SC CO2 with respect to a polar organic substance in the presence of a cosolvent increased only when stable hydrogen-bonded complexes are formed between this substance and the cosolvent.

  10. Planting increases the abundance and structure complexity of soil core functional genes relevant to carbon and nitrogen cycling.

    Science.gov (United States)

    Wang, Feng; Liang, Yuting; Jiang, Yuji; Yang, Yunfeng; Xue, Kai; Xiong, Jinbo; Zhou, Jizhong; Sun, Bo

    2015-09-23

    Plants have an important impact on soil microbial communities and their functions. However, how plants determine the microbial composition and network interactions is still poorly understood. During a four-year field experiment, we investigated the functional gene composition of three types of soils (Phaeozem, Cambisols and Acrisol) under maize planting and bare fallow regimes located in cold temperate, warm temperate and subtropical regions, respectively. The core genes were identified using high-throughput functional gene microarray (GeoChip 3.0), and functional molecular ecological networks (fMENs) were subsequently developed with the random matrix theory (RMT)-based conceptual framework. Our results demonstrated that planting significantly (P soils and 83.5% of microbial alpha-diversity can be explained by the plant factor. Moreover, planting had significant impacts on the microbial community structure and the network interactions of the microbial communities. The calculated network complexity was higher under maize planting than under bare fallow regimes. The increase of the functional genes led to an increase in both soil respiration and nitrification potential with maize planting, indicating that changes in the soil microbial communities and network interactions influenced ecological functioning.

  11. Influence of the competition of anions (hydroxides, carbonates) on the complexation of trivalent lanthanides by natural organic matter: case of humic substances

    International Nuclear Information System (INIS)

    Kouhail, Yasmine

    2016-01-01

    The aim of this study is to acquire and refine complexation data for understanding the fate of lanthanides in the environment where the concentrations of organic matter are highly variable. This study is focusing on both the description and understanding of the interactions between the europium(III) and a Suwannee River fulvic acid (SRFA) as a representative of humic substances (HS), and the influence of major anions present in natural waters, i.e. hydroxides and carbonates ions, in these interactions. To understand the ternary systems Eu-OH-SRFA and EU-CO_3-SRFA, Eu-SRFA and EU-CO_3 binary systems are first investigated by time-resolved luminescence spectroscopy (TRLS) for wide ranges of pH, ionic strength, Eu(III), SRFA and CO_3 concentrations. This study shows that the structures of humic substances are influenced by the presence of Eu(III). Interaction constants are determined for the Eu-SRFA binary system and are used for the understanding of the EU-CO_3-SRFA ternary system. EU-CO_3-SRF A ternary complexes are highlighted by SLRT, and an interaction constant has also been proposed in the frame of the NICA-Donnan model. Variations in size of EuSRFA complexes as a function of europium and SRFA concentrations are presented, and the impact of these variations on NICA-Donnan parameters is investigated. The results of this work are challenging modeling concepts of metal-HS interactions at various HS concentrations, in particular for the consideration of electrostatic effects. (author) [fr

  12. Thermodynamic and kinetic studies of the equilibration reaction between the sulfur and carbon bonded forms of a cobalt(III) complex with the ligands 1,4,7-triazycyclononane and 1,4-diaza-7-thiacyclodecane

    DEFF Research Database (Denmark)

    Song, Y.S.; Becker, J.; Kofod, Pauli

    1996-01-01

    The new cyclic thioether 1,4-diaza-7-thiacyclodecane, dathicd, has been synthesized and used for the prepn. of the sulfur- and carbon-bonded cobalt(III) complexes: [Co(tacn)(S-dathicd)]Cl3.5H2O and [Co(tacn)(C-dathicd)](ClO4)2 (tacn, 1,4,7-triazacyclononane; C-dathicd, 1,4-diamino-7-thiacyclodecan......-sulfur complex to form the alkyl complex gave 100% loss of deuterium. It is concluded that the labile methylene proton is bound to the carbon atom which in the alkyl complex is bound to cobalt(III). From the kinetic data it is estd. that the carbanion reacts with water 270 times faster than it is captured...

  13. Solubility of AnO{sub 2}.xH{sub 2}O(am) in carbonate solution and formation of ternary An(IV) hydroxide-carbonate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Neck, V.; Altmaier, M. [Institut fuer Nukleare Entsorgung, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe (Germany); Fanghaenel, Th. [Institut fuer Nukleare Entsorgung, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe (Germany); Physikalisch-Chemisches Institut, Ruprecht-Karls-Universitaet, Im Neuenheimer Feld 253, D-69120 Heidelberg (Germany)

    2005-07-01

    Full text of publication follows: The solubility of amorphous An(IV) hydroxides or hydrous oxides is studied with Th(IV) as a redox-stable surrogate for the other tetravalent actinides at I = 0.1 - 4 M (NaHCO{sub 3}-Na{sub 2}CO{sub 3}-NaOHNaCl) and 22 deg. C. Several series of closed system experiments at total carbonate concentrations of C{sub tot} = [HCO{sub 3}{sup -}] + [CO{sub 3}{sup 2-}] = 0.02 and 0.1 M in the range pH{sub c} = 8 - 13 and in Na{sub 2}CO{sub 3}-NaOH mixtures are performed with Th(IV) and additionally with Pu(IV). In our recent study with Th(IV) at I = 0.5 M [1], the simultaneous evaluation of solubility data at widely varied pH and carbonate concentrations has shown that Th(OH)(CO{sub 3}){sub 4}{sup 5-}, Th(OH){sub 2}(CO{sub 3}){sub 2}{sup 2-} and Th(OH){sub 4}(CO{sub 3}){sup 2-} are the most important ternary complexes. The present results at I = 0.1 - 4 M are used to describe the ionic strength dependence of the equilibrium constants log K{sub s,1yz} = log K{sub sp} + log {beta}{sub 1yz} for the reactions An(OH){sub 4}(am) + z CO{sub 3}{sup 2-} {r_reversible} An(OH){sub y}(CO{sub 3}){sub z}{sup 4-y-2z} + (4-y) OH{sup -}. Using the evaluated ion interaction (SIT) coefficients, available solubility data for U(IV), Np(IV) and Pu(IV) in wide ranges of pH, carbonate concentration and ionic strength, in particular apparently conflicting literature data for Np(IV) [2, 3] and Pu(IV) [2, 4], can be described with a consistent set of equilibrium constants. The predominant complexes An(OH){sub y}(CO{sub 3}){sub z}{sup 4-y-2z} and their formation constants log {beta}{sup 0}{sub 1yz} show pronounced analogies and systematic tendencies in the series Th(IV)-U(IV)-Np(IV)-Pu(IV). [1] Altmaier, M., Neck, V., Mueller, R., Fanghaenel, Th., Radiochim. Acta 93 (2005), in press.; [2] Rai, D., Hess, N.J., Felmy, A.R., Moore, D.A., Yui, M., Vitorge, P., a) Radiochim. Acta 84 (1999), 159, b) Radiochim. Acta 86 (1999), 89.; [3] Kitamura, A., Kohara, Y., J. Nucl

  14. Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salenCo(III complex tethering four quaternary ammonium salts

    Directory of Open Access Journals (Sweden)

    Jong Yeob Jeon

    2014-08-01

    Full Text Available The (salenCo(III complex 1 tethering four quaternary ammonium salts, which is a highly active catalyst in CO2/epoxide copolymerizations, shows high activity for propylene oxide/phthalic anhydride (PO/PA copolymerizations and PO/CO2/PA terpolymerizations. In the PO/PA copolymerizations, full conversion of PA was achieved within 5 h, and strictly alternating copolymers of poly(1,2-propylene phthalates were afforded without any formation of ether linkages. In the PO/CO2/PA terpolymerizations, full conversion of PA was also achieved within 4 h. The resulting polymers were gradient poly(1,2-propylene carbonate-co-phthalates because of the drift in the PA concentration during the terpolymerization. Both polymerizations showed immortal polymerization character; therefore, the molecular weights were determined by the activity (g/mol-1 and the number of chain-growing sites per 1 [anions in 1 (5 + water (present as impurity + ethanol (deliberately fed], and the molecular weight distributions were narrow (Mw/Mn, 1.05–1.5. Because of the extremely high activity of 1, high-molecular-weight polymers were generated (Mn up to 170,000 and 350,000 for the PO/PA copolymerization and PO/CO2/PA terpolymerization, respectively. The terpolymers bearing a substantial number of PA units (fPA, 0.23 showed a higher glass-transition temperature (48 °C than the CO2/PO alternating copolymer (40 °C.

  15. A Lewis acid β-diiminato-zinc-complex as all-rounder for co- and terpolymerisation of various epoxides with carbon dioxide.

    Science.gov (United States)

    Reiter, M; Vagin, S; Kronast, A; Jandl, C; Rieger, B

    2017-03-01

    A β-diiminato-zinc-N(SiMe 3 ) 2 complex ( 1 ) was synthesised and fully characterised, including an X-ray diffraction study. The activity of catalyst 1 towards the coupling reaction of CO 2 and various epoxides, including propylene oxide (PO), cyclohexene oxide (CHO), styrene oxide (SO), limonene oxide (LO), octene oxide (OO) and epichlorohydrin (ECH), was investigated. Terpolymerisation of CO 2 , PO and LO, as well as CO 2 , CHO and PO, was successfully realised, resulting in polymers with adjustable glass transition temperatures and transparencies. Reaction conditions such as temperature, pressure and catalyst concentration were varied to find the optimal reaction values, especially regarding LO/CO 2 . In situ IR experiments hinted that at 60 °C and a critical LO concentration, polymerisation and depolymerisation are in an equilibrium (ceiling effect). Pressurising catalyst 1 with carbon dioxide resulted in a dimeric catalyst ( 2 ) with a OSiMe 3 group as a new initiator. Homopolymerisation of different epoxides was carried out in order to explain the reactivity concerning copolymerisation reaction of CO 2 and epoxides.

  16. The coordination chemistry of dipyridylbenzene: N-deficient terpyridine or panacea for brightly luminescent metal complexes?

    Science.gov (United States)

    Williams, J A Gareth

    2009-06-01

    1,3-Di(2-pyridyl)benzene (dpybH) structurally resembles the widely-used ligand terpyridine (tpy), with which it is isoelectronic. In this critical review, following a brief overview of synthetic strategies for dpybH and derivatives, we survey the different types of complex that are possible with these ligands. Whilst metals such as ruthenium(ii), osmium(ii) and platinum(ii) give a terdentate N--C--N binding mode in which cyclometallation occurs at C(2), the ions iridium(iii), rhodium(iii) and palladium(ii) favour C(4) metallation. The latter process can be blocked by appropriate ligand modification, to allow the N--C--N mode to be accessed with these metal ions too. The luminescence properties of the complexes are discussed. A huge range of emission efficiencies are encountered amongst Ir(iii) complexes containing dpyb derivatives, according to the other ligands present. Trends can be rationalised with the aid of simple frontier-orbital considerations. The Pt(ii) complexes of dipyridylbenzenes are also intensely luminescent. Their application to contemporary organic light-emitting device (OLED) technology is discussed, including white light emitters exploiting excimer emission. Their potential as cell imaging agents amenable to time-resolved detection procedures on the microsecond timescale has also been demonstrated (118 references).

  17. Measurements of thermodynamic constants of transuranic compounds to predict their geochemistry: Carbonate complexation of Np(V) and Am(III), hydrolysis of Pu(VI) and AM(III)

    International Nuclear Information System (INIS)

    Vitorge, P.

    1984-02-01

    This work is a part of a project to build a waste disposal and to model the behaviour of the radioactive elements. The contribution consists in the prediction of the geochemistry of actinides and the measurement of thermodynamic equilibrium constants, solubility products and redox potentials (E) used in the migration model. It has shown that literature can provide values for some of these constants and proposed theoretical E(pH) diagrams and solubilities of U, Np, Pu, Am. All transport will occur essentially in the aqueous phase leaching the repository site, where hydrolysis and carbonate complexation are important chemical reactions. The hydrolysis and carbonate complexation constants have already been reviewed. The experimental results are compared with the literature data which are usually chosen to predict the solubilities and the proportions of the different forms of these actinides in natural groundwaters

  18. Preparation and electrochemical properties of core-shell carbon coated Mn-Sn complex metal oxide as anode materials for lithium-ion batteries

    Science.gov (United States)

    Zhang, Ruixue; Fang, Guoqing; Liu, Weiwei; Xia, Bingbo; Sun, Hongdan; Zheng, Junwei; Li, Decheng

    2014-02-01

    In this study, we synthesized a carbon coated Mn-Sn metal oxide composite with core-shell structure (MTO@C) via a simple glucose hydrothermal reaction and subsequent carbonization approach. When the MTO@C composite was applied as an anode material for lithium-ion batteries, it maintained a reversible capacity of 409 mA h g-1 after 200 cycles at a current density of 100 mA g-1. The uniformed and continuous carbon layer formed on the MTO nanoparticles, effectively buffered the volumetric change of the active material and increased electronic conductivity, which thus prolonged the cycling performance of the MTO@C electrode.

  19. Fixation of carbon dioxide by macrocyclic lanthanide(III) complexes under neutral conditions producing self-assembled trimeric carbonato-bridged compounds with μ3-η2:η2:η2 bonding.

    Science.gov (United States)

    Bag, Pradip; Dutta, Supriya; Biswas, Papu; Maji, Swarup Kumar; Flörke, Ulrich; Nag, Kamalaksha

    2012-03-28

    A series of mononuclear lanthanide(III) complexes [Ln(LH(2))(H(2)O)(3)Cl](ClO(4))(2) (Ln = La, Nd, Sm, Eu, Gd, Tb, Lu) of the tetraiminodiphenolate macrocyclic ligand (LH(2)) in 95 : 5 (v/v) methanol-water solution fix atmospheric carbon dioxide to produce the carbonato-bridged trinuclear complexes [{Ln(LH(2))(H(2)O)Cl}(3)(μ(3)-CO(3))](ClO(4))(4)·nH(2)O. Under similar conditions, the mononuclear Y(III) complex forms the dimeric compound [{Y(LH(2))(H(2)O)Cl}(μ(2)-CO(3)){Y(LH(2))(H(2)O)(2)}](ClO(4))(3)·4H(2)O. These complexes have been characterized by their IR and NMR ((1)H, (13)C) spectra. The X-ray crystal structures have been determined for the trinuclear carbonato-bridged compounds of Nd(III), Gd(III) and Tb(III) and the dinuclear compound of Y(III). In all cases, each of the metal centers are 8-coordinate involving two imine nitrogens and two phenolate oxygens of the macrocyclic ligand (LH(2)) whose two other imines are protonated and intramolecularly hydrogen-bonded with the phenolate oxygens. The oxygen atoms of the carbonate anion in the trinuclear complexes are bonded to the metal ions in tris-bidentate μ(3)-η(2):η(2):η(2) fashion, while they are in bis-bidentate μ(2)-η(2):η(2) mode in the Y(III) complex. The magnetic properties of the Gd(III) complex have been studied over the temperature range 2 to 300 K and the magnetic susceptibility data indicate a very weak antiferromagnetic exchange interaction (J = -0.042 cm(-1)) between the Gd(III) centers (S = 7/2) in the metal triangle through the carbonate bridge. The luminescence spectral behaviors of the complexes of Sm(III), Eu(III), and Tb(III) have been studied. The ligand LH(2) acts as a sensitizer for the metal ions in an acetonitrile-toluene glassy matrix (at 77 K) and luminescence intensities of the complexes decrease in the order Eu(3+) > Sm(3+) > Tb(3+).

  20. Structure, solution chemistry, antiproliferative actions and protein binding properties of non-conventional platinum(ii) compounds with sulfur and phosphorus donors

    NARCIS (Netherlands)

    Mügge, C.; Rothenburger, C.; Beyer, A.; Görls, H.; Gabbiani, C.; Casini, A.; Michelucci, E.; Landini, I.; Nobili, S.; Mini, E.; Messori, L.; Weigand, W.

    2011-01-01

    Twelve Pt(ii) complexes with cis-PtP2S2 pharmacophores (where P2 refers to two monodentate or one bidentate phosphane ligand and S2 is a dithiolato ligand) were prepared, characterized and evaluated as potential antiproliferative agents. The various compounds were first studied from the structural

  1. Density functional theory study of interactions between carbon monoxide and iron tetraaza macrocyclic complexes, FeTXTAA (X = -Cl, -OH, -OCH3, -NH2, and -NO2).

    Science.gov (United States)

    de Matos Mourão Neto, Isaias; Silva, Adilson Luís Pereira; Tanaka, Auro Atsushi; de Jesus Gomes Varela, Jaldyr

    2017-02-01

    This work describes a DFT level theoretical quantum study using the B3LYP functional with the Lanl2TZ(f)/6-31G* basis set to calculate parameters including the bond distances and angles, electronic configurations, interaction energies, and vibrational frequencies of FeTClTAA (iron-tetrachloro-tetraaza[14]annulene), FeTOHTAA (iron-tetrahydroxy-tetraaza[14]annulene), FeTOCH 3 TAA (iron- tetramethoxy-tetraaza[14]annulene), FeTNH 2 TAA (iron-tetraamino-tetraaza[14]annulene), and FeTNO 2 TAA (iron-tetranitro-tetraaza[14]annulene) complexes, as well as their different spin multiplicities. The calculations showed that the complexes were most stable in the triplet spin state (S = 1), while, after interaction with carbon monoxide, the singlet state was most stable. The reactivity of the complexes was evaluated using HOMO-LUMO gap calculations. Parameter correlations were performed in order to identify the best complex for back bonding (3d xz Fe → 2p x C and 3d yz Fe → 2p z C) with carbon monoxide, and the degree of back bonding increased in the order: FeTNO 2 TAA < FeTClTAA < FeTOHTAA < FeTOCH 3 TAA < FeTNH 2 TAA.

  2. DNA-Binding Studies of Some Potential Antitumor 2,2'-bipyridine Pt(II)/Pd(II) Complexes of piperidinedithiocarbamate. Their Synthesis, Spectroscopy and Cytotoxicity.

    Science.gov (United States)

    Mansouri-Torshizi, Hassan; Eslami-Moghadam, Mahboube; Divsalar, Adeleh; Saboury, Ali-Akbar

    2011-12-01

    In this study two platinum(II) and palladium(II) complexes of the type [M(bpy)(pip-dtc)]NO3 (where M=Pt(II) or Pd(II), bpy=2,2'-bipyridine, pip-dtc=piperidinedithiocarbamate) were synthesized by reaction between diaquo-2,2'-bipyridine Pt(II)/Pd(II) nitrate and sodium salt of dithiocarbamate. These cationic water soluble complexes were characterized by elemental analysis, molar conductance, IR, electronic and 1H NMR spectroscopic studies. The cyclic dithiocarbamate was found to coordinate as bidentate fasion with Pt(II) or Pd(II) center. Their biological activities were tested against chronic myelogenous leukemia cell line, K562, at micromolar concentration. The obtained cytotoxic concentration (IC50) values were much lower than cisplatin. The interaction of these complexes with highly polymerized calf thymus DNA (ct-DNA) was extensively studied by means of electronic absorption, fluorescence, circular dichroism and other measurements. The experimental results, thermodynamic and binding parameters, suggested that these complexes cooperatively bind to DNA presumably via intercalation. Moreover, the tendency of the Pt(II) complex to interact with DNA was more than that of Pd(II) complex.

  3. A structural investigation of complex I and I+III2 supercomplex from Zea mays at 11-13 angstrom resolution : Assignment of the carbonic anhydrase domain and evidence for structural heterogeneity within complex I

    NARCIS (Netherlands)

    Peters, Katrin; Dudkina, Natalya V.; Jaensch, Lothar; Braun, Hans-Peter; Boekema, Egbert J.; Jänsch, Lothar

    The projection structures of complex I and the I+III2 supercomplex from the C-4 plant Zea mays were determined by electron microscopy and single particle image analysis to a resolution of up to 11 angstrom. Maize complex I has a typical L-shape. Additionally, it has a large hydrophilic, extra-domain

  4. Preparation and electrochemical properties of core-shell carbon coated Mn–Sn complex metal oxide as anode materials for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ruixue [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); Fang, Guoqing; Liu, Weiwei [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); Changzhou Institute of Energy Storage Materials and Devices, Changzhou 213000 (China); Xia, Bingbo; Sun, Hongdan; Zheng, Junwei [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); Li, Decheng, E-mail: lidecheng@suda.edu.cn [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China)

    2014-02-15

    In this study, we synthesized a carbon coated Mn–Sn metal oxide composite with core-shell structure (MTO@C) via a simple glucose hydrothermal reaction and subsequent carbonization approach. When the MTO@C composite was applied as an anode material for lithium-ion batteries, it maintained a reversible capacity of 409 mA h g{sup −1} after 200 cycles at a current density of 100 mA g{sup −1}. The uniformed and continuous carbon layer formed on the MTO nanoparticles, effectively buffered the volumetric change of the active material and increased electronic conductivity, which thus prolonged the cycling performance of the MTO@C electrode.

  5. Preparation and electrochemical properties of core-shell carbon coated Mn–Sn complex metal oxide as anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhang, Ruixue; Fang, Guoqing; Liu, Weiwei; Xia, Bingbo; Sun, Hongdan; Zheng, Junwei; Li, Decheng

    2014-01-01

    In this study, we synthesized a carbon coated Mn–Sn metal oxide composite with core-shell structure (MTO@C) via a simple glucose hydrothermal reaction and subsequent carbonization approach. When the MTO@C composite was applied as an anode material for lithium-ion batteries, it maintained a reversible capacity of 409 mA h g −1 after 200 cycles at a current density of 100 mA g −1 . The uniformed and continuous carbon layer formed on the MTO nanoparticles, effectively buffered the volumetric change of the active material and increased electronic conductivity, which thus prolonged the cycling performance of the MTO@C electrode.

  6. Small-angle scattering, contrast variation and the study of complex composite materials: A study of the structure of carbon black

    International Nuclear Information System (INIS)

    Hjelm, R.P. Jr.; Seeger, P.A.; Wampler, W.A.

    1993-01-01

    Detailed studies are presented on the structure and aggregation of an experimental high surface area carbon black (HSA) using small-angle neutron scattering and the method of contrast variation. We find that the approximately 27 mn HSA particle form small, linear aggregates of average aggregation number 5 when suspended in cyclohexane. There is considerable density fluctuation in the interior of these particles, with the denser regions being toward the outer part of the spherically-averaged structure. This information would not have been obtained from studies of carbon black without solvent. The results will be applied to similar scattering studies on solvent-swollen bound rubber gels made from HSA-polyisoprene. These result show, however, that the strong internal fluctuations of the carbon black will limit the information that can be obtained on the structure and conformation of the elastomer in the gel. There are additional limitation from compositional heterogeneity of the sample

  7. The effect of pH on the complexation of Cd, Ni and Zn by dissolved organic carbon from leachate-polluted groundwater

    DEFF Research Database (Denmark)

    Christensen, J. B.; Christensen, Thomas Højlund

    2000-01-01

    model provided useful predictions of the complexation of Cd and Zn by DOC in the pH range 5±8, and of Ni in the pH range 5±7. At pH 8, however, the model overestimates the extent of Ni-DOC complexation to an unacceptable degree. The MINTEQA2 model predicts virtually no pH dependence for DOC complexation...

  8. Factors affecting the equilibrium constant of homolysis of complexes with metal-carbon σ bonds in aqueous solutions. Pulse radiolysis studies

    International Nuclear Information System (INIS)

    Meyerstein, D.; Ben-Gurion Univ. of the Negev, Beersheba

    1989-01-01

    Pulse-Radiolysis is a powerful technique for the determination of the equilibrium constants of the homolytic cleavage of metal-carbon σ bonds in aqueous solutions. In most systems studied the observed reaction is: L m-1 M (n+1) -R + L ↔ ML m. n + ·R. Therefore the results do not enable a direct determination of the metal-carbon bond dissociation energies. The results obtained indicate that these equilibrium constants are not directly related to the redox potential of either L .m M (n) or of ·R, or to the activation energies for the homolytic cleavage of a family of similarly substituted ethanes. (author)

  9. Carbon quantum dots and a method of making the same

    Science.gov (United States)

    Zidan, Ragaiy; Teprovich, Joseph A.; Washington, Aaron L.

    2017-08-22

    The present invention is directed to a method of preparing a carbon quantum dot. The carbon quantum dot can be prepared from a carbon precursor, such as a fullerene, and a complex metal hydride. The present invention also discloses a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride and a polymer containing a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride.

  10. Reaction between ethylenediamine and acetone on a platinum(II) complex. Crystal structure of [PtCl(en)(PBu3)][PtCl(ien)(PBu3)]Cl2 x CH3COCH3

    International Nuclear Information System (INIS)

    Kozelka, J.; Bois, C.

    1988-01-01

    The synthesis of [PtCl(en)(PBu 3 )][PtCl(ien)(PBu 3 )]Cl 2 CH 3 COCH 3 (en = ethylenediamine and ien = N-iso-propylideneethylenediamine) is reported herein. The crystal structure of the compound determined by x-ray absorption analysis and 1 H and 31 P NMR spectral data of the compound are reported. 11 references, 2 figures, 3 tables

  11. Molecular wiring of olivine LiFePO4 by ruthenium(II)-bipyridine complexes and by their assemblies with single-walled carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Exnar, I.; Zakeeruddin, S. M.; Graetzel, M.

    2008-01-01

    Roč. 112, č. 23 (2008), s. 8708-8714 ISSN 1932-7447 R&D Projects: GA MŠk LC510; GA MŠk 1P05OC069; GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : molecular wiring * LiFePO4 * carbon nanotube Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.396, year: 2008

  12. Textural analyses of carbon fiber materials by 2D-FFT of complex images obtained by high frequency eddy current imaging (HF-ECI)

    Science.gov (United States)

    Schulze, Martin H.; Heuer, Henning

    2012-04-01

    Carbon fiber based materials are used in many lightweight applications in aeronautical, automotive, machine and civil engineering application. By the increasing automation in the production process of CFRP laminates a manual optical inspection of each resin transfer molding (RTM) layer is not practicable. Due to the limitation to surface inspection, the quality parameters of multilayer 3 dimensional materials cannot be observed by optical systems. The Imaging Eddy- Current (EC) NDT is the only suitable inspection method for non-resin materials in the textile state that allows an inspection of surface and hidden layers in parallel. The HF-ECI method has the capability to measure layer displacements (misaligned angle orientations) and gap sizes in a multilayer carbon fiber structure. EC technique uses the variation of the electrical conductivity of carbon based materials to obtain material properties. Beside the determination of textural parameters like layer orientation and gap sizes between rovings, the detection of foreign polymer particles, fuzzy balls or visualization of undulations can be done by the method. For all of these typical parameters an imaging classification process chain based on a high resolving directional ECimaging device named EddyCus® MPECS and a 2D-FFT with adapted preprocessing algorithms are developed.

  13. Synthesis of carbon-14 labelled cis-malonato [(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane] platinum(II) (SKI 2053R)

    International Nuclear Information System (INIS)

    Kim, Dae-Kee; Kim, Youngseok; Rim, Jonggill; Kim, Ganghyeok; Gam, Jongsik; Song, Sungkun; Yoo, Kwanghee; Kim, Key H.

    1994-01-01

    The synthesis of 14 C-labelled cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolan e]platinum(II) from [1,4- 14 C] D-tartaric acid is described. The overall radiochemical yield of the product in a eight-step sequence was 23.8% and radiochemical purity was 98.5%. (author)

  14. Carbon-supported iron complexes as electrocatalysts for the cogeneration of hydroxylamine and electricity in a NO-H2 fuel cell: A combined electrochemical and density functional theory study

    Science.gov (United States)

    Sheng, Xia; Alvarez-Gallego, Yolanda; Dominguez-Benetton, Xochitl; Baert, Kitty; Hubin, Annick; Zhao, Hailiang; Mihaylov, Tzvetan T.; Pierloot, Kristine; Vankelecom, Ivo F. J.; Pescarmona, Paolo P.

    2018-06-01

    Carbon-supported iron complexes were investigated as electrocatalysts for the reduction of nitric oxide (NO) in a H2-NO fuel cell conceived for the production of hydroxylamine (NH2OH) with concomitant generation of electricity. Two types of iron complexes with tetradentate ligands, namely bis(salicylidene)ethylenediimine (Salen) and phthalocyanine (Pc), supported on activated carbon or graphite were prepared and evaluated as electrocatalysts, either without further treatment or after pyrolysis at 700 °C. The performance in the reduction of NO of gas diffusion cathodes based on these electrocatalysts was investigated in an electrochemical half cell (3-electrode configuration) using linear sweep voltammetry (LSV). The most promising electrocatalysts were studied further by chronoamperometric experiments in a H2-NO fuel cell, which allowed comparison in terms of power output and hydroxylamine production. Depending on the concentration of the NO feed (6 or 18%), the best electrocatalytic performance was delivered either by FePc or FeSalen. The gas diffusion electrode based on FeSalen supported on activated carbon with 0.3 wt% Fe-loading provided the highest current density (86 A/m2) and the best current efficiency (43%) towards the desired NH2OH when operating at the higher NO concentration (18%). Moreover, FeSalen offers the advantage of being cheaper than FePc. The experimental work was complemented by density functional theory (DFT) calculations, which allowed to shed more light on the reaction mechanism for the reduction of nitric oxide at the atomistic level.

  15. Ni(II, Pd(II and Pt(II complexes with ligand containing thiosemicarbazone and semicarbazone moiety: synthesis, characterization and biological investigation

    Directory of Open Access Journals (Sweden)

    SULEKH CHANDRA

    2008-07-01

    Full Text Available The synthesis of nickel(II, palladium(II and platinum(II complexes with thiosemicarbazone and semicarbazone of p-tolualdehyde are reported. All the new compounds were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, 1H-NMR, IR and electronic spectral studies. Based on the molar conductance measurements in DMSO, the complexes may be formulated as [Ni(L2Cl2] and [M(L2]Cl2 (where M = Pd(II and Pt(II due to their non-electrolytic and 1:2 electrolytic nature, respectively. The spectral data are consistent with an octahedral geometry around Ni(II and a square planar geometry for Pd(II and Pt(II, in which the ligands act as bidentate chelating agents, coordinated through the nitrogen and sulphur/oxygen atoms. The ligands and their metal complexes were screened in vitro against fungal species Alternaria alternata, Aspergillus niger and Fusarium odum, using the food poison technique.

  16. Carbonic anhydrase inhibitors. A general approach for the preparation of water-soluble sulfonamides incorporating polyamino-polycarboxylate tails and of their metal complexes possessing long-lasting, topical intraocular pressure-lowering properties.

    Science.gov (United States)

    Scozzafava, Andrea; Menabuoni, Luca; Mincione, Francesco; Supuran, Claudiu T

    2002-03-28

    Reaction of polyamino-polycarboxylic acids or their dianhydrides with aromatic/heterocyclic sulfonamides possessing a free amino/imino/hydrazino/hydroxy group afforded mono- and bis-sulfonamides containing polyamino-polycarboxylic acid moieties in their molecule. The acids/anhydrides used in synthesis included IDA, NTA, EDDA, EDTA and EDTA dianhydride, DTPA and DTPA dianhydride, EGTA and EGTA dianhydride, and EDDHA, among others. All the newly prepared derivatives showed strong affinity toward isozymes I, II, and IV of carbonic anhydrase (CA). Metal complexes of the new compounds have also been prepared. Metal ions used in such preparations included di- and trivalent main-group and transition cations, such as Zn(II), Cu(II), Al(III), etc. Some of the new sulfonamides/disulfonamides obtained in this way, as well as their metal complexes, behaved as nanomolar CA inhibitors against isozymes II and IV, being slightly less effective in inhibiting isozyme I. Some of these sulfonamides as well as their metal complexes strongly lowered intraocular pressure (IOP) when applied topically, directly into the normotensive/glaucomatous rabbit eye, as 1-2% water solutions/suspensions. The good water solubility of these sulfonamide CA inhibitors, correlated with the neutral pH of their water solutions used in the ophthalmologic applications and the long duration of action of the IOP-lowering effect, makes them interesting candidates for developing novel types of antiglaucoma drugs devoid of serious topical side effects.

  17. Evolution and estimated age of the C5 Lukala carbonate-evaporite ramp complex in the Lower Congo region (Democratic Republic of Congo): New perspectives in Central Africa

    Science.gov (United States)

    Delpomdor, F.; Van Vliet, N.; Devleeschouwer, X.; Tack, L.; Préat, A.

    2018-01-01

    New detailed lithological, sedimentological, chemostratigraphic data were obtained from exploration drilling samples on the C5 carbonate-dominated formation of the Neoproterozoic Lukala Subgroup (former Schisto-Calcaire Subgroup) from the West Congo Belt (WCB) in the Democratic Republic of Congo. This formation records the last post-Marinoan sea-level events that occurred in the whole basin, followed by the development of the Araçuaï-West Congo Orogen between 630 and 560 Ma. The C5 Formation consists of back-reef lagoonal and peritidal/sabkha cycles of ∼2.0 m in thickness, that record a short-time marine regression, rapidly flooded by a marine transgression with deposition of organic-rich argillaceous carbonates or shales under dysoxia and anoxia conditions. These dysoxic/anoxic waters were rapidly followed by a regional-scale marine transgression, favouring mixing with well-oxygenated waters, and the development of benthic Tonian to Cambro-Ordovician Obruchevella parva-type 'seagrasses' in the nearshore zones of the lagoons. New δ13C and 87Sr/86Sr isotopic data in the C5 Formation of the Lukala Subgroup are used in the frame of a correlation with the Sete Lagoas Formation in Brazil. Relatively comparable negative to positive δ13C excursions point to marine flooding of the whole basin and allow extension of the debatable Late Ediacaran age of the uppermost Sete Lagoas and C5 formations. Sr isotope ;blind dating; failed due to low Sr concentration related to a dolomitization event close 540 Ma. Several tentative datings of the C5 Formation converge to a Late Ediacaran age ranging between 575 and 540 Ma. As the overlying Mpioka folded Subgroup, the C5 series suffered the Pan African deformation, dated at 566 ± 42 Ma. Unlike the previously generally accepted interpretation, our data suggests that the Mpioka Subgroup was deposited in the Early Cambrian.

  18. A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-09-27

    Binary catalyst systems comprising a cationic Ru-CNC pincer complex and an alkali metal salt were developed for selective hydroboration of CO 2 utilizing pinacolborane at r.t. and 1 atm CO 2 , with the combination of [Ru(CNC Bn )(CO) 2 (H)][PF 6 ] and KOCO 2 t Bu producing formoxyborane in 76% yield. A bicyclic catalytic mechanism was proposed and discussed.

  19. Sulfite induced autoxidation of Cu(II/tetra/ penta and hexaglycine complexes: spectrophotometric and rotating-ring-disk glassy carbon electrode studies and analytical potentialities

    Directory of Open Access Journals (Sweden)

    Alipázaga Maria V.

    2003-01-01

    Full Text Available The oxidation of Cu(II complexes with tetra, penta and hexaglycine in borate buffer aqueous solution, by dissolved oxygen is strongly accelerated by sulfite. The formation of Cu(III complexes with maximum absorbances at 250 nm (e = 9000 mol-1 L cm-1 and 365 nm (e = 7120 mol-1 L cm-1 was also characterized by using rotating ring-disk voltammetry, whose anodic and cathodic components were observed in voltammograms recorded in solutions containing Cu(II. Voltammograms, obtained at various rotation speeds, showed that the Cu(III species electrochemically generated is not stable over the entire time window of the experiment and in solutions containing tetraglycine the overall limiting current is controlled by the kinetics of an equilibrium involving Cu(II species.The calculated first order rate constant of the decomposition was 4.37x10-3 s-1. Electrochemical experiments carried out in Cu(II solutions after the addition of relatively small amounts of sulfite demonstrated that the Cu(III species formed in the chemical reaction is the same as the one collected at the ring electrode when Cu(II is oxidized at the disk electrode in ring-disk voltammetry. The concentration of Cu(III complexes is proportional to the amount of added sulfite and the results indicated that indirect analytical methods for sulfite may be developed by means of spectrophotometric or amperometric detection of the chemically generated product.

  20. Comparative analysis of electron-density and electron-localization function for dinuclear manganese complexes with bridging boron- and carbon-centered ligands.

    Science.gov (United States)

    Götz, Kathrin; Kaupp, Martin; Braunschweig, Holger; Stalke, Dietmar

    2009-01-01

    Bonding in borylene-, carbene-, and vinylidene-bridged dinuclear manganese complexes [MnCp(CO)(2)](2)X (X = B-tBu, B = NMe(2), CH(2), C=CH(2)) has been compared by analyses based on quantum theory of atoms in molecules (QTAIM), on the electron-localization function (ELF), and by natural-population analyses. All of the density functional theory based analyses agree on the absence of a significant direct Mn-Mn bond in these complexes and confirm a dominance of delocalized bonding via the bridging ligand. Interestingly, however, the topology of both charge density and ELF related to the Mn-bridge-Mn bonding depend qualitatively on the chosen density functional (except for the methylene-bridged complex, which exhibits only one three-center-bonding attractor both in -nabla(2)rho and in ELF). While gradient-corrected functionals provide a picture with localized two-center X-Mn bonding, increasing exact-exchange admixture in hybrid functionals concentrates charge below the bridging atom and suggests a three-center bonding situation. For example, the bridging boron ligands may be described either as substituted boranes (e.g., at BLYP or BP86 levels) or as true bridging borylenes (e.g., at BHLYP level). This dependence on the theoretical level appears to derive from a bifurcation between two different bonding situations and is discussed in terms of charge transfer between X and Mn, and in the context of self-interaction errors exhibited by popular functionals.

  1. Existence of both blue-shifting hydrogen bond and Lewis acid-base interaction in the complexes of carbonyls and thiocarbonyls with carbon dioxide.

    Science.gov (United States)

    Nguyen, Tien Trung; Nguyen, Phi Hung; Tran, Thanh Hue; Minh, Tho Nguyen

    2011-08-21

    In this study, 16 gas phase complexes of the pairs of XCHZ and CO(2) (X = F, Cl, Br; Z = O, S) have been identified. Interaction energies calculated at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ level including both BSSE and ZPE corrections range from -5.6 to -10.5 kJ mol(-1) for XCHOCO(2) and from -5.7 to -9.1 kJ mol(-1) for XCHS···CO(2). Substitution of one H atom by one halogen in formaldehyde and thioformaldehyde reduces the interaction energy of XCHZ···CO(2), while a CH(3) substitution increases the interaction energy of both CH(3)CHO···CO(2) and CH(3)CHS···CO(2). NBO and AIM analyses also point out that the strength of Lewis acid-base interactions decreases going from >C1=S3···C6 to >C1=O3C6 and to >C1-X4···C6. This result suggests the higher capacity of solubility of thiocarbonyl compounds in scCO(2), providing an enormous potential application for designing CO(2)-philic materials based on the >C=S functional group in competition with >C=O. The Lewis acid-base interaction of the types >C=S···C, >C-Cl···C and >C-Br···C is demonstrated for the first time. The contribution of the hydrogen bonding interaction to the total interaction energy is larger for XCHS···CO(2) than for XCHO···CO(2). Upon complexation, a contraction of the C1-H2 bond length and a blue shift of its stretching frequency have been observed, as compared to the isolated monomer, indicating the existence of a blue-shifting hydrogen bond in all complexes examined. Calculated results also lend further support for the viewpoint that when acting as proton donor, a C-H bond having a weaker polarization will induce a stronger distance contraction and frequency blue shift upon complexation, and vice versa.

  2. Electrochemical quantification of the thermodynamic equilibrium constant of the tenoxicam-β-cyclodextrin inclusion complex formed on the surface of a poly-β cyclodextrin-modified carbon paste electrode

    International Nuclear Information System (INIS)

    Guzmán-Hernández, D.S.; Palomar-Pardavé, M.; Rojas-Hernández, A.; Corona-Avendaño, S.; Romero-Romo, M.; Ramírez-Silva, M.T.

    2014-01-01

    Graphical abstract: - Highlights: • A carbon paste electrode (CPE) was modified with a β-CD polymer. • Tenoxicam oxidation on the CPE/poly-β-CD was adsorption controlled. • Influence of pH, scan rate, angular velocity and concentration was evaluated. • Fittings of i-E plots were done considering an irreversible surface reaction. • Electrochemical evaluation of the surface inclusion constant is presented. - Abstract: In this work it is shown that when a carbon paste electrode, CPE, is modified with a β-cyclodextrin polymer, the tenoxicam oxidation becomes an adsorption controlled process due to formation of a surface inclusion complex with the β-CD molecules comprising the surface of the polymer. It was found that such surface inclusion complex can be formed independently of the tenoxicam predominant species, Tenox’, in the aqueous solution namely: H 2 Tenox + , HTenox or Tenox − , depending on the solution pH. The electrochemical quantification of the thermodynamic constant of the equilibrium Tenox’ + β-CD (polymer) = Tenox’-β-CD (polymer) was estimated as log K incl. = 4.26 ± 0.01. Furthermore, from the analyses of the experimental voltammograms according with Laviron's equation for an irreversible surface reaction [E. Laviron, J. Electroanal. Chem. 52 (1974) 355-393] it is shown that the surface concentration, Γ R , of tenoxicam increases as its concentration in solution does, reaching a maximum value of 1.51 × 10 −10 mol cm −2 at 64 μM

  3. Method for the preparation of carbon fiber from polyolefin fiber precursor, and carbon fibers made thereby

    Science.gov (United States)

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2015-08-04

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  4. Carbonyl Activation by Borane Lewis Acid Complexation: Transition States of H2 Splitting at the Activated Carbonyl Carbon Atom in a Lewis Basic Solvent and the Proton-Transfer Dynamics of the Boroalkoxide Intermediate.

    Science.gov (United States)

    Heshmat, Mojgan; Privalov, Timofei

    2017-07-06

    By using transition-state (TS) calculations, we examined how Lewis acid (LA) complexation activates carbonyl compounds in the context of hydrogenation of carbonyl compounds by H 2 in Lewis basic (ethereal) solvents containing borane LAs of the type (C 6 F 5 ) 3 B. According to our calculations, LA complexation does not activate a ketone sufficiently enough for the direct addition of H 2 to the O=C unsaturated bond; but, calculations indicate a possibly facile heterolytic cleavage of H 2 at the activated and thus sufficiently Lewis acidic carbonyl carbon atom with the assistance of the Lewis basic solvent (i.e., 1,4-dioxane or THF). For the solvent-assisted H 2 splitting at the carbonyl carbon atom of (C 6 F 5 ) 3 B adducts with different ketones, a number of TSs are computed and the obtained results are related to insights from experiment. By using the Born-Oppenheimer molecular dynamics with the DFT for electronic structure calculations, the evolution of the (C 6 F 5 ) 3 B-alkoxide ionic intermediate and the proton transfer to the alkoxide oxygen atom were investigated. The results indicate a plausible hydrogenation mechanism with a LA, that is, (C 6 F 5 ) 3 B, as a catalyst, namely, 1) the step of H 2 cleavage that involves a Lewis basic solvent molecule plus the carbonyl carbon atom of thermodynamically stable and experimentally identifiable (C 6 F 5 ) 3 B-ketone adducts in which (C 6 F 5 ) 3 B is the "Lewis acid promoter", 2) the transfer of the solvent-bound proton to the oxygen atom of the (C 6 F 5 ) 3 B-alkoxide intermediate giving the (C 6 F 5 ) 3 B-alcohol adduct, and 3) the S N 2-style displacement of the alcohol by a ketone or a Lewis basic solvent molecule. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Covalent attachment of pyridine-type molecules to glassy carbon surfaces by electrochemical reduction of in situ generated diazonium salts. Formation of ruthenium complexes on ligand-modified surfaces

    International Nuclear Information System (INIS)

    Yesildag, Ali; Ekinci, Duygu

    2010-01-01

    In this study, pyridine, quinoline and phenanthroline molecules were covalently bonded to glassy carbon (GC) electrode surfaces for the first time using the diazonium modification method. Then, the complexation ability of the modified films with ruthenium metal cations was investigated. The derivatization of GC surfaces with heteroaromatic molecules was achieved by electrochemical reduction of the corresponding in situ generated diazonium salts. X-ray photoelectron spectroscopy (XPS) was used to confirm the attachment of heteroaromatic molecules to the GC surfaces and to determine the surface concentration of the films. The barrier properties of the modified GC electrodes were studied in the presence of redox probes such as Fe(CN) 6 3- and Ru(NH 3 ) 6 3+ by cyclic voltammetry. Additionally, the presence of the resulting organometallic films on the surfaces was verified by XPS after the chemical transformation of the characterized ligand films to the ruthenium complex films. The electrochemical behavior of these films in acetonitrile solution was investigated using voltammetric methods, and the surface coverage of the organometallic films was determined from the reversible metal-based Ru(II)/Ru(III) oxidation waves.

  6. Covalent attachment of pyridine-type molecules to glassy carbon surfaces by electrochemical reduction of in situ generated diazonium salts. Formation of ruthenium complexes on ligand-modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yesildag, Ali [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey); Ekinci, Duygu, E-mail: dekin@atauni.edu.t [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey)

    2010-09-30

    In this study, pyridine, quinoline and phenanthroline molecules were covalently bonded to glassy carbon (GC) electrode surfaces for the first time using the diazonium modification method. Then, the complexation ability of the modified films with ruthenium metal cations was investigated. The derivatization of GC surfaces with heteroaromatic molecules was achieved by electrochemical reduction of the corresponding in situ generated diazonium salts. X-ray photoelectron spectroscopy (XPS) was used to confirm the attachment of heteroaromatic molecules to the GC surfaces and to determine the surface concentration of the films. The barrier properties of the modified GC electrodes were studied in the presence of redox probes such as Fe(CN){sub 6}{sup 3-} and Ru(NH{sub 3}){sub 6}{sup 3+} by cyclic voltammetry. Additionally, the presence of the resulting organometallic films on the surfaces was verified by XPS after the chemical transformation of the characterized ligand films to the ruthenium complex films. The electrochemical behavior of these films in acetonitrile solution was investigated using voltammetric methods, and the surface coverage of the organometallic films was determined from the reversible metal-based Ru(II)/Ru(III) oxidation waves.

  7. Construction of a new functional platform by grafting poly(4-vinylpyridine) in multi-walled carbon nanotubes for complexing copper ions aiming the amperometric detection of L-cysteine

    International Nuclear Information System (INIS)

    Carvalho Castro e Silva, Cecília de; Breitkreitz, Márcia Cristina; Santhiago, Murilo; Crispilho Corrêa, Cátia; Tatsuo Kubota, Lauro

    2012-01-01

    Highlights: ► Construction of new nanostructured platform based on MWCNTs–PVP to complex copper(II) ions. ► Development of an amperometric sensor for highly selective determination of Cys in food supplement samples. ► Combination of nanocomposite and the copper(II) ions causes a dramatic enhancement in the sensitivity of Cys quantification at low overpotential. - Abstract: This work describes the preparation of an amperometric sensor for electrocatalytical detection of L-cysteine (Cys). The developed sensor is based on a functional platform to complex copper ions on multi-walled carbon nanotubes (MWCNTs) modified with poly-4-vinylpyridine (PVP) through an in situ polymerization. The obtained values for the kinetic constants of heterogeneous electron transfer rate (k s ) and for chemical reaction (k obs ) between Cu 2+ and cysteine were 5.78 s −1 and 6.96 L mol −1 s −1 , respectively. The analytical curve showed a linear response range for detecting L-cysteine in concentrations from 5 to 60 μmol L −1 . The detection and quantification limits obtained were 1.50 and 5.00 μmol L −1 , respectively with a response time of 0.10 s at an applied potential of 150 mV vs SCE.

  8. Spin–Orbit TDDFT Electronic Structure of Diplatinum(II,II) Complexes

    Czech Academy of Sciences Publication Activity Database

    Záliš, Stanislav; Lam, Y.; Ch.; Gray, H. B.; Vlček, Antonín

    2015-01-01

    Roč. 54, č. 7 (2015), s. 3491-3500 ISSN 0020-1669 R&D Projects: GA MŠk LH13015 Institutional support: RVO:61388955 Keywords : BINUCLEAR PLATINUM(II) PHOTOCHEMISTRY * DENSITY-FUNCTIONAL THEORY * SPECTROSCOPIC PROPERTIES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.820, year: 2015

  9. Controlled synthesis, formation mechanism, and carbon oxidation properties of Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates prepared with a coordination-complex method

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Rui [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China); You, Junhua [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870 (China); Han, Fei; Li, Chaoyang; Zheng, Guiyuan; Xiao, Weicheng [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); Liu, Xuanwen, E-mail: lxw@mail.neuq.edu.cn [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China)

    2017-02-28

    Highlights: • The crystallization mechanism relies on Ho{sup 3+} and Cu{sup 2+} diffusion. • The Ho{sub 2}Cu{sub 2}O{sub 5} particles are refined by the coordination complex method under N{sub 2} environment. • The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon is enhanced. - Abstract: Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates with perovskite structures were synthesized via a simple solution method (SSM) and a coordination-complex method (CCM) using [HoCu(3,4-pdc){sub 2}(OAc)(H{sub 2}O){sub 3}]·8H{sub 2}O (L = 3,4-pyridinedicarboxylic acid) as a precursor. The CCM was also performed in an N{sub 2} environment (CCMN) under various calcination conditions. The crystallization processes were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Ho{sub 2}Cu{sub 2}O{sub 5} formed through the diffusion of CuO into Ho{sub 2}O{sub 3} particles. Cu{sup 2+} diffused faster than Ho{sup 3+} during this process. The initial products of CCMN (along with the thermal decomposition products) were initially laminarized in the N{sub 2} atmosphere, which prevented the growth of CuO particles and decreased the size of the Ho{sub 2}Cu{sub 2}O{sub 5} particles. The final Ho{sub 2}Cu{sub 2}O{sub 5} particles from CCMN had a nanoplate morphology with an average thickness of 75 nm. The decomposition of organic molecules and protection from N{sub 2} played important roles in determining the morphology of the resulting Ho{sub 2}Cu{sub 2}O{sub 5}. The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon was characterized using a specific surface area measurement and thermogravimetric analysis, which revealed that the samples produced by CCMN had the highest catalytic activity.

  10. Molecular complexity from polyunsaturated substrates: the gold catalysis approach.

    Science.gov (United States)

    Fensterbank, Louis; Malacria, Max

    2014-03-18

    Over the last two decades, electrophilic catalysis relying on platinum(II), gold(I), and gold(III) salts has emerged as a remarkable synthetic methodology. Chemists have discovered a large variety of organic transformations that convert a great assortment of highly functionalized precursors into valuable final products. In many cases, these methodologies offer unique features, allowing access to unprecedented molecular architectures. Due to the mild reaction conditions and high function compatibility, scientists have successfully developed applications in total synthesis of natural products, as well as in asymmetric catalysis. In addition, all these developments have been accompanied by the invention of well-tailored catalysts, so that a palette of different electrophilic agents is now commercially available or readily synthesized at the bench. In some respects, researchers' interests in developing homogeneous gold catalysis can be compared with the Californian gold rush of the 19th century. It has attracted into its fervor thousands of scientists, providing a huge number of versatile and important reports. More notably, it is clear that the contribution to the art of organic synthesis is very valuable, though the quest is not over yet. Because they rely on the intervention of previously unknown types of intermediates, new retrosynthetic disconnections are now possible. In this Account, we discuss our efforts on the use of readily available polyunsaturated precursors, such as enynes, dienynes, allenynes, and allenenes to give access to highly original polycyclic structures in a single operation. These transformations transit via previously undescribed intermediates A, B, D, F, and H that will be encountered later on. All these intermediates have been determined by both ourselves and others by DFT calculations and in some cases have been confirmed on the basis of experimental data. In addition, dual gold activation can be at work in some of these transformations

  11. Complexity explained

    CERN Document Server

    Erdi, Peter

    2008-01-01

    This book explains why complex systems research is important in understanding the structure, function and dynamics of complex natural and social phenomena. Readers will learn the basic concepts and methods of complex system research.

  12. Carbon isotopes in mollusk shell carbonates

    Science.gov (United States)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  13. Complex chemistry

    International Nuclear Information System (INIS)

    Kim, Bong Gon; Kim, Jae Sang; Kim, Jin Eun; Lee, Boo Yeon

    2006-06-01

    This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

  14. Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D., E-mail: mdvargas@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica; Alves, Wagner A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Departamento de Quimica; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V. [Universidade Federal do Ceara (UFCE), Fortaleza, CE (Brazil). Centro de Ciencias da Saude. Departamento de Fisiologia e Farmacologia

    2013-04-15

    Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl{sub 2}(OH){sub 2}] 1b-3b(HL = 2-hydroxy-3-[(R{sup 1} -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R{sup 1} = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl{sub 2}] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO{sup -}, i.e., L{sup -}) redox process and irreversible process attributed to the reduction of the Pt{sup 4+}/Pt{sup 2+} pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH{sub 3}){sub 2}Cl{sub 2}(OH){sub 2}]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt{sup 4+}/Pt{sup 2+} reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC{sub 50} values have been observed for 2b-3b, which bear ligands with the largest R{sup 1} groups (HL2-HL3) being the most lipophilic. Furthermore similar IC{sub 50} values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

  15. Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

    International Nuclear Information System (INIS)

    Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D.; Alves, Wagner A.; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V.

    2013-01-01

    Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl 2 (OH) 2 ] 1b-3b(HL = 2-hydroxy-3-[(R 1 -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R 1 = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl 2 ] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO - , i.e., L - ) redox process and irreversible process attributed to the reduction of the Pt 4+ /Pt 2+ pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH 3 ) 2 Cl 2 (OH) 2 ]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt 4+ /Pt 2+ reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC 50 values have been observed for 2b-3b, which bear ligands with the largest R 1 groups (HL2-HL3) being the most lipophilic. Furthermore similar IC 50 values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

  16. Selenophene transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    White, Carter James [Iowa State Univ., Ames, IA (United States)

    1994-07-27

    This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the η5- and the η1(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The 77Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of η1(S)-bound thiophenes, η1(S)-benzothiophene and η1(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the η1(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh3)Re(2-benzothioenylcarbene)]O3SCF3 was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the η1(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

  17. Aqueous complexes of lanthanides(III) and actinides(III) with the carbonate and sulphate ions. Thermodynamic study by time-resolved laser-induced fluorescence spectroscopy and electro-spray-ionisation mass spectrometry; Complexes aqueux de lanthanides (3) et actinides (3) avec les ions carbonate et sulfate. Etude thermodynamique par spectrofluorimetrie laser resolue en temps et spectrometrie de masse a ionisation electrospray

    Energy Technology Data Exchange (ETDEWEB)

    Vercouter, Th

    2005-03-15

    The prediction of the environmental impact of a possible geological disposal of radioactive wastes is supported by the thermodynamic modelling of the radionuclides behaviour in the groundwater. In this framework, the analogy between lanthanides and actinides(III) is confirmed by a critical analysis of the literature and the comparison with experimental results obtained here. The limiting complex, Eu(CO{sub 3}){sub 3}{sup 3-}, is identified by solubility measurements in Na{sub 2}CO{sub 3} solutions. Then the formation constants of the complexes Eu(CO{sub 3}){sub i}{sup 3-2i} (i=1-3) and Eu(SO{sub 4}){sub i}{sup 3-2i} (i=1-2) are measured by TRLFS. The formation of aqueous LaSO{sub 4}{sup +} is studied by ESI-MS and is in good agreement with the expected speciation. The enthalpy and entropy of the reaction Cm(CO{sub 3}){sub 2}{sup -} + CO{sub 3}{sup 2-} {r_reversible} Cm(CO{sub 3}){sub 3}{sup 3-} are deduced from TRLFS measurements of the equilibrium constant between 10 and 70 C. The ionic strength effect is calculated using the SIT formula. (author)

  18. Dispersions of Carbon nanotubes in Polymer Matrices

    Science.gov (United States)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  19. Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2.

    Science.gov (United States)

    Lyu, Lai; Yan, Dengbiao; Yu, Guangfei; Cao, Wenrui; Hu, Chun

    2018-04-03

    Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO 2 substrate (CN-Cu(II)-CuAlO 2 ) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO 2 . According to the characterization, Cu(II) generation on the surface of CuAlO 2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C-O-Cu bridges between CN and Cu(II)-CuAlO 2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation-π interactions through the C-O-Cu bridges in CN-Cu(II)-CuAlO 2 . During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H 2 O 2 to • OH, and the electron-poor center around C captures electrons from H 2 O 2 or pollutants and diverts them to the electron-rich area via the C-O-Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.

  20. Carbon/carbon composite materials

    International Nuclear Information System (INIS)

    Thebault, J.; Orly, P.

    2006-01-01

    Carbon/carbon composites are singular materials from their components, their manufacturing process as well as their characteristics. This paper gives a global overview of these particularities and applications which make them now daily used composites. (authors)

  1. (II) complexes

    African Journals Online (AJOL)

    activities of Schiff base tin (II) complexes. Neelofar1 ... Conclusion: All synthesized Schiff bases and their Tin (II) complexes showed high antimicrobial and ...... Singh HL. Synthesis and characterization of tin (II) complexes of fluorinated Schiff bases derived from amino acids. Spectrochim Acta Part A: Molec Biomolec.

  2. NanoCarbon 2011. Selected works from the Brazilian carbon meeting

    Energy Technology Data Exchange (ETDEWEB)

    Avellaneda, Cesar (ed.) [Univ. Federal de Pelotas (Brazil). Centro de Desenvolvimento Tecnologico

    2013-02-01

    This book presents eight selected papers from the Brazilian Carbon Meeting 2011. It contains the following topics: Review of field emission from carbon Nanotubes: Highlighting measuring energy spread. - Synthesis and characterisation of carbon nanocomposites. - Performance of Ni/MgAl{sub 2}O{sub 4} catalyst obtained by a metal-chitosan complex method in methane decomposition reaction with production of carbon nanotubes. - The use of nanostructures for DNA transfection. - Applications of carbon nanotubes in oncology. - CNTs/TiO2 composites. - Synthesis of vertically aligned carbon nanotubes by CVD Technique: A review. - Thermoset three-component composite systems using carbon nantubes.

  3. Communication complexity and information complexity

    Science.gov (United States)

    Pankratov, Denis

    Information complexity enables the use of information-theoretic tools in communication complexity theory. Prior to the results presented in this thesis, information complexity was mainly used for proving lower bounds and direct-sum theorems in the setting of communication complexity. We present three results that demonstrate new connections between information complexity and communication complexity. In the first contribution we thoroughly study the information complexity of the smallest nontrivial two-party function: the AND function. While computing the communication complexity of AND is trivial, computing its exact information complexity presents a major technical challenge. In overcoming this challenge, we reveal that information complexity gives rise to rich geometrical structures. Our analysis of information complexity relies on new analytic techniques and new characterizations of communication protocols. We also uncover a connection of information complexity to the theory of elliptic partial differential equations. Once we compute the exact information complexity of AND, we can compute exact communication complexity of several related functions on n-bit inputs with some additional technical work. Previous combinatorial and algebraic techniques could only prove bounds of the form theta( n). Interestingly, this level of precision is typical in the area of information theory, so our result demonstrates that this meta-property of precise bounds carries over to information complexity and in certain cases even to communication complexity. Our result does not only strengthen the lower bound on communication complexity of disjointness by making it more exact, but it also shows that information complexity provides the exact upper bound on communication complexity. In fact, this result is more general and applies to a whole class of communication problems. In the second contribution, we use self-reduction methods to prove strong lower bounds on the information

  4. Carbonate binding to copper(II) in solution: mixed-ligand complex formation and its application to the isolation and separation of the three isomers of [Cu(bpp)(H2O)][ClO4]2 [bpp = 2,6-bis(pyrrolidin-2-yl)pyridine

    OpenAIRE

    Bernauer, Klaus; Godefroy, Isabelle; Cabort, Amel; Guicher, Nathalie; Stoeckli-Evans, Helen; Süss-Fink, Georg

    2006-01-01

    The binding of the carbonate anion to [Cu(meso-bpp)(H2O)]2+ and rac-[Cu(bpp)(H2O)]2+ [bpp = 2,6-bis(pyrrolidin-2-yl)pyridine] in aqueous solution has been investigated. Formation constants of the carbonato complexes [Cu(meso-bpp)(CO3)] and rac-[Cu(bpp)(CO3)] (1.02 × 103 M–1 and 1.77 × 103 M–1, respectively, µ= 0.70 M) have been calculated from spectrophotometric measurements. The formation of these Cu2+ complexes can also be used for an improved synthesis and an easy isolation of the three di...

  5. An unprecedented up-field shift in the 13C NMR spectrum of the carboxyl carbons of the lantern-type dinuclear complex TBA[Ru2(O2CCH3)4Cl2] (TBA+ = tetra(n-butyl)ammonium cation).

    Science.gov (United States)

    Hiraoka, Yuya; Ikeue, Takahisa; Sakiyama, Hiroshi; Guégan, Frédéric; Luneau, Dominique; Gillon, Béatrice; Hiromitsu, Ichiro; Yoshioka, Daisuke; Mikuriya, Masahiro; Kataoka, Yusuke; Handa, Makoto

    2015-08-14

    A large up-field shift (-763 ppm) has been observed for the carboxyl carbons of the dichlorido complex TBA[Ru(2)(O(2)CCH(3))(4)Cl(2)] (TBA(+) = tetra(n-butyl)ammonium cation) in the (13)C NMR spectrum (CD(2)Cl(2) at 25 °C). The DFT calculations showed spin delocalization from the paramagnetic Ru(2)(5+) core to the ligands, in agreement with the large up-field shift.

  6. Carbon dioxide, oxygen, and pH detection in animal adipose tissue by means of extracorporeal microdialysis

    Science.gov (United States)

    Baldini, F.; Bizzarri, A.; Cajlakovic, M.; Feichtner, F.; Gianesello, L.; Giannetti, A.; Gori, G.; Konrad, C.; Mencaglia, A. A.; Mori, E.; Pavoni, V.; Perna, A. M.; Trono, C.

    2007-05-01

    Atypical physiological symptoms can be developed in healthy people under critically ill conditions. pH, pO II and pCO II are informative indicators of the conditions of a living system and can be valuable in determining the physiologic status of the critically ill patients. The continuous monitoring of these small molecules into the interstitial fluid (ISF) is a promising approach to reduce diagnostic blood loss and painful stress associated with blood sampling. Microdialysis is the approach followed for the extraction of the sample from the subcutaneous adipose tissue; the drawn interstitial fluid flows through a microfluidic circuit formed by the microdialysis catheter in series with a glass capillary on the internal wall of which the appropriate chemistry for sensing is immobilised. Absorption changes for pH sensor and modulation of the fluorescence lifetime for pO II and pCO II are the working principle. Phenol red covalently bound into the internal wall of a glass capillary by means of the Mannich reaction and platinum(II) tetrakis-pentafluorophenyl-porphyrine entrapped within a polymerised polystyrene layer are the chemical transducers used for pH and oxygen detection; the ion pair 8- hydroxypyrene-1,3,6-trisulfonic acid trisodium salt/ tetraoctylammonium hydroxide, dissolved in a silicon-based polymeric matrix, is used for the carbon dioxide detection. A suitable hemorrhagic shock model was developed in order to validate clinically the developed sensors in the condition of extreme stress and the obtained results show that the adipose tissue can become an alternative site for the continuous oitoring of pH, pO II and pCO II.

  7. Complexity Plots

    KAUST Repository

    Thiyagalingam, Jeyarajan

    2013-06-01

    In this paper, we present a novel visualization technique for assisting the observation and analysis of algorithmic complexity. In comparison with conventional line graphs, this new technique is not sensitive to the units of measurement, allowing multivariate data series of different physical qualities (e.g., time, space and energy) to be juxtaposed together conveniently and consistently. It supports multivariate visualization as well as uncertainty visualization. It enables users to focus on algorithm categorization by complexity classes, while reducing visual impact caused by constants and algorithmic components that are insignificant to complexity analysis. It provides an effective means for observing the algorithmic complexity of programs with a mixture of algorithms and black-box software through visualization. Through two case studies, we demonstrate the effectiveness of complexity plots in complexity analysis in research, education and application. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.

  8. Carbonate aquifers

    Science.gov (United States)

    Cunningham, Kevin J.; Sukop, Michael; Curran, H. Allen

    2012-01-01

    Only limited hydrogeological research has been conducted using ichnology in carbonate aquifer characterization. Regardless, important applications of ichnology to carbonate aquifer characterization include its use to distinguish and delineate depositional cycles, correlate mappable biogenically altered surfaces, identify zones of preferential groundwater flow and paleogroundwater flow, and better understand the origin of ichnofabric-related karst features. Three case studies, which include Pleistocene carbonate rocks of the Biscayne aquifer in southern Florida and Cretaceous carbonate strata of the Edwards–Trinity aquifer system in central Texas, demonstrate that (1) there can be a strong relation between ichnofabrics and groundwater flow in carbonate aquifers and (2) ichnology can offer a useful methodology for carbonate aquifer characterization. In these examples, zones of extremely permeable, ichnofabric-related macroporosity are mappable stratiform geobodies and as such can be represented in groundwater flow and transport simulations.

  9. Hydrology and landscape structure control subalpine catchment carbon export

    Science.gov (United States)

    Vincent Jerald Pacific

    2009-01-01

    Carbon export from high elevation ecosystems is a critical component of the global carbon cycle. Ecosystems in northern latitudes have become the focus of much research due to their potential as large sinks of carbon in the atmosphere. However, there exists limited understanding of the controls of carbon export from complex mountain catchments due to strong spatial and...

  10. Two-point versus multiple-point geostatistics: the ability of geostatistical methods to capture complex geobodies and their facies associations—an application to a channelized carbonate reservoir, southwest Iran

    International Nuclear Information System (INIS)

    Hashemi, Seyyedhossein; Javaherian, Abdolrahim; Ataee-pour, Majid; Khoshdel, Hossein

    2014-01-01

    Facies models try to explain facies architectures which have a primary control on the subsurface heterogeneities and the fluid flow characteristics of a given reservoir. In the process of facies modeling, geostatistical methods are implemented to integrate different sources of data into a consistent model. The facies models should describe facies interactions; the shape and geometry of the geobodies as they occur in reality. Two distinct categories of geostatistical techniques are two-point and multiple-point (geo) statistics (MPS). In this study, both of the aforementioned categories were applied to generate facies models. A sequential indicator simulation (SIS) and a truncated Gaussian simulation (TGS) represented two-point geostatistical methods, and a single normal equation simulation (SNESIM) selected as an MPS simulation representative. The dataset from an extremely channelized carbonate reservoir located in southwest Iran was applied to these algorithms to analyze their performance in reproducing complex curvilinear geobodies. The SNESIM algorithm needs consistent training images (TI) in which all possible facies architectures that are present in the area are included. The TI model was founded on the data acquired from modern occurrences. These analogies delivered vital information about the possible channel geometries and facies classes that are typically present in those similar environments. The MPS results were conditioned to both soft and hard data. Soft facies probabilities were acquired from a neural network workflow. In this workflow, seismic-derived attributes were implemented as the input data. Furthermore, MPS realizations were conditioned to hard data to guarantee the exact positioning and continuity of the channel bodies. A geobody extraction workflow was implemented to extract the most certain parts of the channel bodies from the seismic data. These extracted parts of the channel bodies were applied to the simulation workflow as hard data

  11. Complexity Theory

    Science.gov (United States)

    Lee, William H K.

    2016-01-01

    A complex system consists of many interacting parts, generates new collective behavior through self organization, and adaptively evolves through time. Many theories have been developed to study complex systems, including chaos, fractals, cellular automata, self organization, stochastic processes, turbulence, and genetic algorithms.

  12. Interaction of cis-diamminediaquoplatinum(II) with adenosylcobalamin and alkylcobalamins

    Energy Technology Data Exchange (ETDEWEB)

    Hogenkamp, H P.C. [Univ. of Minnesota, Minneapolis; Kohlmiller, N A; Howsinger, R; Walker, T E; Matwiyoff, N A

    1980-01-01

    The interaction of cis-diamminediaquoplatinum(II) nitrate with adenosylcobalamin and a series of alkylcobalamins was studied by carbon-13 nuclear magnetic resonance spectroscopy and by electronic spectroscopy. With these cobalamins cis-(Pt(NH/sub 3/)/sub 2/(OH/sub 2/)/sub 2/)/sup 2 +/ forms adducts in which N(3) of the 5,6-methylbenzimidazole moiety is co-ordinated to platinum(II) rather than to cobalt(III) of the corrin. The chemical shifts of the 5'-methylene carbon of adenosylcobalamin-platinum adduct and of the Co-methyl carbon of the methylcobalamin-platinum adduct are characteristic of these cobalamins in the base-off form. Furthermore, these cobalamin-platinum complexes have visible spectra identical to those of the cobalamins in acidic solution. The /sup 13/C NMR spectrum of the adenosylcobalamin-platinum complex suggests the presence of a second adduct in which platinum(II) complexes are co-ordinated to both the N(3) of the 5,6-dimethylbenzimidazole nucleotide and to N(7) of the 5'-deoxyadenosyl moiety. The rate of the alkylcobalamin-platinum(II) adduct formation is determined by the strength of the cobalt(III)-5,6-dimethylbenzimidazole co-ordinate bond. Thus, adenosylcobalamin reacts much faster than adenosylepicobalamin to form the cobalamin-platinum(II) adduct.

  13. Carbon-On-Carbon Manufacturing

    Science.gov (United States)

    Mungas, Gregory S. (Inventor); Buchanan, Larry (Inventor); Banzon, Jr., Jose T. (Inventor)

    2017-01-01

    The presently disclosed technology relates to carbon-on-carbon (C/C) manufacturing techniques and the resulting C/C products. One aspect of the manufacturing techniques disclosed herein utilizes two distinct curing operations that occur at different times and/or using different temperatures. The resulting C/C products are substantially non-porous, even though the curing operation(s) substantially gasify a liquid carbon-entrained filler material that saturates a carbon fabric that makes up the C/C products.

  14. Porous carbons

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Carbon in dense as well as porous solid form is used in a variety of applications. Activated porous carbons are made through pyrolysis and activation of carbonaceous natural as well as synthetic precursors. Pyrolysed woods replicate the structure of original wood but as such possess very low surface areas and ...

  15. Carbon photonics

    Energy Technology Data Exchange (ETDEWEB)

    Konov, V I [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-11-30

    The properties of new carbon materials (single-crystal and polycrystalline CVD diamond films and wafers, single-wall carbon nanotubes and graphene) and the prospects of their use as optical elements and devices are discussed. (optical elements of laser devices)

  16. Managing Complexity

    DEFF Research Database (Denmark)

    Maylath, Bruce; Vandepitte, Sonia; Minacori, Patricia

    2013-01-01

    and into French. The complexity of the undertaking proved to be a central element in the students' learning, as the collaboration closely resembles the complexity of international documentation workplaces of language service providers. © Association of Teachers of Technical Writing.......This article discusses the largest and most complex international learning-by-doing project to date- a project involving translation from Danish and Dutch into English and editing into American English alongside a project involving writing, usability testing, and translation from English into Dutch...

  17. Complex variables

    CERN Document Server

    Fisher, Stephen D

    1999-01-01

    The most important topics in the theory and application of complex variables receive a thorough, coherent treatment in this introductory text. Intended for undergraduates or graduate students in science, mathematics, and engineering, this volume features hundreds of solved examples, exercises, and applications designed to foster a complete understanding of complex variables as well as an appreciation of their mathematical beauty and elegance. Prerequisites are minimal; a three-semester course in calculus will suffice to prepare students for discussions of these topics: the complex plane, basic

  18. INTERACTION OF CARBON DIOXIDE WITH CARBON ADSORBENTS BELOW 400 C

    Energy Technology Data Exchange (ETDEWEB)

    Deitz, V R; Carpenter, F G; Arnold, R G

    1963-06-15

    The adsorption of carbon dioxide on carbon adsorbents (FT carbon, coconut charcoal, acid-washed bone char) and adsorbents containing basic calcium phosphate (hydroxylapatite, bone char, ash of bone char) was studied. Special consideration was given to the pretreatment of the materials. The carbons equilibrated as rapidly as the temperature; the basic calcium phosphates showed a rapid initial adsorption followed by a very slow rate which continued for days. Linear adsorption isotherms were found on FT carbon and the isosteric heats varied slightiy with coverage. The isotherms for the remaining materials had varying curvature and were for the most part in the same sequence as the estimated surface areas. The isosteric heats of carbon dioxide correlated very well with the magnitude of surface hydroxyl groups, an estimate of which was made from the chemical composition. There appeared to be three increasing levels of interaction: (1) pure physical adsorption; (2) an adsorption complex having 'bicarbonate structure'; and (3) an adsorption complex having 'carbonate structure'. (auth)

  19. Softball Complex

    Science.gov (United States)

    Ellis, Jim

    1977-01-01

    The Parks and Recreation Department of Montgomery, Alabama, has developed a five-field softball complex as part of a growing community park with facilities for camping, golf, aquatics, tennis, and picnicking. (MJB)

  20. Lecithin Complex

    African Journals Online (AJOL)

    1Department of Food Science and Engineering, Xinyang College of Agriculture and ... Results: The UV and IR spectra of the complex showed an additive effect of polydatin-lecithin, in which .... Monochromatic Cu Ka radiation (wavelength =.

  1. Carbon price volatility: Evidence from EU ETS

    International Nuclear Information System (INIS)

    Feng, Zhen-Hua; Zou, Le-Le; Wei, Yi-Ming

    2011-01-01

    This paper examines carbon price volatility using data from the European Union Emission Trading Scheme from a nonlinear dynamics point of view. First, we use a random walk model, including serial correlation and variance ratio tests, to determine whether carbon price history information is fully reflected in current carbon price. The empirical research results show that carbon price is not a random walk: the price history information is not fully reflected in current carbon price. Second, use R/S, modified R/S and ARFIMA to analyse the memory of carbon price history. For the period April 2005-December 2008, the modified Hurst index of the carbon price is 0.4859 and the d value of ARFIMA is -0.1191, indicating short-term memory of the carbon price. Third, we use chaos theory to analyse the influence of the carbon market internal mechanism on carbon price, i.e., the market's positive and negative feedback mechanism and the heterogeneous environment. Chaos theory proves that the correlation dimension of carbon price increases. The maximal Lyapunov exponent is positive and large. There is no obvious complex endogenous phenomenon of nonlinear dynamics the carbon price fluctuation. The carbon market is mildly chaotic, showing both market and fractal market characteristics. Price fluctuation is not only influenced by the internal market mechanism, but is also impacted by the heterogeneous environment. Finally, we provide suggestions for regulation and development of carbon market.

  2. Two New Families of Lanthanide Mixed-Ligand Complexes, Oxalate-Carbonate and Oxalate-Formate: Synthesis and Structure of [Ce(H 2O)] 2(C 2O 4) 2(CO 3)·2.5 H 2O and Ce(C 2O 4)(HCO 2)

    Science.gov (United States)

    Romero, S.; Mosset, A.; Trombe, J. C.

    1996-12-01

    Two new families of lanthanide complexes associating the ligands oxalate and carbonate or oxalate and formate have been prepared under autogenous pressure at 200°C using a pseudo-hydrothermal method. The two families have been extended to some lanthanides ( Ln): oxalate-carbonate Ln= Ce, Pr, Nd, and Eu; oxalate-formate Ln= La, Ce, and Sm. The starting suspension contains either oxalate or a mixture of oxalate and oxalic acid. The structures have been solved for the element cerium. In both cases, the structure is built up from cerium atoms sharing all their oxygen atoms with oxalate and carbonate or oxalate and formate ligands, thus forming a three-dimensional network. The cerium polyhedra share either faces or edges or corners. The coordination scheme of the oxalate ligands is variable: bischelating, bischelating and monodentate, or bischelating and bismonodentate. The carbonate group acts as a bischelating and bismonodentate ligand while the formate group is chelating and monodentate. The characterization of these two original families by infrared spectra and thermal behavior is presented for some pure phases. A tentative explanation of the synthesis of these two phases will be emphasized.

  3. Carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    The document identifies the main sources of carbon monoxide (CO) in the general outdoor atmosphere, describes methods of measuring and monitoring its concentration levels in the United Kingdom, and discusses the effects of carbon monoxide on human health. Following its review, the Panel has put forward a recommendation for an air quality standard for carbon monoxide in the United Kingdom of 10 ppm, measured as a running 8-hour average. The document includes tables and graphs of emissions of CO, in total and by emission source, and on the increase in blood levels of carboxyhaemoglobin with continuing exposure to CO. 11 refs., 4 figs., 4 tabs.

  4. Structural Control of (1)A(2u)-to-(3)A(2u) Intersystem Crossing in Diplatinum(II,II) Complexes

    Czech Academy of Sciences Publication Activity Database

    Durrell, A. C.; Keller, G. E.; Lam, Y.; Ch.; Sýkora, Jan; Vlček, Antonín; Gray, H. B.

    2012-01-01

    Roč. 134, č. 34 (2012), s. 14201-14207 ISSN 0002-7863 R&D Projects: GA MŠk(CZ) ME10124 Institutional support: RVO:61388955 Keywords : TRIPLET EXCITED-STATE * BINUCLEAR PLATINUM(II) PHOTOCHEMISTRY * ELECTRON-TRANSFER REACTIONS Subject RIV: CG - Electrochemistry Impact factor: 10.677, year: 2012

  5. The Bio-accessibility of Synthetic Fe-Organo Complexes in Subsurface Soil with Elevated Temperature: a Proxy for the Vulnerability of Mineral Associated Carbon to Warming Rachel C. Porras, Peter S. Nico, and Margaret Torn Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA

    Science.gov (United States)

    Porras, R. C.; Hicks Pries, C.

    2015-12-01

    Globally, subsurface soils (>30 cm) represent an important reservoir of soil organic carbon (SOC). However, the vulnerability of this deep SOC and, in particular mineral-associated SOC, to warming, and its potential to amplify the effects of climate change is highly uncertain. To gain insight into the bio-accessibility and temperature sensitivity of mineral-associated organic C, we conducted a series of incubations using soils collected from three depths (0-10, 50-60, and 80-90 cm) under coniferous forest. The soils are moderately acidic (mean pH=6.5) sandy, mixed, mesic Ultic Haploxeralfs. To understand how mechanisms controlling SOC bio-accessibilty or temperature sensitivity differ with depth and with the properties of Fe-organo complexes (i.e.,degree of crystallinity, amount of reactive surface area, or surface saturation), we used a 13C labeled glucose substrate to prepare synthetic Fe-organo complexes spanning a range of crystallinity and mineral surface saturation. The synthetic Fe-organo complexes were then added to soil from three depths. The soils containing the 13C labeled Fe-organo adduct were incubated at two temperatures (ambient and +4°C) and respired 13CO2 was measured and used to estimate flux rates. Differences in measured 13CO2 fluxes as a function of depth, surface loading, and mineral properties are discussed in terms of their implications for the temperature sensitivity of mineral protected organic carbon in subsurface soils.

  6. High-Melt Carbon-Carbon Coating for Nozzle Extensions

    Science.gov (United States)

    Thompson, James

    2015-01-01

    Carbon-Carbon Advanced Technologies, Inc. (C-CAT), has developed a high-melt coating for use in nozzle extensions in next-generation spacecraft. The coating is composed primarily of carbon-carbon, a carbon-fiber and carbon-matrix composite material that has gained a spaceworthy reputation due to its ability to withstand ultrahigh temperatures. C-CAT's high-melt coating embeds hafnium carbide (HfC) and zirconium diboride (ZrB2) within the outer layers of a carbon-carbon structure. The coating demonstrated enhanced high-temperature durability and suffered no erosion during a test in NASA's Arc Jet Complex. (Test parameters: stagnation heat flux=198 BTD/sq ft-sec; pressure=.265 atm; temperature=3,100 F; four cycles totaling 28 minutes) In Phase I of the project, C-CAT successfully demonstrated large-scale manufacturability with a 40-inch cylinder representing the end of a nozzle extension and a 16-inch flanged cylinder representing the attach flange of a nozzle extension. These demonstrators were manufactured without spalling or delaminations. In Phase II, C-CAT worked with engine designers to develop a nozzle extension stub skirt interfaced with an Aerojet Rocketdyne RL10 engine. All objectives for Phase II were successfully met. Additional nonengine applications for the coating include thermal protection systems (TPS) for next-generation spacecraft and hypersonic aircraft.

  7. Calcium Carbonate

    Science.gov (United States)

    ... Calcium is needed by the body for healthy bones, muscles, nervous system, and heart. Calcium carbonate also ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

  8. Complex analysis

    CERN Document Server

    Freitag, Eberhard

    2005-01-01

    The guiding principle of this presentation of ``Classical Complex Analysis'' is to proceed as quickly as possible to the central results while using a small number of notions and concepts from other fields. Thus the prerequisites for understanding this book are minimal; only elementary facts of calculus and algebra are required. The first four chapters cover the essential core of complex analysis: - differentiation in C (including elementary facts about conformal mappings) - integration in C (including complex line integrals, Cauchy's Integral Theorem, and the Integral Formulas) - sequences and series of analytic functions, (isolated) singularities, Laurent series, calculus of residues - construction of analytic functions: the gamma function, Weierstrass' Factorization Theorem, Mittag-Leffler Partial Fraction Decomposition, and -as a particular highlight- the Riemann Mapping Theorem, which characterizes the simply connected domains in C. Further topics included are: - the theory of elliptic functions based on...

  9. Infiltrated carbon foam composites

    Science.gov (United States)

    Lucas, Rick D. (Inventor); Danford, Harry E. (Inventor); Plucinski, Janusz W. (Inventor); Merriman, Douglas J. (Inventor); Blacker, Jesse M. (Inventor)

    2012-01-01

    An infiltrated carbon foam composite and method for making the composite is described. The infiltrated carbon foam composite may include a carbonized carbon aerogel in cells of a carbon foam body and a resin is infiltrated into the carbon foam body filling the cells of the carbon foam body and spaces around the carbonized carbon aerogel. The infiltrated carbon foam composites may be useful for mid-density ablative thermal protection systems.

  10. Subgroup complexes

    CERN Document Server

    Smith, Stephen D

    2011-01-01

    This book is intended as an overview of a research area that combines geometries for groups (such as Tits buildings and generalizations), topological aspects of simplicial complexes from p-subgroups of a group (in the spirit of Brown, Quillen, and Webb), and combinatorics of partially ordered sets. The material is intended to serve as an advanced graduate-level text and partly as a general reference on the research area. The treatment offers optional tracks for the reader interested in buildings, geometries for sporadic simple groups, and G-equivariant equivalences and homology for subgroup complexes.

  11. Complex manifolds

    CERN Document Server

    Morrow, James

    2006-01-01

    This book, a revision and organization of lectures given by Kodaira at Stanford University in 1965-66, is an excellent, well-written introduction to the study of abstract complex (analytic) manifolds-a subject that began in the late 1940's and early 1950's. It is largely self-contained, except for some standard results about elliptic partial differential equations, for which complete references are given. -D. C. Spencer, MathSciNet The book under review is the faithful reprint of the original edition of one of the most influential textbooks in modern complex analysis and geometry. The classic

  12. Cisplatin carbonato complexes. Implications for uptake, antitumor properties, and toxicity.

    Science.gov (United States)

    Centerwall, Corey R; Goodisman, Jerry; Kerwood, Deborah J; Dabrowiak, James C

    2005-09-21

    The reaction of aquated cisplatin with carbonate which is present in culture media and blood is described. The first formed complex is a monochloro monocarbonato species, which upon continued exposure to carbonate slowly forms a biscarbonato complex. The formation of carbonato species under conditions that simulate therapy may have important implications for uptake, antitumor properties, and toxicity of cisplatin.

  13. Complex Networks

    CERN Document Server

    Evsukoff, Alexandre; González, Marta

    2013-01-01

    In the last decade we have seen the emergence of a new inter-disciplinary field focusing on the understanding of networks which are dynamic, large, open, and have a structure sometimes called random-biased. The field of Complex Networks is helping us better understand many complex phenomena such as the spread of  deseases, protein interactions, social relationships, to name but a few. Studies in Complex Networks are gaining attention due to some major scientific breakthroughs proposed by network scientists helping us understand and model interactions contained in large datasets. In fact, if we could point to one event leading to the widespread use of complex network analysis is the availability of online databases. Theories of Random Graphs from Erdös and Rényi from the late 1950s led us to believe that most networks had random characteristics. The work on large online datasets told us otherwise. Starting with the work of Barabási and Albert as well as Watts and Strogatz in the late 1990s, we now know th...

  14. Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(II) and platinum(II) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus.

    Science.gov (United States)

    Fernández-Anca, Damián; García-Seijo, M Inés; García-Fernández, M Esther

    2010-03-07

    The reaction of NP(3) (tris[2-(diphenylphosphino)ethyl]amine and PP(3) (tris[2-(diphenylphosphino)ethyl]phosphine) with the five-coordinate complexes [PdCl(NP(3))]Cl (1) and [MX(PP(3))]X [M = Pd: X = Cl(2), Br(3), I(4); M = Pt: X = Cl(5), Br(6), I(7)], respectively, followed by (31)P{(1)H}NMR when X = Cl, led to the formation of unprecedented four-coordinate halides in a 1 : 2 metal to ligand ratio, [M(AP(3))(2)]X(2) [A = N, M = Pd: X = Cl(8); A = P, M = Pd: X = Cl(9), Br(10), I(11); A = P, M = Pt: X = Cl(12), Br(13), I (14)], containing reactive dangling phosphorus. Given the non characterised precursors [M(ONO(2))(PP(3))](NO(3))], the interaction between the heteronuclear species [MAg(NO(3))(3)(PP(3))] [M = Pd(15), Pt(16)] and PP(3) was explored. It was found that the addition of 1 equivalent of phosphine afforded [MAg(NO(3))(PP(3))(2)](NO(3))(2) [M = Pd(15*), Pt(16*)] containing Ag(I) bound to two dangling phosphorus while the reaction with 2 equivalents led to the complexes [M(PP(3))(2)](NO(3))(2) [M = Pd (17), Pt (18)] in coexistence with [Ag(2)(mu-PP(3))(2)](NO(3))(2). The fate of Ag(I) on the reaction of the mixed metal compounds with excess PP(3) consisted of preventing dissociation, observed in solution for halides, and acting as an assistant for crystallization. Colourless single crystals of 18 and 10, studied by X-ray diffraction, were afforded by reaction of 16 with 4 equivalents of PP(3) and from solutions of 10 in chloroform coexisting with red crystals of 3, respectively. The structures revealed the presence of dications [M(PP(3))(2)](2+) that show two five-membered chelate rings to M(II) in a square-planar arrangement and four uncoordinated phosphine arms with the counter anions being symmetrically placed at 4.431 (Br(-)) and 13.823 (NO(3)(-)) A from M(II) above and below its coordination, MP(4), plane. Complexes 9 and 12 were shown to undergo an interesting reactivity in solution versus group 11 monocations. The reactions consisted of conversions

  15. Electron irradiation of carbon dioxide-carbon disulphide ice analog ...

    Indian Academy of Sciences (India)

    les and the reactions where they take part in making the complex molecules were studied in laboratory simu- lations in both the gas and ice phase.1 Indeed, in such experimental simulations it is observed that several other carbon and sulphur bearing molecules, so far not reported to be present in the ISM, were also synthe-.

  16. Carbon sequestration.

    Science.gov (United States)

    Lal, Rattan

    2008-02-27

    Developing technologies to reduce the rate of increase of atmospheric concentration of carbon dioxide (CO2) from annual emissions of 8.6PgCyr-1 from energy, process industry, land-use conversion and soil cultivation is an important issue of the twenty-first century. Of the three options of reducing the global energy use, developing low or no-carbon fuel and sequestering emissions, this manuscript describes processes for carbon (CO2) sequestration and discusses abiotic and biotic technologies. Carbon sequestration implies transfer of atmospheric CO2 into other long-lived global pools including oceanic, pedologic, biotic and geological strata to reduce the net rate of increase in atmospheric CO2. Engineering techniques of CO2 injection in deep ocean, geological strata, old coal mines and oil wells, and saline aquifers along with mineral carbonation of CO2 constitute abiotic techniques. These techniques have a large potential of thousands of Pg, are expensive, have leakage risks and may be available for routine use by 2025 and beyond. In comparison, biotic techniques are natural and cost-effective processes, have numerous ancillary benefits, are immediately applicable but have finite sink capacity. Biotic and abiotic C sequestration options have specific nitches, are complementary, and have potential to mitigate the climate change risks.

  17. A neodymium(III)-ammonium complex involving oxalate and carbonate ligands: (NH4)2[Nd2(C2O4)3(CO3)(H2O)].H2O.

    Science.gov (United States)

    Trombe, Jean-Christian; Galy, Jean; Enjalbert, Renée

    2002-10-01

    The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

  18. Managing Complexity

    Energy Technology Data Exchange (ETDEWEB)

    Chassin, David P.; Posse, Christian; Malard, Joel M.

    2004-08-01

    Physical analogs have shown considerable promise for understanding the behavior of complex adaptive systems, including macroeconomics, biological systems, social networks, and electric power markets. Many of today’s most challenging technical and policy questions can be reduced to a distributed economic control problem. Indeed, economically-based control of large-scale systems is founded on the conjecture that the price-based regulation (e.g., auctions, markets) results in an optimal allocation of resources and emergent optimal system control. This paper explores the state of the art in the use physical analogs for understanding the behavior of some econophysical systems and to deriving stable and robust control strategies for them. In particular we review and discussion applications of some analytic methods based on the thermodynamic metaphor according to which the interplay between system entropy and conservation laws gives rise to intuitive and governing global properties of complex systems that cannot be otherwise understood.

  19. Carbon nanomaterials in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Pu Chun Ke [Laboratory of Single-Molecule Biophysics and Polymer Physics, Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Qiao Rui [Department of Mechanical Engineering, Clemson University, Clemson, SC 29634 (United States)

    2007-09-19

    This paper intends to reflect, from the biophysical viewpoint, our current understanding on interfacing nanomaterials, such as carbon nanotubes and fullerenes, with biological systems. Strategies for improving the solubility, and therefore, the bioavailability of nanomaterials in aqueous solutions are summarized. In particular, the underlining mechanisms of attaching biomacromolecules (DNA, RNA, proteins) and lysophospholipids onto carbon nanotubes and gallic acids onto fullerenes are analyzed. The diffusion and the cellular delivery of RNA-coated carbon nanotubes are characterized using fluorescence microscopy. The translocation of fullerenes across cell membranes is simulated using molecular dynamics to offer new insight into the complex issue of nanotoxicity. To assess the fate of nanomaterials in the environment, the biomodification of lipid-coated carbon nanotubes by the aquatic organism Daphnia magna is discussed. The aim of this paper is to illuminate the need for adopting multidisciplinary approaches in the field study of nanomaterials in biological systems and in the environment. (topical review)

  20. Carbon nanomaterials in biological systems

    International Nuclear Information System (INIS)

    Pu Chun Ke; Qiao Rui

    2007-01-01

    This paper intends to reflect, from the biophysical viewpoint, our current understanding on interfacing nanomaterials, such as carbon nanotubes and fullerenes, with biological systems. Strategies for improving the solubility, and therefore, the bioavailability of nanomaterials in aqueous solutions are summarized. In particular, the underlining mechanisms of attaching biomacromolecules (DNA, RNA, proteins) and lysophospholipids onto carbon nanotubes and gallic acids onto fullerenes are analyzed. The diffusion and the cellular delivery of RNA-coated carbon nanotubes are characterized using fluorescence microscopy. The translocation of fullerenes across cell membranes is simulated using molecular dynamics to offer new insight into the complex issue of nanotoxicity. To assess the fate of nanomaterials in the environment, the biomodification of lipid-coated carbon nanotubes by the aquatic organism Daphnia magna is discussed. The aim of this paper is to illuminate the need for adopting multidisciplinary approaches in the field study of nanomaterials in biological systems and in the environment. (topical review)

  1. Method for the preparation of carbon fiber from polyolefin fiber precursor

    Energy Technology Data Exchange (ETDEWEB)

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2017-11-28

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  2. Complex variables

    CERN Document Server

    Flanigan, Francis J

    2010-01-01

    A caution to mathematics professors: Complex Variables does not follow conventional outlines of course material. One reviewer noting its originality wrote: ""A standard text is often preferred [to a superior text like this] because the professor knows the order of topics and the problems, and doesn't really have to pay attention to the text. He can go to class without preparation."" Not so here-Dr. Flanigan treats this most important field of contemporary mathematics in a most unusual way. While all the material for an advanced undergraduate or first-year graduate course is covered, discussion

  3. Bilan CarboneR - Implementation

    International Nuclear Information System (INIS)

    Wolff, Aurelie

    2015-01-01

    Bilan Carbone TM , a method for calculating greenhouse gas emissions, was developed to help companies and territorial authorities estimate emissions from their activities or on their territories. After validating the audit perimeter and determining the emission categories to be taken into account, activity data is collected and greenhouse gas emissions are calculated using the tool. Besides accounting greenhouse gas emissions at any given time, the inventory evaluates impact on climate and energy dependence. This helps organizations deal with their emissions by classifying them, implementing action plans to reduce emissions and starting a dynamic process taking into account carbon in their strategic decisions

  4. Complex dynamics

    CERN Document Server

    Carleson, Lennart

    1993-01-01

    Complex dynamics is today very much a focus of interest. Though several fine expository articles were available, by P. Blanchard and by M. Yu. Lyubich in particular, until recently there was no single source where students could find the material with proofs. For anyone in our position, gathering and organizing the material required a great deal of work going through preprints and papers and in some cases even finding a proof. We hope that the results of our efforts will be of help to others who plan to learn about complex dynamics and perhaps even lecture. Meanwhile books in the field a. re beginning to appear. The Stony Brook course notes of J. Milnor were particularly welcome and useful. Still we hope that our special emphasis on the analytic side will satisfy a need. This book is a revised and expanded version of notes based on lectures of the first author at UCLA over several \\Vinter Quarters, particularly 1986 and 1990. We owe Chris Bishop a great deal of gratitude for supervising the production of cour...

  5. Cosmic Complexity

    Science.gov (United States)

    Mather, John C.

    2012-01-01

    What explains the extraordinary complexity of the observed universe, on all scales from quarks to the accelerating universe? My favorite explanation (which I certainty did not invent) ls that the fundamental laws of physics produce natural instability, energy flows, and chaos. Some call the result the Life Force, some note that the Earth is a living system itself (Gaia, a "tough bitch" according to Margulis), and some conclude that the observed complexity requires a supernatural explanation (of which we have many). But my dad was a statistician (of dairy cows) and he told me about cells and genes and evolution and chance when I was very small. So a scientist must look for me explanation of how nature's laws and statistics brought us into conscious existence. And how is that seemll"!gly Improbable events are actually happening a!1 the time? Well, the physicists have countless examples of natural instability, in which energy is released to power change from simplicity to complexity. One of the most common to see is that cooling water vapor below the freezing point produces snowflakes, no two alike, and all complex and beautiful. We see it often so we are not amazed. But physlc!sts have observed so many kinds of these changes from one structure to another (we call them phase transitions) that the Nobel Prize in 1992 could be awarded for understanding the mathematics of their common features. Now for a few examples of how the laws of nature produce the instabilities that lead to our own existence. First, the Big Bang (what an insufficient name!) apparently came from an instability, in which the "false vacuum" eventually decayed into the ordinary vacuum we have today, plus the most fundamental particles we know, the quarks and leptons. So the universe as a whole started with an instability. Then, a great expansion and cooling happened, and the loose quarks, finding themselves unstable too, bound themselves together into today's less elementary particles like protons and

  6. Carbonizing process

    Energy Technology Data Exchange (ETDEWEB)

    1923-11-22

    In the downward distillation of coal, shale, lignite, or the like, the heat is generated by the combustion of liquid or gaseous fuel above the charge the zone of carbonization thus initiated travelling downwards through the charge. The combustible gases employed are preferably those resulting from the process but gases such as natural gas may be employed. The charge is in a moistened and pervious state the lower parts being maintained at a temperature not above 212/sup 0/F until influenced by contact with the carbonization zone and steam may be admitted to increase the yield of ammonia. The combustible gases may be supplied with insufficient air so as to impart to them a reducing effect.

  7. Carbon aerogels

    International Nuclear Information System (INIS)

    Berthon-Fabry, S.; Achard, P.

    2003-06-01

    The carbon aerogel is a nano-porous material at open porosity, electrical conductor. The aerogels morphology is variable in function of the different synthesis parameters. This characteristic offers to the aerogels a better adaptability to many applications: electrodes (super condensers, fuel cells). The author presents the materials elaboration and their applications. It provides also the research programs: fundamental research, realization of super-condenser electrodes, fuel cells electrodes, gas storage materials and opaque materials for thermal insulation. (A.L.B.)

  8. State forestry agency perspectives on carbon management and carbon market assistance to family forest owners

    Science.gov (United States)

    Kristell A. Miller; Stephanie A. Snyder; Michael A. Kilgore

    2015-01-01

    Family forest owners within the United States could potentially make significant contributions to sequestration efforts. However, we expect that landowners will need assistance if they are to successfully implement carbon management techniques and/or navigate through complex carbon market requirements. State forestry agencies were surveyed to gather their perspectives...

  9. Insight into the toxic effects of cis-dichloridoplatinum(II) complexes containing 7-azaindole halogeno derivatives in tumor cells

    Czech Academy of Sciences Publication Activity Database

    Muchová, T.; Prachařová, J.; Štarha, P.; Olivová, R.; Vrána, Oldřich; Benešová, B.; Kašpárková, J.; Trávníček, Z.; Brabec, Viktor

    2013-01-01

    Roč. 18, č. 5 (2013), s. 579-589 ISSN 0949-8257 R&D Projects: GA ČR(CZ) GAP301/10/0598; GA MŠk(CZ) LH13096 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : CELLULAR-RESPONSE * LUNG - CANCER * PLATINUM(II) Subject RIV: BO - Biophysics Impact factor: 3.164, year: 2013

  10. Thermodynamic and kinetic studies of the equilibration reaction between the sulfur and carbon bonded forms of a cobalt(III) complex with the ligands 2-aminoethyl-3-aminopropylsulfide and 1,1,1-tris(aminomethyl)ethane

    DEFF Research Database (Denmark)

    Springborg, J.; Kjellerup, S.; Kofod, Pauli

    1996-01-01

    -thia-hexan-4-ide anion). Kinetic and thermodn. data were obtained using UV-visible spectroscopy, IE-HPLC and 13C NMR ([OH-] = 4 * 10-5-1.0 M, T = 25.0-100 Deg, I = 1.0 M). The kinetic data were interpreted in terms of different reactivity of ion pairs with perchlorate and hydroxide, resp. Rate consts....... and activation parameters for the formation of the Co-alkyl complex from ion pairs with perchlorate and hydroxide, resp. (composite terms), and for the reformation of the Co-S complex from ion pairs with perchlorate are given, together with thermodn. data. The data were interpreted in terms of the intermediate...

  11. Society and the Carbon Cycle: A Social Science Perspective

    Science.gov (United States)

    Romero-Lankao, P.

    2017-12-01

    Societal activities, actions, and practices affect the carbon cycle and the climate of North America in complex ways. Carbon is a key component for the functioning of croplands, grasslands, forests. Carbon fuels our industry, transportation (vehicles and roadways), buildings, and other structures. Drawing on results from the SOCCR-2, this presentation uses a social science perspective to address three scientific questions. How do human actions and activities affect the carbon cycle? How human systems such as cities, agricultural field and forests are affected by changes in the carbon cycle? How is carbon management enabled and constraint by socio-political dynamics?

  12. Carbon cycle

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, J; Halbritter, G; Neumann-Hauf, G

    1982-05-01

    This report contains a review of literature on the subjects of the carbon cycle, the increase of the atmospheric CO/sub 2/ concentration and the possible impacts of an increased CO/sub 2/ concentration on the climate. In addition to this survey, the report discusses the questions that are still open and the resulting research needs. During the last twenty years a continual increase of the atmospheric carbon dioxide concentration by about 1-2 ppm per years has been observed. In 1958 the concentration was 315 ppm and this increased to 336 ppm in 1978. A rough estimate shows that the increase of the atmospheric carbon dioxide concentration is about half of the amount of carbon dioxide added to the atmosphere by the combustion of fossil fuels. Two possible sinks for the CO/sub 2/ released into the atmosphere are known: the ocean and the biota. The role of the biota is, however, unclear, since it can act both as a sink and as a source. Most models of the carbon cycle are one-dimensional and cannot be used for accurate predictions. Calculations with climate models have shown that an increased atmospheric CO/sub 2/ concentration leads to a warming of the earth's surface and lower atmosphere. Calculations show that a doubling of the atmospheric CO/sub 2/-concentration would lead to a net heating of the lower atmosphere and earth's surface by a global average of about 4 W m/sup -2/. Greater uncertainties arise in estimating the change in surface temperature resulting from this change in heating rate. It is estimated that the global average annual surface temperature would change between 1.5 and 4.5 K. There are, however, latitudinal and seasonal variations of the impact of increased CO/sub 2/ concentration. Other meteorological variables (e.g. precipitation, wind speed etc.) would also be changed. It appears that the impacts of the other products of fossil fuel combustion are unlikely to counteract the impacts of CO/sub 2/ on the climate.

  13. Carbons and carbon supported catalysts in hydroprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, Edward

    2009-07-01

    This book is a comprehensive summary of recent research in the field and covers all areas of carbons and carbon materials. The potential application of carbon supports, particularly those of carbon black (CB) and activated carbon (AC) in hydroprocessing catalysis are covered. Novel carbon materials such as carbon fibers and carbon nano tubes (CNT) are also covered, including the more recent developments in the use of fullerenes in hydroprocessing applications. Although the primary focus of this book is on carbons and carbon supported catalysts, it also identifies the difference in the effect of carbon supports compared with the oxidic supports, particularly that of the Al{sub 2}O{sub 3}. The difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon supported catalysts are also comprehensively covered and include various methods of pretreatment of carbon supports to enhance catalyst performance. The model compounds results consistently show higher hydrodesulfurization and hydrodeoxygenation activities of carbon supported catalysts than that of the Al{sub 2}O{sub 3} supported catalysts. Also, the deactivation of the former catalysts by coke deposition was much less evident. Chapter 6.3.1.3 is on carbon-supported catalysts: coal-derived liquids.

  14. Carbon classified?

    DEFF Research Database (Denmark)

    Lippert, Ingmar

    2012-01-01

    . Using an actor- network theory (ANT) framework, the aim is to investigate the actors who bring together the elements needed to classify their carbon emission sources and unpack the heterogeneous relations drawn on. Based on an ethnographic study of corporate agents of ecological modernisation over...... a period of 13 months, this paper provides an exploration of three cases of enacting classification. Drawing on ANT, we problematise the silencing of a range of possible modalities of consumption facts and point to the ontological ethics involved in such performances. In a context of global warming...

  15. Carbon Footprints

    OpenAIRE

    Rahel Aichele; Gabriel Felbermayr

    2011-01-01

    Lässt sich der Beitrag eines Landes zum weltweiten Klimaschutz an der Veränderung seines CO2-Ausstoßes messen, wie es im Kyoto-Abkommen implizit unterstellt wird? Oder ist aufgrund der Bedeutung des internationalen Güterhandels der Carbon Footprint – der alle CO2-Emissionen erfasst, die durch die Absorption (d.h. Konsum und Investitionen) eines Landes entstehen – das bessere Maß? Die Autoren erstellen eine Datenbank mit den Footprints von 40 Ländern für den Zeitraum 1995–2007. Die deskriptive...

  16. The foil equilibration method for carbon in sodium

    Energy Technology Data Exchange (ETDEWEB)

    Borgstedt, H; Frees, G; Peric, Z [Karlsruhe Nuclear Research Center, Institute of Materials and Solid State Research, Karlsruhe (Germany)

    1980-05-01

    Among the non-metallic impurities in sodium, carbon plays an important role since at high temperatures the structural materials exposed to sodium are subject to carburization and decarburization depending on the carbon activity of the sodium. Carburization of austenitic stainless steels leads to reduction in ductility and fatigue properties whereas decarburization results in a decrease in the high temperature creep strength. A knowledge of the carbon activities in sodium will help understanding of the carbon transfer phenomena in operating sodium systems of the fast reactors, and also carbon diffusion, microstructural stability and mechanical behaviour of materials under different service conditions. An understanding of the carbon behaviour in sodium becomes difficult in view of the complexities of the different species present as elemental carbon, carbide, acetylide, carbonate, and cyanide. Carbon estimation techniques for sodium presently in use are: chemical analytical methods, on-line carbon monitors, and oil equilibration method. Various chemical methods have been developed for the estimation of different species like acetylide, cyanide, carbonate, elemental carbon, and total carbon in sodium. All these methods are time consuming and subject to various errors. The on-line monitors developed for carbon in sodium are able to give continuous indication of carbon activities and have higher sensitivity than the chemical methods. A still more simple method for the determination of carbon activities is by the foil equilibration first published by Natesan et al. Because of its simplicity like the vanadium wire equilibration for oxygen it is being used widely for the estimation of carbon activities in sodium systems. Carbon concentrations in operating sodium systems estimated by this procedure by applying solubility relation to carbon activities have yielded very low values of carbon, lower than the sensitivity limits of the chemical estimation methods. Foil

  17. The foil equilibration method for carbon in sodium

    International Nuclear Information System (INIS)

    Borgstedt, H.; Frees, G.; Peric, Z.

    1980-01-01

    Among the non-metallic impurities in sodium, carbon plays an important role since at high temperatures the structural materials exposed to sodium are subject to carburization and decarburization depending on the carbon activity of the sodium. Carburization of austenitic stainless steels leads to reduction in ductility and fatigue properties whereas decarburization results in a decrease in the high temperature creep strength. A knowledge of the carbon activities in sodium will help understanding of the carbon transfer phenomena in operating sodium systems of the fast reactors, and also carbon diffusion, microstructural stability and mechanical behaviour of materials under different service conditions. An understanding of the carbon behaviour in sodium becomes difficult in view of the complexities of the different species present as elemental carbon, carbide, acetylide, carbonate, and cyanide. Carbon estimation techniques for sodium presently in use are: chemical analytical methods, on-line carbon monitors, and oil equilibration method. Various chemical methods have been developed for the estimation of different species like acetylide, cyanide, carbonate, elemental carbon, and total carbon in sodium. All these methods are time consuming and subject to various errors. The on-line monitors developed for carbon in sodium are able to give continuous indication of carbon activities and have higher sensitivity than the chemical methods. A still more simple method for the determination of carbon activities is by the foil equilibration first published by Natesan et al. Because of its simplicity like the vanadium wire equilibration for oxygen it is being used widely for the estimation of carbon activities in sodium systems. Carbon concentrations in operating sodium systems estimated by this procedure by applying solubility relation to carbon activities have yielded very low values of carbon, lower than the sensitivity limits of the chemical estimation methods. Foil

  18. Simultaneous voltammetric determination of dopamine and ascorbic acid using multivariate calibration methodology performed on a carbon paste electrode modified by a mer-[RuCl3(dppb)(4-pic)] complex

    International Nuclear Information System (INIS)

    Santos, Poliana M.; Sandrino, Bianca; Moreira, Tiago F.; Wohnrath, Karen; Nagata, Noemi; Pessoa, Christiana A.

    2007-01-01

    The preparation and electrochemical characterization of a carbon paste electrode (CPE) modified with mer-[Ru0Cl 3 (dppb)(4-pic)] (dppb=Ph 2 P(CH 2 ) 4 PPh 2 , 4-pic=CH 3 C 5 H 4 N), referred to as Rupic, were investigated. The CPE/Rupic system displayed only one pair of redox peaks, with a midpoint potential at 0.28 V vs. Ag/AgCl, which were ascribed to Ru III /Ru II charge transfer. This modified electrode presented the property of electrocatalysing the oxidation of dopamine (DA) and ascorbic acid (AA) at 0.35 V and 0.30 V vs. Ag/AgCl, respectively. Because the oxidation for both AA and DA practically occurred at the same potential, distinguishing between them was difficult with cyclic voltammetry. This limitation was overcome using Partial Least Square Regression (PLSR), which allowed us, with the optimised models, to determine four synthetic samples with prediction errors (RMSEP) of 5.55 X 10 -5 mol L -1 and 7.48 X 10 -6 mol L -1 for DA and AA, respectively. (author)

  19. Simultaneous voltammetric determination of dopamine and ascorbic acid using multivariate calibration methodology performed on a carbon paste electrode modified by a mer-[RuCl{sub 3}(dppb)(4-pic)] complex

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Poliana M.; Sandrino, Bianca; Moreira, Tiago F.; Wohnrath, Karen; Nagata, Noemi; Pessoa, Christiana A. [Universidade Estadual de Ponta Grossa, PR (Brazil). Dept. de Quimica]. E-mail: capessoa@uepg.br

    2007-07-01

    The preparation and electrochemical characterization of a carbon paste electrode (CPE) modified with mer-[Ru0Cl{sub 3}(dppb)(4-pic)] (dppb=Ph{sub 2}P(CH{sub 2}){sub 4}PPh{sub 2}, 4-pic=CH{sub 3}C{sub 5}H{sub 4}N), referred to as Rupic, were investigated. The CPE/Rupic system displayed only one pair of redox peaks, with a midpoint potential at 0.28 V vs. Ag/AgCl, which were ascribed to Ru{sup III}/Ru{sup II} charge transfer. This modified electrode presented the property of electrocatalysing the oxidation of dopamine (DA) and ascorbic acid (AA) at 0.35 V and 0.30 V vs. Ag/AgCl, respectively. Because the oxidation for both AA and DA practically occurred at the same potential, distinguishing between them was difficult with cyclic voltammetry. This limitation was overcome using Partial Least Square Regression (PLSR), which allowed us, with the optimised models, to determine four synthetic samples with prediction errors (RMSEP) of 5.55 X 10{sup -5} mol L{sup -1} and 7.48 X 10{sup -6} mol L{sup -1} for DA and AA, respectively. (author)

  20. Aqueous complexes of lanthanides(III) and actinides(III) with the carbonate and sulphate ions. Thermodynamic study by time-resolved laser-induced fluorescence spectroscopy and electro-spray-ionisation mass spectrometry

    International Nuclear Information System (INIS)

    Vercouter, Th.

    2005-03-01

    The prediction of the environmental impact of a possible geological disposal of radioactive wastes is supported by the thermodynamic modelling of the radionuclides behaviour in the groundwater. In this framework, the analogy between lanthanides and actinides(III) is confirmed by a critical analysis of the literature and the comparison with experimental results obtained here. The limiting complex, Eu(CO 3 ) 3 3- , is identified by solubility measurements in Na 2 CO 3 solutions. Then the formation constants of the complexes Eu(CO 3 ) i 3-2i (i=1-3) and Eu(SO 4 ) i 3-2i (i=1-2) are measured by TRLFS. The formation of aqueous LaSO 4 + is studied by ESI-MS and is in good agreement with the expected speciation. The enthalpy and entropy of the reaction Cm(CO 3 ) 2 - + CO 3 2- ↔ Cm(CO 3 ) 3 3- are deduced from TRLFS measurements of the equilibrium constant between 10 and 70 C. The ionic strength effect is calculated using the SIT formula. (author)

  1. Gadolinium DTPA-monoamide complexes incorporated into mixed micelles as possible MRI contrast agents

    OpenAIRE

    Parac-Vogt, Tatjana; Kimpe, Kristof; Laurent, Sophie; Pierart, Corinne; Vander Elst, Luce; Muller, Robert N.; Binnemans, Koen

    2004-01-01

    Four monoamide derivatives of Gd-DTPA with alkyl chains consisting of 12, 14, 16, or 18 carbon atoms were synthesized. The gadolinium(III) complexes with chain lengths of 14, 16 or 18 carbon atoms were efficiently incorporated into mixed micelles whereas the complex with a chain length of 12 carbon atoms was not incorporated into a micellar structure. The size distribution of the micelles was measured by photon correlation spectroscopy. The mean sizes of the micelles for all the complexes lay...

  2. Soil, climate and the environment - an indissociable threesome. Soil carbon and global changes: reciprocal impacts; Carbon in all its forms; Echomicadas, a new tool to analyse carbon 14; Biotransformation of metallic trace elements by soil micro-organisms; Absorption and distribution of metallic elements in plants; Dynamics of metallic contaminants in agricultural systems; Is photo-remediation for tomorrow? Hyper-accumulator plants; Sediments, tell me the Seine history... The complex history of plant feeding by the soil; The environmental analysis

    International Nuclear Information System (INIS)

    Hatte, Christine; Tisnerat-Laborde, Nadine; Ayrault, Sophie; Balesdent, Jerome; Chapon, Virginie; Bourguignon, Jacques; Alban, Claude; Ravanel, Stephane; Denaix, Laurence; Nguyen, Christophe; Vavasseur, Alain; Sarrobert, Catherine; Gasperi, Johnny; Latrille, Christelle; Savoye, Sebastien; Augusto, Laurent; Conan Labbe, Annie; Bernard Michel, Bruno; Douysset, Guilhem; Toqnelli, Antoine; Vailhen, Dominique; Moulin, Christophe

    2016-01-01

    The articles of this file on the relationships between soils, climate and the environment discuss the reciprocal impacts of soil carbon and global changes with the objective of reduction of greenhouse effect and of increase of carbon sequestration; the various forms of carbon are presented and their properties commented ; a compact radiocarbon system (ECHoMiCADAS) is presented, developed by the Laboratory of sciences of climate and environment (LSCE) and designed for the analysis of carbon 14; an article describes how micro-organisms can play a crucial role in the transformation of soil pollutants by modifying their chemical speciation and thus their toxicity; strategies based on the absorption of metallic trace elements present in the soil to control physiological processes in plants are discussed, with applications to agriculture, food supply and to the environment; researches related to the study of effects of metallic contaminants in agricultural systems are evoked, and the reasons for a slow development of phyto-technologies, notably phyto-remediation, for pollution control and decontamination of soils and liquid media, are explained. Other themes are presented : hyper-accumulator plants which present very high contents of non-essential (As, Cd, Hg, Pb, Se) or essential (Co, Cu, Fe, Mn, Mo, Ni) elements, are slowly growing, and display a limited biomass, but could be used for a phyto-extraction of metals from contaminated soils; how analysis and dating of sediments can reveal the presence of contaminants, and therefore give an insight into human activities and regulations, and into their impact on the river; how plants are able to develop strategies in their search for nutrients in different types of soils, even poor ones, and presentation of the various disciplines, methods and techniques used for environmental analysis with their applications to installation and site control, or to the study of pollutant migration

  3. Mechanochemical treatment of amorphous carbon from brown sphagnum moss for the preparation of carbon nanotubes

    International Nuclear Information System (INIS)

    Onishchenko, D.V.

    2013-01-01

    Under consideration is the mechanism of multiwalled nanotubes formation during mechanical activation of amorphous carbon synthesized by pyrolysis of sphagnum moss. The formation of nanotubes has been shown to take place in the array of carbon particles. A complex study of the sorption characteristics of carbon nanotubes has been carried out. The dependence of the sorption capacity of carbon nanotubes on their storage time, as well as the effect of the process parameters of nanotubes formation on their ability for oxidative modification, is represented. (authors)

  4. Carbon Nanotubes: Molecular Electronic Components

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  5. Trading forest carbon

    Science.gov (United States)

    The nature of carbon in forests is discussed from the perspective of carbon trading. Carbon inventories, specifically in the area of land use and forestry are reviewed for the Pacific Northwest. Carbon turnover in forests is discussed as it relates to carbon sequestration. Scient...

  6. Production of precipitated calcium carbonate from calcium silicates and carbon dioxide

    International Nuclear Information System (INIS)

    Teir, Sebastian; Eloneva, Sanni; Zevenhoven, Ron

    2005-01-01

    The possibilities for reducing carbon dioxide emissions from the pulp and paper industry by calcium carbonation are presented. The current precipitated calcium carbonate (PCC) production uses mined, crushed calcium carbonate as raw materials. If calcium silicates were used instead, carbon dioxide emissions from the calcination of carbonates would be eliminated. In Finland, there could, thus, be a potential for eliminating 200 kt of carbon dioxide emissions per year, considering only the PCC used in the pulp and paper industry. A preliminary investigation of the feasibility to produce PCC from calcium silicates and the potential to replace calcium carbonate as the raw material was made. Calcium carbonate can be manufactured from calcium silicates by various methods, but only a few have been experimentally verified. The possibility and feasibility of these methods as a replacement for the current PCC production process was studied by thermodynamic equilibrium calculations using HSC software and process modelling using Aspen Plus[reg]. The results from the process modelling showed that a process that uses acetic acid for extraction of the calcium ions is a high potential option for sequestering carbon dioxide by mineral carbonation. The main obstacle seems to be the limited availability and relatively high price of wollastonite, which is a mineral with high calcium silicate content. An alternative is to use the more common, but also more complex, basalt rock instead

  7. Thiosemicarbazone complexes of the platinum metals. A story of ...

    Indian Academy of Sciences (India)

    Unknown

    Thiosemicarbazone complexes; platinum metals; variable coordination; ... carbonylic carbon via one or two intervening atoms, D,N,S tricoordination usually takes .... modelling studies show that in this coordination mode, the phenyl ring of the.

  8. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Education Centers Carbon Monoxide Information Center Carbon Monoxide Information Center En Español The Invisible Killer Carbon monoxide, ... Install one and check its batteries regularly. View Information About CO Alarms Other CO Topics Safety Tips ...

  9. Global Carbon Budget 2017

    NARCIS (Netherlands)

    Le Quere, Corinne; Andrew, Robbie M.; Friedlingstein, Pierre; Sitch, Stephen; Pongratz, Julia; Manning, Andrew C.; Korsbakken, Jan Ivar; Peters, Glen P.; Canadell, Josep G.; Jackson, Robert B.; Boden, Thomas A.; Tans, Pieter P.; Andrews, Oliver D.; Arora, Vivek K.; Bakker, Dorothee C. E.; Barbero, Leticia; Becker, Meike; Betts, Richard A.; Bopp, Laurent; Chevallier, Frederic; Chini, Louise P.; Ciais, Philippe; Cosca, Catherine E.; Cross, Jessica; Currie, Kim; Gasser, Thomas; Harris, Ian; Hauck, Judith; Haverd, Vanessa; Houghton, Richard A.; Hunt, Christopher W.; Hurtt, George; Ilyina, Tatiana; Jain, Atul K.; Kato, Etsushi; Kautz, Markus; Keeling, Ralph F.; Goldewijk, Kees Klein; Koertzinger, Arne; Landschuetzer, Peter; Lefevre, Nathalie; Lenton, Andrew; Lienert, Sebastian; Lima, Ivan; Lombardozzi, Danica; Metzl, Nicolas; Millero, Frank; Monteiro, Pedro M. S.; Munro, David R.; Nabel, Julia E. M. S.; Nakaoka, Shin-ichiro; Nojiri, Yukihiro; Padin, X. Antonio; Peregon, Anna; Pfeil, Benjamin; Pierrot, Denis; Poulter, Benjamin; Rehder, Gregor; Reimer, Janet; Roedenbeck, Christian; Schwinger, Jorg; Seferian, Roland; Skjelvan, Ingunn; Stocker, Benjamin D.; Tian, Hanqin; Tilbrook, Bronte; Tubiello, Francesco N.; van der Laan-Luijkx, Ingrid T.; van der Werf, Guido R.; van Heuven, Steven; Viovy, Nicolas; Vuichard, Nicolas; Walker, Anthony P.; Watson, Andrew J.; Wiltshire, Andrew J.; Zaehle, Soenke; Zhu, Dan

    2018-01-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere - the "global carbon budget" - is important to better understand the global carbon cycle, support the development of climate policies, and project

  10. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Education Safety Education Centers Carbon Monoxide Information Center Carbon Monoxide Information Center En Español The Invisible Killer Carbon monoxide, also known as CO, is called the " ...

  11. Carbon dioxide: emissions and effects

    Energy Technology Data Exchange (ETDEWEB)

    Smith, I M

    1982-01-01

    This review provides a comprehensive guide to work carried out since 1978 in the many disciplines involved in this complex issue. Possible scenarios for carbon dioxide emissions, sources and sinks in the carbon cycle and for climatic changes are examined. The current concensus (by no means unanimous) of specialists on this issue appears to be that a continuation of reduced trends in energy consumption since 1973 is likely to double the atmospheric carbon dioxide concentration to 600 ppmv during the latter part of the next century. However, a higher demand scenario, requiring an upper limit of coal production, would bring forward the doubling to about the middle of the next century. Current climatic models predict that such a concentration of carbon dioxide would cause an average global warming of from 1.0 to 4.5/sup 0/C which might be delayed by the thermal inertia of the oceans. A warming due to estimated increases in carbon dioxide should, if the model results are correct, become apparent at the end of this century. Regional climatic changes are likely to vary considerably and prove disadvantageous to some regions and beneficial to others. Different strategies for dealing with the carbon dioxide issue are considered: no response, alleviation, countermeasures and prevention. It is concluded that uncertainties do not justify either the use of carbon dioxide disposal and other technical fixes at present or a policy of no further growth in fossil fuel consumption. On the other hand, major efforts to conserve energy would give more time to adapt to changes. The alleviation of climatic impacts and other desirable dual-benefit measures are advocated in addition to continuing international, interdisciplinary research on all aspects.

  12. Carbon-14 measurements in aquifers with methane

    International Nuclear Information System (INIS)

    Barker, J.F.; Fritz, P.; Brown, R.M.

    1979-01-01

    A survey of various groundwater systems indicates that methane is a common trace constituent and occasionally a major carbon species in groundwaters. Thermocatalytic methane had delta 13 Csub(CH 4 )>-45 per mille and microbially produced or biogenic methane had delta 13 Csub(CH 4 ) 13 C values for the inorganic carbon. Thermocatalytic methane had no apparent effect on the inorganic carbon. Because methanogenesis seriously affects the carbon isotope geochemistry of groundwaters, the correction of raw 14 C ages of affected groundwaters must consider these effects. Conceptual models are developed which adjust the 14 C activity of the groundwater for the effects of methanogenesis and for the dilution of carbon present during infiltration by simple dissolution of rock carbonate. These preliminary models are applied to groundwaters from the Alliston sand aquifer where methanogenesis has affected most samples. In this system, methanogenic bacteria using organic matter present in the aquifer matrix as substrate have added inorganic carbon to the groundwater which has initiated further carbonate rock dissolution. These processes have diluted the inorganic carbon 14 C activity. The adjusted groundwater ages can be explained in terms of the complex hydrogeology of this aquifer, but also indicate that these conceptual models must be more rigorously tested to evaluate their appropriateness. (author)

  13. Integral Ring Carbon-Carbon Piston

    Science.gov (United States)

    Northam, G. Burton (Inventor)

    1999-01-01

    An improved structure for a reciprocating internal combustion engine or compressor piston fabricate from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variations in thermal expansion differences between the piston and cylinder liner.

  14. Nanostructured Deep Carbon: A Wealth of Possibilities

    Science.gov (United States)

    Navrotsky, A.

    2012-12-01

    The materials science community has been investigating novel forms of carbon including C60 buckyballs, nanodiamond, graphene, carbon "onion" structures with a mixture of sp2 and sp3 bonding , and multicomponent nanostructured Si-O-C-N polymer derived ceramics. Though such materials are generally viewed as metastable, recently measured energetics of several materials suggest that this may not always be the case in multicomponent systems. Finely disseminated carbon phases, including nanodiamonds, have been found in rocks from a variety of deep earth settings. The question then is whether some of the more exotic forms of carbon can also exist in the deep earth or other planetary interiors. This presentation discusses thermodynamic constraints related to surface and interface energies, nanodomain structures, and compositional effects on the possible existence of complex carbon, carbide and oxycarbide nanomaterials at high pressure.

  15. A brief 100 year history of carbon.

    Science.gov (United States)

    Kemp, Terence J

    2017-09-01

    Elemental carbon has been known from time immemorial in its forms of diamond and graphite, while the Industrial Revolution was powered by coal. The molecular structures of diamond and graphite were established following the inception of X-ray crystallography while the complex natures of charcoal and coal have been investigated for 100 years. Recent developments in activated charcoal are described in an article in this issue of Science Progress. However, no-one could have guessed that carbon would have presented such structural surprises as those of C60 fullerene, carbon nanotubes, and graphene. Materials science has benefited from the discovery of carbon fibres, and our understanding of the spectroscopy and bonding in the simplest carbon molecule, C2, has reached new depths.

  16. Carbon nanotube computer.

    Science.gov (United States)

    Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

    2013-09-26

    The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems.

  17. Carbon dioxide sequestration by mineral carbonation

    NARCIS (Netherlands)

    Huijgen, W.J.J.

    2007-01-01

    The increasing atmospheric carbon dioxide (CO2) concentration, mainly caused by fossil fuel combustion, has lead to concerns about global warming. A possible technology that can contribute to the reduction of carbon dioxide emissions is CO2 sequestration by mineral carbonation. The basic concept

  18. Complexed iron removal from groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Munter, R.; Ojaste, H.; Sutt, J. [Tallinn Technical University, Tallinn (Estonia). Dept. of Environmental & Chemical Technology

    2005-07-01

    The paper demonstrates an intensive work carried out and results obtained on the pilot plant of the City of Kogalym Water Treatment Station (Tjumen, Siberia, Russian Federation) to elaborate on a contemporary nonreagent treatment technology for the local iron-rich groundwater. Several filter materials (Birm, Pyrolox, hydroanthracite, Everzit, granulated activated carbon) and chemical oxidants (ozone, chlorine, hydrogen peroxide, oxygen, and potassium permanganate) were tested to solve the problem with complexed iron removal from groundwater. The final elaborated technology consists of raw water intensive aeration in the gas-degas treatment unit followed by sequential filtration through hydroanthracite and the special anthracite Everzit.

  19. Composite carbon foam electrode

    Science.gov (United States)

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  20. Aqueous actinide complexes: A thermochemical assessment

    International Nuclear Information System (INIS)

    Fuger, J.; Khodakovsky, I.L.; Medvedev, V.A.; Navratil, J.D.

    1979-01-01

    The scope and purpose of an assessment of the thermodynamic properties of the aqueous actinide complexes are presented. This work which, at present, is limited to inorganic ligands and three selected organic ligands (formate, acetate and oxalate), is part of an effort established by the International Atomic Energy Agency to assess the thermodynamic properties of the actinides and their compounds. The problems involved in this work are illustrated by discussing the present status of the assessment as related to a few complex species, (hydroxyl-, fluoride-, carbonate complexes). (orig.) [de

  1. Carbon Nanomembranes

    Science.gov (United States)

    Angelova, Polina; Gölzhäuser, Armin

    2017-03-01

    This chapter describes the formation and properties of one nanometer thick carbon nanomembranes (CNMs), made by electron induced cross-linking of aromatic self-assembled monolayers (SAMs). The cross-linked SAMs are robust enough to be released from the surface and placed on solid support or over holes as free-standing membranes. Annealing at 1000K transforms CNMs into graphene accompanied by a change of mechanical stiffness and electrical resistance. The developed fabrication approach is scalable and provides molecular level control over thickness and homogeneity of the produced CNMs. The mechanisms of electron-induced cross-linking process are discussed in details. A variety of polyaromatic thiols: oligophenyls as well as small and extended condensed polycyclic hydrocarbons have been successfully employed, demonstrating that the structural and functional properties of the resulting nanomembranes are strongly determined by the structure of molecular monolayers. The mechanical properties of CNMs (Young's modulus, tensile strength and prestress) are characterized by bulge testing. The interpretation of the bulge test data relates the Young's modulus to the properties of single molecules and to the structure of the pristine SAMs. The gas transport through the CNM is measured onto polydimethylsiloxane (PDMS) - thin film composite membrane. The established relationship of permeance and molecular size determines the molecular sieving mechanism of permeation through this ultrathin sheet.

  2. Carbon 14

    International Nuclear Information System (INIS)

    2002-03-01

    Carbon 14 is one of the most abundant radionuclides of natural and artificial origin in the environment. The aim of this conference day organized by the French society of radioprotection (SFRP) was to take stock of our knowledge about this radionuclide (origins, production, measurement, management, effects on health..): state-of-the-art of 14 C metrology; dating use of 14 C; 14 C management and monitoring of the Hague site environment; Electricite de France (EdF) and 14 C; radiological and sanitary impact of 14 C contamination at the Ganagobie site (Haute-Provence, France); metabolism and biological effects of 14 C; 14 C behaviour in the marine environment near Cogema-La Hague plant; distribution of 14 C activities in waters, mud and sediments of the Loire river estuary; dynamical modeling of transfers in the aquatic and terrestrial environment of 14 C released by nuclear power plants in normal operation: human dose calculation using the Calvados model and application to the Loire river; 14 C distribution in continents; modeling of 14 C transfers in the terrestrial environment from atmospheric sources. (J.S.)

  3. Determination of contents of carbonate and hydrogen carbonate in solutions for alkaline leading of uranium ores

    International Nuclear Information System (INIS)

    Radil, V.

    1988-01-01

    The new analytical method is based on the determination of the molar ratio carbonate - hydrogen carbonate using the measured concentration of hydrogen ions, the determination of the dissociation constant of carbonic acid for different values of ionic strength. The concentration of hydrogen ions was measured with a Metrohm 632 pH meter with the use of a combined glass electrode. The content of total carbonate carbon was determined coulometrically and the uranium content was determined by extraction with tributyl phosphate and by spectrometry of the complex of uranyl ions with Arsenazo III. Model solutions were used for the experiments which contained a high concentration of sulfate ions, thiosulfate ions, uranium and various proportions of carbonate and hydrogen carbonate. The composition of the individual samples of the extraction solutions are tabulated. The calibration was made of the glass combined electrode at different ionic strength, the values determined of dissociation constants of carbonic acid for different ionic strength. The mathematical procedure is described for the calculation of molar concentrations of carbonate and hudrogen carbonate and the results are presented of the analysis of model solutions. (E.S.). 5 tabs., 1 fig., 5 refs

  4. Radiation damage in carbon-carbon composites

    International Nuclear Information System (INIS)

    Burchell, T.D.; Eartherly, W.P.; Nelson, G.E.

    1992-01-01

    Graphite and carbon-carbon composite materials are widely used in plasma facing applications in current Tokamak devices such as TFTR and DIIID in the USA, JET, Tore Supra and TEXTOR in Europe, and JT-60U in Japan. Carbon-carbon composites are attractive choices for Tokamak limiters and diverters because of their low atomic number, high thermal shock resistance, high melting point, and high thermal conductivity. Next generation machines such as the International Thermonuclear Experimental Reactor (ITER) will utilize carbon-carbon composites in their first wall and diverter. ITER will be an ignition machine and thus will produce substantial neutron fluences from the D-T fusion reaction. The resultant high energy neutrons will cause carbon atom displacements in the plasma facing materials which will markedly affect their structure and physical properties. The effect of neutron damage on graphite has been studied for over forty years. Recently the effects of neutron irradiation on the fusion relevant graphite GraphNOL N3M was reviewed. In contrast to graphite, relatively little work has been performed to elucidate the effects of neutron irradiation on carbon-carbon composites. The results of our previous irradiation experiments have been published elsewhere. Here the irradiation induced dimensional changes in 1D, 2D, and 3D carbon-carbon composites are reported for fluences up to 4.7 dpa at an irradiation temperature of 600 degree C

  5. Carbon nanotube composite materials

    Science.gov (United States)

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  6. Mutagenicity of carbon nanomaterials

    DEFF Research Database (Denmark)

    Wallin, Håkan; Jacobsen, Nicklas Raun; White, Paul A

    2011-01-01

    Carbon nanomaterials such carbon nanotubes, graphene and fullerenes are some the most promising nanomaterials. Although carbon nanomaterials have been reported to possess genotoxic potential, it is imperitive to analyse the data on the genotoxicity of carbon nanomaterials in vivo and in vitro...

  7. Carbon doped ZnO: Synthesis, characterization and interpretation

    International Nuclear Information System (INIS)

    Mishra, D.K.; Mohapatra, J.; Sharma, M.K.; Chattarjee, R.; Singh, S.K.; Varma, Shikha; Behera, S.N.; Nayak, Sanjeev K.; Entel, P.

    2013-01-01

    A novel thermal plasma in-flight technique has been adopted to synthesize nanocrystalline ZnO and carbon doped nanocrystalline ZnO matrix. Transmission electron microscopy (TEM) studies on these samples show the average particle sizes to be around 32 nm for ZnO and for carbon doped ZnO. An enhancement of saturation magnetization in nanosized carbon doped ZnO matrix by a factor of 3.8 has been found in comparison to ZnO nanoparticles at room temperature. Raman measurement clearly indicates the presence of Zn–C complexes surrounded by ZnO matrix in carbon doped ZnO. This indicates that the ferromagnetic signature in carbon doped ZnO arises from the creation of defects or the development of oxy-carbon clusters, in the carbon doped ZnO system. Theoretical studies based on density functional theory also support the experimental analyses. - Highlights: ► Synthesis of nanocrystalline ZnO and carbon doped ZnO matrix by inflight thermal plasma reactor. ► Enhancement of ferromagnetism in nanosized carbon doped ZnO in comparison to ZnO nanoparticles. ► Raman measurement indicates the presence of Zn–C complexes surrounded by ZnO matrix. ► Ferromagnetic signature in carbon doped ZnO arises from the development of oxy-carbon clusters. ► DFT supports experimental evidence of ferromagnetism in C doped ZnO nanoparticles.

  8. Mesoporous carbon materials

    Science.gov (United States)

    Dai, Sheng; Fulvio, Pasquale Fernando; Mayes, Richard T.; Wang, Xiqing; Sun, Xiao-Guang; Guo, Bingkun

    2014-09-09

    A conductive mesoporous carbon composite comprising conductive carbon nanoparticles contained within a mesoporous carbon matrix, wherein the conductive mesoporous carbon composite possesses at least a portion of mesopores having a pore size of at least 10 nm and up to 50 nm, and wherein the mesopores are either within the mesoporous carbon matrix, or are spacings delineated by surfaces of said conductive carbon nanoparticles when said conductive carbon nanoparticles are fused with each other, or both. Methods for producing the above-described composite, devices incorporating them (e.g., lithium batteries), and methods of using them, are also described.

  9. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  10. Marine sequestration of carbon in bacterial metabolites.

    Science.gov (United States)

    Lechtenfeld, Oliver J; Hertkorn, Norbert; Shen, Yuan; Witt, Matthias; Benner, Ronald

    2015-03-31

    Linking microbial metabolomics and carbon sequestration in the ocean via refractory organic molecules has been hampered by the chemical complexity of dissolved organic matter (DOM). Here, using bioassay experiments and ultra-high resolution metabolic profiling, we demonstrate that marine bacteria rapidly utilize simple organic molecules and produce exometabolites of remarkable molecular and structural diversity. Bacterial DOM is similar in chemical composition and structural complexity to naturally occurring DOM in sea water. An appreciable fraction of bacterial DOM has molecular and structural properties that are consistent with those of refractory molecules in the ocean, indicating a dominant role for bacteria in shaping the refractory nature of marine DOM. The rapid production of chemically complex and persistent molecules from simple biochemicals demonstrates a positive feedback between primary production and refractory DOM formation. It appears that carbon sequestration in diverse and structurally complex dissolved molecules that persist in the environment is largely driven by bacteria.

  11. Factors effecting carbonate equilibria in natural waters

    International Nuclear Information System (INIS)

    Snellman, M.

    1987-12-01

    This study is related to preliminary stie evaluations to be carried out in 1987-1992 for spent nuclear fuel disposal in Finland. Near surface and shallow groundwaters are characterized by high concentration of calcium and bicarbonate due to dissolution of calcite. The input of carbon dioxide in the upper zone of the bedrock has a strong influence on the pH giving a pH around neutral. In deep groundwaters when the system is no longer open to the input of carbon dioxide the pH rises as the carbonate system is displaced towards the bicarbonate-carbonate site. In still deeper parts of the rock weathering of other minerals such as feldspars affects the chemistry raising the pH and resulting in saturation and precipitation of calcite. The more advanced these reactions become the higher is the pH and the lower is the carbonate content. The equilibrium concentrations of carbonate species are affected both by temperature and ionic strength of the waters, at high ionic strength especially the distribution between bicarbonate and carbonate ions is affected. The total concentration of carbonates in groundwaters is determined through complex interaction between calcite and carbonates in the water. In deep groundwaters which are closed for input of CO 2 the concentration is stated to be regulated by dissolution of calcium carbonate. In deep granitic groundwaters pH is stated to be buffered to 6.5 to 10, where a high pH would correspond to a low total carbonate concentration and often also a low calcium concentration and a low pH would correspond to high carbonae and calcium concentrations

  12. Production of polyol carbonates and their intercalation into Smectite clays

    OpenAIRE

    Shaheen, Uzma

    2017-01-01

    In hyper-saline conditions, clays in geosynthetic clay liners contract and fail to form a hydraulic barrier due to removal of water from the interlayer spaces of smectite, which is the swelling mineral component of bentonites used in geosynthetic clay liners. Five-membered cyclic carbonates such as propylene carbonate have been reported to form stable intercalated complexes with hydrated Na-smectite, which maintain swollen states at 1M). Glycerol carbonate was selected as an alternative c...

  13. STRUCTURE AND CHARACTERISTICS OF PATENTED HIGH-CARBON WIRE

    Directory of Open Access Journals (Sweden)

    A. Ju. Borisenko

    2011-01-01

    Full Text Available The influence of bainite structure on mechanical characteristics of wire of steel 80 after patenting is studied. The quantity and structure state of bainite, providing high complex of mechanical characteristics of high-carbon wire, is determined.

  14. Using Carbon Emissions Data to "Heat Up" Descriptive Statistics

    Science.gov (United States)

    Brooks, Robert

    2012-01-01

    This article illustrates using carbon emissions data in an introductory statistics assignment. The carbon emissions data has desirable characteristics including: choice of measure; skewness; and outliers. These complexities allow research and public policy debate to be introduced. (Contains 4 figures and 2 tables.)

  15. Carbon tetrachloride desorption from activated carbon

    International Nuclear Information System (INIS)

    Jonas, L.A.; Sansone, E.B.

    1981-01-01

    Carbon tetrachloride was desorbed from a granular activated carbon subsequent to its adsorption under various vapor exposure periods. The varied conditions of exposure resulted in a range of partially saturated carbon beds which, when followed by a constant flow rate for desorption, generated different forms of the desorbing concentration versus time curve. A method of analyzing the desorption curves is presented which permits extraction of the various desorbing rates from the different desorption and to relate this to the time required for such regeneration. The Wheeler desorption kinetic equation was used to calculate the pseudo first order desorption rate constant for the carbon. The desorption rate constant was found to increase monotonically with increasing saturation of the bed, permitting the calculation of the maximum desorption rate constant for the carbon at 100% saturation. The Retentivity Index of the carbon, defined as the dimensionless ratio of the adsorption to the desorption rate constant, was found to be 681

  16. Complex analysis and geometry

    CERN Document Server

    Silva, Alessandro

    1993-01-01

    The papers in this wide-ranging collection report on the results of investigations from a number of linked disciplines, including complex algebraic geometry, complex analytic geometry of manifolds and spaces, and complex differential geometry.

  17. Complex Systems: An Introduction

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 9. Complex Systems: An Introduction - Anthropic Principle, Terrestrial Complexity, Complex Materials. V K Wadhawan. General Article Volume 14 Issue 9 September 2009 pp 894-906 ...

  18. Following Carbon Isotopes from Methane to Molecules

    Science.gov (United States)

    Freeman, K. H.

    2017-12-01

    Continuous-flow methods introduced by Hayes (Matthews and Hayes, 1978; Freeman et al., 1990; Hayes et al., 1990) for compound-specific isotope analyses (CSIA) transformed how we study the origins and fates of organic compounds. This analytical revolution launched several decades of research in which researchers connect individual molecular structures to diverse environmental and climate processes affecting their isotopic profiles. Among the first applications, and one of the more dramatic isotopically, was tracing the flow of natural methane into cellular carbon and cellular biochemical constituents. Microbial oxidation of methane can be tracked by strongly 13C-depleted organic carbon in early Earth sedimentary environments, in marine and lake-derived biomarkers in oils, and in modern organisms and their environments. These signatures constrain microbial carbon cycling and inform our understanding of ocean redox. The measurement of molecular isotopes has jumped forward once again, and it is now possible to determine isotope abundances at specific positions within increasingly complex organic structures. In addition, recent analytical developments have lowered sample sensitivity limits of CSIA to picomole levels. These new tools have opened new ways to measure methane carbon in the natural environment and within biochemical pathways. This talk will highlight how molecular isotope methods enable us to follow the fate of methane carbon in complex environments and along diverse metabolic pathways, from trace fluids to specific carbon positions within microbial biomarkers.

  19. Carbon fuel cells with carbon corrosion suppression

    Science.gov (United States)

    Cooper, John F [Oakland, CA

    2012-04-10

    An electrochemical cell apparatus that can operate as either a fuel cell or a battery includes a cathode compartment, an anode compartment operatively connected to the cathode compartment, and a carbon fuel cell section connected to the anode compartment and the cathode compartment. An effusion plate is operatively positioned adjacent the anode compartment or the cathode compartment. The effusion plate allows passage of carbon dioxide. Carbon dioxide exhaust channels are operatively positioned in the electrochemical cell to direct the carbon dioxide from the electrochemical cell.

  20. Complexity, Metastability and Nonextensivity

    Science.gov (United States)

    Beck, C.; Benedek, G.; Rapisarda, A.; Tsallis, C.

    Work and heat fluctuations in systems with deterministic and stochastic forces / E. G. D. Cohen and R. Van Zon -- Is the entropy S[symbol] extensive or nonextensive? / C. Tsallis -- Superstatistics: recent developments and applications / C. Beck -- Two stories outside Boltzmann-Gibbs statistics: Mori's Q-phase transitions and glassy dynamics at the onset of chaos / A. Robledo, F. Baldovin and E. Mayoral -- Time-averages and the heat theorem / A. Carati -- Fundamental formulae and numerical evidences for the central limit theorem in Tsallis statistics / H. Suyari -- Generalizing the Planck distribution / A. M. C. Soma and C. Tsallis -- The physical roots of complexity: renewal or modulation? / P. Grigolini -- Nonequivalent ensembles and metastability / H. Touchette and R. S. Ellis -- Statistical physics for cosmic structures / L. Pietronero and F. Sylos Labini -- Metastability and anomalous behavior in the HMF model: connections to nonextensive thermodynamics and glassy dynamics / A. Pluchino, A. Rapisarda and V. Latora -- Vlasov analysis of relaxation and meta-equilibrium / C. Anteneodo and R. O. Vallejos -- Weak chaos in large conservative systems - infinite-range coupled standard maps / L. G. Moyano, A. P. Majtey and C. Tsallis -- Deterministc aging / E. Barkai -- Edge of chaos of the classical kicked top map: sensitivity to initial conditions / S. M. Duarte Queirós and C. Tsallis -- What entropy at the edge of chaos? / M. Lissia, M. Coraddu and R. Tonelli -- Fractal growth of carbon schwarzites / G. Benedek ... [et al.] -- Clustering and interface propagation in interacting particle dynamics / A. Provata and V. K. Noussiou -- Resonant activation and noise enhanced stability in Josephson junctions / A. L. Pankratov and B. Spagnolo -- Symmetry breaking induced directed motions / C.-H. Chang and T. Y. Tsong -- General theory of Galilean-invariant entropic lattic Boltzmann models / B. M. Boghosian -- Unifying approach to the jamming transition in granular media and

  1. Torsional carbon nanotube artificial muscles.

    Science.gov (United States)

    Foroughi, Javad; Spinks, Geoffrey M; Wallace, Gordon G; Oh, Jiyoung; Kozlov, Mikhail E; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D W; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H

    2011-10-28

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  2. Forest response to carbon dioxide

    International Nuclear Information System (INIS)

    Pitelka, L.

    1992-01-01

    It has been suggested that planting trees could help slow the buildup of carbon dioxide in the atmosphere. Since elevated levels of CO 2 are known to enhance photosynthesis and growth in many plants, it is possible that trees could become progressively more effective in storing carbon as atmospheric CO 2 increases. However, early results from experiments with ponderosa and loblolly pines indicate that the relationship between tree growth and rising CO 2 concentrations may be more complex than scientists once thought. In these experiments, the response to elevated CO 2 has been highly dependent both on species and on mineral nutrient levels in the soil. Further work is necessary to clarify the mechanisms involved. This research will ultimately contribute to an integrated model for predicting forest ecosystem response to elevated CO 2

  3. Escaping carbon lock-in

    International Nuclear Information System (INIS)

    Unruh, G.C.

    2002-01-01

    This article explores the climate policy implications of the arguments made in ''Understanding carbon lock-in'' (Unruh, 2000), which posited that industrial countries have become locked-into fossil fuel-based energy systems through path dependent processes driven by increasing returns to scale. Carbon lock-in arises through technological, organizational, social and institutional co-evolution, ''culminating'' in what was termed as techno-institutional complex (TIC). In order to resolve the climate problem, an escape from the lock-in condition is required. However, due to the self-referential nature of TIC, escape conditions are unlikely to be generated internally and it is argued here that erogenous forces are probably required. (author)

  4. Determining Inorganic and Organic Carbon.

    Science.gov (United States)

    Koistinen, Jaana; Sjöblom, Mervi; Spilling, Kristian

    2017-11-21

    Carbon is the element which makes up the major fraction of lipids and carbohydrates, which could be used for making biofuel. It is therefore important to provide enough carbon and also follow the flow into particulate organic carbon and potential loss to dissolved organic forms of carbon. Here we present methods for determining dissolved inorganic carbon, dissolved organic carbon, and particulate organic carbon.

  5. High frequency conductivity in carbon nanotubes

    Directory of Open Access Journals (Sweden)

    S. S. Abukari

    2012-12-01

    Full Text Available We report on theoretical analysis of high frequency conductivity in carbon nanotubes. Using the kinetic equation with constant relaxation time, an analytical expression for the complex conductivity is obtained. The real part of the complex conductivity is initially negative at zero frequency and become more negative with increasing frequency, until it reaches a resonance minimum at ω ∼ ωB for metallic zigzag CNs and ω < ωB for armchair CNs. This resonance enhancement is indicative for terahertz gain without the formation of current instabilities induced by negative dc conductivity. We noted that due to the high density of states of conduction electrons in metallic zigzag carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency conductivity than the corresponding values for metallic armchair carbon nanotubes. We suggest that this phenomenon can be used to suppress current instabilities that are normally associated with a negative dc differential conductivity.

  6. ELECTROCHEMICAL PROPERTIES OF NANOPOROUS CARBON ELECTRODES

    Directory of Open Access Journals (Sweden)

    P.Nigu

    2002-01-01

    Full Text Available Electrical double layer and electrochemical characteristics at the nanoporous carbon | (C2H54NBF4 + acetonitrile interface have been studied by the cyclic voltammetry and impedance spectroscopy methods. The value of zero charge potential (0.23 V vs. SCE in H2O, the region of ideal polarizability and other characteristics have been established. Analysis of complex plane plots shows that the nanoporous carbon | x M (C2H54NBF4 + acetonitrile interface can be simulated by the equivalent circuit, in which the two parallel conduction parts in the solid and liquid phases are interconnected by the double layer capacitance in parallel with the complex admittance of hindered reaction of the charge transfer process. The values of the characteristic frequency depend on the electrolyte concentration and on the electrode potential, i.e. on the nature of ions adsorbed at the surface of nanoporous carbon electrode.

  7. Acid-base characteristics of powdered-activated-carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Reed, B.E. (West Virginia Univ., Morgantown (United States)); Jensen, J.N.; Matsumoto, M.R. (State Univ. of New York, Buffalo (United States))

    Adsorption of heavy metals onto activated carbon has been described using the surface-complex-formation (SCF) model, a chemical equilibrium model. The SCF model requires a knowledge of the amphoteric nature of activated carbon prior to metal adsorption modeling. In the past, a single-diprotic-acid-site model had been employed to describe the amphoteric nature of activated-carbon surfaces. During this study, the amphoteric nature of two powdered activated carbons were investigated, and a three-monoprotic site surface model was found to be a plausible alternative. The single-diprotic-acid-site and two-monoprotic-site models did not describe the acid-base behavior of the two carbons studied adequately. The two-diprotic site was acceptable for only one of the study carbons. The acid-base behavior of activated carbon surfaces seem to be best modeled as a series of weak monoprotic acids.

  8. Understanding the Organo-Carbonate Associations in Carbonaceous Chondrites with the Use of Micro-Raman Analysis

    Science.gov (United States)

    Chan, Q. H. S.; Zolensky, M. E.

    2015-01-01

    Carbonates can potentially provide sites for organic materials to accrue and develop into complex macromolecules. This study examines the organics associated with carbonates in carbonaceous chondrites using micron-Raman imaging.

  9. Carbon Nanomaterials for Road Construction

    Directory of Open Access Journals (Sweden)

    Zaporotskova Irina Vladimirovna

    2015-05-01

    Full Text Available The requirement of developing and modernizing the roads in Russia and in the Volgograd region in particular, is based on need of expanding the directions of scientific research on road and transport complexes. They have to be aimed at the development of the theory of transport streams, traffic safety increase, and, first of all, at the application of original methods of road development and modernization, introduction of modern technologies and road-building materials.On the basis of the analysis of the plans for transportation sphere development in the Volgograd region assuming the need to apply the new technologies allowing to create qualitative paving, the authors propose the technology of creating a heavy-duty paving with the use of carbon nanomaterial. The knowledge on strengthening the characteristics of carbon nanotubes is a unique material for nanotechnology development which allowed to assume the analysis of general information about asphalt concrete. The analysis showed that carbon nanotubes can be used for improvement of operational characteristics of asphalt concrete, and it is possible to carry out additives of nanotubes in hot as well as in cold bitumen. The article contains the basic principles of creation of the new road material received by means of bitumen reinforcing by carbon nanotubes. The structures received by the offered technique binding on the basis of the bitumens modified by carbon nanomaterial can be used for coverings and bases on highways of all categories in all road and climatic zones of Russia. The technical result consists in increasing the durability and elasticity of the received asphalt covering, and also the increase of water resistance, heat resistance and frost resistance, the expansion of temperature range of its laying in the field of negative temperatures.

  10. Carbon fibers and composites modified by intercalation

    International Nuclear Information System (INIS)

    Macherzynska, B.; Blazewicz, S.

    2002-01-01

    The aim of this paper was to describe ability to intercalation of laboratory prepared carbon composites and their constituents. In work the following materials were tested; pinch-based fibres of P-120 and K-1100 manufacturer's designations, carbon matrix and resulting composites. To prepare a matrix of composites, phenol-formaldehyde resin (Z) and pinch-based precursor (PAK) were used. After initial carbonization, the carbon matrix was heated to 2150 o C i to improve ability to the future intercalation. Three kinds of composites (P/Z, K/Z and K/PAK), with two directional reinforcement (2D), were prepared. All carbon samples were intercalated with copper chloride(II). To study the structure of all materials, before and after intercalation, X-ray diffraction method was used. It enabled to measure microstructure parameters (L c and L a ), interplanar distance (d 002 ) thickness of an intercalation layer (d i ). Before intercalation, graphite fibers are characterized by well developed graphite structure of three-dimensional order, different than carbon turbostratic structures. Graphite fibres show a tendency to intercalation, however this process proceeds harder than in a synthetic graphite, which is testified by diffraction spectra with visible complex stages of intercalation. Comparison of two kinds of graphite fibres show s that their structure significantly affects intercalation process. In the case of composite matrix, a better structure ordering was observed for carbon obtained from PAK than for carbon originating from Z precursor. During production of composites, after the heat treatment (2150 o C), carbon obtained from pyrolysis of Z precursor crystallises on the fibre surface, building a well-developed structure of matrix. The same process occurs during carbonization of pinch-based precursor in presence of graphite fibres. In both cases the composites contain well crystallized graphite phases. The study of carbon composite intercalation shows that the process

  11. Identification of carbonate pedofeatures of different ages in modern chernozems

    Science.gov (United States)

    Kovda, I. V.; Morgun, E. G.; Lebedeva, M. P.; Oleinik, S. A.; Shishkov, V. A.

    2016-07-01

    Carbonate pedofeatures of three chernozemic soils developed from loesslike loams in the foreststeppe zone of Lipetsk oblast under fallow plot (Luvic Chernozem (Clayic, Pachic)) and under forest (Calcic Chernozem (Clayic, Pachic)) and in the steppe zone of Dnepropetrovsk oblast (Calcic Chernozem (Episiltic, Endoclayic, Pachic)) were studied in the field and laboratory with the use of a set of methods, including the radiocarbon method, mass spectrometry, and micro- and submicromorphology. The morphological diversity of carbonate pedofeatures in these soils was represented by carbonate veins, coatings, disperse carbonates (carbonate impregnations), soft masses (beloglazka), and concretions. In the forest-steppe soils, disperse carbonates and soft masses were absent. The radiocarbon age of carbonate pedofeatures in the forest-steppe soils varied within a relatively narrow range of 3-4.3 ka cal BP with a tendency for a younger age of carbonate concretions subjected to destruction (geodes). In the steppe chernozem, this range was larger, and the 14C ages of different forms of carbonate pedofeatures were different. Thus, soft masses (beloglazka) had the age of 5.5-6 ka cal BP; disperse carbonates, 17.5-18.5 ka cal BP; and hard carbonate concretions, 26-27 ka cal BP. Data on δ13C demonstrated that the isotopic composition of carbon in virtually all the "nonlabile" carbonate pedofeatures does not correspond to the isotopic composition of carbon of the modern soil organic matter. It was shown that the studied chernozemic soils are polygenetic formations containing carbonate pedofeatures of different ages: (a) recent (currently growing), (b) relict, and (c) inherited pedofeatures. The latter group represents complex pedofeatures that include ancient fragments integrated in younger pedofeatures, e.g., the Holocene soft carbonate nodules with inclusions of fragments of the ancient microcodium.

  12. Carbon isotopes of dissolved inorganic carbon reflect utilization of different carbon sources by microbial communities in two limestone aquifer assemblages

    Directory of Open Access Journals (Sweden)

    M. E. Nowak

    2017-08-01

    Full Text Available Isotopes of dissolved inorganic carbon (DIC are used to indicate both transit times and biogeochemical evolution of groundwaters. These signals can be complicated in carbonate aquifers, as both abiotic (i.e., carbonate equilibria and biotic factors influence the δ13C and 14C of DIC. We applied a novel graphical method for tracking changes in the δ13C and 14C of DIC in two distinct aquifer complexes identified in the Hainich Critical Zone Exploratory (CZE, a platform to study how water transport links surface and shallow groundwaters in limestone and marlstone rocks in central Germany. For more quantitative estimates of contributions of different biotic and abiotic carbon sources to the DIC pool, we used the NETPATH geochemical modeling program, which accounts for changes in dissolved ions in addition to C isotopes. Although water residence times in the Hainich CZE aquifers based on hydrogeology are relatively short (years or less, DIC isotopes in the shallow, mostly anoxic, aquifer assemblage (HTU were depleted in 14C compared to a deeper, oxic, aquifer complex (HTL. Carbon isotopes and chemical changes in the deeper HTL wells could be explained by interaction of recharge waters equilibrated with post-bomb 14C sources with carbonates. However, oxygen depletion and δ13C and 14C values of DIC below those expected from the processes of carbonate equilibrium alone indicate considerably different biogeochemical evolution of waters in the upper aquifer assemblage (HTU wells. Changes in 14C and 13C in the upper aquifer complexes result from a number of biotic and abiotic processes, including oxidation of 14C-depleted OM derived from recycled microbial carbon and sedimentary organic matter as well as water–rock interactions. The microbial pathways inferred from DIC isotope shifts and changes in water chemistry in the HTU wells were supported by comparison with in situ microbial community structure based on 16S rRNA analyses. Our findings

  13. Multiscale Modeling with Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A

    2006-02-21

    Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

  14. Thorium oxide dissolution kinetics for hydroxide and carbonate complexation

    International Nuclear Information System (INIS)

    Jardin, R.; Curran, V.; Czerwinski, K.R.

    2002-01-01

    The purpose of this project was to determine the kinetics and thermodynamics of thorium oxide dissolution in the environment. Solubility is important because it establishes an upper concentration limit on the concentration of a dissolved radionuclide in solution L1. While understanding the behavior of thorium fuels in the proposed repository at Yucca Mountain is most applicable, a more rigorous study of thorium solubility over a wide pH range was performed so that the data could also be used to model the behavior of thorium fuels in any environmental system. To achieve this, the kinetics and thermodynamics of thorium oxide dissolution under both pure argon and argon with P CO2 of 0. 1 were studied under the full pH range available in each atmosphere. In addition, thorium oxide powder remnants were studied after each experiment to examine structural changes that may affect kinetics

  15. Encapsulating probiotics with an interpolymer complex in supercritical carbon dioxide

    CSIR Research Space (South Africa)

    Moolman, FS

    2006-01-01

    Full Text Available Traditional encapsulation methods in fortified foods and drug delivery applications present difficulties for ‘actives’, such as probiotics, sensitive to exposure to water, solvents, heat or oxygen, where ‘active’ refers to a material, chemical...

  16. Vacancy complexes in carbon and boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG

    2012-10-01

    Full Text Available stream_source_info Mashapa3_2012_ABSTRACT ONLY.pdf.txt stream_content_type text/plain stream_size 1633 Content-Encoding ISO-8859-1 stream_name Mashapa3_2012_ABSTRACT ONLY.pdf.txt Content-Type text/plain; charset=ISO-8859...

  17. Carbon Sequestration in Wetland Soils of the Northern Gulf of Mexico Coastal Region

    Science.gov (United States)

    Coastal wetlands play an important but complex role in the global carbon cycle, contributing to the ecosystem service of greenhouse gas regulation through carbon sequestration. Although coastal wetlands occupy a small percent of the total US land area, their potential for carbon...

  18. Carbon Monoxide Safety

    Science.gov (United States)

    ... with the Media Fire Protection Technology Carbon monoxide safety outreach materials Keep your community informed about the ... KB | Spanish PDF 592 KB Handout: carbon monoxide safety Download this handout and add your organization's logo ...

  19. Trading forest carbon - OSU

    Science.gov (United States)

    Issues associate with trading carbon sequestered in forests are discussed. Scientific uncertainties associated with carbon measurement are discussed with respect to proposed accounting procedures. Major issues include: (1) Establishing baselines. (2) Determining additivity from f...

  20. Geochemistry of sedimentary carbonates

    National Research Council Canada - National Science Library

    Morse, John W; Mackenzie, Fred T

    1990-01-01

    .... The last major section is two chapters on the global cycle of carbon and human intervention, and the role of sedimentary carbonates as indicators of stability and changes in Earth's surface environment...

  1. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Products that contain calcium carbonate are certain: Antacids (Tums, Chooz) Mineral supplements Hand lotions Vitamin and mineral supplements Other products may also contain ...

  2. Carbon Based Nanotechnology: Review

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash (Technical Monitor)

    1999-01-01

    This presentation reviews publicly available information related to carbon based nanotechnology. Topics covered include nanomechanics, carbon based electronics, nanodevice/materials applications, nanotube motors, nano-lithography and H2O storage in nanotubes.

  3. Sodium carbonate poisoning

    Science.gov (United States)

    Sodium carbonate (known as washing soda or soda ash) is a chemical found in many household and industrial products. This article focuses on poisoning due to sodium carbonate. This article is for information only. Do NOT ...

  4. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  5. Graphitization in Carbon MEMS and Carbon NEMS

    Science.gov (United States)

    Sharma, Swati

    Carbon MEMS (CMEMS) and Carbon NEMS (CNEMS) are an emerging class of miniaturized devices. Due to the numerous advantages such as scalable manufacturing processes, inexpensive and readily available precursor polymer materials, tunable surface properties and biocompatibility, carbon has become a preferred material for a wide variety of future sensing applications. Single suspended carbon nanowires (CNWs) integrated on CMEMS structures fabricated by electrospinning of SU8 photoresist on photolithographially patterned SU8 followed by pyrolysis are utilized for understanding the graphitization process in micro and nano carbon materials. These monolithic CNW-CMEMS structures enable the fabrication of very high aspect ratio CNWs of predefined length. The CNWs thus fabricated display core---shell structures having a graphitic shell with a glassy carbon core. The electrical conductivity of these CNWs is increased by about 100% compared to glassy carbon as a result of enhanced graphitization. We explore various tunable fabrication and pyrolysis parameters to improve graphitization in the resulting CNWs. We also suggest gas-sensing application of the thus fabricated single suspended CNW-CMEMS devices by using the CNW as a nano-hotplate for local chemical vapor deposition. In this thesis we also report on results from an optimization study of SU8 photoresist derived carbon electrodes. These electrodes were applied to the simultaneous detection of traces of Cd(II) and Pb(II) through anodic stripping voltammetry and detection limits as low as 0.7 and 0.8 microgL-1 were achieved. To further improve upon the electrochemical behavior of the carbon electrodes we elucidate a modified pyrolysis technique featuring an ultra-fast temperature ramp for obtaining bubbled porous carbon from lithographically patterned SU8. We conclude this dissertation by suggesting the possible future works on enhancing graphitization as well as on electrochemical applications

  6. Uranium nucleophilic carbene complexes

    International Nuclear Information System (INIS)

    Tourneux, Jean-Christophe

    2012-01-01

    The only stable f-metal carbene complexes (excluding NHC) metals f present R 2 C 2- groups having one or two phosphorus atoms in the central carbon in alpha position. The objective of this work was to develop the chemistry of carbenes for uranium (metal 5f) with the di-anion C{Ph 2 P(=S)} 2 2- (SCS 2- ) to extend the organometallic chemistry of this element in its various oxidation states (+3-+6), and to reveal the influence of the 5f orbitals on the nature and reactivity of the double bond C=U. We first isolated the reactants M(SCHS) (M = Li and K) and demonstrated the role of the cation M + on the evolution of the di-anion M 2 SCS (M = Li, K, Tl) which is transformed into LiSCHS in THF or into product of intramolecular cyclization K 2 [C(PhPS) 2 (C 6 H 4 )]. We have developed the necessary conditions mono-, bis- and tris-carbene directly from the di-anion SCS 2- and UCl 4 , as the precursor used in uranium chemistry. The protonolysis reactions of amides compounds (U-NEt 2 ) by the neutral ligand SCH 2 S were also studied. The compounds [Li(THF)] 2 [U(SCS)Cl 3 ] and [U(SCS)Cl 2 (THF) 2 ] were then used to prepare a variety of cyclopentadienyl and mono-cyclo-octa-tetra-enyliques uranium(IV) carbene compounds of the DFT analysis of compounds [M(SCS)Cl 2 (py) 2 ] and [M(Cp) 2 (SCS)] (M = U, Zr) reveals the strong polarization of the M=C double bond, provides information on the nature of the σ and π interactions in this binding, and shows the important role of f orbitals. The influence of ancillary ligands on the M=C bond is revealed by examining the effects of replacing Cl - ligands and pyridine by C 5 H 5 - groups. Mulliken and NBO analyzes show that U=C bond, unlike the Zr=C bond, is not affected by the change in environment of the metal center. While the oxidation tests of carbene complexes of U(IV) were disappointing, the first carbene complex of uranium (VI), [UO 2 (SCS)(THF) 2 ], was isolated with the uranyl ion UO 2 2+ . The reactions of compounds UO 2 X 2

  7. Carbon offsetting: sustaining consumption?

    OpenAIRE

    Heather Lovell; Harriet Bulkeley; Diana Liverman

    2009-01-01

    In this paper we examine how theories of sustainable and ethical consumption help us to understand a new, rapidly expanding type of consumer product designed to mitigate climate change: carbon offsets. The voluntary carbon offset market grew by 200% between 2005 and 2006, and there are now over 150 retailers of voluntary carbon offsets worldwide. Our analysis concentrates on the production and consumption of carbon offsets, drawing on ideas from governmentality and political ecology about how...

  8. Yeast Carbon Catabolite Repression†

    Science.gov (United States)

    Gancedo, Juana M.

    1998-01-01

    Glucose and related sugars repress the transcription of genes encoding enzymes required for the utilization of alternative carbon sources; some of these genes are also repressed by other sugars such as galactose, and the process is known as catabolite repression. The different sugars produce signals which modify the conformation of certain proteins that, in turn, directly or through a regulatory cascade affect the expression of the genes subject to catabolite repression. These genes are not all controlled by a single set of regulatory proteins, but there are different circuits of repression for different groups of genes. However, the protein kinase Snf1/Cat1 is shared by the various circuits and is therefore a central element in the regulatory process. Snf1 is not operative in the presence of glucose, and preliminary evidence suggests that Snf1 is in a dephosphorylated state under these conditions. However, the enzymes that phosphorylate and dephosphorylate Snf1 have not been identified, and it is not known how the presence of glucose may affect their activity. What has been established is that Snf1 remains active in mutants lacking either the proteins Grr1/Cat80 or Hxk2 or the Glc7 complex, which functions as a protein phosphatase. One of the main roles of Snf1 is to relieve repression by the Mig1 complex, but it is also required for the operation of transcription factors such as Adr1 and possibly other factors that are still unidentified. Although our knowledge of catabolite repression is still very incomplete, it is possible in certain cases to propose a partial model of the way in which the different elements involved in catabolite repression may be integrated. PMID:9618445

  9. Preliminary studies of cobalt complexation in groundwater

    International Nuclear Information System (INIS)

    Warwick, P.; Shaw, P.; Williams, G.M.; Hooker, P.J.

    1988-01-01

    A relatively non-invasive method has been used to separate complexed from free cobalt-60 in groundwater, using the weak cationic adsorption properties of Sephadex gels, and a mobile phase of natural groundwater. Results show the kinetics of Co complex formation in groundwater to be slow, and that the equilibrium position is affected by temperature, cobalt concentration and the ionic/organic strength of the groundwater. The addition of DEAE cellulose to the groundwater to remove humic material, also removed the majority of organic species with absorb UV at 254 nm, but 45% of the original total organic carbon remained, and the amount of complexed cobalt left in solution was only reduced to 76% of its former concentration. This suggests that the complexed Co species separated by the method described in this paper are a mixture of inorganic and organic compounds, and studies are therefore continuing to establish their exact nature. (orig.)

  10. Carbon activity meter

    International Nuclear Information System (INIS)

    Roy, P.; Krankota, J.L.

    1975-01-01

    A carbon activity meter utilizing an electrochemical carbon cell with gaseous reference electrodes having particular application for measuring carbon activity in liquid sodium for the LMFBR project is described. The electrolyte container is electroplated with a thin gold film on the inside surface thereof, and a reference electrode consisting of CO/CO 2 gas is used. (U.S.)

  11. Protolytic carbon film technology

    Energy Technology Data Exchange (ETDEWEB)

    Renschler, C.L.; White, C.A.

    1996-04-01

    This paper presents a technique for the deposition of polyacrylonitrile (PAN) on virtually any surface allowing carbon film formation with only the caveat that the substrate must withstand carbonization temperatures of at least 600 degrees centigrade. The influence of processing conditions upon the structure and properties of the carbonized film is discussed. Electrical conductivity, microstructure, and morphology control are also described.

  12. Carbon Goes To…

    Science.gov (United States)

    Savasci, Funda

    2014-01-01

    The purposes of this activity are to help middle school students understand the carbon cycle and realize how human activities affect the carbon cycle. This activity consists of two parts. The first part of the activity focuses on the carbon cycle, especially before the Industrial Revolution, while the second part of the activity focuses on how…

  13. Global Carbon Budget 2016

    NARCIS (Netherlands)

    Le Quéré, Corinne; Andrew, Robbie M.; Canadell, Josep G.; Sitch, Stephen; Ivar Korsbakken, Jan; Peters, Glen P.; Manning, Andrew C.; Boden, Thomas A.; Tans, Pieter P.; Houghton, Richard A.; Keeling, Ralph F.; Alin, Simone; Andrews, Oliver D.; Anthoni, Peter; Barbero, Leticia; Bopp, Laurent; Chevallier, Frédéric; Chini, Louise P.; Ciais, Philippe; Currie, Kim; Delire, Christine; Doney, Scott C.; Friedlingstein, Pierre; Gkritzalis, Thanos; Harris, Ian A; Hauck, Judith; Haverd, Vanessa; Hoppema, Mario; Klein Goldewijk, Kees; Jain, Atul K.; Kato, Etsushi; Körtzinger, Arne; Landschützer, Peter; Lefèvre, Nathalie; Lenton, Andrew; Lienert, Sebastian; Lombardozzi, Danica; Melton, Joe R.; Metzl, Nicolas; Millero, Frank; Monteiro, Pedro M S; Munro, David R.; Nabel, Julia E M S; Nakaoka, Shin Ichiro; O'Brien, Kevin; Olsen, Are; Omar, Abdirahman M.; Ono, Tsuneo; Pierrot, Denis; Poulter, Benjamin; Rödenbeck, Christian; Salisbury, Joe; Schuster, Ute; Schwinger, Jörg; Séférian, Roland; Skjelvan, Ingunn; Stocker, Benjamin D.; Sutton, Adrienne J.; Takahashi, Taro; Tian, Hanqin; Tilbrook, Bronte; Van Der Laan-Luijkx, Ingrid T.; Van Der Werf, Guido R.; Viovy, Nicolas; Walker, Anthony P.; Wiltshire, Andrew J.; Zaehle, Sönke

    2016-01-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere-the "global carbon budget"-is important to better understand the global carbon cycle, support the development of climate policies, and project future

  14. Global Carbon Budget 2016

    NARCIS (Netherlands)

    Quéré, Le Corinne; Andrew, Robbie M.; Canadell, Josep G.; Sitch, Stephen; Korsbakken, Jan Ivar; Peters, Glen P.; Manning, Andrew C.; Boden, Thomas A.; Tans, Pieter P.; Houghton, Richard A.; Keeling, Ralph F.; Alin, Simone; Andrews, Oliver D.; Anthoni, Peter; Barbero, Leticia; Bopp, Laurent; Chevallier, Frédéric; Chini, Louise P.; Ciais, Philippe; Currie, Kim; Delire, Christine; Doney, Scott C.; Friedlingstein, Pierre; Gkritzalis, Thanos; Harris, Ian; Hauck, Judith; Haverd, Vanessa; Hoppema, Mario; Klein Goldewijk, Kees; Jain, Atul K.; Kato, Etsushi; Körtzinger, Arne; Landschützer, Peter; Lefèvre, Nathalie; Lenton, Andrew; Lienert, Sebastian; Lombardozzi, Danica; Melton, Joe R.; Metzl, Nicolas; Millero, Frank; Monteiro, Pedro M.S.; Munro, David R.; Nabel, Julia E.M.S.; Nakaoka, S.; O'Brien, Kevin; Olsen, Are; Omar, Abdirahman M.; Ono, Tsuneo; Pierrot, Denis; Poulter, Benjamin; Rödenbeck, Christian; Salisbury, Joe; Schuster, Ute; Schwinger, Jörg; Séférian, Roland; Skjelvan, Ingunn; Stocker, Benjamin D.; Sutton, Adrienne J.; Takahashi, Taro; Tian, Hanqin; Tilbrook, Bronte; Laan-Luijkx, van der Ingrid T.; Werf, van der Guido R.; Viovy, Nicolas; Walker, Anthony P.; Wiltshire, Andrew J.; Zaehle, Sönke

    2016-01-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project

  15. New Insight into Carbon Nanotube Electronic Structure Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Jiang, Deen [ORNL

    2009-01-01

    The fundamental role of aryl diazonium salts for post synthesis selectivity of carbon nanotubes is investigated using extensive electronic structure calculations. The resulting understanding for diazonium salt based selective separation of conducting and semiconducting carbon nanotubes shows how the primary contributions come from the interplay between the intrinsic electronic structure of the carbon nanotubes and that of the anion of the salt. We demonstrate how the electronic transport properties change upon the formation of charge transfer complexes and upon their conversion into covalently attached functional groups. Our results are found to correlate well with experiments and provide for the first time an atomistic description for diazonium salt based chemical separation of carbon nanotubes

  16. Distribution of cadmium between calcium carbonate and solution, 2

    International Nuclear Information System (INIS)

    Kitano, Yasushi; Kanamori, Nobuko; Fujiyoshi, Ryoko

    1978-01-01

    The distribution coefficient of cadmium between calcite and solution has been measured in the calcium bicarbonate solution containing cadmium and chloride ions, which forms complexes with cadmium ions. It has been confirmed experimentally that cadmium carbonate is present as a solid solution between calcitic calcium carbonate and cadmium carbonate in the carbonate precipitate formed in the solution system. However, the constant value of the thermodynamic distribution coefficient of cadmium between calcite and solution has not been obtained experimentally in the calcium bicarbonate solution containing cadmium and chloride ions. It may have been caused by the very specific behavior of cadmium ions, but the exact reason remains unsolved and must be studied. (Kobatake, H.)

  17. Carbon/Carbon Pistons for Internal Combustion Engines

    Science.gov (United States)

    Taylor, A. H.

    1986-01-01

    Carbon/carbon piston performs same function as aluminum pistons in reciprocating internal combustion engines while reducing weight and increasing mechanical and thermal efficiencies of engine. Carbon/carbon piston concept features low piston-to-cylinder wall clearance - so low piston rings and skirts unnecessary. Advantages possible by negligible coefficient of thermal expansion of carbon/carbon.

  18. Catalytic hydrogenation of carbon monoxide

    International Nuclear Information System (INIS)

    Wayland, B.B.

    1993-12-01

    Focus of this project is on developing new approaches for hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. The strategies to accomplish CO reduction are based on favorable thermodynamics manifested by rhodium macrocycles for producing a series of intermediates implicated in the catalytic hydrogenation of CO. Metalloformyl complexes from reactions of H 2 and CO, and CO reductive coupling to form metallo α-diketone species provide alternate routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics are promising candidates for future development

  19. Carbon dioxide sequestration by aqueous mineral carbonation of magnesium silicate minerals

    Energy Technology Data Exchange (ETDEWEB)

    Gerdemann, Stephen J.; Dahlin, David C.; O' Connor, William K.; Penner, Larry R.

    2003-01-01

    The dramatic increase in atmospheric carbon dioxide since the Industrial Revolution has caused concerns about global warming. Fossil-fuel-fired power plants contribute approximately one third of the total human-caused emissions of carbon dioxide. Increased efficiency of these power plants will have a large impact on carbon dioxide emissions, but additional measures will be needed to slow or stop the projected increase in the concentration of atmospheric carbon dioxide. By accelerating the naturally occurring carbonation of magnesium silicate minerals it is possible to sequester carbon dioxide in the geologically stable mineral magnesite (MgCO3). The carbonation of two classes of magnesium silicate minerals, olivine (Mg2SiO4) and serpentine (Mg3Si2O5(OH)4), was investigated in an aqueous process. The slow natural geologic process that converts both of these minerals to magnesite can be accelerated by increasing the surface area, increasing the activity of carbon dioxide in the solution, introducing imperfections into the crystal lattice by high-energy attrition grinding, and in the case of serpentine, by thermally activating the mineral by removing the chemically bound water. The effect of temperature is complex because it affects both the solubility of carbon dioxide and the rate of mineral dissolution in opposing fashions. Thus an optimum temperature for carbonation of olivine is approximately 185 degrees C and 155 degrees C for serpentine. This paper will elucidate the interaction of these variables and use kinetic studies to propose a process for the sequestration of the carbon dioxide.

  20. Observation of carbon growth and interface structures in methanol solution

    Science.gov (United States)

    Okuno, Kimio

    2015-11-01

    In the deposition of carbon on the surface of a tungsten tip in methanol solution by electrolysis, the growth structure of the carbon films, the interface state, and the dissolution of carbon atoms into the tungsten matrix of the substrate have been investigated with the atomic events by field ion microscopy (FIM). The carbon films preferentially condense on the W{111} plane. The interfacial reaction at the carbon atom-tungsten substrate interface is vigorous and the carbon atoms also readily dissolve into the substrate matrix to form a tungsten-carbon complex. The reaction depth of the deposited carbon depends on the magnitude of electrolytic current and the treatment duration in the methanol solution. In this work, the resolution depth of carbon was found to be approximately 270 atomic layers below the top layer of the tungsten substrate by a field evaporation technique. In the case of a low electrolytic current, the tungsten substrate surface is entirely covered with carbon atoms having a pseudomorphic structure. The field-electron emission characteristics were also evaluated for various coverages of the carbon film formed on the substrate.