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Sample records for bifunctional coupling agents

  1. Investigation of new bifunctional agents. D-Penicillamine

    International Nuclear Information System (INIS)

    Somatostatin inhibits the release of growth hormone (somatotropin) from the Anterior Pituitary. The main use of derivatives of somatostatin is to diagnose growth hormone problems and to use against some forms of cancer which involve growth hormone. Also somatostatin suppresses gastric acid secretion, gallbladder contractions, and pancreatic enzyme secretion. The aim of the current study is to investigate new bifunctional agents for labeling with 99mTc. Therefore D-Penicillamine was used as a bifunctional agent and compared to DTPA in the labeling with 99mTc. Quality controls were established using thin layer radio chromatography (TLRC) and electrophoresis techniques. In addition, high performance liquid radio chromatography (HPLRC) was also performed for elimination of possible uncertainties. The radiolabeled complexes maintained their stabilities throughout the study. The results obtained showed that 99mTc-D-Penicillamine-somatostatin is a promising potential radiopharmaceutical and an alternative of 99mTc-DTPA-somatostatin for in vivo and in vitro applications. (author)

  2. [Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

    International Nuclear Information System (INIS)

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III)

  3. [Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-31

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

  4. (Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

  5. Bifunctional chelating agent for the design and development of site specific radiopharmaceuticals and biomolecule conjugation strategy

    Science.gov (United States)

    Katti, Kattesh V.; Prabhu, Kandikere R.; Gali, Hariprasad; Pillarsetty, Nagavara Kishore; Volkert, Wynn A.

    2003-10-21

    There is provided a method of labeling a biomolecule with a transition metal or radiometal in a site specific manner to produce a diagnostic or therapeutic pharmaceutical compound by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radio metal or a transition metal, and covalently linking the resulting metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. Also provided is a method of synthesizing the --PR.sub.2 containing biomolecules by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radiometal or a transition metal, and covalently linking the resulting radio metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. There is provided a therapeutic or diagnostic agent comprising a --PR.sub.2 containing biomolecule.

  6. Morphology-controlled growth of magnetic iron oxide components on gold nanoparticles as bi-functional agents

    OpenAIRE

    Li, L.; Leung, CW; Ruotolo, A.; Jiang, C; Pong, PWT

    2015-01-01

    Summary form only given. Hybrid nanostructure can inherit the physiochemical properties of its individual components to realize its multi-functionality. The coupling of plasmonic effect of gold nanoparticles with magnetic properties of iron oxide nanoparticles has shown great promise as bi-functional agents allowing simultaneous magnetic resonance imaging (MRI)/computed tomography (CT) imaging and magnetic/photonic thermal therapy. However, since gold and iron oxide are two dissimilar materia...

  7. Bifunctional chelating agents for targeted α-particle radiotherapy

    International Nuclear Information System (INIS)

    An α-emitting radionuclide is proposed as a better choice for application in radiotherapy of either leukemias or lymphomas due to very high cytotoxicity, short emission path length, and immediate energy deposition minimizing collateral cytotoxicity. Metallic α-emitters that have been studied are 212Bi and 213Bi. Bifunctional derivatives of diethylenetriamine pentaacetic acid (DTPA) were found to form Bi(III) complexes that were labile in vivo. Pre-clinical experiments confirmed both the stability of the CHX-DTPA ligands for the Bi(III) isotopes and the therapeutic applicability of these α-emitting isotopes

  8. The use of bifunctional polyethyleneglycol derivatives for coupling of proteins to and cross-linking of collagen matrices.

    Science.gov (United States)

    Chen, J-S; Noah, E M; Pallua, N; Steffens, G C M

    2002-11-01

    The realization of three-dimensional (3D) degradable matrices which slowly release bio-active components represents a major challenge in the field of tissue engineering. In this paper we report on the usage of commercially available bifunctional agents for both the covalent coupling of proteins to and the cross-linking of collagen matrices. Proteins - horse radish peroxidase (HRP) was used as a model protein - were cross-linked with either a homobifunctional (disuccinimidyldisuccinatepolyethylene-glycol) or a heterobifunctional (N-hydroxysuccinimidylvinylsulfonepolyethyleneglycol) agent. In the case of the heterobifunctional cross-linking agent the collagen matrices were previously modified with succinimidylacetylthioacetate in order to introduce sulfhydryl groups. As compared with control experiments a 10-fold and 50-fold increase of immobilized proteins were achieved with the homobifunctional and heterobifunctional cross-linker resp. The HRP-PEG conjugates demonstrated a better long-term stability as compared to the non-treated HRP. The effects of the cross-linking agents and the thiolation reagent succinimidylacetylthio acetate on the in vitro degradation of the collagen matrices by collagenase were also investigated. In particular the reaction with succinimidylacetylthio acetate appears to offer interesting opportunities both for coupling active proteins and modulating the degradation times of collagen matrices. PMID:15348172

  9. Novel 3-nitrotriazole-based amides and carbinols as bifunctional antichagasic agents.

    Science.gov (United States)

    Papadopoulou, Maria V; Bloomer, William D; Lepesheva, Galina I; Rosenzweig, Howard S; Kaiser, Marcel; Aguilera-Venegas, Benjamín; Wilkinson, Shane R; Chatelain, Eric; Ioset, Jean-Robert

    2015-02-12

    3-Nitro-1H-1,2,4-triazole-based amides with a linear, rigid core and 3-nitrotriazole-based fluconazole analogues were synthesized as dual functioning antitrypanosomal agents. Such compounds are excellent substrates for type I nitroreductase (NTR) located in the mitochondrion of trypanosomatids and, at the same time, act as inhibitors of the sterol 14α-demethylase (T. cruzi CYP51) enzyme. Because combination treatments against parasites are often superior to monotherapy, we believe that this emerging class of bifunctional compounds may introduce a new generation of antitrypanosomal drugs. In the present work, the synthesis and in vitro and in vivo evaluation of such compounds is discussed. PMID:25580906

  10. Defective DNA cross-link removal in Chinese hamster cell mutants hypersensitive to bifunctional alkylating agents

    International Nuclear Information System (INIS)

    DNA repair-deficient mutants from five genetic complementation groups isolated previously from Chinese hamster cells were assayed for survival after exposure to the bifunctional alkylating agents mitomycin C or diepoxybutane. Groups 1, 3, and 5 exhibited 1.6- to 3-fold hypersensitivity compared to the wild-type cells, whereas Groups 2 and 4 exhibited extraordinary hypersensitivity. Mutants from Groups 1 and 2 were exposed to 22 other bifunctional alkylating agents in a rapid assay that compared cytotoxicity of the mutants to the wild-type parental strain, AA8. With all but two of the compounds, the Group 2 mutant (UV4) was 15- to 60-fold more sensitive than AA8 or the Group 1 mutant (UV5). UV4 showed only 6-fold hypersensitivity to quinacrine mustard. Alkaline elution measurements showed that this compound produced few DNA interstrand cross-links but numerous strand breaks. Therefore, the extreme hypersensitivity of mutants from Groups 2 and 4 appeared specific for compounds the main cytotoxic lesions of which were DNA cross-links. Mutant UV5 was only 1- to 4-fold hypersensitive to all the compounds. Although the initial number of cross-links was similar for the three cell lines, the efficiency of removal of cross-links was lowest in UV4 and intermediate in UV5. These results suggest that the different levels of sensitivity are specifically related to different efficiencies of DNA cross-link removal. The phenotype of hypersensitivity to both UV radiation and cross-link damage exhibited by the mutants in Groups 2 and 4 appears to differ from those of the known human DNA repair syndromes

  11. Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Wang, Wenpin; Xu, Min; Wang, Shubo; Xie, Xiaofeng; Lv, Yafei; Ramani, Vijay K

    2014-06-01

    A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV). PMID:24884171

  12. Efficient refolding of the bifunctional therapeutic fusion protein VAS-TRAIL by a triple agent solution.

    Science.gov (United States)

    Fan, Jiying; Wang, Zhanqing; Huang, Liying; Shen, Yaling

    2016-09-01

    VAS-TRAIL is a bifunctional fusion protein that combines anti-angiogenic activity with tumor-selective apoptotic activity for enhanced anti-tumor efficacy. VAS-TRAIL is expressed as inclusion body in Escherichia coli, but protein refolding is difficult to achieve and results in low yields of bioactive protein. In this study, we describe an efficient method for VAS-TRAIL refolding. The solubilization of aggregated VAS-TRAIL was achieved by a triple agent solution, which consists of an alkaline solution (pH 11.5) containing 0.4M l-arginine and 2M urea. The solubilized protein showed high purity and preserved secondary structure according to fluorescence properties. VAS-TRAIL refolding was performed through stepwise dialysis and resulted in more than 50% recovery of the soluble protein. The function of l-arginine was additive with alkaline pH, as shown by the significant improvement in refolding yield (≈30%) by l-arginine-containing solubilization solutions compared with alkaline solubilization solutions without l-arginine. The refolded VAS-TRAIL also showed β-sheet structures and the propensity for oligomerization. Bioassays showed that the refolded fusion protein exhibited the expected activities, including its apoptotic activities toward tumor and endothelial cells, which proposed its promising therapeutic potential. PMID:26358405

  13. Cell tracking with gadophrin-2: a bifunctional contrast agent for MR imaging, optical imaging, and fluorescence microscopy

    International Nuclear Information System (INIS)

    The purpose of this study was to assess the feasibility of use of gadophrin-2 to trace intravenously injected human hematopoietic cells in athymic mice, employing magnetic resonance (MR) imaging, optical imaging (OI), and fluorescence microscopy. Mononuclear peripheral blood cells from GCSF-primed patients were labeled with gadophrin-2 (Schering AG, Berlin, Germany), a paramagnetic and fluorescent metalloporphyrin, using established transfection techniques with cationic liposomes. The labeled cells were evaluated in vitro with electron microscopy and inductively coupled plasma atomic emission spectrometry. Then, 1 x 106-3 x 108 labeled cells were injected into 14 nude Balb/c mice and the in vivo cell distribution was evaluated with MR imaging and OI before and 4, 24, and 48 h after intravenous injection (p.i.). Five additional mice served as controls: three mice were untreated controls and two mice were investigated after injection of unlabeled cells. The contrast agent effect was determined quantitatively for MR imaging by calculating signal-to-noise-ratio (SNR) data. After completion of in vivo imaging studies, fluorescence microscopy of excised organs was performed. Intracellular cytoplasmatic uptake of gadophrin-2 was confirmed by electron microscopy. Spectrometry determined an uptake of 31.56 nmol Gd per 106 cells. After intravenous injection, the distribution of gadophrin-2 labeled cells in nude mice could be visualized by MR, OI, and fluorescence microscopy. At 4 h p.i., the transplanted cells mainly distributed to lung, liver, and spleen, and 24 h p.i. they also distributed to the bone marrow. Fluorescence microscopy confirmed the distribution of gadophrin-2 labeled cells to these target organs. Gadophrin-2 is suited as a bifunctional contrast agent for MR imaging, OI, and fluorescence microscopy and may be used to combine the advantages of each individual imaging modality for in vivo tracking of intravenously injected hematopoietic cells. (orig.)

  14. Cell tracking with gadophrin-2: a bifunctional contrast agent for MR imaging, optical imaging, and fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Daldrup-Link, Heike E. [Department of Radiology, UCSF Medical Center, University of California in San Francisco, 513 Parnassus Ave, CA 94143, San Francisco (United States); Rudelius, Martina; Piontek, Guido; Schlegel, Juergen [Institute of Pathology, Technical University, Munich (Germany); Metz, Stephan; Settles, Marcus; Rummeny, Ernst J. [Department of Radiology, Technical University, Munich (Germany); Pichler, Bernd [Department of Biomedical Engineering, University of California Davis, Davis (United States); Heinzmann, Ulrich [National Research Center for Environment and Health, Technical University, Munich (Germany); Oostendorp, Robert A.J. [3. Clinic of Internal Medicine, Laboratory of Stem Cell Physiology, Technical University, Munich (Germany)

    2004-09-01

    The purpose of this study was to assess the feasibility of use of gadophrin-2 to trace intravenously injected human hematopoietic cells in athymic mice, employing magnetic resonance (MR) imaging, optical imaging (OI), and fluorescence microscopy. Mononuclear peripheral blood cells from GCSF-primed patients were labeled with gadophrin-2 (Schering AG, Berlin, Germany), a paramagnetic and fluorescent metalloporphyrin, using established transfection techniques with cationic liposomes. The labeled cells were evaluated in vitro with electron microscopy and inductively coupled plasma atomic emission spectrometry. Then, 1 x 10{sup 6}-3 x 10{sup 8} labeled cells were injected into 14 nude Balb/c mice and the in vivo cell distribution was evaluated with MR imaging and OI before and 4, 24, and 48 h after intravenous injection (p.i.). Five additional mice served as controls: three mice were untreated controls and two mice were investigated after injection of unlabeled cells. The contrast agent effect was determined quantitatively for MR imaging by calculating signal-to-noise-ratio (SNR) data. After completion of in vivo imaging studies, fluorescence microscopy of excised organs was performed. Intracellular cytoplasmatic uptake of gadophrin-2 was confirmed by electron microscopy. Spectrometry determined an uptake of 31.56 nmol Gd per 10{sup 6} cells. After intravenous injection, the distribution of gadophrin-2 labeled cells in nude mice could be visualized by MR, OI, and fluorescence microscopy. At 4 h p.i., the transplanted cells mainly distributed to lung, liver, and spleen, and 24 h p.i. they also distributed to the bone marrow. Fluorescence microscopy confirmed the distribution of gadophrin-2 labeled cells to these target organs. Gadophrin-2 is suited as a bifunctional contrast agent for MR imaging, OI, and fluorescence microscopy and may be used to combine the advantages of each individual imaging modality for in vivo tracking of intravenously injected hematopoietic cells

  15. Hexadentate bispidine derivatives as versatile bifunctional chelate agents for copper(II) radioisotopes.

    Science.gov (United States)

    Juran, Stefanie; Walther, Martin; Stephan, Holger; Bergmann, Ralf; Steinbach, Jörg; Kraus, Werner; Emmerling, Franziska; Comba, Peter

    2009-02-01

    The preparation and use of bispidine derivatives (3,7-diazabicyclo[3.3.1]nonane) as chelate ligands for radioactive copper isotopes for diagnosis (64Cu) or therapy (67Cu) are reported. Starting from the hexadentate bispidine-based bis(amine)tetrakis(pyridine) ligand 1 with a keto and two ester substituents, the corresponding mono-ol 2 and two dicarboxylic acid derivatives 3 and 5 have been synthesized. A range of techniques, including single-crystal X-ray structure analysis, UV/vis spectroscopy, cyclic voltammetry, thin-layer- (TLC), and high-performance liquid chromatography (HPLC), have been used to characterize the structure and stability of the copper(II)-bispidine complexes. A rapid formation (within 1 min) of stable copper(II)-bispidine complexes under mild conditions (ambient temperature, aqueous solution) has been observed. Challenge experiments of these complexes in the presence of a high excess of competing ligands, such as glutathione, cyclam, or superoxide dismutase (SOD), as well as in rat plasma, gave no evidence of demetalation or transchelation. The bifunctional bispidine derivative 5 can be readily functionalized with biologically active molecules at the pendant carboxylate groups. The coupling of a bombesin analogue betahomo-Glu-betaAla-betaAla-[Cha(13),Nle(14)]BBN(7-14), by condensation of a carboxylate of the bispidine backbone with the N-terminus of the peptide produced the bifunctional ligand 6. The radiocopper(II) complex of this bombesin-bispidine conjugate has a considerable hydrophilicity (log D(o/w) < -2.4), and this leads to a very fast blood clearance (blood: 0.28 +/- 0.02 SUV, 1 h p.i.), low liver tissue accumulation (liver: 1.20 +/- 0.27 SUV, 1 h p.i.), and rapid renal-urinary excretion (kidneys: 6.06 +/- 2.96 SUV, 1 h p.i.) as shown by biodistribution studies of 64Cu-6 in Wistar rats. Preliminary in vivo studies of 64Cu-6 in NMRI nu/nu mice, bearing the human prostate tumor PC-3 showed an accumulation of the conjugate in the tumor (2

  16. Bifunctional chelates of RH-105 and AU199 as potential radiotherapeutic agents

    Energy Technology Data Exchange (ETDEWEB)

    Droege, P.

    1997-03-01

    Research is presented on new bifunctional chelating ligand systems with stability on the macroscopic and radiochemical levels. The synthesis of the following complexes are described: rhodium 105, palladium 109, and gold 198.

  17. Microwave assisted facile one-pot synthesis of 188Re-complex using a tetrahydroborate exchange resin. A bifunctional chelating agent for radiopharmaceuticals

    International Nuclear Information System (INIS)

    A facile one-pot synthesis of 188Re-complex as a bifunctional chelating agent for the preparation of therapeutic radiopharmaceuticals was accomplished with good labeling yields and radiochemical purity by using a tetrahydroborate exchange resin as a reducing agent for a disulfide ligand as well as the [188Re] perrhenate ion under microwave irradiation. (author)

  18. p-carboxyethyl-phenylglyoxal bis(n-methylthiosemicarbazone) (CE-DTS), a bifunctional chelating agent for Tc-99m labeled monoclonal antibody

    International Nuclear Information System (INIS)

    In the search for bifunctional chelating agents (BCA) with better affinity, selectivity and stability as for Tc-99m, synthesis of a novel BCA containing di-thio-semicarbazone as for Tc-99m chelating site has offered interesting characteristics for the labeling of macromolecules. In the present paper, monoclonal IgG (MoAb) against human thyroglobulin was selected as a model and conditions for coupling, labeling reactions were tested along with immunological reactivity. CE-DTS was coupled to MoAb by the azido method and effect of conjugation on the MoAb immunoreactivity was followed by RIA. When CE-DTS was coupled to MoAb at the molar ratio of 1:1, no loss of its original immunoreactivity was observed. Tc-99m labeling, using the stannous ion reducing method, indicated the reaction pH as being a determinant parameter. The reducing agent prepared in tartrate buffer (pH 3) offered high yield and stable Tc-99m-CE-DTS-MoAb, as evidence by HPLC. In vivo studies in mice indicated percent of injected dose and blood clearance alike the I-131-MoAb. This good labeled state of Tc-99m-CE-DTS-MoAb was also demonstrated by using second antibody reaction in serum of mice. The newly synthesized CE-DTS offered good basis for the Tc-99m labeling of monclonal antibodies with preserved immunological properties, as desirable for the radioimmunodetection. Work with tumor related monoclonal antibodies is under progress

  19. 67Ga(NODASA): a new potential bifunctional radioligand for coupling to peptides

    International Nuclear Information System (INIS)

    A new bifunctional chelator NODASA (1,4,7-triazacyclononane-1-succinic acid-4,7-diacetic acid) has been synthesised and its Ga(III) complex was crystallographically characterized by X-ray diffraction. The complex showed to be stable in serum and in acidic conditions and its stability constant was determined using a competition method with an auxiliary ligand. The conjugation of Ga(NODASA) to a model aminoacidamide proved the feasibility of a prelabelling approach. (author)

  20. Synthesis, metal complexation and biological evaluation of a novel semi-rigid bifunctional chelating agent for 99mTc labelling

    OpenAIRE

    Le Gal, Julien; Michaud, Sandra; Gressier, Marie; Coulais, Yvon; Benoist, Eric

    2006-01-01

    A novel bifunctional chelating agent bearing an aromatic ring has been synthesised and characterised. This ligand formed well-defined oxorhenium complexes. The analogous 99mTcO-complex was obtained in an excellent yield with high radiochemical purity (>95%). The biodistribution of the 99mTo-complex after intravenous injection studied in normal rats showed that the activity was excreted mainly via renal-urinary pathway indicating its use for labelling peptides with 99mTc.

  1. Bifunctional alkylating agent-mediated MGMT-DNA cross-linking and its proteolytic cleavage in 16HBE cells.

    Science.gov (United States)

    Cheng, Jin; Ye, Feng; Dan, Guorong; Zhao, Yuanpeng; Wang, Bin; Zhao, Jiqing; Sai, Yan; Zou, Zhongmin

    2016-08-15

    Nitrogen mustard (NM), a bifunctional alkylating agent (BAA), contains two alkyl arms and can act as a cross-linking bridge between DNA and protein to form a DNA-protein cross-link (DPC). O(6)-methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme for alkyl adducts removal, is found to enhance cell sensitivity to BAAs and to promote damage, possibly due to its stable covalent cross-linking with DNA mediated by BAAs. To investigate MGMT-DNA cross-link (mDPC) formation and its possible dual roles in NM exposure, human bronchial epithelial cell line 16HBE was subjected to different concentrations of HN2, a kind of NM, and we found mDPC was induced by HN2 in a concentration-dependent manner, but the mRNA and total protein of MGMT were suppressed. As early as 1h after HN2 treatment, high mDPC was achieved and the level maintained for up to 24h. Quick total DPC (tDPC) and γ-H2AX accumulation were observed. To evaluate the effect of newly predicted protease DVC1 on DPC cleavage, we applied siRNA of MGMT and DVC1, MG132 (proteasome inhibitor), and NMS-873 (p97 inhibitor) and found that proteolysis plays a role. DVC1 was proven to be more important in the cleavage of mDPC than tDPC in a p97-dependent manner. HN2 exposure induced DVC1 upregulation, which was at least partially contributed to MGMT cleavage by proteolysis because HN2-induced mDPC level and DNA damage was closely related with DVC1 expression. Homologous recombination (HR) was also activated. Our findings demonstrated that MGMT might turn into a DNA damage promoter by forming DPC when exposed to HN2. Proteolysis, especially DVC1, plays a crucial role in mDPC repair. PMID:27342729

  2. Therapeutic potential of a non-steroidal bifunctional anti-inflammatory and anti-cholinergic agent against skin injury induced by sulfur mustard

    International Nuclear Information System (INIS)

    Sulfur mustard (bis(2-chloroethyl) sulfide, SM) is a highly reactive bifunctional alkylating agent inducing edema, inflammation, and the formation of fluid-filled blisters in the skin. Medical countermeasures against SM-induced cutaneous injury have yet to be established. In the present studies, we tested a novel, bifunctional anti-inflammatory prodrug (NDH 4338) designed to target cyclooxygenase 2 (COX2), an enzyme that generates inflammatory eicosanoids, and acetylcholinesterase, an enzyme mediating activation of cholinergic inflammatory pathways in a model of SM-induced skin injury. Adult SKH-1 hairless male mice were exposed to SM using a dorsal skin vapor cup model. NDH 4338 was applied topically to the skin 24, 48, and 72 h post-SM exposure. After 96 h, SM was found to induce skin injury characterized by edema, epidermal hyperplasia, loss of the differentiation marker, keratin 10 (K10), upregulation of the skin wound marker keratin 6 (K6), disruption of the basement membrane anchoring protein laminin 322, and increased expression of epidermal COX2. NDH 4338 post-treatment reduced SM-induced dermal edema and enhanced skin re-epithelialization. This was associated with a reduction in COX2 expression, increased K10 expression in the suprabasal epidermis, and reduced expression of K6. NDH 4338 also restored basement membrane integrity, as evidenced by continuous expression of laminin 332 at the dermal–epidermal junction. Taken together, these data indicate that a bifunctional anti-inflammatory prodrug stimulates repair of SM induced skin injury and may be useful as a medical countermeasure. - Highlights: • Bifunctional anti-inflammatory prodrug (NDH4338) tested on SM exposed mouse skin • The prodrug NDH4338 was designed to target COX2 and acetylcholinesterase. • The application of NDH4338 improved cutaneous wound repair after SM induced injury. • NDH4338 treatment demonstrated a reduction in COX2 expression on SM injured skin. • Changes of skin repair

  3. Therapeutic potential of a non-steroidal bifunctional anti-inflammatory and anti-cholinergic agent against skin injury induced by sulfur mustard

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yoke-Chen; Wang, James D.; Hahn, Rita A.; Gordon, Marion K.; Joseph, Laurie B. [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States); Heck, Diane E. [Department of Environmental Science, New York Medical College, Valhalla, NY (United States); Heindel, Ned D. [Department of Chemistry, Lehigh University, Bethlehem, PA (United States); Young, Sherri C. [Department of Chemistry, Muhlenberg College, Allentown, PA (United States); Sinko, Patrick J. [Department of Pharmaceutics, Rutgers University, Piscataway, NJ (United States); Casillas, Robert P. [MRIGlobal, Kansas City, MO (United States); Laskin, Jeffrey D. [Environmental and Occupational Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ (United States); Laskin, Debra L. [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States); Gerecke, Donald R., E-mail: gerecke@eohsi.rutgers.edu [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States)

    2014-10-15

    Sulfur mustard (bis(2-chloroethyl) sulfide, SM) is a highly reactive bifunctional alkylating agent inducing edema, inflammation, and the formation of fluid-filled blisters in the skin. Medical countermeasures against SM-induced cutaneous injury have yet to be established. In the present studies, we tested a novel, bifunctional anti-inflammatory prodrug (NDH 4338) designed to target cyclooxygenase 2 (COX2), an enzyme that generates inflammatory eicosanoids, and acetylcholinesterase, an enzyme mediating activation of cholinergic inflammatory pathways in a model of SM-induced skin injury. Adult SKH-1 hairless male mice were exposed to SM using a dorsal skin vapor cup model. NDH 4338 was applied topically to the skin 24, 48, and 72 h post-SM exposure. After 96 h, SM was found to induce skin injury characterized by edema, epidermal hyperplasia, loss of the differentiation marker, keratin 10 (K10), upregulation of the skin wound marker keratin 6 (K6), disruption of the basement membrane anchoring protein laminin 322, and increased expression of epidermal COX2. NDH 4338 post-treatment reduced SM-induced dermal edema and enhanced skin re-epithelialization. This was associated with a reduction in COX2 expression, increased K10 expression in the suprabasal epidermis, and reduced expression of K6. NDH 4338 also restored basement membrane integrity, as evidenced by continuous expression of laminin 332 at the dermal–epidermal junction. Taken together, these data indicate that a bifunctional anti-inflammatory prodrug stimulates repair of SM induced skin injury and may be useful as a medical countermeasure. - Highlights: • Bifunctional anti-inflammatory prodrug (NDH4338) tested on SM exposed mouse skin • The prodrug NDH4338 was designed to target COX2 and acetylcholinesterase. • The application of NDH4338 improved cutaneous wound repair after SM induced injury. • NDH4338 treatment demonstrated a reduction in COX2 expression on SM injured skin. • Changes of skin repair

  4. Macrocyclic bifunctional chelating agents

    Science.gov (United States)

    Meares, Claude F.; DeNardo, Sally J.; Cole, William C.; Mol, Min K.

    1987-01-01

    A copper chelate conjugate which is stable in human serum. The conjugate includes the copper chelate of a cyclic tetraaza di-, tri-, or tetra-acetic acid, a linker attached at one linker end to a ring carbon of the chelate, and a biomolecule joined at the other end of the linker. The conjugate, or the linker-copper chelate compound used in forming the conjugate, are designed for use in diagnostic and therapeutic applications which involve Cu(II) localization via the systemic route.

  5. Remarkable red-shift of upconversion luminescence and anti-ferromagnetic coupling in NaLuF4:Yb3+/Tm3+/Gd3+/Sm3+ bifunctional microcrystals

    Institute of Scientific and Technical Information of China (English)

    胡仕刚; 刘云新; 吴笑峰; 唐志军; 李志明; 颜焕元; 陈增辉; 胡盼; 余意

    2016-01-01

    Lanthanide doped bifunctional materials are potentially important for developing multifunctional devices. Here, NaLuF4:Yb3+/Tm3+/Gd3+/Sm3+ optical-magnetic bifunctional microcrystals were successfully synthesized by hydrothermal method, which could emit ~480 nm blue light from the1G4→3H6 electronic transition and ~800 nm infrared light from the3H4→3H6electronic transition of Tm3+ ion, under the excitation of 980 nm infrared light. By doping Sm3+ ion into NaLuF4:Yb3+/Tm3+/Gd3+, the infrared emission peak centered at 800 nm would shift obviously to longer wavelength. This indicated that Sm3+ ion could efficiently tune the energy level gaps of Tm3+ ions in NaLuF4 host which was demonstrated based on the crystal field theory. In addition, these NaLuF4:Yb3+/Tm3+/Gd3+/Sm3+ microcrystals presented unique ferromagnetic property instead of usually reported paramagnetic prop-erty. Importantly, the ferromagnetic property decreased with increasing the concentration of Gd3+ ion. This was in good agreement with Swift’s theoretical investigation that the coexistence of light rare earth (Gd3+) and heavy rare earth (Yb3+/Tm3+) would lead to the anti-ferromagnetic coupling in the sub-lattices.

  6. Synthesis and evaluation of two new bifunctional carboxymethylated tetraazamacrocyclic chelating agents for protein labeling with indium-111

    Energy Technology Data Exchange (ETDEWEB)

    Ruser, G.; Ritter, W.; Maecke, H.R. (Univ. Hospital Basel (Switzerland))

    1990-09-01

    The synthesis of two new N- and C-functionalized tetraazamacrocyclic ligands intended to be covalently linked to biomolecules like monoclonal antibodies and to bind the gamma-emitting isotope indium-111 in a thermodynamically and/or kinetically inert way is described. 12-(p-Nitrobenzyl)-1,4,7,10-tetraazacyclotridecane-1,4,7,10-tetraa cetic acid (L1) was synthesized by means of bimolecular cyclization with the appropriate malonic acid diethyl ester and triethylenetetraamine, followed by reduction with diborane and alkylation of the cyclic tetraamine with bromoacetic acid. The corresponding triscarboxymethylated ligand L2 was made by statistical alkylation of the tetraamine. Both ligands fulfill the criteria for antibody labeling using the bifunctional chelate approach, namely fast chelate formation, high radiochemical yield, and high stability under physiological conditions. Surprisingly the heptadentate ligand L2 confers higher stability to In3+ and exhibits faster complex formation than octadentate L1. 13C NMR spectra in solution indicate that the difference in stability is not due to incomplete coordination of all four carboxylate groups in In-L1.

  7. Synthesis and characterization of {sup 99m}Tc- and {sup 188}Re-complexes with a diamido-dihydroxymethylenephosphine-based bifunctional chelating agent (N{sub 2}P{sub 2}-BFCA)

    Energy Technology Data Exchange (ETDEWEB)

    Kothari, K.K. E-mail: kanchan@apsara.barc.ernet.in; Gali, H.; Prabhu, K.R.; Pillarsetty, N.; Owen, N.K.; Katti, K.V.; Hoffman, T.J.; Volkert, W.A

    2002-01-01

    A diamido-dihydroxymethylenephosphine (N{sub 2}P{sub 2}) bifunction chelating agent (BFCA) was shown to form well-defined {sup 99m}Tc- and {sup 188}Re-chelate structures. The 4, 4-bis [bis-hydroxymethyl-phosphonyl-propylcarbonmoyl]-butyric acid bifunctional chelating agent (N{sub 2}P{sub 2}-BFCA) formed stable complexes with {sup 99m}Tc and {sup 188}Re in >95% yield with high radiochemical purity (RCP). The biodistribution of the {sup 99m}Tc- and {sup 188}Re-N{sub 2}P{sub 2}-BFCAs after intravenous injection studied in normal mice showed the activity was excreted primarily via renal-urinary pathway indicating their use for labeling peptides with {sup 99m}Tc and {sup 188}Re.

  8. Complex between lignin and a Ti-based coupling agent

    DEFF Research Database (Denmark)

    Rasmussen, Jonas Stensgaard; Barsberg, Søren Talbro; Felby, Claus

    2014-01-01

    coating formulations would have a better performance if the adhesion to wood could be improved. In the present work, the chemical interaction between a titanium-based coupling agent, isopropyl triisostearoyl titanate (titanium agent, TA) and lignin has been studied by means of attenuated total reflectance...... between TA and lignin....

  9. Utility of tumor-avid photosensitizers in developing bifunctional agents for tumor imaging and/or phototherapy

    Science.gov (United States)

    Pandey, Suresh K.; Chen, Yihui; Zawada, Robert H.; Oseroff, Allan; Pandey, Ravindra K.

    2006-02-01

    HPPH (a chlorophyll-a analog) was linked with a cyanine dye and the resulting conjugate was found to be an efficient tumor imaging (fluorescence imaging) and photosensitizing agent (PDT). Our preliminary results suggest that tumor-avid porphyrin-based compounds can be used as vehicles for delivering the desired fluorophores to tumor for fluorescence imaging. In an early diagnosis of microscopic lesions in pre-clinical studies (C3H mice implanted with RIF tumors) the HPPH-cyanine dye conjugate showed tumor-imaging capability (λ ex: 780 nm, λ em: 860 nm) at the non- therapeutic doses that are 100 fold lower than those used therapeutically. Compared to the cyanine dye, the corresponding HPPH-conjugate showed enhanced long-term tumor imaging ability.

  10. Gadolinium Nanoparticles Conjugated with Therapeutic Bifunctional Chelate as a Potential T1 Theranostic Magnetic Resonance Imaging Agent.

    Science.gov (United States)

    Kang, Min-Kyoung; Lee, Gang Ho; Jung, Ki-Hye; Jung, Jae-Chang; Kim, Hee-Kyung; Kim, Yeon-Hee; Lee, Jongmin; Ryeom, Hun-Kyu; Kim, Tae-Jeong; Chang, Yongmin

    2016-05-01

    This work is directed toward the synthesis of two types of gadolinium oxide nanoparticles (Gd-oxide NPs), abbreviated as Gd@SiO2-DO3A and Gd@SiO2-DO2A-BTA, with diameters of 50-60 nm. The synthesis involves sequential coating of Gd-oxide NPs with tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES), followed by functionalization of the aminopropylsilane group with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) or 1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid conjugates of benzothiazoles (DO3A-BTA). Gd@SiO2-DO3A and Gd@SiO2-DO2A-BTA exhibit high water solubility and colloidal stability. The r1 relaxivities of both Gd@SiO2-DO3A and Gd@SiO2-DO2A-BTA are higher than those of the corresponding low-molecular-weight magnetic resonance imaging contrast agents (MRI CAs), and their r2/r1 ratios are close to 1, indicating that both can be used as potential T1 MRI CAs. Biodistribution studies demonstrated that Gd@SiO2-DO2A-BTA was excreted via both hepatobiliary and renal pathways. Gd@SiO2-DO2A-BTA exhibits a strong intracellular uptake property in a series of tumor cell lines, and has significant anticancer characteristics against cell lines such as SK-HEP-1, MDA-MB-231, HeLa, and Hep-3B. PMID:27305813

  11. Direct and Highly Selective Conversion of Synthesis Gas into Lower Olefins: Design of a Bifunctional Catalyst Combining Methanol Synthesis and Carbon-Carbon Coupling.

    Science.gov (United States)

    Cheng, Kang; Gu, Bang; Liu, Xiaoliang; Kang, Jincan; Zhang, Qinghong; Wang, Ye

    2016-04-01

    The direct synthesis of lower (C2 to C4 ) olefins, key building-block chemicals, from syngas (H2  /CO), which can be derived from various nonpetroleum carbon resources, is highly attractive, but the selectivity for lower olefins is low because of the limitation of the Anderson-Schulz-Flory distribution. We report that the coupling of methanol-synthesis and methanol-to-olefins reactions with a bifunctional catalyst can realize the direct conversion of syngas to lower olefins with exceptionally high selectivity. We demonstrate that the choice of two active components and the integration manner of the components are crucial to lower olefin selectivity. The combination of a Zr-Zn binary oxide, which alone shows higher selectivity for methanol and dimethyl ether even at 673 K, and SAPO-34 with decreased acidity offers around 70 % selectivity for C2 -C4 olefins at about 10 % CO conversion. The micro- to nanoscale proximity of the components favors the lower olefin selectivity. PMID:26961855

  12. An Efficient Bi-functional Electrocatalyst Based on Strongly Coupled CoFe2O4/Carbon Nanotubes Hybrid for Oxygen Reduction and Oxygen Evolution

    International Nuclear Information System (INIS)

    Cobalt ferrite (CoFe2O4) spinel oxide is a promising electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the catalytic activity of CoFe2O4 is limited by its poor electronic conductivity. In this study, CoFe2O4 strongly coupled with carbon nanotubes (CoFe2O4/CNTs) hybrid has been fabricated to address this issue. The as-synthesized CoFe2O4/CNTs hybrid exhibits excellent electrocatalytic activities for both the ORR and OER in alkaline solution. The onset potential of CoFe2O4/CNTs for ORR is −0.124 V (vs. Ag/AgCl), which is much higher than that of the CoFe2O4 + CNTs mixture (−0.259 V). Meanwhile, the CoFe2O4/CNTs hybrid shows much higher activity for OER as compared to the CoFe2O4 + CNT mixture. The onset potential of the former is 54 mV higher than that of the latter. The CoFe2O4/CNTs also holds high stability for both the ORR and OER, outperforming the CoFe2O4 + CNTs mixture. The excellent electrocatalytic activity and stability of the CoFe2O4/CNTs hybrid for both the ORR and OER make it a potential bi-functional electrocatalysts for metal-air batteries

  13. Coupling of a bifunctional peptide R13 to OTMCS-PEI copolymer as a gene vector increases transfection efficiency and tumor targeting

    Directory of Open Access Journals (Sweden)

    Lv H

    2014-03-01

    Full Text Available Hui Lv,1,* Qing Zhu,1,* Kewu Liu,2 Manman Zhu,1 Wenfang Zhao,1 Yuan Mao,1 Kehai Liu1 1Department of Biopharmaceutics, College of Food Science and Technology, Shanghai Ocean University, Shanghai, People's Republic of China; 2Heilongjiang Forest By-Product and Speciality Institute, Mudanjiang, People's Republic of China *These authors contributed equally to this work Background: A degradable polyethylenimine (PEI derivative coupled to a bifunctional peptide R13 was developed to solve the transfection efficiency versus cytotoxicity and tumor-targeting problems of PEI when used as a gene vector. Methods: We crossed-linked low molecular weight PEI with N-octyl-N-quaternary chitosan (OTMCS to synthesize a degradable PEI derivative (OTMCS-PEI, and then used a bifunctional peptide, RGDC-Tat (49–57 called R13 to modify OTMCS-PEI so as to prepare a new gene vector, OTMCS-PEI-R13. This new gene vector was characterized by various physicochemical methods. Its cytotoxicity and gene transfection efficiency were also determined both in vitro and in vivo. Results: The vector showed controlled degradation and excellent buffering capacity. The particle size of the OTMCS-PEI-R13/DNA complexes was around 150–250 nm and the zeta potential ranged from 10 mV to 30 mV. The polymer could protect plasmid DNA from being digested by DNase I at a concentration of 23.5 U DNase I/µg DNA. Further, the polymer was resistant to dissociation induced by 50% fetal bovine serum and 400 µg/mL sodium heparin. Compared with PEI 25 kDa, the OTMCS-PEI-R13/DNA complexes showed higher transfection efficiency both in vitro and in vivo. Further, compared with OTMCS-PEI, distribution of OTMCS-PEI-R13 at tumor sites was markedly enhanced, indicating the tumor-targeting specificity of R13. Conclusion: OTMCS-PEI-R13 could be a potential candidate as a safe and efficient gene delivery carrier for gene therapy. Keywords: nonviral gene vector, polyethylenimine, R13, transfection efficiency

  14. Nature of the bifunctional chelating agent used for radioimmunotherapy with yttrium-88 monoclonal antibodies: critical factors in determining in vivo survival and organ toxicity

    International Nuclear Information System (INIS)

    One factor that is critical to the potential effectiveness of radioimmunotherapy is the design of radiometal-chelated antibodies that will be stable in vivo. Stability in vivo depends on the condition that both the chelate linkage and radiolabeling procedures not alter antibody specificity and biodistribution. In addition, synthesis and selection of the chelating agent is critical for each radiometal in order to prevent inappropriate release of the radiometal in vivo. In the present study, we compare the in vivo stability of seven radioimmunoconjugates that use different polyaminocarboxylate chelating agents to complex yttrium-88 to the mouse anti-human interleukin-2 receptor monoclonal antibody, anti-Tac. Chelate linkage and radiolabeling procedures did not alter the immunospecificity of anti-Tac. In order to assess whether yttrium was inappropriately released from the chelate-coupled antibody in vivo, iodine-131-labeled and yttrium-88 chelate-coupled antibodies were simultaneously administered to the same animals to correlate the decline in yttrium and radioiodinated antibody activity. The four stable yttrium-88 chelate-coupled antibodies studied displayed similar iodine-131 and yttrium-88 activity, indicating minimal elution of yttrium-88 from the complex. In contrast, the unstable yttrium-88 chelate-coupled antibodies had serum yttrium-88 activities that declined much more rapidly than their iodine-131 activities, suggesting loss of the radiolabel yttrium-88 from the chelate. Furthermore, high rates of yttrium-88 elution correlated with deposition in bone. Four chelating agents emerged as promising immunotherapeutic reagents: isothiocyanate benzyl DTPA and its derivatives 1B3M, MX, and 1M3B

  15. Aryl diazonium salts new coupling agents and surface science

    CERN Document Server

    Chehimi, Mohamed Mehdi

    2012-01-01

    Diazonium compounds are employed as a new class of coupling agents to link polymers, biomacromolecules, and other species (e. g. metallic nanoparticles) to the surface of materials. The resulting high performance materials show improved chemical and physical properties and find widespread applications. The advantage of aryl diazonium salts compared to other surface modifiers lies in their ease of preparation, rapid (electro)reduction, large choice of reactive functional groups, and strong aryl-surface covalent bonding.This unique book summarizes the current knowledge of the surface and

  16. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt

  17. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yuan, Jianmin [College of Materials Engineering, Hunan University, Changsha, 410082 (China); Tan, Ligang [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082 (China); Wang, Shuangyin [State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wu, Zhenjun, E-mail: wooawt@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China)

    2015-08-15

    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  18. Preparation of {sup 105}Rh labeled monoclonal antibody (MAb B72.3) using aminobenzylpropyleneamineoxime as the bifunctional chelating agent; comparison to {sup 131}I labeled MAb B72.3

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, M. [Bhabha Atomic Research Centre, Bombay (India). Isotope Div.; Schlemper, E.O.; Jurisson, S.S. [Missouri Univ., Columbia, MO (United States). Dept. of Chemistry; Ketring, A.R. [Missouri Univ. Research Reactor, Columbia, MO (United States); Volkert, W.A. [Missouri Univ., Columbia, MO (United States). Radiology Research; H.S. Truman Memorial VA Hospital, Columbia, MO (United States); Corlija, M. [H.S. Truman Memorial VA Hospital, Columbia, MO (United States)

    1999-07-01

    Monoclonal antibody(MAb) B72.3 was labeled with {sup 105}Rh using aminobenzylpropyleneamineoxime (PnAO-{phi}-NH{sub 2}) as the bifunctional chelating agent. {sup 105}Rh-PnAO-{phi}-NH{sub 2} was formed at {proportional{underscore}to} 80 C at pH 5-6 and purified by extraction into chloroform. The excess unreacted ligand was retained in the aqueous phase by addition of Cu{sup 2+} ions by forming a charged complex. The amine group on {sup 105}Rh complex was activated and conjugated with MAb at pH 8.5 {proportional{underscore}to}90% complexation and 40-60% conjugation were realised. Radiolabeled antibody was purified by gel filtration. B72.3 MAb was labeled with {sup 131}I and used for comparison of biodistribution in normal mice. (orig.)

  19. Bifunctional alkaline oxygen electrodes

    Science.gov (United States)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  20. Modification of eucalyptus pulp fiber using silane coupling agents with aliphatic side chains of different length

    Science.gov (United States)

    The objective of this work was to evaluate the effect of three silane coupling agents with different aliphatic chain lengths on the hydrophobicity of eucalyptus pulp fiber. The three silanes coupling agents used (isobutyltrimethoxysilane, methyltrimethoxysilane, and n-octyltriethoxysilane [OTES]) we...

  1. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Science.gov (United States)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng; Yuan, Jianmin; Tan, Ligang; Wang, Shuangyin; Wu, Zhenjun

    2015-08-01

    A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  2. Tight bifunctional hierarchical catalyst.

    Science.gov (United States)

    Højholt, Karen T; Vennestrøm, Peter N R; Tiruvalam, Ramchandra; Beato, Pablo

    2011-12-28

    A new concept to prepare tight bifunctional catalysts has been developed, by anchoring CoMo(6) clusters on hierarchical ZSM-5 zeolites for simultaneous use in HDS and hydrocracking catalysis. The prepared material displays a significant improved activity in HDS catalysis compared to the impregnated counterpart. PMID:22048337

  3. A Loosely Coupled Control Architecture Based on Agent and CORBA for Multiple Robots

    Institute of Scientific and Technical Information of China (English)

    Wu Shandong(吴山东); Chen Yimin; He Yongyi

    2003-01-01

    With the rapid development of information technology, adopting advanced distributed computing technology to construct robot control system is becoming an effective approach gradually. This paper proposes a distributed loosely coupled software architecture based on Agent and CORBA to control multiple robots. This model provides the robot user with agent control units at the semantic level and CORBA provides function interfaces to agent at the syntax level, which shows a good adaptability, flexibility and transparence.

  4. Coherent Pattern Prediction in Swarms of Delay-Coupled Agents

    Science.gov (United States)

    Mier-Y-Teran-Romero, Luis; Forgoston, Eric; Scwartz, Ira

    2013-03-01

    We consider a general swarm model of self-propelling particles interacting through a pairwise potential in the presence of a fixed communication time delay. Previous work has shown that swarms with communication time delays and noise may display pattern transitions that depend on the size of the coupling amplitude. We extend these results by completely unfolding the bifurcation structure of the mean field approximation. Our analysis reveals a direct correspondence between the different dynamical behaviors found in different regions of the coupling-time delay plane with the different classes of simulated coherent swarm patterns. We derive the spatio-temporal scales of the swarm structures, and also demonstrate how the complicated interplay of coupling strength, time delay, noise intensity, and choice of initial conditions can affect the swarm. In addition, when adding noise to the system, we find that for sufficiently large values of the coupling strength and/or the time delay, there is a noise intensity threshold that forces a transition of the swarm from a misaligned state into an aligned state. We show that this alignment transition exhibits hysteresis when the noise intensity is taken to be time dependent. Office of Naval Research, NIH (LMR and IBS) and NRL (EF)

  5. EFFECTS OF COUPLING AGENTS ON THE CRYSTALLIZATION BEHAVIOR OF PP/T-ZnOw COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The objectives of this paper are to understand the crystallization behavior of polypropylene (PP) composites with surface modified tetra-needle-shaped zinc oxide whisker (T-ZnOw). T-ZnOw was surface modified with different coupling agents, such as silane coupling agents (KH-550, KH-560) and titanate coupling agent (NDZ-105), in order to improve the compatibility between PP and T-ZnOw. DSC and POM were used to characterize the melt and crystallization behavior and the crystalline structures of the composites, respectively. The results show that the surface modified T-ZnOw acts as a nucleating agent of PP crystallization, depending on the coupling agent used for modification. KH-550 and KH-560 have more apparent role in improving the interfacial interaction than NDZ-105 and induce PP crystallization at higher temperature and with smaller spherulites size. The results also suggest that the crystallization behavior depends on not only the content of coupling agent, but also the content of the surface modified T-ZnOw used in the composites.

  6. Platinum(II) as bifunctional linker in antibody-drug conjugate formation: coupling of a 4-nitrobenzo-2-oxa-1,3-diazole fluorophore to trastuzumab as a model.

    Science.gov (United States)

    Waalboer, Dennis C J; Muns, Joey A; Sijbrandi, Niels J; Schasfoort, Richard B M; Haselberg, Rob; Somsen, Govert W; Houthoff, Hendrik-Jan; van Dongen, Guus A M S

    2015-05-01

    The potential of platinum(II) as a bifunctional linker in the coordination of small molecules, such as imaging agents or (cytotoxic) drugs, to monoclonal antibodies (mAbs) was investigated with a 4-nitrobenzo-2-oxa-1,3-diazole (NBD) fluorophore and trastuzumab (Herceptin™) as a model antibody. The effect of ligand and reaction conditions on conjugation efficiency was explored for [Pt(en)(L-NBD)Cl](NO3 ) (en=ethylenediamine), with L=N-heteroaromatic, N-alkyl amine, or thioether. Conjugation proceeded most efficiently at pH 8.0 in the presence of NaClO4 or Na2 SO4 in tricine or HEPES buffer. Reaction of N-coordinated complexes (20 equiv) with trastuzumab at 37 °C for 2 h, followed by removal of weakly bound complexes with excess thiourea, afforded conjugates with an NBD/mAb ratio of 1.5-2.9 that were stable in phosphate-buffered saline at room temperature for at least 48 h. In contrast, thioether-coordinated complexes afforded unstable conjugates. Finally, surface plasmon resonance analysis showed no loss in binding affinity of trastuzumab after conjugation. PMID:25809281

  7. Hydrogenolysis of cellulose to C4-C7 alcohols over bi-functional CuO-MO/Al2O3 (M=Ce, Mg, Mn, Ni, Zn) catalysts coupled with methanol reforming reaction.

    Science.gov (United States)

    Wu, Yanhua; Gu, Fangna; Xu, Guangwen; Zhong, Ziyi; Su, Fabing

    2013-06-01

    This work demonstrates the efficient hydrogenolysis of cellulose to C4-C7 alcohols and gas products (reaction 1) by coupling it with the reforming reaction of methanol (reaction 2) over bi-functional CuO-based catalysts. In this process, the CuO-based catalysts catalyze both the reactions 1 and 2, and the in situ regenerated H2 in the reaction 2 is used for the reaction 1. A series of CuO-MO/Al2O3 (M=Ce, Mg, Mn, Ni, Zn) catalysts were prepared by the co-precipitation method. Among these catalysts, CuO-ZnO/Al2O3 exhibited the highest activity to generate a high cellulose conversion of 88% and a high C4-C7 alcohols content above 95% in the liquid products. The CuO-ZnO/Al2O3 catalyst was stable under the reaction conditions and reusable after 4 runs. This work provides a cost-effective route to convert abundant renewable cellulose to liquid fuels. PMID:23591118

  8. Enhancement of interfacial properties of basalt fiber reinforced nylon 6 matrix composites with silane coupling agents

    Directory of Open Access Journals (Sweden)

    2010-10-01

    Full Text Available In this work solution surface treatment was applied for producing basalt fiber reinforced PA6 matrix composites. Beyond scanning electron microscopy, static and dynamic mechanical tests, dynamic mechanical analysis of composites was used for qualifying the interfacial adhesion in a wide temperature range. The loss factor peak height of loss factor is particularly important, because it is in close relationship with the mobility of polymer molecular chain segments and side groups, hence it correlates with the number and strength of primary or secondary bondings established between the matrix and the basalt fibers. It was proven, that the interfacial adhesion between basalt fibers and polyamide can be largely improved by the application of silane coupling agents in the entire usage temperature range of composites. The presence of coupling agents on the surface of basalt fibers was proven by Fourier transform infrared spectroscopy. The best results were obtained by 3-glycidoxypropyltrimethoxysilane coupling agent.

  9. Surface Modification of Fire-retardant Asphalt with Silane Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    CHEN Huiqiang; TANG Boming

    2012-01-01

    The theory and approach of the surface modified of asphalt fire-retardant with silane coupling agent were introduced,The optimum silane dosage was determined,and the structure and properties of the asphalt fire-retardant before and after the surface modification were characterized by infrared spectrum and thermo gravimetric analysis.The dispersion effect of asphalt fire-retardant was studied.The influence of the surface modification on the hydrophilicity and lipophilicity of the asphalt fire-retardant was analyzed.The experimental results showed that there were physical and chemical interactions between the silane coupling agent and the asphalt fire-retardant,which reduced the surface polarity of the asphalt fire retardant.The optimum silane coupling agent dosage was 0.95% of the asphalt fire retardant.The surface modification improved the thermal stability,dispersibility and lipophilicity of the asphalt fire retardant,which enhanced the compatibility between asphalt fire retardant and asphalt.

  10. Thermal behavior and transformation kinetics of titanium dioxide nanocrystallites prepared by coupling agents

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.C. [School of Dentistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Wang, Y.T. [Department of Medical Research and Education, Chen Hsin General Hospital, 45 Cheng-Hsin Street, Pai-Tou, Taipei 11220, Taiwan (China); Shih, C.J., E-mail: cjshih@kmu.edu.t [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan1st Road, Kaohsiung 80708, Taiwan (China)

    2010-02-04

    Coupling agents have been widely used to retard the sintering of silver paste and minimize co-firing defects due to densification mismatch between silver and dielectrics. The thermal-decomposition and crystallization behavior of the coupling agent is a subject of great concern. To elucidate what is responsible for the oxidation, Ti organometallic compounds were calcined at different temperatures (350, 400, 500, 600 {sup o}C) for 2 h and the crystallization behavior was determined by X-ray diffraction (XRD). The activation energy for crystallization of coupling agents was studied by using isothermal methods. According to the quantitative XRD method, the values calculated by the Johnson-Mehi-Avrami equation are 134.9 kJ mol{sup -1}. The growth morphology parameters are 1.061, 0.915, 1.016 respectively. Combining the results of DTA, XRD and TEM, it is found that formation of nanocrystallized titania accompanies the combustion of organometallic compounds.

  11. Thermal behavior and transformation kinetics of titanium dioxide nanocrystallites prepared by coupling agents

    International Nuclear Information System (INIS)

    Coupling agents have been widely used to retard the sintering of silver paste and minimize co-firing defects due to densification mismatch between silver and dielectrics. The thermal-decomposition and crystallization behavior of the coupling agent is a subject of great concern. To elucidate what is responsible for the oxidation, Ti organometallic compounds were calcined at different temperatures (350, 400, 500, 600 oC) for 2 h and the crystallization behavior was determined by X-ray diffraction (XRD). The activation energy for crystallization of coupling agents was studied by using isothermal methods. According to the quantitative XRD method, the values calculated by the Johnson-Mehi-Avrami equation are 134.9 kJ mol-1. The growth morphology parameters are 1.061, 0.915, 1.016 respectively. Combining the results of DTA, XRD and TEM, it is found that formation of nanocrystallized titania accompanies the combustion of organometallic compounds.

  12. Cluster Consensus of Nonlinearly Coupled Multi-Agent Systems in Directed Graphs

    Science.gov (United States)

    Lu, Xiao-Qing; Francis, Austin; Chen, Shi-Hua

    2010-05-01

    We investigate the cluster consensus problem in directed networks of nonlinearly coupled multi-agent systems by using pinning control. Depending on the community structure generated by the group partition of the underlying digraph, various clusters can be made coherently independent by applying feedback injections to a fraction of the agents. Sufficient conditions for cluster consensus are obtained using algebraic graph theory and matrix theory and some simulations results are included to illustrate the method.

  13. Introducing new 99m-Tc-bifunctional radiopharmaceutical containing dithiosemicarbazone chelate group

    International Nuclear Information System (INIS)

    In our attempt to develop 99m-Tc-Bifunctional Radiopharmaceuticals (BR) of biomolecules, our interest has been focussed on the di-thiosemicarbazone chelating group (DTS); its coordination moiety allows a 1:1 complex with a tetravalent TcO2+, generating a neutral chelate of great stability and compactness. For ligand containing S N coordination, satisfactory labeling has been achieved at pH 5-6, in the presence of Sn-Resin. Based on the above mentioned, the use of DTS is tested in two different modalities by selecting glucose and albumin as the biomolecules of interest. The synthesis of a glucosone-1,2-bis (thiosemicarbazone) (Glu-DTS) and upon its labelling, the 99m-Tc-Glu-DTS was tested in animals. Scintigraphic studies revealed high activity in the brain and heart. This result offered strong support for the use of DTS as a bifunctional chelating agent (BCA). DTS-COOH and DTS-NH2 were synthesized for the coupling with biomolecules. As a first trial, they were coupled with albumin and their functionality proven. The results gathered provided conclusive evidence for the remarkable characteristic of DTS as a basic structure for the development of 99m-Tc-RP

  14. Coupling of anionic wetting agents to dust of sulfide ores by dropping liquid method

    Institute of Scientific and Technical Information of China (English)

    WU Chao; OU Jia-cai; ZHOU Bo

    2005-01-01

    By using the experimental approach of dropping liquid, the coupling of three anionic wetting agents with ten dust samples of sulfide ores was studied, and particularly the wetting effects of the wetting agents on the sulfide dust influenced by factors of agent concentration and sulfate additive in the wetting agent solutions were investigated. The results show that when the solution temperature is about 20 ℃, all the selected wetting agents are effective to most dust samples, but the effect is different. Wetting agents are more effective to the dust which is difficult to be wetted. Wetting agent solution with sodium sulfate can improve the wetting ability of sulfide dust. For sodium dodecyl benzene sulfonate, the suitable concentration of sodium sulfate is 1-2 mmol/L. The cost of wetting agents can be reduced because the sodium sulfate is much cheaper than many surfactants. Since the dust of sulfide ores is composed of various minerals and elements, the whole effect of depressing dust should be considered while innovating a wetting agent.

  15. Synthesis of novel bis(perfluorophenyl azides) coupling agents: Evaluation of their performance by crosslinking of poly(ethylene oxide)

    KAUST Repository

    Mehenni, Hakim

    2011-11-01

    Novel bis(perfluorophenyl azides) coupling agents, containing spacer arms from ethylene or ethylene glycol subunits, were successfully synthesized. Nitrenes photogenerated from these novel bis(PFPA) coupling agents were applied successfully to the cross-linking of poly(ethylene oxide) (PEO10,000) in either aqueous medium or at the solid state, thus, we demonstrated the potential of these bis(PFPA) molecules as promising coupling agents in surface engineering. © 2011 Elsevier Ltd. All rights reserved.

  16. Assessment of covalent bond formation between coupling agents and wood by FTIR spectroscopy and pull strength tests

    DEFF Research Database (Denmark)

    Rasmussen, Jonas Stensgaard; Barsberg, Søren Talbro; Venås, Thomas Mark; Felby, Claus

    2014-01-01

    In the focus was the question whether metal alkoxide coupling agents – titanium, silane, and zirconium – form covalent bonds to wood and how they improve coating adhesion. In a previous work, a downshift of the lignin infrared (IR) band ∼1600 cm-1 was shown to be consistent with the formation of...... ether linkages between lignin and titanium coupling agent. In the present work, changes were found in the attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectra of lignin and wood mixed with silane, and titanium coupling agents, and to a lesser extent for a zirconium coupling agent. This...

  17. Enhancing indium tin oxide (ITO) thin film adhesiveness using the coupling agent silane

    International Nuclear Information System (INIS)

    The coupling agent γ-mercapto propyl trimethoxy silane (WD-80) was used to enhance the adhesiveness of the indium tin oxide (ITO) thin film, which was prepared on a glass substrate using the sol-gel method. The nano-scratching test, XRD, TEM, SEM, and UV-vis spectrophotometer were employed to examine film adhesion, crystal structure, surface morphology, and transmittance. The results indicated that silane coupling agent, used in low concentration, did not change the film structure but increased the critical load of the film by 49%, from 4.16 mN to 6.20 mN, when the film was peeled off from the substrate. The principle by which the coupling agent works is discussed. In addition to increasing with the light wavelength, the average transmittance of the film in the visible range varied from 78.9% to 83.6%. Moreover, as a function of the WD-80 silane coupling agent, the film exhibited a high smoothness and density due to the orderly arrangement of particles.

  18. Development and Evaluation of Novel Coupling Agents for Kenaf-Fiber-Reinforced Unsaturated Polyester Composites

    Science.gov (United States)

    Ren, Xiaofeng

    Natural fibers are gaining popularity as reinforcement materials for thermoset resins over the last two decades. Natural fibers are inexpensive, abundant, renewable and environmentally friendly. Kenaf fibers are one of the natural fibers that can potentially be used for reinforcing unsaturated polyester (UPE). As a polymer matrix, UPE enjoys a 40% market share of all the thermoset composites. This widespread application is due to many favorable characteristics including low cost, ease of cure at room temperature, ease of molding, a good balance of mechanical, electrical and chemical properties. One of the barriers for the full utilization of the kenaf fiber reinforced UPE composites, however, is the poor interfacial adhesion between the natural fibers and the UPE resins. The good interfacial adhesion between kenaf fibers and UPE matrix is essential for generating the desired properties of kenaf-UPE composites for most of the end applications. Use of a coupling agent is one of the most effective ways of improving the interfacial adhesion. In this study, six novel effective coupling agents were developed and investigated for kenaf-UPE composites: DIH-HEA, MFA, NMA, AESO-DIH, AESO-MDI, and AESO-PMDI. All the coupling agents were able to improve the interfacial adhesion between kanaf and UPE resins. The coupling agents were found to significantly enhance the flexural properties and water resistance of the kenaf-UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed all the coupling agents were covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed the improved interfacial adhesion between kanaf fibers and UPE resins.

  19. In Situ Coupling of Strung Co4N and Intertwined N-C Fibers toward Free-Standing Bifunctional Cathode for Robust, Efficient, and Flexible Zn-Air Batteries.

    Science.gov (United States)

    Meng, Fanlu; Zhong, Haixia; Bao, Di; Yan, Junmin; Zhang, Xinbo

    2016-08-17

    Flexible power sources with high energy density are crucial for the realization of next-generation flexible electronics. Theoretically, rechargeable flexible zinc-air (Zn-air) batteries could provide high specific energy, while their large-scale applications are still greatly hindered by high cost and resources scarcity of noble-metal-based oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) electrocatalysts as well as inferior mechanical properties of the air cathode. Combining metallic Co4N with superior OER activity and Co-N-C with perfect ORR activity on a free-standing and flexible electrode could be a good step for flexible Zn-air batteries, while lots of difficulties need to be overcome. Herein, as a proof-of-concept experiment, we first propose a strategy for in situ coupling of strung Co4N and intertwined N-C fibers, by pyrolyzation of the novel pearl-like ZIF-67/polypyrrole nanofibers network rooted on carbon cloth. Originating from the synergistic effect of Co4N and Co-N-C and the stable 3D interconnected conductive network structure, the obtained free-standing and highly flexible bifunctional oxygen electrode exhibits excellent electrocatalytic activity and stability for both OER and ORR in terms of low overpotential (310 mV at 10 mA cm(-2)) for OER, a positive half-wave potential (0.8 V) for ORR, and a stable current density retention for at least 20 h, and especially, the obtained Zn-air batteries exhibit a low discharge-charge voltage gap (1.09 V at 50 mA cm(-2)) and long cycle life (up to 408 cycles). Furthermore, the perfect bendable and twistable and rechargeable properties of the flexible Zn-air battery particularly make it a potentially power portable and wearable electronic device. PMID:27463122

  20. Bifunctional redox flow battery

    International Nuclear Information System (INIS)

    A new bifunctional redox flow battery (BRFB) system, V(III)/V(II)-L-cystine(O2), was systematically investigated by using different separators. It is shown that during charge, water transfer is significantly restricted with increasing the concentration of HBr when the Nafion 115 cation exchange membrane is employed. The same result can be obtained when the gas diffusion layer (GDL) hot-pressed separator is used. The organic electro-synthesis is directly correlated with the crossover of vanadium. When employing the anion exchange membrane, the electro-synthesis efficiency is over 96% due to a minimal crossover of vanadium. When the GDL hot-pressed separator is applied, the crossover of vanadium and water transfer are noticeably prevented and the electro-synthesis efficiency of over 99% is obtained. Those impurities such as vanadium ions and bromine can be eliminated through the purification of organic electro-synthesized products. The purified product is identified to be L-cysteic acid by IR spectrum. The BRFB shows a favorable discharge performance at a current density of 20 mA cm-2. Best discharge performance is achieved by using the GDL hot-pressed separator. The coulombic efficiency of 87% and energy efficiency of about 58% can be obtained. The cause of major energy losses is mainly associated with the cross-contamination of anodic and cathodic active electrolytes

  1. Bifunctional electrocatalyst for oxygen/air electrodes

    International Nuclear Information System (INIS)

    Highlights: • Nano-Silver powder was prepared by chemical method. • Ag catalyst was characterized by SEM and XRD studies. • Ag was investigated as bi-functional electrocatalyst for oxygen/air electrodes. • Ag shows good electrochemical activity towards OER and ORR reactions. - Abstract: Nano-Silver powder has been studied as bi-functional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline medium. Ag nano-powder has been prepared by a simple wet chemical method with Silver nitrate as precursor and Glucose as reducing agent. X-ray Diffraction and Scanning Electron Microscopy studies were carried out to characterize the Silver catalyst. Electrochemical oxygen evolution characterization shows anodic peak typically at the range between 0.350 and 0.514 V Vs Hg/HgO corresponding to Silver oxidation followed by the onset of oxygen evolution at 0.706 V. Oxygen reduction reaction studies carried out using Rotating Disc Electrode (RDE) confirm the four electron reaction mechanism. Ag catalyst shows promising characteristics for oxygen evolution and oxygen reduction

  2. Improvement of Water Sensitivity of Macro-defect-free Cement Based Composites with Cross Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The enhancement of interface bonding between cement and polymer and the structural reticulation of the water-soluble polymer are proposed to minimize the shortening of the mechanical properties of macro-defect-free (MDF) cement based composites at high relative humidity. The MDF composites incorporated with various cross-coupling agents were studied experimentally. The results show that the MDF composites modified with small amounts of cross-coupling agent had raised mechanical properties, but it is more important that the modified MDF composites had a significant increase in water resistance compared to the original one. In the meantime if the water resistant material such as fine powder of α-alumina was used to substitute for the unreacted cement grains in the MDF composites, a more efficient improvement of water resistance would be obtained. The loss in flexural strength of the MDF composites after 90 days of water immersion decreased from 62% before unmodified to 15% after modified.

  3. Creation of crosslinkable interphases in polymer blends by means of novel coupling agents

    OpenAIRE

    Sadhu, Veera Bhadraiah

    2004-01-01

    The goal of the work is to study possibilities for the modification of interface in immiscible polymer blends, which determine to a large degree of the blend properties. For this purpose novel coupling agents (named SCA) containing 2-oxazoline, 2-oxazinone, and hydrosilane reactive sites have been prepared. In blends of amino- functional and carboxylic acid terminated polymers the oxazoline and oxazinone units of the SCA react selectively with one of the polymers and, therefore, the SCA shoul...

  4. Surface modification of self-healing poly(urea-formaldehyde) microcapsules using silane-coupling agent

    International Nuclear Information System (INIS)

    Poly(urea-formaldehyde) (PUF) microcapsules, which are used as self-healing component of fibre reinforced resin matrix composites, were prepared by in situ polymerization method. The surface of PUF microcapsules was modified by using 3-aminopropyltriethoxy silane-coupling agent (KH550), and the interfacial interactions between PUF microcapsules and KH550 was also studied. Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS) analyses showed that the silane-coupling agent molecular binds strongly to PUF microcapsules surface. Chemical bond (Si-O-C) was formed by the reaction between Si-OH and the hydroxyl group of PUF microcapsules, also there have chemical adsorption effect in the interface simultaneously because of the existence of hydrogen bond between Si-OH and the hydroxyl group of PUF microcapsules. Scanning electronic microscopy (SEM) observation showed that a thin layer was formed on the surface of modified PUF microcapsules. Additionally, fractured surface were observed under SEM to investigate the interfacial adhesion effect between PUF microcapsules and epoxy matrix. The result indicted that the silane-coupling agent play an important role in improving the interfacial performance between microcapsules and resin matrix.

  5. Magnetostrictive properties of titanate coupling agent treated Terfenol-D composites

    International Nuclear Information System (INIS)

    As a kind of composites, the bond strength between the polymer matrix and the Terfenol-D particles affects the performance of magnetostrictive composites. By observing the fracture morphologies, the bond strength of the magnetostrictive composites prepared with untreated Terfenol-D was proved weak. Titanate coupling agent was used for particles to improve the bond strength. Contact angle analysis indicates the work of adhesion of the epoxy resin to the treated Terfenol-D is larger than that to the untreated Terfenol-D. Different magnetostrictive composites with 20%, 35% and 50% particle volume fractions were prepared with treated and untreated Terfenol-D particles. Their static and dynamic magnetostriction was tested without pre-stress at room temperature. The results indicate titanate coupling agent treating increases the magnetostrictive properties of magnetostrictive composites, that is probably because the bond strength improves due to the particle treating. - Highlights: ► Our experimental results indicate the particles and the polymer matrix have poor bonding. ► The poor bonding prevents the effective transfer of the strain from the particles to the matrix. ► We used titanate as the coupling agent to improve the bond strength between the particles and the matrix. ► The results indicate the bond strength does increase as expected. ► The promotion of the bond strength leads to the increase of magnetostrictive properties.

  6. ZnO nanowire-based glucose biosensors with different coupling agents

    International Nuclear Information System (INIS)

    Highlights: ► Fabrication of ZnO nanowire-based glucose biosensors using different coupling agents. ► Highest sensitivity for (3-aminopropyl)methyldiethoxysilane-treated biosensor. ► Larger amount of glucose oxidase and lower electron transfer resistance for (3-aminopropyl)methyldiethoxysilane-treated biosensor. - Abstract: ZnO-nanowire-based glucose biosensors were fabricated by immobilizing glucose oxidase (GOx) onto a linker attached to ZnO nanowires. Different coupling agents were used, namely (3-aminopropyl)trimethoxysilane (APTMS), (3-aminopropyl)triethoxysilane (APTES), and (3-aminopropyl)methyldiethoxysilane (APS), to increase the affinity of GOx binding to ZnO nanowires. The amount of GOx immobilized on the ZnO nanowires, the performance, sensitivity, and Michaelis–Menten constant of each biosensor, and the electron transfer resistance through the biosensor were all measured in order to investigate the effect of the coupling agent on the ZnO nanowire-based biosensor. Among the different biosensors, the APS-treated biosensor had the highest sensitivity (17.72 μA cm−2 mM−1) and the lowest Michaelis–Menten constant (1.37 mM). Since APS-treated ZnO nanowires showed the largest number of C-N groups and the lowest electron transfer resistance through the biosensor, we concluded that these properties were the key factors in the performance of APS-treated glucose biosensors.

  7. ZnO nanowire-based glucose biosensors with different coupling agents

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Juneui [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Lim, Sangwoo, E-mail: swlim@yonsei.ac.kr [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Fabrication of ZnO nanowire-based glucose biosensors using different coupling agents. Black-Right-Pointing-Pointer Highest sensitivity for (3-aminopropyl)methyldiethoxysilane-treated biosensor. Black-Right-Pointing-Pointer Larger amount of glucose oxidase and lower electron transfer resistance for (3-aminopropyl)methyldiethoxysilane-treated biosensor. - Abstract: ZnO-nanowire-based glucose biosensors were fabricated by immobilizing glucose oxidase (GOx) onto a linker attached to ZnO nanowires. Different coupling agents were used, namely (3-aminopropyl)trimethoxysilane (APTMS), (3-aminopropyl)triethoxysilane (APTES), and (3-aminopropyl)methyldiethoxysilane (APS), to increase the affinity of GOx binding to ZnO nanowires. The amount of GOx immobilized on the ZnO nanowires, the performance, sensitivity, and Michaelis-Menten constant of each biosensor, and the electron transfer resistance through the biosensor were all measured in order to investigate the effect of the coupling agent on the ZnO nanowire-based biosensor. Among the different biosensors, the APS-treated biosensor had the highest sensitivity (17.72 {mu}A cm{sup -2} mM{sup -1}) and the lowest Michaelis-Menten constant (1.37 mM). Since APS-treated ZnO nanowires showed the largest number of C-N groups and the lowest electron transfer resistance through the biosensor, we concluded that these properties were the key factors in the performance of APS-treated glucose biosensors.

  8. Long Alkyl Chain Organophosphorus Coupling Agents for in Situ Surface Functionalization by Reactive Milling

    Directory of Open Access Journals (Sweden)

    Annika Betke

    2014-08-01

    Full Text Available Innovative synthetic approaches should be simple and environmentally friendly. Here, we present the surface modification of inorganic submicrometer particles with long alkyl chain organophosphorus coupling agents without the need of a solvent, which makes the technique environmentally friendly. In addition, it is of great benefit to realize two goals in one step: size reduction and, simultaneously, surface functionalization. A top-down approach for the synthesis of metal oxide particles with in situ surface functionalization is used to modify titania with long alkyl chain organophosphorus coupling agents. A high energy planetary ball mill was used to perform reactive milling using titania as inorganic pigment and long alkyl chain organophosphorus coupling agents like dodecyl and octadecyl phosphonic acid. The final products were characterized by IR, NMR and X-ray fluorescence spectroscopy, thermal and elemental analysis as well as by X-ray powder diffraction and scanning electron microscopy. The process entailed a tribochemical phase transformation from the starting material anatase to a high-pressure modification of titania and the thermodynamically more stable rutile depending on the process parameters. Furthermore, the particles show sizes between 100 nm and 300 nm and a degree of surface coverage up to 0.8 mmol phosphonate per gram.

  9. Effect of silane coupling agent on interfacial adhesion of copper/glass fabric/epoxy composites

    International Nuclear Information System (INIS)

    The effect of silane coupling agent on the peel strength of copper/prep reg/copper composites was investigated. The composite consisted of one or two sheets of prepress covered by two copper plates. The prep reg was prepared by hand dry-lay-up technique using an epoxy resin and an electrical resistant glass fabric (e-glass style 2165). 4,4'-methylene dianiline. An aromatic amine, was used as curing agent. curing times for prep reg and composite at 120digC and 170digC were 15 min and 1 h, respectively. γ-aminopropyl trimethoxy silane was used as coupling agent. The effect of aminopropyl trimethoxy silane on the adhesion of epoxy/glass and epoxy/copper interfaces was investigated by two methods. In the first method, the surface of the glass fabric and/or the copper plates were treated by aminopropyl trimethoxy silane. In the second method, aminopropyl trimethoxy silane was directly added to epoxy resin. In addition, the effect of additional resin on the adhesion strength was also studied by the latter method

  10. Development of polypropylene/wood flour ecocomposites. Evaluation of silane as coupling agent

    Science.gov (United States)

    Bouza, R.; Barral, L.; Abad, M. J.; Montero, B.

    2010-06-01

    The effects of Pinus Sylvestris wood flour as filler in polypropylene matrix was evaluated. The mechanical properties and the morphology of different wood flour/polypropylene composites (WPC) were studied. The composites materials were prepared with several amounts of wood flour from 10 to 30% wt. Mechanical properties show that the wood flour incorporation increases the rigidity of the composites. Morphological analysis indicates that agglomerates are formed, with amounts exceeding 30% of wood flour. For the silane—treated composites, the dispersion of the filler into the polypropylene (PP) matrix improved. Shore D hardness of the composites is decreased with the addition of the coupling agent.

  11. Effect of a silane coupling agent on the mechanical properties of a microfibrillated cellulose composite.

    Science.gov (United States)

    Ifuku, Shinsuke; Yano, Hiroyuki

    2015-03-01

    Composite materials reinforced with microfibrillated cellulose (MFC) fibers were prepared and characterized in terms of their mechanical properties. The surface of the MFC fibers was treated with a silane coupling reagent having an NH2 functional group to improve fiber-matrix adhesion. Due to the unique structure of the MFC, which consists of nano-order-scale interconnected fibrils and microfibrils with greatly expanded surface area and submicron pore size compared to conventional cellulose, it was possible to enhance the effect of silane coupling agent and thereby improve the compatibility between the fibers and matrix and also the dispersibility of fibers. The Young's modulus was significantly increased to more than 70%. PMID:25575951

  12. Coupled agent-based and finite-element models for predicting scar structure following myocardial infarction.

    Science.gov (United States)

    Rouillard, Andrew D; Holmes, Jeffrey W

    2014-08-01

    Following myocardial infarction, damaged muscle is gradually replaced by collagenous scar tissue. The structural and mechanical properties of the scar are critical determinants of heart function, as well as the risk of serious post-infarction complications such as infarct rupture, infarct expansion, and progression to dilated heart failure. A number of therapeutic approaches currently under development aim to alter infarct mechanics in order to reduce complications, such as implantation of mechanical restraint devices, polymer injection, and peri-infarct pacing. Because mechanical stimuli regulate scar remodeling, the long-term consequences of therapies that alter infarct mechanics must be carefully considered. Computational models have the potential to greatly improve our ability to understand and predict how such therapies alter heart structure, mechanics, and function over time. Toward this end, we developed a straightforward method for coupling an agent-based model of scar formation to a finite-element model of tissue mechanics, creating a multi-scale model that captures the dynamic interplay between mechanical loading, scar deformation, and scar material properties. The agent-based component of the coupled model predicts how fibroblasts integrate local chemical, structural, and mechanical cues as they deposit and remodel collagen, while the finite-element component predicts local mechanics at any time point given the current collagen fiber structure and applied loads. We used the coupled model to explore the balance between increasing stiffness due to collagen deposition and increasing wall stress due to infarct thinning and left ventricular dilation during the normal time course of healing in myocardial infarcts, as well as the negative feedback between strain anisotropy and the structural anisotropy it promotes in healing scar. The coupled model reproduced the observed evolution of both collagen fiber structure and regional deformation following coronary

  13. Energy dispersive X-ray investigation of silane coupling agent modified nickel–manganese–gallium particle surfaces

    International Nuclear Information System (INIS)

    Highlights: ► Modification of surfaces of NiMnGa with silane coupling agents. ► Energy dispersive X-ray emission used for elemental analysis. ► Variable energy electron beams used for depth analysis on particles. ► Silane coupling agents promote silicon polymer attachment to NiMnGa particles. - Abstract: Nickel–manganese–gallium (NiMnGa) has been identified as a possible active material for kinetic energy harvesting. As monolithic crystals are susceptible to fracture, NiMnGa particle/polymer composites where the alloy remains the active material are proposed as an alternative. Optimum transfer of force requires good bonding between the alloy and the polymer matrix. The objectives of the current work were to develop a technique to examine the NiMnGa/polymer interface and the potential changes due to addition of silane coupling agents. To determine the presence of polymer/coupling agent at the alloy particle surface, an energy dispersive X-ray (EDX) spectrometer on a scanning electron microscope (SEM) was used. Using this method, it was possible to determine that Dow Corning® z6020 had the greatest interaction with the NiMnGa surface, although the polysiloxane had sufficient adherence without the use of coupling agents. This article demonstrates the novel use of EDX spectroscopy to indirectly investigate silane modification of metallic surfaces.

  14. The effects of corn zein protein coupling agent on mechanical properties of flax fiber reinforced composites

    Science.gov (United States)

    Whitacre, Ryan John

    In the field of renewable materials, natural fiber composites demonstrate the capacity to be a viable structural material. When normalized by density, flax fiber mechanical properties are competitive with E-glass fibers. However, the hydrophilic nature of flax fibers reduces the interfacial bond strength with polymer thermosets, limiting composite mechanical properties. Corn zein protein was selected as a natural bio-based coupling agent because of its combination of hydrophobic and hydrophilic properties. Zein was deposited on the surface of flax, which was then processed into unidirectional composite. The mechanical properties of zein treated samples where measured and compared against commonly utilized synthetic treatments sodium hydroxide and silane which incorporate harsh chemicals. Fourier transform infrared spectroscopy, chemical analysis, and scanning electron microscopy were also used to determine analyze zein treatments. Results demonstrate the environmentally friendly zein treatment successfully increased tensile strength 8%, flexural strength 17%, and shear strength 30% compared to untreated samples.

  15. The Compatibility Effect Of Coupling Agent On Rheological-Morphological Relationship Of Banana Fibre Reinforced Polypropylene

    International Nuclear Information System (INIS)

    The rheological properties of banana fibre reinforced polypropylene (PP/BF) composites at different composition were analysed using Shimadzu capillary rheometer. The effect of coupling agent concentration on the rheological properties was studied and followed by drawing a relationship of rheological-morphological properties of PP/BF composites. It was found that all composite system exhibits pseudoplasticity and incorporation of treated fibres consequents enhanced viscosity due to improved interfacial adhesion at fibre-matrix interface. However, it was observed that PP/BF composite with 2 wt% silane concentration does not yield further enhancement in the rheological properties when compared to that of 1 wt%. Composites with 1 wt% silane concentration were found to yield most promising compatibility effect with well-oriented and uniformly dispersed fibre morphology.

  16. Effects of the methyltrimethoxysilane coupling agent on phenolic and miscanthus composites containing calcium sulfite scrubber material

    Science.gov (United States)

    Jones, Sean

    The purpose of this research is to test the effects of methyltrimethoxysilane coupling agent on composite material containing calcium sulfite obtained from the Southern Illinois Power Co-operative. This scrubber material and the miscanthus plant are of interest due to their use in coal burning power plants to reduce toxic emission. When calcium sulfate is passed through coal fire gas emissions it absorbs mercury and sulfur. In these composites it is used as filler to reduce cost. Miscanthus is a source of both cellulose reinforcement and some natural resin. This plant has low care requirements, little mineral content, useful energy return, and positive environmental effects. Under investigation is whether a post-cure procedure or a silane coupling agent will positively impact the composite. Hot pressing alone may not be enough to fully cure the phenolic. It is hoped that the silane will increase the strength characteristics of the composite by enhancing adhesion between the calcium sulfite and phenolic resin. Possible effects on the miscanthus by the silane will also be tested. Phenolic is being utilized because of its recycling and biodegradable properties along with cost effectiveness in mass production. Composite mechanical performance was measured through 3-point bending to measure flexural strength and strain at breakage. A dynamic mechanical analyzer (DMA) was used to find thermomechanical properties. The post-cure was found to be effective, particularly on the final composite containing silane. When methyltrimethoxysilane was added to the miscanthus prior to fabrication, it was found to reduce flexural strength and density. However the addition of methyltrimethoxysilane to the calcium sulfite altered thermo-mechanical properties to a state more like pure phenolic, with added flexibility and thermal stability.

  17. Assessment of covalent bond formation between coupling agents and wood by FTIR spectroscopy and pull strength tests

    OpenAIRE

    Rasmussen, Jonas Stensgaard; Barsberg, Søren Talbro; Venås, Thomas Mark; Felby, Claus

    2014-01-01

    In the focus was the question whether metal alkoxide coupling agents – titanium, silane, and zirconium – form covalent bonds to wood and how they improve coating adhesion. In a previous work, a downshift of the lignin infrared (IR) band ∼1600 cm-1 was shown to be consistent with the formation of ether linkages between lignin and titanium coupling agent. In the present work, changes were found in the attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectra of lignin and wood mixed ...

  18. Biocomposites based on Argan nut shell and a polymer matrix: Effect of filler content and coupling agent.

    Science.gov (United States)

    Essabir, Hamid; Bensalah, Mohammed Ouadi; Rodrigue, Denis; Bouhfid, Rachid; Qaiss, Abou El Kacem

    2016-06-01

    This study aimed at developing a biocomposite using polypropylene (PP) as the matrix and Argan nut shell (ANS) as reinforcement. Also, styrene-(ethylene-butene)-styrene triblock copolymer grafted with maleic anhydride (SEBS-g-MA) was used as a coupling agent. The samples were prepared by using extrusion compounding followed by injection molding to determine the effect of filler and coupling agent content on the morphological, thermal, mechanical, and hygroscopic properties of the biocomposites. SEM micrographs revealed that good ANS dispersion/distribution into PP was achieved with an important reduction of fiber pull-out, micro-spaces, and voids with coupling agent addition. This led to substantial improvement intension, torsion, and water absorption reduction due to improved interfacial adhesion. Although ANS particles did not significantly modify the thermal stability of PP, the use of a coupling agent increased it. The experimental data were compared with several theoretical models such Voigt, Reuss, Hirsch, and Tsai-Pagano to characterize the interfacial adhesion quality and to determine the elastic modulus of a single ANS particle. Finally, all the results show that Argan waste to produce PP biocomposites is an interesting avenue to effectively deal with agricultural wastes and develop valuable industrial and practical applications. PMID:27083345

  19. EFFECTS OF COUPLING AGENTS ON THE RHEOLOGICAL BEHAVIOR OF KAOLIN FILLED POLYAMIDE 6

    Institute of Scientific and Technical Information of China (English)

    YU Zhongzhen; OU Yuchun; FENG Yupeng

    1993-01-01

    An experimental study was carried out to investigate the effects of coupling agents on the rheological properties of kaolin filled polyamide 6(PA6). We have investigated the state of dispersion and interfacial interaction of the filled systems, using scanning electron microscopy (SEM) and Molau test, respectively. It is found that the addition of the couplingagents to the PA6/ kaolin (20 wtpercent) significantly decreases the melt viscosity and the melt elasticity (first normal stress difference). Moreover, the states of dispersion and the polymer/filler interactions have significant influences on the rheological properties of kaolin/PA6 systems. The rheological behavior of KH550 kaolin /PA6 system is different from that of KH560 kaolin/PA6 system, although chemical reactions have taken place between the surface of KH550 kaolin (or KH560 kaolin) and PA6 matrix during melt processing. This is attributable, in part, to the differences in the state of dispersion of kaolins in PA6 matrix and, to a great extent, to the differences in the extent of chemical reactions that have taken place between the filler and polymer matrix.

  20. Multifunctional nanocomposites with different coupling agents: synthesis, luminescent and magnetic properties

    International Nuclear Information System (INIS)

    In this study, the co-precipitation method has been developed for the synthesized Fe3O4 nanoparticles which are encapsulated with SiO2/C/TiO2 via the facile and further functionalized by the deposition of Y2O3:Eu3+ phosphors. Transmission electron microscopy images revealed that the nanocomposites show a spherical morphology with size distribution around 100–250 nm, and the thickness of the coupling agents was 3–4 nm. The X-ray diffraction patterns showed that a cubic spinel structure of Fe3O4 core and a tetragonal phase of Y2O3:Eu3+ shell was obtained. The multifunctional nanocomposites showed ferrimagnetic behavior, the negligible coercivity Hc and remanence Mr at room temperature and showed unique europium fluorescence properties with strong red emission peak from the electric–dipole transition 5D0 → 7F2 of Eu3+ ions at 611 nm. Therefore, the multifunctional nanocomposites are expected to develop many potential applications in biomedical fields and magnetic photocatalyst.

  1. Coupling Agent-Based and Groundwater Modeling to Explore Demand Management Strategies for Shared Resources

    Science.gov (United States)

    Al-Amin, S.

    2015-12-01

    Municipal water demands in growing population centers in the arid southwest US are typically met through increased groundwater withdrawals. Hydro-climatic uncertainties attributed to climate change and land use conversions may also alter demands and impact the replenishment of groundwater supply. Groundwater aquifers are not necessarily confined within municipal and management boundaries, and multiple diverse agencies may manage a shared resource in a decentralized approach, based on individual concerns and resources. The interactions among water managers, consumers, and the environment influence the performance of local management strategies and regional groundwater resources. This research couples an agent-based modeling (ABM) framework and a groundwater model to analyze the effects of different management approaches on shared groundwater resources. The ABM captures the dynamic interactions between household-level consumers and policy makers to simulate water demands under climate change and population growth uncertainties. The groundwater model is used to analyze the relative effects of management approaches on reducing demands and replenishing groundwater resources. The framework is applied for municipalities located in the Verde River Basin, Arizona that withdraw groundwater from the Verde Formation-Basin Fill-Carbonate aquifer system. Insights gained through this simulation study can be used to guide groundwater policy-making under changing hydro-climatic scenarios for a long-term planning horizon.

  2. Socio-Ecohydrologic Agents And Services: Integrating Human And Natural Components To Address Coupled System Resilience

    Science.gov (United States)

    Pavao-zuckerman, M.; Pope, A.; Chan, D.; Curl, K.; Gimblett, H. R.; Hough, M.; House-Peters, L.; Lee, R.; Scott, C. A.

    2012-12-01

    decision-making on spatially-explicit landscapes in a mechanistic way, taking into account social interaction, adaptation, and decision-making at different levels, allowing individual stakeholders to make decisions based on their unique perceptions of their environment, be it economic, social, or ecological awareness. Initial parameterization of the ABM proceeds from a case study centered in the town of Rayón, Sonora, Mexico, where semi-structured interviews were used to elicit perceptions by water resource users of CNH function, change, and solutions relating to livelihood changes in response to several drivers. In both case studies, we see the potential and limitations for an approach to adaptive management and decision support related to water resources that links ecosystem services and agent-based modeling. Methodologically, synthetic approaches such as these may allow coupling of systems for improved assessment and analysis, while at the same time lack a connection to the perspectives of water users and managers on the ground. There is thus potential for a either a loss of system resilience in the face of external change, or an opportunity to increase system resilience by building off perspectives already in place within these coupled socio-ecohydrologic systems.

  3. Influence of silane coupling agents on the rheological behavior of hemp fiber filled polyamide 1010 biomass composites in molten state

    Science.gov (United States)

    Nishitani, Yosuke; Hasumi, Megumi; Kitano, Takeshi

    2015-05-01

    In order to develop the new engineering materials such as structural materials and tribomaterials based on all plants-derived materials, the influence of silane coupling agent on the rheological properties of hemp fiber (HF) filled polyamide 1010 (PA1010) biomass composites in molten state was investigated for one step of the fabrication of these materials. PA1010 was made from sebacic acid and decamethylenediamine, which are obtained from plant-derived castor oil. Hemp fibers were surface-treated by two types of surface treatment: a) alkali treatment by NaOH solution and b) surface treatment by silane coupling agents with different concentrations. Three types of silane coupling agents: aminosilane, epoxysilane and ureidosilane were used for surface treatment. HF/PA1010 composites were extruded by a twin screw extruder and compression-molded. Rheological behavior in molten state were evaluated by oscillatory flow testing using a parallel plate type rheometer. It was found that the silane coupling agents remarkably influence on: 1) rheological properties such as storage modulus, loss modulus, loss tangent and complex viscosity in low angular frequency region in molten state, 2) temperature dependences of rheological properties, and 3) relationship between phase angle and complex modulus (van Gurp - Palmen plots). These rheological behavior were also strongly influenced by the type of silane coupling agents. The viscoelastic properties (both storage and loss moduli) of aminosilane and epoxysilane treated composites were lower, however, those of ureidosilane treated ones were higher than the moduli of only alkali treated composites. Ureidosilane treated composites were the least temperature sensitive in the surface treated composites investigated here.

  4. Necessary and Sufficient Conditions for Circle Formations of Mobile Agents with Coupling Delay via Sampled-Data Control

    Directory of Open Access Journals (Sweden)

    Jianwei Zhao

    2016-01-01

    Full Text Available A circle forming problem for a group of mobile agents governed by first-order system is investigated, where each agent can only sense the relative angular positions of its neighboring two agents with time delay and move on the one-dimensional space of a given circle. To solve this problem, a novel decentralized sampled-data control law is proposed. By combining algebraic graph theory with control theory, some necessary and sufficient conditions are established to guarantee that all the mobile agents form a pregiven circle formation asymptotically. Moreover, the ranges of the sampling period and the coupling delay are determined, respectively. Finally, the theoretical results are demonstrated by numerical simulations.

  5. The Effect of Silane Coupling Agents on a Composite Polyamide-6/Talc

    Directory of Open Access Journals (Sweden)

    H. Wiebeck

    1998-12-01

    Full Text Available This paper evaluates the effect of the addition of silane agents on the mechanical properties (tensile strength, hardness and flexibility of the composite polyamide-6/talc. For this purpose, 30% and 40% of a talc with and without the addition of silane agents were incorporated into polyamide-6. Three kinds of silane agents were used, resulting in nine formulations. Comparing the experimental results, it is concluded that the silane agents improve the mechanical properties of the composite material.

  6. The Effect of Silane Coupling Agents on a Composite Polyamide-6/Talc

    OpenAIRE

    H. Wiebeck; D.F. Borrelly; Xavier, C; P. S. Santos; S.A. Asciutti; Corrêa, M. P.

    1998-01-01

    This paper evaluates the effect of the addition of silane agents on the mechanical properties (tensile strength, hardness and flexibility) of the composite polyamide-6/talc. For this purpose, 30% and 40% of a talc with and without the addition of silane agents were incorporated into polyamide-6. Three kinds of silane agents were used, resulting in nine formulations. Comparing the experimental results, it is concluded that the silane agents improve the mechanical properties of the composite ma...

  7. CO2 as Both a Selective Agent and Reaction Media in Palladium-Catalyzed Reductive Ullmann-Type Coupling Reaction

    Institute of Scientific and Technical Information of China (English)

    LI Jin-Heng李金恒; XIE Ye-Xiang谢叶香

    2004-01-01

    Carbon dioxide as both a selective agent and reaction media in the palladium-catalyzed Ullmann-type coupling has been described. The results showed that aryl chlorides could be easily activated in the presence of carbon dioxide and the chemoselectivity shifted toward the palladium-catalyzed Ullmann-type coupling reaction. In liquid carbon dioxide, homocoupling reactions of aryl halides, including less reactive aryl chlorides, were carried out smoothly in moderate to good yields using Pd/C, zinc, and H2O as the catalytic system at room temperature.

  8. Superhydrophobic cotton fabric coating based on a complex layer of silica nanoparticles and perfluorooctylated quaternary ammonium silane coupling agent

    Science.gov (United States)

    Yu, Minghua; Gu, Guotuan; Meng, Wei-Dong; Qing, Feng-Ling

    2007-01-01

    A superhydrophobic complex coating for cotton fabrics based on silica nanoparticles and perfluorooctylated quaternary ammonium silane coupling agent (PFSC) was reported in this article. The complex thin film was prepared through a sol-gel process using cotton fabrics as a substrate. Silica nanoparticles in the coating made the textile surface much rougher, and perfluorooctylated quaternary ammonium silane coupling agent on the top layer of the surface lowered the surface free energy. Textiles coated with this coating showed excellent water repellent property, and water contact angle (CA) increased from 133° on cotton fabrics treated with pure PFSC without silica sol pretreatment up to 145°. The oil repellency was also improved and the contact angle of CH 2I 2 droplet on the fabric surface reached to 131°. In contrast, the contact angle of CH 2I 2 on the fabric surface treated with pure PFSC was only 125°.

  9. Surface modification of TiO2 nanoparticles via photocataliticaly induced reaction: Influence of functionality of silane coupling agent

    International Nuclear Information System (INIS)

    Highlights: ► TiO2 nanoparticles were modified by photocatalytic induced surface reaction. ► TiO2 nanoparticles were subjects of modification and catalysts for the reaction. ► No cleavage of Si-C bond in silane coupling agent 3-triethoxysilyl propyl isocianate. ► High influence of functional group in silane on the Si-C cleavage was determined. ► Different electronegativity of the functionalities in the silane determines reaction way. - Abstract: In the present work the surface modification of TiO2 nanoparticles by photocatalyticaly induced reaction with silane coupling agent 3-triethoxysilyl propyl isocianate (PIC) has been presented. It was demonstrated establishing of covalent Ti-O-Si bond between the nanoparticles and the PIC molecule. In comparison with previous results, it was demonstrated the high influence of the functional group from the silane coupling agent on the reaction course during surface functionalziation of TiO2 nanoparticles. Depending on the amount and type (electronegativity of the end-functionalities) of the silane compound, high control of the surface characteristics of TiO2 nanoparticles could be achieved.

  10. Influence of additional coupling agent on the mechanical properties of polyester-agave cantala roxb based composites

    Science.gov (United States)

    Ubaidillah, Raharjo, Wijang W.; Wibowo, A.; Harjana, Mazlan, S. A.

    2016-03-01

    The mechanical and morphological properties of the unsaturated polyester resins (UPRs)-agave cantala roxb based composite are investigated in this paper. The cantala fiber woven in 3D angle interlock was utilized as the composite reinforcement. Surface grafting of the cantala fiber through chemical treatment was performed by introducing silane coupling agent to improving the compatibility with the polymer matrix. The fabrication of the composite specimens was conducted using vacuum bagging technique. The effect of additional coupling agent to the morphological appearance of surface fracture was observed using scanning electron microscopy. Meanwhile, the influence of additional silane to the mechanical properties was examined using tensile, bending and impact test. The photograph of surface fracture on the treated specimens showed the residual matrix left on the fibers in which the phenomenon was not found in the untreated specimens. Based on mechanical tests, the treated specimens were successfully increased their mechanical properties by 55%, 9.67%, and 92.4% for tensile strength, flexural strength, and impact strength, respectively, at 1.5% silane coupling agent.

  11. Influence of coupling agent content on the properties of high density polyethylene composites reinforced with oil palm fibers

    International Nuclear Information System (INIS)

    Highlights: • Palm oil fibers have been used as reinforcement in polyethylene matrix. • The coupling agent (MAPP) has been used to improve matrix-particles adhesion. • The effect of coupling agent on the morphological and mechanical properties has been studied. - Abstract: Oil palm fiber reinforced high density polyethylene (HDPE) composites which can be used in several applications (mechanical part, fiber panel, etc.) were manufactured by twin-screw extrusion followed by compression molding. In particular, the effect of coupling agent (maleated polypropylene, MAPP) concentration (0, 2, 4 and 6 wt.%) was investigated for 30 and 40 wt.% oil palm fiber. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), dynamic mechanical thermal analysis (DMTA) and mechanical testing (tension and impact) were carried out to determine the effect of fiber and compatibilizer contents. The results showed that compatibilized composites have increased stiffness due to enhanced interfacial adhesion between the fibers and the matrix, as well as better homogeneity (better fiber dispersion) due to chemical bonding. The optimum MAPP content was found to be 4% for the range of conditions tested

  12. A new bifunctional hybrid nanostructure as an active platform for photothermal therapy and MR imaging

    OpenAIRE

    Mona Khafaji; Manouchehr Vossoughi; M. Reza Hormozi-Nezhad; Rassoul Dinarvand; Felix Börrnert; Azam Irajizad

    2016-01-01

    As a bi-functional cancer treatment agent, a new hybrid nanostructure is presented which can be used for photothermal therapy by exposure to one order of magnitude lower laser powers compared to similar nanostructures in addition to substantial enhancment in magnetic resonance imaging (MRI) contrast. This gold-iron oxide hybrid nanostructure (GIHN) is synthesized by a cost-effective and high yield water-based approach. The GIHN is sheilded by PEG. Therefore, it shows high hemo and biocompatib...

  13. How coupling agent ordering on the surface of zirconia nanocrystals influences their agglomeration

    International Nuclear Information System (INIS)

    Full text: The ordering of dodecyl chains has been investigated in mixed monolayers of phosphonic acid capping agents on the surface of hydrothermal prepared zirconia nanocrystals. As co-capping agent for the mixed monolayer formation, methyl-, phenyl-, pyryl- and tert-butyl phosphonic acid have been used to investigate series with different mixing ratios. In this study, the influence of the various molecules on the alkyl chain disordering is discussed. Small angle X-ray scattering (SAXS) studies show that with increasing amount of co-capping agent the agglomeration of the particles decreases. This behavior correlates with the ordering of the surface bond alkyl chains investigated by Fourier transform infrared spectroscopy (FTIR). It can be concluded that interparticle bilayers, formed via long alkyl chain packing, are responsible for the formation of dense particle agglomerates and can be controlled on a molecular level by co-adsorbing various molecules. (author)

  14. Mechanical and dynamic characteristics of encapsulated microbubbles coupled by magnetic nanoparticles as multifunctional imaging and drug delivery agents

    Science.gov (United States)

    Guo, Gepu; Lu, Lu; Yin, Leilei; Tu, Juan; Guo, Xiasheng; Wu, Junru; Xu, Di; Zhang, Dong

    2014-11-01

    Development of magnetic encapsulated microbubble agents that can integrate multiple diagnostic and therapeutic functions is a key focus in both biomedical engineering and nanotechnology and one which will have far-reaching impact on medical diagnosis and therapies. However, properly designing multifunctional agents that can satisfy particular diagnostic/therapeutic requirements has been recognized as rather challenging, because there is a lack of comprehensive understanding of how the integration of magnetic nanoparticles to microbubble encapsulating shells affects their mechanical properties and dynamic performance in ultrasound imaging and drug delivery. Here, a multifunctional imaging contrast and in-situ gene/drug delivery agent was synthesized by coupling super paramagnetic iron oxide nanoparticles (SPIOs) into albumin-shelled microbubbles. Systematical studies were performed to investigate the SPIO-concentration-dependence of microbubble mechanical properties, acoustic scattering response, inertial cavitation activity and ultrasound-facilitated gene transfection effect. These demonstrated that, with the increasing SPIO concentration, the microbubble mean diameter and shell stiffness increased and ultrasound scattering response and inertial cavitation activity could be significantly enhanced. However, an optimized ultrasound-facilitated vascular endothelial growth factor transfection outcome would be achieved by adopting magnetic albumin-shelled microbubbles with an appropriate SPIO concentration of 114.7 µg ml-1. The current results would provide helpful guidance for future development of multifunctional agents and further optimization of their diagnostic/therapeutic performance in clinic.

  15. Mechanical and dynamic characteristics of encapsulated microbubbles coupled by magnetic nanoparticles as multifunctional imaging and drug delivery agents

    International Nuclear Information System (INIS)

    Development of magnetic encapsulated microbubble agents that can integrate multiple diagnostic and therapeutic functions is a key focus in both biomedical engineering and nanotechnology and one which will have far-reaching impact on medical diagnosis and therapies. However, properly designing multifunctional agents that can satisfy particular diagnostic/therapeutic requirements has been recognized as rather challenging, because there is a lack of comprehensive understanding of how the integration of magnetic nanoparticles to microbubble encapsulating shells affects their mechanical properties and dynamic performance in ultrasound imaging and drug delivery. Here, a multifunctional imaging contrast and in-situ gene/drug delivery agent was synthesized by coupling super paramagnetic iron oxide nanoparticles (SPIOs) into albumin-shelled microbubbles. Systematical studies were performed to investigate the SPIO-concentration-dependence of microbubble mechanical properties, acoustic scattering response, inertial cavitation activity and ultrasound-facilitated gene transfection effect. These demonstrated that, with the increasing SPIO concentration, the microbubble mean diameter and shell stiffness increased and ultrasound scattering response and inertial cavitation activity could be significantly enhanced. However, an optimized ultrasound-facilitated vascular endothelial growth factor transfection outcome would be achieved by adopting magnetic albumin-shelled microbubbles with an appropriate SPIO concentration of 114.7 µg ml−1. The current results would provide helpful guidance for future development of multifunctional agents and further optimization of their diagnostic/therapeutic performance in clinic. (paper)

  16. Metal chelators coupled with nanoparticles as potential therapeutic agents for Alzheimer's disease

    OpenAIRE

    Liu, Gang; Men, Ping; Perry, George; Smith, Mark A.

    2009-01-01

    Alzheimer's disease (AD) is a devastating neuro-degenerative disorder characterized by the progressive and irreversible loss of memory followed by complete dementia. Despite the disease's high prevalence and great economic and social burden, an explicative etiology or viable cure is not available. Great effort has been made to better understand the disease's pathogenesis, and to develop more effective therapeutic agents. However, success is greatly hampered by the presence of the blood-brain ...

  17. Effect of coupling agent on nano-ZnO modification and antibacterial activity of ZnO/HDPE nanocomposite films

    Science.gov (United States)

    Li, Y. N.; Xu, W. M.; Zhang, G. Q.

    2015-07-01

    Commercial zinc oxide nanoparticles were modified by silane coupling agent of KH550 and KH560, respectively. The obtained nanocomposite was characterized by scanning electron microscopy (SEM), Thermogravimetric analyses (TGA) and apparent sedimentation stability (Sapp). Then, nano-ZnO/high-density polyethylene (HDPE) composite films were prepared via melt blending and a hot compression-molding process. The antibacterial testing of the films against E. coli and S. aureus was carried out via plate counting. SEM, TGA and Sapp suggest the modifier of silane changed the surface hydrophilicity and effectively broke the agglomerations of nanoparticles. Antibacterial testing results indicated the antibacterial rate of the films increased with increasing nano-ZnO content. At a low doped content of 0.2 wt%, the types of coupling agent influenced the antibacterial property with that of KH560-modified nano-ZnO/HDPE KH550-modified nano-ZnO/HDPE unmodified nano-ZnO/HDPE films. When the dosage nano-ZnO was over 0.2 wt%, the differences of antibacterial activity resulted by modification was concealed by the strong antibacterial activity with near 100% of the nano- ZnO/HDPE composite films.

  18. The Effects of Coupling Agents on the Mechanical and Thermal Properties of Eucalyptus Flour/HDPE Composite

    Directory of Open Access Journals (Sweden)

    Metanawin Siripan

    2015-01-01

    Full Text Available The aim of this research was to study the effects of the coupling agents, FusabondTM E-528 (polyethylene-grafted maleic anhydride; PE-g-MA, MA and Amino Silane (Si, on the thermal properties, and mechanical properties of Eucalyptus flour-HDPE composite. Variation of the Eucalyptus flour contents in the HDPE resulted in properties of the composite. With increasing in the contents of Eucalyptus flour in polymer matrix, the mechanical properties of the HDPE composite decreased in EU-MA series samples while they were gradually decreased in EU-Si series samples. SEM micrographs showed the fracture surface of the HDPE/Eucalyptus composite at different ratios of Eucalyptus flour. SEM micrograpgh exhibited the dispersion of EU flour in polymer matrix. The samples of both coupling agents showed an increase in interfacial adhesion, observed for the considerable decreased of gaps between the matrix and the dispersed phase. However, the EU-MA sample appeared to be more uniformly than the EU-Si sample.

  19. A high efficient method for introducing reactive amines onto carbon fiber surfaces using hexachlorocyclophosphazene as a new coupling agent

    International Nuclear Information System (INIS)

    Highlights: • An innovative chemical method for surface modification of carbon fiber was proposed. • Hexachlorocyclophosphazene was used as a new multifunctional coupling agent. • The hydroxyl on the fiber surface were consumed and converted into C-O-P bonds. • A great amount of free amines were grafted onto the carbon fiber surfaces. • The interfacial shear strength (IFSS) of carbon fiber composites increased by 71.2%. - Abstract: To improve the interfacial properties of carbon fiber (CF) reinforced composites, an innovative and simple functionalized strategy has been proposed by grafting 4,4′-oxydianiline (ODA) onto carbon fiber surface using hexachlorocyclophosphazene (HCCP) as a novel coupling agent at mild reaction conditions. The chemical composition of the CF surface was confirmed by X-ray photoelectron spectra (XPS). The surface topography and surface energy of CF were examined by atomic force microscope (AFM) and dynamic contact angle tests (DCA), respectively. The interfacial shear strength (IFSS) of CF reinforced composites was studied by microbond test. The tensile strength of CF was measured by single filament tensile test. After functionalization treatment, the grafted amine groups on the fiber surface enhanced the surface wettability of modified CF and formed strong chemical bonding between fiber and matrix, improving the interfacial adhesion strength of composites. The interfacial shear strength of modified CF reinforced composites increased by 71.2% compared with that of desized CF. The interfacial enhancement mechanism was also discussed in detail. Moreover, the modified CF almost kept the original mechanical properties after functionalization

  20. Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins

    International Nuclear Information System (INIS)

    Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of Kd values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins

  1. Overcoming Heterogeneity Effects Through Polymer-Enhanced Groundwater Remediation Techniques: Coupling Polymer Floods with Chemical Oxidants and Bio-agents

    Science.gov (United States)

    Smith, M. M.; Silva, J. A.; Munakata-Marr, J.; McCray, J. E.

    2008-12-01

    Even small heterogeneity contrasts in contaminated systems (resulting from differences in permeability or contaminant saturation) can affect the distribution of injected remediation agents by channeling fluids through high-permeability flowpaths, thus bypassing some regions and leaving contaminants uncontacted. The addition of a viscous polymer solution to the remediation agent may enhance agent delivery as a result of increased cross-flow (or "sweep efficiency") into different layers of the system, if the polymer solution remains stable in the presence of the remediation agent. Our research combines various non-toxic, food- grade polymer solutions with the remediation techniques of chemical oxidation and bio-remediation, to increase the effectiveness of treatment at sites contaminated with non-aqueous phase liquids (NAPLs). The coupling of polymer floods with oxidants may help to combat contaminant "rebound" sometimes associated with incomplete contaminant destruction in low-permeability zones. Initial compatibility testing has shown that certain robust polymer/oxidant mixtures possess stable viscosities and pose low additional oxidant demands over multi-day timescales. Transport of these solutions through natural porous media was studied in column experiments, and small two-dimensional experiments with heterogeneous layering were conducted to assess effectiveness of contaminant destruction. Limitations of these compatible polymer/oxidant combinations as well as possible experimental strategies to optimize delivery are also discussed. In addition, results of polymer/microbial screening tests reveal that polymer solutions do not inhibit the dechlorinating capabilities of a microbial consortium. Preliminary findings have also raised the possibility that certain polymers may successfully serve as electron donors in the subsurface. The implications of these results for either bioaugmentation or delivery of biostimulants are presented.

  2. An agent-based negotiation approach for balancing multiple coupled control domains

    DEFF Research Database (Denmark)

    Umair, Aisha; Clausen, Anders; Jørgensen, Bo Nørregaard

    2015-01-01

    . The proposed approach can solve negotiation problems with interdependent issues across multiple coupled control domains. We demonstrate our approach by solving a coordination problem where a Combined Heat and Power Plant must allocate electricity for three commercial greenhouses to ensure the required......Solving multi-objective multi-issue negotiation problems involving interdependent issues distributed among multiple control domains is inherent to most non-trivial cyber-physical systems. In these systems, the coordinated operation of interconnected subsystems performing autonomous control is...

  3. Design and synthesis of diamide-coupled benzophenones as potential anticancer agents.

    Science.gov (United States)

    Zabiulla; Shamanth Neralagundi, H G; Bushra Begum, A; Prabhakar, B T; Khanum, Shaukath Ara

    2016-06-10

    A series of diamide-coupled benzophenone, 2-(4-benzoyl-phenoxy)-N-{2-[2-(4-benzoyl-phenoxy)-acetylamino]-phenyl}-acetamide analogues (9a-l) were synthesized by multistep reactions and all compounds were well characterized. Among the series (9a-l), compound 9k with three methyl groups at ortho position in rings A, B, and D and bromo group at the para position in ring E was selected as a lead compound by screening through multiple cancer cell types by in-vitro cytotoxic and antiproliferative assay systems. Also, the cytotoxic nature of the compound 9k resulted the regression of the tumor growth in-vivo, which could be due to decreased vascularisation in the peritoneum lining of the mice which regress the tumor growth. The results were reconfirmed in-vivo chorioallantoic membrane model which indicates a scope of developing 9k into potent anticancer drug in near future. PMID:27027818

  4. The influence of coupling agents on mechanical property retention and long-term cytocompatibility of phosphate glass fibre reinforced PLA composites.

    Science.gov (United States)

    Hasan, M S; Ahmed, I; Parsons, A J; Walker, G S; Scotchford, C A

    2013-12-01

    Completely resorbable composites are an attractive alternative for metallic bone-fracture fixation devices. However, failure of their interfacial integrity within aqueous environments, which can lead to a rapid loss of overall mechanical properties, has been reported in the literature. In this study coupling agents were investigated for phosphate glass fibre reinforced poly(lactic acid) composites. Three coupling agents with varying wettability were employed to improve initial mechanical properties and their retention in vitro via improvement of the interfacial bond between polymer matrix and fibres. Coupling agents were grafted onto the glass fibres by dip-coating in coupling agent solution at optimised concentrations. Three-aminopropyltriethoxy silane and sorbitol ended PLA oligomer treatments improved the initial flexural properties (27% strength with APS and 17% modulus via SPLA treatment) of the composites and 3-aminopropyltriethoxy silane and hexamethylene diisocyanate (HDI) treatments also decreased the loss of flexural strength and modulus during degradation. HDI treated samples retained 57.2% and 64.7% of their initial strength and modulus, respectively compared to control where only 34% of initial strength and 52% of initial modulus was retained after 28 days of degradation in PBS solution. Initial improvements in flexural properties were associated with improved shear bond strength at the interface due to covalent bonding between the glass fibres and polymer matrix provided by the coupling agents. Delay in mechanical property loss with degradation was suggested to be due to the hydrophobicity at the interface, which could have hindered the interfacial integrity loss and consequently loss of mechanical integrity of the composites. All coupling agent treated and control composites were tested for cytocompatibility using a primary human osteoblast cell line. A comparable response to the control, in terms of cell adhesion, proliferation and differentiation

  5. On the use, characterization and performance of silane coupling agents between organic coatings and metallic or ceramic substrates

    International Nuclear Information System (INIS)

    Examples are given of the use of organofunctional silane coupling agents for promoting bonding between organic coatings and metallic or ceramic (i.e. oxide) substrates. The orientation of the silane molecules and the type of bonding with the metal oxide can be determined successfully by Time-of-Flight SIMS. Oriented films of aminosilanes are demonstrated to be unstable in air. A prerinse with an inorganic silicate is introduced as a suitable method for masking the ubiquitous carbonaceous contamination at the metal surface, thus promoting the proper orientation and covalent bonding. Some practical applications are described, such as the pretreatment of Galvalumesqbullet surfaces as a replacement of existing chromate treatments in coil coating applications. Electrochemical Impedance Spectroscopy (EIS) is shown to be a powerful tool for studying the performance of the silane treatment under a paint. copyright 1996 American Institute of Physics

  6. A Multiplex PCR-coupled Liquid Bead Array for the Simultaneous Detection of Four Biothreat Agents

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, W J; Erler, A M; Nasarabadi, S L; Skowronski, E W; McCready, P M

    2004-02-04

    We have developed a 10-plexed PCR assay coupled to a 12-plexed liquid bead array to rapidly screen environmental samples for B. anthracis, Y. pestis, F. tularensis, and B. melitensis. Highly validated species -specific primer sets were used to simultaneously amplify multiple diagnostic regions unique to each individual pathogen. Resolution of the mix of amplified products was achieved by PCR product hybridization to corresponding probe sequences, attached to unique sets of fluorescent beads. The hybridized beads were processed through a flow cytometer, which detected presence and quantity of each PCR product. The assay was optimized to allow for maximum sensitivity in a multiplexed format. A high- throughput demonstration was performed where 384 simulated environmental samples were spiked with different amounts of B. thuringensis spores and pathogen DNA. The samples were robotically processed to extract DNA and arrayed for multiplexed PCR-liquid bead detection. The assay correctly identified the presence or absence of each pathogen and collected over 3,000 individual data points within a single 8-hour shift for approximately $1.20 per sample in a 10-plexed assay.

  7. Understanding coupled natural and human systems on fire prone landscapes: integrating wildfire simulation into an agent based planning system.

    Science.gov (United States)

    Barros, Ana; Ager, Alan; Preisler, Haiganoush; Day, Michelle; Spies, Tom; Bolte, John

    2015-04-01

    Agent-based models (ABM) allow users to examine the long-term effects of agent decisions in complex systems where multiple agents and processes interact. This framework has potential application to study the dynamics of coupled natural and human systems where multiple stimuli determine trajectories over both space and time. We used Envision, a landscape based ABM, to analyze long-term wildfire dynamics in a heterogeneous, multi-owner landscape in Oregon, USA. Landscape dynamics are affected by land management policies, actors decisions, and autonomous processes such as vegetation succession, wildfire, or at a broader scale, climate change. Key questions include: 1) How are landscape dynamics influenced by policies and institutions, and 2) How do land management policies and actor decisions interact to produce intended and unintended consequences with respect to wildfire on fire-prone landscapes. Applying Envision to address these questions required the development of a wildfire module that could accurately simulate wildfires on the heterogeneous landscapes within the study area in terms of replicating historical fire size distribution, spatial distribution and fire intensity. In this paper we describe the development and testing of a mechanistic fire simulation system within Envision and application of the model on a 3.2 million fire prone landscape in central Oregon USA. The core fire spread equations use the Minimum Travel Time algorithm developed by M Finney. The model operates on a daily time step and uses a fire prediction system based on the relationship between energy release component and historical fires. Specifically, daily wildfire probabilities and sizes are generated from statistical analyses of historical fires in relation to daily ERC values. The MTT was coupled with the vegetation dynamics module in Envision to allow communication between the respective subsystem and effectively model fire effects and vegetation dynamics after a wildfire. Canopy and

  8. An experimental study on the synthesis and characterization of a coupling agent incorporated PVC-Wood composite: Effects of PVC content

    International Nuclear Information System (INIS)

    A polyvinyl chloride-wood fibre thermoplastic composite was developed by incorporating a tri-component coupling agent for enhanced interfacial adhesion. Keeping the level of the coupling agent constant (2%), the mechanical and rheological properties of the composites were studied by varying PVC (or wood) component. The results showed that the composites had poor interfacial adhesion because of the large surface area of the wood fibres where the mechanical properties decreased by increasing the wood content. Similarly, the melt flow index (MFI) values increased by increasing the PVC content. However, the Fourier-Transform Infrared (FTIR) spectrum of the composite confirmed the presence of the coupling agent along with the strong cellulosic band of woof fibre. (author)

  9. The Development Status and Application of Borate Coupling Agent%硼酸酯偶联剂的发展现状及应用前景

    Institute of Scientific and Technical Information of China (English)

    赵园; 周莉; 李玉玲; 徐新宇

    2011-01-01

    硼酸酯偶联剂是一种新型的偶联剂,和传统的偶联剂相比,它具有很多新的特点.硼酸酯偶联剂以硼原子为中心原子,可以应用于含硼无机物填料的表面改性,改善含硼无机填料和聚合物之间的相容性.硼酸酯偶联剂具有硼-氧骨架,可以和硼酸盐晶须间产生良好的物理吸附作用.在改性硼酸盐晶须方面,硼酸酯偶联剂具有较好的改性效果.近年来,国内各院校对于硼酸酯偶联剂的合成与应用已有很大进展,主要用于复合材料的制备上.主要概述了硼酸酯偶联剂现阶段的发展现状及在复合材料中的应用,并介绍了硼酸酯偶联剂的应用前景.%The borate coupling agent is a new-style coupling agent. Compared with traditional coupling agents, it has many new features. Boric acid ester coupling agent, which centers on boron atom, can be applied to surface modification of inorganic fillers containing boron and improve the compatibility of inorganic filler containing boron and polymer. It possesses the boron-oxygen skeleton,which can present great physical sorption capacity to borate whisker. In terms of modification borate whisker,boric acid ester coupling agent has a good modification effect. In recent years, domestic institutions have gained great progress in the synthesis and application of boric acid ester coupling agent, which is mainly used for the preparation of composite materials. The development status of borate coupling agent and the application in composite material at the present time is summarized. Further more, the application prospect of borate coupling agent is introduced.

  10. Gold(I) catalysts with bifunctional P, N ligands.

    Science.gov (United States)

    Wetzel, Corinna; Kunz, Peter C; Thiel, Indre; Spingler, Bernhard

    2011-08-15

    A series of phosphanes with imidazolyl substituents were prepared as hemilabile PN ligands. The corresponding gold(I) complexes were tested as bifunctional catalysts in the Markovnikov hydration of 1-octyne, as well as in the synthesis of propargylamines by the three component coupling reaction of piperidine, benzaldehyde, and phenylacetylene. While the activity in the hydration of 1-octyne was low, the complexes are potent catalysts for the three component coupling reaction. In homogeneous solution the conversions to the respective propargylamine were considerably higher than under aqueous biphasic conditions. The connectivity of the imidazolyl substituents to the phosphorus atom, their substitution pattern, as well as the number of heteroaromatic substituents have pronounced effects on the catalytic activity of the corresponding gold(I) complexes. Furthermore, formation of polymetallic species with Au(2), Au(3), and Au(4) units has been observed and the solid-state structures of the compounds [(5)(2)Au(3)Cl(2)]Cl and [(3c)(2)Au(4)Cl(2)]Cl(2) (3c = tris(2-isopropylimidazol-4(5)-yl phosphane, 5 = 2-tert-butylimidazol-4(5)-yldiphenyl phosphane) were determined. The gold(I) complexes of imidazol-2-yl phosphane ligands proved to be a novel source for bis(NHC)gold(I) complexes (NHC = N-heterocyclic carbene). PMID:21761834

  11. Extrusão de compósitos de PP com fibras curtas de coco: efeito da temperatura e agentes de acoplamento Extrusion of PP composites with short coir fibers: effect of temperature and coupling agents

    Directory of Open Access Journals (Sweden)

    Evelise F. Santos

    2010-09-01

    Full Text Available Compósitos de PP com fibras curtas de coco foram preparados em extrusora, com dois perfis de temperatura, visando avaliar o efeito compatibilizante de PP modificado com vinilalcoxisilano e com anidrido maleico. Foi verificado que os dois agentes de acoplamento melhoraram o módulo elástico, a tensão máxima e a resistência à absorção de água quando os materiais foram processados utilizando-se um perfil de temperaturas mais elevadas. A morfologia dos compósitos também ficou mais homogênea na presença dos agentes de acoplamento, especialmente naqueles processados na temperatura mais alta. Esses resultados indicam que a temperatura é uma variável fundamental no estabelecimento das interações envolvendo os processos de compatibilização.PP composites filled with coir short fibers were prepared in an extruder using two temperature profiles. The objective was to evaluate the compatibilizing effect of PP modified with vinylsilane and with maleic anhydride. Both coupling agents improved elastic modulus, tensile strength and water absorption resistance when the materials were processed at the highest temperature profile. The composite morphology was more homogeneous in the presence of the coupling agents, mainly in the composites processed at the highest temperatures. These results indicate that temperature is a key variable for the establishment of the interactions involved in the coupling processes.

  12. Effect of a silane coupling agent on the optical and the mechanical characteristics of nano diamond / acrylic resin composites

    International Nuclear Information System (INIS)

    Nano diamond (ND) is a good candidate for a filler material to fabricate transparent films. This study explores a characterization of the optical and the mechanical properties of ND dispersed polymer films. An attrition milling method was adapted to break ND aggregates, and a silane coupling agent (3-methacryloxy propyl trimethoxysilane) was used to modify the ND surfaces and stabilize the dispersion. Dipentaerylthritol hexaacrylate and pentaerythritol tetraacrylate were used in the polymer matrix, and up to 3 wt.% of ND was added to improve the mechanical properties. Fabricated composites were analyzed and tested using UV-visible spectroscopy for the optical properties and a Micro-Vickers hardness tester and ball-on-disktype friction tester for the mechanical properties. Results show that the transmittance of the ND-added composite increased with decreasing aggregate size. Through the addition of small amounts of NDs, the mechanical properties were greatly improved, the material became 3.5 times as hard, and the wear rate were greatly decreased. Possible mechanisms responsible for the enhancement of the mechanical and the optical properties are discussed.

  13. Effect of a silane coupling agent on the optical and the mechanical characteristics of nano diamond / acrylic resin composites

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Min-Gun; Chun, Yoon-Soo; Lim, Dae-Soon [Korea University, Seoul (Korea, Republic of); Kim, Jung Youl [LG Electronics Inc., Seoul (Korea, Republic of)

    2014-10-15

    Nano diamond (ND) is a good candidate for a filler material to fabricate transparent films. This study explores a characterization of the optical and the mechanical properties of ND dispersed polymer films. An attrition milling method was adapted to break ND aggregates, and a silane coupling agent (3-methacryloxy propyl trimethoxysilane) was used to modify the ND surfaces and stabilize the dispersion. Dipentaerylthritol hexaacrylate and pentaerythritol tetraacrylate were used in the polymer matrix, and up to 3 wt.% of ND was added to improve the mechanical properties. Fabricated composites were analyzed and tested using UV-visible spectroscopy for the optical properties and a Micro-Vickers hardness tester and ball-on-disktype friction tester for the mechanical properties. Results show that the transmittance of the ND-added composite increased with decreasing aggregate size. Through the addition of small amounts of NDs, the mechanical properties were greatly improved, the material became 3.5 times as hard, and the wear rate were greatly decreased. Possible mechanisms responsible for the enhancement of the mechanical and the optical properties are discussed.

  14. Effect of a silane coupling agent on the optical and the mechanical characteristics of nanodiamond/acrylic resin composites

    Science.gov (United States)

    Jeong, Min-Gun; Chun, Yoon-Soo; Lim, Dae-Soon; Kim, Jung Youl

    2014-10-01

    Nanodiamond (ND) is a good candidate for a filler material to fabricate transparent films. This study explores a characterization of the optical and the mechanical properties of ND dispersed polymer films. An attrition milling method was adapted to break ND aggregates, and a silane coupling agent (3-methacryloxypropyltrimethoxysilane) was used to modify the ND surfaces and stabilize the dispersion. Dipentaerylthritol hexaacrylate and pentaerythritol tetraacrylate were used in the polymer matrix, and up to 3 wt.% of ND was added to improve the mechanical properties. Fabricated composites were analyzed and tested using UV-visible spectroscopy for the optical properties and a Micro-Vickers hardness tester and ball-on-disktype friction tester for the mechanical properties. Results show that the transmittance of the ND-added composite increased with decreasing aggregate size. Through the addition of small amounts of NDs, the mechanical properties were greatly improved, the material became 3.5 times as hard, and the wear rate were greatly decreased. Possible mechanisms responsible for the enhancement of the mechanical and the optical properties are discussed.

  15. Magnetic-plasmonic bifunctional CoO–Ag heterostructure nanoparticles

    International Nuclear Information System (INIS)

    We demonstrate the synthesis of CoO–Ag heterostructure nanoparticles by chemical reduction of AgNO3 in the presence of Co nanoparticles in oleylamine (OAm). OAm plays multiple roles as a surfactant, solvent, and reducing agent. The mechanism of surface-activated heterogeneous nucleation and growth on the preformed seeds has been proposed. At the same time, the Co nanoparticles are oxidized to form hollow CoO nanoparticles through the Kirkendall effect. The resulting CoO–Ag heterostructures display mushroom-like morphology, Ag nanoparticle as ‘cap’ attached on the ‘stem’ of hollow CoO nanoparticles. The size of Ag domains in the heterostructure nanoparticles can be tuned by controlling the volume of Co nanoparticles. The plasmonic absorption and the magnetization of the bifunctional nanoparticles were investigated. The combination of the hollow structure of the CoO and the surface plasmon resonances of the Ag domains may make them suitable for catalysis, drug delivery, therapy, and surface-enhanced Raman scattering. (papers)

  16. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    OpenAIRE

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan

    2015-01-01

    The ability to precisely control nanoscale features is increasingly exploited to develop and improve monofunctional catalysts1–4. Striking effects might also be expected in the case of bifunctional catalysts, which play an important role in hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel5–7. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called ‘intimacy criterion’8 has dictated the ...

  17. Nanoparticle Superlattices as Efficient Bifunctional Electrocatalysts for Water Splitting.

    Science.gov (United States)

    Li, Jun; Wang, Yongcheng; Zhou, Tong; Zhang, Hui; Sun, Xuhui; Tang, Jing; Zhang, Lijuan; Al-Enizi, Abdullah M; Yang, Zhongqin; Zheng, Gengfeng

    2015-11-18

    The solar-driven water splitting process is highly attractive for alternative energy utilization, while developing efficient, earth-abundant, bifunctional catalysts for both oxygen evolution reaction and hydrogen evolution reaction has remained as a major challenge. Herein, we develop an ordered CoMnO@CN superlattice structure as an efficient bifunctional water-splitting electrocatalyst, in which uniform Co-Mn oxide (CoMnO) nanoparticles are coated with a thin, continuous nitrogen-doped carbon (CN) framework. The CoMnO nanoparticles enable optimized OER activity with effective electronic structure configuration, and the CN framework serves as an excellent HER catalyst. Importantly, the ordered superlattice structure is beneficial for enhanced reactive sites, efficient charge transfer, and structural stability. This bifunctional superlattice catalyst manifests optimized current densities and electrochemical stability in overall water splitting, outperforming most of the previously reported single- or bifunctional electrocatalysts. Combining with a silicon photovoltaic cell, this CoMnO@CN superlattice bifunctional catalyst enables unassisted solar water splitting continuously for ∼5 days with a solar-to-hydrogen conversion efficiency of ∼8.0%. Our discovery suggests that these transition metal oxide-based superlattices may serve as a unique structure modality for efficient bifunctional water splitting electrocatalysts with scale-up potentials. PMID:26496655

  18. Preparation of polymer nanocomposite materials based on unsaturated polyester resin and nanosilica A200. Part II - Structural and properties of polymer nanocomposite materials based on unsaturated polyester resin and nanosilica A200 with coupling agent

    International Nuclear Information System (INIS)

    Effects of coupling agent on the structures and properties of nanocomposite materials based on unsaturated polyester resin and A200 silica nanoparticles were investigated. The viscosity of the resin/A200 silica mixtures increased with increasing coupling agent content because of forming core-shell structures and the mechanical properties of polymer nanocomposites generally were better than those without coupling agent and appeared a maximum in mechanical properties at 4.0 wt% coupling agent content. IR analyze indicated that the coupling agent had reacted with unsaturated polyester resin and A200 silica nanoparticles. SEM, Fe-SEM and TG-SDC demonstrated more homogeneous dispersion of A200 silica nanoparticles in the polymer matrix and accompanied by lower glass transition temperature and melt temperature. Furthermore, it was also found that the best dispersion route involved a methanol dispersion technique. (author)

  19. Self-organization of Au–CdSe hybrid nanoflowers at different length scales via bi-functional diamine linkers

    International Nuclear Information System (INIS)

    This work introduces a series of molecular bridging bi-functional linkers to produce laterally self-assembled nanostructures of the Au–CdSe nanoflowers on different length scales ranging from 10 nm to 100 microns. Assembly of Au nanocrystals within amorphous CdSe rods is found in the early stages of the growth of the Au–CdSe nanoflowers. The Au–CdSe nanoflowers are formed through a one-pot low temperature (150 °C) process where CdSe clusters are adsorbed on the surface of the Au cores, and they then start to form multiple arms and branches resulting in flower-shaped hybrid nanostructures. More complex assembly at a micron length scale can be achieved by means of bi-functional capping agents with appropriate alkyl chain lengths, such as 1,12-diaminododecane.

  20. Self-organization of Au–CdSe hybrid nanoflowers at different length scales via bi-functional diamine linkers

    Energy Technology Data Exchange (ETDEWEB)

    AbouZeid, Khaled Mohamed [Virginia Commonwealth University, Department of Chemistry (United States); Mohamed, Mona Bakr [Cairo University, National Institute of Laser Enhanced Science (NILES) (Egypt); El-Shall, M. Samy, E-mail: mselshal@vcu.edu [Virginia Commonwealth University, Department of Chemistry (United States)

    2016-01-15

    This work introduces a series of molecular bridging bi-functional linkers to produce laterally self-assembled nanostructures of the Au–CdSe nanoflowers on different length scales ranging from 10 nm to 100 microns. Assembly of Au nanocrystals within amorphous CdSe rods is found in the early stages of the growth of the Au–CdSe nanoflowers. The Au–CdSe nanoflowers are formed through a one-pot low temperature (150 °C) process where CdSe clusters are adsorbed on the surface of the Au cores, and they then start to form multiple arms and branches resulting in flower-shaped hybrid nanostructures. More complex assembly at a micron length scale can be achieved by means of bi-functional capping agents with appropriate alkyl chain lengths, such as 1,12-diaminododecane.

  1. Effect of properties of carbon fiber surface modified by anodic treatment and a coupling agent on electron beam cured epoxy composites

    International Nuclear Information System (INIS)

    A double modification method of carbon fiber surface physical and chemical properties was presented by which the carbon fibers were electrochemically oxidized and subsequently coated with an electron beam compatible coupling agent. The treated and untreated carbon fiber surface chemical properties and morphology were analyzed using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). And the carbon fiber surface energy was calculated through Kaelble method using contract angle measurement. The results show that the roughness and reactive groups of carbon fiber surface increase after anodic oxidization, moreover, polar composition of surface energy increase obviously. During EB curing the nitrogen-containing groups and basic species chemisorbed by carbon fiber surface restrain the initiators in the interface of composites, resulting in the weaker adhesion between the carbon fiber and the matrix. The coupling agent, acting as chemical bridge between the carbon fibers and the matrix, improves the interfacial properties of EB cured composites

  2. Synthesis and Characterization of Styrene- Ethylene-Propylene-Styrene (SEPS Grafted with Maleic Anhydride (MAH for Use as Coupling Agent in Wood Polymer Composite

    Directory of Open Access Journals (Sweden)

    M. Acevedo-Morantes

    2015-10-01

    Full Text Available Styrene-Ethylene-Propylene-Styrene (SEPS block copolymer was grafted with maleic anhydride (MAH by reactive extrusion (SEPS-g-MAH using an organic peroxide as initiator in the grafting. SEPS-g-MAH was synthesized for use as coupling agent in wood polymer composite (WPC. Identification of this compatibilizer was made using Fourier transform infrared spectroscopy (FTIR and the grafting degree was determinate with titration. The characteristic peaks in FTIR analysis indicated the presence of MAH in the copolymer.

  3. Synthesis and Characterization of Styrene- Ethylene-Propylene-Styrene (SEPS) Grafted with Maleic Anhydride (MAH) for Use as Coupling Agent in Wood Polymer Composite

    OpenAIRE

    M. Acevedo-Morantes; Tapia, A.; Correa, J. (José); A. Realpe-Jimenez; C. Gartner

    2015-01-01

    Styrene-Ethylene-Propylene-Styrene (SEPS) block copolymer was grafted with maleic anhydride (MAH) by reactive extrusion (SEPS-g-MAH) using an organic peroxide as initiator in the grafting. SEPS-g-MAH was synthesized for use as coupling agent in wood polymer composite (WPC). Identification of this compatibilizer was made using Fourier transform infrared spectroscopy (FTIR) and the grafting degree was determinate with titration. The characteristic peaks in FTIR analysis indicated the presence o...

  4. Study of the leaching of heavy metals from waste water sludge and incinerator's ash, using coupled thermostated columns and DTPA as complex agent

    International Nuclear Information System (INIS)

    We studied the metallic composition from waste water sludge and incinerators ashes of an incinerator located in Toluca, Mexico, the qualitative studies were made using the Activation Analysis technique, and fluorescence X-ray techniques. The quantitative analysis of heavy metals in the wastes were made using Inductively coupled plasma atomic emission spectrometry (Icp-Aes). For leaching the samples, we used four coupled thermostated columns, each one had a p H of 2,5, 7 and 10. The flux of the air was of 1600 cc/min. The temperature was maintain constant in 60 Centigrade using a thermostated system. For this study we used 100 g of wastes mixed with mineral acid or sodium hydroxide to reach p H 2,5,7 and 10. We added a reducing and tensoactive agents and finally DTPA as complex agent. With this method, we obtain a better leaching efficiency using a complex agent. However the high DTPA cost, make this process expansive that is why we recommend to work with another classes of complex agents, that be cheaper to leach metals of different chemistry matrix. (Author)

  5. Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

    Energy Technology Data Exchange (ETDEWEB)

    Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

    2016-08-02

    Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

  6. Functionalization of nanoparticle titanium dioxide with different bifunctional organic molecules and trimers of transition compounds for obtaining new materials

    International Nuclear Information System (INIS)

    Functionalization of titanium dioxide in nanoporous anatase phase is investigated for obtaining new nanomaterials. Functionalizations were performed using two heating methods: the conventional of refluxing heating method and microwave irradiation with bifunctional organic molecules is used to study how to anchor molecules and the change in the wettability of the material. Besides, reactions with organic molecules were performed as the derived from nanoproxene. The growth layer by layer is performed using the bifunctional molecules previous for the immobilization of cobalt trimers. Functionalized molecules were characterized by infrared spectroscopy, X-ray diffraction, contact angle, scanning electron microscopy, x-ray elemental analysis, plasma atomic emission spectroscopy coupled inductively, x-ray photoelectron spectroscopy and thermogravimetric analysis. This type of functionalizations on nanoporous titanium dioxide could potentially improve optical sensitivity and activity of this nanomaterial in the visible region. (author)

  7. A Novel Application of Agent-based Modeling: Projecting Water Access and Availability Using a Coupled Hydrologic Agent-based Model in the Nzoia Basin, Kenya

    Science.gov (United States)

    Le, A.; Pricope, N. G.

    2015-12-01

    Projections indicate that increasing population density, food production, and urbanization in conjunction with changing climate conditions will place stress on water resource availability. As a result, a holistic understanding of current and future water resource distribution is necessary for creating strategies to identify the most sustainable means of accessing this resource. Currently, most water resource management strategies rely on the application of global climate predictions to physically based hydrologic models to understand potential changes in water availability. However, the need to focus on understanding community-level social behaviors that determine individual water usage is becoming increasingly evident, as predictions derived only from hydrologic models cannot accurately represent the coevolution of basin hydrology and human water and land usage. Models that are better equipped to represent the complexity and heterogeneity of human systems and satellite-derived products in place of or in conjunction with historic data significantly improve preexisting hydrologic model accuracy and application outcomes. We used a novel agent-based sociotechnical model that combines the Soil and Water Assessment Tool (SWAT) and Agent Analyst and applied it in the Nzoia Basin, an area in western Kenya that is becoming rapidly urbanized and industrialized. Informed by a combination of satellite-derived products and over 150 household surveys, the combined sociotechnical model provided unique insight into how populations self-organize and make decisions based on water availability. In addition, the model depicted how population organization and current management alter water availability currently and in the future.

  8. Enhanced heat transfer through filler-polymer interface by surface-coupling agent in heat-dissipation material: A non-equilibrium molecular dynamics study

    International Nuclear Information System (INIS)

    Developing a composite material of polymers and micrometer-sized fillers with higher heat conductance is crucial to realize modular packaging of electronic components at higher densities. Enhancement mechanisms of the heat conductance of the polymer-filler interfaces by adding the surface-coupling agent in such a polymer composite material are investigated through the non-equilibrium molecular dynamics (MD) simulation. A simulation system is composed of α-alumina as the filler, bisphenol-A epoxy molecules as the polymers, and model molecules for the surface-coupling agent. The inter-atomic potential between the α-alumina and surface-coupling molecule, which is essential in the present MD simulation, is constructed to reproduce the calculated energies with the electronic density-functional theory. Through the non-equilibrium MD simulation runs, we find that the thermal resistance at the interface decreases significantly by increasing either number or lengths of the surface-coupling molecules and that the effective thermal conductivity of the system approaches to the theoretical value corresponding to zero thermal-resistance at the interface. Detailed analyses about the atomic configurations and local temperatures around the interface are performed to identify heat-transfer routes through the interface

  9. Study on the uptake and distribution of gadolinium based contrast agents in biological samples using laser ablation with inductively coupled plasma mass spectroscopy

    International Nuclear Information System (INIS)

    Gadolinium based contrast agents are used for magnetic resonance imaging. After their excretion by medicated patients they reach surface water passing waste water treatment plants where they are not removed sufficiently. The behavior of the contrast agents in the environment and the interaction with organisms was investigated in this work due to the toxicity of the free Gd3+ ion and the associated risks, such as accumulation in the human food chain. In this work, the two elemental analytical imaging methods laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and synchrotron radiation X-ray fluorescence analysis (SRXRF) have been used to investigate the uptake, distribution, and excretion of Gd-based contrast agents by various biological systems. Both methods were analytically characterized and compared for this application. The detection limits of gadolinium were determined under optimized conditions by LA-ICP-MS and SRXRF. With calibration by remains of dried elemental standard droplets detection limits of 0.78 pg absolute amount of gadolinium (LA-ICP-MS), respectively 89 pg (SRXRF) were reached. Based on filamentous algae as water plants the uptake and the excretion of Gd-based contrast agents were revealed. The dependence on concentration of the contrast agent in the exposition solution and the independence of temporal uptake within one to seven days were studied for duckweed. By LA-ICP-MS gadolinium was quantified in a leaf of cress plant. The verification of the results was performed by SRXRF and ICP-MS after digestion. Furthermore, the uptake and distribution of Gd-based contrast agents in higher organisms (water flea) were observed. The exact location of gadolinium was resolved by three-dimensional μ-computed tomography by the comparison of an exposed with a Gd-free water flea. In all studies, gadolinium was detected in the investigated exposed model organisms. It can be concluded that the contrast agents were taken from the environment.

  10. The Effect Of Coupling Agent On Composite Magnet Characteristic Based On Hexa ferrite (Sr M/Ba M) With Polyester And Epoxy Binder

    International Nuclear Information System (INIS)

    Magnetic composites are mixtures of hexa ferrite powder and non magnetic materials such as polymers as binders. These composites have been investigated because they are light, elastic, and cheap. In this study thermoset polymer (epoxy and polyester) were used as binders. Inside study of coupling agent added effect on mechanical properties, hardness and microstructure. The composites were prepared by mixture thermoset polymer epoxy or polyester with hexa ferrite powder Sr M (SrFe12O19) or Ba M (BaFe12O19) with volume fraction of 40,50 and 60 % v/v, coupling agent of the Tetra Isopropyl Titanate in the amount of 5 ml or 10 ml are added before mix turing of the thermoset polymer epoxy or polyester with hexa ferrite powder. The resulting composite were characterized mechanically (tensile strength), hardness and microstructure test. The results showed that the tensile strength and hardness of the composite magnet were increased by increasing the composition of magnetic powder, either Sr M or Ba M, it caused by microstructure of particle Sr M magnetic powder 1.6 μm in the form splinter, where as the Ba M magnetic powder 1,2 μm in nodular form. Thermoset polymer epoxy as binder have tensile strength and hardness is bigger than composite magnet based on polyester, either Sr M or Ba M. The addition of coupling agent is very influenced on the tensile strength and hardness composite magnet, the more coupling magnet addition causes the more tensile strength and hardness of the composite magnet

  11. A Cascade-Reaction Nanoreactor Composed of a Bifunctional Molecularly Imprinted Polymer that Contains Pt Nanoparticles.

    Science.gov (United States)

    Wang, Jiao; Zhu, Maiyong; Shen, Xiaojuan; Li, Songjun

    2015-05-11

    This study was aimed at addressing the present challenge of cascade reactions, namely, how to furnish the catalysts with desired and hierarchical catalytic ability. This issue was addressed by constructing a cascade-reaction nanoreactor made of a bifunctional molecularly imprinted polymer containing acidic catalytic sites and Pt nanoparticles. The acidic catalytic sites within the imprinted polymer allowed one specified reaction, whereas the encapsulated Pt nanoparticles were responsible for another coupled reaction. To that end, the unique imprinted polymer was fabricated by using two well-coupled templates, that is, 4-nitrophenyl acetate and 4-nitrophenol. The catalytic hydrolysis of the former compound at the acidic catalytic sites led to the formation of the latter compound, which was further reduced by the encapsulated Pt nanoparticles to 4-aminophenol. Therefore, this nanoreactor demonstrated a catalytic-cascade ability. This protocol opens up the opportunity to develop functional catalysts for complicated chemical processes. PMID:25846700

  12. Evaluation of copper-labeled bifunctional chelate-albumin conjugates for blood pool imaging

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, C.J.; Rocque, P.A.; Welch, M.J. (Washington Univ., St. Louis, MO (United States). Edward Mallinckrodt Inst. of Radiology); Weinheimer, C.J. (Washington Univ., St. Louis, MO (United States). School of Medicine)

    1993-05-01

    [sup 62]Cu is a generator-produced positron-emitting radionuclide with a half-life amenable to blood-pool imaging with PET. Three bifunctional chelates [cyclic anhydride of diethylenetriamine-pentaacetic acid (cDTPAA), 6-bromoacetamidobenzyl-1,4,8,11-tetraazacyclotetradecane-N,N',N'', N''' tetraacetic acid (BAT), and p-carboxyethylphenylglyoxal-bis-([sup 4])N-methyl-thiosemicarbazone (CE-DTS)] were conjugated to HSA and labeled with [sup 67]Cu. Blood clearance and biodistribution of these three [sup 67]Cu-labeled conjugates were determined in rats. Of the three [sup 67]Cu-labeled bifunctional chelate-HSA conjugates, [sup 67]Cu-benzyl-TETA-HSA remained in the blood pool the longest, achieving stable blood levels at times longer than 24 h post-injection. The [sup 67]Cu radioactivity cleared the blood within 60 min post-injection of [sup 67]Cu-DTS-HSA, and within 10 min after administration of [sup 67]Cu-DTPA-HSA, indicating the dissociation of Cu[sup 2+] from these conjugates. Copper-labeled DTS-HSA achieved stable blood concentrations for at least 30 min post-injection and was therefore evaluated as a vascular imaging agent. DTS-HSA and benzy-TETA-HSA were labeled with [sup 62]Cu and administered to a dog for blood-pool imaging using PET. Because of the high labeling efficiency, DTS-HSA can be labeled with [sup 62]Cu without purification, making it more practical than [sup 62]Cu-benzyl-TETA-HSA as a blood-pool imaging agent. Generator-produced [sup 62]Cu-DTS-HSA should be a viable alternative blood pool agent to cyclotron-produced C[sup 15]O for PET facilities without cyclotrons. (author).

  13. Novel Bifunctional Natriuretic Peptides as Potential Therapeutics*

    Science.gov (United States)

    Dickey, Deborah M.; Burnett, John C.; Potter, Lincoln R.

    2008-01-01

    Synthetic atrial natriuretic peptide (carperitide) and B-type natriuretic peptide (BNP; nesiritide) are used to treat congestive heart failure. However, despite beneficial cardiac unloading properties, reductions in renal perfusion pressures limit their clinical effectiveness. Recently, CD-NP, a chimeric peptide composed of C-type natriuretic peptide (CNP) fused to the C-terminal tail of Dendroaspis natriuretic peptide (DNP), was shown to be more glomerular filtration rate-enhancing than BNP in dogs. However, the molecular basis for the increased responsiveness was not determined. Here, we show that the DNP tail has a striking effect on CNP, converting it from a non-agonist to a partial agonist of natriuretic peptide receptor (NPR)-A while maintaining the ability to activate NPR-B. This effect is specific for human receptors because CD-NP was only a slightly better activator of rat NPR-A due to the promiscuous nature of CNP in this species. Interesting, the DNP tail alone had no effect on any NPR even though it is effective in vivo. To further increase the potency of CD-NP for NPR-A, we converted two different triplet sequences within the CNP ring to their corresponding residues in BNP. Both variants demonstrated increased affinity and full agonist activity for NPR-A, whereas one was as potent as any NPR-A activator known. In contrast to a previous report, we found that DNP binds the natriuretic peptide clearance receptor (NPR-C). However, none of the chimeric peptides bound NPR-C with significantly higher affinity than endogenous ligands. We suggest that bifunctional chimeric peptides represent a new generation of natriuretic peptide therapeutics. PMID:18940797

  14. Novel bifunctional natriuretic peptides as potential therapeutics.

    Science.gov (United States)

    Dickey, Deborah M; Burnett, John C; Potter, Lincoln R

    2008-12-12

    Synthetic atrial natriuretic peptide (carperitide) and B-type natriuretic peptide (BNP; nesiritide) are used to treat congestive heart failure. However, despite beneficial cardiac unloading properties, reductions in renal perfusion pressures limit their clinical effectiveness. Recently, CD-NP, a chimeric peptide composed of C-type natriuretic peptide (CNP) fused to the C-terminal tail of Dendroaspis natriuretic peptide (DNP), was shown to be more glomerular filtration rate-enhancing than BNP in dogs. However, the molecular basis for the increased responsiveness was not determined. Here, we show that the DNP tail has a striking effect on CNP, converting it from a non-agonist to a partial agonist of natriuretic peptide receptor (NPR)-A while maintaining the ability to activate NPR-B. This effect is specific for human receptors because CD-NP was only a slightly better activator of rat NPR-A due to the promiscuous nature of CNP in this species. Interesting, the DNP tail alone had no effect on any NPR even though it is effective in vivo. To further increase the potency of CD-NP for NPR-A, we converted two different triplet sequences within the CNP ring to their corresponding residues in BNP. Both variants demonstrated increased affinity and full agonist activity for NPR-A, whereas one was as potent as any NPR-A activator known. In contrast to a previous report, we found that DNP binds the natriuretic peptide clearance receptor (NPR-C). However, none of the chimeric peptides bound NPR-C with significantly higher affinity than endogenous ligands. We suggest that bifunctional chimeric peptides represent a new generation of natriuretic peptide therapeutics. PMID:18940797

  15. Construction and evaluation of a novel bifunctional phenylalanine-formate dehydrogenase fusion protein for bienzyme system with cofactor regeneration.

    Science.gov (United States)

    Jiang, Wei; Fang, Bai-Shan

    2016-05-01

    Phenylalanine dehydrogenase (PheDH) plays an important role in enzymatic synthesis of L-phenylalanine for aspartame (sweetener) and detection of phenylketonuria (PKU), suggesting that it is important to obtain a PheDH with excellent characteristics. Gene fusion of PheDH and formate dehydrogenase (FDH) was constructed to form bifunctional multi-enzymes for bioconversion of L-phenylalanine coupled with coenzyme regeneration. Comparing with the PheDH monomer from Microbacterium sp., the bifunctional PheDH-FDH showed noteworthy stability under weakly acidic and alkaline conditions (pH 6.5-9.0). The bifunctional enzyme can produce 153.9 mM L-phenylalanine with remarkable performance of enantiomers choice by enzymatic conversion with high molecular conversion rate (99.87 %) in catalyzing phenylpyruvic acid to L-phenylalanine being 1.50-fold higher than that of the separate expression system. The results indicated the potential application of the PheDH and PheDH-FDH with coenzyme regeneration for phenylpyruvic acid analysis and L-phenylalanine biosynthesis in medical diagnosis and pharmaceutical field. PMID:26819086

  16. Novel One-pot Fabrication of Lab-on-a-Bubble@Ag Substrate without Coupling-agent for Surface Enhanced Raman Scattering

    OpenAIRE

    Jizhou Jiang; Lei Ou-Yang; Lihua Zhu; Jing Zou; Heqing Tang

    2014-01-01

    Through in-situ reduction of silver nitrate without using any coupling-agent, a substrate for surface-enhanced Raman scattering (SERS) was prepared by coating silver on hollow buoyant silica microspheres as a lab on a bubble (LoB). The silver coated LoBs (LoBs@Ag) floated on surface of a solution could provide a very convenient platform for the detection of target molecules in the solution. The LoBs@Ag substrate not only immobilized well-distributed Ag nanoparticles on the surface LoBs, but e...

  17. Gadolinium and fluorescent bi-functionally labeling and in vitro MRI of rat bone marrow mesenchymal stem cells

    International Nuclear Information System (INIS)

    Objective: To determine the feasibility of magnetically labeling and tracking mesenchymal stem cells (MSCs) in vitro by using a gadolinium and fluorescent bi-functionally transfection agent of polyethylenimine. Methods: A gadolinium bifunctional transfection reagent complex was obtained after the linear polyethylenimine derivative (JetPEI-FluoR) was incubated with Gd-DTPA. Mesenchymal stem cells isolated from the bone marrows of SD rats were cultured and expanded. The mesenchymal stem cells were incubated with the bi-functional labeling agents. After labeling, the MSCs were examined with fluoroscope and electron microscope and the biological characters were detected including trypan blue exclusion test, MTT, and apoptosis detection. On a 1.5 T MR system, the labeled MSCs were examined with spin echo T1WI and T2WI and T1 measurement with mixed sequence. After labeling, the cells were cultured and undergone routine passage. Prior MR examinations were repeated for each passage of labeled cells. All data was statistically prolessed with SPSS for Windows. Results: Of 5 x 105 MSCs incubated with the bi-functional agents, 4.25 x 105 MSCs were successfully labeled, the percentage of labeled MSCs was 85% fluoroscopically. The high density electron particles of gadolinium observed electron microscopically existed around cellular apparatuses, especially around Golgi apparatus. In trypan blue exclusion test, the exclusion rate of labeled MSCs with incubation duration of 3,6,12,24 h was (96.55±2.90)%, (94.17± 2.56)%, (97.16±3.12)% and (94.23±2.67)%, respectively. The corresponding exclusion rate of unlabeled MSCs was (95.86±2.67)%, (92.04±2.21)%, (93.38±3.64)% and (92.12±2.53)%, respectively. There was no statistical difference of trypan blue exclusion rate between labeled cells and control unlabeled cells within 24 hours of incubation (F=4.523, P>0.05). In the proliferation test, the optical absorption value of labeled MSC with 2.5, 5.0, 10.0, 20.0, 30.0 and 40.0

  18. Robust Control of PEP Formation Rate in the Carbon Fixation Pathway of C4 Plants by a Bi-functional Enzyme

    Directory of Open Access Journals (Sweden)

    Hart Yuval

    2011-10-01

    Full Text Available Abstract Background C4 plants such as corn and sugarcane assimilate atmospheric CO2 into biomass by means of the C4 carbon fixation pathway. We asked how PEP formation rate, a key step in the carbon fixation pathway, might work at a precise rate, regulated by light, despite fluctuations in substrate and enzyme levels constituting and regulating this process. Results We present a putative mechanism for robustness in C4 carbon fixation, involving a key enzyme in the pathway, pyruvate orthophosphate dikinase (PPDK, which is regulated by a bifunctional enzyme, Regulatory Protein (RP. The robust mechanism is based on avidity of the bifunctional enzyme RP to its multimeric substrate PPDK, and on a product-inhibition feedback loop that couples the system output to the activity of the bifunctional regulator. The model provides an explanation for several unusual biochemical characteristics of the system and predicts that the system's output, phosphoenolpyruvate (PEP formation rate, is insensitive to fluctuations in enzyme levels (PPDK and RP, substrate levels (ATP and pyruvate and the catalytic rate of PPDK, while remaining sensitive to the system's input (light levels. Conclusions The presented PPDK mechanism is a new way to achieve robustness using product inhibition as a feedback loop on a bifunctional regulatory enzyme. This mechanism exhibits robustness to protein and metabolite levels as well as to catalytic rate changes. At the same time, the output of the system remains tuned to input levels.

  19. Experimental verifications on chemical carcinogenesis, a bifunctional alkylation between DNA interstrands

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It is evidenced by the filter elution method that two carcinogenic aromatic hydrocarbons, benzo[a]pyrene and dibenzo[a,h]anthracene, two carcinogenic metal salts, beryllium chloride and cadmium chloride, four carcinogenic aromatic amines, 2-aminofluorene, β-naphthylamine, 4-aminobiphenyl and benzidine, can all induce DNA interstrand and DNA-protein cross-link in L1210 culture. However, under the same condition, the corresponding non-carcinogenic compounds, including benzo[k]fluorancene, anthracene, magnesium chloride, zinc chloride, a -naphthylamine, 2-aminobiphenyl and m-toluidine, cannot produce any cross-link adducts. All these results are consistent with the di-region theory that carcinogens are bio-bifunctional alkylation agents. This method can also be used to discriminate carcinogens and non-carcinogens.

  20. Chemical modification of multiwalled carbon nanotube with a bifunctional caged ligand for radioactive labelling

    International Nuclear Information System (INIS)

    Graphical abstract: The findings of this work describe a new method that can be utilised to radioactively label multiwalled carbon nanotube (MWCNT) powders with the use of a bi-functional cage ligand. -- Abstract: Carboxyl-functionalized multiwalled carbon nanotubes (MWCNTs) have been successfully radiolabelled with cobalt-57 (57Co) (T1/2 = 270 days) via the attachment of the bifunctional caged ligand MeAMN3S3sar. In this study MeAMN3S3sar has been synthesized and coupled to MWCNTs to form the conjugate MWCNT–MeAMN3S3sar. Synthesis was confirmed with nuclear magnetic resonance. X-ray photoelectron spectroscopy (XPS) confirmed the conjugation. Non-radioactive labelling of this conjugate was completed with Cu(II) ions to confirm the stability of the MeAMN3S3sar after coupling with the MWCNTs. The complexation of the Cu(II) was also confirmed with XPS. Transmission electron microscopy was used to demonstrate that the coupling reaction had a negligible effect on the size and shape of the MWCNTs. Radiolabelling of the MWCNT–MeAMN3S3sar conjugate and pristine (untreated) MWCNTs (non-specific) with the gamma-emitting radioactive isotope 57Co were compared. The radiolabelling efficiency of the MWCNT–MeAMN3S3sar conjugate was significantly higher (95% vs. 0.1%) (P ⩽ 0.001) than for the unconjugated pristine MWCNTs. This will allow for the potential tracking of nanoparticle movement in vitro and in vivo

  1. Bifunctional mesoporous silicas with clearly distinguished localization of grafted groups

    Science.gov (United States)

    Roik, N. V.; Belyakova, L. A.

    2013-12-01

    Bifunctional mesoporous silicas with clearly distinguished localization of grafted groups on the surface of particles and inside their pores were obtained by means of sol-gel synthesis with postsynthetic vapor-phase treatment in vacuum. It was found that the synthesized materials have the hexagonally ordered porous structure typical of MCM-41 type silica.

  2. Single flexible nanofiber to simultaneously realize electricity-magnetism bifunctionality

    International Nuclear Information System (INIS)

    In order to develop new-typed multifunctional composite nanofibers, PANI/Fe3O4/PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe3O4 nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electrical conductivity and magnetic properties. The electrical conductivity reaches up to the order of 10-3 S·cm-1. The electrical conductivity and saturation magnetization of the composite nanofibers can be respectively tuned by adding various amounts of PANI and Fe3O4 NPs. The obtained electricity-magnetism bifunctional composite nanofibers are expected to possess many potential applications in areas such as electromagnetic interference shielding, special coating, microwave absorption, molecular electronics and future nanomechanics. More importantly, the design concept and construct technique are of universal significance to fabricate other bifunctional one-dimensional nanostructures. (author)

  3. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    NARCIS (Netherlands)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-01-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts(1-4). Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon source

  4. Single flexible nanofiber to simultaneously realize electricity-magnetism bifunctionality

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ming; Sheng, Shujuan; Ma, Qianli; Lv, Nan; Yu, Wensheng; Wang, Jinxian; Dong, Xiangting; Liu, Guixia, E-mail: wenshengyu2009@sina.com, E-mail: dongxiangting888@163.com [Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun (China)

    2016-03-15

    In order to develop new-typed multifunctional composite nanofibers, PANI/Fe{sub 3}O{sub 4}/PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe{sub 3}O{sub 4} nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electrical conductivity and magnetic properties. The electrical conductivity reaches up to the order of 10{sup -3} S·cm{sup -1}. The electrical conductivity and saturation magnetization of the composite nanofibers can be respectively tuned by adding various amounts of PANI and Fe{sub 3}O{sub 4} NPs. The obtained electricity-magnetism bifunctional composite nanofibers are expected to possess many potential applications in areas such as electromagnetic interference shielding, special coating, microwave absorption, molecular electronics and future nanomechanics. More importantly, the design concept and construct technique are of universal significance to fabricate other bifunctional one-dimensional nanostructures. (author)

  5. BIODEGRADATION, MORPHOLGICAL, AND FTIR STUDY OF RATTAN POWDER-FILLED NATURAL RUBBER COMPOSITES AS A FUNCTION OF FILLER LOADING AND A SILANE COUPLING AGENT

    Directory of Open Access Journals (Sweden)

    Komethi Muniandy,

    2012-01-01

    Full Text Available Natural rubber (NR composites were prepared by the incorporation of rattan (Calamus Manan powder at filler loadings in the range of 0 to 30 phr into a natural rubber matrix with a laboratory size two roll mill. The particle size of rattan powder was less than 180 µm. The biodegradation of the rattan powder-filled natural rubber (NR composites were investigated as a function of filler loading and a silane coupling agent. A soil burial test was carried out for six months, and the degradation of the NR compound and the NR composites was evaluated through tensile testing. Morphological properties were determined using scanning electron microscopy (SEM to evaluate the degradation of the samples after six months of soil exposure. The results indicate that the tensile strength, elongation at break, and stress at 100% elongation (M 100 all decreased after soil burial testing due to the biological attack by microbes onto the sample. Improvement in tensile properties was seen with the addition of the silane coupling agent due to better adhesion between the rattan filler and the rubber matrix. The deterioration in tensile properties due to the biodegradation process was confirmed by SEM and FTIR studies.

  6. The influence of starch oxidization and aluminate coupling agent on interfacial interaction, rheological behavior, mechanical and thermal properties of poly(propylene carbonate)/starch blends

    Science.gov (United States)

    Jiang, Guo; Zhang, Shui-Dong; Huang, Han-Xiong; The Key Laboratory of Polymer Processing Engineering of the Ministry of Education Team

    Poly(propylene carbonate) (PPC) is a kind of new biodegradable polymer that is synthesized by copolymerization of propylene oxide and carbon dioxide. In this work, PPC end-capped with maleic anhydride (PPCMA)/thermoplastic starch (TPS), PPCMA/thermoplastic oxidized starch (TPOS) and PPCMA/AL-TPOS (TPOS modified by aluminate coupling agent) blends were prepared by melt blending to improve its thermal and mechanical properties. FTIR results showed that there existed hydrogen-bonding interaction between PPCMA and starch. SEM observation revealed that the compatibility between PPCMA and TPOS was improved by the oxidation of starch. The enhanced interfacial interactions between PPCMA and TPOS led to a better performance of PPC blends such as storage modulus (G'), loss modulus (G''), complex viscosity (η*), tensile strength and thermal properties. Furthermore, the modification of TPOS by aluminate coupling agent (AL) facilitated the dispersion of oxidized starch in PPC matrix, and resulted in increasing the tensile strength and thermal stability. National Natural Science Foundation of China, National Science Fund of Guangdong Province.

  7. Improving Filler Dispersion And Physical Properties Of Epoxidized Natural Rubber/ Silica Compound By Using Dual fillers And Coupling Agent In Mixing Process

    International Nuclear Information System (INIS)

    Since the introduction of Green Tyre concept, in the early 90s, the use of silica as reinforcing fillers has spread and grown worldwide. The general advantages of silica as reinforcing filler over carbon black filler are better rolling resistance by achieving at least equal wet traction while tread wear should not be adversely affected. In general, high filler loading in ENR attributes poor dispersion and lack of adhesion to the rubber matrix which in turn affect the processability and physical properties of the rubber compounds. In this work, effect of dual fillers (silica and carbon black) and coupling agent in ENR/ silica compound was studied respectively. The mixing was done in a Banbury® BR 1600 internal mixer and the filler dispersion and physical properties were analysed. The carbon black filler was varied from 5 phr to 20 phr, where the total filler was fixed at 60 phr for truck tyre tread compound. The coupling agent was mixed in the mixing at two different stages which is first stage and finalizing stage of mixing. The rheological properties test was conducted by using Mooney Viscometer. The hardness, abrasion and tensile strength for physical properties evaluation were also conducted in this study. In addition, the filler dispersion property was determined by using disperGraderTM. The results showed that some of ENR/silica compound properties such as tensile, hardness, filler dispersion and abrasion resistance were slightly improved as compared to control compound. (author)

  8. Comparison of bifunctional chelates for {sup 64}Cu antibody imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cara L.; Crisp, Sarah; Bensimon, Corinne [MDS Nordion, Vancouver, BC (Canada); Yapp, Donald T.T.; Ng, Sylvia S.W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); University of British Columba, The Faculty of Pharmaceutical Sciences, Vancouver, BC (Canada); Sutherland, Brent W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); Gleave, Martin [Prostate Centre at Vancouver General Hospital, Vancouver, BC (Canada); Jurek, Paul; Kiefer, Garry E. [Macrocyclics Inc., Dallas, TX (United States)

    2010-11-15

    Improved bifunctional chelates (BFCs) are needed to facilitate efficient {sup 64}Cu radiolabeling of monoclonal antibodies (mAbs) under mild conditions and to yield stable, target-specific agents. The utility of two novel BFCs, 1-Oxa-4,7,10-triazacyclododecane-5-S-(4-isothiocyanatobenzyl)-4,7,10-triacetic acid (p-SCN-Bn-Oxo-DO3A) and 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-4-S-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (p-SCN-Bn-PCTA), for mAb imaging with {sup 64}Cu were compared to the commonly used S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid (p-SCN-Bn-DOTA). The BFCs were conjugated to trastuzumab, which targets the HER2/neu receptor. {sup 64}Cu radiolabeling of the conjugates was optimized. Receptor binding was analyzed using flow cytometry and radioassays. Finally, PET imaging and biodistribution studies were done in mice bearing either HER2/neu-positive or HER2/neu-negative tumors. {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab were prepared at room temperature in >95% radiochemical yield (RCY) in <30 min, compared to only 88% RCY after 2 h for the preparation of {sup 64}Cu-DOTA-trastuzumab under the same conditions. Cell studies confirmed that the immunoreactivity of the mAb was retained for each of the bioconjugates. In vivo studies showed that {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab had higher uptake than the {sup 64}Cu-DOTA-trastuzumab at 24 h in HER2/neu-positive tumors, resulting in higher tumor to background ratios and better tumor images. By 40 h all three of the {sup 64}Cu-BFC-trastuzumab conjugates allowed for clear visualization of the HER2/neu-positive tumors but not the negative control tumor. The antibody conjugates of PCTA and Oxo-DO3A were shown to have superior {sup 64}Cu radiolabeling efficiency and stability compared to the analogous DOTA conjugate. In addition, {sup 64}Cu-PCTA and Oxo-DO3A antibody conjugates may facilitate earlier imaging with greater target to background ratios than

  9. A new bifunctional hybrid nanostructure as an active platform for photothermal therapy and MR imaging.

    Science.gov (United States)

    Khafaji, Mona; Vossoughi, Manouchehr; Hormozi-Nezhad, M Reza; Dinarvand, Rassoul; Börrnert, Felix; Irajizad, Azam

    2016-01-01

    As a bi-functional cancer treatment agent, a new hybrid nanostructure is presented which can be used for photothermal therapy by exposure to one order of magnitude lower laser powers compared to similar nanostructures in addition to substantial enhancment in magnetic resonance imaging (MRI) contrast. This gold-iron oxide hybrid nanostructure (GIHN) is synthesized by a cost-effective and high yield water-based approach. The GIHN is sheilded by PEG. Therefore, it shows high hemo and biocompatibility and more than six month stability. Alongside earlier nanostructures, the heat generation rate of GIHN is compareable with surfactnat-capped gold nanorods (GNRs). Two reasons are behind this enhancement: Firstly the distance between GNRs and SPIONs is adjusted in a way that the surface plasmon resonance of the new nanostructure is similar to bare GNRs and secondly the fraction of GNRs is raised in the hybrid nanostructure. GIHN is then applied as a photothermal agent using laser irradiation with power as low as 0.5 W.cm(-2) and only 32% of human breast adenocarcinoma cells could survive. The GIHN also acts as a dose-dependent transvers relaxation time (T2) MRI contrast agent. The results show that the GINH can be considered as a good candidate for multimodal photothermal therapy and MRI. PMID:27297588

  10. Bentonite used as Adsorbent Agent of the Coupling Adsorption Ultrafiltration of the Secondary Effluents for their Reuse

    Directory of Open Access Journals (Sweden)

    D. Abdessemed

    2008-01-01

    Full Text Available This present study has for principal objective to treat secondary effluents of the Staoueli purification plant (Algeria with the average characteristics in the Chemical Oxygen Demand (COD is 76 mg L-1and 16 NTU of turbidity by adsorption ultrafiltration coupling for its reuse in irrigation or in industry to reduce the water demand. A mineral ultrafiltration tubular membrane of CARBOSEP M2 (15 Kg mol-1 in dynamic mode with a transmembrane pressure ΔP = 1 bar and a cross flow velocity U = 3 m sec-1 was used for this purpose. The adsorbent choice was made on an Algerian bleaching ground: the bentonite available on the market with low cost. It has sorptives properties and ions exchange with specific area 250 m2 g-1. In the first step, we considered the organic matter adsorption on bentonite in static mode (jar test. The optimal conditions were determined corresponding to the best elimination of the Chemical Oxygen Demand with a final value equal to 30.6 mg L-1 and turbidity, in jar test with 1.5 NTU value for an optimal bentonite concentration equal to 10 g L-1. In the second step, the adsorption ultrafiltration coupling, showed a final value in COD equal to 9.2 mg L-1 and final turbidity equal to 1.2 NTU. An improvement of the permeate flux was showed equal to 48.8% for the optimal concentration bentonite 10 g L-1. The adsorption significantly improves the ultrafiltration performances.

  11. Portable Solid Phase Micro-Extraction Coupled with Ion Mobility Spectrometry System for On-Site Analysis of Chemical Warfare Agents and Simulants in Water Samples

    Directory of Open Access Journals (Sweden)

    Liu Yang

    2014-11-01

    Full Text Available On-site analysis is an efficient approach to facilitate analysis at the location of the system under investigation as it can result in more accurate, more precise and quickly available analytical data. In our work, a novel self-made thermal desorption based interface was fabricated to couple solid-phase microextraction with ion mobility spectrometry for on-site water analysis. The portable interface can be connected with the front-end of an ion mobility spectrometer directly without other modifications. The analytical performance was evaluated via the extraction of chemical warfare agents and simulants in water samples. Several parameters including ionic strength and extraction time have been investigated in detail. The application of the developed method afforded satisfactory recoveries ranging from 72.9% to 114.4% when applied to the analysis of real water samples.

  12. Use of silane coupling agent for surface modification of zinc oxide as inorganic filler and preparation of poly(amide–imide)/zinc oxide nanocomposite containing phenylalanine moieties

    Indian Academy of Sciences (India)

    Shadpour Mallakpour; Maryam Madani

    2012-06-01

    A series of novel poly(amide–imide)/ZnO nanocomposites with modified ZnO nanoparticles contents was prepared by ultrasonic irradiation. For this purpose, surface of ZnO nanoparticle was modified with -aminopropyltriethoxysilane as a coupling agent. Then the effect of surface modification on dispersion of nanoparticles, thermal stability and UV absorption property of the obtained nanocomposites were investigated. The resulting novel nanocomposites were characterized by several techniques. Field emission scanning electron microscopy and transmission electron microscopy analyses of the nanocomposites were performed in order to study the dispersion of nanofillers in the polymer matrix. According to thermogravimetry analysis results, the addition of ZnO nanoparticles improved thermal stability of the obtained nanocomposites. Since the resulting nanocomposites contain phenylalanine amino acid and ZnO, they are expected to be biocompatible as well as biodegradable.

  13. Indium-zinc-oxide electric-double-layer thin-film transistors gated by silane coupling agents 3-triethoxysilylpropylamine-graphene oxide solid electrolyte

    Science.gov (United States)

    Guo, Liqiang; Huang, Yukai; Shi, Yangyang; Cheng, Guanggui; Ding, Jianning

    2015-07-01

    Silane coupling agents 3-triethoxysilylpropyla-mine-graphene oxide (KH550-GO) solid electrolyte are prepared by spin coating process. A high proton conductivity of ~1.2   ×   10-3 Scm-1 is obtained at room temperature. A strong electric-double-layer (EDL) effect is observed due to the accumulation of protons at KH550-GO/IZO interface. Indium-Zinc-Oxide thin film transistors gated by KH550-GO solid electrolyte are self-assembled on ITO glass substrates. Good electrical performances are obtained, such as a low subthreshold swing of ~140 mV/dec., a high current on/off ratio of ~2.9   ×   107 and a high field-effect mobility of ~13.2 cm2 V-1 S-1, respectively.

  14. Indium-zinc-oxide electric-double-layer thin-film transistors gated by silane coupling agents 3-triethoxysilylpropylamine–graphene oxide solid electrolyte

    International Nuclear Information System (INIS)

    Silane coupling agents 3-triethoxysilylpropyla-mine-graphene oxide (KH550-GO) solid electrolyte are prepared by spin coating process. A high proton conductivity of ∼1.2   ×   10−3 Scm−1 is obtained at room temperature. A strong electric-double-layer (EDL) effect is observed due to the accumulation of protons at KH550-GO/IZO interface. Indium-Zinc-Oxide thin film transistors gated by KH550-GO solid electrolyte are self-assembled on ITO glass substrates. Good electrical performances are obtained, such as a low subthreshold swing of ∼140 mV/dec., a high current on/off ratio of ∼2.9   ×   107 and a high field-effect mobility of ∼13.2 cm2 V−1 S−1, respectively. (paper)

  15. Portable solid phase micro-extraction coupled with ion mobility spectrometry system for on-site analysis of chemical warfare agents and simulants in water samples.

    Science.gov (United States)

    Yang, Liu; Han, Qiang; Cao, Shuya; Yang, Jie; Yang, Junchao; Ding, Mingyu

    2014-01-01

    On-site analysis is an efficient approach to facilitate analysis at the location of the system under investigation as it can result in more accurate, more precise and quickly available analytical data. In our work, a novel self-made thermal desorption based interface was fabricated to couple solid-phase microextraction with ion mobility spectrometry for on-site water analysis. The portable interface can be connected with the front-end of an ion mobility spectrometer directly without other modifications. The analytical performance was evaluated via the extraction of chemical warfare agents and simulants in water samples. Several parameters including ionic strength and extraction time have been investigated in detail. The application of the developed method afforded satisfactory recoveries ranging from 72.9% to 114.4% when applied to the analysis of real water samples. PMID:25384006

  16. Results and Lessons Learned from a Coupled Social and Physical Hydrology Model: Testing Alternative Water Management Policies and Institutional Structures Using Agent-Based Modeling and Regional Hydrology

    Science.gov (United States)

    Murphy, J.; Lammers, R. B.; Prousevitch, A.; Ozik, J.; Altaweel, M.; Collier, N. T.; Kliskey, A. D.; Alessa, L.

    2015-12-01

    Water Management in the U.S. Southwest is under increasing scrutiny as many areas endure persistent drought. The impact of these prolonged dry conditions is a product of regional climate and hydrological conditions, but also of a highly engineered water management infrastructure and a complex web of social arrangements whereby water is allocated, shared, exchanged, used, re-used, and finally consumed. We coupled an agent-based model with a regional hydrological model to understand the dynamics in one richly studied and highly populous area: southern Arizona, U.S.A., including metropolitan Phoenix and Tucson. There, multiple management entities representing an array of municipalities and other water providers and customers, including private companies and Native American tribes are enmeshed in a complex legal and economic context in which water is bought, leased, banked, and exchanged in a variety of ways and on multiple temporal and physical scales. A recurrent question in the literature of adaptive management is the impact of management structure on overall system performance. To explore this, we constructed an agent-based model to capture this social complexity, and coupled this with a physical hydrological model that we used to drive the system under a variety of water stress scenarios and to assess the regional impact of the social system's performance. We report the outcomes of ensembles of runs in which varieties of alternative policy constraints and management strategies are considered. We hope to contribute to policy discussions in this area and connected and legislatively similar areas (such as California) as current conditions change and existing legal and policy structures are revised. Additionally, we comment on the challenges of integrating models that ostensibly are in different domains (physical and social) but that independently represent a system in which physical processes and human actions are closely intertwined and difficult to disentangle.

  17. High performance bi-functional quantum cascade laser and detector

    Science.gov (United States)

    Schwarz, Benedikt; Ristanic, Daniela; Reininger, Peter; Zederbauer, Tobias; MacFarland, Donald; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried

    2015-08-01

    An improved bi-functional quantum cascade laser and detector emitting and detecting around 6.8 μ m is demonstrated. The design allows a significantly higher laser performance, showing that bi-functional designs can achieve a comparable pulsed performance to conventional quantum cascade lasers. In particular, the device has a threshold current density of 3 kA / cm 2 , an output power of 0.47 W , and a total wall-plug efficiency of 4.5% in pulsed mode. Optimized electron extraction and the prevention of thermal backfilling allow higher duty cycles, operation up to 10%, with 15 mW average output power at room temperature without optimization of the laser cavity or coatings. At zero bias, the device has a responsivity of around 40 mA / W and a noise equivalent power of 80 pW / √{ Hz } at room temperature, which in on-chip configuration outperforms conventional uncooled discrete detectors.

  18. Applying an agent-based model of agricultural terraces coupled with a landscape evolution model to explore the impact of human decision-making on terraced terrain

    Science.gov (United States)

    Glaubius, Jennifer

    2016-04-01

    Agricultural terraces impact landscape evolution as a result of long-term human-landscape interactions, including decisions regarding terrace maintenance and abandonment. Modeling simulations are often employed to examine the sensitivity of landscapes to various factors, such as rainfall and land cover. Landscape evolution models, erosion models, and hydrological models have all previously been used to simulate the impact of agricultural terrace construction on terrain evolution, soil erosion, and hydrological connectivity. Human choices regarding individual terraces have not been included in these models to this point, despite recent recognition that maintenance and abandonment decisions alter transport and storage patterns of soil and water in terraced terrain. An agent-based model of human decisions related to agricultural terraces is implemented based on a conceptual model of agricultural terrace life cycle stages created from a literature review of terracing impacts. The agricultural terracing agent-based model is then coupled with a landscape evolution model to explore the role of human decisions in the evolution of terraced landscapes. To fully explore this type of co-evolved landscape, human decision-making and its feedbacks must be included in landscape evolution models. Project results may also have implications for management of terraced terrain based on how human choices in these environments affect soil loss and land degradation.

  19. A novel inorganic/organic composite membrane tailored by various organic silane coupling agents for use in direct methanol fuel cells

    Science.gov (United States)

    Li, Tao; Yang, Yong

    A series of organic silica/Nafion composite membranes has been prepared by using organic silane coupling agents (SCA) bearing different hydrophilic functional groups. The physico-chemical properties of the composite membranes have been characterized by electrochemical techniques, scanning electron microscopy (SEM), diffuse-reflection Fourier-transform infrared spectroscopy (DRFTIR), wide-angle X-ray diffraction (WAXRD), thermogravimetric analysis (TGA), and thermogravimetric mass spectrometry (TG-MS). It has been found that some organic silica/Nafion composite membranes modified by organic silane agents bearing amino groups exhibit extremely low methanol crossover and proton conductivity values, e.g., a composite membrane shows a proton conductivity that is about five orders of magnitude lower and a methanol permeability that is about three orders of magnitude lower than those of a Nafion117 membrane. However, under optimized conditions for controlling the basicity of the amino groups, we also obtained a composite membrane with 89% lower methanol permeability and 49% lower proton conductivity compared with Nafion117 membrane. The results clearly demonstrate that the diffusion of methanol and protons through the membrane can be controlled by adjusting the functional groups on the organic silica.

  20. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    Science.gov (United States)

    Zečević, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2016-01-01

    The ability to precisely control nanoscale features is increasingly exploited to develop and improve monofunctional catalysts1–4. Striking effects might also be expected in the case of bifunctional catalysts, which play an important role in hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel5–7. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called ‘intimacy criterion’8 has dictated the maximum distance between the two site types beyond which catalytic activity decreases. The lack of synthesis and material characterization methods with nanometer precision has long prevented in-depth exploration of the criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites8–11. Here we show for a bifunctional catalyst, comprised of an intimate mixture of zeolite Y and alumina binder and with platinum (Pt) metal controllably deposited20,21 on either the zeolite or the binder, that close proximity between metal and zeolite acid sites can be detrimental: the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains Pt on the binder, i.e. with a larger distance between metal and acid sites. Cracking of the large and complex hydrocarbon molecules typically derived from alternative sources such as gas-to-liquid technology, vegetable oil or algal oil6–7 should thus benefit especially from bifunctional catalysts that avoid locating Pt on the zeolite as the traditionally assumed optimal location. More generally, we anticipate that the ability to spatially organize different active sites at the nanoscale demonstrated here will benefit the further development and optimization of the newly emerging generation of multifunctional catalysts12–15. PMID:26659185

  1. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    Science.gov (United States)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-12-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

  2. Agent based Detecting Abnormal and Dynamic Coupled Behavior in Customer Relationship System use of Combined-Interestingness based Architecture

    Directory of Open Access Journals (Sweden)

    J.N.V.R SWARUP KUMAR

    2010-09-01

    Full Text Available Customer Relationship Management (CRM for short System emerged in the last decade to reveal the central role of the customer for the strategic positioning of a company. One of the most significant changes in the practice of marketing during the last decade is the shift in emphasis from a transaction orientation customer to the CRM. Now a day’s it is an important edge but now a necessary utensil for endurance. CRM competence is very important source for enterprises to build and sustain competitive advantage. With the extensive applications in CRM enterprises have plenty of customer data. Main vision of CRM is customer understanding, which is accurately done will helps to value customers and thus increases customer life time value. Effectively build CRM will maintain good relationships with customers. Companies have invested or are planning to empower huge amounts to implement CRM strategies, tools and infrastructures in-order to magnetize and retain profitable customers in today’s increasingly competitive markets. This paper introduces the detecting abnormal and dynamic coupled behavior in the CRM system and general architecture of CRM based on Domain Driven Data Mining (D3M for short and with advanced technologies for knowing winning strategies. It also discusses the important steps of designing the data warehouse and describes the meaning of D3M applied to the CRM and finally evolving of D3M to individual service are presented.

  3. Electroless Silver Plating on Hollow Glass Microsphere Modified by Silane Coupling Agent%空心玻璃微珠偶联化学镀银的研究

    Institute of Scientific and Technical Information of China (English)

    朱国庆; 文力; 张辉

    2012-01-01

    Surface of hollow glass microsphere was firstly modified by silane coupling agent, and then applying electroless silver plating directly. Surface morphology and structure of the coating were characterized by FTIR, SEM and XRD techniques. Results showed that compared with the colloidal palladium activation and silver ammonium solution activation methods, this silane coupling method could result in a uniform and compact coating with superior conductivity, higher adhesion and better silver utilization.%使用氨丙基三乙氧基硅烷偶联剂改性空心玻璃微珠表面,然后直接实施化学镀银,借助红外光谱、扫描电镜和X-射线衍射测试手段对偶联改性效果、镀层表面形貌和结构进行了表征.测试结果表明,与胶体钯活化法和硝酸银活化法化学镀银相比,空心玻璃微珠偶联表面改性直接化学镀银的镀层更为致密、均匀,银利用率高,导电性好,结合力强.

  4. Study of application properties of novel trisazo hetero bi-functional reactive dyes based on j-acid derivatives for cotton

    International Nuclear Information System (INIS)

    Three novel trisazo hetero bi-functional reactive dyes based on J-acid derivatives were prepared using the diazonium salt of [4-(4-sulphophenylazo-)-2,5-dimethylazobenzene-2-sulphonic acid] and a hetero bi-functional coupling component, derived from 1-hydroxy-6-aminonapthalene-3-sulphonic acid (J-acid), 1-hydroxy-6- methylaminonapthalene-3-sulphonic acid (methyl J-acid), and 1-hydroxy-6-aminonaphthalene-3,5-disulphonic acid (sulpho J-acid). On balance, the dye derived from sulpho J-acid displayed the most attractive set of technical properties, building up and fixing more efficiently than those derived from J-acid and methyl J-acid. In addition, the sulpho J-acid based dye offered better migration and, therefore, level dyeing and ease of wash off. (author)

  5. The Mycobacterium tuberculosis Rv2540c DNA sequence encodes a bifunctional chorismate synthase

    Directory of Open Access Journals (Sweden)

    Santos Diógenes S

    2008-04-01

    Full Text Available Abstract Background The emergence of multi- and extensively-drug resistant Mycobacterium tuberculosis strains has created an urgent need for new agents to treat tuberculosis (TB. The enzymes of shikimate pathway are attractive targets to the development of antitubercular agents because it is essential for M. tuberculosis and is absent from humans. Chorismate synthase (CS is the seventh enzyme of this route and catalyzes the NADH- and FMN-dependent synthesis of chorismate, a precursor of aromatic amino acids, naphthoquinones, menaquinones, and mycobactins. Although the M. tuberculosis Rv2540c (aroF sequence has been annotated to encode a chorismate synthase, there has been no report on its correct assignment and functional characterization of its protein product. Results In the present work, we describe DNA amplification of aroF-encoded CS from M. tuberculosis (MtCS, molecular cloning, protein expression, and purification to homogeneity. N-terminal amino acid sequencing, mass spectrometry and gel filtration chromatography were employed to determine identity, subunit molecular weight and oligomeric state in solution of homogeneous recombinant MtCS. The bifunctionality of MtCS was determined by measurements of both chorismate synthase and NADH:FMN oxidoreductase activities. The flavin reductase activity was characterized, showing the existence of a complex between FMNox and MtCS. FMNox and NADH equilibrium binding was measured. Primary deuterium, solvent and multiple kinetic isotope effects are described and suggest distinct steps for hydride and proton transfers, with the former being more rate-limiting. Conclusion This is the first report showing that a bacterial CS is bifunctional. Primary deuterium kinetic isotope effects show that C4-proS hydrogen is being transferred during the reduction of FMNox by NADH and that hydride transfer contributes significantly to the rate-limiting step of FMN reduction reaction. Solvent kinetic isotope effects and

  6. GST-TAT-SOD: Cell Permeable Bifunctional Antioxidant Enzyme-A Potential Selective Radioprotector.

    Science.gov (United States)

    Pan, Jianru; He, Huocong; Su, Ying; Zheng, Guangjin; Wu, Junxin; Liu, Shutao; Rao, Pingfan

    2016-01-01

    Superoxide dismutase (SOD) fusion of TAT was proved to be radioprotective in our previous work. On that basis, a bifunctional recombinant protein which was the fusion of glutathione S-transferase (GST), SOD, and TAT was constructed and named GST-TAT-SOD. Herein we report the investigation of the cytotoxicity, cell-penetrating activity, and in vitro radioprotective effect of GST-TAT-SOD compared with wild SOD, single-function recombinant protein SOD-TAT, and amifostine. We demonstrated that wild SOD had little radioprotective effect on irradiated L-02 and Hep G2 cells while amifostine was protective to both cell lines. SOD-TAT or GST-TAT-SOD pretreatment 3 h prior to radiation protects irradiated normal liver cells against radiation damage by eliminating intracellular excrescent superoxide, reducing cellular MDA level, enhancing cellular antioxidant ability and colony formation ability, and reducing apoptosis rate. Compared with SOD-TAT, GST-TAT-SOD was proved to have better protective effect on irradiated normal liver cells and minimal effect on irradiated hepatoma cells. Besides, GST-TAT-SOD was safe for normal cells and effectively transduced into different organs in mice, including the brain. The characteristics of this protein suggest that it may be a potential radioprotective agent in cancer therapy better than amifostine. Fusion of two antioxidant enzymes and cell-penetrating peptides is potentially valuable in the development of radioprotective agent. PMID:27313832

  7. GST-TAT-SOD: Cell Permeable Bifunctional Antioxidant Enzyme—A Potential Selective Radioprotector

    Science.gov (United States)

    Pan, Jianru; He, Huocong; Su, Ying; Zheng, Guangjin; Wu, Junxin; Liu, Shutao; Rao, Pingfan

    2016-01-01

    Superoxide dismutase (SOD) fusion of TAT was proved to be radioprotective in our previous work. On that basis, a bifunctional recombinant protein which was the fusion of glutathione S-transferase (GST), SOD, and TAT was constructed and named GST-TAT-SOD. Herein we report the investigation of the cytotoxicity, cell-penetrating activity, and in vitro radioprotective effect of GST-TAT-SOD compared with wild SOD, single-function recombinant protein SOD-TAT, and amifostine. We demonstrated that wild SOD had little radioprotective effect on irradiated L-02 and Hep G2 cells while amifostine was protective to both cell lines. SOD-TAT or GST-TAT-SOD pretreatment 3 h prior to radiation protects irradiated normal liver cells against radiation damage by eliminating intracellular excrescent superoxide, reducing cellular MDA level, enhancing cellular antioxidant ability and colony formation ability, and reducing apoptosis rate. Compared with SOD-TAT, GST-TAT-SOD was proved to have better protective effect on irradiated normal liver cells and minimal effect on irradiated hepatoma cells. Besides, GST-TAT-SOD was safe for normal cells and effectively transduced into different organs in mice, including the brain. The characteristics of this protein suggest that it may be a potential radioprotective agent in cancer therapy better than amifostine. Fusion of two antioxidant enzymes and cell-penetrating peptides is potentially valuable in the development of radioprotective agent. PMID:27313832

  8. GST-TAT-SOD: Cell Permeable Bifunctional Antioxidant Enzyme—A Potential Selective Radioprotector

    Directory of Open Access Journals (Sweden)

    Jianru Pan

    2016-01-01

    Full Text Available Superoxide dismutase (SOD fusion of TAT was proved to be radioprotective in our previous work. On that basis, a bifunctional recombinant protein which was the fusion of glutathione S-transferase (GST, SOD, and TAT was constructed and named GST-TAT-SOD. Herein we report the investigation of the cytotoxicity, cell-penetrating activity, and in vitro radioprotective effect of GST-TAT-SOD compared with wild SOD, single-function recombinant protein SOD-TAT, and amifostine. We demonstrated that wild SOD had little radioprotective effect on irradiated L-02 and Hep G2 cells while amifostine was protective to both cell lines. SOD-TAT or GST-TAT-SOD pretreatment 3 h prior to radiation protects irradiated normal liver cells against radiation damage by eliminating intracellular excrescent superoxide, reducing cellular MDA level, enhancing cellular antioxidant ability and colony formation ability, and reducing apoptosis rate. Compared with SOD-TAT, GST-TAT-SOD was proved to have better protective effect on irradiated normal liver cells and minimal effect on irradiated hepatoma cells. Besides, GST-TAT-SOD was safe for normal cells and effectively transduced into different organs in mice, including the brain. The characteristics of this protein suggest that it may be a potential radioprotective agent in cancer therapy better than amifostine. Fusion of two antioxidant enzymes and cell-penetrating peptides is potentially valuable in the development of radioprotective agent.

  9. Determination of trace levels of dissolved vanadium in seawater by use of synthetic complexing agents and inductively coupled plasma-atomic emission spectroscopy (ICP-AES)

    Energy Technology Data Exchange (ETDEWEB)

    Abbasse, G.; Ouddane, B.; Fischer, J.C. [Univ. des Sciences et Technologies et Lille, Lab. de Chimie Analytique et Marine (ELICO), UPRESA CNRS 8013, Villeneuve d' Ascq (France)

    2002-11-01

    In the determination of traces of dissolved vanadium in complex matrices such as seawater, separation and enrichment from the matrix is of special importance. A wide variety of methods has been proposed for preconcentration, depending to the nature of samples and the methods to be used for measurement. Among these methods separation techniques based on sorption on to chelating resins seem convenient, rapid, and capable of achieving a high concentration factor. The methods proposed in this paper are based on the transformation of all dissolved vanadium species in seawater into organic complexes by use of synthetic complexing agents such as dithizone, luminol, or 8-hydroxyquinoline; the resulting vanadium-organic complexes were sorbed on to a C{sub 18} column at a flow rate of 5 mL min{sup -1}. The vanadium sorbed on the C{sub 18} columns was then stripped by use of nitric acid (2 mol L{sup -1}) and analysed by inductively coupled plasma-atomic emission spectroscopy, ICP-AES. This method was optimised and use of other chelating resins, such as chelamine, chelex-100, and immobilised 8-hydroxyquinoline and was compared by passing seawater samples directly over the resins. The experimental conditions (pH, acid used for elution, and contact time between the liquid sample and the resin) were optimised. The results were compared for all the resins used and were indicative of excellent and coherent reproducibility. (orig.)

  10. Surface modification of Fe2TiO5 nanoparticles by silane coupling agent: Synthesis and application in proton exchange composite membranes.

    Science.gov (United States)

    Salarizadeh, Parisa; Javanbakht, Mehran; Pourmahdian, Saeed; Bagheri, Ahmad; Beydaghi, Hossein; Enhessari, Morteza

    2016-06-15

    Modifying surfaces of nanoparticles with silane coupling agent provides a simple method to alter their surface properties and improve their dispersibility in organic solvents and polymer matrix. Fe2TiO5 nanoparticles (IT) were modified with 3-aminopropyltriethoxysilane (APTES) as novel reinforcing filler for proton exchange membranes. The main operating parameters such as reaction time (R.T), APTES/IT and triethylamine (TEA)/IT ratios have been optimized for maximum grafting efficiency. The optimum conditions for R.T, APTES/IT and TEA/IT ratios were 6h, 4 and 0.3 respectively. It was observed that the APTES/IT and TEA/IT ratios were the most significant parameters affecting the grafting percentage. Modified nanoparticles were characterized using FT-IR, TGA, SEM, TEM and XRD techniques. Effects of modified nanoparticles in proton exchange membrane fuel cells (PEMFC) were evaluated. The resulting nanocomposite membranes exhibited higher proton conductivity in comparison with pristine SPPEK and SPPEK/IT membranes. This increase is attributed to connectivity of the water channels which creates more direct pathways for proton transport. Composite membrane with 3% AIT (6.46% grafting amount) showed 0.024Scm(-1) proton conductivity at 25°C and 149mWcm(-2) power density (at 0.5V) at 80°C which were about 243% and 51%, respectively higher than that of pure SPPEK. PMID:27023633

  11. Chemical synthesis and characterization of hydroxyapatite (HAp)-poly (ethylene co vinyl alcohol) (EVA) nanocomposite using a phosphonic acid coupling agent for orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Nabakumar; Mohapatra, Sasmita [Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur - 721302, West Bengal (India); Bhargava, Parag [Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai-400076 (India); Pramanik, Panchanan [Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur - 721302, West Bengal (India)], E-mail: pramanik@chem.iitkgp.ernet.in

    2009-01-01

    A novel bio-analogue hydroxyapatite (HAp)-poly (ethylene co vinyl alcohol) (EVA) nanocomposite has been synthesized by a solution-based chemical methodology with varying HAp contents from 10 to 60% (w/w). The surface of HAp particles has been modified with 2-carboxyethylphosphonic acid in order to enhance the interfacial bonding interaction between HAp and EVA, and hence to improve the mechanical properties of the composite. The interfacial modification has been investigated through Fourier transform infrared absorption spectra (FTIR), X-ray diffraction (XRD) and thermal analyses. The surface morphology of the composite and the homogeneous dispersion of nanoparticles in the polymer matrix have been investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. The use of phosphonic acid coupling agent promotes the uniform dispersion of HAp particles in the polymer matrix with strong particle-polymer interfacial bonding, which leads to a significant improvement in mechanical properties of the composite. The cell viability test indicates that the HAp-EVA nanocomposite is cytocompatible. The developed HAp-EVA nanocomposite may be potentially used as bone substitutes.

  12. Chemical synthesis and characterization of hydroxyapatite (HAp)-poly (ethylene co vinyl alcohol) (EVA) nanocomposite using a phosphonic acid coupling agent for orthopedic applications

    International Nuclear Information System (INIS)

    A novel bio-analogue hydroxyapatite (HAp)-poly (ethylene co vinyl alcohol) (EVA) nanocomposite has been synthesized by a solution-based chemical methodology with varying HAp contents from 10 to 60% (w/w). The surface of HAp particles has been modified with 2-carboxyethylphosphonic acid in order to enhance the interfacial bonding interaction between HAp and EVA, and hence to improve the mechanical properties of the composite. The interfacial modification has been investigated through Fourier transform infrared absorption spectra (FTIR), X-ray diffraction (XRD) and thermal analyses. The surface morphology of the composite and the homogeneous dispersion of nanoparticles in the polymer matrix have been investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. The use of phosphonic acid coupling agent promotes the uniform dispersion of HAp particles in the polymer matrix with strong particle-polymer interfacial bonding, which leads to a significant improvement in mechanical properties of the composite. The cell viability test indicates that the HAp-EVA nanocomposite is cytocompatible. The developed HAp-EVA nanocomposite may be potentially used as bone substitutes

  13. Analysis of sulfate metabolites of the doping agents oxandrolone and danazol using high performance liquid chromatography coupled to tandem mass spectrometry.

    Science.gov (United States)

    Rzeppa, S; Viet, L

    2016-09-01

    The direct detection of sulfate conjugates of anabolic androgenic steroids (AAS) can be a powerful tool in doping control analysis. By skipping the solvolysis step analysis time can be reduced, and due to long term sulfate metabolites the detection time can be significantly extended as demonstrated for some AAS. This study presents the successful identification of sulfate metabolites of the doping agents oxandrolone and danazol in excretion urines by high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The sulfate conjugate of 17β-hydroxymethyl-17α-methyl-18-nor-2-oxa-5α-androsta-13-en-3-one could be identified as a new metabolite of oxandrolone. Sulfate conjugates of the danazol metabolites ethisterone and 2α-hydroxymethylethisterone were identified in an excretion urine for the first time. In addition, these sulfate conjugates were synthesized successfully. For a confirmation analysis, the number of analytes can be increased by additional sulfate conjugates of danazol metabolites (2-hydroxymethyl-1,2-dehydroethisterone and 6β-hydroxy-2-hydroxymethylethisterone), which were also identified for the first time. The presented validation data underline the suitability of the identified sulfate conjugates for doping analysis with regard to the criteria given by the technical documents of the World Anti-Doping Agency (WADA). PMID:27394004

  14. Structural analysis of a recombinant plant bifunctional nuclease TBN1

    Czech Academy of Sciences Publication Activity Database

    Kovaľ, Tomáš; Lipovová, P.; Podzimek, Tomáš; Matoušek, Jaroslav; Dušková, Jarmila; Skálová, Tereza; Štěpánková, Andrea; Hašek, Jindřich; Dohnálek, Jan

    Vol. no 1. Praha : Czech and Slovak Crystallographic Association, 2011. s. 29. ISSN 1211-5894. [Discussions in Structural Molecular Biology /9./. 24.03.2011-26.03.2011, Nové Hrady] R&D Projects: GA ČR GA202/06/0757; GA ČR GA310/09/1407; GA ČR GA521/09/1214 Grant ostatní: AVČR(CZ) Praemium Academiae Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z50510513; CEZ:AV0Z40500505 Keywords : bifunctional nuclease * cancer * x-ray analysis Subject RIV: BM - Solid Matter Physics ; Magnetism

  15. 钛酸酯偶联剂含量对磁流变液性能的影响%Effect of Titanate Coupling Agent Content on Performance of Magnetorheological Fluid

    Institute of Scientific and Technical Information of China (English)

    唐泳波; 马平; 龚政

    2011-01-01

    A novel silicon-oil-based magnetorheological fluid (MRF) was prepared using titanate coupling agent with different contents as stabilizer and carboxyl iron powder as the magnetic particles. The effects of different volume fractions titanate coupling agents on sedimentation stability and shear properties of the MRF were compared.The results show that with the increase of the titanate coupling agent content the sedimentation stability of the MRF decreased. The MRF added 2vol% titanate coupling agent had the best sedimentation stability, while added 4vol%titanate coupling agent had a shear strength of 20 kPa when the magnetic field intensity was 400 mT. The quantitative relationship between shear strength and magnetic field intensity as well as the content of titanate was obtained when the volume fraction of carboxyl iron powder in MRF was 35vol%.%分别以不同含量的钛酸酯偶联剂为稳定剂,以羰基铁粉为磁性颗粒制备了硅油基磁流变液,比较了不同体积分数钛酸酯偶联剂对磁流变液沉降稳定性和剪切性能的影响.结果表明:磁流变液的沉降稳定性随钛酸酯偶联剂含量增多而下降,添加2%时具有最好的沉降稳定性;添加4%钛酸酯偶联剂时,在400 mT磁场下剪切屈服强度可达20 kPa;并得到了羰基铁粉体积分数为35%时磁流变液的剪切屈服强度、磁场强度及钛酸酯含量的定量关系式.

  16. DNA repair modulates the vulnerability of the developing brain to alkylating agents

    OpenAIRE

    Kisby, G.E.; Olivas, A.; Park, T.; Churchwell, M.; Doerge, D; Samson, L. D.; Gerson, S L; Turker, M.S.

    2008-01-01

    Neurons of the developing brain are especially vulnerable to environmental agents that damage DNA (i.e., genotoxicants), but the mechanism is poorly understood. The focus of the present study is to demonstrate that DNA damage plays a key role in disrupting neurodevelopment. To examine this hypothesis, we compared the cytotoxic and DNA damaging properties of the methylating agents methylazoxymethanol (MAM) and dimethyl sulfate (DMS) and the mono- and bifunctional alkylating agents chloroethyla...

  17. Novel bis-silane/TiO2 bifunctional hybrid films for metal corrosion protection both under ultraviolet irradiation and in the dark

    International Nuclear Information System (INIS)

    Novel silane/TiO2 bifunctional hybrid films based on highly protective bis-[triethoxysilylpropyl]-tetrasulfide silane were prepared on stainless steel substrates. With the addition of silane agent, TiO2 particles can be more easily immobilized and better dispersed onto the substrates, leading to significant enhancement of the photocathodic protection to substrates under ultraviolet irradiation. Meanwhile, due to the high protectiveness of the bis-silane matrix, the obtained hybrid films also have a high barrier performance if they are used in the dark

  18. Preparation and characterization of EPDM/silica composites prepared through non-hydrolytic sol-gel method in the absence and presence of a coupling agent

    Directory of Open Access Journals (Sweden)

    T. H. Mokhothu

    2014-11-01

    Full Text Available Ethylene propylene diene monomer (EPDM rubber composites containing in situ generated silica particles was prepared through a non-hydrolytic sol-gel (NHSG method with silicon tetrachloride as precursor. The silica particles were homogenously dispersed in the EPDM matrix, but there were agglomerates at high silica contents. The swelling experiments showed a decrease in the crosslinking density of the vulcanized rubber due to the presence of the silica particles for both the composites prepared in the presence and absence of a coupling agent, bis-[-3-(triethoxysilyl-propyl]-tetrasulfide (TESPT. Unlike the composites prepared through a hydrolytic sol-gel (HSG method with TEOS as precursor, the TESPT did not seem to take part in the sol-gel reaction. The presence of TESPT influenced the interaction and dispersion of the silica particles in the EPDM matrix, which gave rise to increased thermal stability of the EPDM when compared to the composites prepared in the absence of TESPT. However, ethylene chloride and TESPT evaporated from the samples at temperatures below the EPDM decomposition range. The values of the Nielsen model parameters, that gave rise to a good agreement with the experimentally determined Young’s modulus values, indicated improved dispersion and reduced size of the silica aggregates in the EPDM matrix. There was also good agreement between the storage modulus and Young’s modulus values. The filler effectiveness (Factor C indicated a mechanical stiffening effect and a thermal stability contribution by the filler, while the damping reduction (DR values confirmed that the EPDM interacted strongly with the well dispersed silica particles and the polymer chain mobility was restricted. The tensile properties, however, were in some cases worse than those for the samples prepared through the HSG method in the presence of TEOS.

  19. Composite Films of Poly(vinyl alcohol) and Bifunctional Cross-linking Cellulose Nanocrystals.

    Science.gov (United States)

    Sirviö, Juho Antti; Honkaniemi, Samuli; Visanko, Miikka; Liimatainen, Henrikki

    2015-09-01

    Long and flexible cellulose nanofibrils or stiff and short cellulose nanocrystals (CNCs) are both promising lightweight materials with high strength and the potential to serve as reinforcing agents in many polymeric materials. In this study, bifunctional reactive cellulose nanocrystals (RCNCs) with carboxyl and aldehyde functionalities were used as reinforcements to prepare acetal-bonding cross-linked poly(vinyl alcohol) (PVA) films. Two RCNCs were obtained through the mechanical homogenization of partially carboxylated dialdehyde cellulose (DAC) with a residual aldehyde content of 0.55 and 1.93 mmol/g and a carboxyl content of 1.65 and 1.93 mmol/g, respectively. The mechanical, thermal, and barrier properties of PVA-RCNC films with a variable mass ratio of RCNCs (0.5-10%) were determined. Reference CNCs without reactive aldehydes were obtained through the reduction of aldehyde functionalities to primary hydroxide groups, and their reinforcing effect was compared to RCNCs. With the addition of 10% acetal-bonding RCNCs with respect to PVA weight, the tensile strength and Young's modulus were up to 2-fold greater than those of pure PVA film. An addition of only 0.5% RCNCs improved the tensile strength of the PVA film by 66% and the modulus by 61%. In comparison, a significantly lower reinforcing effect (19% with CNC loading of 0.5%) was found using reference CNCs. PVA's effective oxygen barrier and thermal properties were preserved when RCNCs were introduced into the films. PMID:26280660

  20. Synthesis and Characterization of a New Bifunctional Dye Containing Spirobenzopyran and Cinnamoyl Moiety

    Institute of Scientific and Technical Information of China (English)

    申凯华; 崔东熏

    2005-01-01

    A novel bifunctional dye containing spirobenzopyran and cinnaznoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated.The colourless bifunctional dye in film or solution exhibits unusual photochromism through structural and geometrical transformation from spirobenzopyran to merocyanine accompanying with photocrosslinking reaction in cinnamoyl moieties. Two kinds of photochemical reaction were achieved by irradiation at the different wavelengths of monochrome UV light (275 nm, 365 nm) selectively. The photochromic process of the bifunctional dye was discussed and the dynamic behaviors of the decolorization process were investigated.

  1. Novel bifunctional anthracycline and nitrosourea chemotherapy for human bladder cancer: analysis in a preclinical survival model.

    Science.gov (United States)

    Glaves, D; Murray, M K; Raghavan, D

    1996-08-01

    A hybrid drug [N-2-chloroethylnitrosoureidodaunorubicin (AD312)] that combines structural and functional features of both anthracyclines and nitrosoureas was evaluated in a preclinical survival model of human bladder cancer. To measure the therapeutic activity of AD312, UCRU-BL13 transitional cell carcinoma cells were grown as xenografts in nude mice, and tumor growth rates were compared after i.v. administration of the drug at three dose levels. AD312 treatment at 45 and 60 mg/kg achieved 7-10-fold inhibition of tumor growth and increased host survival by 156 and 249%, respectively. Doses of 60 mg/kg showed optimal therapeutic efficacy, with sustained tumor growth inhibition, an over 2-fold increase in life span, and 40% of mice tumor free ("cured") at 120 days. Tumors were unresponsive to maximum tolerated doses of doxorubicin, a standard anthracycline used as a single agent and in combination therapies for bladder cancer. 1,3-Bis-[2-chloroethyl]-1-nitrosourea was used as a control for the apparently enhanced response of human tumors in murine hosts to nitrosoureas. 1, 3-Bis-[2-chloroethyl]-1-nitrosourea administered in three injections of 20 mg/kg did not cure mice but temporarily inhibited tumor growth by 70% and prolonged survival by 55%; its activity in this model suggests that it may be included in the repertoire of alkylating agents currently used for treatment of bladder cancers. AD312 showed increased antitumor activity with less toxicity than doxorubicin, and its bifunctional properties provide the opportunity for simultaneous treatment of individual cancer cells with two cytotoxic modalities as well as treatment of heterogeneous populations typical of bladder cancers. This novel cytotoxic drug cured doxorubicin-refractory disease and should be investigated for the clinical management of bladder cancer. PMID:9816302

  2. Crystallization of recombinant bifunctional nuclease TBN1 from tomato

    International Nuclear Information System (INIS)

    Glycosylated recombinant bifunctional nuclease from tomato has been crystallized and preliminary X-ray diffraction analysis was performed. The endonuclease TBN1 from Solanum lycopersicum (tomato) was expressed in Nicotiana benthamiana leaves and purified with suitable quality and in suitable quantities for crystallization experiments. Two crystal forms (orthorhombic and rhombohedral) were obtained and X-ray diffraction experiments were performed. The presence of natively bound Zn2+ ions was confirmed by X-ray fluorescence and by an absorption-edge scan. X-ray diffraction data were collected from the orthorhombic (resolution of 5.2 Å) and rhombohedral (best resolution of 3.2 Å) crystal forms. SAD, MAD and MR methods were applied for solution of the phase problem, with partial success. TBN1 contains three Zn2+ ions in a similar spatial arrangement to that observed in nuclease P1 from Penicillium citrinum

  3. Chemoselective Reactivity of Bifunctional Cyclooctynes on Si(001)

    CERN Document Server

    Reutzel, Marcel; Lipponer, Marcus A; Länger, Christian; Höfer, Ulrich; Koert, Ulrich; Dürr, Michael

    2016-01-01

    Controlled organic functionalization of silicon surfaces as integral part of semiconductor technology offers new perspectives for a wide range of applications. The high reactivity of the silicon dangling bonds, however, presents a major hindrance for the first basic reaction step of such a functionalization, i.e., the chemoselective attachment of bifunctional organic molecules on the pristine silicon surface. We overcome this problem by employing cyclooctyne as the major building block of our strategy. Functionalized cyclooctynes are shown to react on Si(001) selectively via the strained cyclooctyne triple bond while leaving the side groups intact. The achieved selectivity originates from the distinctly different adsorption dynamics of the separate functionalities: A direct adsorption pathway is demonstrated for cyclooctyne as opposed to the vast majority of other organic functional groups. The latter ones react on Si(001) via a metastable intermediate which makes them effectively unreactive in competition wi...

  4. Preparation and Characterization of Organically Modified Sepiolite by Silane Coupling Agent%硅烷偶联剂改性海泡石的制备及表征

    Institute of Scientific and Technical Information of China (English)

    李计元; 马玉书; 张婷婷; 王长平; 王宝河

    2011-01-01

    为了解决海泡石纤维在聚合物体系中的相容性和分散性问题,用硅烷偶联剂对海泡石进行表面修饰.以水在海泡石表面的接触角为指标.采用正交实验法研究了硅烷用量、预处理温度、反应温度和反应时间对硅烷改性海泡石润湿性的影响,并用XRD、FTIR和SEM对试样进行表征.结果表明:硅烷改性海泡石的最佳制备工艺为硅烷用量为2mol/30g海泡石,预处理温度为50℃,反应温度90℃和反应时间2h.硅烷对海泡石有良好的修饰作用,可使海泡石由亲水状态转变为疏水状态,接触角达到140°以上.%To improve the chemical compatibility and dispersion of the sepiolite in polymers, silane coupling agent was used to modify acid-treated sepiolite. The orthogonal experiment was used to analyze the effects of silane dosage, pre-treated temperature, reaction temperature and reaction time on the wettability of organically modified sepiolite. The effects on the structure performance of modified sepiolite were characterized by XRD, FTIR, SEM and contact angle analyse instruments. The results showed that the best technological conditions of organically modified sepiolite were as follows: dosage of silane 2 mol/30g sepiolite, pre-treated temperature 50 ℃, reaction temperature 90 ℃ and reaction time 2 h. Sepiolite surface can be well modified by treating with organosilane, resulting in the hydrophilic surface transforming to hydrophobic state, the contact angle is above 140°.

  5. Novel 16-substituted bifunctional derivatives of huperzine B: multifunctional cholinesterase inhibitors

    OpenAIRE

    Shi, Yu-fang; Zhang, Hai-Yan; Wang, Wei; Fu, Yan; Xia, Yu; Tang, Xi-can; Bai, Dong-lu; He, Xu-chang

    2009-01-01

    Aim: To design novel bifunctional derivatives of huperzine B (HupB) based on the concept of dual binding site of acetylcholinesterase (AChE) and evaluate their pharmacological activities for seeking new drug candidates against Alzheimer's disease (AD). Methods: Novel 16-substituted bifunctional derivatives of HupB were synthesized through chemical reactions. The inhibitory activities of the derivatives toward AChE and butyrylcholinesterase (BuChE) were determined in vitro by modified Ellman's...

  6. Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation

    DEFF Research Database (Denmark)

    Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong;

    bifunctional requirement, which demands both adsorption and water oxidation sites. In this contribution, we explore the possibility of using Pt-Si alloys to fulfill this bifunctional requirement. Silicon, a highly oxophillic element, is alloyed into Pt as a site for water oxidation, while Pt serves as a CO...... adsorption site. We will discuss the enhanced activity of Pt-Si alloys for small organic molecule oxidation, which can be attributed to the improved CO electro-oxidation kinetics on Pt-Si....

  7. Synthesis of chelating agents for actinium 225 complexation and its application in radioimmunotherapy

    International Nuclear Information System (INIS)

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine 131 may not be the best isotope for tumor therapy because of its limited specific activity, low beta-energy, relatively long half life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelator that can hold radio-metals with high stability under physiological conditions are essential to avoid excessive damage to non-target cells; Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. Therefore, we have developed a new simple and efficient synthesis pathway of 2-(4-iso-thio-cyanate-benzyl)-1,4,7,10,13,16- hexa-aza-cyclo-hexadecane- 1,4,7,10,13,16-hexa-acetic acid, though functionalized on the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (author)

  8. Bifunctional chelates of Rh-105 and Au-199 as potential radiotherapeutic agents

    Energy Technology Data Exchange (ETDEWEB)

    Troutner, D.E.; Schlemper, E.O.

    1987-08-31

    Since last year we have (1) Investigated the production of Rh-105 by the Szilard-Chalmers process using Ru(acac){sub 3} targets, (2) Synthesized several new ligands and their rhodium complexes, (3) Done preliminary studies of the radiochemical properties of some of these complexes of Rh-105 at 10{sup -4} -10{sup -3} M concentration, and (4) Done preliminary animal studies on one of the complexes.

  9. Study of the leaching of heavy metals from waste water sludge and incinerator's ash, using coupled thermostated columns and DTPA as complex agent; Estudio de la extraccion de metales pesados de lodos y cenizas de aguas residuales usando columnas termostatizadas acopladas y DTPA como agente complejante

    Energy Technology Data Exchange (ETDEWEB)

    Vite T, J.; Vite T, M.; Guerrero D, J.; Carreno de Leon, M.C. [Departamento de Estudios del Ambiente, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2000-07-01

    We studied the metallic composition from waste water sludge and incinerators ashes of an incinerator located in Toluca, Mexico, the qualitative studies were made using the Activation Analysis technique, and fluorescence X-ray techniques. The quantitative analysis of heavy metals in the wastes were made using Inductively coupled plasma atomic emission spectrometry (Icp-Aes). For leaching the samples, we used four coupled thermostated columns, each one had a p H of 2,5, 7 and 10. The flux of the air was of 1600 cc/min. The temperature was maintain constant in 60 Centigrade using a thermostated system. For this study we used 100 g of wastes mixed with mineral acid or sodium hydroxide to reach p H 2,5,7 and 10. We added a reducing and tensoactive agents and finally DTPA as complex agent. With this method, we obtain a better leaching efficiency using a complex agent. However the high DTPA cost, make this process expansive that is why we recommend to work with another classes of complex agents, that be cheaper to leach metals of different chemistry matrix. (Author)

  10. Study of the effect of ionizing radiation on composites of wood flour in polypropylene matrix using barium titanate as coupling agent

    International Nuclear Information System (INIS)

    The purpose of this work was to study the effects of ionizing radiation on the properties of wood flour composites in polypropylene matrix, using barium titanate as a coupling agent and the reactive monomer tripropylene glycol diacrylate (TPDGA). An electron accelerator was used in the study as the radiation source. The physical properties of virgin compounds and of the polypropylene/wood flour composite, with and without barium titanate and TPDGA addition, were investigated. The composites were developed from the load treatment, which first consisted of incorporating additives to the wood flour reinforcement and after that, the fusion process of polypropylene and composite mixing in a 'calander'. Subsequently, the samples to be irradiated and submitted to thermal and mechanical assays were molded by injection. The mechanical properties (hardness, impact resistance and molten fluidity index (MFI)), as well as the thermal properties (HDT and Vicat) of the composites were determined. The investigated compositions consisted of polypropylene/wood flour, polypropylene/wood flour with barium titanate and polypropylene/wood flour with barium titanate and TPDGA, using different wood flour concentrations of 10 por cent, 15 por cent and 20 por cent in the polypropylene matrix. The samples were separated in groups and irradiated to doses of 10 kGy and 20 kGy in the samples of the essays of traction. Besides these doses, it was also used doses of 15 kGy and 25 kGy to be observed the behavior of the sample of the sample due to the increase of the radiation. These doses were chosen to show that with low doses the composite material presents reticulation, what represents a viable commercial option. There was a reduction of the flow rate for the composites containing wood flour, being this reduction more effective in the presence of TiBa. The superficial treatment using TPDGA monomer influence in the composite samples because it acted as a plastic additive becoming the sample

  11. Gold-Copper Nanoparticles: Nanostructural Evolution and Bifunctional Catalytic Sites

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Jun; Shan, Shiyao; Yang, Lefu; Mott, Derrick; Malis, Oana; Petkov, Valeri; Cai, Fan; Ng, Mei; Luo, Jin; Chen, Bing H.; Engelhard, Mark H.; Zhong, Chuan-Jian

    2012-12-12

    Understanding of the atomic-scale structure is essential for exploiting the unique catalytic properties of any nanoalloy catalyst. This report describes novel findings of an investigation of the nanoscale alloying of gold-copper (AuCu) nanoparticles and its impact on the surface catalytic functions. Two pathways have been explored for the formation of AuCu nanoparticles of different compositons, including wet chemical synthesis from mixed Au- and Cu-precursor molecules, and nanoscale alloying via an evolution of mixed Au- and Cu-precursor nanoparticles near the nanoscale melting temperatures. For the evolution of mixed precursor nanoparticles, synchrotron x-ray based in-situ real time XRD was used to monitor the structural changes, revealing nanoscale alloying and reshaping towards an fcc-type nanoalloy (particle or cube) via a partial melting–resolidification mechanism. The nanoalloys supported on carbon or silica were characterized by in-situ high-energy XRD/PDFs, revealing an intriguing lattice "expanding-shrinking" phenomenon depending on whether the catalyst is thermochemically processed under oxidative or reductive atmosphere. This type of controllable structural changes is found to play an important role in determining the catalytic activity of the catalysts for carbon monoxide oxidation reaction. The tunable catalytic activities of the nanoalloys under thermochemically oxidative and reductive atmospheres are also discussed in terms of the bifunctional sites and the surface oxygenated metal species for carbon monoxide and oxygen activation.

  12. Novel Polyamide Proton Exchange Membranes with Bi-Functional Sulfonimide Bridges for Fuel Cell Applications

    International Nuclear Information System (INIS)

    Graphical abstract: A polymer proton conductor crosslinked with bi-functional sulfonamide bridges is synthesized for PEM fuel cell applications. The architecture simultaneously enhances mechanical strength and improves water retention of the PEMs. With an appropriate degree of crosslinking, the bi-functional PEM exhibits comparable performance to that of a commercial Nafion membrane tested in a direct methanol fuel cell. - Abstract: We design and successfully synthesize non-fluorinated polyamides with controlled crosslinking using sulfonimide as a bi-functional linker to interconnect polymer backbones and as a bridge for proton conduction. We show that the bi-functional linkers are highly beneficial not only for mechanical enforcement of the proton exchange membranes but also for enhancement of water retention capacity. With an appropriate degree of crosslinking, higher water retention capacity than that of commercial Nafion membranes can be obtained. The maximum proton conductivity of the membranes is found to be as high as 0.139 S cm−1 at 80 °C, almost the same as that of a Nafion 117 membrane. Excellent performance with the bi-functional polymer membranes in an air-breathing direct methanol fuel cell prototype, comparable to the performance of a Nafion 117 membrane, is demonstrated

  13. Novel configuration of bifunctional air electrodes for rechargeable zinc-air batteries

    Science.gov (United States)

    Li, Po-Chieh; Chien, Yu-Ju; Hu, Chi-Chang

    2016-05-01

    A novel configuration of two electrodes containing electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) pressed into a bifunctional air electrode is designed for rechargeable Zn-air batteries. MOC/25BC carbon paper (MOC consisting of α-MnO2 and XC-72 carbon black) and Fe0.1Ni0.9Co2O4/Ti mesh on this air electrode mainly serve as the cathode for the ORR and the anode for the OER, respectively. The morphology and physicochemical properties of Fe0.1Ni0.9Co2O4 are investigated through scanning electron microscopy, inductively coupled plasma-mass spectrometry, and X-ray diffraction. Electrochemical studies comprise linear sweep voltammetry, rotating ring-disk electrode voltammetry, and the full-cell charge-discharge-cycling test. The discharge peak power density of the Zn-air battery with the unique air electrode reaches 88.8 mW cm-2 at 133.6 mA cm-2 and 0.66 V in an alkaline electrolyte under an ambient atmosphere. After 100 charge-discharge cycles at 10 mA cm-2, an increase of 0.3 V between charge and discharge cell voltages is observed. The deep charge-discharge curve (10 h in each step) indicates that the cell voltages of discharge (1.3 V) and charge (1.97 V) remain constant throughout the process. The performance of the proposed rechargeable Zn-air battery is superior to that of most other similar batteries reported in recent studies.

  14. Mechanish of dTTP Inhibition of the Bifunctional dCTP Deaminase:dUTPase Encoded by Mycobacterium tuberculosis

    DEFF Research Database (Denmark)

    Helt, Signe Smedegaard; Thymark, Majbritt; Harris, Pernille;

    2008-01-01

    Recombinant deoxycytidine triphosphate (dCTP) deaminase from Mycobacterium tuberculosis was produced in Escherichia coli and purified. The enzyme proved to be a bifunctional dCTP deaminase:deoxyuridine triphosphatase. As such, the M. tuberculosis enzyme is the second bifunctional enzyme to be cha...

  15. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Petrie, Jonathan R.; Cooper, Valentino R.; Freeland, John W.; Meyer, Tricia L.; Zhang, Zhiyong; Lutterman, Daniel A.; Lee, Ho Nyung

    2016-03-02

    Strain is known to greatly influence low temperature oxygen electro catalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and Metal-air batteries. However, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals' such as Pt. We attribute the improved bifunctionality to strain induced splitting of the e(g) Orbitals, which can customize orbital asymmetry at the surface. Analogous to strain induced shifts in the d-band center of noble metals relative to the Fermi level, :such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active Oxides.

  16. Nickel sulfide microsphere film on Ni foam as an efficient bifunctional electrocatalyst for overall water splitting.

    Science.gov (United States)

    Zhu, Wenxin; Yue, Xiaoyue; Zhang, Wentao; Yu, Shaoxuan; Zhang, Yuhuan; Wang, Jing; Wang, Jianlong

    2016-01-25

    Developing low-cost, efficient, and bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an appealing yet challenging task. Herein, for the first time, a NiS microsphere film was grown in situ on Ni foam (NiS/Ni foam) via a sulfurization reaction as an efficient bifunctional electrocatalyst for overall water splitting with superior activity and good durability. This NiS/Ni foam electrode delivers 20 mA cm(-2) at an overpotential of 158 mV for the HER and 50 mA cm(-2) at an overpotential of 335 mV for the OER in 1.0 M KOH. This bifunctional electrode also enables a high-efficiency alkaline water electrolyzer with 10 mA cm(-2) at a cell voltage of only 1.64 V, which could be promising in water splitting devices for large-scale hydrogen production. PMID:26661579

  17. Polymer-Supported Reagents: The Role of Bifunctionality in the Design of Ion-Selective Complexants

    Energy Technology Data Exchange (ETDEWEB)

    Alexandratos, S. D.

    2001-06-01

    The importance of multi-functionality in the preparation of ion-selective polymers is evident from the structure of enzymes where specific metal ions are bound through cooperative interactions among different amino acids. In synthetic polymers, ionic selectivity is enhanced when a chemical reaction is superimposed on an ion-exchange process. The concept of reactive ion exchange has been extended through the synthesis of crosslinked polymers whose metal ion selectivity is a function of reduction, coordination or precipitation reactions as determined by various covalently bound ligands. Development of three classes of dual mechanism bifunctional polymers, a new series of bifunctional diphosphonate polymers, and novel bifunctional ion-selective polymers with enhanced ionic accessibility has been accomplished.

  18. Synthesis, characterization and catalytic activity of acid-base bifunctional materials through protection of amino groups

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yanqiu [College of Chemistry, Jilin University, Changchun 130023 (China); College of Chemistry, Mudanjiang Normal University, Mudanjiang 157012 (China); Liu, Heng; Yu, Xiaofang [College of Chemistry, Jilin University, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@mail.jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China)

    2012-03-15

    Graphical abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. Highlights: Black-Right-Pointing-Pointer The acid-base bifunctional material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized through protection of amino groups. Black-Right-Pointing-Pointer The obtained bifunctional material was tested for aldol condensation. Black-Right-Pointing-Pointer The SO{sub 3}H-SBA-15-NH{sub 2} catalyst containing amine and sulfonic acid groups exhibited excellent acid-basic properties. -- Abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. X-ray diffraction (XRD), N{sub 2} adsorption-desorption, transmission electron micrographs (TEM), back titration, {sup 13}C magic-angle spinning (MAS) NMR and {sup 29}Si magic-angle spinning (MAS) NMR were employed to characterize the synthesized materials. The obtained bifunctional material was tested for aldol condensation reaction between acetone and 4-nitrobenzaldehyde. Compared with monofunctional catalysts of SO{sub 3}H-SBA-15 and SBA-15-NH{sub 2}, the bifunctional sample of SO{sub 3}H-SBA-15-NH{sub 2} containing amine and sulfonic acid groups exhibited excellent acid-basic properties, which make it possess high activity for the aldol condensation.

  19. Physical properties of bifunctional BST/LSMO nanocomposites

    International Nuclear Information System (INIS)

    We report the fabrication of bifunctional nanocomposites consisting of ferroelectric Ba0.7Sr0.3TiO3 (BST) and ferromagnetic La0.67Sr0.33MnO3 (LSMO) at different concentrations via a high-temperature solid state route. The structural, dielectric, electrical, magnetodielectric (MD), magnetoelectric (ME) and magnetic properties of BST/LSMO nanocomposites were systematically investigated over a wide range of temperatures and frequencies. The X-Ray Diffraction analyses reveal the nanocrystalline nature of the heterostructures, wherein both perovskite phases co-exist. No parasitic phases were observed. The study of the dielectric properties shows that the nanocomposites exhibit relaxor ferroelectric character, with ferroelectric-paraelectric phase transition temperatures around 287–292 K that do not follow the Curie-Weiss law. The electrical measurements indicate that ac conductivities of the nanocomposites follow the Jonscher's universal power law, with activation energies of 0.42–0.63 eV based on Arrhenius-type behavior at high temperatures. The nanocomposites exhibit well-defined ferromagnetic hysteresis loops at room temperature (RT). The MD and ME measurements at RT indicate that BST/LSMO exhibits a nonlinear ME effect at low frequencies, with a threshold near 0.5 T. The magnetocapacitance (MCp) measurements evidence a quadratic dependence on magnetic field, further confirming the multiferroic nature of BST/LSMO. The order of MCp was found to be ∼7% per Tesla. The analysis of the MCp measurements indicates that one of the BST/LSMO compositions studied can be considered as a new multiferroic compound

  20. Physical properties of bifunctional BST/LSMO nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Beltran-Huarac, Juan, E-mail: baristary26@gmail.com; Morell, Gerardo [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931 (United States); Department of Physics, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico 00936 (United States); Martinez, Ricardo [Department of Mathematics and Physics, University of Puerto Rico, Cayey Campus, Cayey, Puerto Rico 00737 (United States)

    2014-02-28

    We report the fabrication of bifunctional nanocomposites consisting of ferroelectric Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} (BST) and ferromagnetic La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) at different concentrations via a high-temperature solid state route. The structural, dielectric, electrical, magnetodielectric (MD), magnetoelectric (ME) and magnetic properties of BST/LSMO nanocomposites were systematically investigated over a wide range of temperatures and frequencies. The X-Ray Diffraction analyses reveal the nanocrystalline nature of the heterostructures, wherein both perovskite phases co-exist. No parasitic phases were observed. The study of the dielectric properties shows that the nanocomposites exhibit relaxor ferroelectric character, with ferroelectric-paraelectric phase transition temperatures around 287–292 K that do not follow the Curie-Weiss law. The electrical measurements indicate that ac conductivities of the nanocomposites follow the Jonscher's universal power law, with activation energies of 0.42–0.63 eV based on Arrhenius-type behavior at high temperatures. The nanocomposites exhibit well-defined ferromagnetic hysteresis loops at room temperature (RT). The MD and ME measurements at RT indicate that BST/LSMO exhibits a nonlinear ME effect at low frequencies, with a threshold near 0.5 T. The magnetocapacitance (MC{sub p}) measurements evidence a quadratic dependence on magnetic field, further confirming the multiferroic nature of BST/LSMO. The order of MC{sub p} was found to be ∼7% per Tesla. The analysis of the MC{sub p} measurements indicates that one of the BST/LSMO compositions studied can be considered as a new multiferroic compound.

  1. 偶联剂对木塑复合材料拉伸性能与热膨胀性能的影响%Effect of Coupling Agent on Tensile and Thermal Expansion Properties of WPC

    Institute of Scientific and Technical Information of China (English)

    黄润州; 吴清林; 张洋

    2011-01-01

    以高密度聚乙烯( HDPE 6761)为基体,松木(Pine)粉为增强材料,以MAPE(EpoleneG2608)和MAPP(ExxelorVA 1840)为偶联剂采用注塑法制备WPC,测定了不同配比WPC的热膨胀性能与拉伸性能,结果表明:在没有加入MAPE只加入木粉的情况下,WPC的拉伸强度较没有加入任何助剂的HDPE有所下降;偶联剂的加入量按不同配比加入对拉伸模量影响不大;对WPC热膨胀系数主要的影响因素应该是木粉的加入量及塑料基体的种类.%Through injection molding, WPCS were prepared by using HDPE (HDPE 6761) as matrix, pine powder as reinforcer, and MAPE (EpoleneG2608) and MAPP (ExxelorVA1840) and their combinations as coupling agents. And then the thermal and tensile properties of the WPC with different material proportions were measured. Experiment results showed that without addition of modifiers, tensile strength of the composites was lower than that of virgin HDPE. Tensile modulus was not sensitive to content of coupling agent LTEC change of various composites was primarily caused by the matrix and filler content.

  2. Oxidations of amines with molecular oxygen using bifunctional gold–titania catalysts

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Mentzel, Uffe Vie;

    2008-01-01

    Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold–titania c......Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold...

  3. Structural basis for bifunctional peptide recognition at human δ-opioid receptor.

    Science.gov (United States)

    Fenalti, Gustavo; Zatsepin, Nadia A; Betti, Cecilia; Giguere, Patrick; Han, Gye Won; Ishchenko, Andrii; Liu, Wei; Guillemyn, Karel; Zhang, Haitao; James, Daniel; Wang, Dingjie; Weierstall, Uwe; Spence, John C H; Boutet, Sébastien; Messerschmidt, Marc; Williams, Garth J; Gati, Cornelius; Yefanov, Oleksandr M; White, Thomas A; Oberthuer, Dominik; Metz, Markus; Yoon, Chun Hong; Barty, Anton; Chapman, Henry N; Basu, Shibom; Coe, Jesse; Conrad, Chelsie E; Fromme, Raimund; Fromme, Petra; Tourwé, Dirk; Schiller, Peter W; Roth, Bryan L; Ballet, Steven; Katritch, Vsevolod; Stevens, Raymond C; Cherezov, Vadim

    2015-03-01

    Bifunctional μ- and δ-opioid receptor (OR) ligands are potential therapeutic alternatives, with diminished side effects, to alkaloid opiate analgesics. We solved the structure of human δ-OR bound to the bifunctional δ-OR antagonist and μ-OR agonist tetrapeptide H-Dmt-Tic-Phe-Phe-NH2 (DIPP-NH2) by serial femtosecond crystallography, revealing a cis-peptide bond between H-Dmt and Tic. The observed receptor-peptide interactions are critical for understanding of the pharmacological profiles of opioid peptides and for development of improved analgesics. PMID:25686086

  4. A nanostructured bifunctional Pd/C gas-diffusion electrode for metal-air batteries

    OpenAIRE

    McKerracher, R.D.; Alegre, C.; Baglio, V.; Aricò, A.S.; Ponce de León, C.; Mornaghini, F.; Rodlert, M.; Walsh, F. C.

    2015-01-01

    Designing a bifunctional air electrode which catalyses both the oxygen reduction and oxygen evolution reactions is an essential part of progress towards fully rechargeable metal-air batteries, such as the iron-air battery which is environmentally friendly, low cost, and does not suffer risk of thermal runaway like lithium-ion batteries. This paper reports the development of a lightweight carbon-based bifunctional air electrode, catalysed by a small (0.5 mg cm?2) loading of 30 wt.% palladium o...

  5. Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

    DEFF Research Database (Denmark)

    Li, Hu; Khokarale, Santosh Govind; Kotni, Ramakrishna;

    2014-01-01

    A series of acid–base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various...... carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl...

  6. Janus nanobelts: fabrication, structure and enhanced magnetic-fluorescent bifunctional performance

    Science.gov (United States)

    Ma, Qianli; Yu, Wensheng; Dong, Xiangting; Wang, Jinxian; Liu, Guixia

    2014-02-01

    A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts.A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special

  7. Energy Storage in Bifunctional TiO2 Composite Materials under UV and Visible Light

    Directory of Open Access Journals (Sweden)

    Jialin Li

    2009-11-01

    Full Text Available This paper provides an overview of recent studies on energy storage in bifunctional TiO2 composite materials under UV and visible light. The working mechanism, property improvements and applications of these bifunctional TiO2 composite systems are introduced, respectively. The latest results obtained in our laboratory, especially a new process for photoelectric conversion and energy storage in TiO2/Cu2O bilayer films under visible light, are also presented. Hopefully this review will stimulate more fundamental and applied research on this subject in the future.

  8. Simultaneously optimizing fluorescent and paramagnetic properties of bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaofeng; Hu, Shigang [School of Information and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Tan, Congbing [Department of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201 (China); Liu, Yunxin, E-mail: lyunxin@163.com [Department of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201 (China)

    2015-04-15

    Graphical abstract: Crystal field tuning is a powerful approach for simultaneously enhancing the optical and magnetic properties of lanthanide-doped NaGdF{sub 4} bi-functional nanocrystals. - Abstract: Here, we show the simultaneous enhancement of fluorescent and paramagnetic properties in bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning. The energy level splitting calculation indicates, that lanthanide ionic pairs La{sup 3+}/Lu{sup 3+} introduced into the NaGdF{sub 4} host can modify the crystal field around emitters (e.g., Er{sup 3+} and Tm{sup 3+}) and sensitizers (e.g., Yb{sup 3+}) that result in the broadening of crystal field splitting of energy levels and the abundant multi-site distribution of upconversion luminescence. The optimization of the paramagnetic properties in NaGdF{sub 4} doped with emitters and sensitizers is ascribed to the lowering of anti-ferromagnetic coupling.

  9. Biomolecule conjugation strategy using novel water-soluble phosphine-based chelating agents

    Science.gov (United States)

    Katti, Kattesh V.; Gali, Hariprasad; Volkert, Wynn A.

    2004-08-24

    This invention describes a novel strategy to produce phosphine-functionalized biomolecules (e.g. peptides or proteins) for potential use in the design and development of site-specific radiopharmaceuticals for diagnosis or therapy of specific cancers. Hydrophilic alkyl phosphines, in general, tend to be oxidatively unstable. Therefore, incorporation of such phosphine functionalities on peptide (and other biomolecule) backbones, without oxidizing the P.sup.III centers, is difficult. In this context this discovery reports on a new technology by which phosphines, in the form of bifunctional chelating agents, can be directly incorporated on biomolecular backbones using manual synthetic or solid phase peptide synthesis methodologies. The superior ligating abilities of phosphine ligands, with various diagnostically (e.g. TC-99m) or therapeutically (e.g. Re186/188, Rh-105, Au-199) useful radiometals, coupled with the findings that the resulting complexes demonstrate high in vivo stability makes this approach useful in the development of radiolabeled biomolecules for applications in the design of tumor-specific radiopharmaceuticals.

  10. Qualitative screening of veterinary anti-microbial agents in tissues, milk, and eggs of food-producing animals using liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Chen, Dongmei; Yu, Jie; Tao, Yanfei; Pan, Yuanhu; Xie, Shuyu; Huang, Lingli; Peng, Dapeng; Wang, Xu; Wang, Yulian; Liu, Zhenli; Yuan, Zonghui

    2016-04-01

    A method for the analysis of 120 drugs in animal derived food was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These analytes belong to 12 families of veterinary anti-microbial agents (quinolones, macrolides, β-lactams, nitroimidazoles, sulfonamides, lincomycines, chloramphenicols, quinoxalines, tetracyclines, polypeptides, and antibacterial synergists) as well as other compounds not assigned to a particular drug family. The animal derived food samples include muscle and liver of swine, bovine, sheep, and chicken, as well as hen eggs and dairy milk. The sample preparation included ultrasound-assisted extraction (UAE) with acetonitrile-water and a final clean-up with auto solid-phase extraction (SPE) on HLB cartridges. The detection and quantification of 120 anti-microbial agents was performed using LC-MS/MS in positive and negative ion mode. The chromatographic separation was performed on a C18 column using acetonitrile and 0.1% formic acid as the mobile phase. The limit of detection (LOD) and limit of quantification (LOQ) of all drugs in food-producing animals were 0.5-3.0μg/kg and 1.5-10.0μg/kg, respectively. The developed method was successfully utilized to monitor real samples, which demonstrated that it is a simple, fast, and robust method, and could be used as a regulatory to screen for the presence of residues from veterinary anti-microbial drugs in animal-derived foods. PMID:26950031

  11. Bifunctional phage-based pretargeted imaging of human prostate carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Newton-Northup, Jessica R. [Department of Biochemistry, University of Missouri, Columbia, MO 65211 (United States)], E-mail: newtonj@missouri.edu; Figueroa, Said D. [Department of Radiology, University of Missouri, Columbia, MO 65211 (United States); Quinn, Thomas P.; Deutscher, Susan L. [Department of Biochemistry, University of Missouri, Columbia, MO 65211 (United States); Research Service, Harry S. Truman Veterans Memorial Hospital, Columbia, MO 65201 (United States)

    2009-10-15

    Introduction: Two-step and three-step pretargeting systems utilizing biotinylated prostate tumor-homing bacteriophage (phage) and {sup 111}In-radiolabeled streptavidin or biotin were developed for use in cancer radioimaging. The in vivo selected prostate carcinoma-specific phage (G1) displaying up to five copies of the peptide IAGLATPGWSHWLAL was the focus of the present study. Methods: The ability of G1 phage to extravasate and target prostate tumor cells was investigated using immunohistochemistry. G1 phages were biotinylated, streptavidin was conjugated to diethylenetriaminepentaacetic acid (DTPA) and biotin was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Biodistribution studies and single-photon emission computed tomography (SPECT)/CT imaging of xenografted PC-3 tumors via two-step pretargeted {sup 111}In-labeled streptavidin and three-step pretargeted {sup 111}In-labeled biotin were performed in SCID mice to determine the optimal pretargeting method. Results: The ability of G1 phage to extravasate the vasculature and bind directly to human PC-3 prostate carcinoma tumor cells in vivo was demonstrated via immunocytochemical analysis. Comparative biodistribution studies of the two-step and three-step pretargeting strategies indicated increased PC-3 human prostate carcinoma tumor uptake in SCID mice of 4.34{+-}0.26 %ID g{sup -1} at 0.5 h postinjection of {sup 111}In-radiolabeled biotin (utilized in a three-step protocol) compared to 0.67{+-}0.06 %ID g{sup -1} at 24 h postinjection of {sup 111}In radiolabeled streptavidin (employed in a two-step protocol). In vivo SPECT/CT imaging of xenografted PC-3 tumors in SCID mice with the three-step pretargeting method was superior to that of the two-step pretargeting method, and, importantly, blocking studies demonstrated specificity of tumor uptake of {sup 111}In-labeled biotin in the three-step pretargeting scheme. Conclusion: This study demonstrates the use of multivalent bifunctional

  12. Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

    International Nuclear Information System (INIS)

    Graphical abstract: Catalytic conversion of carbohydrates into HMF and EMF in ethanol/DMSO with acid–base bifunctional hybrid nanospheres prepared from self-assembly of corresponding basic amino acids and HPA. - Highlights: • Acid–base bifunctional nanospheres were efficient for production of EMF from sugars. • Synthesis of EMF in a high yield of 76.6% was realized from fructose. • Fructose based biopolymers could also be converted into EMF with good yields. • Ethyl glucopyranoside was produced in good yields from glucose in ethanol. - Abstract: A series of acid–base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity

  13. Synthesis, characterization and use of ATRP bifunctional initiator with trichloromethyl end-groups

    Czech Academy of Sciences Publication Activity Database

    Toman, Luděk; Janata, Miroslav; Spěváček, Jiří; Masař, Bohumil; Vlček, Petr; Látalová, Petra

    2002-01-01

    Roč. 43, č. 2 (2002), s. 18-19. ISSN 0032-3934 R&D Projects: GA ČR GA203/01/0513 Institutional research plan: CEZ:AV0Z4050913 Keywords : bifunctional initiator * ATRP polymerization * trichloromethyl end-groups Subject RIV: CD - Macromolecular Chemistry

  14. Structure and potential applications of amido lanthanide complexes chelated by bifunctional b-diketiminate ligand

    Czech Academy of Sciences Publication Activity Database

    Olejník, R.; Padělková, Z.; Fridrichová, A.; Horáček, Michal; Merna, J.; Růžička, A.

    2014-01-01

    Roč. 759, JUN 2014 (2014), s. 1-10. ISSN 0022-328X R&D Projects: GA ČR GAP106/10/0924 Institutional support: RVO:61388955 Keywords : Bifunctional b-diketiminates * lanthanides * hydroamination Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.173, year: 2014

  15. Asymmetric α-amination of β-keto esters using a guanidine–bisurea bifunctional organocatalyst

    Science.gov (United States)

    Yamamoto, Yoshiharu

    2016-01-01

    Summary An asymmetric α-amination of β-keto esters with azodicarboxylate in the presence of a guanidine–bisurea bifunctional organocatalyst was investigated. The α-amination products were obtained in up to 99% yield with up to 94% ee. PMID:26977179

  16. High surface area carbon for bifunctional air electrodes applied in zinc-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Arai, H. [on leave from NTT Laboratories (Japan); Mueller, S.; Haas, O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Bifunctional air electrodes with high surface area carbon substrates showed low reduction overpotential, thus are promising for enhancing the energy efficiency and power capability of zinc-air batteries. The improved performance is attributed to lower overpotential due to diffusion of the reaction intermediate, namely the peroxide ion. (author) 1 fig., 2 refs.

  17. Bifunctional catalysts for the direct production of liquid fuels from syngas

    NARCIS (Netherlands)

    Sartipi, S.

    2014-01-01

    Design and development of catalyst formulations that maximize the direct production of liquid fuels by combining Fischer-Tropsch synthesis (FTS), hydrocarbon cracking, and isomerization into one single catalyst particle (bifunctional FTS catalyst) have been investigated in this thesis. To achieve th

  18. Comparison of the oncogenic potential of several chemotherapeutic agents

    International Nuclear Information System (INIS)

    Several chemotherapeutic drugs that have been routinely used in cancer treatment were tested for their carcinogenic potential. Two antitumor antibiotics (adriamycin and vincristine), an alkalating agent (melphalan), 5-azacytidine and the bifunctional agent cis-platinum that mimics alkylating agents and/or binds Oxygen-6 or Nitrogen-7 atoms of quanine were tested. Cell killing and cancer induction was assessed using in vitro transformation system. C3H/10T 1/2 cells, while normally exhibiting contact inhibition, can undergo transformation from normal contact inhibited cells to tumorgenic cells when exposed to chemical carcinogens. These cells have been used in the past by this laboratory to study oncogenic transformation of cells exposed to ionizing radiation and electron affinic compounds that sensitize hypoxic cells to x-rays. The endpoints of cell killing and oncogenic transformation presented here give an estimate of the carcinogenic potential of these agents

  19. Agent engineering

    CERN Document Server

    Liu, Jiming; Zhong, Ning; Wang, Patrick S P

    2001-01-01

    Agent engineering concerns the development of autonomous computational or physical entities capable of perceiving, reasoning, adapting, learning, cooperating and delegating in a dynamic environment. It is one of the most promising areas of research and development in information technology, computer science and engineering. This book addresses some of the key issues in agent engineering: What is meant by "autonomous agents"? How can we build agents with autonomy? What are the desirable capabilities of agents with respect to surviving (they will not die) and living (they will furthermore enjoy

  20. Antibiotic Agents

    Science.gov (United States)

    ... either as public health or as non-public health antimicrobial agents. What is the difference between bacteriostats, sanitizers, disinfectants ... bacteria, however, there is considerable controversy surrounding their health benefits. The ... producing agents (Table of Antibacterials) have been used for many ...

  1. Bifunctional Nb/Ti-MCM-41 catalyst in oxidative acidic reaction of cyclohexene to diol

    International Nuclear Information System (INIS)

    Bifunctional oxidative and acidic catalyst was prepared by incorporating titanium ion (Ti4+) and niobic acid in meso porous molecular sieves MCM-41 structure. The catalyst is active both in oxidation, and acid-catalyzed reaction of olefin to diol. Nb/ Ti-MCM-41 catalyst was prepared by first synthesizing Ti-MCM-41 by hydrothermal method, followed by subsequent impregnation of niobic acid (Nb) into Ti-MCM-41 at various % wt Nb loading. The framework structure of Ti-MCM-41 collapsed after incorporation of Nb but the tetrahedral form of Ti4+ still maintained with octahedral Nb species. Both Bronsted and Lewis acid sites are present in all Nb/ Ti-MCM-41 samples. The formation of cyclohexanediol in the epoxidation of cyclohexene proved the bifunctional oxidative and acidic catalyst through the formation of cyclohexane oxide. The yield increased with the increase amount of the Bronsted acid sites provided by niobium species. (author)

  2. Tethering metal ions to photocatalyst particulate surfaces by bifunctional molecular linkers for efficient hydrogen evolution

    KAUST Repository

    Yu, Weili

    2014-08-19

    A simple and versatile method for the preparation of photocatalyst particulates modified with effective cocatalysts is presented; the method involves the sequential soaking of photocatalyst particulates in solutions containing bifunctional organic linkers and metal ions. The modification of the particulate surfaces is a universal and reproducible method because the molecular linkers utilize strong covalent bonds, which in turn result in modified monolayer with a small but controlled quantity of metals. The photocatalysis results indicated that the CdS with likely photochemically reduced Pd and Ni, which were initially immobilized via ethanedithiol (EDT) as a linker, were highly efficient for photocatalytic hydrogen evolution from Na2S-Na2SO3-containing aqueous solutions. The method developed in this study opens a new synthesis route for the preparation of effective photocatalysts with various combinations of bifunctional linkers, metals, and photocatalyst particulate materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    information that is inaccessible by purely experimental means, and these structures, in turn, strongly suggest that a bifunctional reaction mechanism for alkaline HER will be operative at the interface between the films, the metal substrates, and the surrounding aqueous medium. This bifunctionality produces...... under alkaline electrochemical conditions. We demonstrate that the structure and oxidation state of the films can be systematically tuned by changing the applied electrode potential and/or the nature of substrates. Structural features determined from the theoretical calculations provide a wealth of...... important changes in the calculated barriers of key elementary reaction steps, including water activation and dissociation, as compared to traditional monofunctional Pt surfaces. The successful identification of the structures of thin metal films and three-phase boundary catalysts is not only an important...

  4. Synthesis and biological evaluation of 177Lu-DOTA-porphyrin conjugate: a potential agent for targeted tumor radiotherapy

    International Nuclear Information System (INIS)

    A novel unsymmetrically substituted water soluble porphyrin derivative namely, 5-(p-aminopropylene-oxyphenyl)-10,15,20-tris-(p-carboxymetylene-oxyphenyl) porphyrin was synthesized and coupled with a bifunctional chelating agent, viz. p-NCS-benzyl-DOTA (p-isothiocyanatobenzyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) for developing a suitable conjugate for use in targeted tumor therapy. The porphyrin-p-NCS-benzyl-DOTA conjugate was radiolabeled with 177Lu in good radiolabeling yield. Biodistribution studies performed in Swiss mice bearing fibrosarcoma tumors revealed high tumor uptake (5.33±1.11% injected activity per gm of tumor) within 30 min post-injection. The complex exhibited favorable tumor to blood and tumor to muscle ratios at various post-administration time points. Fast clearance of the non-accumulated activity was observed mostly through the renal pathway. Scintigraphic imaging studies performed in Swiss mice bearing fibrosarcoma tumors also exhibited selective accumulation of activity in the tumor.

  5. Radiation Induced Crosslinking of Polyethylene in the Presence of Bifunctional Vinyl Monomers

    DEFF Research Database (Denmark)

    Joshi, M. S.; Singer, Klaus Albert Julius; Silverman, J.

    Several reports have been published showing that the radiation induced grafting of bifunctional vinyl monomers to low density polyethylene results in a product with an unusually high density of crosslinks. The same grafting reactions are shown to reduce the incipient gel dose by more than a factor...... of fifty. This paper is concerned with the apparent crosslinking produced by the radiation grafting of two monomers to polyethylene: acrylic acid and acrylonitrile....

  6. Bifunctional silica nanoparticles for the exploration of biofilms of Pseudomonas aeruginosa

    OpenAIRE

    Mauline, Léïla; Gressier, Marie; Roques, Christine; Hammer, Peter,; Ribeiro, Sidney J. L.; Caiut, José Maurício A.; Menu, Marie-Joëlle

    2013-01-01

    Luminescent silica nanoparticles are frequently employed for biotechnology applications mainly because of their easy functionalization, photo-stability, and biocompatibility. Bifunctional silica nanoparticles (BSNPs) are described here as new efficient tools for investigating complex biological systems such as biofilms. Photoluminescence is brought about by the incorporation of a silylated ruthenium (II) complex. The surface properties of the silica particles were designed by reaction with am...

  7. L-Proline Derived Bifunctional Organocatalysts: Enantioselective Michael Addition of Dithiomalonates to trans-β-Nitroolefins.

    Science.gov (United States)

    Jin, Hui; Kim, Seung Tae; Hwang, Geum-Sook; Ryu, Do Hyun

    2016-04-15

    A series of novel L-proline derived tertiary amine bifunctional organocatalysts 9 are reported, which were applied to the asymmetric Michael addition of dithiomalonates 2 to trans-β-nitroolefins 1. The reaction proceeded in high yields (up to 99%) with high enantioselectivities (up to 97% ee). The synthetic utility of this methodology was demonstrated in the short synthesis of (R)-phenibut in high yield. PMID:26989804

  8. GST-TAT-SOD: Cell Permeable Bifunctional Antioxidant Enzyme—A Potential Selective Radioprotector

    OpenAIRE

    Jianru Pan; Huocong He; Ying Su; Guangjin Zheng; Junxin Wu; Shutao Liu; Pingfan Rao

    2016-01-01

    Superoxide dismutase (SOD) fusion of TAT was proved to be radioprotective in our previous work. On that basis, a bifunctional recombinant protein which was the fusion of glutathione S-transferase (GST), SOD, and TAT was constructed and named GST-TAT-SOD. Herein we report the investigation of the cytotoxicity, cell-penetrating activity, and in vitro radioprotective effect of GST-TAT-SOD compared with wild SOD, single-function recombinant protein SOD-TAT, and amifostine. We demonstrated that wi...

  9. 3D Ordered Mesoporous Bifunctional Oxygen Catalyst for Electrically Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Park, Moon Gyu; Lee, Dong Un; Seo, Min Ho; Cano, Zachary Paul; Chen, Zhongwei

    2016-05-01

    To enhance energy efficiency and durability, a highly active and durable 3D ordered mesoporous cobalt oxide framework has been developed for rechargeable zinc-air batteries. The bifunctional air electrode consisting of 3DOM Co3 O4 having high active surface area and robust structure, results in superior charge and discharge battery voltages, and durable performance for electrically rechargeable zinc-air batteries. PMID:27043451

  10. Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Zou, Yongcun [State Key Laboratory of Inoranic Synthesis and Preparative Chemistryg, College of Chemistry, Jilin University, Changchun 130012 (China); Wu, Shujie; Liu, Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

    2011-06-15

    Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO{sub 3}H-MCM-41-NH{sub 2} containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: {yields} Synthesize acid-base bifunctional mesoporous materials SO{sub 3}H-MCM-41-NH{sub 2}. {yields} Oxidation and then thermolysis to generate acidic site and basic site. {yields} Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO{sub 3}H-MCM-41-NH{sub 2}. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state {sup 13}C CP/MAS NMR and solid-state {sup 29}Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO{sub 3}H-MCM-41-NH{sub 2}) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

  11. Bifunctional catalysts for the direct production of liquid fuels from syngas

    OpenAIRE

    Sartipi, S.

    2014-01-01

    Design and development of catalyst formulations that maximize the direct production of liquid fuels by combining Fischer-Tropsch synthesis (FTS), hydrocarbon cracking, and isomerization into one single catalyst particle (bifunctional FTS catalyst) have been investigated in this thesis. To achieve this aim, a second functionality (other than FTS) has to be added to the catalyst formulation to break the limitation of a classical Anderson-Schulz-Flory (ASF) distribution of FTS products. Since up...

  12. Radiation Induced Crosslinking of Polyethylene in the Presence of Bifunctional Vinyl Monomers

    DEFF Research Database (Denmark)

    Joshi, M. S.; Singer, Klaus Albert Julius; Silverman, J.

    Several reports have been published showing that the radiation induced grafting of bifunctional vinyl monomers to low density polyethylene results in a product with an unusually high density of crosslinks. The same grafting reactions are shown to reduce the incipient gel dose by more than a facto...... of fifty. This paper is concerned with the apparent crosslinking produced by the radiation grafting of two monomers to polyethylene: acrylic acid and acrylonitrile....

  13. Bifunctional Metamaterials with Simultaneous and Independent Manipulation of Thermal and Electric Fields

    OpenAIRE

    Lan, Chuwen; Li, Bo; Zhou, Ji

    2015-01-01

    Metamaterials offer a powerful way to manipulate a variety of physical fields ranging from wave fields (electromagnetic field, acoustic field, elastic wave, etc.), static fields (static magnetic field, static electric field) to diffusive fields (thermal field, diffusive mass). However, the relevant reports and studies are usually conducted on a single physical field or functionality. In this study, we proposed and experimentally demonstrated a bifunctional metamaterial which can manipulate th...

  14. Effect of Coupling Agent and its Hydrolysis on Tensile Properties of Epoxy Resin%硅烷偶联剂及其水解物对环氧树脂拉伸剪切强度的影响

    Institute of Scientific and Technical Information of China (English)

    吕澍; 宋建华

    2012-01-01

    以双酚A和环氧氯丙烷为原料,通过缩聚反应制得环氧树脂;将硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH- 570)在酸催化下水解,得到水解物.探讨了KH -570及其水解物用量对环氧树脂胶黏剂拉伸剪切强度的影响.结果表明,不加KH - 570及其水解物时,环氧树脂胶黏剂的拉伸剪切强度最大为2.47 MPa;只加KH - 570水解物时,环氧树脂胶黏剂的拉伸剪切强度最大为3.28 MPa;只加入KH - 570时,环氧树脂胶黏剂的拉伸剪切强度最大为5.23 MPa.在KH - 570水解物与环氧树脂的质量比相同条件下,随着KH - 570用量的增大,环氧树脂胶黏剂的剪切强度先增后减,在KH - 570的用量为环氧树脂质量的15%时达到最大;相同KH - 570用量下,随着KH - 570水解物用量的增大,环氧树脂胶黏剂的剪切强度先增后减,在KH - 570水解物和环氧树脂的质量比为5∶5时达到最大.当KH - 570的用量为环氧树脂质量的15%、KH - 570水解物与环氧树脂的质量比为5∶5时,环氧树脂胶黏剂的拉伸剪切强度达到9.36 MPa.%Epoxy resin was prepared by the reaction of bisphenol-A and epichlorohydrin by condensation polymerization. The effect of the different contents of silicone coupling agent y - methacryloxypropyltrimethox-ysilane ( KH - 570 ) and its hydrolysis under acidic condition on the tensile properties of the epoxy resin adhesive was studied. Result showed that the maximum tensile shear force of the epoxy resin adhesive was 2. 47 MPa without KH - 570 and its hydrolysis, while the maximum tensile shear forces of the epoxy resin adhesive in the presence of only KH -570 hydrolyzate and only KH -570 were 3. 28 MPa and 5. 23 MPa, respectively, suggesting that the tensile properties of the epoxy resin adhesive were improved by adding silicone coupling a-gent KH -570 and its hydrolysis content. As KH -570 content reached 15% , the tensile capacity was optimum. When the ratio of the hydrolysis

  15. New approach to immunochemical determinations for triclopyr and 3,5,6-trichloro-2-pyridinol by using a bifunctional hapten, and evaluation of polyclonal antiserum.

    Science.gov (United States)

    Watanabe, Eiki; Hoshino, Ryoko; Kanzaki, Yukiko; Tokumoto, Hiroshi; Kubo, Hiroaki; Nakazawa, Hiroyuki

    2002-06-19

    The present work describes the design and synthesis of the structurally unique hapten, "bifunctional hapten", to produce a group-specific polyclonal antiserum to triclopyr and 3,5,6-trichloro-2-pyridinol. A bifunctional hapten was designed and synthesized by conjugating commercially available Nepsilon-2,4-dinitrophenyl (DNP)-L-lysine to triclopyr, and then coupling this to carrier proteins such as bovine serum albumin (BSA). The synthesized bifunctional hapten greatly raised the antiserum titer in comparison with that of the conventional hapten, triclopyr. Antiserum with a sufficiently high titer to provide the determinations of targeted compounds was obtained only 63 days after the primary immunization. The obtained antiserum showed the highest affinity to triclopyr (IC(50) = 3.5 nM) and 3,5,6-trichloro-2-pyridinol (IC(50) = 5.1 nM) in homologous ELISA. The cross-reactivities to various agrochemicals and some chlorinated phenolic compounds were determined. Significant cross-reactivity was found to the herbicide 2,4,5-T. The antiserum reacted to both triclopyr and its metabolite. Assay sensitivity was evaluated for effects of various assay conditions, including pH value and concentrations of organic solvents and detergents. Under optimized assay conditions, the quantitative working range of triclopyr ELISA was from 0.1 to 5.2 ng/mL with a limit of detection (LOD) of 0.037 ng/mL, and an IC(50) of 0.72 ng/mL. On the other hand, the quantitative working range of 3,5,6-trichloro-2-pyridinol ELISA was from 0.13 to 6.0 ng/mL with a LOD of 0.052 ng/mL, and an IC(50) of 0.95 ng/mL. Water samples fortified with triclopyr or its metabolite at 1, 5, and 10 ng/mL were directly analyzed without extraction and cleanup by the proposed ELISA. The mean recovery was 101.6%, and the mean coefficient of variation (CV) was 7.1% in the case of the triclopyr ELISA. In the case of the 3,5,6-trichloro-2-pyridinol ELISA, the mean recovery was 99.8%, and the mean CV was 9.5%. The proposed

  16. Bifunctional Catalysts for Upgrading of Biomass-Derived Oxygenates: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Allison M.; Hensley, Jesse E.; Medlin, J. Will

    2016-08-05

    Deoxygenation is an important reaction in the conversion of biomass-derived oxygenates to fuels and chemicals. A key route for biomass refining involves the production of pyrolysis oil through rapid heating of the raw biomass feedstock. Pyrolysis oil as produced is highly oxygenated, so the feasibility of this approach depends in large part on the ability to selectively deoxygenate pyrolysis oil components to create a stream of high-value finished products. Identification of catalytic materials that are active and selective for deoxygenation of pyrolysis oil components has therefore represented a major research area. One catalyst is rarely capable of performing the different types of elementary reaction steps required to deoxygenate biomass-derived compounds. For this reason, considerable attention has been placed on bifunctional catalysts, where two different active materials are used to provide catalytic sites for diverse reaction steps. Here, we review recent trends in the development of catalysts, with a focus on catalysts for which a bifunctional effect has been proposed. We summarize recent studies of hydrodeoxygenation (HDO) of pyrolysis oil and model compounds for a range of materials, including supported metal and bimetallic catalysts as well as transition-metal oxides, sulfides, carbides, nitrides, and phosphides. Particular emphasis is placed on how catalyst structure can be related to performance via molecular-level mechanisms. These studies demonstrate the importance of catalyst bifunctionality, with each class of materials requiring hydrogenation and C-O scission sites to perform HDO at reasonable rates.

  17. Comparison of Dynamical Behaviors Between Monofunctional and Bifunctional Two-Component Signaling Modules

    Science.gov (United States)

    Yang, Xiyan; Wu, Yahao; Yuan, Zhanjiang

    2015-06-01

    Two-component signaling modules exist extensively in bacteria and microbes. These modules can be, based on their distinct network structures, divided into two types: the monofunctional system (denoted by MFS) where the sensor kinase (SK) modulates only phosphorylation of the response regulator (RR), and the bifunctional system (denoted by BFS) where the SK catalyzes both phosphorylation and dephosphorylation of the RR. Here, we analyze dynamical behaviors of these two systems based on stability theory, focusing on differences between them. The analysis of the deterministic behavior indicates that there is no difference between the two modules, that is, each system has the unique stable steady state. However, there are significant differences in stochastic behavior between them. Specifically, if the mean phosphorylated SK level is kept the same for the two modules, then the variance and the Fano factor for the phosphorylated RR in the BFS are always no less than those in the MFS, indicating that bifunctionality always enhances fluctuations. The correlation between the phosphorylated SK and the phosphorylated RR in the BFS is always positive mainly due to competition between system components, but this correlation in the MFS may be positive, almost zero, or negative, depending on the ratio between two rate constants. Our overall analysis indicates that differences between dynamical behaviors of monofunctional and bifunctional signaling modules are mainly in the stochastic rather than deterministic aspect.

  18. Collagen/chitosan based two-compartment and bi-functional dermal scaffolds for skin regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng [Department of Plastic Surgery and Burns, Shenzhen Second People' s Hospital, Shenzhen 518035 (China); Wang, Mingbo [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); She, Zhending [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shenzhen Lando Biomaterials Co., Ltd., Shenzhen 518057 (China); Fan, Kunwu; Xu, Cheng [Department of Plastic Surgery and Burns, Shenzhen Second People' s Hospital, Shenzhen 518035 (China); Chu, Bin; Chen, Changsheng [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shi, Shengjun, E-mail: shengjunshi@yahoo.com [The Burns Department of Zhujiang Hospital, Southern Medical University, Guangzhou 510280 (China); Tan, Rongwei, E-mail: tanrw@landobiom.com [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shenzhen Lando Biomaterials Co., Ltd., Shenzhen 518057 (China)

    2015-07-01

    Inspired from the sophisticated bilayer structures of natural dermis, here, we reported collagen/chitosan based two-compartment and bi-functional dermal scaffolds. Two functions refer to mediating rapid angiogenesis based on recombinant human vascular endothelial growth factor (rhVEGF) and antibacterial from gentamicin, which were encapsulated in PLGA microspheres. The gentamicin and rhVEGF encapsulated PLGA microspheres were further combined with collagen/chitosan mixtures in low (lower layer) and high (upper layer) concentrations, and molded to generate the two-compartment and bi-functional scaffolds. Based on morphology and pore structure analyses, it was found that the scaffold has a distinct double layered porous and connective structure with PLGA microspheres encapsulated. Statistical analysis indicated that the pores in the upper layer and in the lower layer have great variations in diameter, indicative of a two-compartment structure. The release profiles of gentamicin and rhVEGF exceeded 28 and 49 days, respectively. In vitro culture of mouse fibroblasts showed that the scaffold can facilitate cell adhesion and proliferation. Moreover, the scaffold can obviously inhibit proliferation of Staphylococcus aureus and Serratia marcescens, exhibiting its unique antibacterial effect. The two-compartment and bi-functional dermal scaffolds can be a promising candidate for skin regeneration. - Highlights: • The dermal scaffold is inspired from the bilayer structures of natural dermis. • The dermal scaffold has two-compartment structures. • The dermal scaffold containing VEGF and gentamicin encapsulated PLGA microspheres • The dermal scaffold can facilitate cell adhesion and proliferation.

  19. Bifunctional Perovskite Oxide Catalysts for Oxygen Reduction and Evolution in Alkaline Media.

    Science.gov (United States)

    Gupta, Shiva; Kellogg, William; Xu, Hui; Liu, Xien; Cho, Jaephil; Wu, Gang

    2016-01-01

    Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bifunctional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media and review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in the recent literature. We also summarize the present strategies to modify their electronic structure and to further improve their performance for the ORR/OER through highlighting the new concepts relating to the role of surface redox chemistry and oxygen deficiency of perovskite oxides for the ORR/OER activity. In addition, we provide a brief account of recently developed advanced perovskite-nanocarbon hybrid bifunctional catalysts with much improved performances. PMID:26247625

  20. Collagen/chitosan based two-compartment and bi-functional dermal scaffolds for skin regeneration

    International Nuclear Information System (INIS)

    Inspired from the sophisticated bilayer structures of natural dermis, here, we reported collagen/chitosan based two-compartment and bi-functional dermal scaffolds. Two functions refer to mediating rapid angiogenesis based on recombinant human vascular endothelial growth factor (rhVEGF) and antibacterial from gentamicin, which were encapsulated in PLGA microspheres. The gentamicin and rhVEGF encapsulated PLGA microspheres were further combined with collagen/chitosan mixtures in low (lower layer) and high (upper layer) concentrations, and molded to generate the two-compartment and bi-functional scaffolds. Based on morphology and pore structure analyses, it was found that the scaffold has a distinct double layered porous and connective structure with PLGA microspheres encapsulated. Statistical analysis indicated that the pores in the upper layer and in the lower layer have great variations in diameter, indicative of a two-compartment structure. The release profiles of gentamicin and rhVEGF exceeded 28 and 49 days, respectively. In vitro culture of mouse fibroblasts showed that the scaffold can facilitate cell adhesion and proliferation. Moreover, the scaffold can obviously inhibit proliferation of Staphylococcus aureus and Serratia marcescens, exhibiting its unique antibacterial effect. The two-compartment and bi-functional dermal scaffolds can be a promising candidate for skin regeneration. - Highlights: • The dermal scaffold is inspired from the bilayer structures of natural dermis. • The dermal scaffold has two-compartment structures. • The dermal scaffold containing VEGF and gentamicin encapsulated PLGA microspheres • The dermal scaffold can facilitate cell adhesion and proliferation

  1. 钛酸酯对电气石粉体的表面改性及表征%Surface Modification and Characterization of Tourmaline Powder by Titanate Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    胡应模; 杨雪; 王清岭; 边静

    2013-01-01

    以沉降时间、吸油值、吸光度等为评价参数,优化了钛酸酯偶联剂对电气石粉体表面有机化改性的工艺条件.确定以蒸馏水作溶剂,钛酸酯的用量为电气石质量的4%,反应体系pH值为9,矿浆固液比为10∶50,60℃下反应1.0h,所得改性电气石在液体石蜡中的沉降时间由原电气石的14min延长到467min;电气石表面的有机改性只降低了电气石表面的极性,而不改变电气石的晶体结构,且改性电气石的负离子释放量增加为未改性电气石的1.75倍.%The surface organic modification of tourmaline powder with titanate coupling agent was studied in detail with the parameters of settling time, oil absorption value and absorbance, and the optimal technological conditions were determined as 4% (of the mass of tourmaline powder)of titanate coupling agent with the solid/liquid ratio 10: 50 of the ore slurry reacted at 60℃ for 1.0h in distilled water of pH9 ,and the settling time of modified tourmaline increased to 467min from 14min of raw tourmaline in liquid paraffin. The characterization of structure showed that surface organic modification has only reduced the surface polarity of tourmaline,but not altered the crystal structure of tourmaline, and the amount of released negative ions of modified tourmaline was 1.75 times of raw tourmaline.

  2. 新型可聚合硼酸酯偶联剂的合成及应用研究%Synthesis and Properties of Novel Borate Ester Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    席娟; 于泽鑫; 王鹤霏; 张勇; 李安东

    2012-01-01

    Boric acid and diethanolamine intermediates were used to synthesize a boric acid diethanolamine ester Ⅰ.With maleic anhydride acylation,it occurred acylation in the N,N-Dimethylformamide solvent.It synthesized boric acid esters Ⅱ containing a polymerizable double bonds.Within a single molecule into boron nitride,as well as carboxyl,unsaturated double bond,amide bond and other active groups,a good coupling agent application performance could be achieved.Boric acid ester polymer was used in PA-6/square-shaped zinc oxide(T-ZnO) whisker system.Mechanical properties have greatly improved.From the SEM of the impact fracture surface of the spline,the conclusions were gained that zinc oxide whisker,which was surface treated by Ⅱ,was found and a part of the whisker was coated by the matrix resin.And the better interface layer which was formed between the whisker and the matrix played a good role in the effect of coupling agent.%以硼酸和二乙醇胺为原料合成中间体硼酸二乙醇胺酯,将其与马来酸酐在N,N-二甲基甲酰胺溶剂中发生酰化反应,合成含有可聚合双键的硼酸酯.在同一个分子内引入硼氮两元素,以及羧基、不饱和双键、酰胺键等活性基团,以达到良好的偶联剂应用性能.将可聚合硼酸酯应用于PA-6/四角状氧化锌(T-ZnO)晶须体系中,力学性能显著提高,从样条冲击断面的扫描电镜中可以看出,氧化锌晶须经过可聚合硼酸酯表面处理后,部分晶须被基体树脂包覆,晶须与基体间形成了良好的界面层,很好的起到了偶联剂的效果.

  3. Simple and general procedure for the synthesis of semi-rigid chelating agents for radiometal complexation studies and its application to semi-rigid functionalised ligands (BCA) synthesis

    International Nuclear Information System (INIS)

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine-131 may not be the best isotope for tumour therapy because of its limited specific activity, low beta-energy, relatively long half-life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelators that can hold radiometals with high stability under physiological conditions are essential to avoid excessive radiation damage to non-target cells. Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. The stability of a non-macrocyclic ligand can be favourably influenced by the preorganization of the open chain. In fact, a semi-rigid structure such as that of trans-1,2-diaminocyclohexane limits the rotation of the ethylene bridge, so that the purpose of the cyclohexane design is to preorient the four pendent arms in a skew position. Therefore, we have developed a new simple and efficient synthesis pathway from trans-1,2-diaminocyclohexane to provide access to a new class of semi-rigid chelating agents. This same reactional scheme will be apply to our reactional intermediary, (1R*, 2R*, 4S*)-4-acetamido-1,2-diaminocyclohexane dihydrochloride, which will allow the synthesis of these same chelating agents, though functionalised back of the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (orig.)

  4. Trypanosoma brucei DHFR-TS Revisited: Characterisation of a Bifunctional and Highly Unstable Recombinant Dihydrofolate Reductase-Thymidylate Synthase.

    Science.gov (United States)

    Gibson, Marc W; Dewar, Simon; Ong, Han B; Sienkiewicz, Natasha; Fairlamb, Alan H

    2016-05-01

    Bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) is a chemically and genetically validated target in African trypanosomes, causative agents of sleeping sickness in humans and nagana in cattle. Here we report the kinetic properties and sensitivity of recombinant enzyme to a range of lipophilic and classical antifolate drugs. The purified recombinant enzyme, expressed as a fusion protein with elongation factor Ts (Tsf) in ThyA- Escherichia coli, retains DHFR activity, but lacks any TS activity. TS activity was found to be extremely unstable (half-life of 28 s) following desalting of clarified bacterial lysates to remove small molecules. Stability could be improved 700-fold by inclusion of dUMP, but not by other pyrimidine or purine (deoxy)-nucleosides or nucleotides. Inclusion of dUMP during purification proved insufficient to prevent inactivation during the purification procedure. Methotrexate and trimetrexate were the most potent inhibitors of DHFR (Ki 0.1 and 0.6 nM, respectively) and FdUMP and nolatrexed of TS (Ki 14 and 39 nM, respectively). All inhibitors showed a marked drop-off in potency of 100- to 1,000-fold against trypanosomes grown in low folate medium lacking thymidine. The most potent inhibitors possessed a terminal glutamate moiety suggesting that transport or subsequent retention by polyglutamylation was important for biological activity. Supplementation of culture medium with folate markedly antagonised the potency of these folate-like inhibitors, as did thymidine in the case of the TS inhibitors raltitrexed and pemetrexed. PMID:27175479

  5. Nanocompósitos de polietileno/argila bentonita nacional: influência da argila e do agente compatibilizante PE-g-MA nas propriedades mecânicas e de inflamabilidade Polyethylene/national bentonite clay nanocomposites: influence of clay and PE-g-MA coupling agent on the mechanical properties and flammability

    Directory of Open Access Journals (Sweden)

    Gustavo F. Brito

    2008-06-01

    Full Text Available Nanocompósitos de polietileno de alta densidade/argila bentonita nacional foram preparados por intercalação por fusão. A influência da adição da argila sem tratamento e da argila tratada com o sal quaternário de amônio Cetremide e do polietileno graftizado com anidrido maléico (PE-g-MA como agente compatibilizante foi avaliada. Os sistemas obtidos foram caracterizados por inflamabilidade, propriedades mecânicas e reológicas, difração de raios X e microscopia eletrônica de transmissão. Os resultados de difração de raios X e microscopia eletrônica de transmissão indicaram a obtenção de nanocompósitos com estruturas parcialmente esfoliadas e/ou intercaladas que conduziram ao aumento do módulo de elasticidade e do valor do torque. O teste de inflamabilidade mostrou que a adição da argila na matriz polimérica e a presença do PE-g-MA retardaram a velocidade de queima do sistema, ou seja, diminuíram a inflamabilidade do PE puro. Em geral, o sistema contendo o agente compatibilizante (PE-g-MA exibiu melhorias na estabilidade térmica e nanocompósitos parcialmente esfoliados foram formados, quando comparados à matriz de polietileno de alta densidade. O polietileno graftizado com anidrido maléico não apenas promoveu a esfoliação da argila, mas também facilitou a adesão carga-matriz, obtendo-se com isso melhorias nos resultados mecânicos do sistema.High density polyethylene/national bentonite clay nanocomposites were prepared with the melt intercalation technique. The effect of the clay without treatment and clay treated with quaternary ammonium salt Cetremide with polyethylene-graft-maleic anhydride as coupling agent was evaluated. The systems were characterized by flammability, mechanical and rheological properties, X ray diffraction and transmission electron microscopy. In general, the results of X ray diffraction and transmission electron microscopy showed partially exfoliated and/or intercalated structures with

  6. Preparation and characteristics of Fe3O4-YVO4:Eu3+ bifunctional magnetic-luminescent nanocomposites

    International Nuclear Information System (INIS)

    Graphical abstract: Highlights: → Bifunctional magnetic-luminescent nanocomposites with Fe3O4 nanoparticles as the core and YVO4:Eu3+ as the shell. → A cubic spinel structrue of Fe3O4 core and a tetragonal phase of YVO4 shell were obtained. → The nanocomposites displayed a strong red emission and superparamagnetic behavior at room temperature. - Abstract: A facile direct precipitation method has been developed for the synthesis of bifunctional magnetic-luminescent nanocomposites with Fe3O4 nanoparticles as the core and YVO4:Eu3+ as the shell. Transmission electron microscopy (TEM) images revealed that the obtained bifunctional nanocomposites had a core-shell structure and a spherical morphology. The average size was ∼150 nm, and the thickness of the shell was ∼15 nm. The X-ray diffraction (XRD) patterns showed that a cubic spinel structure of Fe3O4 core and a tetragonal phase of YVO4 shell were obtained. Fourier transform infrared (FT-IR) spectra confirmed that the YVO4:Eu3+ had been successfully deposited on the surface of Fe3O4 nanoparticles. Photoluminescence (PL) spectra indicated that the nanocomposites displayed a strong red characteristic emission of Eu3+. Magnetic measurements showed that the obtained bifunctional nanocomposites exhibited superparamagnetic behavior at room temperature. Therefore, the bifunctional nanocomposites are expected to develop many potential applications in biomedical fields.

  7. Rh(III)-Catalyzed C-C/C-N Coupling of Imidates with α-Diazo Imidamide: Synthesis of Isoquinoline-Fused Indoles.

    Science.gov (United States)

    Wang, He; Li, Lei; Yu, Songjie; Li, Yunyun; Li, Xingwei

    2016-06-17

    Imidate esters and diazo compounds have been established as bifunctional substrates for the construction of biologically active fused heterocycles via rhodium-catalyzed C-H activation and C-C/C-N coupling. This reaction occurs under mild conditions with high efficiency, step economy, and low catalyst loading. PMID:27280947

  8. Agent, autonomous

    OpenAIRE

    Luciani, Annie

    2007-01-01

    The expression autonomous agents, widely used in virtual reality, computer graphics, artificial intelligence and artificial life, corresponds to the simulation of autonomous creatures, virtual (i.e. totally computed by a program), or embodied in a physical envelope, as done in autonomous robots.

  9. Nanostructured Perovskite LaCo1-xMnxO3 as Bifunctional Catalysts for Rechargeable Metal-Air Batteries

    Science.gov (United States)

    Ge, Xiaoming; Li, Bing; Wuu, Delvin; Sumboja, Afriyanti; An, Tao; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2015-09-01

    Bifunctional catalyst that is active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most important components of rechargeable metal-air batteries. Nanostructured perovskite bifunctional catalysts comprising La, Co and Mn(LaCo1-xMnxO3, LCMO) are synthesized by hydrothermal methods. The morphology, structure and electrochemical activity of the perovskite bifunctional catalysts are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) techniques. Nanorod, nanodisc and nanoparticle are typical morphologies of LCMO. The electrocatalytic activity of LCMO is significantly improved by the addition of conductive materials such as carbon nanotube. To demonstrate the practical utilization, LCMO in the composition of LaCo0.8Mn0.2O3(LCMO82) is used as air cathode catalysts for rechargeable zinc-air batteries. The battery prototype can sustain 470 h or 40 discharge-charge cycles equivalent.

  10. In vivo evaluation of a radiogallium-labeled bifunctional radiopharmaceutical, Ga-DOTA-MN2, for hypoxic tumor imaging

    International Nuclear Information System (INIS)

    On the basis of the findings obtained by X-ray crystallography of gadolinium-diethylenetriamine pentaacetic acid (Ga-DOTA) chelates and the drug design concept of bifunctional radiopharmaceuticals, we previously designed and synthesized a radiogallium-labeled DOTA chelate containing two metronidazole moieties, 67Ga-DOTA-MN2, for hypoxic tumor imaging. As expected, 67Ga-DOTA-MN2 exhibited high in vivo stability, although two carboxyl groups in the DOTA skeleton were conjugated with metronidazole moieties. In this study, we evaluated 67/68Ga-DOTA-MN2 as a nuclear imaging agent for hypoxic tumors. 67Ga-labeling of DOTA-MN2 with 67GaCl3 was achieved with high radiochemical yield (>85%) by 1-min of microwave irradiation (50 W). The pharmacokinetics of 67Ga-DOTA-MN2 were examined in mammary carcinoma (FM3A) tumor-bearing mice, and compared with those of 67Ga-DOTA-MN1 containing one metronidazole unit and '67Ga-DOTA. Upon administration, 67Ga-DOTA-MN2 exhibited higher accumulation in the implanted tumors than '67Ga-DOTA. Tumor-to-blood ratios of 67Ga-DOTA-MN2 were about two-fold higher than those of 67Ga-DOTA-MN1. Autoradiographic analysis showed the heterogeneous localization of '67Ga-DOTA-MN2 in the tumors, which corresponds to hypoxic regions suggested by well-established hypoxia marker drug, pimonidazole. Furthermore, in positron emission tomography (PET) study, the tumors of mice administered '68Ga-labeled DOTA-MN2 were clearly imaged by small-animal PET at 1 h after administration. This study demonstrates the potential usefulness of 67/68Ga-DOTA-MN2 as a nuclear imaging agent for hypoxic tumors and suggests that two functional moieties, such as metronidazole, can be conjugated to radiogallium-DOTA chelate without reducing the complex stability. The present findings provide useful information about the chemical design of radiogallium-labeled radiopharmaceuticals for PET and single photon emission computed tomography (SPECT) studies. (author)

  11. Mechanical characterization of a bifunctional Tetronic hydrogel adhesive for soft tissues.

    Science.gov (United States)

    Sanders, Lindsey; Stone, Roland; Webb, Kenneth; Mefford, Thompson; Nagatomi, Jiro

    2015-03-01

    Although a number of tissue adhesives and sealants for surgical use are currently available, attaining a useful balance in high strength, high compliance, and low swelling has proven difficult. Recent studies have demonstrated that a four-arm poly(propylene oxide)-poly(ethylene oxide) block copolymer, Tetronic, can be chemically modified to form a hydrogel tissue adhesive (Cho et al., Acta Biomater 2012;8:2223-2232; Barrett et al., Adv Health Mater 2012;1-11; Balakrishnan, Evaluating mechanical performance of hydrogel-based adhesives for soft tissue applications. Clemson University, All Theses, Paper 1574: Tiger Prints; 2013). Building on the success of these studies, this study explored bifunctionalization of Tetronic with acrylates for chemical crosslinking of the hydrogel and N-hydroxysuccinimide (NHS) for reaction with tissue amines. The adhesive bond strengths of various uni and bifunctional Tetronic blends (T1107 ACR: T1107 ACR/NHS) determined by lap shear testing ranged between 8 and 74 kPa, with the 75:25 (T1107 ACR: T1107 ACR/NHS) blend displaying the highest value. These results indicated that addition of NHS led to improvement of tissue bond strength over acrylation alone. Furthermore, ex vivo pressure tests using the rat bladder demonstrated that the bifunctional Tetronic adhesive exhibited high compliance and maintained pressures under hundreds of filling and emptying cycles. Together, the results of this study provided evidence that the bifunctional Tetronic adhesive with a proper blend ratio may be used to achieve an accurate balance in bulk and tissue bond strengths, as well as the compliance and durability for soft tissue such as the bladder. PMID:25111445

  12. Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

    Science.gov (United States)

    Di Mola, Antonia; Tiffner, Maximilian; Scorzelli, Francesco; Palombi, Laura; Filosa, Rosanna; De Caprariis, Paolo

    2015-01-01

    Summary New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications. PMID:26734105

  13. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  14. Bifunctional Organic Polymeric Catalysts with a Tunable Acid-Base Distance and Framework Flexibility

    Science.gov (United States)

    Chen, Huanhui; Wang, Yanan; Wang, Qunlong; Li, Junhui; Yang, Shiqi; Zhu, Zhirong

    2014-09-01

    Acid-base bifunctional organic polymeric catalysts were synthesized with tunable structures. we demonstrated two synthesis approaches for structural fine-tune. In the first case, the framework flexibility was tuned by changing the ratio of rigid blocks to flexible blocks within the polymer framework. In the second case, we precisely adjusted the acid-base distance by distributing basic monomers to be adjacent to acidic monomers, and by changing the chain length of acidic monomers. In a standard test reaction for the aldol condensation of 4-nitrobenzaldehyde with acetone, the catalysts showed good reusability upon recycling and maintained relatively high conversion percentage.

  15. Bifunctional Brønsted Base Catalyzes Direct Asymmetric Aldol Reaction of α-Keto Amides.

    Science.gov (United States)

    Echave, Haizea; López, Rosa; Palomo, Claudio

    2016-03-01

    The first enantioselective direct cross-aldol reaction of α-keto amides with aldehydes, mediated by a bifunctional ureidopeptide-based Brønsted base catalyst, is described. The appropriate combination of a tertiary amine base and an aminal, and urea hydrogen-bond donor groups in the catalyst structure promoted the exclusive generation of the α-keto amide enolate which reacted with either non-enolizable or enolizable aldehydes to produce highly enantioenriched polyoxygenated aldol adducts without side-products resulting from dehydration, α-keto amide self-condensation, aldehyde enolization, and isotetronic acid formation. PMID:26835655

  16. The Golgi localized bifunctional UDP-rhamnose/UDP-galactose transporter family of Arabidopsis

    DEFF Research Database (Denmark)

    Rautengarten, Carsten; Ebert, Berit; Moreno, Ignacio;

    2014-01-01

    are specifically presumed to deliver the diverse array of nucleotide sugars found in plants. This study has developed a novel approach that enabled functional characterization of six bifunctional UDP-rhamnose (Rha)/UDP-galactose (Gal) transporters from Arabidopsis. An analysis of loss-of-function and...... overexpression lines for two of these transporters identified biochemical alterations supporting their roles in the biosynthesis of Rha- and Gal-containing polysaccharides. Thus, cell wall polysaccharide biosynthesis in the Golgi apparatus of plants is likely also regulated by substrate transport mechanisms....

  17. Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones.

    Science.gov (United States)

    Di Mola, Antonia; Tiffner, Maximilian; Scorzelli, Francesco; Palombi, Laura; Filosa, Rosanna; De Caprariis, Paolo; Waser, Mario; Massa, Antonio

    2015-01-01

    New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications. PMID:26734105

  18. An efficient bifunctional electrocatalyst for water splitting based on cobalt phosphide

    Science.gov (United States)

    Yang, Libin; Qi, Honglan; Zhang, Chengxiao; Sun, Xuping

    2016-06-01

    The development of highly efficient electrocatalysts for water splitting is critical for various renewable-energy technologies. In this letter, we demonstrate a cobalt phosphide nanowire array grown on a Ti mesh (CoP/TM) behaving as a bifunctional electrocatalyst for water splitting. The CoP/TM electrode delivers 10 mA cm‑2 at an overpotential of 72 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER) in 1.0 M KOH. Furthermore, its corresponding two-electrode alkaline electrolyzer displays 10 mA cm‑2 at 1.64 V.

  19. Neurodegeneration in D-bifunctional protein deficiency: diagnostic clues and natural history using serial magnetic resonance imaging

    International Nuclear Information System (INIS)

    We report serial neurodegenerative changes on neuroimaging in a rare peroxisomal disease called D-bifunctional protein deficiency. The pattern of posterior to anterior demyelination with white matter disease resembles X-linked adrenoleukodystrophy. We feel this case is important to (1) highlight that D-bifunctional protein deficiency should be considered in cases where the neuroimaging resembles X-linked adrenoleukodystrophy, (2) to show different stages of progression to help identify this disease using neuroimaging in children, and (3) to show that neuroimaging suggesting a leukodystrophy can warrant peroxisomal beta-oxidation studies in skin fibroblasts even when plasma very long chain fatty acids are normal. (orig.)

  20. Cobalt nanoparticles embedded in N-doped carbon as an efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions

    Science.gov (United States)

    Su, Yunhe; Zhu, Yihua; Jiang, Hongliang; Shen, Jianhua; Yang, Xiaoling; Zou, Wenjian; Chen, Jianding; Li, Chunzhong

    2014-11-01

    Cobalt based catalysts are promising bifunctional electrocatalysts for both oxygen reduction and oxygen evolution reactions (ORR and OER) in unitized regenerative fuel cells (URFCs) operating with alkaline electrolytes. Here we report a hybrid composite of cobalt nanoparticles embedded in nitrogen-doped carbon (Co/N-C) via a solvothermal carbonization strategy. With the synergistic effect arising from the N-doped carbon and cobalt nanoparticles in the composite, the Co/N-C hybrid catalyst exhibits highly efficient bifunctional catalytic activity and excellent stability toward both ORR and OER. The ΔE (oxygen electrode activity parameter for judging the overall electrocatalytic activity of a bifunctional electrocatalyst) value for Co/N-C is 0.859 V, which is smaller than those of Pt/C and most of the non-precious metal catalysts in previous studies. Furthermore, the Co/N-C composite also shows better bifunctional catalytic activity than its oxidative counterparts, which could be attributed to the high specific surface area and the efficient charge transfer ability of the composite, as well as the good synergistic effect between N-doped carbon and the Co nanoparticles in the Co/N-C composite.Cobalt based catalysts are promising bifunctional electrocatalysts for both oxygen reduction and oxygen evolution reactions (ORR and OER) in unitized regenerative fuel cells (URFCs) operating with alkaline electrolytes. Here we report a hybrid composite of cobalt nanoparticles embedded in nitrogen-doped carbon (Co/N-C) via a solvothermal carbonization strategy. With the synergistic effect arising from the N-doped carbon and cobalt nanoparticles in the composite, the Co/N-C hybrid catalyst exhibits highly efficient bifunctional catalytic activity and excellent stability toward both ORR and OER. The ΔE (oxygen electrode activity parameter for judging the overall electrocatalytic activity of a bifunctional electrocatalyst) value for Co/N-C is 0.859 V, which is smaller than those

  1. Preparation of Pt/Irx(IrO2)10 - x bifunctional oxygen catalyst for unitized regenerative fuel cell

    Science.gov (United States)

    Kong, Fan-Dong; Zhang, Sheng; Yin, Ge-Ping; Zhang, Na; Wang, Zhen-Bo; Du, Chun-Yu

    2012-07-01

    Bifunctional Pt/Irx(IrO2)10 - x (x oxygen reduction reaction (ORR) (21.71 mA mg-1 at 0.85 V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35 mA mg-1 at 1.55 V) is also observed for Pt/Ir3(IrO2)7 catalyst. Kinetic analyses indicate that ORR on Pt/Ir3(IrO2)7 catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC.

  2. A central role for bifunctional aspartate/prephenate aminotransferase in the biosynthesis of amino acids in plant plastids.

    OpenAIRE

    El-Azaz, Jorge; Cánovas, Francisco M.; de la Torre, Fernando; Ávila, Concepción

    2014-01-01

    A central role for bifunctional aspartate/prephenate aminotransferase in the biosynthesis of amino acids in plant plastids. Fernando de la Torre, Jorge El-Azaz, Concepción Ávila, Francisco M. Cánovas Departamento de Biología Molecular y Bioquímica. Universidad de Málaga. Bifunctional aspartate/prephenate aminotransferases (AAT/PAT) are plastid-located enzymes encoded by a single locus in all reported plants, which develop two different enzymatic activities: aspartate aminotransferas...

  3. Neurodegeneration in D-bifunctional protein deficiency: diagnostic clues and natural history using serial magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Aneal [University of Calgary, Department of Medical Genetics and Pediatrics, Alberta Children' s Hospital, Calgary, AB (Canada); Wei, Xing-Chang [University of Calgary, Department of Radiology, Alberta Children' s Hospital, Calgary, AB (Canada); Snyder, Floyd F. [Alberta Children' s Hospital, Biochemical Genetics Laboratory, Calgary, AB (Canada); Mah, Jean K. [University of Calgary, Division of Neurology, Department of Pediatrics, Calgary, AB (Canada); Waterham, Hans; Wanders, Ronald J.A. [University of Amsterdam, Academic Medical Center, Lab Genetic Metabolic Diseases, Amsterdam (Netherlands)

    2010-12-15

    We report serial neurodegenerative changes on neuroimaging in a rare peroxisomal disease called D-bifunctional protein deficiency. The pattern of posterior to anterior demyelination with white matter disease resembles X-linked adrenoleukodystrophy. We feel this case is important to (1) highlight that D-bifunctional protein deficiency should be considered in cases where the neuroimaging resembles X-linked adrenoleukodystrophy, (2) to show different stages of progression to help identify this disease using neuroimaging in children, and (3) to show that neuroimaging suggesting a leukodystrophy can warrant peroxisomal beta-oxidation studies in skin fibroblasts even when plasma very long chain fatty acids are normal. (orig.)

  4. {sup 188}Re-labeled bisphosphonates as potential bifunctional agents for therapy in patients with bone metastases

    Energy Technology Data Exchange (ETDEWEB)

    El-Mabhouh, Amal [Faculty of Pharmacy and Pharmaceutical Sciences, 3118 Dentistry Pharmacy Center, University of Alberta, Edmonton Alta, T6G-2N8 (Canada); Mercer, John R. [Faculty of Pharmacy and Pharmaceutical Sciences, 3118 Dentistry Pharmacy Center, University of Alberta, Edmonton Alta, T6G-2N8 (Canada); Faculty of Medicine, 3118 Dentistry Pharmacy Center, University of Alberta, Edmonton Alta, T6G-2N8 (Canada)]. E-mail: john.mercer@ualberta.ca

    2005-04-01

    Two new bisphosphonates have been examined for their ability to bind {sup 188}Re and deliver it selectively to bone. The bisphosphonates are prototype compounds with potential to deliver rhenium radionuclides and a second therapy modality to bone metastases. A conjugate between diethylenetriaminepentaacetic acid and bisphosphonate (DTPA/BP) and a conjugate between 5-fluorouracil and bisphosphonate (5-FU/BP) were prepared and labeled at high radiochemical purity with {sup 188}Re and biodistribution studies were carried out in normal Balb/C mice. The compounds showed rapid blood clearance and elimination from soft tissues with substantial retention of activity in the bone comparable to {sup 188}Re-hydroxyethylidine diphosphonate used as a control. At 8 h bone activity was 3.51% of injected dose for {sup 188}Re-DTPA/BP and 6.38% of injected dose for {sup 188}Re-5-FU/BP representing 69.6% and 80.6% of total body radioactivity, respectively. The two compounds show the potential for combination therapy of painful bone metastases.

  5. Combining the Physical Adsorption Approach and the Covalent Attachment Method to Prepare a Bifunctional Bioreactor

    Directory of Open Access Journals (Sweden)

    Zhi Wang

    2012-09-01

    Full Text Available Aminopropyl-functionalized SBA-15 mesoporous silica was used as a support to adsorb myoglobin. Then, in order to avoid the leakage of adsorbed myoglobin, lysozyme was covalently tethered to the internal and external surface of the mesoporous silica with glutaraldehyde as the coupling agent. The property of amino-functionalized mesoporous silica was characterized by N2 adsorption-desorption and thermogravimetric (TG analysis. The feature of the silica-based matrix before and after myoglobin adsorption was identified by fourier transform infrared (FTIR and UV/VIS measurement. With o-dianisidine and H2O2 as the substrate, the peroxidase activity of adsorbed myoglobin was determined. With Micrococus lysodeilicus as the substrate, the antibacterial activity of covalently tethered lysozyme was measured. Results demonstrated that the final product not only presented peroxidase activity of the myoglobin but yielded antibacterial activity of the lysozyme.

  6. Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces

    Science.gov (United States)

    Choi, Chang-Ho; David, Michele; Gao, Zhongwei; Chang, Alvin; Allen, Marshall; Wang, Hailei; Chang, Chih-Hung

    2016-04-01

    Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface.

  7. Structural basis for the bifunctionality of fructose-1,6-bisphosphate aldolase/phosphatase.

    Science.gov (United States)

    Fushinobu, Shinya; Nishimasu, Hiroshi; Hattori, Daiki; Song, Hyun-Jin; Wakagi, Takayoshi

    2011-10-27

    Enzymes catalyse specific reactions and are essential for maintaining life. Although some are referred to as being bifunctional, they consist of either two distinct catalytic domains or a single domain that displays promiscuous substrate specificity. Thus, one enzyme active site is generally responsible for one biochemical reaction. In contrast to this conventional concept, archaeal fructose-1,6-bisphosphate (FBP) aldolase/phosphatase (FBPA/P) consists of a single catalytic domain, but catalyses two chemically distinct reactions of gluconeogenesis: (1) the reversible aldol condensation of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GA3P) to FBP; (2) the dephosphorylation of FBP to fructose-6-phosphate (F6P). Thus, FBPA/P is fundamentally different from ordinary enzymes whose active sites are responsible for a specific reaction. However, the molecular mechanism by which FBPA/P achieves its unusual bifunctionality remains unknown. Here we report the crystal structure of FBPA/P at 1.5-Å resolution in the aldolase form, where a critical lysine residue forms a Schiff base with DHAP. A structural comparison of the aldolase form with a previously determined phosphatase form revealed a dramatic conformational change in the active site, demonstrating that FBPA/P metamorphoses its active-site architecture to exhibit dual activities. Thus, our findings expand the conventional concept that one enzyme catalyses one biochemical reaction. PMID:21983966

  8. Active-site remodelling in the bifunctional fructose-1,6-bisphosphate aldolase/phosphatase.

    Science.gov (United States)

    Du, Juan; Say, Rafael F; Lü, Wei; Fuchs, Georg; Einsle, Oliver

    2011-10-27

    Fructose-1,6-bisphosphate (FBP) aldolase/phosphatase is a bifunctional, thermostable enzyme that catalyses two subsequent steps in gluconeogenesis in most archaea and in deeply branching bacterial lineages. It mediates the aldol condensation of heat-labile dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) to FBP, as well as the subsequent, irreversible hydrolysis of the product to yield the stable fructose-6-phosphate (F6P) and inorganic phosphate; no reaction intermediates are released. Here we present a series of structural snapshots of the reaction that reveal a substantial remodelling of the active site through the movement of loop regions that create different catalytic functionalities at the same location. We have solved the three-dimensional structures of FBP aldolase/phosphatase from thermophilic Thermoproteus neutrophilus in a ligand-free state as well as in complex with the substrates DHAP and FBP and the product F6P to resolutions up to 1.3 Å. In conjunction with mutagenesis data, this pinpoints the residues required for the two reaction steps and shows that the sequential binding of additional Mg(2+) cations reversibly facilitates the reaction. FBP aldolase/phosphatase is an ancestral gluconeogenic enzyme optimized for high ambient temperatures, and our work resolves how consecutive structural rearrangements reorganize the catalytic centre of the protein to carry out two canonical reactions in a very non-canonical type of bifunctionality. PMID:21983965

  9. Subnanometer Cobalt-Hydroxide-Anchored N-Doped Carbon Nanotube Forest for Bifunctional Oxygen Catalyst.

    Science.gov (United States)

    Kim, Ji Eun; Lim, Joonwon; Lee, Gil Yong; Choi, Sun Hee; Maiti, Uday Narayan; Lee, Won Jun; Lee, Ho Jin; Kim, Sang Ouk

    2016-01-27

    Electrochemical oxygen redox reactions are the crucial elements for energy conversion and storage including fuel cells and metal air batteries. Despite tremendous research efforts, developing high-efficient, low-cost, and durable bifunctional oxygen catalysts remains a major challenge. We report a new class of hybrid material consisting of subnanometer thick amorphous cobalt hydroxide anchored on NCNT as a durable ORR/OER bifunctional catalyst. Although amorphous cobalt species-based catalysts are known as good OER catalysts, hybridizing with NCNT successfully enhanced ORR activity by promoting a 4e reduction pathway. Abundant charge carriers in amorphous cobalt hydroxide are found to trigger the superior OER activity with high current density and low Tafel slope as low as 36 mV/decade. A remarkably high OER turnover frequency (TOF) of 2.3 s(-1) at an overpotential of 300 mV was obtained, one of the highest values reported so far. Moreover, the catalytic activity was maintained over 120 h of cycling. The unique subnanometer scale morphology of amorphous hydroxide cobalt species along with intimate cobalt species-NCNT interaction minimizes the deactivation of catalyst during prolonged repeated cycles. PMID:26766495

  10. Highly Efficient and Robust Nickel Phosphides as Bifunctional Electrocatalysts for Overall Water-Splitting.

    Science.gov (United States)

    Li, Jiayuan; Li, Jing; Zhou, Xuemei; Xia, Zhaoming; Gao, Wei; Ma, Yuanyuan; Qu, Yongquan

    2016-05-01

    To search for the efficient non-noble metal based and/or earth-abundant electrocatalysts for overall water-splitting is critical to promote the clean-energy technologies for hydrogen economy. Herein, we report nickel phosphide (NixPy) catalysts with the controllable phases as the efficient bifunctional catalysts for water electrolysis. The phases of NixPy were determined by the temperatures of the solid-phase reaction between the ultrathin Ni(OH)2 plates and NaH2PO2·H2O. The NixPy with the richest Ni5P4 phase synthesized at 325 °C (NixPy-325) delivered efficient and robust catalytic performance for hydrogen evolution reaction (HER) in the electrolytes with a wide pH range. The NixPy-325 catalysts also exhibited a remarkable performance for oxygen evolution reaction (OER) in a strong alkaline electrolyte (1.0 M KOH) due to the formation of surface NiOOH species. Furthermore, the bifunctional NixPy-325 catalysts enabled a highly performed overall water-splitting with ∼100% Faradaic efficiency in 1.0 M KOH electrolyte, in which a low applied external potential of 1.57 V led to a stabilized catalytic current density of 10 mA/cm(2) over 60 h. PMID:27064172

  11. Construction of a bifunctional enzyme fusion for the combined determination of biogenic amines in foods.

    Science.gov (United States)

    Lee, Jae-Ick; Jang, Jun-Hyuck; Yu, Mi-Ji; Kim, Young-Wan

    2013-09-25

    Biogenic amines (BAs) are a group of low-molecular-mass organic bases derived from free amino acids. Due to the undesirable effects of BAs on human health, amine oxidase-based detection methods for BAs in foods have been developed. Here, we developed a bifunctional enzyme fusion (MAPO) using a Cu(2+)-containing monoamine oxidase (AMAO2) and a flavin adenine dinucleotide-containing putrescine oxidase (APUO) from Arthrobacter aurescens. It was necessary to activate MAPO with supplementary Cu(2+) ions, leading to a 6- to 12-fold improvement in catalytic efficiency (kcat/KM) for monoamines. The optimal temperatures of Cu(2+)-activated MAPO (cMAPO) for both tyramine and putrescine were 50 °C, and the optimal pH values for tyramine and putrescine were pH 7.0 and pH 8.0, respectively, consistent with those of AMAO2 and APUO, respectively. The cMAPO showed relative specific activities of 100, 99, 32, and 32 for 2-phenylethylamine, tyramine, histamine, and putrescine, respectively. The tyramine-equivalent BA contents of fermented soybean pastes by cMAPO were more than 90% of the total BA determined by HPLC. In conclusion, cMAPO is fully bifunctional toward biogenic monoamines and putrescine, allowing the combined determination of multiple BAs in foods. This colorimetric determination method could be useful for point-of-care testing to screen safety-guaranteed products prior to instrumental analyses. PMID:24001036

  12. Bifunctional composite microspheres of silica/lanthanide-polyoxometalates/Au: Study on luminescence and catalytic properties

    International Nuclear Information System (INIS)

    In this paper, the synthesis and properties of composite silica microspheres grafted with gold nanoparticles and lanthanide-polyoxometalates are described. This synthesis employs polyethyleneimine as the crosslink polymer to immobilize the Au nanoparticles and lanthanide-polyoxometalates on silica spheres, which results in the formation of bifunctional composite microspheres of silica/lanthanide-polyoxometalates/Au. The composite material was found to be catalytically active in the oxidation of styrene, and benzaldehyde and styrene oxide were the main products. Catalyzed oxidation of styrene demonstrates the size-dependent activity of catalysts and the smaller catalyst shows the higher selectivity. Moreover, the composite particles show bright red luminescence under UV light, which could be seen by naked eyes. The luminescence properties of composite material and the effect of Au nanoparticles on the luminescence of Eu ion were investigated, and energy could be more effectively transferred from ligand to lanthanide ion when Au nanoparticles were grafted on silica spheres. The integration of luminescent components and Au particles makes it possible to label catalyst and monitor the catalyzed reactions. - Highlights: • The bifunctional composite microspheres were fabricated. • Both polyoxometalates and Au nanoparticles could be grafted on silica spheres. • The composite particles exhibit the excellent luminescence and catalytic activity. • The Au nanoparticles affect the luminescence properties of Eu3+ ions

  13. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices

    Science.gov (United States)

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-01-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices. PMID:27142285

  14. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices.

    Science.gov (United States)

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-01-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices. PMID:27142285

  15. Antifungal agents.

    Science.gov (United States)

    Ryder, N S

    1999-12-01

    At this year's ICAAC Meeting, new data on approximately 20 different antifungal agents were presented, while no new agents were disclosed. Drugs in late development include the triazoles, voriconazole (Pfizer Ltd) and Sch-56592 (Schering-Plough Corp), and the echinocandins, caspofungin (Merck & Co Inc) and FK-463 (Fujisawa Pharmaceutical Co Ltd). In contrast to previous years, presentations on these and earlier developmental compounds were relatively modest in scope, with few significant new data. Little new information appeared on the most recent novel class of agents, the sordarins (Glaxo Wellcome plc). Early clinical results were presented for FK-463, showing acceptable tolerability and dose-dependent efficacy in AIDS-associated esophageal candidiasis. A new liposomal formulation of nystatin (Nyotran; Aronex Pharmaceuticals Inc) was shown to be equivalent to conventional amphotericin B in empiric therapy of presumed fungal infection in neutropenic patients, but with reduced toxicity. Intravenous itraconazole (Janssen Pharmaceutica NV) was an effective prophylactic therapy in invasive pulmonary aspergillosis, while oral itraconazole was discussed as a treatment for fungal infection in heart and liver transplant patients. The allylamine compound, terbinafine (Novartis AG), showed good clinical efficacy against fungal mycetoma, a serious tropical infection. A major highlight was the first presentation of inhibitors of fungal efflux pumps as a strategy for overcoming resistance. MC-510027 (milbemycin alpha-9; Microcide Pharmaceuticals Inc) and its derivatives, potentiated the antifungal activity of triazoles and terbinafine in a number of Candida spp. Another pump inhibitor, MC-005172 (Microcide Pharmaceuticals Inc) showed in vivo potentiation of fluconazole in a mouse kidney infection model. Microcide Pharmaceuticals Inc also presented inhibitors of bacterial efflux pumps. PMID:16113946

  16. Trading Agents

    CERN Document Server

    Wellman, Michael

    2011-01-01

    Automated trading in electronic markets is one of the most common and consequential applications of autonomous software agents. Design of effective trading strategies requires thorough understanding of how market mechanisms operate, and appreciation of strategic issues that commonly manifest in trading scenarios. Drawing on research in auction theory and artificial intelligence, this book presents core principles of strategic reasoning that apply to market situations. The author illustrates trading strategy choices through examples of concrete market environments, such as eBay, as well as abst

  17. 偶联剂Si69原位改性淀粉/NR复合材料的性能研究%Study on Properties of Starch/NR Composite Prepared by In-situ Modification of Starch with Coupling Agent Si69

    Institute of Scientific and Technical Information of China (English)

    艾军伟; 刘芳; 曾宗强; 朱立新; 贾德民

    2011-01-01

    The starch,tNR compositcs were prepared by in-situ modification of starch with coupling agent Si69,and the influence of coupling agent Si69 on the properties of composite were investigated. The results showed that, the interaction between starch and NR could be strengthened by in-situ modification of starch with coupling agent Si69,and the dispersion of starch in NR matrix was improved. It was found that Si69 had chemical reaction with starch and participated in the vulcanization of NR to improve physical properties of the composite.%采用原位法制备偶联剂Si69改性淀粉/NR复合材料,并研究偶联剂Si69对复合材料性能的影响.结果表明:采用偶联剂Si69对淀粉进行原位改性可以增强淀粉与NR的界面相互作用,改善淀粉在NR中的分散性;偶联剂Si69与淀粉发生了化学作用,并参与了NR的硫化,从而提高复合材料的物理性能.

  18. Pd(0)@UiO-68-AP: chelation-directed bifunctional heterogeneous catalyst for stepwise organic transformations.

    Science.gov (United States)

    Li, Yan-An; Yang, Song; Liu, Qi-Kui; Chen, Gong-Jun; Ma, Jian-Ping; Dong, Yu-Bin

    2016-05-01

    A bifunctional heterogeneous catalyst Pd(0)@UiO-68-AP based on a chelation-directed post-synthetic approach is reported. It exhibits typical heterogeneous catalytic behaviour and can promote benzyl alcohol oxidiation-Knoevenagel condensation in a stepwise way. PMID:27035589

  19. Complexation and biodistribution study of 111In complexes of bifunctional phosphinic acid analogues of H4DOTA

    Czech Academy of Sciences Publication Activity Database

    Forsterová, Michaela; Zimová, Jana; Petrík, M.; Lázníček, M.; Lázníčková, A.; Hermann, P.; Melichar, František

    2007-01-01

    Roč. 2, č. 337 (2007), s. 34-34. ISSN 1619-7070 R&D Projects: GA AV ČR 1QS100480501 Institutional research plan: CEZ:AV0Z10480505 Keywords : bifunctional H4DOTA ligands * phosphinic acid analogues, * complexation of 111In Subject RIV: FR - Pharmacology ; Medidal Chemistry

  20. Bifunctional, Carbon-Free Nickel/Cobalt-Oxide Cathodes for Lithium-Air Batteries with an Aqueous Alkaline Electrolyte

    International Nuclear Information System (INIS)

    Highlights: • High activity bi-functional catalyst combination for ORR and OER . • An optimum ratio of high active bi-functional catalysts was found. • Novel electrodes without carbon to avoid carbon corrosion during OER mode. • EIS model for OER describes influence of a growing oxide layers. • Long-term test exhibited an excellent long-term stability over 1200 cycles. - Abstract: Lithium-air batteries with an aqueous alkaline electrolyte promise a very high practical energy density and capacity. These batteries are mainly limited by high overpotentials on the bifunctional cathode during charge and discharge. To reduce overpotentials the bifunctional cathode of such batteries must be improved significantly. Nickel is relatively inexpensive and has a good catalytic activity in alkaline media. Co3O4 was found to be a promising metal oxide catalyst for oxygen evolution in alkaline media but it has a low electronic conductivity. On the other hand since nickel has a good electronic conductivity Co3O4 can be added to pure nickel electrodes to enhance performance due to a synergetic effect. Due to the poor stability of carbon materials at high anodic potentials, gas diffusion electrodes were prepared without carbon to improve especially long-term stability. Gas diffusion electrodes were electrochemically investigated in a half cell. In addition, cyclic voltammogrametry (CV) and electrochemical impedance spectroscopy (EIS) were carried out. SEM was used for the physical and morphological investigations. Investigations showed that electrodes containing 20 wt.% Co3O4 exhibited the highest performance

  1. Scalable Fabrication of Nanoporous Carbon Fiber Films as Bifunctional Catalytic Electrodes for Flexible Zn-Air Batteries.

    Science.gov (United States)

    Liu, Qin; Wang, Yaobing; Dai, Liming; Yao, Jiannian

    2016-04-01

    A flexible nanoporous carbon-fiber film for wearable electronics is prepared by a facile and scalable method through pyrolysis of electrospun polyimide. It exhibits excellent bifunctional electrocatalytic activities for oxygen reduction and oxygen evolution. Flexible rechargeable zinc-air batteries based on the carbon-fiber film show high round-trip efficiency and mechanical stability. PMID:26914270

  2. Biological evaluation of 99mTC cis-Pt iminoacetic acid complexes as tumour imaging agents

    International Nuclear Information System (INIS)

    The biodistributions of three new 99mTc labelled cis-platinum bifunctional tumour imaging agents were examined in mice bearing a certain type of sarcoma between 15 minutes and 24 hours post injection. The three complexes were excreted primarily via the renal pathway into the urine but at quite different rates. All complexes had some affinity for the tumour, but complexes III had the greatest, with tumour to blood and tumour to muscle rates at 24 hours in excess of 10:1 and 18:1. Biodistribution results were calculated using Tiscon Program. Suggesting that the three complexes may be useful as tumour imaging agents. (M.E.L.)

  3. Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

    International Nuclear Information System (INIS)

    This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

  4. Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

    Science.gov (United States)

    Thamake, S. I.; Raut, S. L.; Ranjan, A. P.; Gryczynski, Z.; Vishwanatha, J. K.

    2011-01-01

    This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

  5. Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Thamake, S I; Raut, S L [Department of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 (United States); Ranjan, A P; Vishwanatha, J K [Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Gryczynski, Z, E-mail: jamboor.vishwanatha@unthsc.edu [Center for Commercialization of Fluorescence Technology, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

    2011-01-21

    This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

  6. Radioprotective Agents

    Directory of Open Access Journals (Sweden)

    Ilker Kelle

    2008-01-01

    Full Text Available Since1949, a great deal of research has been carried out on the radioprotective activity of various chemical substances. Thiol compounds, compounds which contain –SH radical, different classes of pharmacological agents and other compounds such as vitamine C and WR-2721 have been shown to reduce mortality when administered prior to exposure to a lethal dose of radiation. Recently, honey bee venom as well as that of its components melittin and histamine have shown to be valuable in reduction of radiation-induced damage and also provide prophylactic alternative treatment for serious side effects related with radiotherapy. It has been suggested that the radioprotective activity of bee venom components is related with the stimulation of the hematopoetic system.

  7. A nanostructured bifunctional Pd/C gas-diffusion electrode for metal-air batteries

    International Nuclear Information System (INIS)

    Graphical Abstract: Images showing (a) a scanning electrode microscope cross section of the Pd/C air electrode, (b) a TEM micrograph of the Pd/C catalyst, and (c) charge–discharge cycling of the air electrode in 6 mol dm−3 KOH at 20 mA cm−2 under 100 ml min−1 oxygen flow. - Highlights: • The Pd/C air electrode shows consistent good performance at modest current densities (20–80 mA cm−2), and is stable for 1000 cycles at room temperature. • The Pd/C air electrode has a potential difference of 0.53 V between oxygen evolution and oxygen reduction. • The air electrode makes efficient use of a small precious metal loading (0.5 mg cm−2), and is mainly made from lightweight carbon materials. • The air electrode has better stability than a commercial 2 mg cm−2 Pt/C electrode on repeated charge–discharge cycling, despite having a lower (and therefore less expensive) loading of catalyst. - Abstract: Designing a bifunctional air electrode which catalyses both the oxygen reduction and oxygen evolution reactions is an essential part of progress towards fully rechargeable metal-air batteries, such as the iron-air battery which is environmentally friendly, low cost, and does not suffer risk of thermal runaway like lithium-ion batteries. This paper reports the development of a lightweight carbon-based bifunctional air electrode, catalysed by a small (0.5 mg cm−2) loading of 30 wt.% palladium on carbon. The Pd-catalysed air electrode showed good bifunctional activity, with 0.53 V potential difference between oxygen reduction and evolution. The Pd/C air electrode showed improved catalytic activity at high current densities (≥ 50 mA cm−2) and enhanced durability compared with two commercial Pt/C air electrodes produced by Gaskatel GmbH and Johnson Matthey. A stable oxygen evolution potential was maintained over 1,000 charge-discharge cycles

  8. Oxygen electrode bifunctional electrocatalyst NiCo2O4 spinel

    Science.gov (United States)

    Fielder, William L.; Singer, Joseph

    1988-01-01

    A significant increase in energy density may be possible if a two-unit alkaline regenerative H2-O2 fuel cell is replaced with a single-unit system that uses passive means for H2O transfer and thermal control. For this single-unit system, new electrocatalysts for the O2 electrode will be required which are not only bifunctionally active but also chemically and electrochemically stable between the voltage range of about 0.7 and 1.5 V. NiCo2O4 spinel is reported to have certain characteristics that make it useful for a study of electrode fabrication techniques. High surface area NiCo2O4 powder was fabricated into unsupported, bifunctional, PTFE-bonded, porous gas fuel cell electrodes by commercial sources using varying PTFE contents and sintering temperatures. The object of this study is to measure the bifunctional activities of these electrodes and to observe what performance differences might result from different commercial electrode fabricators. O2 evolution and O2 reduction data were obtained at 80 C (31 percent KOH). An irreversible reaction (i.e., aging) occurred during O2 evolution at potentials greater than about 1.5 V. Anodic Tafel slopes of 0.06 and 0.12 V/decade were obtained for the aged electrodes. Within the range of 15 to 25 percent, the PTFE content was not a critical parameter for optimizing the electrode for O2 evolution activity. Sintering temperatures between 300 and 340 C may be adequate but heating at 275 C may not be sufficient to properly sinter the PTFE-NiCo2O4 mixture. Electrode disintegration was observed during O2 reduction. Transport of O2 to the NiCo2O4 surface became prohibitive at greater than about -0.02 A/sq cm. Cathodic Tafel slopes of -0.6 and -0.12 V/decade were assumed for the O2 reduction process. A PTFE content of 25 percent (or greater) appears to be preferable for sintering the PTFE-NiCo2O4 mixture.

  9. Study on the uptake and distribution of gadolinium based contrast agents in biological samples using laser ablation with inductively coupled plasma mass spectroscopy; Untersuchungen zur Aufnahme und Verteilung von gadoliniumbasierten Kontrastmitteln in biologischen Proben mittels Laserablation mit induktiv gekoppelter Plasma-Massenspektrometrie

    Energy Technology Data Exchange (ETDEWEB)

    Lingott, Jana

    2016-01-05

    Gadolinium based contrast agents are used for magnetic resonance imaging. After their excretion by medicated patients they reach surface water passing waste water treatment plants where they are not removed sufficiently. The behavior of the contrast agents in the environment and the interaction with organisms was investigated in this work due to the toxicity of the free Gd{sup 3+} ion and the associated risks, such as accumulation in the human food chain. In this work, the two elemental analytical imaging methods laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and synchrotron radiation X-ray fluorescence analysis (SRXRF) have been used to investigate the uptake, distribution, and excretion of Gd-based contrast agents by various biological systems. Both methods were analytically characterized and compared for this application. The detection limits of gadolinium were determined under optimized conditions by LA-ICP-MS and SRXRF. With calibration by remains of dried elemental standard droplets detection limits of 0.78 pg absolute amount of gadolinium (LA-ICP-MS), respectively 89 pg (SRXRF) were reached. Based on filamentous algae as water plants the uptake and the excretion of Gd-based contrast agents were revealed. The dependence on concentration of the contrast agent in the exposition solution and the independence of temporal uptake within one to seven days were studied for duckweed. By LA-ICP-MS gadolinium was quantified in a leaf of cress plant. The verification of the results was performed by SRXRF and ICP-MS after digestion. Furthermore, the uptake and distribution of Gd-based contrast agents in higher organisms (water flea) were observed. The exact location of gadolinium was resolved by three-dimensional μ-computed tomography by the comparison of an exposed with a Gd-free water flea. In all studies, gadolinium was detected in the investigated exposed model organisms. It can be concluded that the contrast agents were taken from the

  10. Synthesis and functionalization of bifunctional chelates for 64Cu complexation for their applications by positron emission tomography (PET) imaging and radiotherapy

    International Nuclear Information System (INIS)

    This work aimed to develop a new family of bis-pidine-type ligands for copper(II) complexation with applications in Positron Emission Tomography (PET). Indeed, copper 64 is a radioelement whose study in PET imaging is booming. Bis-pidines have the benefit of having a rigid and pre-organized structure for complexation of a large number of transition metals. In this work we present the synthesis and optimization of new ligands whose structural and physico-chemical properties have been studied. One ligand showed very good results because it possesses all of kinetic and thermodynamic parameters which are necessary for its application to PET imaging. Different strategies of functionalization have been studied to obtain bifunctional chelates. A lysine derivative has been coupled to a maleimide function (regio-selective of cysteines), to abiotine (which displays a strong affinity for streptavidin) or to a Bodipy pattern for obtaining a bimodal probe (UV-visible and PET). Finally, we present an extension of this bis-pidine family by increasing the number of coordination functions or by synthesizing tricyclic compounds to modulate the selectivity of these molecules. (author)

  11. An agent framework for dynamic agent retraining: Agent academy

    OpenAIRE

    Mitkas, P.; A. Symeonidis; Kechagias, D.; Athanasiadis, I.N.; Laleci, G.; KURT, G.; Kabak, Y.; Acar, A.; Dogac, A.

    2004-01-01

    Agent Academy (AA) aims to develop a multi-agent society that can train new agents for specific or general tasks, while constantly retraining existing agents in a recursive mode. The system is based on collecting information both from the environment and the behaviors of the acting agents and their related successes/failures to generate a body of data, stored in the Agent Use Repository, which is mined by the Data Miner module, in order to generate useful knowledge about the application domai...

  12. Bifunctional Nanoparticle-SILP Catalysts (NPs@SILP) for the Selective Deoxygenation of Biomass Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Luska, Kylie L. [RWTH Aachen Univ. (Germany); Julis, Jennifer [RWTH Aachen Univ. (Germany); Evonik Industries AG, Marl (Germany); Stavitski, Eli [Brookhaven National Lab. (BNL), Upton, NY (United States); Zakharov, Dmitri N. [Brookhaven National Lab. (BNL), Upton, NY (United States); Adams, Alina [RWTH Aachen Univ. (Germany); Leitner, Walter [RWTH Aachen Univ. (Germany); Max Planck Inst. for Coal Research, Ruhr (Germany)

    2014-08-27

    We immobilized ruthenium nanoparticles onto an acidic supported ionic liquid phase (RuNPs@SILP) in the development of bifunctional catalysts for the selective deoxygenation of biomass substrates. RuNPs@SILPs possessed high catalytic activities, selectivities and recyclabilities in the hydrogenolytic deoxygenation and ring opening of C8- and C9-substrates derived from furfural or 5-hydroxymethylfurfural and acetone. When we tailor the acidity of the SILP through the ionic liquid loading provided a molecular parameter by which the catalytic activity and selectivity of the RuNPs@SILPs were controlled to provide a flexible catalyst system toward the formation of different classes of value-added products: cyclic ethers, primary alcohols or aliphatic ethers.

  13. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant

    Science.gov (United States)

    Sui, Tianyi; Song, Baoyu; Wen, Yu-Ho; Zhang, Feng

    2016-03-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands.

  14. Dyes as bifunctional markers of DNA hybridization on surfaces and mutation detection.

    Science.gov (United States)

    García-Mendiola, Tania; Cerro, María Ramos; López-Moreno, José María; Pariente, Félix; Lorenzo, Encarnación

    2016-10-01

    The interaction of small molecules with DNA has found diagnostic and therapeutic applications. In this work, we propose the use of two different dyes, in particular Azure A and Safranine, as bifunctional markers of on-surface DNA hybridization and potent tools for screening of specific gene mutations directly in real DNA PCR amplicons extracted from blood cells. By combining spectroscopic and electrochemical methods we demonstrate that both dyes can interact with single and double stranded DNA to a different extent, allowing reliable hybridization detection. From these data, we have also elucidated the nature of the interaction. We conclude that the binding mode is fundamentally intercalative with an electrostatic component. The dye fluorescence allows their use as nucleic acid stains for the detection of on-surfaces DNA hybridization. Its redox activity is exploited in the development of selective electrochemical DNA biosensors. PMID:27317997

  15. Synthesis and application of glycolic esters in methanol-gasoline as bifunctional additives

    International Nuclear Information System (INIS)

    To explore new and multifunctional additives for methanol-gasoline, glycolic esters were synthesized and screened as phase stabilizer and saturation vapor pressure depressor. The effect of the esters structure on the efficiency was discussed. It was found that the stability of the blends depend on the length of the glycolic esters' alkoxy group, and hexyl glycolic and octyl glycolic were found to be the most effective in various gasoline-methanol blends. Additionally, the glycolic esters can depress the saturation vapor pressure of methanol-gasoline effectively as well, and decyl glycolic is the most effective one. With these data, it can be concluded that the glycolic esters have the great potential to be used as bifunctional gasoline-methanol additives. (author)

  16. A Bifunctional Electrocatalyst for Oxygen Evolution and Oxygen Reduction Reactions in Water

    Science.gov (United States)

    Faschinger, Felix; Chattopadhyay, Samir; Bhakta, Snehadri; Mondal, Biswajit; Elemans, Johannes A. A. W.; Müllegger, Stefan; Tebi, Stefano; Koch, Reinhold; Klappenberger, Florian; Paszkiewicz, Mateusz; Barth, Johannes V.; Rauls, Eva; Aldahhak, Hazem; Schmidt, Wolf Gero

    2016-01-01

    Abstract Oxygen reduction and water oxidation are two key processes in fuel cell applications. The oxidation of water to dioxygen is a 4 H+/4 e− process, while oxygen can be fully reduced to water by a 4 e−/4 H+ process or partially reduced by fewer electrons to reactive oxygen species such as H2O2 and O2 −. We demonstrate that a novel manganese corrole complex behaves as a bifunctional catalyst for both the electrocatalytic generation of dioxygen as well as the reduction of dioxygen in aqueous media. Furthermore, our combined kinetic, spectroscopic, and electrochemical study of manganese corroles adsorbed on different electrode materials (down to a submolecular level) reveals mechanistic details of the oxygen evolution and reduction processes.

  17. Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Fratoddi Ilaria

    2011-01-01

    Full Text Available Abstract Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand.

  18. Bi-functional biobased packing of the cassava starch, glycerol, licuri nanocellulose and red propolis.

    Directory of Open Access Journals (Sweden)

    Samantha Serra Costa

    Full Text Available The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4% and glycerol (1.0%, reinforced with cellulose nanocrystals (0-1% and activated with alcoholic extracts of red propolis (0.4 to 1.0%. The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage.

  19. Bi-Functional Biobased Packing of the Cassava Starch, Glycerol, Licuri Nanocellulose and Red Propolis

    Science.gov (United States)

    Costa, Samantha Serra; Druzian, Janice Izabel; Machado, Bruna Aparecida Souza; de Souza, Carolina Oliveira; Guimarães, Alaíse Gil

    2014-01-01

    The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4%) and glycerol (1.0%), reinforced with cellulose nanocrystals (0–1%) and activated with alcoholic extracts of red propolis (0.4 to 1.0%). The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage. PMID:25383783

  20. On the molecular basis of D-bifunctional protein deficiency type III.

    Directory of Open Access Journals (Sweden)

    Maija L Mehtälä

    Full Text Available Molecular basis of D-bifunctional protein (D-BP deficiency was studied with wild type and five disease-causing variants of 3R-hydroxyacyl-CoA dehydrogenase fragment of the human MFE-2 (multifunctional enzyme type 2 protein. Complementation analysis in vivo in yeast and in vitro enzyme kinetic and stability determinants as well as in silico stability and structural fluctuation calculations were correlated with clinical data of known patients. Despite variations not affecting the catalytic residues, enzyme kinetic performance (K(m, V(max and k(cat of the recombinant protein variants were compromised to a varying extent and this can be judged as the direct molecular cause for D-BP deficiency. Protein stability plays an additional role in producing non-functionality of MFE-2 in case structural variations affect cofactor or substrate binding sites. Structure-function considerations of the variant proteins matched well with the available data of the patients.

  1. RNA Secondary Structure Modulates FMRP's Bi-Functional Role in the MicroRNA Pathway.

    Science.gov (United States)

    Kenny, Phillip; Ceman, Stephanie

    2016-01-01

    MicroRNAs act by post-transcriptionally regulating the gene expression of 30%-60% of mammalian genomes. MicroRNAs are key regulators in all cellular processes, though the mechanism by which the cell activates or represses microRNA-mediated translational regulation is poorly understood. In this review, we discuss the RNA binding protein Fragile X Mental Retardation Protein (FMRP) and its role in microRNA-mediated translational regulation. Historically, FMRP is known to function as a translational suppressor. However, emerging data suggests that FMRP has both an agonistic and antagonistic role in regulating microRNA-mediated translational suppression. This bi-functional role is dependent on FMRP's interaction with the RNA helicase Moloney leukemia virus 10 (MOV10), which modifies the structural landscape of bound mRNA, therefore facilitating or inhibiting its association with the RNA-Induced Silencing Complex. PMID:27338369

  2. A sustainable method inspired by nature for the production of original bi-functional nutraceuticals containing prebiotic fibers and highly bio-available forms of calcium and magnesium

    OpenAIRE

    Goffin, Dorothée; Blecker, Christophe; Paquot, Michel

    2012-01-01

    A sustainable method inspired by nature is proposed leading to an original bifunctional product active on gut health, metabolism regulation, immunity and mineral fortification, fighting against topical chronic diseases (type2 diabetes, osteoporosis, colon cancer…). Peer reviewed

  3. Cobalt Selenide Nanostructures: An Efficient Bifunctional Catalyst with High Current Density at Low Coverage.

    Science.gov (United States)

    Masud, Jahangir; Swesi, Abdurazag T; Liyanage, Wipula P R; Nath, Manashi

    2016-07-13

    Electrodeposited Co7Se8 nanostructures exhibiting flake-like morphology show bifunctional catalytic activity for oxygen evolution and hydrogen evolution reaction (OER and HER, respectively) in alkaline medium with long-term durability (>12 h) and high Faradaic efficiency (99.62%). In addition to low Tafel slope (32.6 mV per decade), the Co7Se8 OER electrocatalyst also exhibited very low overpotential to achieve 10 mA cm(-2) (0.26 V) which is lower than other transition metal chalcogenide based OER electrocatalysts reported in the literature and significantly lower than the state-of-the-art precious metal oxides. A low Tafel slope (59.1 mV per decade) was also obtained for the HER catalytic activity in alkaline electrolyte. The OER catalytic activity could be further improved by creating arrays of 3-dimensional rod-like and tubular structures of Co7Se8 through confined electrodeposition on lithographically patterned nanoelectrodes. Such arrays of patterned nanostructures produced exceptionally high mass activity and gravimetric current density (∼68 000 A g(-1)) compared to the planar thin films (∼220 A g(-1)). Such high mass activity of the catalysts underlines reduction in usage of the active material without compromising efficiency and their practical applicability. The catalyst layer could be electrodeposited on different substrates, and an effect of the substrate surface on the catalytic activity was also investigated. The Co7Se8 bifunctional catalyst enabled water electrolysis in alkaline solution at a cell voltage of 1.6 V. The electrodeposition works with exceptional reproducibility on any conducting substrate and shows unprecedented catalytic performance especially with the patterned growth of catalyst rods and tubes. PMID:27309595

  4. Gently reduced graphene oxide incorporated into cobalt oxalate rods as bifunctional oxygen electrocatalyst

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: Water-oxygen electrochemistry is at the heart of key renewable energy technologies (fuel cells, electrolyzers, and metal-air batteries) due to the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Although much effort has been devoted to the development of improved bifunctional electrocatalysts, an inexpensive, highly active oxygen electrocatalyst, however, remains to be a challenge. In this paper, we present a facile and robust method to create gently reduced graphene oxide incorporated into cobalt oxalate microstructures (CoC2O4/gRGO) and demonstrate its excellent and stable electrocatalytic activity in both OER and ORR, arising from the inherent properties of the components and their physicochemical interaction. Our synthesis technique also explores a single pot method to partially reduce graphene oxide and form CoC2O4 structures while maintaining the solution processability of reduced graphene oxide. While the OER activity of CoC2O4/gRGO is exclusively due to CoC2O4, which transformed into OER-active Co species, the combination with gRGO significantly improves OER stability. On the other hand, CoC2O4/gRGO exhibits synergistic effect towards ORR, via a quasi-four-electron pathway, leading to a slightly higher ORR limiting current than Pt/C. Remarkably, gRGO offers dual functionality, contributing to ORR activity via the N-functional groups and also enhancing OER stability through the gRGO coating around CoC2O4 structures. Our results suggest a new class of metal-carbon composite that has the potential to be alternative bifunctional catalysts for regenerative fuel cells and metal-air batteries

  5. Dimerization and Bifunctionality Confer Robustness to the Isocitrate Dehydrogenase Regulatory System in Escherichia coli*

    Science.gov (United States)

    Dexter, Joseph P.; Gunawardena, Jeremy

    2013-01-01

    An important goal of systems biology is to develop quantitative models that explain how specific molecular features give rise to systems-level properties. Metabolic and regulatory pathways that contain multifunctional proteins are especially interesting to study from this perspective because they have frequently been observed to exhibit robustness: the ability for a system to perform its proper function even as levels of its components change. In this study, we use extensive biochemical data and algebraic modeling to develop and analyze a model that shows how robust behavior arises in the isocitrate dehydrogenase (IDH) regulatory system of Escherichia coli, which was shown in 1985 to experimentally exhibit robustness. E. coli IDH is regulated by reversible phosphorylation catalyzed by the bifunctional isocitrate dehydrogenase kinase/phosphatase (IDHKP), and the level of IDH activity determines whether carbon flux is directed through the glyoxylate bypass (for growth on two-carbon substrates) or the full tricarboxylic acid cycle. Our model, which incorporates recent structural data on IDHKP, identifies several specific biochemical features of the system (including homodimerization of IDH and bifunctionality of IDHKP) that provide a potential explanation for robustness. Using algebraic techniques, we derive an invariant that summarizes the steady-state relationship between the phospho-forms of IDH. We use the invariant in combination with kinetic data on IDHKP to calculate IDH activity at a range of total IDH levels and find that our model predicts robustness. Our work unifies much of the known biochemistry of the IDH regulatory system into a single quantitative framework and highlights the importance of constructing biochemically realistic models in systems biology. PMID:23192354

  6. Bifunctional Effect of Human IFN-γon Cultured Human Fibroblasts from Tenon's Capsule

    Institute of Scientific and Technical Information of China (English)

    Yan Guo; Jian Ge; Haiquan Liu; Yanyan Li; Jianliang Zheng; Xiangkun Huang; Yuqing Lan

    2000-01-01

    Purpose: To study the effect of human IFN-γ on in vitro cultured human fibroblasts from Tenon's capsuleMaterials and methods: The effect of different concentrations of human IFN-γ and mitomycin-C (MMC), 5-fluorouracil (5-Fu) on cultured human Tenon's capsule fibroblasts (HTCF) was measured using a MIT [3-(4, 5-dimethylthiazo-2-yl)] -2,5-diphenyltetrazolium bromide; Thiazolyl blue) colorimetric assay. The results were analyzed using ANOVA of the statistical package for social sciences (SPSS) 9.0version. The difference was considered to be significant if P < 0. 05.Results: The effects of MMC and 5-Fu on the growth of HTCF were negative, while the effects of IFN-γ on the growth of HTCF were both negative (102 ~ l04 units/ml in two experiments) and positive (106, 105, 10 units/ml in two experiments) . The inhibition rate of MMC ranged from 5.73% to 46. 9%, which was similar to the inhibition rate of 5-Fu ranged from 12.49% to 38.92% ( P= 0. 351) . The inhibition rate of IFN-γ in two experiments was smaller than MMC and 5-Fu ( P < 0.05).Conclusion: IFN-γ has bifunctional effect (both enhancement and inhibition) on proliferation of cultured HTCF. The antiproliferative effect of IFN-γ was weaker than MMC and 5-Fu. Further study has to be carried out to document the inhibition of scar formation of filtration bleb by IFN-γ and the molecular mechanisms of its bifunctional effect on HTCF proliferation. Eye Science 2000; 16: 43~ 47.

  7. Bifunctional Effect of Human IFN-γ on Cultured Human Fibroblasts from Tenon‘s Capsule

    Institute of Scientific and Technical Information of China (English)

    YanGuo; JianGe; 等

    2002-01-01

    Purpose:To study the effect of human IFN-γ on in ivtro cultured human fibroblasts from Tenon's capsule.Materials and methods:The effect of different concentrations of human IFN-γand mitomycin-C (MMC),5-fluorouracil(5-Fu) on cultured human Tenon's capsule fibroblasts(HTCF) was measured using a MTT[3-(4,5-dimethylthiazo-2-yI)]-2,5-diphenylterazolium bromide;Thiazolyl blue) colorimetric assay.The results were analyzed using ANOVA of the statistical package for social sciences (SPSS) 9.0 version.The difference was considered to be significant if P<0.05.Results:The effects of MMC and 5-Fu on the growth of HTCF were negative,while the effects of IFN-γon the growth of HTCF were both negative(102-104 units/ml in two experiments)and positive(106,105,10 units /ml in two experiments).The inhibition rate of MMC ranged from 5.73% to 46.9% ,which was similar to the inhibition rate of 5-Fu ranged from 12.49% to 38.92%(P=0.351).The inhibition rate of IFN-γ in two experiments was smaller than MMC and 5-Fu (P<0.05).Conclusion: IFN-γ has bifunctional effect (both enhancement and inhibition)on proliferation of cultured HTCF.The antiproliferative effect of IFN-γ was weaker than MMC and 5-Fu.Further study has to be carried out to document theinhibition of scar formation of filtration bleb by IFN-γ and the molecular mechanisms of its bifunctional effect on HTCF proliferation.Eye Science 2000;16:43-47.

  8. 硅烷偶联剂改性纳米二氧化钛并接枝丙烯腈的机理%Mechanism of nano-TiO2 modified silane coupling agent and grafting acrylonitrile

    Institute of Scientific and Technical Information of China (English)

    王雅珍; 陈国力; 岳成娥; 赵宇; 何子健

    2015-01-01

    主要研究了硅烷偶联剂(KH-560)改性纳米二氧化钛(TiO2)制备TiO2(KH-560)以及TiO2(KH-560)与丙烯腈(AN)接枝聚合生成TiO2(KH-560)-g-AN的反应机理。通过傅里叶变换红外(FT-IR)分析确定了TiO2(KH-560)和TiO2(KH-560)-g-AN的官能团结构。通过X射线光电子能谱(XPS)分析,由TiO2(KH-560)中的氧元素和碳元素结合能的微小变化,引起 C1s、O1s 化学环境的变化,来确定 TiO2(KH-560)的结构;由 TiO2(KH-560)-g-AN的氧元素、碳元素和氮元素的结合能微小变化引起 C1s、O1s、N1s 化学环境的变化,从而确定了TiO2(KH-560)-g-AN的结构。结合FTIR和XPS两者的分析,最终确定TiO2(KH-560)-g-AN的反应机理。%The reaction mechanism of nano-titanium dioxide (TiO2) modified with the silane coupling agent (KH-560) grafted with acrylonitrile(AN) to produce TiO2(KH-560)-g-AN was studied. Functional group structures of TiO2 (KH-560) and TiO2(KH-560)-g-AN were determined by Fourier transform infrared (FT-IR) analysis. The results of X-ray photoelectron spectroscopy (XPS) analysis show that chemical environment of C1s,O1s in TiO2(KH-560) are caused by slight variations of oxygen and carbon element binding energy in TiO2(KH-560). So the structure of TiO2(KH-560) is determined. Chemical environment of C1s,O1s,and N1s in TiO2(KH-560)-g-AN are caused by slight variations of oxygen,carbon,and nitrogen element binding energy in TiO2(KH-560)-g-AN. So the structure of TiO2(KH-560)-g-AN is determined. The graft polymerization mechanism of TiO2(KH-560) and AN is determined ultimately by the analysis of both FT-IR and XPS.

  9. Purification, crystallization and preliminary X-ray crystallographic analysis of rice bifunctional α-amylase/subtilisin inhibitor from Oryza sativa

    International Nuclear Information System (INIS)

    The crystallization of rice α-amylase/subtilisin bifunctional inhibitor is reported. Rice bifunctional α-amylase/subtilisin inhibitor (RASI) can inhibit both α-amylase from larvae of the red flour beetle (Tribolium castaneum) and subtilisin from Bacillus subtilis. The synthesis of RASI is up-regulated during the late milky stage in developing seeds. The 8.9 kDa molecular-weight RASI from rice has been crystallized using the hanging-drop vapour-diffusion method. According to 1.81 Å resolution X-ray diffraction data from rice RASI crystals, the crystal belongs to space group P21212, with unit-cell parameters a = 79.99, b = 62.95, c = 66.70 Å. Preliminary analysis indicates two RASI molecules in an asymmetric unit with a solvent content of 44%

  10. Dual-Doped Molybdenum Trioxide Nanowires: A Bifunctional Anode for Fiber-Shaped Asymmetric Supercapacitors and Microbial Fuel Cells.

    Science.gov (United States)

    Yu, Minghao; Cheng, Xinyu; Zeng, Yinxiang; Wang, Zilong; Tong, Yexiang; Lu, Xihong; Yang, Shihe

    2016-06-01

    A novel in situ N and low-valence-state Mo dual doping strategy was employed to significantly improve the conductivity, active-site accessibility, and electrochemical stability of MoO3 , drastically boosting its electrochemical properties. Consequently, our optimized N-MoO3-x nanowires exhibited exceptional performances as a bifunctional anode material for both fiber-shaped asymmetric supercapacitors (ASCs) and microbial fuel cells (MFCs). The flexible fiber-shaped ASC and MFC device based on the N-MoO3-x anode could deliver an unprecedentedly high energy density of 2.29 mWh cm(-3) and a remarkable power density of 0.76 μW cm(-1) , respectively. Such a bifunctional fiber-shaped N-MoO3-x electrode opens the way to integrate the electricity generation and storage for self-powered sources. PMID:27097987

  11. Dynamics of tropomyosin in muscle fibers as monitored by saturation transfer EPR of bi-functional probe.

    Directory of Open Access Journals (Sweden)

    Roni F Rayes

    Full Text Available The dynamics of four regions of tropomyosin was assessed using saturation transfer electron paramagnetic resonance in the muscle fiber. In order to fully immobilize the spin probe on the surface of tropomyosin, a bi-functional spin label was attached to i,i+4 positions via cysteine mutagenesis. The dynamics of bi-functionally labeled tropomyosin mutants decreased by three orders of magnitude when reconstituted into "ghost muscle fibers". The rates of motion varied along the length of tropomyosin with the C-terminus position 268/272 being one order of magnitude slower then N-terminal domain or the center of the molecule. Introduction of troponin decreases the dynamics of all four sites in the muscle fiber, but there was no significant effect upon addition of calcium or myosin subfragment-1.

  12. Synthesis and Characterization of Bifunctional Organic-Glasses Based on Diphenylhydrazone and Barbituric Acid Derivative for Photorefractive Application

    International Nuclear Information System (INIS)

    A series of amorphous molecules that possess both photoconductive and electro-optic properties was synthesized in order to investigate photorefractive properties of bifunctional organic-glasses. Diethylaminobenzaldehyde- diphenylhydrazone was covalently attached to 5-(4-diethylamino-benzylidene)-1,3-dimethylpyrimidine- 2,4,6-trione through a flexible alkyl chain (3, 4, 5, 6 and 10 carbons) containing two ether linkages. The longer linkage not only lowered the glass transition temperature (Tg) of the molecules, but also allowed faster orientation of the chromophore. To examine the photorefractive properties, a 50 μm-thick film was prepared from the mixture of a bifunctional molecule, butyl benzyl phthalate, and C60. The photoconductivity of this composite was as high as 8.01 x 10-12 S/cm at 60 V/μm, and the maximum diffraction efficiency (ηmax) of 50 μm-thick film was about 5% at 80 V/μm

  13. Crystallization and preliminary X-ray analysis of a bifunctional catalase-phenol oxidase from Scytalidium thermophilum

    International Nuclear Information System (INIS)

    The bifunctional enzyme catalase-phenol oxidase from S. thermophilum was crystallized by the hanging-drop vapour-diffusion method in space group P21 and diffraction data were collected to 2.8 Å resolution. Catalase-phenol oxidase from Scytalidium thermophilum is a bifunctional enzyme: its major activity is the catalase-mediated decomposition of hydrogen peroxide, but it also catalyzes phenol oxidation. To understand the structural basis of this dual functionality, the enzyme, which has been shown to be a tetramer in solution, has been purified by anion-exchange and gel-filtration chromatography and has been crystallized using the hanging-drop vapour-diffusion technique. Streak-seeding was used to obtain larger crystals suitable for X-ray analysis. Diffraction data were collected to 2.8 Å resolution at the Daresbury Synchrotron Radiation Source. The crystals belonged to space group P21 and contained one tetramer per asymmetric unit

  14. N,P-Codoped Carbon Networks as Efficient Metal-free Bifunctional Catalysts for Oxygen Reduction and Hydrogen Evolution Reactions.

    Science.gov (United States)

    Zhang, Jintao; Qu, Liangti; Shi, Gaoquan; Liu, Jiangyong; Chen, Jianfeng; Dai, Liming

    2016-02-01

    The high cost and scarcity of noble metal catalysts, such as Pt, have hindered the hydrogen production from electrochemical water splitting, the oxygen reduction in fuel cells and batteries. Herein, we developed a simple template-free approach to three-dimensional porous carbon networks codoped with nitrogen and phosphorus by pyrolysis of a supermolecular aggregate of self-assembled melamine, phytic acid, and graphene oxide (MPSA/GO). The pyrolyzed MPSA/GO acted as the first metal-free bifunctional catalyst with high activities for both oxygen reduction and hydrogen evolution. Zn-air batteries with the pyrolyzed MPSA/GO air electrode showed a high peak power density (310 W g(-1) ) and an excellent durability. Thus, the pyrolyzed MPSA/GO is a promising bifunctional catalyst for renewable energy technologies, particularly regenerative fuel cells. PMID:26709954

  15. Hydrocarbon fuel synthesis from sorbitol over bifunctional catalysts: Association of tungstated titania with platinum, palladium or iridium

    OpenAIRE

    Vilcocq, Léa; Cabiac, Amandine; Especel, Catherine; Lacombe, Sylvie; Duprez, Daniel

    2015-01-01

    To selectively transform sorbitol into hydrocarbons in aqueous phase, new bifunctional catalytic systems are designed by associating a hydrogenating metallic catalyst (M/ZrO2, M = Pt, Ir or Pd) and a dehydratingacidic catalyst (TiO2–WOx) in a mechanical mixture. Zirconium oxide was chosen as support because ithas virtually no dehydration activity and gives a good stability to the metal in water. This stability isevaluated through several characterizations before and after contact with the aqu...

  16. The bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provides a tool for molecular and biotechnology applications

    OpenAIRE

    Tiedtke Arno; Bockau Ulrike; Herrmann Lutz; Hartmann Marcus WW; Weide Thomas

    2006-01-01

    Abstract Background Dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme. Results Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first aspect of the presented work relates to dest...

  17. Vanadium nanobelts coated nickel foam 3D bifunctional electrode with excellent catalytic activity and stability for water electrolysis

    Science.gov (United States)

    Yu, Yu; Li, Pei; Wang, Xiaofang; Gao, Wenyu; Shen, Zongxu; Zhu, Yanan; Yang, Shuliang; Song, Weiguo; Ding, Kejian

    2016-05-01

    Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity.Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity. Electronic supplementary information (ESI) available: More SEM, TEM images, XRD patterns, LSV curves, XPS spectra. See DOI: 10.1039/c6nr02395a

  18. Enhanced bifunctional activity of LaNiO3-based gas diffusion electrodes for regenerative fuel cells

    OpenAIRE

    Silva, R A; Soares, C. O.; Carvalho, M. D.; C. M. Rangel; Pereira, M. I. da Silva

    2013-01-01

    Perovskites are of great interest when searching replacements for precious metals as catalyst for bifunctional oxygen electrodes involving the oxygen evolution(OER) and oxygen reduction reaction (ORR) as is the case of regenerative fuel cells. In this work a full electrochemical study on the electrochemical properties of gas diffusion electrodes (GDEs) using LaNiO3-based catalysts, conducted in alkaline media, led to a study of cyclability and durability. The incorporation of GDEs in a low po...

  19. The Role of the Methyltransferase Domain of Bifunctional Restriction Enzyme RM.BpuSI in Cleavage Activity

    OpenAIRE

    Arthur Sarrade-Loucheur; Shuang-yong Xu; Siu-Hong Chan

    2013-01-01

    Restriction enzyme (REase) RM.BpuSI can be described as a Type IIS/C/G REase for its cleavage site outside of the recognition sequence (Type IIS), bifunctional polypeptide possessing both methyltransferase (MTase) and endonuclease activities (Type IIC) and endonuclease activity stimulated by S-adenosyl-L-methionine (SAM) (Type IIG). The stimulatory effect of SAM on cleavage activity presents a major paradox: a co-factor of the MTase activity that renders the substrate unsusceptible to cleavag...

  20. L-Threonine-derived novel bifunctional phosphine-sulfonamide catalyst-promoted enantioselective aza-morita-Baylis-Hillman reaction

    KAUST Repository

    Zhong, Fangrui

    2011-03-18

    A series of novel bifunctional phosphine-sulfonamide organic catalysts were designed and readily prepared from natural amino acids, and they were utilized to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions. l-Threonine-derived phosphine-sulfonamide 9b was found to be the most efficient catalyst, affording the desired aza-MBH adducts in high yields and with excellent enantioselectivities. © 2011 American Chemical Society.

  1. Agent Chameleons: Virtual Agents Real Intelligence

    OpenAIRE

    O'Hare, Gregory; Duffy, Brian; Schoen-Phelan, Bianca; Martin, Alan; Bradley, John

    2003-01-01

    Agent Chameleons provides virtual agents powered by real intelligence, delivering next generation autonomic entities that can seamlessly migrate, mutate and evolve on their journey between and within physical and digital information spaces.

  2. The Preparation and Mechanical Properties of Aluminate Coupling Agent Modified Micro-Crystal Muscovite/PVC Composite Materials%铝酸酯偶联剂表面改性微晶白云母/PVC复合材料的制备及力学性能

    Institute of Scientific and Technical Information of China (English)

    周世一; 林金辉; 雷景新

    2012-01-01

    以中国川西地区发现的一种新型矿物资源微晶白云母为原料,以铝酸酯偶联剂F-1为改性剂,对微晶白云母进行改性研究,并将表面改性后的微晶白云母加入聚氯乙烯(PVC)中制得微晶白云母/PVC复合材料。测试了改性粉体与石蜡体系的黏度及复合材料的力学性能,并采用扫描电子显微镜表征了其微观结构。结果表明,铝酸酯偶联剂F-1能有效改善微晶白云母表面与有机物质的界面结合,并且将经铝酸酯偶联剂F-1改性的微晶白云母加入PVC基体中能提高微晶白云母/PVC复合材料的力学性能,当铝酸酯偶联剂的用量为1.0%(质量分数,下同)、微晶白云母用量为15%时,微晶白云母/PVC复合材料的力学性能最好。%The micro-crystal muscovite is a new kind of minerals found in west Sichuan area. The surface of the micro-crystal muscovite powders was modified by aluminate coupling agent F-1 and was added into plasticized poly (vinyl chloride) (PVC). The viscosity of the modified micro-crystal muscovite powders/paraffin was tested. The structure and mechanical properties of micro-crystal muscovite/PVC composite were studied by SEM and tesl:er. The results show that aluminate coupling agent F-I can effectively improve the interracial bond strength of micro-crystal muscovite and the organic matter, and the micro-crystal muscovite modified by aluminate coupling agent F-1 can improve mechanical properties of PVC. When aluminate coupling agent F-1 is 1.0 % and the micro-crystal muscovite content is 15 %, the mechanical properties of micro-crystal museovite/PVC composites materials are great.

  3. Study of the effect of ionizing radiation on composites of wood flour in polypropylene matrix using barium titanate as coupling agent; Estudo do efeito da radiacao ionizante em compositos de polipropileno/po de madeira usando titanato de bario como agente de acoplagem

    Energy Technology Data Exchange (ETDEWEB)

    Ulloa, Maritza Eliza Perez

    2007-07-01

    The purpose of this work was to study the effects of ionizing radiation on the properties of wood flour composites in polypropylene matrix, using barium titanate as a coupling agent and the reactive monomer tripropylene glycol diacrylate (TPDGA). An electron accelerator was used in the study as the radiation source. The physical properties of virgin compounds and of the polypropylene/wood flour composite, with and without barium titanate and TPDGA addition, were investigated. The composites were developed from the load treatment, which first consisted of incorporating additives to the wood flour reinforcement and after that, the fusion process of polypropylene and composite mixing in a 'calander'. Subsequently, the samples to be irradiated and submitted to thermal and mechanical assays were molded by injection. The mechanical properties (hardness, impact resistance and molten fluidity index (MFI)), as well as the thermal properties (HDT and Vicat) of the composites were determined. The investigated compositions consisted of polypropylene/wood flour, polypropylene/wood flour with barium titanate and polypropylene/wood flour with barium titanate and TPDGA, using different wood flour concentrations of 10 por cent, 15 por cent and 20 por cent in the polypropylene matrix. The samples were separated in groups and irradiated to doses of 10 kGy and 20 kGy in the samples of the essays of traction. Besides these doses, it was also used doses of 15 kGy and 25 kGy to be observed the behavior of the sample of the sample due to the increase of the radiation. These doses were chosen to show that with low doses the composite material presents reticulation, what represents a viable commercial option. There was a reduction of the flow rate for the composites containing wood flour, being this reduction more effective in the presence of TiBa. The superficial treatment using TPDGA monomer influence in the composite samples because it acted as a plastic additive becoming the

  4. Bifunctional chimeric SuperCD suicide gene -YCD: YUPRT fusion is highly effective in a rat hepatoma model

    Institute of Scientific and Technical Information of China (English)

    Florian Graepler; Ulrike A Lauer; Reinhard Vonthein; Michael Gregor; Sorin Armeanu; Michael Bitzer; Ulrich M. Lauer; Marie-Luise Lemken; Wolfgang A Wybranietz; Ulrike Schmidt; Irina Smirnow; Christine D Groβ; Martin Spiegel; Andrea Schenk; Hansj(o)rg Graf

    2005-01-01

    AIM: To investigate the effects of catalytically superior gene-directed enzyme prodrug therapy systems on a rat hepatoma model.METHODS: To increase hepatoma cell chemosensitivity for the prodrug 5-fluorocytosine (5-FC), we generated a chimeric bifunctional SuperCD suicide gene, a fusion of the yeast cytosine deaminase (YCD) and the yeast uracil phosphoribosyltransferase (YUPRT) gene.RESULTS: In vitro stably transduced Morris rat hepatoma cells (MH) expressing the bifunctional SuperCD suicide gene (MH SuperCD) showed a clearly marked enhancement in cell killing when incubated with 5-FC as compared with MH ceils stably expressing YCD solely (MH YCD) or the cytosine deaminase gene of bacterial origin(MH BCD), respectively. In vivo, MH SuperCD tumors implanted both subcutaneously as well as orthotopically into the livers of syngeneic ACI rats demonstrated significant tumor regressions (P<0.01) under both high dose as well as low dose systemic 5-FC application,whereas MH tumors without transgene expression (MH naive) showed rapid progression. For the first time, an order of in vivo suicide gene effectiveness (SuperCD>>YCD > > BCD > > > negative control) was defi ned as a result of a directin vivo comparison of all three suicide genes.CONCLUSION: Bifunctional SuperCD suicide gene expression is highly effective in a rat hepatoma model,thereby significantly improving both the therapeutic index and the efficacy of hepatocellular carcinoma killing by fluorocytosine.

  5. Gold nanoparticle immobilization on ZnO nanorods via bi-functional monolayers: A facile method to tune interface properties

    Science.gov (United States)

    Jayaraman, Sundaramurthy; Suresh Kumar, P.; Mangalaraj, D.; Dharmarajan, Rajarathnam; Ramakrishna, Seeram; P Srinivasan, M.

    2015-11-01

    We demonstrated the functionalization of one dimensional (1-D) zinc oxide nanorods (ZnO NRs) using bi-functional organic molecules to create hybrid structures with surface functionalities and tuneable organic/inorganic interface. Bi-functional molecules with carboxylic acid, thiol and silane end groups and amine termination had been employed to functionalize the NRs by forming carboxylate, thiolate and hydroxylation bonds, respectively, with ZnO. The surface textures of NRs were preserved even after functionalization. The functionalized NRs were decorated with gold nanoparticles (AuNPs) and the hybrid structures exhibited a quenched blue shift ultraviolet emission which depended on the distance between the ZnO surface and the AuNPs. The NR functionalization with bi-functional molecules and decoration of NPs, and surface morphologies were analyzed using x-ray photoelectron spectroscopy, field emission scanning electron microscopy and transmission electron spectroscopy. These hybrid structures can play a vital role in tuning the interface properties and have potential applications in future photovoltaics, chemical sensors, biomarkers, and wavelength based biosensors.

  6. NHS-MAS3: a bifunctional chelator alternative to NHS-MAG3

    International Nuclear Information System (INIS)

    This laboratory uses an N-hydroxysuccinimide derivative of S-acetylmercaptoacetyltriglycine (NHS-MAG3) to conjugate amines for subsequent labeling with 99mTc. However, the synthesis from triglycerine is general and not restricted to this tripeptide. We had earlier selected a small number of alternative tripeptides and synthesized the corresponding NHS derivatives. Each was then evaluated in a search for bifunctional chelators with properties superior to NHS-MAG3, such as lower serum protein binding or improved stability to cysteine challenge. Based on these preliminary results, NHS-S-acetylmercaptoacetyltriserine (NHS-MAS3) was selected for further investigation. We have now conjugated this bifunctional chelator to biocytin and to an amine-derivatized peptide nucleic acid (PNA). Both carriers were also conjugated with NHS-MAG3 under identical conditions and all were labeled with 99mTc at neutral pH and at boiling temperature while the conjugated PNAs were radiolabelled at neutral pH and at room temperature. Regardless of the chelator, reverse phase HPLC radiochromatograms of the labeled biotins and PNAs after purification showed a single peak. However, by size exclusion HPLC, the radiochromatograms always showed several peaks even after purification, but the MAS3 radiochromatograms were less complicated. For biotin and PNA both, radiolabeling via MAS3 showed improved 99mTc stability in 37 deg. C serum and in cysteine solution. The four preparations were administered to mice implanted in one thigh with avidin beads (biotins) or complementary PNA beads (PNAs). At 5 h post-administration, no significant differences were observed in the targeting of PNA beads between the two chelators, however the target thigh/normal thigh ratio was significantly higher for MAS3-biotin compared to MAG3-biotin. We conclude that labeling biocytin and amine-derivatized PNA with NHS-MAS3 compared to NHS-MAG3 provides simpler radiochromatographic profiles, improved stability of the label in

  7. Bi-functional prodrugs of 5-aminolevulinic acid and butyric acid increase erythropoiesis in anemic mice in an erythropoietin-independent manner.

    Science.gov (United States)

    Rephaeli, Ada; Tarasenko, Nataly; Fibach, Eitan; Rozic, Gabriela; Lubin, Ido; Lipovetsky, Julia; Furman, Svetlana; Malik, Zvi; Nudelman, Abraham

    2016-08-25

    Anemia is a major cause of morbidity and mortality worldwide resulting from a wide variety of pathological conditions. In severe cases it is treated by blood transfusions or injection of erythroid stimulating agents, e.g., erythropoietin (Epo), which can be associated with serious adverse effects. Therefore, there is a need to develop new treatment modalities. We recently reported that treatment of erythroleukemic cells with the novel the bi-functional prodrugs of 5-aminolevulinic acid (ALA) and butyric acid (BA), AN233 and AN908, enhanced hemoglobin (Hb) synthesis to a substantially higher level than did ALA and BA individually or their mixture. Herein, we describe that these prodrugs when given orally to mice induced histone deacetylase inhibition in the kidneys, bone marrow and spleen, thus, indicating good penetrability to the tissues. In mice where anemia was chemically induced, treatment with the prodrugs increased the Hb, the number of red blood cells (RBCs) and the percentage of reticulocytes to normal levels. The prodrugs had no adverse effects even after repeated treatment at 100-200mg/kg for 50days. The lack of increased levels of Epo in the blood of mice that were treated with the prodrugs suggests that AN233 and AN908 affected the Hb and RBC levels in an Epo-independent manner. Taken together with our previous studies, we propose that the prodrugs increase globin expression by BA inhibition of histone deacetylase and elevation heme synthesis by ALA. These results support an Epo-independent approach for treating anemia with these prodrugs. PMID:27283485

  8. Standardization of methodology to derivatization and radiolabeling of the anti-CD20 monoclonal antibody from bifunctional chelator DOTA-NHS-Ester

    International Nuclear Information System (INIS)

    Lymphomas are cancers of the lymphatic system, being the most common the non-Hodgkin lymphoma (NHL). The Radioimmunotherapy (RIT), that increase the cytotoxic effect of monoclonal antibodies (mAb), therefore labeling these Mab with different radioisotopes. RIT combines the specificity of the antibody and the toxicity of the radionuclides. The mAb anti-CD20 is used for treatment of relapse or refractory NHL. The labeling of anti- CD20 with 177Lu, requires a bifunctional chelating agent that is designed to make a 'connect bridge' between the mAb and the radionuclide. The incorporation of the chelating group in mAb structure is called derivatization. The aim of this work is to study the derivatization of anti-CD20 antibody with DOTA-NHS-ester chelating group and labeling parameters to produce 177Lu-DOTA-Anti CD20. Five milligrams of anti-CD20 were purified by dialysis against phosphate buffer pH 8.0 and derivatized with DOTA-NHS-ester in 1:250, 1:500 and 1:1000 molar ratios. The reaction was conducted for 1 hour in gently mixing at room temperature and remained under refrigeration for 48 hours. The reaction mixture was purified in gel column Sephadex G-50 ; the aliquots that presented greater protein concentration, were mixed and concentrated. The purified antibody conjugated was added to 111-185MBq (3-5mCi) of 177LuCl3 diluted in 0.4 M acetate buffer pH 5.5. Radiochemical purity was less than 95% in all the molar ratios, indicating necessity of the purification after the labeling. The mAb derivatized showed stable when stored for to 1 month to 4 deg C and 4 days at -20 deg C. (author)

  9. The ERAD inhibitor Eeyarestatin I is a bifunctional compound with a membrane-binding domain and a p97/VCP inhibitory group.

    Directory of Open Access Journals (Sweden)

    Qiuyan Wang

    Full Text Available BACKGROUND: Protein homeostasis in the endoplasmic reticulum (ER has recently emerged as a therapeutic target for cancer treatment. Disruption of ER homeostasis results in ER stress, which is a major cause of cell death in cells exposed to the proteasome inhibitor Bortezomib, an anti-cancer drug approved for treatment of multiple myeloma and Mantle cell lymphoma. We recently reported that the ERAD inhibitor Eeyarestatin I (EerI also disturbs ER homeostasis and has anti-cancer activities resembling that of Bortezomib. METHODOLOGY AND PRINCIPAL FINDINGS: Here we developed in vitro binding and cell-based functional assays to demonstrate that a nitrofuran-containing (NFC group in EerI is the functional domain responsible for the cytotoxicity. Using both SPR and pull down assays, we show that EerI directly binds the p97 ATPase, an essential component of the ERAD machinery, via the NFC domain. An aromatic domain in EerI, although not required for p97 interaction, can localize EerI to the ER membrane, which improves its target specificity. Substitution of the aromatic module with another benzene-containing domain that maintains membrane localization generates a structurally distinct compound that nonetheless has similar biologic activities as EerI. CONCLUSIONS AND SIGNIFICANCE: Our findings reveal a class of bifunctional chemical agents that can preferentially inhibit membrane-bound p97 to disrupt ER homeostasis and to induce tumor cell death. These results also suggest that the AAA ATPase p97 may be a potential drug target for cancer therapeutics.

  10. Bifunctional silica nanoparticles for the exploration of biofilms of Pseudomonas aeruginosa.

    Science.gov (United States)

    Mauline, L; Gressier, M; Roques, C; Hammer, P; Ribeiro, S J L; Caiut, J M A; Menu, M-J

    2013-01-01

    Luminescent silica nanoparticles are frequently employed for biotechnology applications mainly because of their easy functionalization, photo-stability, and biocompatibility. Bifunctional silica nanoparticles (BSNPs) are described here as new efficient tools for investigating complex biological systems such as biofilms. Photoluminescence is brought about by the incorporation of a silylated ruthenium(II) complex. The surface properties of the silica particles were designed by reaction with amino-organosilanes, quaternary ammonium-organosilanes, carboxylate-organosilanes and hexamethyldisilazane. BSNPs were characterized extensively by DRIFT, (13)C and (29)Si solid state NMR, XPS, and photoluminescence. Zeta potential and contact angle measurements exhibited various surface properties (hydrophilic/hydrophobic balance and electric charge) according to the functional groups. Confocal laser scanning microscopy (CLSM) measurements showed that the spatial distribution of these nanoparticles inside a biofilm of Pseudomonas aeruginosa PAO1 depends more on their hydrophilic/hydrophobic characteristics than on their size. CLSM observations using two nanosized particles (25 and 68 nm) suggest that narrow diffusion paths exist through the extracellular polymeric substances matrix. PMID:23805884

  11. Antimutagenic activities of two suspected anticarcinogenic bifunctional organoiron seleno-terephthalate derivatives.

    Science.gov (United States)

    Maslat, Ahmed O; Jibril, Ibrahim; Mizyed, Shehdeh

    2010-07-01

    Two newly bifunctional organoiron seleno-terephthalate derivatives (S1 and S2) were synthesized as potential anticarcinogenic compounds. In a previous study, they were found to have antibacterial and/or antifungal activity, while they did not show any mutagenic action. Such compounds were investigated in the present study for their antimutagenic activity. Sodium azide, hydrogen peroxide, and 4-nitro-o-phenylenediamine, as known mutagens for strains TA100, TA102, and TA98 of Salmonella typhimurium, respectively, were used. Both (S1 and S2) compounds showed a strong antimutagenic action of >98% against sodium azide, >70% against hydrogen peroxide, and >65% activity against 4-nitro-o-phenylenediamine. Bearing in mind the strong correlation between mutagenicity and carcinogenicity, the above compounds can be considered as potentially promising anticarcinogens. Therefore, the present results are very encouraging to investigate the above compounds for other biological activities, including their evaluation as anticarcinogens. A suggested mechanism for the antimutagenicity of the tested compounds is presented. PMID:20462347

  12. Bifunctional nanoparticles for surface-enhanced Raman spectroscopy-based leukemia biomarker detection

    Science.gov (United States)

    Mehn, Dora; Morasso, Carlo; Vanna, Renzo; Schiumarini, Domitilla; Bedoni, Marzia; Ciceri, Fabio; Gramatica, Furio

    2014-03-01

    The Wilms tumor gene (WT1) is a biomarker overexpressed in more than 90% of acute myeloid leukemia patients. Fast and sensitive detection of the WT1 in blood samples would allow monitoring of the minimal residual disease during clinical remission and would permit early detection of a potential relapse in acute myeloid leukemia. In this work, Surface Enhanced Raman Spectroscopy (SERS) based detection of the WT1 sequence using bifunctional, magnetic core - gold shell nanoparticles is presented. The classical co-precipitation method was applied to generate magnetic nanoparticles which were coated with a gold shell after modification with aminopropyltriethoxy silane and subsequent deposition of gold nanoparticle seeds. Simple hydroquinone based reduction procedure was applied for the shell growing in water based reaction mixture at room temperature. Thiolated ssDNA probes of the WT1 sequence were immobilized as capture oligonucleotides on the gold surface. Malachite green was applied both for testing the amplification performance of the core-shell colloidal SERS substrate and also as label dye of the target DNA sequence. The SERS enhancer efficacy of the core-shell nanomaterial was compared with the efficacy of classical spherical gold particles produced using the conventional citrate reduction method. The core-shell particles were found not only to provide an opportunity for facile separation in a heterogeneous reaction system but also to be superior regarding robustness as SERS enhancers.

  13. Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

    Energy Technology Data Exchange (ETDEWEB)

    Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore)

    2012-06-15

    Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

  14. Directed assembly of bifunctional silica-iron oxide nanocomposite with open shell structure.

    Science.gov (United States)

    Che, Hui Xin; Yeap, Swee Pin; Osman, Mohamed Syazwan; Ahmad, Abdul Latif; Lim, JitKang

    2014-10-01

    The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure. PMID:25198872

  15. The rigid bi-functional sail, new concept concerning the reduction of the drag of ships

    Science.gov (United States)

    Țicu, I.; Popa, I.; Ristea, M.

    2015-11-01

    The policy of the European Union in the energy field, for the period to follow until 2020, is based on three fundamental objectives: sustainability, competitiveness and safety in energy supply. The “Energy - Climate Changes” program sets out a number of objectives for the EU for the year 2020, known as the “20-20-20 objectives”, namely: the reduction of greenhouse gas emissions by at least 20% from the level of those of 1990, a 20% increase in the share of renewable energy sources out of the total energy consumption as well as a target of 10% biofuels in the transports energy consumption. In this context, in order to produce or save a part of the propulsive power produced by the main propulsion machinery, by burning fossil fuels, we suggest the equipping of vessels designed for maritime transport with a bi-functional rigid sail. We consider that this device may have both the role of trapping wind energy and the role of acting as a deflector for reducing the resistance of the vessel's proceeding through the water by conveniently using the bow air current, as a result of the vessel's heading through the water with significant advantage in reducing the energy consumption for propulsion insurance.

  16. Carboxylation and Decarboxylation of Aluminum Oxide Nanoparticles Using Bifunctional Carboxylic Acids and Octylamine

    Directory of Open Access Journals (Sweden)

    Shirin Alexander

    2016-01-01

    Full Text Available The carboxylation of alumina nanoparticles (NPs, with bifunctional carboxylic acids, provides molecular anchors that are used for building more complexed structures via either physisorption or chemisorption. Colloidal suspensions of the NPs may be prepared by covalently bonding a series of carboxylic acids with secondary functional groups (HO2C-R-X to the surface of the NPs: lysine (X = NH2, p-hydroxybenzoic acid (X = OH, fumaric acid (X = CO2H, and 4-formylbenzoic acid (X = C(OH. Subsequent reaction with octylamine at either 25°C or 70°C was investigated. Fourier transform IR-attenuated reflectance spectroscopy (FTIR-ATR, thermogravimetric analysis (TGA, and scanning electron microscopy (SEM along with energy dispersive X-ray (EDX analysis were used to characterize the bifunctionalized monolayers and/or multilayer corona surrounding the alumina NPs and investigate the reaction mechanism of octylamine with the functional groups (X of the NPs. Except for the fumaric functionalized NPs, addition of octylamine to the functionalized NPs leads to removal of excess carboxylic acid corona from the surface via an amide formation. The extent of the multilayer is dependent on the strength of the acid⋯acid interaction.

  17. Mechanism of tetralin ring opening and contraction over bifunctional Ir/SiO₂-Al₂O₃ Catalysts.

    Science.gov (United States)

    Piccolo, Laurent; Nassreddine, Salim; Toussaint, Guy; Geantet, Christophe

    2012-09-01

    The development of cleaner fuels from conventional resources requires the finding of new hydrotreatment processes able to improve the combustion performances of fuels and limit undesirable emissions. In the context of gas oil upgrading by selective ring opening, we have investigated the hydroconversion of tetralin over iridium nanoparticles supported on amorphous silica-alumina. The conversion of tetralin leads to hydrogenation, ring-contraction, and ring-opening products. The selectivity to ring-opening/-contraction products (ROCPs) increases linearly with the acid-metal site ratio and can be tuned by modifying the metal loading, the metal nanoparticle size, or the support composition. From the combination of catalytic tests at variable conversion and the products identification by two-dimensional gas chromatography, a mechanistic reaction scheme has been established. Aromatic ROCPs are formed through purely acidic steps, whereas the formation of saturated ROCPs mostly involves bifunctional reaction steps. Iridium-catalyzed hydrogenolysis appears to be a minor pathway with respect to iridium-catalyzed hydrogenation and Brønsted acid catalyzed isomerization. PMID:22949005

  18. Fe3O4 and CdS based bifunctional core–shell nanostructure

    International Nuclear Information System (INIS)

    Highlights: ► First report on a room temperature aqueous process for growth of a hybrid core shell nanostructure containing a magnetic core and a semiconducting shell. ► Formation of distinct core shell nanostructure revealed by high resolution transmission electron microscopy. ► A bifunctional nature combining magnetic as well as photoresponce for the as synthesised core shell nanostructures demonstrated. ► A tendency towards self organisation of the core–shell nanostructure. ► Possible applications including purification and isolation of biological materials, drug delivery system, bio-labels, spintronics, etc. -- Abstract: A room temperature solution process for synthesis of Fe3O4 nanoparticles and their hybrid core shell nanostructures using CdS as the shell material has been described. The as grown particles have been characterised using XRD, Rietveld refinement, high resolution transmission electron microscopy, atomic force microscopy, superconducting quantum interference device, optical absorbance and photoluminescence spectroscopy. A superparamagnetic response revealed from the magnetisation measurements of the as synthesised magnetite nanoparticles was retained even after the growth of the CdS shell. From luminescence and high resolution atomic force microscopy measurements, it is shown that the core–shell structures advantageously combine magnetic as well as fluorescence response with a tendency towards self-organization.

  19. Bifunctional separator as a polysulfide mediator for highly stable Li-S batteries

    KAUST Repository

    Abbas, Syed Ali

    2016-05-24

    The shuttling process involving lithium polysulfides is one of the major factors responsible for the degradation in capacity of lithium–sulfur batteries (LSBs). Herein, we demonstrate a novel and simple strategy—using a bifunctional separator, prepared by spraying poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on pristine separator—to obtain long-cycle LSBs. The negatively charged SO3– groups present in PSS act as an electrostatic shield for soluble lithium polysulfides through mutual coulombic repulsion, whereas PEDOT provides chemical interactions with insoluble polysulfides (Li2S, Li2S2). The dual shielding effect can provide an efficient protection from the shuttling phenomenon by confining lithium polysulfides to the cathode side of the battery. Moreover, coating with PEDOT:PSS transforms the surface of the separator from hydrophobic to hydrophilic, thereby improving the electrochemical performance. We observed an ultralow decay of 0.0364% per cycle when we ran the battery for 1000 cycles at 0.25 C—far superior to that of the pristine separator and one of the lowest recorded values reported at a low current density. We examined the versatility of our separator by preparing a flexible battery that functioned well under various stress conditions; it displayed flawless performance. Accordingly, this economical and simple strategy appears to be an ideal platform for commercialization of LSBs.

  20. Cobalt Phosphide Hollow Polyhedron as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Hydrogen and Oxygen.

    Science.gov (United States)

    Liu, Mengjia; Li, Jinghong

    2016-01-27

    The development of efficient and low-cost hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts for renewable-energy conversion techniques is highly desired. A kind of hollow polyhedral cobalt phosphide (CoP hollow polyhedron) is developed as efficient bifunctional electrocatalysts for HER and OER templated by Co-centered metal-organic frameworks. The as-prepared CoP hollow polyhedron, which have large specific surface area and high porosity providing rich catalytic active sites, show excellent electrocatalytic performances for both HER and OER in acidic and alkaline media, respectively, with onset overpotentials of 35 and 300 mV, Tafel slopes of 59 and 57 mV dec(-1), and a current density of 10 mA cm(-2) at overpotentials of 159 and 400 mV for HER and OER, respectively, which are remarkably superior to those of particulate CoP (CoP particles) and comparable to those of commercial noble-metal catalysts. In addition, the CoP hollow polyhedron also show good durability after long-term operations. PMID:26711014

  1. Catalytic characterization of bi-functional catalysts derived from Pd–Mg–Al layered double hydroxides

    Indian Academy of Sciences (India)

    N N Das; S C Srivastava

    2002-08-01

    Hydrotalcite like precursors containing PdII–MgII–AlIII with varying molar ratios, (Pd + Mg)/Al ≈ 3 and Mg/Pd ≈ 750 to 35, were prepared by coprecipitation of metal nitrates at constant pH. Characterization of samples as synthesized and their calcined products by elemental analyses, powder XRD, TG–DTA, FT–IR spectroscopy, TPR and N2 physisorption indicated a well crystalline hydrotalcite like structure with incorporation of Pd2+ in the brucite layers. Thermal decomposition of hydrotalcite precursors at intermediate temperatures led to amorphous mixed oxides, Pd/MgAl(O), which on reduction yielded bi-functional catalyst, Pd°/MgAl(O). The resultant catalysts with acid, base and hydrogenating sites, were highly active and selective for one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen. The results showed an optimal balance between acid-base and metallic sites were required to increase the selectivity of MIBK and stability of the catalysts.

  2. The determination of the rate of conjugation immunoglobuline with bifunctional chelator

    Science.gov (United States)

    Málek, Z.; Miler, V.; Budský, F.

    2006-01-01

    The work was performed under the GACR project: "Technology of preparation of radionuclides and their labelled compounds for nuclear medicine and pharmacy with the use of the reactor LVR-15" reg. no. 104/03/0499. Imaging of cell’s antigens with the use of labelled immunoglobulines allows imaging of specific receptors on cell membrane and specific tumours. It is necessary to carry out the labelling of the immunoglobulines with radionuclides of suitable physical properties, which form cations (e.g., 111In, 90Y, 177Lu) that form very strong chelates of sufficiently high stability constant preventing the dissociation of complexes or the radionuclide under “in-vivo” conditions. The immunoglobuline must be conjugated with the bifunctional chelator (BCH), which contains both chelating unit and reactive group for binding to the immunoglobuline. In our laboratory we have conjugated human IgG and monoclonal antibody CD20 with diethylenetriamine pentaacetic acid dianhydride (cDTPAA). Radionuclides 90Y and 177Lu prepared on the LVR-15 reactor in NRI Rez were used for labelling. After conjugation and labelling the yields in relation to the amount of isotopic carrier have been determined.

  3. Bifunctional redox flow battery-1 V(III)/V(II)-glyoxal(O2) system

    International Nuclear Information System (INIS)

    Bifunctional redox flow batteries (BRFB) possess functions of both electricity storage and electrochemical preparation, having the potential for increasing the electrical energy utilization. A V(III)/V(II)-glyoxal(O2) system has been developed. Separators of the BRFB play a key role in BRFB performance. A Nafion solution was sprayed on a gas diffusion layer (GDL) at the Nafion loading of 2 mg cm-2, and the GDL was then hot-pressed onto a Nafion115 cation exchange membrane, obtaining a modified separator. This separator not only prevents the crossover of vanadium but also has favorable conductivity, obtaining optimal charge and organic electro-synthesis performance of the BRFB. The effects of the concentrations of glyoxal and HCl on the performance of BRFB were also investigated. It is shown that the optimal concentration of glyoxal and HCl should be 1.2 and 3 M, respectively. As a result, the current efficiency of organic electro-synthesis is further increased. An acceptable discharge performance is achieved for a period exceeding 20 h at the current density of 20 mA cm-2. The average discharge voltage of 0.73 V and the coulombic efficiency of 66% are obtained. It is demonstrated that the principle of the BRFB is feasible. However, further experiments are needed to improve the performance

  4. Hypoxia targeted bifunctional suicide gene expression enhances radiotherapy in vitro and in vivo

    International Nuclear Information System (INIS)

    Purpose: To investigate whether hypoxia targeted bifunctional suicide gene expression-cytosine deaminase (CD) and uracil phosphoribosyltransferase (UPRT) with 5-FC treatments can enhance radiotherapy. Materials and methods: Stable transfectants of R3327-AT cells were established which express a triple-fusion-gene: CD, UPRT and monomoric DsRed (mDsRed) controlled by a hypoxia inducible promoter. Hypoxia-induced expression/function of CDUPRTmDsRed was verified by western blot, flow cytometry, fluorescent microscopy, and cytotoxicity assay of 5-FU and 5-FC. Tumor-bearing mice were treated with 5-FC and local radiation. Tumor volume was monitored and compared with those treated with 5-FC or radiation alone. In addition, the CDUPRTmDsRed distribution in hypoxic regions of tumor sections was visualized with fluorescent microscopy. Results: Hypoxic induction of CDUPRTmDsRed protein correlated with increased sensitivity to 5-FC and 5-FU. Significant radiosensitization effects were detected after 5-FC treatments under hypoxic conditions. In the tumor xenografts, the distribution of CDUPRTmDsRed expression visualized with fluorescence microscopy was co-localized with the hypoxia marker pimonidazole positive staining cells. Furthermore, administration of 5-FC to mice in combination with local irradiation resulted in significant tumor regression, as in comparison with 5-FC or radiation treatments alone. Conclusions: Our data suggest that the hypoxia-inducible CDUPRT/5-FC gene therapy strategy has the ability to specifically target hypoxic cancer cells and significantly improve the tumor control in combination with radiotherapy.

  5. Bifunctional impedimetric sensors based on azodicarboxamide supported on modified graphene nanosheets.

    Science.gov (United States)

    Azadbakht, Azadeh; Roushani, Mahmoud; Abbasi, Amir Reza; Derikvand, Zohreh; Menati, Saeid

    2016-12-01

    Herein, gold-coated graphene oxide nanosheets hybrid material (GO/AuNPs) with exceptional physical and chemical properties has been utilized as a novel platform for electrode modification. The synthetic method of GO/AuNPs involves anon-covalent functionalization of exfoliated GO with AuNPs based on the reduction of the Au(III) complex by sodium citrate. The prepared GO/AuNPs hybrid exhibits the dispersion of high density AuNPs which were densely decorated on the large surface area of GO. The GO/AuNPs modified glassy carbon (GC) electrode was employed as a sensing platform to immobilize azodicarboxamide (ACA). The morphology, structure and electrochemical performance of the sensor were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that the modified electrode has a notable bifunctional catalytic activity. Electrocatalytic oxidations of cysteine and electrocatalytic reduction of iodate at the surface of modified electrode were investigated with different technique. PMID:27612707

  6. Intermolecular interactions in cyclic complexes with hydrogen bond of bifunctional N-containing compounds in solution

    International Nuclear Information System (INIS)

    The structure of molecular and ionic hydrogen-bonded complexes formed by bifunctional N-containing molecules, which can act as proton donor and proton acceptor simultaneously, and the nature of molecular interactions in these complexes were studied in solution. The spectroscopic, steric and thermodynamic characteristics of self-associates of 3,5-dimethylpyrazole, diphenylformamidine, diphenylguanidine and diphenyltriazene and complexes of these compounds with carboxylic acids were obtained. The quantum chemical calculations of the structure of complexes and the vibrational frequencies in IR spectra were carried out in the harmonic approximation and with the anharmonic effects taken into account. It was shown that under the interaction with weak carboxylic acids (HCOOH, CH3COOH, CH2ClCOOH) the complexes have molecular structure with two H-bonds NH...O=C and OH...N, and the interaction with strong acids (CHCl2COOH, CCl3COOH, CF3COOH) results in formation of cyclic hydrogen-bonded ionic pairs with proton transfer from hydroxyl group to the N atom of the azo-compound. (authors)

  7. Preparation of magnetic and fluorescent bifunctional chitosan nanoparticles for optical determination of copper ion

    International Nuclear Information System (INIS)

    We describe a simple method for the synthesis of highly magnetic and fluorescent bifunctional chitosan nanoparticles (MF-CSNPs). Water-soluble and magnetic Fe3O4-chitosan nanoparticles and CdSe quantum dots capped with thioglycolic acid were incorporated into a chitosan matrix via electrostatic interaction. The optical, magnetic, crystallographic and morphological properties of the new nanoparticles were studied by UV-visible, fluorescence, X-ray diffraction and transmission electron microscopy. In addition, MF-CSNPs are found to be a useful probe for the determination of copper ion which acts as a quencher of fluorescence. The relative fluorescence intensity of MF-CSNPs is linearly related to the concentration of copper ion in the 0.125 to 25 ng.mL-1 concentration range. The MF-CSNPs also are found to adsorb copper ion which therefore can be separated and enriched by manipulating them with an external magnetic field. Before enrichment, the limit of detection (LOD) for copper ion is 120 pg.mL-1, but after enrichment, the LOD is 46 pg.mL-1. (author)

  8. Cu/Ag-based bifunctional nanoparticles obtained by one-pot laser-assisted galvanic replacement

    International Nuclear Information System (INIS)

    We have prepared, for the first time, stable and uncapped Ag/Cu-based bifunctional nanoparticles (NPs) (BFNPs) in water, by combining ps laser ablation in liquid environment and galvanic replacement. The particles were obtained in a single step by 1,064 nm irradiation of a Cu target in water solutions of AgNO3 or AgNO2. Under proper salt concentration and irradiation conditions, the laser beam activates formation of deep orange colloids, which are positively charged and stable for weeks. High resolution transmission electron microscopy (HRTEM) analysis showed a predominance of composite crystalline nanostructures with size in the 1–15 nm range and consisting of fcc Ag and fcc Cu (or its oxides). While CuO tenorite crystalline phase was detected by HRTEM, X-ray photoelectron spectroscopy analysis permitted to observe also the Cu(I) oxidation state of Cu, being the Cu(I)/Cu(II) ratio different in the samples obtained in AgNO3 or AgNO2 baths. Functionalization with organic ligands and subsequent Raman tests demonstrated the SERS activity of the BFNPs and the existence of different complexing surface sites.

  9. NAD(H recycling activity of an engineered bifunctional enzyme galactose dehydrogenase/lactate dehydrogenase

    Directory of Open Access Journals (Sweden)

    2006-03-01

    Full Text Available A chimeric bifunctional enzyme composing of galactose dehydrogenase (galDH; from Pseudomonas fluorescens and lactate dehydrogenase (LDH; from Bacillus stearothermophilus was successfully constructed. The chimeric galDH/LDH possessed dual characteristics of both galactose dehydrogenase and lactate dehydrogenase activities while exhibiting hexameric rearrangement with a molecular weight of approximately 400 kDa. In vitro observations showed that the chimeric enzyme was able to recycle NAD with a continuous production of lactate without any externally added NADH. Two fold higher recycling rate (0.3 mM/h than that of the native enzyme was observed at pH values above 8.5. Proximity effects became especially pronounced during the recycling assay when diffusion hindrance was induced by polyethylene glycol. All these findings open up a high feasibility to apply the NAD(H recycling system for metabolic engineering purposes e.g. as a model to gain a better understanding on the molecular proximity process and as the routes for synthesizing of numerous high-value-added compounds.

  10. Structure and Function of Fusicoccadiene Synthase, a Hexameric Bifunctional Diterpene Synthase.

    Science.gov (United States)

    Chen, Mengbin; Chou, Wayne K W; Toyomasu, Tomonobu; Cane, David E; Christianson, David W

    2016-04-15

    Fusicoccin A is a diterpene glucoside phytotoxin generated by the fungal pathogen Phomopsis amygdali that causes the plant disease constriction canker, first discovered in New Jersey peach orchards in the 1930s. Fusicoccin A is also an emerging new lead in cancer chemotherapy. The hydrocarbon precursor of fusicoccin A is the tricyclic diterpene fusicoccadiene, which is generated by a bifunctional terpenoid synthase. Here, we report X-ray crystal structures of the individual catalytic domains of fusicoccadiene synthase: the C-terminal domain is a chain elongation enzyme that generates geranylgeranyl diphosphate, and the N-terminal domain catalyzes the cyclization of geranylgeranyl diphosphate to form fusicoccadiene. Crystal structures of each domain complexed with bisphosphonate substrate analogues suggest that three metal ions and three positively charged amino acid side chains trigger substrate ionization in each active site. While in vitro incubations reveal that the cyclase domain can utilize farnesyl diphosphate and geranyl diphosphate as surrogate substrates, these shorter isoprenoid diphosphates are mainly converted into acyclic alcohol or hydrocarbon products. Gel filtration chromatography and analytical ultracentrifugation experiments indicate that full-length fusicoccadiene synthase adopts hexameric quaternary structure, and small-angle X-ray scattering data yield a well-defined molecular envelope illustrating a plausible model for hexamer assembly. PMID:26734760

  11. Exact functional derivative of the nonadditive kinetic-energy bifunctional in the long-distance limit

    Science.gov (United States)

    Jacob, Christoph R.; Beyhan, S. Maya; Visscher, Lucas

    2007-06-01

    We have investigated the functional derivative of the nonadditive kinetic-energy bifunctional, which appears in the embedding potential that is used in the frozen-density embedding formalism, in the limit that the separation of the subsystems is large. We have derived an exact expression for this kinetic-energy component of the embedding potential and have applied this expression to deduce its exact form in this limit. Comparing to the approximations currently in use, we find that while these approximations are correct at the nonfrozen subsystem, they fail completely at the frozen subsystem. Using test calculations on two model systems, a H2O⋯Li+ complex and a cluster of aminocoumarin C151 surrounded by 30 water molecules, we show that this failure leads to a wrong description of unoccupied orbitals, which can lead to convergence problems caused by too low-lying unoccupied orbitals and which can further have serious consequences for the calculation of response properties. Based on our results, a simple correction is proposed, and we show that this correction is able to fix the observed problems for the model systems studied.

  12. Bifunctional polyacrylonitrile fiber-mediated conversion of sucrose to 5-hydroxymethylfurfural in mixed-aqueous systems.

    Science.gov (United States)

    Shi, Xian-Lei; Zhang, Min; Lin, Huikun; Tao, Minli; Li, Yongdan; Zhang, Wenqin

    2015-03-01

    A highly efficient catalytic system composed of a bifunctional polyacrylonitrile fiber (PANF-PA[BnBr]) and a metal chloride was employed to produce 5-hydroxymethylfurfural (HMF) from sucrose in mixed-aqueous systems. The promoter of PANF-PA[BnBr] incorporates protonic acid groups that promote the hydrolysis of the glycosidic bond to convert sucrose into glucose and fructose, and then catalyzes fructose dehydration to HMF, while the ammonium moiety may promote synergetically with the metal chloride the isomerization of glucose to fructose and transfer HMF from the aqueous to the organic phase. The detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber promoter during the modification and utilization processes. Excellent results in terms of high yield (72.8%) of HMF, superior recyclability (6 cycles) of the process, and effective scale-up and simple separation procedures of the catalytic system were obtained. Moreover, the prominent features (high strength, good flexibility, etc.) of the fibers are very attractive for fix-bed reactor. PMID:25573698

  13. Impedimetric and amperometric bifunctional glucose biosensor based on hybrid organic-inorganic thin films.

    Science.gov (United States)

    Wang, Huihui; Ohnuki, Hitoshi; Endo, Hideaki; Izumi, Mitsuru

    2015-02-01

    A novel glucose biosensor with an immobilized mediator was studied using electrochemical impedance spectroscopy (EIS) and amperometry measurements. The biosensor has a characteristic ultrathin form and is composed of a self-assembled monolayer anchoring glucose oxidase (GOx) covered with Langmuir-Blodgett (LB) films of Prussian blue (PB). The immobilized PB in the LB films acts as a mediator and enables the biosensor to work under a low potential (0.0V vs. Ag/AgCl). In the EIS measurements, a dramatic decrease in charge transfer resistance (Rct) was observed with sequential addition of glucose, which can be attributed to enzymatic activity. The linearity of the biosensor response was observed by the variation of the sensor response (1/Rct) as a function of glucose concentration in the range 0 to 25mM. The sensor also showed linear amperometric response below 130mM glucose. The organic-inorganic system of GOx and PB nanoclusters demonstrated bifunctional sensing action, both amperometry and EIS modes, as well as long sensing stability for 4 days. PMID:25014167

  14. Bifunctional Role of the Treponema pallidum Extracellular Matrix Binding Adhesin Tp0751 ▿

    Science.gov (United States)

    Houston, Simon; Hof, Rebecca; Francescutti, Teresa; Hawkes, Aaron; Boulanger, Martin J.; Cameron, Caroline E.

    2011-01-01

    Treponema pallidum, the causative agent of syphilis, is a highly invasive pathogenic spirochete capable of attaching to host cells, invading the tissue barrier, and undergoing rapid widespread dissemination via the circulatory system. The T. pallidum adhesin Tp0751 was previously shown to bind laminin, the most abundant component of the basement membrane, suggesting a role for this adhesin in host tissue colonization and bacterial dissemination. We hypothesized that similar to that of other invasive pathogens, the interaction of T. pallidum with host coagulation proteins, such as fibrinogen, may also be crucial for dissemination via the circulatory system. To test this prediction, we used enzyme-linked immunosorbent assay (ELISA) methodology to demonstrate specific binding of soluble recombinant Tp0751 to human fibrinogen. Click-chemistry-based palmitoylation profiling of heterologously expressed Tp0751 confirmed the presence of a lipid attachment site within this adhesin. Analysis of the Tp0751 primary sequence revealed the presence of a C-terminal putative HEXXH metalloprotease motif, and in vitro degradation assays confirmed that recombinant Tp0751 purified from both insect and Escherichia coli expression systems degrades human fibrinogen and laminin. The proteolytic activity of Tp0751 was abolished by the presence of the metalloprotease inhibitor 1,10-phenanthroline. Further, inductively coupled plasma-mass spectrometry showed that Tp0751 binds zinc and calcium. Collectively, these results indicate that Tp0751 is a zinc-dependent, membrane-associated protease that exhibits metalloprotease-like characteristics. However, site-directed mutagenesis of the HEXXH motif to HQXXH did not abolish the proteolytic activity of Tp0751, indicating that further mutagenesis studies are required to elucidate the critical active site residues associated with this protein. This study represents the first published description of a T. pallidum protease capable of degrading host

  15. Sensitivity to DNA-damaging agents and mutation induction by UV light in UV-sensitive CHO cells

    International Nuclear Information System (INIS)

    Three UV-sensitive (UVs) mutants isolated from a CHO cell line were analyzed for survival after exposure to H2O2, EMS, MMC, CCNU, X-rays and for mutation induction after UV-irradiation. The UVs mutants showed normal sensitivities to EMS and H2O2, whereas they were hypersensitive to the bifunctional alkylating agents MMC and CCNU and to hypoxic X-irradiation. Compared to parental cells, one of the UV-sensitive clones showed approximately 3- and 7-fold enhancement in the mutagenic response per unit UV dose for 6-thioguanine and ouabain resistance, respectively. (Auth.)

  16. 3D-modelling of bifunctional core-shell catalysts for the production of fuels from biomass-based synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Wenjin; Lee, Seung Cheol; Li, Hui; Pfeifer, Peter; Dittmeyer, Roland [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. for Micro Process Engineering (IMVT)

    2013-09-01

    Until now, the main route for the production of DME from synthesis gas in industry is methanol synthesis on a metallic catalyst and subsequent dehydration of methanol on an acid catalyst (two-step process). A single-step process using bifunctional catalysts to perform the two steps simultaneously would be preferred e.g. due to thermodynamic considerations; but this is impeded by the higher volumetric heat release which may cause deactivation of the methanol synthesis catalyst function. Thus we propose to conduct the reaction in a microchannel reactor. However, in order to increase the productivity of the microchannel reactor and to lower the investment costs, we aim at a high selectivity and activity of the catalyst. The continuously removal of methanol by dehydration on an acidic ZSM-5 catalyst as shell improves the thermodynamic conditions of methanol synthesis in the CuO/ZnO/Al{sub 2}O{sub 3} core; thus, the synthesis gas conversion can be higher than that determined by the thermodynamics of pure methanol synthesis. The molecular sieving in the zeolite layer can further lead to higher selectivity of DME at milder reaction conditions. However, mass transport limitation of the synthesis gas to the catalyst core should not hinder the reaction, and therefore a more detailed investigation is required. In order to computer-aided optimize the catalyst structure and the operating conditions for core-shell catalysts, a simulation model should be developed to study the coupled reaction and transport processes in core-shell catalysts. In this simulation model the complicated interaction of diffusion and reaction in the zeolite layer (shell) must be detailed by a network model to describe its structure and the mechanisms effectively. In addition, suitable diffusion and kinetic models are required to describe the mass transport and reactions in the layer. Suitable networks, diffusion and kinetic models are discussed for 3D simulations in this contribution. (orig.)

  17. Acceptorless Dehydrogenative Coupling of o-Aminobenzamides with the Activation of Methanol as a C1 Source for the Construction of Quinazolinones.

    Science.gov (United States)

    Li, Feng; Lu, Lei; Liu, Pengcheng

    2016-06-01

    A strategy for the synthesis of quinazolinones via acceptorless coupling of o-aminobenzamides with methanol has been accomplished in the presence of the metal-ligand bifunctional catalyst [Cp*Ir(2,2'-bpyO)(H2O)]. Notably, this research exhibited the potential of transition-metal-catalyzed activation of methanol as a C1 source for the construction of heterocycles. PMID:27210593

  18. Pd-grafted open metal site copper-benzene-1,4-dicarboxylate metal organic frameworks (Cu-BDC MOF's) as promising interfacial catalysts for sustainable Suzuki coupling.

    Science.gov (United States)

    Rostamnia, Sadegh; Alamgholiloo, Hassan; Liu, Xiao

    2016-05-01

    In this work, open metal site metal-organic framework of Cu-BDC was selected as a support for the multi-step grafting of palladium. The palladium ions was coordinated onto the Schiff base-decorated Cu-BDC pore cage, that this bifunctional Pd@Cu-BDC/Py-SI catalyst was successfully applied for Suzuki cross-coupling reaction. Recyclability test for the Pd@Cu-BDC/Py-SI catalyst showed a successful reusability for 7 runs. PMID:26897567

  19. Asymmetrically coupled directed percolation systems

    OpenAIRE

    Noh, Jae Dong; Park, Hyunggyu

    2005-01-01

    We introduce a dynamical model of coupled directed percolation systems with two particle species. The two species $A$ and $B$ are coupled asymmetrically in that $A$ particles branch $B$ particles whereas $B$ particles prey on $A$ particles. This model may describe epidemic spreading controlled by reactive immunization agents. We study nonequilibrium phase transitions with focused attention to the multicritical point where both species undergo the absorbing phase transition simultaneously. In ...

  20. Acid/base bifunctional carbonaceous nanomaterial with large surface area: Preparation, characterization, and adsorption properties for cationic and anionic compounds

    International Nuclear Information System (INIS)

    Nanostructured carbonaceous materials are extremely important in the nano field, yet developing simple, mild, and “green” methods that can make such materials possess large surface area and rich functional groups on their surfaces still remains a considerable challenge. Herein, a one-pot and environment-friendly method, i.e., thermal treatment (180 °C; 18 h) of water mixed with glucose and chitosan (CTS), has been proposed. The resultant carbonaceous nanomaterials were characterized by field emitting scanning electron microscope, N2 adsorption/desorption, Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, and zeta-potential analysis. It was found that, in contrast to the conventional hydrothermally carbonized product from pure glucose, with low surface area (9.3 m2 g−1) and pore volume (0.016 cm3 g−1), the CTS-added carbonaceous products showed satisfactory textural parameters (surface area and pore volume up to 254 m2 g−1 and 0.701 cm3 g−1, respectively). Moreover, it was also interestingly found that these CTS-added carbonaceous products possessed both acidic (–COOH) and basic (–NH2) groups on their surfaces. Taking the advantages of large surface area and –COOH/–NH2 bifunctional surface, the carbonaceous nanomaterials exhibited excellent performance for adsorptions of cationic compound (i.e., methylene blue) at pH 10 and anionic compound (i.e., acid red 18) at pH 2, respectively. This work not only provides a simple and green route to prepare acid/base bifunctional carbonaceous nanomaterials with large surface area but also well demonstrates their potential for application in adsorption. - Highlights: • A simple and green method was proposed to prepare carbon nanomaterials. • The carbon product showed acid/base bifunctional surface with large surface area. • The carbon material could efficiently adsorb both cationic and anionic compounds

  1. Preparation of carbon gold plate being highly filled with fly ash and investigation of its property affected by silane coupling agent%高填充粉煤灰碳金板材的制备及硅烷偶联剂对其性能的影响

    Institute of Scientific and Technical Information of China (English)

    张琦; 李巧玲; 费少雷; 闫超群

    2016-01-01

    The carbon gold plate highly filled with fly ash was prepared by hot pressing,and its mechanical property was explored by adding different amount of silane coupling agent. The fracture appearance of the obtained plates was observed by SEM. The surface element distribution of the samples was analyzed through EDS. The results indicated that adding proper amount of silane coupling agent (KH550) can improve the mechanical property of the carbon gold plate. When fly ash was 400phr and the content of silane coupling agent (KH550) was 2wt% of the fly ash,the mechanical property of the carbon goldplate reached theoptimal state:the tensile strength,the bending strength and the impact strength were 31.59MPa 58.33MPa and 2.07kJ/m2,respectively,which all met the standards for common architectural decoration materials. The mass fraction of fly ash reached as high as 73 wt%.%采用热压法制备了高填充粉煤灰碳金板材,研究了硅烷偶联剂对碳金板材力学性能的影响。采用扫描电镜对其断面形貌进行检测及能谱分析,结果表明:适当地添加硅烷偶联剂可以提高碳金板材的力学性能。当粉煤灰为400phr、硅烷偶联剂 KH550的添加量为粉煤灰质量的2%时,碳金板材的力学性能达到最佳;拉伸强度31.59MPa,弯曲强度58.33MPa,冲击强度2.07kJ/m2,达到了通用建筑装饰材料的使用指标;粉煤灰填充量高达73%。

  2. Facile preparation of Ag-Cu bifunctional electrocatalysts for zinc-air batteries

    International Nuclear Information System (INIS)

    Highlights: • Ag-Cu dendrites are observed for the first time to exhibit high catalytic activity for oxygen reduction reaction. • Ag-Cu dendrites are directly synthesized through galvanic displacement on the current collector layer made of Ni foams. • A bifunctional air cathode is fabricated using Ag-Cu dendrites as a carbon-free, binder-free catalyst layer. • Both the primary and rechargeable zinc–air batteries fabricated by Ag-Cu catalysts exhibit excellent performance. - ABSTRACT: An inexpensive, facile galvanic displacement reaction for the direct growth of silver–copper (Ag-Cu) catalysts on nickel foams is developed for the first time. The resulting Ag-Cu catalysts exhibit dendritic morphologies. Ag and Cu atoms are in their metallic state while the presence of CuO and Cu2O are limited on the surface of catalyst. The catalysts demonstrate high catalytic activity for oxygen reduction reaction (ORR) in alkaline solution, as evaluated by both linear scanning voltammetry and rotating disk electrode polarization measurements. The ORR catalysed by Ag-Cu catalyst in alkaline solution proceeds through a four-electron pathway. An air cathode is fabricated using Ag-Cu catalyst as a carbon-free, binder-free catalyst layer. Using this Ag-Cu catalyst based air cathode, both the primary and rechargeable zinc-air batteries show excellent battery performance. The specific capacity of the primary zinc-air battery is 572 mAh g−1. Especially, the rechargeable zinc-air battery shows high round-trip efficiency, appealing stability at a long charge-discharge cycle period

  3. Modification of bifunctional epoxy resin using CO{sub 2} fixation process and nanoclay

    Energy Technology Data Exchange (ETDEWEB)

    Khoshkish, Morteza; Bouhendi, Hosein, E-mail: H.boohendi@ippi.ac.ir; Vafayan, Mehdi

    2014-10-15

    A bifunctional epoxy resin was modified by using a CO{sub 2} fixation solution process in the presence of tetra n-butyl ammonium bromide (TBAB) as catalyst and the modified treated resin was treated by cloisite 30B as nano additive. The Unmodified epoxy resin (UME), CO{sub 2} fixated modified epoxy resin (CFME), and CFME/clay nano composite (CFMEN), were cured by diethylenetriamine (DETA). A cycloaliphatic compound as a reactive diluent was used to control the viscosity of high viscose CFME. The exfoliation of organoclay in UME and CFME was investigated by X-ray diffraction and activation energy was computed using the advanced integral isoconversional method. The activation energy dependency demonstrated that the mechanism of UME curing did not change in the presence of nanoclay. In contrast, the CO{sub 2} fixation results showed a significant change in the activation energy dependency. The Thermal stability parameters include the initial degradation temperature (IDT), the temperature at the maximum rate of weight loss (T{sub max}), and the decomposition activation energy (E{sub d}) were determined by thermal gravimetry analysis. Dynamic mechanical thermal analysis measurements showed that the presence of organoclay in CFME increases the T{sub g} of nano composite in contrast to UME. The fracture roughness of UME, CFME and CFNE were determined by scanning electron microscope. The exfoliated UME/1%clay nanocomposite was confirmed by TEM image. - Highlights: • A new epoxy resin was synthesized using CO{sub 2} fixation reaction. • The synthesized epoxy resin was modified by an organo nano-clay. • CO{sub 2} fixation noticeably changed the curing mechanism. • CO{sub 2} fixation reaction consumes CO{sub 2} which is a harmful greenhouse gas.

  4. Cloning and Functional Analysis of the Bifunctional Agglutinin/Trypsin Inhibitor from Helianthus tuberosus L.

    Institute of Scientific and Technical Information of China (English)

    Tuanjie Chang; Hongli Zhai; Songbiao Chen; Guisheng Song; Honglin Xu; Xiaoli Wei; Zhen Zhu

    2006-01-01

    In order to find new insect resistance genes, four homologous cDNAs, hta-a, hta-b, hta-c and hta-d with lengths of 775, 718, 784 and 752 bp, respectively (GenBank accession numbers AF477031-AF477034), were isolated from a tuber cDNA expression library of Helianthus tuberosus L. Sequence analysis revealed that all four cDNAs contain an open reading frame of 444 bp, coding a polypeptide of 147 amino acid residues, and that the sequences of the cDNAs are very similar to those of the mannose-binding agglutinin genes of the jacalin-related family. In hemagglutination reactions and hapten inhibition assays, affinity-purified HTA (Helianthus tuberosus agglutinin) from induced Escherichia coli BL21(DE3) expressing GST-HTA shows hemagglutination ability and a higher carbohydrate-binding ability for mannose than other tested sugars.Trypsin inhibitory activity was detected in the crude extracts of induced E. coli BL21(DE3)expressing HTA,and was further verified by trypsin inhibitory activity staining on native polyacrylamide gel. The mechanism of interaction between HTA and trypsin was studied by molecular modeling. We found that plenty of hydrogen bonds and electrostatic interactions can be formed between the supposed binding sites of HTA-b and the active site of trypsin, and that a stable HTA/trypsin complex can be formed. The results above imply that HTA might be a bifunctional protein with carbohydrate-binding activity and trypsin inhibitory activity. Moreover,Northern blotting analysis demonstrated that hta is predominantly expressed in tubers of H. tuberosus, very weakly expressed in stems, but not expressed at all in other tissues. Southern blotting analysis indicated that hta is encoded by a multi-gene family. The insect resistance traits have been described in another paper.

  5. Improvement of L-arginine production by overexpression of a bifunctional ornithine acetyltransferase in Corynebacterium crenatum.

    Science.gov (United States)

    Dou, Wenfang; Xu, Meijuan; Cai, Dongmei; Zhang, Xiaomei; Rao, Zhiming; Xu, Zhenghong

    2011-10-01

    Ornithine acetyltransferase (EC 2.3.1.35; OATase) gene (argJ) from the L-arginine-producing mutant Corynebacterium crenatum SYPA5-5 was cloned, sequenced, and expressed in Escherichia coli BL21 (DE3). Analysis of the argJ sequence revealed that the argJ coded a polypeptide of 388 amino acids with a calculated molecular weight of 39.7 kDa. In this study, the function of the OATase (argJ) of C. crenatum SYPA5-5 has been identified as a conserved ATML sequence for the autolysis of the protein to α- and β-subunits. When the argJ regions corresponding to the α- and β-subunits were cloned and expressed separately in E. coli BL21, OATase activities were abolished. At the same time, a functional study revealed that OATase from C. crenatum SYPA5-5 was a bifunctional enzyme with the functions of acetylglutamate synthase (EC 2.3.1.1, NAGS) and acetylornithine deacetylase (EC 3.5.1.16, AOase) activities. In order to investigate the effects of the overexpression of the argJ gene on L: -arginine production, the argJ gene was inserted into pJCtac to yield the recombinant shuttle plasmid pJCtac-argJ and then transformed into C. crenatum SYPA5-5. The results showed that the engineered strains could not only express more OATase (90.9%) but also increase the production of L: -arginine significantly (16.8%). PMID:21785983

  6. Characterization and kinetic mechanism of mono- and bifunctional ornithine acetyltransferases from thermophilic microorganisms.

    Science.gov (United States)

    Marc, F; Weigel, P; Legrain, C; Almeras, Y; Santrot, M; Glansdorff, N; Sakanyan, V

    2000-08-01

    The argJ gene coding for N2-acetyl-L-ornithine: L-glutamate N-acetyltransferase, the key enzyme involved in the acetyl cycle of L-arginine biosynthesis, has been cloned from thermophilic procaryotes: the archaeon Methanoccocus jannaschii, and the bacteria Thermotoga neapolitana and Bacillus stearothermophilus. Archaeal argJ only complements an Escherichia coli argE mutant (deficient in acetylornithinase, which catalyzes the fifth step in the linear biosynthetic pathway), whereas bacterial genes additionally complement an argA mutant (deficient in N-acetylglutamate synthetase, the first enzyme of the pathway). In keeping with these in vivo data the purified His-tagged ArgJ enzyme of M. jannaschii only catalyzes N2-acetylornithine conversion to ornithine, whereas T. neapolitana and B. stearothermophilus ArgJ also catalyze the conversion of glutamate to N-acetylglutamate using acetylCoA as the acetyl donor. M. jannaschii ArgJ is therefore a monofunctional enzyme, whereas T. neapolitana and B. stearothermophilus encoded ArgJ are bifunctional. Kinetic data demonstrate that in all three thermophilic organisms ArgJ-mediated catalysis follows ping-pong bi-bi kinetic mechanism. Acetylated ArgJ intermediates were detected in semireactions using [14C]acetylCoA or [14C]N2-acetyl-L-glutamate as acetyl donors. In this catalysis L-ornithine acts as an inhibitor; this amino acid therefore appears to be a key regulatory molecule in the acetyl cycle of L-arginine synthesis. Thermophilic ArgJ are synthesized as protein precursors undergoing internal cleavage to generate alpha and beta subunits which appear to assemble to alpha2beta2 heterotetramers in E. coli. The cleavage occurs between alanine and threonine residues within the highly conserved PXM-ATML motif detected in all available ArgJ sequences. PMID:10931207

  7. Bifunctional oligodeoxynucleotide/antagomiR constructs: evaluation of a new tool for microRNA silencing.

    Science.gov (United States)

    Ziegler, Saskia; Eberle, Mariel Esther; Wölfle, Sabine J; Heeg, Klaus; Bekeredjian-Ding, Isabelle

    2013-12-01

    MicroRNAs (miRNAs) are fine-tuners in cellular processes, including those of the immune response. To study their functions and effects in immune cells, it is necessary to achieve specific silencing of individual miRNAs. To date, introduction of antisense microRNAs (antagomiRs) into primary cells is based on electroporation, lipofection, and viral vectors. However, these techniques often compromise viability, proliferative capacity, and differentiation. Furthermore, efficiency varies depending on the cell type and some are not suitable for in vivo approaches. To overcome these limitations we exploited the property of phosphorothioate (PTO)-modified DNA oligodeoxynucleotides (ODN) to enter cells with high efficacy: we developed and evaluated ODN/antagomiR constructs that consist of a PTO-ODN carrier covalently linked to a fully methylated antagomiR RNA sequence. Using these constructs, we achieved transfection efficiency of approximately 99% in leukocytes-in particular, in B lymphocytes that are hard to transfect with other methods. Our data demonstrate that miRNA silencing by the antagomiR portion of the constructs was specific and efficient, which could be further confirmed by an increase in target protein under silencing conditions. The constructs were successfully tested in human B cells, plasmacytoid dendritic cells, monocytes, and monocyte-derived dendritic cells, thus demonstrating their versatility. Moreover, introduction of stimulatory CpG sequences into the ODN portion conveys immune stimulatory quality when intended. Thus, bifunctional ODN/antagomiR constructs represent a highly efficient, versatile, and easy-to-handle tool to manipulate cellular miRNA expression levels and to allow the subsequent investigation of specific miRNA functions. PMID:24236889

  8. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions

    Science.gov (United States)

    Zhang, Jintao; Zhao, Zhenghang; Xia, Zhenhai; Dai, Liming

    2015-05-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out with noble metals (such as Pt) and metal oxides (such as RuO2 and MnO2) as catalysts, respectively. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. Here, we describe a mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area of ˜1,663 m2 g-1 and good electrocatalytic properties for both ORR and OER. This material was fabricated using a scalable, one-step process involving the pyrolysis of a polyaniline aerogel synthesized in the presence of phytic acid. We then tested the suitability of this N,P-doped carbon foam as an air electrode for primary and rechargeable Zn-air batteries. Primary batteries demonstrated an open-circuit potential of 1.48 V, a specific capacity of 735 mAh gZn-1 (corresponding to an energy density of 835 Wh kgZn-1), a peak power density of 55 mW cm-2, and stable operation for 240 h after mechanical recharging. Two-electrode rechargeable batteries could be cycled stably for 180 cycles at 2 mA cm-2. We also examine the activity of our carbon foam for both OER and ORR independently, in a three-electrode configuration, and discuss ways in which the Zn-air battery can be further improved. Finally, our density functional theory calculations reveal that the N,P co-doping and graphene edge effects are essential for the bifunctional electrocatalytic activity of our material.

  9. Crystal structure of two new bifunctional nonsubstrate type thrombin inhibitors complexed with human alpha-thrombin.

    Science.gov (United States)

    Féthière, J.; Tsuda, Y.; Coulombe, R.; Konishi, Y.; Cygler, M.

    1996-01-01

    The crystal structures of two new thrombin inhibitors, P498 and P500, complexed with human alpha-thrombin have been determined at 2.0 A resolution and refined to crystallographic R-factors of 0.170 and 0.169, respectively. These compounds, with picomolar binding constants, belong to a family of potent bifunctional inhibitors that bind thrombin at two remote sites: the active site and the fibrinogen recognition exosite (FRE). The inhibitors incorporate a nonsubstrate type active site binding fragment: Dansyl-Arg-(D)Pipecolic acid (Dns-Arg-(D)Pip), reminiscent of the active-site directed inhibitors MD-805 and MQPA, rendering them resistant to thrombin-induced hydrolysis. The FRE binding fragment of these inhibitors corresponds to the hirudin55-65 sequence. They differ in the chemical nature of the nonpeptidyl linker bridging these two functional activities. In both cases, the active site binding fragment is well defined in the electron density. The DnsH1, ArgH2, and (D)PipH3 groups occupy the S3, S1, and S2 subsites of thrombin, respectively, in a way similar to that observed in the thrombin-MQPA complexes. Binding in the active site of thrombin is characterized by numerous van der Waals contacts and ring-ring system interactions. Unlike in the substrate-like inhibitors, ArgH2 enters the S1 specificity pocket from the P2 position and adopts a bent conformation to make an hydrogen bond to the carboxylate of Asp189. In this noncanonical position, its carbonyl points away from the oxyanion hole, which is now occupied by well-ordered solvent molecules. The linkers fit in the groove extending from the active site to the FRE. The C-terminal fragments of both inhibitors bind in the same way as analogous FRE binding elements in previously described complexes. PMID:8762149

  10. Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts.

    Science.gov (United States)

    Touge, Taichiro; Nara, Hideki; Fujiwhara, Mitsuhiko; Kayaki, Yoshihito; Ikariya, Takao

    2016-08-17

    A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee. PMID:27463264

  11. A Novel Bifunctional Hybrid with Marine Bacterium Alkaline Phosphatase and Far Eastern Holothurian Mannan-Binding Lectin Activities

    OpenAIRE

    Larissa Balabanova; Vasily Golotin; Svetlana Kovalchuk; Alexander Bulgakov; Galina Likhatskaya; Oksana Son; Valery Rasskazov

    2014-01-01

    A fusion between the genes encoding the marine bacterium Cobetia marina alkaline phosphatase (CmAP) and Far Eastern holothurian Apostichopus japonicus mannan-binding C-type lectin (MBL-AJ) was performed. Expression of the fusion gene in E. coli cells resulted in yield of soluble recombinant chimeric protein CmAP/MBL-AJ with the high alkaline phosphatase activity and specificity of the lectin MBL-AJ. The bifunctional hybrid CmAP/MBL-AJ was produced as a dimer with the molecular mass of 200 kDa...

  12. A Novel N-Acetylglutamate Synthase Architecture Revealed by the Crystal Structure of the Bifunctional Enzyme from Maricaulis maris

    OpenAIRE

    Shi, Dashuang; Li, Yongdong; Cabrera-Luque, Juan; Jin, Zhongmin; Yu, Xiaolin; Zhao, Gengxiang; Haskins, Nantaporn; Allewell, Norma M.; Tuchman, Mendel

    2011-01-01

    Novel bifunctional N-acetylglutamate synthase/kinases (NAGS/K) that catalyze the first two steps of arginine biosynthesis and are homologous to vertebrate N-acetylglutamate synthase (NAGS), an essential cofactor-producing enzyme in the urea cycle, were identified in Maricaulis maris and several other bacteria. Arginine is an allosteric inhibitor of NAGS but not NAGK activity. The crystal structure of M. maris NAGS/K (mmNAGS/K) at 2.7 Å resolution indicates that it is a tetramer, in contrast t...

  13. AgentChess : An Agent Chess Approach

    OpenAIRE

    Fransson, Henric

    2003-01-01

    The game of chess has many times been discussed and used for test purpose by science departments of Artificial Intelligence (AI). Although the technique of agent and as well multi-agent systems is quite old, the use of these offspring of AI within chess is limited. This report describes the project performed applying the use of agents to a chess program. To measure the performance of the logic has tests between the developed program main parts been performed. Further tests against a tradition...

  14. Synthesis of (+)-Antroquinonol: An Antihyperglycemic Agent.

    Science.gov (United States)

    Sulake, Rohidas S; Lin, Hsiao-Han; Hsu, Chia-Yu; Weng, Ching-Feng; Chen, Chinpiao

    2015-06-19

    The total synthesis of antroquinonol has been accomplished through Suzuki-Miyaura cross-coupling and Barton-McCombie reaction, and the α,β-unsaturation was achieved through selenylation and oxidation protocols. In vitro and in vivo studies on the glucose-lowering properties of antroquinonol indicate that it is a potential antidiabetic agent. PMID:26039178

  15. Agents in domestic environments

    OpenAIRE

    van Moergestel, Leo; Langerak, Wouter; Meerstra, Glenn; Nieuwenburg, Niels van; Pape, Franc; Telgen, Daniël; Puik, Erik; meyer, john-jules

    2013-01-01

    Athor supplied : "This paper describes an agent-based architecture for domotics. This architecture is based on requirements about expandability and hardware independence. The heart of the system is a multi-agent system. This system is distributed over several platforms to open the possibility to tie the agents directly to the actuators, sensors and devices involved. This way a level of abstraction is created and all intelligence of the system as a whole is related to the agents involved. A pr...

  16. Culturally Aware Agent Communication

    DEFF Research Database (Denmark)

    Rehm, Matthias; Nakano, Yukiko; Koda, Tomoko;

    2012-01-01

    Agent based interaction in the form of Embodied Conversational Agents (ECAs) has matured over the last decade and agents have become more and more sophisticated in terms of their verbal and nonverbal behavior like facial expressions or gestures. Having such “natural” communication channels...

  17. Riot Control Agents

    Science.gov (United States)

    ... a person has been exposed to riot control agents. Long-term health effects of exposure to riot control agents Prolonged ... person is removed from exposure to riot control agents, long-term health effects are unlikely to occur. How you can ...

  18. Reasoning about emotional agents

    NARCIS (Netherlands)

    Meyer, J.-J.

    2008-01-01

    In this paper we discuss the role of emotions in artificial agent design, and the use of logic in reasoning about the emotional or affective states an agent can reside in. We do so by extending the KARO framework for reasoning about rational agents appropriately. In particular we formalize in this f

  19. Agents modeling agents in information economies

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, J.M.; Durfee, E.H. [Univ. of Michigan, Ann Arbor, MI (United States)

    1996-12-31

    Our goal is to design and build agents that act intelligently when placed in an agent-based information economy, where agents buy and sell services (e.g. thesaurus, search, task planning services, etc.). The economy we are working in is the University of Michigan Digital Library (UMDL), a large scale multidisciplinary effort to build an infrastructure for the delivery of library services. In contrast with a typical economy, an information economy deals in goods and services that are often derived from unique sources (authors, analysts, etc.), so that many goods and services are not interchangeable. Also, the cost of replicating and transporting goods is usually negligible, and the quality of goods and services is difficult to measure objectively: even two sources with essentially the same information might appeal to different audiences. Thus, each agent has its own assessment of the quality of goods and services delivered.

  20. A Novel Bifunctional Hybrid with Marine Bacterium Alkaline Phosphatase and Far Eastern Holothurian Mannan-Binding Lectin Activities

    Science.gov (United States)

    Balabanova, Larissa; Golotin, Vasily; Kovalchuk, Svetlana; Bulgakov, Alexander; Likhatskaya, Galina; Son, Oksana; Rasskazov, Valery

    2014-01-01

    A fusion between the genes encoding the marine bacterium Cobetia marina alkaline phosphatase (CmAP) and Far Eastern holothurian Apostichopus japonicus mannan-binding C-type lectin (MBL-AJ) was performed. Expression of the fusion gene in E. coli cells resulted in yield of soluble recombinant chimeric protein CmAP/MBL-AJ with the high alkaline phosphatase activity and specificity of the lectin MBL-AJ. The bifunctional hybrid CmAP/MBL-AJ was produced as a dimer with the molecular mass of 200 kDa. The CmAP/MBL-AJ dimer model showed the two-subunit lectin part that is associated with two molecules of alkaline phosphatase functioning independently from each other. The highly active CmAP label genetically linked to MBL-AJ has advantaged the lectin-binding assay in its sensitivity and time. The double substitution A156N/F159K in the lectin domain of CmAP/MBL-AJ has enhanced its lectin activity by 25±5%. The bifunctional hybrid holothurian's lectin could be promising tool for developing non-invasive methods for biological markers assessment, particularly for improving the MBL-AJ-based method for early detection of a malignant condition in cervical specimens. PMID:25397876

  1. Preparation of IrO2 nanoparticles with SBA-15 template and its supported Pt nanocomposite as bifunctional oxygen catalyst

    Science.gov (United States)

    Kong, Fan-Dong; Liu, Jing; Ling, Ai-Xia; Xu, Zhi-Qiang; Wang, Hui-Yun; Kong, Qing-Sheng

    2015-12-01

    In the present work, we report the syntheses of IrO2 nanoparticles with SBA-15 template (s-IrO2), and s-IrO2 supported Pt nanocomposite (Pt/s-IrO2) as bifunctional oxygen catalyst. Physical characterizations including X-ray diffraction and transmission electron microscopy demonstrate that s-IrO2 catalyst has excellent uniformity and regularity in particle shape and much ordered distribution in geometric space, and Pt/s-IrO2 catalyst shows a uniform Pt dispersion on the surface of the s-IrO2 particles. Electrochemical analyses prove that s-IrO2 catalyst possesses superior OER activity at operating potentials; and that Pt/s-IrO2 catalyst, in comparison to Pt/commercial IrO2, has higher ESA value and ORR catalytic performance with a mechanism of four-electron pathway and a high ORR efficiency. And as a bifunctional oxygen catalyst, Pt/s-IrO2 also exhibits more remarkable OER performance than the commercial one. The s-IrO2 nanoparticles will be a promising active component (for OER), and suitable for Pt support (for ORR).

  2. Efficient bifunctional catalyst lipase/organophosphonic acid-functionalized silica for biodiesel synthesis by esterification of oleic acid with ethanol.

    Science.gov (United States)

    Yin, Ping; Chen, Wen; Liu, Wei; Chen, Hou; Qu, Rongjun; Liu, Xiguang; Tang, Qinghua; Xu, Qiang

    2013-07-01

    An efficient bifunctional catalyst lipase/organophosphonic acid-functionalized silica (SG-T-P-LS) has been successfully developed, and biodiesel production of fatty acid ethyl ester (FAEE) from free fatty acid (FFA) oleic acid with short-chain alcohol ethanol catalyzed by SG-T-P-LS was investigated. The process optimization using response surface methodology (RSM) was performed and the interactions between the operational variables were elucidated, and it was found that the molar ratio of alcohol to acid was the most significant factor. The optimum values for maximum conversion ratio can be obtained by using a Box-Behnken center-united design, and the conversion ratio could reach 89.94 ± 0.42% under the conditions that ethanol/acid molar ratio was 1.05:1 and SG-T-P-LS to FFA weight ratio was 14.9 wt.% at 28.6°C. The research results show that SG-T-P and LS-20 could work cooperatively to promote the esterification reaction, and the bifunctional catalyst SG-T-P-LS is a potential catalyst for biodiesel production. PMID:23688666

  3. Synthesis and Characterization of Bifunctional Organic-Glasses Based on Diphenylhydrazone and Barbituric Acid Derivative for Photorefractive Application

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ki Hong [KIST, Seoul (Korea, Republic of); Lee, Sang Ho; Choi, Chil Sung; Kim, Nak Joong [Hanyang University, Seoul (Korea, Republic of); Choi, Dong Hoon [Kyunghee University, Youngin (Korea, Republic of)

    2003-12-15

    A series of amorphous molecules that possess both photoconductive and electro-optic properties was synthesized in order to investigate photorefractive properties of bifunctional organic-glasses. Diethylaminobenzaldehyde- diphenylhydrazone was covalently attached to 5-(4-diethylamino-benzylidene)-1,3-dimethylpyrimidine- 2,4,6-trione through a flexible alkyl chain (3, 4, 5, 6 and 10 carbons) containing two ether linkages. The longer linkage not only lowered the glass transition temperature (Tg) of the molecules, but also allowed faster orientation of the chromophore. To examine the photorefractive properties, a 50 μm-thick film was prepared from the mixture of a bifunctional molecule, butyl benzyl phthalate, and C{sup 60}. The photoconductivity of this composite was as high as 8.01 x 10{sup -12} S/cm at 60 V/μm, and the maximum diffraction efficiency (ηmax) of 50 μm-thick film was about 5% at 80 V/μm.

  4. A novel bifunctional hybrid with marine bacterium alkaline phosphatase and Far Eastern holothurian mannan-binding lectin activities.

    Directory of Open Access Journals (Sweden)

    Larissa Balabanova

    Full Text Available A fusion between the genes encoding the marine bacterium Cobetia marina alkaline phosphatase (CmAP and Far Eastern holothurian Apostichopus japonicus mannan-binding C-type lectin (MBL-AJ was performed. Expression of the fusion gene in E. coli cells resulted in yield of soluble recombinant chimeric protein CmAP/MBL-AJ with the high alkaline phosphatase activity and specificity of the lectin MBL-AJ. The bifunctional hybrid CmAP/MBL-AJ was produced as a dimer with the molecular mass of 200 kDa. The CmAP/MBL-AJ dimer model showed the two-subunit lectin part that is associated with two molecules of alkaline phosphatase functioning independently from each other. The highly active CmAP label genetically linked to MBL-AJ has advantaged the lectin-binding assay in its sensitivity and time. The double substitution A156N/F159K in the lectin domain of CmAP/MBL-AJ has enhanced its lectin activity by 25 ± 5%. The bifunctional hybrid holothurian's lectin could be promising tool for developing non-invasive methods for biological markers assessment, particularly for improving the MBL-AJ-based method for early detection of a malignant condition in cervical specimens.

  5. Optical coupling

    Energy Technology Data Exchange (ETDEWEB)

    Bock, J J [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Gundersen, J [Department of Physics, University of Miami, Coral Gables, FL 33146 (United States); Lee, A T [Department of Physics, University of California, Berkeley CA 94720 Physics Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (United States); Richards, P L [Department of Physics, University of California, Berkeley CA 94720 (United States); Wollack, E, E-mail: James.Bock@jpl.nasa.go, E-mail: gunder@physics.miami.ed, E-mail: Adrian.Lee@berkeley.ed, E-mail: Richards@cosmology.berkeley.ed, E-mail: Edward.j.wollack@nasa.go [Observational Cosmology Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)

    2009-03-01

    This paper describes contributions to the CMBpol Technology Study Workshop concerning optical coupling structures. These are structures in or near the focal plane which convert the free space wave to a superconducting microstrip on a SI wafer, or to the waveguide input to a HEMT receiver. In addition to an introduction and conclusions by the editor, this paper includes independent contributions by Bock on 'Planar Antenna-Coupled Bolometers for CMB Polarimetry', by Gunderson and Wollack on 'Millimeter-Wave Platlet Feeds', and by Lee on 'Multi-band Dual-Polarization Lens-coupled Planar Antennas for Bolometric CMB polarimetry.'

  6. DIAMOnDS - DIstributed Agents for MObile & Dynamic Services

    CERN Document Server

    Shafi, A; Kiani, Saad; Shehzad, Anjum; Farooq, Umer; Ali, Arshad; Legrand, Iosif C.; Newman, Harvey B.

    2003-01-01

    Distributed Services Architecture with support for mobile agents between services, offer significantly improved communication and computational flexibility. The uses of agents allow execution of complex operations that involve large amounts of data to be processed effectively using distributed resources. The prototype system Distributed Agents for Mobile and Dynamic Services (DIAMOnDS), allows a service to send agents on its behalf, to other services, to perform data manipulation and processing. Agents have been implemented as mobile services that are discovered using the Jini Lookup mechanism and used by other services for task management and communication. Agents provide proxies for interaction with other services as well as specific GUI to monitor and control the agent activity. Thus agents acting on behalf of one service cooperate with other services to carry out a job, providing inter-operation of loosely coupled services in a semi-autonomous way. Remote file system access functionality has been incorpor...

  7. Chemo-mechanical Analysis of Bifunctional Linear DGEBA/Linear Amine Resin Casting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Myung, I.H.; Chung, I.J. [Korea Advanced Institute of Science and Technology, Taejon (Korea); Lee, J.R. [Korea Research Institution of Chemical Technology, Taejon (Korea)

    2000-03-01

    To determine the effect of chain length of linear amine curing agents on the thermal and mechanical properties, standard epoxy resin, diglycidyl ether of bisphenol A(DGEBA) was cured with diethylenetriamine (DETA), triethylenetetraamine (TETA) and tetraethylenepentaamine (TEPA) in a stoichiometrically equivalent ratio. From this work, the effect of linear amine curing agents on the thermal and mechanical properties was significantly influenced by chain length of curing agents. In contrast, the results showed that the DGEBA/DETA system had higher values than the DGEBA/TETA and DGEBA/TEPA system in the density, shrinkage (%), thermal expansion coefficient, tensile modulus, and flexural strength. Whereas the DGEBA/TEPA cure system in the maximum exothermic temperature, conversion (%), and T{sub g}. These findings imply that the differences in the maximum conversion about the chain length of curing agents affect the thermal and mechanical properties. (author). 15 refs., 1 tab., 6 figs.

  8. Electrospinning preparation and properties of magnetic-photoluminescent bifunctional bistrand-aligned composite nanofibers bundles

    International Nuclear Information System (INIS)

    Fe3O4/PVP//Eu(BA)3phen/PVP magnetic-photoluminescent bifunctional bistrand-aligned composite nanofibers bundles based on ferroferric oxide(Fe3O4) nanoparticles and europium complex Eu(BA)3phen (BA = benzoic acid) were fabricated via electrospinning by employing a homemade parallel axial electrospinning setup with the side by side dual spinnerets for the first time. The structures, morphology, and properties of the as-prepared products were investigated in detail by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy (TEM), a fluorescence spectrometer, and a vibrating sample magnetometer. SEM analysis showed the average diameter of the individual-strand fiber of the bistrand-aligned composite nanofibers bundles was 200 ± 25 nm. TEM image demonstrated that Fe3O4 nanoparticles were only dispersed into one strand of the bistrand-aligned composite nanofibers bundles, and the average diameter of Fe3O4 nanoparticles was about 15 nm. Under the excitation of 274 nm ultraviolet light, Fe3O4/PVP//Eu(BA)3phen/PVP bistrand-aligned composite nanofibers bundles exhibited red emissions of predominant peaks at 592 and 616 nm, which were respectively attributed to the 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3+ ions. The fluorescence intensity of the bistrand-aligned composite nanofibers bundles was higher than that of Fe3O4/Eu(BA)3phen/PVP composite nanofibers, and was decreased with the increase of the amounts of Fe3O4 nanoparticles. The saturation magnetizations of the bistrand-aligned composite nanofibers bundles and the Fe3O4/Eu(BA)3phen/PVP composite nanofibers were about equal when the two nanostructures contained the same mass ratios of Fe3O4 nanoparticles, but the saturation magnetizations of the bistrand-aligned composite nanofibers bundles were increased with the increase of the amounts of Fe3O4 nanoparticles. The new type Fe3O4/PVP//Eu(BA)3phen/PVP bistrand-aligned composite nanofibers

  9. Structures of dCTP deaminase from Escherichia coli with bound substrate and product: reaction mechanism and determinants of mono- and bifunctionality for a family of enzymes

    DEFF Research Database (Denmark)

    Johansson, Eva; Fanø, Mathias; Bynck, Julie H;

    2005-01-01

    complex with dUTP and Mg(2+), and the mutant enzyme also with the substrate dCTP and Mg(2+). The enzyme is a third member of the family of the structurally related trimeric dUTPases and the bifunctional dCTP deaminase-dUTPase from Methanocaldococcus jannaschii. However, the C-terminal fold is completely...

  10. Multi-agent autonomous system

    Science.gov (United States)

    Fink, Wolfgang (Inventor); Dohm, James (Inventor); Tarbell, Mark A. (Inventor)

    2010-01-01

    A multi-agent autonomous system for exploration of hazardous or inaccessible locations. The multi-agent autonomous system includes simple surface-based agents or craft controlled by an airborne tracking and command system. The airborne tracking and command system includes an instrument suite used to image an operational area and any craft deployed within the operational area. The image data is used to identify the craft, targets for exploration, and obstacles in the operational area. The tracking and command system determines paths for the surface-based craft using the identified targets and obstacles and commands the craft using simple movement commands to move through the operational area to the targets while avoiding the obstacles. Each craft includes its own instrument suite to collect information about the operational area that is transmitted back to the tracking and command system. The tracking and command system may be further coupled to a satellite system to provide additional image information about the operational area and provide operational and location commands to the tracking and command system.

  11. Preparation and characteristics of Fe{sub 3}O{sub 4}-YVO{sub 4}:Eu{sup 3+} bifunctional magnetic-luminescent nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Peng Hongxia [School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Liu Guixia, E-mail: liuguixia22@yahoo.com.cn [School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Dong Xiangting; Wang Jinxian; Xu Jia; Yu Wensheng [School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China)

    2011-06-16

    Graphical abstract: Highlights: > Bifunctional magnetic-luminescent nanocomposites with Fe{sub 3}O{sub 4} nanoparticles as the core and YVO{sub 4}:Eu{sup 3+} as the shell. > A cubic spinel structrue of Fe{sub 3}O{sub 4} core and a tetragonal phase of YVO{sub 4} shell were obtained. > The nanocomposites displayed a strong red emission and superparamagnetic behavior at room temperature. - Abstract: A facile direct precipitation method has been developed for the synthesis of bifunctional magnetic-luminescent nanocomposites with Fe{sub 3}O{sub 4} nanoparticles as the core and YVO{sub 4}:Eu{sup 3+} as the shell. Transmission electron microscopy (TEM) images revealed that the obtained bifunctional nanocomposites had a core-shell structure and a spherical morphology. The average size was {approx}150 nm, and the thickness of the shell was {approx}15 nm. The X-ray diffraction (XRD) patterns showed that a cubic spinel structure of Fe{sub 3}O{sub 4} core and a tetragonal phase of YVO{sub 4} shell were obtained. Fourier transform infrared (FT-IR) spectra confirmed that the YVO{sub 4}:Eu{sup 3+} had been successfully deposited on the surface of Fe{sub 3}O{sub 4} nanoparticles. Photoluminescence (PL) spectra indicated that the nanocomposites displayed a strong red characteristic emission of Eu{sup 3+}. Magnetic measurements showed that the obtained bifunctional nanocomposites exhibited superparamagnetic behavior at room temperature. Therefore, the bifunctional nanocomposites are expected to develop many potential applications in biomedical fields.

  12. Serial femtosecond crystallography datasets from G protein-coupled receptors.

    Science.gov (United States)

    White, Thomas A; Barty, Anton; Liu, Wei; Ishchenko, Andrii; Zhang, Haitao; Gati, Cornelius; Zatsepin, Nadia A; Basu, Shibom; Oberthür, Dominik; Metz, Markus; Beyerlein, Kenneth R; Yoon, Chun Hong; Yefanov, Oleksandr M; James, Daniel; Wang, Dingjie; Messerschmidt, Marc; Koglin, Jason E; Boutet, Sébastien; Weierstall, Uwe; Cherezov, Vadim

    2016-01-01

    We describe the deposition of four datasets consisting of X-ray diffraction images acquired using serial femtosecond crystallography experiments on microcrystals of human G protein-coupled receptors, grown and delivered in lipidic cubic phase, at the Linac Coherent Light Source. The receptors are: the human serotonin receptor 2B in complex with an agonist ergotamine, the human δ-opioid receptor in complex with a bi-functional peptide ligand DIPP-NH2, the human smoothened receptor in complex with an antagonist cyclopamine, and finally the human angiotensin II type 1 receptor in complex with the selective antagonist ZD7155. All four datasets have been deposited, with minimal processing, in an HDF5-based file format, which can be used directly for crystallographic processing with CrystFEL or other software. We have provided processing scripts and supporting files for recent versions of CrystFEL, which can be used to validate the data. PMID:27479354

  13. Prosthesis coupling

    Science.gov (United States)

    Reswick, J. B.; Mooney, V.; Bright, C. W.; Owens, L. J. (Inventor)

    1979-01-01

    A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump.

  14. Acid/base bifunctional carbonaceous nanomaterial with large surface area: Preparation, characterization, and adsorption properties for cationic and anionic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kai; Ma, Chun–Fang; Ling, Yuan; Li, Meng [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Gao, Qiang, E-mail: gaoqiang@cug.edu.cn [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geo Materials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Luo, Wen–Jun, E-mail: heartnohome@yahoo.com.cn [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China)

    2015-07-15

    Nanostructured carbonaceous materials are extremely important in the nano field, yet developing simple, mild, and “green” methods that can make such materials possess large surface area and rich functional groups on their surfaces still remains a considerable challenge. Herein, a one-pot and environment-friendly method, i.e., thermal treatment (180 °C; 18 h) of water mixed with glucose and chitosan (CTS), has been proposed. The resultant carbonaceous nanomaterials were characterized by field emitting scanning electron microscope, N{sub 2} adsorption/desorption, Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, and zeta-potential analysis. It was found that, in contrast to the conventional hydrothermally carbonized product from pure glucose, with low surface area (9.3 m{sup 2} g{sup −1}) and pore volume (0.016 cm{sup 3} g{sup −1}), the CTS-added carbonaceous products showed satisfactory textural parameters (surface area and pore volume up to 254 m{sup 2} g{sup −1} and 0.701 cm{sup 3} g{sup −1}, respectively). Moreover, it was also interestingly found that these CTS-added carbonaceous products possessed both acidic (–COOH) and basic (–NH{sub 2}) groups on their surfaces. Taking the advantages of large surface area and –COOH/–NH{sub 2} bifunctional surface, the carbonaceous nanomaterials exhibited excellent performance for adsorptions of cationic compound (i.e., methylene blue) at pH 10 and anionic compound (i.e., acid red 18) at pH 2, respectively. This work not only provides a simple and green route to prepare acid/base bifunctional carbonaceous nanomaterials with large surface area but also well demonstrates their potential for application in adsorption. - Highlights: • A simple and green method was proposed to prepare carbon nanomaterials. • The carbon product showed acid/base bifunctional surface with large surface area. • The carbon material could efficiently adsorb both cationic and anionic compounds.

  15. Synthesis and evaluation of a new bifunctional NETA chelate for molecular targeted radiotherapy using90Y or177Lu

    International Nuclear Information System (INIS)

    Introduction: Therapeutic potential of β-emitting cytotoxic radionuclides 90Y and 177Lu has been demonstrated in numerous preclinical and clinical trials. A bifunctional chelate that can effectively complex with the radioisotopes is a critical component for molecular targeted radiotherapy 90Y and 177Lu. A new bifunctional chelate 5p-C-NETA with a relatively long alkyl spacer between the chelating backbone and the functional unit for conjugation to a tumor targeting moiety was synthesized. 5p-C-NETA was conjugated to a model targeting moiety, a cyclic Arg-Gly-Asp-D-Tyr-Lys (RGDyK) peptide binding integrin αvβ3 protein overexpressed on various cancers. 5p-C-NETA was conjugated to c(RGDyK) peptide and evaluated for potential use in molecular targeted radiotherapy of 90Y and 177Lu. Methods: 5p-C-NETA conjugated with c(RGDyK) was evaluated in vitro for radiolabeling, serum stability, binding affinity, and the result of the in vitro studies of 5p-C-NETA-c(RGDyK) was compared to that of 3p-C-NETA-c(RGDyK). 177Lu-5p-C-NETA-c(RGDyK) was further evaluated for in vivo biodistribution using gliobastoma bearing mice. Result: The new chelate rapidly and tightly bound to a cytotoxic radioisotope for cancer therapy, 90Y or 177Lu with excellent radiolabeling efficiency and maximum specific activity under mild condition (> 99%, RT, < 1 min). 90Y- and 177Lu-radiolabeled complexes of the new chelator remained stable in human serum without any loss of the radiolanthanide for 14 days. Introduction of the tumor targeting RGD moiety to the new chelator made little impact on complexation kinetics and stability with 90Y or 177Lu. 177Lu-radiolabeled 5p-C-NETA-c(RGDyK) conjugate was shown to target tumors in mice and produced a favorable in vivo stability profile. Conclusion: The results of in vitro and in vivo evaluation suggest that 5p-C-NETA is an effective bifunctional chelate of 90Y and 177Lu that can be applied for generation of versatile molecular targeted radiopharmaceuticals

  16. Chemical crowd control agents.

    Science.gov (United States)

    Menezes, Ritesh G; Hussain, Syed Ather; Rameez, Mansoor Ali Merchant; Kharoshah, Magdy A; Madadin, Mohammed; Anwar, Naureen; Senthilkumaran, Subramanian

    2016-03-01

    Chemical crowd control agents are also referred to as riot control agents and are mainly used by civil authorities and government agencies to curtail civil disobedience gatherings or processions by large crowds. Common riot control agents used to disperse large numbers of individuals into smaller, less destructive, and more easily controllable numbers include chloroacetophenone, chlorobenzylidenemalononitrile, dibenzoxazepine, diphenylaminearsine, and oleoresin capsicum. In this paper, we discuss the emergency medical care needed by sufferers of acute chemical agent contamination and raise important issues concerning toxicology, safety and health. PMID:26658556

  17. Decontamination Data - Blister Agents

    Data.gov (United States)

    U.S. Environmental Protection Agency — Decontamination efficacy data for blister agents on various building materials using various decontamination solutions This dataset is associated with the following...

  18. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    We study possible motivations for co-entrepenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and postdissolution private and financial outcomes with......, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound investment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no evidence of...

  19. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    We study possible motivations for co-entrepenurial couples to start up a joint firm, us-ing a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... female, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound in-vestment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no...

  20. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    2015-01-01

    We study possible motivations for co-entreprenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... female, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound investment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no...

  1. Synthesis of a bifunctional cytidine derivative and its conjugation to RNA for in vitro selection of a cytidine deaminase ribozyme

    Directory of Open Access Journals (Sweden)

    Nico Rublack

    2014-08-01

    Full Text Available Over the past 20 years, the generation of functional RNAs by in vitro selection has become a standard technique. Apart from aptamers for simple binding of defined ligands, also RNAs for catalysis of chemical reactions have been selected. In the latter case, a key step often is the conjugation of one of the two reactants to the library, requiring suitable strategies for terminal or internal RNA functionalization. With the aim of selecting a ribozyme for deamination of cytidine, we have set up a selection scheme involving the attachment of the cytidine acting as deamination substrate to the 3'-terminus of the RNAs in the library, and library immobilization. Here, we report the synthesis of a bifunctional cytidine derivative suitable for conjugation to RNA and linkage of the conjugated library to a streptavidine-coated surface. Successful conjugation of the cytidine derivative to the 3'-terminus of a model RNA is demonstrated.

  2. Identification and Overexpression of a Bifunctional Aldehyde/Alcohol Dehydrogenase Responsible for Ethanol Production in Thermoanaerobacter mathranii

    DEFF Research Database (Denmark)

    Yao, Shuo; Just Mikkelsen, Marie

    2010-01-01

    ethanol as a fermentation product, while other adh knockout strains showed no significant difference from the wild type. Further analysis revealed that the ΔadhE strain was defective in aldehyde dehydrogenase activity, but still maintained alcohol dehydrogenase activity. This showed that AdhE is the major......Thermoanaerobacter mathranii contains four genes, adhA, adhB, bdhA and adhE, predicted to code for alcohol dehydrogenases involved in ethanol metabolism. These alcohol dehydrogenases were characterized as NADP(H)-dependent primary alcohol dehydrogenase (AdhA), secondary alcohol dehydrogenase (Adh......B), butanol dehydrogenase (BdhA) and NAD(H)-dependent bifunctional aldehyde/alcohol dehydrogenase (AdhE), respectively. Here we observed that AdhE is an important enzyme responsible for ethanol production in T. mathranii based on the constructed adh knockout strains. An adhE knockout strain fails to produce...

  3. The bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provides a tool for molecular and biotechnology applications

    Directory of Open Access Journals (Sweden)

    Tiedtke Arno

    2006-03-01

    Full Text Available Abstract Background Dihydrofolate reductase (DHFR and thymidylate synthase (TS are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme. Results Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first aspect of the presented work relates to destruction of DHFR-TS enzyme function in an alveolate thereby causing an auxotrophy for thymidine. A second aspect is to knock in an expression cassette encoding for a foreign gene with subsequent expression of the target protein. Conclusion This system avoids the use of antibiotics or other drugs and therefore is of high interest for biotechnological applications.

  4. The EpsE flagellar clutch is bifunctional and synergizes with EPS biosynthesis to promote Bacillus subtilis biofilm formation.

    Directory of Open Access Journals (Sweden)

    Sarah B Guttenplan

    Full Text Available Many bacteria inhibit motility concomitant with the synthesis of an extracellular polysaccharide matrix and the formation of biofilm aggregates. In Bacillus subtilis biofilms, motility is inhibited by EpsE, which acts as a clutch on the flagella rotor to inhibit motility, and which is encoded within the 15 gene eps operon required for EPS production. EpsE shows sequence similarity to the glycosyltransferase family of enzymes, and we demonstrate that the conserved active site motif is required for EPS biosynthesis. We also screen for residues specifically required for either clutch or enzymatic activity and demonstrate that the two functions are genetically separable. Finally, we show that, whereas EPS synthesis activity is dominant for biofilm formation, both functions of EpsE synergize to stabilize cell aggregates and relieve selective pressure to abolish motility by genetic mutation. Thus, the transition from motility to biofilm formation may be governed by a single bifunctional enzyme.

  5. Nonlinearity of the Bifunctional of the Nonadditive Kinetic Energy: Numerical Consequences in Orbital-Free Embedding Calculations

    OpenAIRE

    Dulak, Marcin; Wesolowski, Tomasz Adam

    2006-01-01

    The bifunctional of the nonadditive kinetic energy in the reference system of noninteracting electrons ( [ρA, ρB] = Ts[ρA + ρB] − Ts[ρA] − Ts[ρB]) is the key quantity in orbital-free embedding calculations because they hinge on approximations to [ρA,ρB]. Since [ρA,ρB] is not linear in ρA, the associated potential (functional derivative) [ρ,ρB]/δρ|ρ=ρA(r) changes if ρA varies. In this work, for two approximations to [ρA,ρB], which are nonlinear in ρA (gradient-free and gradient-dependent), the...

  6. RNA Secondary Structure Modulates FMRP’s Bi-Functional Role in the MicroRNA Pathway

    Directory of Open Access Journals (Sweden)

    Phillip Kenny

    2016-06-01

    Full Text Available MicroRNAs act by post-transcriptionally regulating the gene expression of 30%–60% of mammalian genomes. MicroRNAs are key regulators in all cellular processes, though the mechanism by which the cell activates or represses microRNA-mediated translational regulation is poorly understood. In this review, we discuss the RNA binding protein Fragile X Mental Retardation Protein (FMRP and its role in microRNA-mediated translational regulation. Historically, FMRP is known to function as a translational suppressor. However, emerging data suggests that FMRP has both an agonistic and antagonistic role in regulating microRNA-mediated translational suppression. This bi-functional role is dependent on FMRP’s interaction with the RNA helicase Moloney leukemia virus 10 (MOV10, which modifies the structural landscape of bound mRNA, therefore facilitating or inhibiting its association with the RNA-Induced Silencing Complex.

  7. N-Terminal Modification with Pseudo-Bifunctional PEG-Hexadecane Markedly Improves the Pharmacological Profile of Human Growth Hormone.

    Science.gov (United States)

    Wu, Ling; Ji, Shaoyang; Hu, Tao

    2015-05-01

    Human growth hormone (hGH) has been used to treat children with short stature, renal failure, and Turner's syndrome. However, clinical application of hGH suffers from its short plasma half-life and low bioavailability. PEGylation and albumin binding are two of the most effective approaches to prolong the plasma half-life of hGH. However, the steric shielding effects of polyethylene glycol (PEG) and albumin can drastically decrease the bioactivity of hGH, which is opposite to the increased pharmacokinetics (PK). In the present study, a long-acting hGH with markedly improved pharmacological profile was rationally designed and prepared by N-terminal modification of hGH with pseudo-bifunctional PEG-hexadecane by using PEG (3.5 kDa or 10 kDa) as the linker. PEGylation and albumin binding with hexadecane can increase the hydrodynamic volume and decrease the immunogenicity of hGH, which thereby markedly increases the PK of hGH. Since N-terminus is far from the bioactive domain of hGH, N-terminal modification of hGH can minimize the steric shielding effects on the bioactive domain of hGH. Hexadecane-bound albumin can be slowly released from hGH during the in vivo circulation, which can slowly restore the bioactivity of hGH. Thus, the high bioactivity of PEG-hexadecane modified hGH (hGH-PEG-HD) was synergistically achieved by N-terminal modification with pseudo-bifunctional PEG-hexadecane and slow-release of albumin. The high pharmacodynamics (PD) of hGH-PEG-HD was due to the synergistic effect of the high bioactivity and the overall increased PK. PMID:25849255

  8. Agent Development Toolkits

    CERN Document Server

    Singh, Aarti; Sharma, A K

    2011-01-01

    Development of agents as well as their wide usage requires good underlying infrastructure. Literature indicates scarcity of agent development tools in initial years of research which limited the exploitation of this beneficial technology. However, today a wide variety of tools are available, for developing robust infrastructure. This technical note provides a deep overview of such tools and contrasts features provided by them.

  9. Radiographic scintiscanning agent

    International Nuclear Information System (INIS)

    A new technetium-based scintiscanning agent has been prepared comprising a water soluble sup(99m)Tc-methanehydroxydiphosphonate in combination with a reducing agent selected from stannous, ferrous, chromous and titanous salts. As an additional stabilizer salts and esters of gentisic or ascorbic acids have been used. (E.G.)

  10. Crystallization and tile separation in the multi-agent systems

    Science.gov (United States)

    Collet, Jacques Henri; Fanchon, Jean

    2015-10-01

    This paper deals with the self-organization of simple mobile agents confined in a two-dimension rectangular area. Each agent interacts with its neighbors inside an interaction disk and moves following various types of force-driven couplings (e.g. repulsion or attraction). The agents do not know their absolute position, do not exchange messages, have no memory, and no learning capabilities. We first study the self-organization appearing in systems made-up with one sole type of agents, initially generated at random in the terrain. By changing the agent-agent repulsive interaction, we observe five different population reorganizations, namely, grouping, diffusion (that is classical), but especially interesting, crystallization (i.e., the agents group together on the vertices a regular hexagonal lattice), alignment along straight lines, and vortex dynamics. Then, we consider reorganization in systems made-up from two to five types of agents, where each pair of agent types has specific interaction parameters. The main result of this work is to show that, by only changing the agent-agent repulsion rules, one can generate hexagonal or rectangular multi-agent crystals or on the contrary, induce complete separation in regular hexagonal tiles.

  11. Asimovian Adaptive Agents

    CERN Document Server

    Gordon, D F

    2011-01-01

    The goal of this research is to develop agents that are adaptive and predictable and timely. At first blush, these three requirements seem contradictory. For example, adaptation risks introducing undesirable side effects, thereby making agents' behavior less predictable. Furthermore, although formal verification can assist in ensuring behavioral predictability, it is known to be time-consuming. Our solution to the challenge of satisfying all three requirements is the following. Agents have finite-state automaton plans, which are adapted online via evolutionary learning (perturbation) operators. To ensure that critical behavioral constraints are always satisfied, agents' plans are first formally verified. They are then reverified after every adaptation. If reverification concludes that constraints are violated, the plans are repaired. The main objective of this paper is to improve the efficiency of reverification after learning, so that agents have a sufficiently rapid response time. We present two solutions: ...

  12. How do agents represent?

    Science.gov (United States)

    Ryan, Alex

    Representation is inherent to the concept of an agent, but its importance in complex systems has not yet been widely recognised. In this paper I introduce Peirce's theory of signs, which facilitates a definition of representation in general. In summary, representation means that for some agent, a model is used to stand in for another entity in a way that shapes the behaviour of the agent with respect to that entity. Representation in general is then related to the theories of representation that have developed within different disciplines. I compare theories of representation from metaphysics, military theory and systems theory. Additional complications arise in explaining the special case of mental representations, which is the focus of cognitive science. I consider the dominant theory of cognition — that the brain is a representational device — as well as the sceptical anti-representational response. Finally, I argue that representation distinguishes agents from non-representational objects: agents are objects capable of representation.

  13. Hyperthermia and chemotherapy agent

    International Nuclear Information System (INIS)

    The use of chemotherapeutic agents for the treatment of cancer dates back to the late 19th century, but the modern era of chemotherapy drugs was ushered in during the 1940's with the development of the polyfunctional alkylating agent. Since then, numerous classes of drugs have evolved and the combined use of antineoplastic agents with other treatment modalities such as radiation or heat, remains a large relatively unexplored area. This approach, combining local hyperthermia with chemotherapy agents affords a measure of targeting and selective toxicity not previously available for drugs. In this paper, the effects of adriamycin, bleomycin and cis-platinum are examined. The adjuvant use of heat may also reverse the resistance of hypoxic cells noted for some chemotherapy agents

  14. Promising bifunctional chelators for copper 64-PET imaging: practical (64)Cu radiolabeling and high in vitro and in vivo complex stability.

    Science.gov (United States)

    Wu, Ningjie; Kang, Chi Soo; Sin, Inseok; Ren, Siyuan; Liu, Dijie; Ruthengael, Varyanna C; Lewis, Michael R; Chong, Hyun-Soon

    2016-04-01

    Positron emission tomography (PET) using copper-64 is a sensitive and non-invasive imaging technique for diagnosis and staging of cancer. A bifunctional chelator that can present rapid radiolabeling kinetics and high complex stability with (64)Cu is a critical component for targeted PET imaging. Bifunctional chelates 3p-C-NE3TA, 3p-C-NOTA, and 3p-C-DE4TA were evaluated for complexation kinetics and stability with (64)Cu in vitro and in vivo. Hexadentate 3p-C-NOTA and heptadentate 3p-C-NE3TA possess a smaller TACN-based macrocyclic backbone, while nonadentate 3p-C-DE4TA is constructed on a larger CYCLEN-based ring. The frequently explored chelates of (64)Cu, octadentate C-DOTA and hexadentate C-NOTA were also comparatively evaluated. Radiolabeling kinetics of bifunctional chelators with (64)Cu was assessed under mild conditions. All bifunctional chelates instantly bound to (64)Cu in excellent radiolabeling efficiency at room temperature. C-DOTA was less efficient in binding (64)Cu than all other chelates. All (64)Cu-radiolabeled bifunctional chelates remained stable in human serum without any loss of (64)Cu for 2 days. When challenged by an excess amount of EDTA, (64)Cu complexes of C-NOTA, 3p-C-NE3TA and 3p-C-NOTA were shown to be more stable than (64)Cu-C-DOTA and (64)Cu-3p-C-DE4TA. (64)Cu complexes of the new chelates 3p-C-NE3TA and 3p-C-NOTA displayed comparable in vitro and in vivo complex stability to (64)Cu-C-NOTA. In vivo biodistribution result indicates that the (64)Cu-radiolabeled complexes of 3p-C-NOTA and 3p-C-NE3TA possess excellent in vivo complex stability, while (64)Cu-3p-C-DE4TA was dissociated as evidenced by high renal and liver retention in mice. The results of in vitro and in vivo studies suggest that the bifunctional chelates 3p-C-NE3TA and 3p-C-NOTA offer excellent chelation chemistry with (64)Cu for potential PET imaging applications. PMID:26666778

  15. Joint chemical agent detector (JCAD): the future of chemical agent detection

    Science.gov (United States)

    Laljer, Charles E.

    2003-08-01

    The Joint Chemical Agent Detector (JCAD) has continued development through 2002. The JCAD has completed Contractor Validation Testing (CVT) that included chemical warfare agent testing, environmental testing, electromagnetic interferent testing, and platform integration validation. The JCAD provides state of the art chemical warfare agent detection capability to military and homeland security operators. Intelligence sources estimate that over twenty countries have active chemical weapons programs. The spread of weapons of mass destruction (and the industrial capability for manufacture of these weapons) to third world nations and terrorist organizations has greatly increased the chemical agent threat to U.S. interests. Coupled with the potential for U.S. involvement in localized conflicts in an operational or support capacity, increases the probability that the military Joint Services may encounter chemical agents anywhere in the world. The JCAD is a small (45 in3), lightweight (2 lb.) chemical agent detector for vehicle interiors, aircraft, individual personnel, shipboard, and fixed site locations. The system provides a common detection component across multi-service platforms. This common detector system will allow the Joint Services to use the same operational and support concept for more efficient utilization of resources. The JCAD detects, identifies, quantifies, and warns of the presence of chemical agents prior to onset of miosis. Upon detection of chemical agents, the detector provides local and remote audible and visual alarms to the operators. Advance warning will provide the vehicle crew and other personnel in the local area with the time necessary to protect themselves from the lethal effects of chemical agents. The JCAD is capable of being upgraded to protect against future chemical agent threats. The JCAD provides the operator with the warning necessary to survive and fight in a chemical warfare agent threat environment.

  16. Power coupling

    OpenAIRE

    D. AlesiniLNF, INFN, Frascati

    2015-01-01

    Power coupling is the subject of a huge amount of literature and material since for each particular RF structure it is necessary to design a coupler that satisfies some requirements, and several approaches are in principle possible. The choice of one coupler with respect to another depends on the particular RF design expertise. Nevertheless some 'design criteria' can be adopted and the scope of this paper is to give an overview of the basic concepts in power coupler design and techniques. We ...

  17. Radio-peptides targeting g-protein coupled receptors in cancer: from bench to bed

    International Nuclear Information System (INIS)

    Full text of publication follows. In the development of targeted imaging and therapy agents the most important challenge and prerequisite is to identify and validate the molecular targets of any disease. The targets should be specific, relevant, easily accessible and highly expressed. In addition they should have no or at least very low expression in normal tissue. Among the many drug targets is the large family of G-protein coupled receptors (GPCRs). It is the most important family of marketed drugs and the basic accomplishments in the field were recognised by the award of the recent Nobel price in chemistry. GPCRs also play a role in cancer. Several of these receptors are massively over-expressed in different human tumors such as neuroendocrine tumors (over-expression of the somatostatin receptor family), prostate and breast tumors (bombesin receptor family), brain tumors (NK1 receptor) etc.. This allows to develop (nuclear, MRI, optical) probes for imaging and potentially targeted therapy (theragnostics). Natural ligands targeting GPCRs are often peptides. They need to be modified for metabolic stability, modified for labeling with radio-metals (conjugation of bifunctional chelators) or radio-halogens (prosthetic groups). Preserved biological integrity after modification and labeling needs to be assured, long retention times in the tumor is important, conferred by internalisation. Radio-metal labeling in particular needs to be reasonably fast and the radio metal complexes have to show high stability with regard to radio-metal release. These prerequisites will be discussed for somatostatin receptor based radio-peptides in particular. For a successful clinical application preclinical imaging and biodistribution in adequate animal models are mandatory. New tracers for positron emission tomography (PET) and single photon emission computed tomography (SPECT) will be presented for neuroendocrine tumors and prostate cancer. In particular radiolabeled antagonists will

  18. 硅烷偶联剂改性纳米SiO2对环氧体系凝胶的影响%Effects of silane coupling agent modified nano - SiO2 on the gel time of epoxy resin system

    Institute of Scientific and Technical Information of China (English)

    郑延辉; 姜俊青; 张延武; 柴文翠

    2011-01-01

    研究了硅烷偶联剂KH-792改性纳米SiO2:对环氧树脂E-44/低分子质量聚酰胺LMWPA651固化体系凝胶时间的影响.结果表明:加入质量分数5%的纳米SiO2可以大幅度降低凝胶时间,且与体系配比无关;当低分子质量聚酰胺与环氧树脂的质量比值>0.6时,KH-792改性SiO2:比未改性SiO2更有利于体系凝胶时间的降低.%The effects of silane coupling agent KH -792 modified nano SiO2 on the gel time of epoxy resin E -44/ low molecular weight polyamide LMWPA651 curing system were investigated. The results showed that the gel time of the system with 5% nano SiO2 was significantly reduced and had nothing to do with the the ratio of LMWPA651 to E -44 . The KH -792 modified nano SiO2 was more effective than the unmodified nano SiO2 on the gel time shorten when the weight ratio of LMWPA651 to E -44 was higher than 0. 6.

  19. 不同树脂粘结剂及硅烷偶联剂对玻璃纤维桩与牙本质粘结强度的影响%Effect of different resin cements and silane coupling agents on bond strength of glass fiber post to root dentin

    Institute of Scientific and Technical Information of China (English)

    许诺; 胡书海; 杨洋; 任翔; 左恩俊

    2011-01-01

    [ Objective] To evaluate the influence of different resin cements and silane coupling agents on bond strength of glass fiber posts to root dentin. [Methods] Twenty -four sound single rooted teeth that had similar dimensions were selected. The coronal aspects were removed. After endodontic treatment and canal preparation,24 MATCHPOST glass fiber posts were cemented to the root canals. According to the different silane coupling agent,24 teeth root were randomly divided into two equal main groups of 12 each: A group (two components) and B group (single component). Teeth root from the two main groups were randomly distributed into there equal subgroups according to different resin cement: RU group (RelyX Unicem self - adhesive system) ; PF group (Panavia - F self - etching system) and DL group (DUO - LINK total - etching system). Each root was cut perpendicular to the long axis to obtain 3 slices with 3.0- mm - thick as test specimens. Specimens of each test group (n = 12) were loaded in an universal testing machine for push - out test. The dates obtained were submitted to the two - way ANOVA and multiple comparison (α = 0.05 ). Failure modes of specimens were observed and recorded. [ Results] Bond strength values ( Mpa) of six test groups from the highest to the lowest were as follows; B - RU (14. 8 ±5.17),B-PF (9.77±4.77),A-RU (9.42±4.93) ,A-PF (8.69 ±3.40) ,B - DL (5.71 ±2.71) and A-DL (5.22 ± 1.69). Silane coupling agent (compared A and B group,P =0.014) and resin cement (compared RU、PF and DL group,P =0.000) significantly effected bond strength,whereas the interaction between these two factors was not significant (P = 0.079). Post - hoc test revealed that significant differences (P < 0.05) could be found between every two groups of three (RU,PF and DL). [Conclusion] Self-adhesive resin cement (RU) show the better bond strength than self-etching (DL) and total - etching (PF). One - component silane coupling agent should be recommended in clinical.%[目

  20. Users, Bystanders and Agents

    DEFF Research Database (Denmark)

    Krummheuer, Antonia Lina

    2015-01-01

    Human-agent interaction (HAI), especially in the field of embodied conversational agents (ECA), is mainly construed as dyadic communication between a human user and a virtual agent. This is despite the fact that many application scenarios for future ECAs involve the presence of others. This paper...... the construction of the agent’s identity, and (3) how HAI, as a mediated interaction, is framed by an asymmetric participation framework. The paper concludes by suggesting various participation roles, which may inform development of ECAs....

  1. Agent-Based Optimization

    CERN Document Server

    Jędrzejowicz, Piotr; Kacprzyk, Janusz

    2013-01-01

    This volume presents a collection of original research works by leading specialists focusing on novel and promising approaches in which the multi-agent system paradigm is used to support, enhance or replace traditional approaches to solving difficult optimization problems. The editors have invited several well-known specialists to present their solutions, tools, and models falling under the common denominator of the agent-based optimization. The book consists of eight chapters covering examples of application of the multi-agent paradigm and respective customized tools to solve  difficult optimization problems arising in different areas such as machine learning, scheduling, transportation and, more generally, distributed and cooperative problem solving.

  2. AGENT code - neutron transport benchmark examples

    International Nuclear Information System (INIS)

    The paper focuses on description of representative benchmark problems to demonstrate the versatility and accuracy of the AGENT (Arbitrary Geometry Neutron Transport) code. AGENT couples the method of characteristics and R-functions allowing true modeling of complex geometries. AGENT is optimized for robustness, accuracy, and computational efficiency for 2-D assembly configurations. The robustness of R-function based geometry generator is achieved through the hierarchical union of the simple primitives into more complex shapes. The accuracy is comparable to Monte Carlo codes and is obtained by following neutron propagation through true geometries. The computational efficiency is maintained through a set of acceleration techniques introduced in all important calculation levels. The selected assembly benchmark problems discussed in this paper are: the complex hexagonal modular high-temperature gas-cooled reactor, the Purdue University reactor and the well known C5G7 benchmark model. (author)

  3. Polypropylene nanocomposites: effect of coupling agent on structure and properties

    Czech Academy of Sciences Publication Activity Database

    Kotek, Jiří; Kelnar, Ivan; Studenovský, Martin

    Dresden : Max Planck Institute for the Physic of Complex Systems, 2005. [MPG-MOEL– Symposium: Science and Art in Europe, Polymers: Materials in Nature and in Advanced Technologies. 23.5.2005-25.5.2005, Dresden] R&D Projects: GA AV ČR(CZ) IBS4050351 Keywords : polypropylene * nanocomposites * melt-compounding Subject RIV: CD - Macromolecular Chemistry

  4. Novel Phenylethynyl Imide Silanes as Coupling Agents for Titanium Alloy

    Science.gov (United States)

    Park, C.; Lowther, S. E.; Smith, J. G., Jr.; Conell, J. W.; Hergenrother, P. M.; SaintClair, T. L.

    2004-01-01

    The durability of titanium (Ti) alloys bonded with high temperature adhesives such as polyimides has failed to attain the level of performance required for many applications. The problem to a large part is attributed to the instability of the surface treatment on the Ti substrate. Although Ti alloy adhesive specimens with surface treatments such as chromic acid anodization, Pasa-Jell, Turco, etc. have provided high initial mechanical properties, these properties have decreased as a function of aging at ambient temperature and faster, when aged at elevated temperatures or in a hot-wet environment. As part of the High Speed Civil Transport program where Ti honeycomb sandwich structure must perform for 60,000 hours at 177 C, work was directed to the development of environmentally safe, durable Ti alloy surface treatments.

  5. One-Dimensional RuO2/Mn2O3 Hollow Architectures as Efficient Bifunctional Catalysts for Lithium-Oxygen Batteries.

    Science.gov (United States)

    Yoon, Ki Ro; Lee, Gil Yong; Jung, Ji-Won; Kim, Nam-Hoon; Kim, Sang Ouk; Kim, Il-Doo

    2016-03-01

    Rational design and massive production of bifunctional catalysts with fast oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics are critical to the realization of highly efficient lithium-oxygen (Li-O2) batteries. Here, we first exploit two types of double-walled RuO2 and Mn2O3 composite fibers, i.e., (i) phase separated RuO2/Mn2O3 fiber-in-tube (RM-FIT) and (ii) multicomposite RuO2/Mn2O3 tube-in-tube (RM-TIT), by controlling ramping rate during electrospinning process. Both RM-FIT and RM-TIT exhibited excellent bifunctional electrocatalytic activities in alkaline media. The air electrodes using RM-FIT and RM-TIT showed enhanced overpotential characteristics and stable cyclability over 100 cycles in the Li-O2 cells, demonstrating high potential as efficient OER and ORR catalysts. PMID:26821307

  6. A bifunctional chromogenic and fluorogenic probe for F{sup −} and Al{sup 3+} based on azo-benzimidazole conjugate

    Energy Technology Data Exchange (ETDEWEB)

    Iniya, Murugan; Jeyanthi, Dharmaraj; Krishnaveni, Karuppiah; Chellappa, Duraisamy, E-mail: dcmku123@gmail.com

    2015-01-15

    A versatile bifunctional probe has been reported for selective individual detection of Al{sup 3+} and F{sup −} through “turn-on” chromogenic and fluorogenic dual modes. The photonic behaviors of probe upon addition of analyte have been determined using UV–vis absorption, fluorescence emission, quantum yield and fluorescence life-time measurement. Density functional theory calculations have been performed to establish the nature of interaction between probe and Al{sup 3+}/F{sup −}. - Highlights: • First report on azo based bifunctional chromogenic and fluorogenic chemosensor for Al{sup 3+} and F{sup −} with varied responses. • The probe displays simple method of synthesis, reversibility towards Al{sup 3+} and high stability. • TD–DFT calculations were performed to characterize the nature of fluorescent behavior of probe upon addition of Al{sup 3+} and F{sup −}.

  7. The amino acid sequence of a 20 kDa bifunctional subtilisin/alpha-amylase inhibitor from bran [correction of brain] of rice (Oryza sativa L.) seeds.

    Science.gov (United States)

    Ohtsubo, K; Richardson, M

    1992-08-31

    A 20 kDa bifunctional inhibitor of the microbial proteinase, subtilisin, and the alpha-amylase from the larvae of the red flour beetle (Tribolium castaneum) was purified from bran of rice seeds by saline extraction, precipitation with ammonium sulphate, ion-exchange chromatography on DEAE-Cellulose and Toyopearl CM-650, and preparative HPLC on Vydac C18. The complete primary structure was determined by automatic degradation of the intact, reduced and S-alkylated protein, and by manual DABITC/PITC micro-sequencing of peptides obtained from the protein following separate enzymic digestions with trypsin, pepsin, chymotrypsin, elastase and the protease from S. aureus V8. The protein sequence, which contained 176 residues, showed strong homology with similar bifunctional inhibitors previously isolated from wheat and barley which are related to the Kunitz family of proteinase inhibitors from legume seeds. PMID:1511747

  8. Decoupling Coupled Constraints Through Utility Design

    Energy Technology Data Exchange (ETDEWEB)

    Li, N; Marden, JR

    2014-08-01

    Several multiagent systems exemplify the need for establishing distributed control laws that ensure the resulting agents' collective behavior satisfies a given coupled constraint. This technical note focuses on the design of such control laws through a game-theoretic framework. In particular, this technical note provides two systematic methodologies for the design of local agent objective functions that guarantee all resulting Nash equilibria optimize the system level objective while also satisfying a given coupled constraint. Furthermore, the designed local agent objective functions fit into the framework of state based potential games. Consequently, one can appeal to existing results in game-theoretic learning to derive a distributed process that guarantees the agents will reach such an equilibrium.

  9. Agent Standards Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation of the work herein proposed is the development of standards for software autonomous agents. These standards are essential to achieve software...

  10. Tubular Coupling

    Science.gov (United States)

    Rosenbaum, Bernard J. (Inventor)

    2000-01-01

    A system for coupling a vascular overflow graft or cannula to a heart pump. A pump pipe outlet is provided with an external tapered surface which receives the end of a compressible connula. An annular compression ring with a tapered internal bore surface is arranged about the cannula with the tapered internal surface in a facing relationship to the external tapered surface. The angle of inclination of the tapered surfaces is converging such that the spacing between the tapered surfaces decreases from one end of the external tapered surface to the other end thereby providing a clamping action of the tapered surface on a cannula which increases as a function of the length of cannula segment between the tapered surfaces. The annular compression ring is disposed within a tubular locking nut which threadedly couples to the pump and provides a compression force for urging the annular ring onto the cannula between the tapered surfaces. The nut has a threaded connection to the pump body. The threaded coupling to the pump body provides a compression force for the annular ring. The annular ring has an annular enclosure space in which excess cannula material from the compression between the tapered surfaces to "bunch up" in the space and serve as an enlarged annular ring segment to assist holding the cannula in place. The clamped cannula provides a seamless joint connection to the pump pipe outlet where the clamping force is uniformly applied to the cannula because of self alignment of the tapered surfaces. The nut can be easily disconnected to replace the pump if necessary.

  11. Programming Service Oriented Agents

    OpenAIRE

    Hirsch, Benjamin; Konnerth, Thomas; Burkhardt, Michael; Albayrak, Sahin

    2010-01-01

    This paper introduces a programming language for service-oriented agents. JADL++ combines the ease of use of scripting-languages with a state-of-the-art service oriented approach which allows the seamless integration of web-services. Furthermore, the language includes OWL-based ontologies for semantic descriptions of data and services, thus allowing agents to make intelligent decisions about service calls.

  12. Adrenal imaging agents

    International Nuclear Information System (INIS)

    The goals of this proposal are the development of selenium-containing analogs of the aromatic amino acids as imaging agents for the pancreas and of the adrenal cortex enzyme inhibitors as imaging agents for adrenal pathology. The objects for this year include (a) the synthesis of methylseleno derivatives of phenylalanine and tryptophan, and (b) the preparation and evaluation of radiolabeled iodobenzoyl derivatives of the selenazole and thiazole analogs of metyrapone and SU-9055

  13. Catalytic Asymmetric Synthesis of Both Enantiomers of 4‑Substituted 1,4-Dihydropyridines with the Use of Bifunctional Thiourea-Ammonium Salts Bearing Different Counterions

    Directory of Open Access Journals (Sweden)

    Kohzo Yoshida

    2010-11-01

    Full Text Available Organoammonium salts composed of a Brønsted acid and an anilinothiourea promoted the Michael addition of β-keto esters and α,β-unsaturated aldehydes in the presence of primary amines to give functionalized 1,4-dihydropyridines enantioselectively. With the use of the different Brønsted acids such as DFA and HBF4 with the same bifunctional thiourea, both enantiomers of 4-substituted 1,4-dihydropyridine were synthesized from the same starting materials.

  14. In-situ X-Ray Absorption Spectroscopy (XAS) Investigation of a Bifunctional Manganese Oxide Catalyst with High Activity for Electrochemical Water Oxidation and Oxygen Reduction

    OpenAIRE

    Gorlin, Yelena; Lassalle-Kaiser, Benedikt; Benck, Jesse D.; Gul, Sheraz; Webb, Samuel M; Yachandra, Vittal K.; Yano, Junko; Jaramillo, Thomas F.

    2013-01-01

    In-situ x-ray absorption spectroscopy (XAS) is a powerful technique that can be applied to electrochemical systems, with the ability to elucidate the chemical nature of electrocatalysts under reaction conditions. In this study, we perform in-situ XAS measurements on a bifunctional manganese oxide (MnOx) catalyst with high electrochemical activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Using x-ray absorption near edge structure (XANES) and extended x-r...

  15. Identification of catalytic sites for oxygen reduction and oxygen evolution in N-doped graphene materials: Development of highly efficient metal-free bifunctional electrocatalyst

    OpenAIRE

    Yang, Hong Bin; Miao, Jianwei; Hung, Sung-Fu; Chen, Jiazang; Tao, Hua Bing; Wang, Xizu; Zhang, Liping; Chen, Rong; Gao, Jiajian; Chen, Hao Ming; Dai, Liming; Liu, Bin

    2016-01-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical to renewable energy conversion and storage technologies. Heteroatom-doped carbon nanomaterials have been reported to be efficient metal-free electrocatalysts for ORR in fuel cells for energy conversion, as well as ORR and OER in metal-air batteries for energy storage. We reported that metal-free three-dimensional (3D) graphene nanoribbon networks (N-GRW) doped with nitrogen exhibited superb bifunctional electroca...

  16. Discovery of Bifunctional Oncogenic Target Inhibitors against Allosteric Mitogen-Activated Protein Kinase (MEK1) and Phosphatidylinositol 3-Kinase (PI3K).

    Science.gov (United States)

    Van Dort, Marcian E; Hong, Hao; Wang, Hanxiao; Nino, Charles A; Lombardi, Rachel L; Blanks, Avery E; Galbán, Stefanie; Ross, Brian D

    2016-03-24

    The synthesis of a series of single entity, bifunctional MEK1/PI3K inhibitors achieved by covalent linking of structural analogs of the ATP-competitive PI3K inhibitor ZSTK474 and the ATP-noncompetitive MEK inhibitor PD0325901 is described. Inhibitors displayed potent in vitro inhibition of MEK1 (0.015 strategy toward combined MEK1/PI3K inhibition. PMID:26943489

  17. All-optical OR/NOR Bi-functional logic gate by using cross-gain modulation in semiconductor optical amplifiers

    International Nuclear Information System (INIS)

    An OR/NOR bi-functional all-optical logic gate has been experimentally demonstrated at 10 Gbit/s by using cross-gain modulation (XGM) in only 2 semiconductor optical amplifiers (SOAs). One SOA was used for NOR operation and the other SOA was used for inversion to obtain OR operation. Numerical simulation has also been performed, which coincided well with the experimental results.

  18. Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors.

    Science.gov (United States)

    Zhang, Ming-Liang; Yue, Deng-Feng; Wang, Zhen-Hua; Luo, Yuan; Xu, Xiao-Ying; Zhang, Xiao-Mei; Yuan, Wei-Cheng

    2016-01-01

    For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee). PMID:26977188

  19. Bifunctional RNAs Targeting the Intronic Splicing Silencer N1 Increase SMN Levels and Reduce Disease Severity in an Animal Model of Spinal Muscular Atrophy

    OpenAIRE

    Osman, Erkan Y; Yen, Pei-Fen; Lorson, Christian L.

    2011-01-01

    Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by loss of survival motor neuron-1 (SMN1). A nearly identical copy gene, SMN2, is present in all SMA patients. Although the SMN2 coding sequence has the potential to produce full-length SMN, nearly 90% of SMN2-derived transcripts are alternatively spliced and encode a truncated protein. SMN2, however, is an excellent therapeutic target. Previously, we developed antisense-based oligonucleotides (bifunctional RNAs) that specifi...

  20. Agent amplified communication

    Energy Technology Data Exchange (ETDEWEB)

    Kautz, H.; Selman, B.; Milewski, A. [AT& T Laboratories, Murray Hill, NJ (United States)

    1996-12-31

    We propose an agent-based framework for assisting and simplifying person-to-person communication for information gathering tasks. As an example, we focus on locating experts for any specified topic. In our approach, the informal person-to-person networks that exist within an organization are used to {open_quotes}referral chain{close_quotes} requests for expertise. User-agents help automate this process. The agents generate referrals by analyzing records of e-mail communication patterns. Simulation results show that the higher responsiveness of an agent-based system can be effectively traded for the higher accuracy of a completely manual approach. Furthermore, preliminary experience with a group of users on a prototype system has shown that useful automatic referrals can be found in practice. Our experience with actual users has also shown that privacy concerns are central to the successful deployment of personal agents: an advanced agent-based system will therefore need to reason about issues involving trust and authority.

  1. Self-assembly of cobalt-centered metal organic framework and multiwalled carbon nanotubes hybrids as a highly active and corrosion-resistant bifunctional oxygen catalyst

    Science.gov (United States)

    Fang, Yiyun; Li, Xinzhe; Li, Feng; Lin, Xiaoqing; Tian, Min; Long, Xuefeng; An, Xingcai; Fu, Yan; Jin, Jun; Ma, Jiantai

    2016-09-01

    Metal organic frameworks (MOF) derived carbonaceous materials have emerged as promising bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts for electrochemical energy conversion and storage. But previous attempts to overcome the poor electrical conductivity of MOFs hybrids involve a harsh high-template pyrolytic process to in situ form carbon, which suffer from extremely complex operation and inevitable carbon corrosion at high positive potentials when OER is operated. Herein, a self-assembly approach is presented to synthesize a non-precious metal-based, high active and strong durable Co-MOF@CNTs bifunctional catalyst for OER and ORR. CNTs not only improve the transportation of the electrons but also can sustain the harsh oxidative environment of OER without carbon corrosion. Meanwhile, the unique 3D hierarchical structure offers a large surface area and stable anchoring sites for active centers and CNTs, which enables the superior durability of hybrid. Moreover, a synergistic catalysis of Co(II), organic ligands and CNTs will enhance the bifunctional electrocatalytic performance. Impressively, the hybrid exhibits comparable OER and ORR catalytic activity to RuO2 and 20 wt% Pt/C catalysts and superior stability. This facile and versatile strategy to fabricating MOF-based hybrids may be extended to other electrode materials for fuel cell and water splitting applications.

  2. A bifunctional Delta12,Delta15-desaturase from Acanthamoeba castellanii directs the synthesis of highly unusual n-1 series unsaturated fatty acids.

    Science.gov (United States)

    Sayanova, Olga; Haslam, Richard; Guschina, Irina; Lloyd, David; Christie, William W; Harwood, John L; Napier, Johnathan A

    2006-12-01

    The free-living soil protozoon Acanthamoeba castellanii synthesizes a range of polyunsaturated fatty acids, the balance of which can be altered by environmental changes. We have isolated and functionally characterized in yeast a microsomal desaturase from A. castellanii, which catalyzes the sequential conversion of C(16) and C(18) Delta9-monounsaturated fatty acids to di- and tri-unsaturated forms. In the case of C(16) substrates, this bifunctional A. castellanii Delta12,Delta15-desaturase generated a highly unusual fatty acid, hexadecatrienoic acid (16:3Delta(9,12,15)(n-1)). The identification of a desaturase, which can catalyze the insertion of a double bond between the terminal two carbons of a fatty acid represents a new addition to desaturase functionality and plasticity. We have also co-expressed in yeast the A. castellanii bifunctional Delta12,Delta15-desaturase with a microsomal Delta6-desaturase, resulting in the synthesis of the highly unsaturated C(16) fatty acid hexadecatetraenoic acid (16:4Delta(6,9,12,15)(n-1)), previously only reported in marine microorganisms. Our work therefore demonstrates the feasibility of the heterologous synthesis of polyunsaturated fatty acids of the n-1 series. The presence of a bifunctional Delta12,Delta15-desaturase in A. castellanii is also considered with reference to the evolution of desaturases and the lineage of this protist. PMID:16950768

  3. Dispatching mobile Agents for DDM applicationss

    Institute of Scientific and Technical Information of China (English)

    LI Xi-ning; Guillaume Autran

    2008-01-01

    Techniques for mining information from distributed data sources accessible over the Internet are a growing area of research. The mobile Agent paradigm opens a new door for distributed data mining and knowledge discovery applications. In this paper we present the design of a mobile agent system which couples service discovery, using a logical language based application programming interface, and database access. Combining mobility with database access provides a means to create more efficient data mining applications. The processing of data is moved to network wide data locations instead of the traditional approach of bringing huge amount of data to the processing location. Our proposal aims at implementing system tools that will enable intelligent mobile Agents to roam the Internet searching for distributed data services. Agents access the data, discover patterns, extract useful information from facts recorded in the databases, then communicate local results back to the user. The user then generates a global data model through the aggregation of results provided by all Agents. This overcomes barriers posed by network congestion, poor security, and unreliability.

  4. Exfoliated Pd/HNb3O8 nanosheet as highly efficient bifunctional catalyst for one-pot cascade reaction

    Science.gov (United States)

    Lee, Nahaeng; Chung, Young-Min

    2016-05-01

    Ultrathin two-dimensional metal oxide nanosheets have drawn attention as potential solid acid catalysts owing to their strong acidity, attributed to the bridged OH groups formed on the nanosheets. In this study, a new class of bifunctional acid-metal catalyst was realized by the deposition of Pd on layered niobium oxide (KNb3O8 and HNb3O8) or its exfoliated nanosheet (Pd/HNb3O8-NS) and applied to one-pot cascade deacetalization and hydrogenation. It was found that the acid strength of the support exerted a large influence not only on the promotion of the first deacetalization step, but also on the acceleration of the subsequent hydrogenation step. Comparative experiments using a series of Pd/HZSM-5 catalysts with different acidities reconfirmed the crucial role of acid strength on hydrogenation. However, the superior catalytic activity of Pd/HNb3O8-NS for hydrogenation compared to that of Pd/HZSM-5 of similar acidity suggests a more efficient ensemble effect of the strong acid sites with the nearby metal sites on the nanosheet surface. Among the catalysts used, Pd/HNb3O8-NS showed the best catalytic performance for one-pot cascade reaction affording the desired product (benzyl alcohol) in approximately 92% yield, which was 7.1 and 1.2 times higher than that of layered Pd/KNb3O8 or Pd/HNb3O8, respectively. The excellent catalytic performance of Pd/HNb3O8-NS may result from the characteristic features of nanosheets: (i) the synergistic cooperation between the bifunctional active sites and (ii) the two-dimensional open surface offering easier access of the reactants to the active sites. Although the use of NaBH4 as hydrogen source was effective in improving the initial reaction performance, the basic nature of NaBH4 adversely resulted in weakening the acid strength of the catalyst, and consequently led to a reduction in catalytic activity.

  5. Imaging cancer using PET - the effect of the bifunctional chelator on the biodistribution of a 64Cu-labeled antibody

    International Nuclear Information System (INIS)

    Introduction: Use of copper radioisotopes in antibody radiolabeling is challenged by reported loss of the radionuclide from the bifunctional chelator used to label the protein. The objective of this study was to investigate the relationship between the thermodynamic stability of the 64Cu-complexes of five commonly used bifunctional chelators (BFCs) and the biodistribution of an antibody labeled with 64Cu using these chelators in tumor-bearing mice. Methods: The chelators [S-2-(aminobenzyl)1,4,7-triazacyclononane-1,4,7-triacetic acid (p-NH2-Bn-NOTA): 6-[p-(bromoacetamido)benzyl]-1, 4, 8, 11-tetraazacyclotetradecane-N, N', N'', N'''-tetraacetic acid (BAT-6): S-2-(4-aminobenzyl)-1,4,7,10-tetraazacyclododocane tetraacetic acid (p-NH2-Bn-DOTA): 1,4,7,10-tetraazacyclododocane-N, N', N', N''-tetraacetic acid (DOTA): and 1-N-(4-aminobenzyl)-3,6,10,13,16,19-hexaazabicyclo[6.6.6]eicosane-1, 8-diamine (SarAr)] were conjugated to the anti-GD2 antibody ch14.18, and the modified antibody was labeled with 64Cu and injected into mice bearing subcutaneous human melanoma tumors (M21) (n = 3-5 for each study). Biodistribution data were obtained from positron emission tomography images acquired at 1, 24 and 48 hours post-injection, and at 48 hours post-injection a full ex vivo biodistribution study was carried out. Results: The biodistribution, including tumor targeting, was similar for all the radioimmunoconjugates. At 48 h post-injection, the only statistically significant differences in radionuclide uptake (p 64Cu]ch14.18-p-NH2-Bn-NOTA was 4.74 ± 0.77 per cent of the injected dose per gram of tissue (%ID/g), and for [64Cu]ch14.18-SarAr was 8.06 ± 0.77 %ID/g. Differences in tumor targeting correlated with variations in tumor size rather than which BFC was used. Conclusions: The results of this study indicate that differences in the thermodynamic stability of these chelator-Cu(II) complexes were not associated with significant differences in uptake of the tracer by the tumor

  6. Spherical nitrogen-doped hollow mesoporous carbon as an efficient bifunctional electrocatalyst for Zn-air batteries

    Science.gov (United States)

    Hadidi, Lida; Davari, Elaheh; Iqbal, Muhammad; Purkait, Tapas K.; Ivey, Douglas G.; Veinot, Jonathan G. C.

    2015-12-01

    Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO2 template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling.Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO2 template that is removed upon hydrofluoric acid etching. The morphology and structural

  7. Y2O3: Eu3+, Tb3+ spherical particles based anti-reflection and wavelength conversion bi-functional films: Synthesis and application to solar cells

    International Nuclear Information System (INIS)

    Highlights: • Eu3+ and Tb3+ co-doped Y2O3 particles were successfully prepared. The as prepared particles can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. • Y2O3 is not only a good photoluminescence host material, but also it has high corrosion resistivity, thermal stability, and transparency from violet to infrared light. Cooperated with SiO2 sols, it could realize a better anti-reflection property. • As a proof-of-concept application, the as prepared bi-functional films could effectively improve the photoelectric conversion efficiency by 0.23% compared to pure SiO2 AR coating film and 0.55% compared to glass. - Abstract: In this study, Eu3+ and Tb3+ co-doped Y2O3 particles were prepared via the simple, cost-effective urea homogeneous precipitation method without additives. The chosen particles were added in the SiO2 sols to get anti-reflection (AR) and wavelength conversion bi-functional films. Careful investigations were carried out to find the optimum preparation conditions and proper morphology. SEM images showed that the particle sizes reduced as metal ion/urea ratio decreased. Additionally, the extracted particles turned from sphere to lamellar type when the deionized water, which was used as solvent, reduced to a certain extent. The mechanisms of the morphology formation and diversification were proposed as well. The as prepared materials can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. The spherical sample showed better luminescence performance than the one with lamellar morphology. In addition, the optical transmittance spectra indicated that the films adding spherical particles had better anti-reflective performance, and the best adding amount was 0.08 g. Finally, As a proof-of-concept application, the as prepared bi-functional films were used to test the standard

  8. Agent Oriented Programming进展%Advances in Agent Oriented Programming

    Institute of Scientific and Technical Information of China (English)

    王一川; 石纯一

    2002-01-01

    Agent-oriented programming (AOP) is a framework to develop agents, and it aims to link the gap betweentheory and practical in agent research. The core of an AOP framework is its language and semantics. In this paper,we propose the necessary properties which agents should have, and then give a summary and analysis about differentAOP languages based on these properties.

  9. Agents unleashed a public domain look at agent technology

    CERN Document Server

    Wayner, Peter

    1995-01-01

    Agents Unleashed: A Public Domain Look at Agent Technology covers details of building a secure agent realm. The book discusses the technology for creating seamlessly integrated networks that allow programs to move from machine to machine without leaving a trail of havoc; as well as the technical details of how an agent will move through the network, prove its identity, and execute its code without endangering the host. The text also describes the organization of the host's work processing an agent; error messages, bad agent expulsion, and errors in XLISP-agents; and the simulators of errors, f

  10. El agente encubierto

    OpenAIRE

    Anaya Marcos, María del Carmen

    2015-01-01

    [ES] El trabajo versa sobre la figura del agente encubierto. Debemos enmarcar tal medida de investigación dentro del ámbito de la criminalidad organizada. Actualmente, estamos asistiendo a una proliferación de la delincuencia organizada. La sociedad ha evolucionado, y con ella la delincuencia. Fruto de tal evolución fue necesario incluir en nuestra Ley de Enjuiciamiento Criminal medidas extraordinarias de investigación, y una de ellas es el agente encubierto. Se trata de una medida muy polémi...

  11. The PLS agent : agent behavior validation by partial least squares

    OpenAIRE

    Lorscheid, Iris; Meyer, Matthias; Pakur, Sandra; Ringle, Christian

    2014-01-01

    Agent-based modeling is widely applied in the social sciences. However, the validation of agent behavior is challenging and identified as one of the shortcomings in the field. Methods are required to establish empirical links and support the implementation of valid agent models. This paper contributes to this, by introducing the PLS agent concept. This approach shows a way to transfer results about causalities and decision criteria from empirical surveys into an agent-based decision model, th...

  12. Smart systems and simple agents: industry pricing by parallel rules

    OpenAIRE

    Raymond Board; Tinsley, P A

    1996-01-01

    A standard macroeconomic specification is that the aggregate economy is directed by a single, smart representative agent using optimal decision rules. This paper explores an alternative conjecture--that the dynamic behavior of markets is often better interpreted as the interactions of many heterogeneous, rule-of-thumb agents who are loosely coupled in smart systems--much like the contrast of a single serial processor with global information versus parallel processors with limited communicatio...

  13. Bifunctional Silica-Coated Superparamagnetic FePt Nanoparticles for Fluorescence/MR Dual Imaging

    Directory of Open Access Journals (Sweden)

    Syu-Ming Lai

    2012-01-01

    Full Text Available Recently, superparamagnetic chemically disordered face-centered cubic (fcc FePt nanoparticles have been demonstrated as superior negative contrast agents for magnetic resonance imaging (MRI. However, their low intracellular labeling efficiency has limited the potential usage and the nanotoxicity of the particles requires attention. We have developed fluorescein isothiocyanate-incorporated silica-coated FePt (FePt@SiO2-FITC nanoparticles that exhibited not only a significant T1 and T2 MR contrast abilities but also a fluorescent property without significant cytotoxicities. These results suggest that silica-coated superparamagnetic FePt nanoparticles are potential nanodevices for the combination of fluorescence and MRI contrast used for cancer diagnosis.

  14. Targeting lipopolyplexes using bifunctional peptides incorporating hydrophobic spacer amino acids: synthesis, transfection, and biophysical studies.

    Science.gov (United States)

    Pilkington-Miksa, Michael A; Writer, Michele J; Sarkar, Supti; Meng, Qing-Hai; Barker, Suzie E; Shamlou, Parviz Ayazi; Hailes, Helen C; Hart, Stephen L; Tabor, Alethea B

    2007-01-01

    We have developed efficient synthetic routes to two hydrophobic amino acids, suitably protected for solid-phase peptide synthesis, and have successfully synthesized peptides containing these or other hydrophobic amino acids as spacers between a Lys16 moiety and an integrin-targeting motif. These peptides have in turn been used to formulate a range of lipopolyplex vectors with Lipofectin and plasmid DNA. The transfection efficiencies of these vectors and their aggregation behavior in buffers and in serum have been studied. We have shown that vectors containing peptides incorporating long linkers that are entirely hydrophobic are less efficient transfection agents. However, linkers of equivalent length that are in part hydrophobic show improved transfection properties, which is probably due to the improved accessibility of the integrin-binding motif. PMID:17915956

  15. Trading Agents for Roaming Users

    OpenAIRE

    Boman, Magnus; Bylund, Markus; Espinoza, Fredrik; Danielson, Mats; Lyback, David

    2002-01-01

    Some roaming users need services to manipulate autonomous processes. Trading agents running on agent trade servers are used as a case in point. We present a solution that provides the agent owners with means to upkeeping their desktop environment, and maintaining their agent trade server processes, via a briefcase service.

  16. Software Agent Techniques in Design

    DEFF Research Database (Denmark)

    Hartvig, Susanne C

    1998-01-01

    This paper briefly presents studies of software agent techniques and outline aspects of these which can be applied in design agents in integrated civil engineering design environments.......This paper briefly presents studies of software agent techniques and outline aspects of these which can be applied in design agents in integrated civil engineering design environments....

  17. 13 CFR 107.1620 - Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent. 107.1620 Section 107.1620 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL BUSINESS INVESTMENT COMPANIES SBA Financial Assistance...

  18. Programming multi-agent systems

    NARCIS (Netherlands)

    Dastani, Mehdi

    2015-01-01

    With the significant advances in the area of autonomous agents and multi-agent systems in the last decade, promising technologies for the development and engineering of multi-agent systems have emerged. The result is a variety of agent-oriented programming languages, development frameworks, executio

  19. Plasmodium AdoMetDC/ODC bifunctional enzyme is essential for male sexual stage development and mosquito transmission.

    Science.gov (United States)

    Hart, Robert J; Ghaffar, Atif; Abdalal, Shaymaa; Perrin, Benjamin; Aly, Ahmed S I

    2016-01-01

    Polyamines are positively-charged organic molecules that are important for cellular growth and division. Polyamines and their synthesizing enzymes are particularly abundant in rapidly proliferating eukaryotic cells such as parasitic protozoa and cancer cells. Polyamine biosynthesis inhibitors, such as Elfornithine, are now being considered for cancer prevention and have been used effectively against Trypanosoma brucei Inhibitors of polyamine biosynthesis have caused growth arrest of Plasmodium falciparum blood stages in vitro, but in P. berghei only partial inhibition has been observed. While polyamine biosynthesis enzymes are characterized and conserved in Plasmodium spp., little is known on the biological roles of these enzymes inside malaria parasite hosts. The bifunctional polyamine biosynthesis enzyme S-adenosyl methionine decarboxylase/ornithine decarboxylase (AdoMetDC/ODC) was targeted for deletion in P. yoelii Deletion of AdoMetDC/ODC significantly reduced blood stage parasitemia but Anopheles transmission was completely blocked. We showed that male gametocytogenesis and male gamete exflagellation were abolished and consequently no ookinetes or oocyst sporozoites could be generated from adometdc/odc(-) parasites. Supplementation of putrescine and spermidine did not rescue the defective phenotypes of male gametocytes and gametes of the knockout parasites. These results highlight the crucial role of polyamine homeostasis in the development and functions of Plasmodium erythrocytic stages in the blood and in the mosquito vector and validate polyamine biosynthesis pathway enzymes as drug targeting candidates for malaria parasite transmission blocking. PMID:27387533

  20. The synthesis and properties of bifunctional and intelligent Fe3O4@titanium oxide core/shell nanoparticles.

    Science.gov (United States)

    Yin, Yichao; Liu, Chenjie; Wang, Baoxiang; Yu, Shoushan; Chen, Kezheng

    2013-05-21

    A simple, one-pot solvothermal method has been demonstrated for the preparation of bifunctional Fe3O4@titanium oxide core/shell nanoparticles. In a typical procedure, tetraalkoxyl titanium Ti(OC4H9)4 and FeCl3 as precursors were added into ethylene glycol and further solvothermal treatment was used to synthesize the core/shell particles. The core/shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), SQUID MPMS and rheometry. The morphological results showed titanium oxide nanorods with 100-200 nm length and 10-20 nm diameter coated on the surface of 200-300 nm Fe3O4 submicrospheres. Reaction time, the titanium source, the barium salt etc. have an influence on the morphology of core/shell particles. The core/shell particles can not only respond to an external magnetic field, but also to an electric field--a novel application of electrorheological fluid. PMID:23532087

  1. Hierarchical NiCo2 O4 Hollow Microcuboids as Bifunctional Electrocatalysts for Overall Water-Splitting.

    Science.gov (United States)

    Gao, Xuehui; Zhang, Hongxiu; Li, Quanguo; Yu, Xuegong; Hong, Zhanglian; Zhang, Xingwang; Liang, Chengdu; Lin, Zhan

    2016-05-17

    Bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte may improve the efficiency of overall water splitting. Nickel cobaltite (NiCo2 O4 ) has been considered a promising electrode material for the OER. However, NiCo2 O4 that can be used as an electrocatalyst in HER has not been studied yet. Herein, we report self-assembled hierarchical NiCo2 O4 hollow microcuboids for overall water splitting including both the HER and OER reactions. The NiCo2 O4 electrode shows excellent activity toward overall water splitting, with 10 mA cm(-2) water-splitting current reached by applying just 1.65 V and 20 mA cm(-2) by applying just 1.74 V across the two electrodes. The synthesis of NiCo2 O4 microflowers confirms the importance of structural features for high-performance overall water splitting. PMID:27061909

  2. Comprehensive Study of an Earth-Abundant Bifunctional 3D Electrode for Efficient Water Electrolysis in Alkaline Medium.

    Science.gov (United States)

    Sharifi, Tiva; Gracia-Espino, Eduardo; Jia, Xueen; Sandström, Robin; Wågberg, Thomas

    2015-12-30

    We report efficient electrolysis of both water-splitting half reactions in the same medium by a bifunctional 3D electrode comprising Co3O4 nanospheres nucleated on the surface of nitrogen-doped carbon nanotubes (NCNTs) that in turn are grown on conductive carbon paper (CP). The resulting electrode exhibits high stability and large electrochemical activity for both oxygen and hydrogen evolution reactions (OER and HER). We obtain a current density of 10 mA/cm(2) in 0.1 M KOH solution at overpotentials of only 0.47 and 0.38 V for OER and HER, respectively. Additionally, the experimental observations are understood and supported by analyzing the Co3O4:NCNT and NCNT:CP interfaces by ab initio calculations. Both the experimental and the theoretical studies indicate that firm and well-established interfaces along the electrode play a crucial role on the stability and electrochemical activity for both OER and HER. PMID:26629887

  3. Preparation and characterization of bifunctional oxidative and acidic catalysts Nb2O5/TS-1 for synthesis of diols

    International Nuclear Information System (INIS)

    Bifunctional oxidative and acidic catalyst was prepared by incorporation of titanium ion (Ti4+) and niobic acid in zeolite molecular-sieve. The catalysts being active both in oxidation reactions due to the presence of tetrahedral Ti4+, and acid-catalyzed reactions due to the presence of niobic acid. Nb/TS-1 was prepared by hydrothermal synthesis of TS-1, calcination in air and subsequent impregnation of niobium into TS-1. The sample was characterized by XRD, FTIR, UV-vis DR, TPR and pyridine adsorption techniques. The XRD analysis of Nb/TS-1 revealed that the MFI structure of the TS-1 support was found to be intact upon incorporation of niobium. The infrared spectra showed that the tetrahedral titanium in the TS-1 is still remained after impregnation with niobium while based on the UV-vis DR result, the niobium species are in the octahedral structure. On the basis TPR and infrared of hydroxyl groups results, it is concluded that niobium species interacted with the silanols on the surface of TS-1. Pyridine adsorption study shows both Bronsted and Lewis acid sites are present in Nb/TS-1. The catalytic results in the transformation of 1-octene to 1,2-octanediol through the formation of 1,2-epoxyoctane by using Nb/TS-1 indicate that the production of epoxide and diol was correlated with the presence of oxidative and Bronsted acidic sites in the catalyst

  4. Simultaneous H2 Generation and Biomass Upgrading in Water by an Efficient Noble-Metal-Free Bifunctional Electrocatalyst.

    Science.gov (United States)

    You, Bo; Jiang, Nan; Liu, Xuan; Sun, Yujie

    2016-08-16

    As an environmentally friendly approach to generate H2 , electrocatalytic water splitting has attracted worldwide interest. However, its broad employment has been inhibited by costly catalysts and low energy conversion efficiency, mainly due to the sluggish anodic half reaction, the O2 evolution reaction (OER), whose product O2 is not of significant value. Herein, we report an efficient strategy to replace OER with a thermodynamically more favorable reaction, the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), catalyzed by 3D Ni2 P nanoparticle arrays on nickel foam (Ni2 P NPA/NF). HMF is one of the primary dehydration intermediates of raw biomass and FDCA is of many industrial applications. As a bifunctional electrocatalyst, Ni2 P NPA/NF is not only active for HMF oxidation but also competent for H2 evolution. In fact, a two-electrode electrolyzer employing Ni2 P NPA/NF for simultaneous H2 and FDCA production required a voltage at least 200 mV smaller compared with pure water splitting to achieve the same current density, as well as exhibiting robust stability and nearly unity Faradaic efficiencies. PMID:27417546

  5. Asymmetric Michael Additions of 4-Hydroxycoumarin to β-Nitrostyrenes with Chiral, Bifunctional Hydrogen-Bonding Catalysts.

    Science.gov (United States)

    Wolf, Florian F; Klare, Helge; Goldfuss, Bernd

    2016-03-01

    Enantioselective Michael additions of 4-hydroxycoumarin to β-nitrostyrenes are catalyzed by different chiral, bifunctional hydrogen-bonding catalysts, based on thiourea- and squaramide motifs. The scope of the catalysis is tested by employing a series of substituted β-nitrostyrenes as well as different solvents. The 3,5-bis(trifluoromethyl)phenyl- and quinine-substituted squaramide catalyst is shown to be the most selective catalyst, resulting in 78% yield and 81% ee. Computational analyses of transition structures with different binding modes show that the most favored transition structure exhibits squaramide (NH)2 binding to an oxygen atom of the enolate nucleophile, while the nitroalkene coordinates via hydrogen bonding to the ammonium function of the quinuclidine unit of the catalyst. Hence, the canted directionality of the squaramide (NH)2 motif, favoring one-atom binding, might be decisive for the selectivity of the reaction. The absolute configuration of the major (-)-(R) enantiomer of the product is assigned computationally according to its optical rotation. PMID:26815792

  6. Catalytic Upgrading of 5-Hydroxymethylfurfural to Drop-in Biofuels by Solid Base and Bifunctional Metal-Acid Catalysts.

    Science.gov (United States)

    Bohre, Ashish; Saha, Basudeb; Abu-Omar, Mahdi M

    2015-12-01

    Design and synthesis of effective heterogeneous catalysts for the conversion of biomass intermediates into long chain hydrocarbon precursors and their subsequent deoxygenation to hydrocarbons is a viable strategy for upgrading lignocellulose into distillate range drop-in biofuels. Herein, we report a two-step process for upgrading 5-hydroxymethylfurfural (HMF) to C9 and C11 fuels with high yield and selectivity. The first step involves aldol condensation of HMF and acetone with a water tolerant solid base catalyst, zirconium carbonate (Zr(CO3 )x ), which gave 92 % C9 -aldol product with high selectivity at nearly 100 % HMF conversion. The as-synthesised Zr(CO3 )x was analysed by several analytical methods for elucidating its structural properties. Recyclability studies of Zr(CO3 )x revealed a negligible loss of its activity after five consecutive cycles over 120 h of operation. Isolated aldol product from the first step was hydrodeoxygenated with a bifunctional Pd/Zeolite-β catalyst in ethanol, which showed quantitative conversion of the aldol product to n-nonane and 1-ethoxynonane with 40 and 56 % selectivity, respectively. 1-Ethoxynonane, a low oxygenate diesel range fuel, which we report for the first time in this paper, is believed to form through etherification of the hydroxymethyl group of the aldol product with ethanol followed by opening of the furan ring and hydrodeoxygenation of the ether intermediate. PMID:26549016

  7. Conversion of β-carotene into astaxanthin: Two separate enzymes or a bifunctional hydroxylase-ketolase protein?

    Directory of Open Access Journals (Sweden)

    Gudiña Eduardo

    2008-02-01

    Full Text Available Abstract Astaxanthin is a xanthophyll of great interest in animal nutrition and human health. The market prospect in the nutraceutics industries for this health-protective molecule is very promising. Astaxanthin is synthesized by several bacteria, algae and plants from β-carotene by the sequential action of two enzymes: a β-carotene, 3,3'-hydroxylase that introduces an hydroxyl group at the 3 (and 3' positions of each of the two β-ionone rings of β-carotene, and a β-carotene ketolase that introduces keto groups at carbons 4 and 4' of the β-ionone rings. Astaxanthin is also produced by the yeast-like basidiomycete Xanthophyllomyces dendrorhous. A gene crtS involved in the conversion of β-carotene to astaxanthin has been cloned simultaneously by two research groups. Complementation studies of X. dendrorhous mutants and expression analysis in Mucor circinelloides reveals that the CrtS enzyme is a β-carotene hydroxylase of the P-450 monooxygenase family that converts β-carotene to the hydroxylated derivatives β-cryptoxanthin and zeaxanthin, but it does not form astaxanthin or the ketolated intermediates in this fungus. A bifunctional β-carotene hydroxylase-ketolase activity has been proposed for the CrtS protein. The evidence for and against this hypothesis is analyzed in detail in this review.

  8. Biochemical characterization of a bifunctional acetaldehyde-alcohol dehydrogenase purified from a facultative anaerobic bacterium Citrobacter sp. S-77.

    Science.gov (United States)

    Tsuji, Kohsei; Yoon, Ki-Seok; Ogo, Seiji

    2016-03-01

    Acetaldehyde-alcohol dehydrogenase (ADHE) is a bifunctional enzyme consisting of two domains of an N-terminal acetaldehyde dehydrogenase (ALDH) and a C-terminal alcohol dehydrogenase (ADH). The enzyme is known to be important in the cellular alcohol metabolism. However, the role of coenzyme A-acylating ADHE responsible for ethanol production from acetyl-CoA remains uncertain. Here, we present the purification and biochemical characterization of an ADHE from Citrobacter sp. S-77 (ADHES77). Interestingly, the ADHES77 was unable to be solubilized from membrane with detergents either 1% Triton X-100 or 1% Sulfobetaine 3-12. However, the enzyme was easily dissociated from membrane by high-salt buffers containing either 1.0 M NaCl or (NH4)2SO4 without detergents. The molecular weight of a native protein was estimated as approximately 400 kDa, consisting of four identical subunits of 96.3 kDa. Based on the specific activity and kinetic analysis, the ADHES77 tended to have catalytic reaction towards acetaldehyde elimination rather than acetaldehyde formation. Our experimental observation suggests that the ADHES77 may play a pivotal role in modulating intracellular acetaldehyde concentration. PMID:26216639

  9. Key residues at the riboflavin kinase catalytic site of the bifunctional riboflavin kinase/FMN adenylyltransferase from Corynebacterium ammoniagenes.

    Science.gov (United States)

    Serrano, Ana; Frago, Susana; Herguedas, Beatriz; Martínez-Júlvez, Marta; Velázquez-Campoy, Adrián; Medina, Milagros

    2013-01-01

    Many known prokaryotic organisms depend on a single bifunctional enzyme, encoded by the RibC of RibF gene and named FAD synthetase (FADS), to convert Riboflavin (RF), first into FMN and then into FAD. The reaction occurs through the sequential action of two activities present on a single polypeptide chain where the N-terminus is responsible for the ATP:FMN adenylyltransferase (FMNAT) activity and the C-terminus for the ATP: riboflavin kinase (RFK) activity. Sequence and structural analysis suggest that T208, N210 and E268 at the C-terminus RFK module of Corynebacterium ammoniagenes FADS (CaFADS) might be key during RF phosphorylation. The effect of site-directed mutagenesis on the RFK activity, as well as on substrates and products binding, indicates that T208 and N210 provide the RFK active-site geometry for binding and catalysis, while E268 might be involved in the catalytic step as catalytic base. These data additionally suggest concerted conformational changes at the RFK module of CaFADS during its activity. Mutations at the RFK site also modulate the binding parameters at the FMNAT active site of CaFADS, altering the catalytic efficiency in the transformation of FMN into FAD. This observation supports the hypothesis that the hexameric assembly previously revealed by the crystal structure of CaFADS might play a functional role during catalysis. PMID:22892871

  10. SECOND BUYING AGENT

    CERN Multimedia

    SPL - SERVICES ACHATS

    2000-01-01

    Last year the buying agent LOGITRADE started operations on the CERN site, processing purchasing requests for well-defined families of products up to a certain value. It was planned from the outset that a second buying agent would be brought in to handle the remaining product families. So, according to that plan, the company CHARLES KENDALL will be commencing operations at CERN on 8 May 2000 in Building 73, 1st floor, offices 31 and 35 (phone and fax numbers to be announced).Each buying agent will have its own specific list of product families and will handle purchasing requests up to 10'000 CHF.Whenever possible they will provide the requested supplies at a price (including the cost of their own services) which must be equivalent to or lower than the price mentioned on the purchasing request, changing the supplier if necessary. If a lower price cannot be obtained, agents will provide the necessary administrative support free of charge.To ensure that all orders are processed in the best possible conditions, us...

  11. Radioactive diagnostic agent

    International Nuclear Information System (INIS)

    A dispersion of denatured aggregates of serum albumin to which tin is attached is prepared and lyophilized. A mixture of polycarboxylic acid and a disaccharide or monosaccharide is included in the dispersion in sufficient amount to reduce degradation during lyophilization and aging. The dispersion is suitable for radioactive labelling and use as a diagnostic agent

  12. Developing Enculturated Agents

    DEFF Research Database (Denmark)

    Rehm, Matthias

    Embodied Conversational Agents (ECAs) are complex multimodal systems with rich verbal and nonverbal repertoires. There human-like appearance raises severe expectations regarding natural communicative behaviors on the side of the user. But what is regarded as “natural” is to a large degree dependent...

  13. Biomimetic Emotional Learning Agents

    OpenAIRE

    Kenyon, Samuel H.

    2005-01-01

    This extended abstract proposes a type of AI agent comprised of: an autonomous real-time control system, low-level emotional learning (including a simple knowledge base that links homeostatic/innate drives to sensory perception states), and a novel sliding-priority drive motivation mechanism. Learning occurs in both phylogenetic and ontogenetic training.

  14. Agents of Change

    DEFF Research Database (Denmark)

    Hansen, Jens Aage; Lehmann, Martin

    2004-01-01

    at large, it emphasises universities as key change agents and providers in new learning, including tools such as project based and problem oriented learning (PBL) as well as information and communication technology (ICT); as providers of competent and motivated graduates to fill key positions in society...

  15. The need for agents

    DEFF Research Database (Denmark)

    Abolfazlian, Ali Reza Kian

    1996-01-01

    I denne artikel arbejder vi med begrebet Intelligent Software Agents (ISAs), som autonomous, social, reactive, proactive og subservient computer systemer. Baseret på socialt psykologiske argumenter viser jeg endvidere, hvordan både den menneskelige natur og det teknologiske stadium, som mennesket...

  16. Build Autonomic Agents with ABLE

    Institute of Scientific and Technical Information of China (English)

    吴吉义

    2007-01-01

    The IBM Agent Building and Learning Environment(ABLE) provides a lightweight Java~(TM) agent frame- work,a comprehensive JavaBeansTM library of intelligent software components,a set of development and test tools, and an agent platform.After the introduction to ABLE,classes and interfaces in the ABLE agent framework were put forward.At last an autonomic agent that is an ABLE-based architecture for incrementally building autonomic systems was discussed.

  17. Comparative research for micro-push-out bond strengths of glass fiber posts treated by poly-dopamine or silane coupling agent%玻璃纤维桩表面经聚多巴胺或硅烷化处理后的微推出粘接强度对比研究

    Institute of Scientific and Technical Information of China (English)

    陈倩; 苏永亮; 蔡晴; 白云洋; 苏靖; 王新知

    2015-01-01

    Objective:To evaluate the micro-push-out bond strengths of prefabricated glass fiber posts with poly-dopamine functionalized to root dentin using resin cements, contrasted with silane treatment. Methods:In the study, 30 glass fiber posts were randomly divided into 3 groups ( 10 posts in each group) for different surface treatments. Group 1, treated with poly-dopa; Group 2, treated with silane coupling agent for 60s;Group 3, no surface treatment (Control group). The 30 extracted human, single-rooted teeth were endodontically treated and a 9 mm post space was prepared in each tooth with post drills provided by the manufacturer. Following post cementation, the specimens were stored in distilled water at 37 ℃ for 7 days. The micro-push-out bond strengths were tested using a universal testing machine (0. 5 mm/min), and the failure modes were examined with a stereomicroscope. The data of the three groups were statistically analyzed using the one-way ANOVA test(α= 0. 05). Results:The bond strengths were (7. 909 ± 1. 987) MPa for Group 1, (5. 906 ± 0. 620) MPa for Group 2, and 4. 678 ± 0. 910 MPa for Group 3 . The bond strength of poly-dopamine group was significantly higher than that of the silane group (P<0. 05). Conclusion: Contrasted with silane treatment, surface poly-dopamine functionaliza-tion was confirmed to be a more reliable method for improving the bond strength of resin luting agents to fiber posts.%目的:对比玻璃纤维桩表面经聚多巴胺或硅烷偶联剂处理后与树脂水门汀的微推出粘接强度,探讨玻璃纤维桩表面聚多巴胺化学改性处理对其与树脂水门汀粘接强度的影响. 方法:将30支玻璃纤维桩随机分成3组,每组10支,组1为聚多巴胺组,组2为硅烷化组,组3为对照组. 将各组纤维桩与树脂水门汀在根管内进行粘接,用精密切片机切出微推出实验试件,测定其微推出粘接强度并观察破坏模式. 结果:组1(聚多巴胺组)微推出粘接强度为(7. 909

  18. Actions and Agents

    OpenAIRE

    Alonso, E.

    2014-01-01

    In this chapter the notion of agency in AI is presented..It has been argued that in order to behave rationally in prevalent software applications artificial entities would have to be autonomous and adaptive. Besides, rather than working with single, isolated systems the new trend in AI would need to focus on inherently social entities in the form of multi-agent systems. The chapter begins by introducing the notion of action in traditional AI systems, deliberative and reactive. Next, the i...

  19. Towards Soft Computing Agents

    Czech Academy of Sciences Publication Activity Database

    Neruda, Roman; Krušina, Pavel; Petrová, Zuzana

    2000-01-01

    Roč. 10, č. 5 (2000), s. 859-868. ISSN 1210-0552. [SOFSEM 2000 Workshop on Soft Computing. Milovy, 27.11.2000-28.11.2000] R&D Projects: GA ČR GA201/00/1489; GA ČR GA201/99/P057 Institutional research plan: AV0Z1030915 Keywords : hybrid systems * intelligent agents Subject RIV: BA - General Mathematics

  20. Sunscreening Agents: A Review

    OpenAIRE

    Latha, M. S.; Martis, Jacintha; Shobha, V; Sham Shinde, Rutuja; Bangera, Sudhakar; Krishnankutty, Binny; Bellary, Shantala; Varughese, Sunoj; Rao, Prabhakar; B R Naveen Kumar

    2013-01-01

    The increasing incidence of skin cancers and photodamaging effects caused by ultraviolet radiation has increased the use of sunscreening agents, which have shown beneficial effects in reducing the symptoms and reoccurrence of these problems. Many sunscreen compounds are in use, but their safety and efficacy are still in question. Efficacy is measured through indices, such as sun protection factor, persistent pigment darkening protection factor, and COLIPA guidelines. The United States Food an...

  1. Perioperative allergy: uncommon agents.

    Science.gov (United States)

    Caimmi, S; Caimmi, D; Cardinale, F; Indinnimeo, L; Crisafulli, G; Peroni, D G; Marseglia, G L

    2011-01-01

    Anesthesia may often be considered as a high-risk procedure and anaphylaxis remains a major cause of concern for anesthetists who routinely administer many potentially allergenic agents. Neuromuscular blocking agents, latex and antibiotics are the substances involved in most of the reported reactions. Besides these three agents, a wide variety of substances may cause an anaphylactic reaction during anesthesia. Basically all the administered drugs or substances may be potential causes of anaphylaxis. Among them, those reported the most in literature include hypnotics, opioids, local anesthetics, colloids, dye, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), Iodinated Contrast Media (ICM), antiseptics, aprotinin, ethylene oxyde and formaldehyde, and protamine and heparins. No premedication can effectively prevent an allergic reaction and a systematic preoperative screening is not justified for all patients; nevertheless, an allergy specialist should evaluate those patients with a history of anesthesia-related allergy. Patients must be fully informed of investigation results, and advised to provide a detailed report prior to future anesthesia. PMID:22014927

  2. Advanced scale conditioning agents

    International Nuclear Information System (INIS)

    A technical description of Advanced Scale Conditioning Agents (ASCA) technology was published in the May-June 2003 edition of the Nuclear Plant Journal. That article described the development of programs of advanced scale conditioning agents and specific types to maintain the secondary side of steam generators within a pressurized water reactor free of deposited corrosion products and corrosion-inducing contaminants to ensure their long-term operation. This article describes the first two plant applications of advanced scale conditioning agents implemented at Southern Nuclear Operating Company's Vogtle Units 1 and 2 during their 2002 scheduled outages to minimize tube degradation and maintain full power operation using the most effective techniques while minimizing outage costs. The goal was to remove three to four fuel cycles of deposits from each steam generator so that after future chemical cleaning activities, ASCAs could be used to maintain the cleanliness of the steam generators without the need for additional chemical cleaning efforts. The goal was achieved as well as several other benefits that resulted in cost savings to the plant

  3. SAM : Semantic Agent Model for SWRL rule-based agents

    OpenAIRE

    Subercaze, Julien; Maret, Pierre

    2010-01-01

    International audience SemanticWeb technologies are part of multi-agent engineering, especially regarding knowledge base support. Recent advances in the field of logic for the semantic web enable a new range of applications. Among them, programming agents based on semantic rules is a promising field. In this paper we present a semantic agent model that allows SWRL programming of agents. Our approach, based on the extended finite state machine concept, results in a three layers architecture...

  4. Collaborative Problem in Multi-agent System

    Institute of Scientific and Technical Information of China (English)

    林琳; 钟诗胜; 王知行

    2004-01-01

    In the MAS, system goal task can be decomposed into many transactions, which will be achieved by special agents distributed in different physical space. Due to complex coupling relations among transactions,transactions may form Waiting-Circle resulting in deadlock. Concerning the problem, this paper proposes two theorems developed for Waiting-Circle detection in transaction set and ensures the implement of goal task decomposition result. Furthermore, Circle-First Search is put forward to search all of the Waiting-Circle, which provide the basic guideline for decomposing goal task again and eliminate Waiting-Circle.

  5. Removing organic contaminants with bifunctional iron modified rectorite as efficient adsorbent and visible light photo-Fenton catalyst

    International Nuclear Information System (INIS)

    Highlights: ► Rectorite was modified by ultrasonic-assisted ion-exchange and hydrolysis. ► The pillaring increased the layer-to-layer spacing of rectorite. ► The iron-modified rectorite was found to be an excellent adsorbent. ► The iron-modified rectorite showed good visible light photocatalytic ability. ► FeR was highly chemically stable with a wide operating range of pH. - Abstract: Iron-modified rectorite (FeR) was prepared as both adsorbent and catalyst. The iron modification increased layer-to-layer spacing and surface area of rectorite, leading to much increased adsorption of Rhodamine B (RhB) on rectorite. The maximum adsorption capacity of RhB on FeR reached 101 mg g−1 at pH 4.5, being 11 folds of that on the unmodified one. The iron modification also enabled rectorite to have efficient visible light photocatalytic ability. The apparent rate constant for the degradation of RhB (80 μM) at 298 K and pH 4.5 in the presence of H2O2 (6.0 mM) and FeR (0.4 g L−1) was evaluated to be 0.0413 min−1 under visible light and 0.122 min−1 under sunlight, respectively. The analysis with electron spin resonance spin-trapping technique supported that the iron modified rectorite effectively catalyzed the decomposition of H2O2 into hydroxyl radicals. On the basis of the characterization and analysis, the new bifunctional material was well clarified as both adsorbent and photocatalyst in the removing of organic pollutants.

  6. A Novel N-Acetylglutamate Synthase Architecture Revealed by the Crystal Structure of the Bifunctional Enzyme from Maricaulis maris

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Dashuang; Li, Yongdong; Cabrera-Luque, Juan; Jin, Zhongmin; Yu, Xiaolin; Zhao, Gengxiang; Haskins, Nantaporn; Allewell, Norma M.; Tuchman, Mendel (Maryland); (GWU); (Georgia)

    2012-05-24

    Novel bifunctional N-acetylglutamate synthase/kinases (NAGS/K) that catalyze the first two steps of arginine biosynthesis and are homologous to vertebrate N-acetylglutamate synthase (NAGS), an essential cofactor-producing enzyme in the urea cycle, were identified in Maricaulis maris and several other bacteria. Arginine is an allosteric inhibitor of NAGS but not NAGK activity. The crystal structure of M. maris NAGS/K (mmNAGS/K) at 2.7 {angstrom} resolution indicates that it is a tetramer, in contrast to the hexameric structure of Neisseria gonorrhoeae NAGS. The quaternary structure of crystalline NAGS/K from Xanthomonas campestris (xcNAGS/K) is similar, and cross-linking experiments indicate that both mmNAGS/K and xcNAGS are tetramers in solution. Each subunit has an amino acid kinase (AAK) domain, which is likely responsible for N-acetylglutamate kinase (NAGK) activity and has a putative arginine binding site, and an N-acetyltransferase (NAT) domain that contains the putative NAGS active site. These structures and sequence comparisons suggest that the linker residue 291 may determine whether arginine acts as an allosteric inhibitor or activator in homologous enzymes in microorganisms and vertebrates. In addition, the angle of rotation between AAK and NAT domains varies among crystal forms and subunits within the tetramer. A rotation of 26{sup o} is sufficient to close the predicted AcCoA binding site, thus reducing enzymatic activity. Since mmNAGS/K has the highest degree of sequence homology to vertebrate NAGS of NAGS and NAGK enzymes whose structures have been determined, the mmNAGS/K structure was used to develop a structural model of human NAGS that is fully consistent with the functional effects of the 14 missense mutations that were identified in NAGS-deficient patients.

  7. CoSe₂ and NiSe₂ Nanocrystals as Superior Bifunctional Catalysts for Electrochemical and Photoelectrochemical Water Splitting.

    Science.gov (United States)

    Kwak, In Hye; Im, Hyung Soon; Jang, Dong Myung; Kim, Young Woon; Park, Kidong; Lim, Young Rok; Cha, Eun Hee; Park, Jeunghee

    2016-03-01

    Catalysts for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) are central to key renewable energy technologies, including fuel cells and water splitting. Despite tremendous effort, the development of low-cost electrode catalysts with high activity remains a great challenge. In this study, we report the synthesis of CoSe2 and NiSe2 nanocrystals (NCs) as excellent bifunctional catalysts for simultaneous generation of H2 and O2 in water-splitting reactions. NiSe2 NCs exhibit superior electrocatalytic efficiency in OER, with a Tafel slope (b) of 38 mV dec(-1) (in 1 M KOH), and HER, with b = 44 mV dec(-1) (in 0.5 M H2SO4). In comparison, CoSe2 NCs are less efficient for OER (b = 50 mV dec(-1)), but more efficient for HER (b = 40 mV dec(-1)). It was found that CoSe2 NCs contained more metallic metal ions than NiSe2, which could be responsible for their improved performance in HER. Robust evidence for surface oxidation suggests that the surface oxide layers are the actual active sites for OER, and that CoSe2 (or NiSe2) under the surface act as good conductive layers. The higher catalytic activity of NiSe2 is attributed to their oxide layers being more active than those of CoSe2. Furthermore, we fabricated a Si-based photoanode by depositing NiSe2 NCs onto an n-type Si nanowire array, which showed efficient photoelectrochemical water oxidation with a low onset potential (0.7 V versus reversible hydrogen electrode) and high durability. The remarkable catalytic activity, low cost, and scalability of NiSe2 make it a promising candidate for practical water-splitting solar cells. PMID:26848805

  8. The role of the methyltransferase domain of bifunctional restriction enzyme RM.BpuSI in cleavage activity.

    Directory of Open Access Journals (Sweden)

    Arthur Sarrade-Loucheur

    Full Text Available Restriction enzyme (REase RM.BpuSI can be described as a Type IIS/C/G REase for its cleavage site outside of the recognition sequence (Type IIS, bifunctional polypeptide possessing both methyltransferase (MTase and endonuclease activities (Type IIC and endonuclease activity stimulated by S-adenosyl-L-methionine (SAM (Type IIG. The stimulatory effect of SAM on cleavage activity presents a major paradox: a co-factor of the MTase activity that renders the substrate unsusceptible to cleavage enhances the cleavage activity. Here we show that the RM.BpuSI MTase activity modifies both cleavage substrate and product only when they are unmethylated. The MTase activity is, however, much lower than that of M1.BpuSI and is thought not to be the major MTase for host DNA protection. SAM and sinefungin (SIN increase the Vmax of the RM.BpuSI cleavage activity with a proportional change in Km, suggesting the presence of an energetically more favorable pathway is taken. We further showed that RM.BpuSI undergoes substantial conformational changes in the presence of Ca(2+, SIN, cleavage substrate and/or product. Distinct conformers are inferred as the pre-cleavage/cleavage state (in the presence of Ca(2+, substrate or both and MTase state (in the presence of SIN and substrate, SIN and product or product alone. Interestingly, RM.BpuSI adopts a unique conformation when only SIN is present. This SIN-bound state is inferred as a branch point for cleavage and MTase activity and an intermediate to an energetically favorable pathway for cleavage, probably through increasing the binding affinity of the substrate to the enzyme under cleavage conditions. Mutation of a SAM-binding residue resulted in altered conformational changes in the presence of substrate or Ca(2+ and eliminated cleavage activity. The present study underscores the role of the MTase domain as facilitator of efficient cleavage activity for RM.BpuSI.

  9. A novel N-acetylglutamate synthase architecture revealed by the crystal structure of the bifunctional enzyme from Maricaulis maris.

    Directory of Open Access Journals (Sweden)

    Dashuang Shi

    Full Text Available Novel bifunctional N-acetylglutamate synthase/kinases (NAGS/K that catalyze the first two steps of arginine biosynthesis and are homologous to vertebrate N-acetylglutamate synthase (NAGS, an essential cofactor-producing enzyme in the urea cycle, were identified in Maricaulis maris and several other bacteria. Arginine is an allosteric inhibitor of NAGS but not NAGK activity. The crystal structure of M. maris NAGS/K (mmNAGS/K at 2.7 Å resolution indicates that it is a tetramer, in contrast to the hexameric structure of Neisseria gonorrhoeae NAGS. The quaternary structure of crystalline NAGS/K from Xanthomonas campestris (xcNAGS/K is similar, and cross-linking experiments indicate that both mmNAGS/K and xcNAGS are tetramers in solution. Each subunit has an amino acid kinase (AAK domain, which is likely responsible for N-acetylglutamate kinase (NAGK activity and has a putative arginine binding site, and an N-acetyltransferase (NAT domain that contains the putative NAGS active site. These structures and sequence comparisons suggest that the linker residue 291 may determine whether arginine acts as an allosteric inhibitor or activator in homologous enzymes in microorganisms and vertebrates. In addition, the angle of rotation between AAK and NAT domains varies among crystal forms and subunits within the tetramer. A rotation of 26° is sufficient to close the predicted AcCoA binding site, thus reducing enzymatic activity. Since mmNAGS/K has the highest degree of sequence homology to vertebrate NAGS of NAGS and NAGK enzymes whose structures have been determined, the mmNAGS/K structure was used to develop a structural model of human NAGS that is fully consistent with the functional effects of the 14 missense mutations that were identified in NAGS-deficient patients.

  10. A novel N-acetylglutamate synthase architecture revealed by the crystal structure of the bifunctional enzyme from Maricaulis maris.

    Science.gov (United States)

    Shi, Dashuang; Li, Yongdong; Cabrera-Luque, Juan; Jin, Zhongmin; Yu, Xiaolin; Zhao, Gengxiang; Haskins, Nantaporn; Allewell, Norma M; Tuchman, Mendel

    2011-01-01

    Novel bifunctional N-acetylglutamate synthase/kinases (NAGS/K) that catalyze the first two steps of arginine biosynthesis and are homologous to vertebrate N-acetylglutamate synthase (NAGS), an essential cofactor-producing enzyme in the urea cycle, were identified in Maricaulis maris and several other bacteria. Arginine is an allosteric inhibitor of NAGS but not NAGK activity. The crystal structure of M. maris NAGS/K (mmNAGS/K) at 2.7 Å resolution indicates that it is a tetramer, in contrast to the hexameric structure of Neisseria gonorrhoeae NAGS. The quaternary structure of crystalline NAGS/K from Xanthomonas campestris (xcNAGS/K) is similar, and cross-linking experiments indicate that both mmNAGS/K and xcNAGS are tetramers in solution. Each subunit has an amino acid kinase (AAK) domain, which is likely responsible for N-acetylglutamate kinase (NAGK) activity and has a putative arginine binding site, and an N-acetyltransferase (NAT) domain that contains the putative NAGS active site. These structures and sequence comparisons suggest that the linker residue 291 may determine whether arginine acts as an allosteric inhibitor or activator in homologous enzymes in microorganisms and vertebrates. In addition, the angle of rotation between AAK and NAT domains varies among crystal forms and subunits within the tetramer. A rotation of 26° is sufficient to close the predicted AcCoA binding site, thus reducing enzymatic activity. Since mmNAGS/K has the highest degree of sequence homology to vertebrate NAGS of NAGS and NAGK enzymes whose structures have been determined, the mmNAGS/K structure was used to develop a structural model of human NAGS that is fully consistent with the functional effects of the 14 missense mutations that were identified in NAGS-deficient patients. PMID:22174908

  11. Synthesis and characterization of bifunctional transition-metal/silica-alumina catalysts for the chloromethane conversion to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, J.F. [Universidade Federal de Rio de Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Engenharia Quimica; Rojas, L.O.A.; Nascimento, J.C. [Universidade Federal de Rio de Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Engenharia Quimica; Centro de Tecnologias do Gas (CTGAS), Natal, RN (Brazil)], E-mail: leopoldo@ctgas.com.br; Ruiz, J.A.C. [Centro de Tecnologias do Gas (CTGAS), Natal, RN (Brazil); Benachour, M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Programa de Pos-Graduacao em Engenharia Quimica

    2008-10-15

    In this work bifunctional (metal-acid) catalysts of Fe, Ni, Fe{sub 2}O{sub 3} and NiO over amorphous silica alumina support were characterized (acidity) and evaluated for the conversion of chloromethane in a fixed bed reactor. Temperature program tests TPD (Temperature Programmed Desorption) and TPR (Temperature Programmed Reduction) were performed to characterize the chemisorption sites for the impregnated and unimpregnated support. New adsorption sites were created on the metal supported catalysts. The conversion yield of chloromethane was evaluated for the five materials. The highest conversion conversion (85%) was observed for the unmodified support (SiAl) after 6 of reaction at 860 K and a WHSV (Weight Hourly Space Velocity) of 4,5 h{sup -1}. The best selectivity toward desirable hydrocarbons (C{sup 3}, C{sup 4}) was found for the Fe-SiAl catalyst. C{sup 3} was also found in the products stream when Ni/SiAl and NiO/SiAl catalysts were tested. Ni catalysts were the most favorable to methane production. The catalytic tests showed coke formation in all materials. For the SiAl support the desorption energy of chloromethane, determined by TPD runs, was 101,9 KJ/mol. The metals presented lower desorption energies (75,2 KJ/mol for Ni and 133,4 KJ/mol for Fe) than the oxides (190,1 KJ/mol for Fe{sub 2}O{sub 3} and 322,4 KJ/mol for NiO). (author)

  12. Characterization of bifunctional L-glutathione synthetases from Actinobacillus pleuropneumoniae and Actinobacillus succinogenes for efficient glutathione biosynthesis.

    Science.gov (United States)

    Yang, Jianhua; Li, Wei; Wang, Dezheng; Wu, Hui; Li, Zhimin; Ye, Qin

    2016-07-01

    Glutathione (GSH), an important bioactive substance, is widely applied in pharmaceutical and food industries. In this work, two bifunctional L-glutathione synthetases (GshF) from Actinobacillus pleuropneumoniae (GshFAp) and Actinobacillus succinogenes (GshFAs) were successfully expressed in Escherichia coli BL-21(DE3). Similar to the GshF from Streptococcus thermophilus (GshFSt), GshFAp and GshFAs can be applied for high titer GSH production because they are less sensitive to end-product inhibition (Ki values 33 and 43 mM, respectively). The active catalytic forms of GshFAs and GshFAp are dimers, consistent with those of GshFPm (GshF from Pasteurella multocida) and GshFSa (GshF from Streptococcus agalactiae), but are different from GshFSt (GshF from S. thermophilus) which is an active monomer. The analysis of the protein sequences and three dimensional structures of GshFs suggested that the binding sites of GshFs for substrates, L-cysteine, L-glutamate, γ-glutamylcysteine, adenosine-triphosphate, and glycine are highly conserved with only very few differences. With sufficient supply of the precursors, the recombinant strains BL-21(DE3)/pET28a-gshFas and BL-21(DE3)/pET28a-gshFap were able to produce 36.6 and 34.1 mM GSH, with the molar yield of 0.92 and 0.85 mol/mol, respectively, based on the added L-cysteine. The results showed that GshFAp and GshFAs are potentially good candidates for industrial GSH production. PMID:26996628

  13. Production of propylene from 1-butene on highly active "bi-functional single active site" catalyst: Tungsten carbene-hydride supported on alumina

    KAUST Repository

    Mazoyer, Etienne

    2011-12-02

    1-Butene is transformed in a continuous flow reactor over tungsten hydrides precursor W-H/Al2O3, 1, giving a promising yield into propylene at 150 °C and different pressures. Tungsten carbene-hydride single active site operates as a "bi-functional catalyst" through 1-butene isomerization on W-hydride and 1-butene/2-butenes cross-metathesis on W-carbene. This active moiety is generated in situ at the initiation steps by insertion of 1-butene on tungsten hydrides precursor W-H/Al2O3, 1 followed by α-H and β-H abstraction. © 2011 American Chemical Society.

  14. Concerted bifunctionality of the dCTP deaminase-dUTPase from Methanocaldococcus jannaschii: A structural and pre-steady state kinetic analysis

    DEFF Research Database (Denmark)

    Siggaard, Julie; Johansson, Eva; Vognsen, Tina Reinholdt; Helt, Signe Smedegaard; Harris, Pernille; Larsen, Sine; Willemoës, Martin

    2009-01-01

    Two mutant dCTP deaminase-dUTPases from Methanocaldococcus jannaschii were crystallised and the crystal structures were solved: E145A in complex with the substrate analogue alpha,beta-imido-dUTP and E145Q in complex with diphosphate. Both mutant enzymes were defect in the deaminase reaction and had...... nucleotidyl diphosphorylase reaction was observed in the E145A:alpha,beta-imido-dUTP complex and positioned similarly as in the monofunctional trimeric dUTPase. A comparison of the active sites of the bifunctional enzyme and the monofunctional family members, dCTP deaminase and dUTPase, suggests similar...

  15. Electrocatalytic performances of g-C3N4-LaNiO3 composite as bi-functional catalysts for lithium-oxygen batteries

    OpenAIRE

    Yixin Wu; Taohuan Wang; Yidie Zhang; Sen Xin; Xiaojun He; Dawei Zhang; Jianglan Shui

    2016-01-01

    A low cost and non-precious metal composite material g-C3N4-LaNiO3 (CNL) was synthesized as a bifunctional electrocatalyst for the air electrode of lithium-oxygen (Li-O2) batteries. The composition strategy changed the electron structure of LaNiO3 and g-C3N4, ensures high Ni3+/Ni2+ ratio and more absorbed hydroxyl on the surface of CNL that can promote the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The composite catalyst presents higher activities than the individual...

  16. Organosilylated complex [Eu(TTA)₃(Bpy-Si)]: a bifunctional moiety for the engeneering of luminescent silica-based nanoparticles for bioimaging

    OpenAIRE

    Duarte, Adriana P.; Mauline, Léïla; Gressier, Marie; Dexpert-Ghys, Jeannette; Roques, Christine; Caiut, José Maurício A.; Deffune, Elenice; Maia, Danielle C. G.; Carlos, Iracilda Z; Ferreira, Antonio A. P.; Ribeiro, Sidney J.L.; Menu, Marie-Joëlle

    2013-01-01

    A new highly luminescent europium complex with the formula [Eu(TTA)₃(Bpy-Si)], where TTA stands for the thenoyltrifluoroacetone, (C₄H3S)COCH₂COCF₃, chelating ligand and Bpy-Si, Bpy-CH₂NH(CH₂)₃(OEt)₃, is an organosilyldipyridine ligand displaying a triethoxysilyl group as a grafting function has been synthesized and fully characterized. This bifunctional complex has been grafted onto the surface of dense silica nanoparticles (NPs) and on mesoporous silica microparticles as well. The covalent b...

  17. An Economic Model of Coupled Exponential Maps

    CERN Document Server

    López-Ruiz, R; Cosenza, M G; Sánchez, J R

    2007-01-01

    In this work, an ensemble of economic interacting agents is considered. The agents are arranged in a linear array where only local couplings are allowed. The deterministic dynamics of each agent is given by a map. This map is expressed by two factors. The first one is a linear term that models the expansion of the agent's economy and that is controlled by the {\\it growth capacity parameter}. The second one is an inhibition exponential term that is regulated by the {\\it local environmental pressure}. Depending on the parameter setting, the system can display Pareto or Boltzmann-Gibbs behavior in the asymptotic dynamical regime. The regions of parameter space where the system exhibits one of these two statistical behaviors are delimited. Other properties of the system, such as the mean wealth, the standard deviation and the Gini coefficient, are also calculated.

  18. Peripheral Neuropathy and Agent Orange

    Science.gov (United States)

    ... Enter ZIP code here Peripheral Neuropathy and Agent Orange VA presumes Veterans' early-onset peripheral neuropathy is related to their exposure to Agent Orange or other herbicides during service when the disease ...

  19. Agents Play Mix-game

    CERN Document Server

    Gou, C

    2005-01-01

    In mix-game which is an extension of minority game, there are two groups of agents; group1 plays the majority game, but the group2 plays the minority game. This paper studies the change of the average winnings of agents and volatilities vs. the change of mixture of agents in mix-game model. It finds that the correlations between the average winnings of agents and the mean of local volatilities are different with different combinations of agent memory length when the proportion of agents in group 1 increases. This study result suggests that memory length of agents in group1 be smaller than that of agent in group2 when mix-game model is used to simulate the financial markets.

  20. The Power Trading Agent Competition

    OpenAIRE

    Ketter, W.; Collins, J.; REDDY, P; Flath, C.

    2011-01-01

    This is the specification for the Power Trading Agent Competition for 2011 (Power TAC 2011). Agents are simulations of electrical power brokers, who must compete with each other for both power production and consumption, and manage their portfolios.